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An examination of marcasite and pyrite oxidative/dissolution rates in seawater

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Title:
An examination of marcasite and pyrite oxidative/dissolution rates in seawater
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xx, 198 leaves : ill. ; 29 cm
Language:
English
Creator:
Baldo, Gillian Leslie Robert
Publisher:
University of South Florida
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Tampa, Florida
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Subjects / Keywords:
Seawater -- Composition   ( lcsh )
Sulphide minerals -- Solubility   ( lcsh )
Hydrothermal vents   ( lcsh )
Dissertations, Academic -- Marine Science -- Doctoral -- USF   ( fts )

Notes

General Note:
Thesis (Ph. D.)--University of South Florida, 1992. Includes bibliographical references (leaves 68-74).

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University of South Florida
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University of South Florida
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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 028937593
oclc - 26535460
usfldc doi - F51-00179
usfldc handle - f51.179
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SFS0040068:00001


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AN EXAMINATION OF MARCASITE AND PYRITE OXIDATIVE/DISSOLUTION RATES IN SEAWATER by Gillian Leslie Robert Baldo A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Marine Science m the University of South Florida May 1992 Major Professor : Robert H. Byrne Ph D.

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Graduate Council University of South Florida Tampa, Florida CERTIFICATE OF APPROVAL Ph.D. Dissertation This IS to certify that the Ph.D. Dissertation of Gillian Leslie Robert Baldo with a major in the Department of Marine Science has been approved by the Examining Committee on April 10, 1992 as satisfactory for the dissertation requirement for the Ph.D. degree. Examining Committee : ----y--.---.,----,------Major Robert H. Byrne, Ph.D. M < -() Member: Peter Betzer, < Ph.D r-. Member: Edward Ph.D. X .... Wit-0.-KI
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ACKNOWLEDGE:MENTS The author wishes to express her smcere gratitude to Dr. Robert H. Byrne for his encouragement, guidance and helpful suggestions throughout this study and in the preparation of this manuscript. The author also wishes to express her appreciation to Dr. Peter Betzer, Dr William Sackett, Dr John Compton and Dr. Edward Van Vleet for their helpful suggestions throughout the course of this study. The author also gratefully acknowledges the SEM photomicrograph work by Tony Greco and the X-ray powder diffraction work by Terry Woods 11

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DEDICATION To my family for all their help and encouragement 111

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TABLE OF CONTENTS LIST OFT ABLES ........................ ....... ......... .......................... .... ......................... ....... vi LIST OF FIGURES ....................................... ............... ...................... ....... ............. ....... xii LIST OF SYMBOLS .. .................. .... ..... .... .... .................... ........................................... xiii ABSTRACT .... ............... ......... ....... ............................ ......... ............ ............................... xviii IN1RODUCDON .. .......... ............................ ................ .... . .............. ........... .................. SPECTROPHOTOMETRIC DETERMINATION OF SEAWATER PH ..... .......... 6 Introduction ... ........... ........... .... .............. ............ ......... ... ................................ 6 Experimental ................. .............. ... ...................... ............... ........................ ... !! Re s ults and Discu ss ion ... . ..... . . .................... ........................ ... ................ I 3 Summary of spectrophotometric determination of seawater pH ..................... ...................... ........ ...................... ... ............... . ..... 2 0 OXIDATION RATE EXPERIMENTS ........... .......... ..... ... ...... ......... ........................... 21 Introduction .... ................................ ......... .... ............ ............. .... ... .... .... ... ... 2 I Experimental ....................... ........... .... .......... ...... ...................... .............. .... 2 I Results and Discussion .......................... .... ........... .......... ... ..... .......... . ... .. .. 3 6 Summary of oxidation rate experiments ......... ..... ............................ .4 5 SPECTROPHOTOMETRIC DETERMINATION OF HYDROGEN ION EVOLUTION DURING PYRITE AND MARCASITE OXIDATION ................. .4 6 Introduction .... ............ ... ... ........ .... ........... .... ..... . . .... ...... ........ .... ...... ...... .... 4 6 Experimental ........ .... ...... .. ......... ......... ..... . .......... .. ....... .... . ................... ........ 5 I Total alkalinity calculation .............................................. .............. ...... .... 5 4 Results and Discu ssi on ....... ..... ............ .... . ....... .......... ..... .... ............... . . .. 5 8 Summary of hydrogen ion evolution rate experiments ..... ......... 6 4 SUMMARY .......... .... ...... ........ ............... ............................... .. .............................. ........ 66 LIST OF REFERENCES ........................................................................ .... .................... 6 8 APPENDICES .............................. ........................................ ... .......... ........ ... ............... ? 5 I Preparation of mineral samples ... ............ ... . .... ..... .... ....... ............ 7 6 2 Iron analysis after the method of Collins et al., (1959) Linearity and reproducibility evaluation .... ........................... ..... ? 9 3 Initial oxidation rate studies ...... .............. ..... ...................................... 8 2 4 Treatment to solubilize iron oxides ...... . ........... .................... .......... 8 8 5 Results of oxidation rate exp eri ments ... . ........ ... ........ .... ........... ... 9 2 6 Initial hydrogen ion evolution experiments ........ .. .. .... .. .... .......... .! 41 7 Results of hydro gen ion evolution experiments ........................ .14 9 8 Preliminary work with other sulfides .............. .... . ... ...... .... ......... .1 9 8 IV

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9 Calculation of dissolution times of particles of marcasite and pyrite ....... ....... ..... ... .... .......... .. ..... ..................... .......... 1 9 6 v

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LIST OF TABLES Table 1 Dissociation Constants of Phenol Red m Natural Seawater as a Function of Temperature 1 4 Table 2 Calculated and Values for Phenol Red at 0 and 25C 1 6 Table 3 Marcasite Oxidation Rates Table 4 Pyrite Oxidation Rates Table 5 Influence of Solution Variables on Marcasite and Pyrite Oxidation Rates 38 39 40 Table 6 Comparison of Pyrite and Marcasite Oxidation Rates 4 0 Table 7 Marcasite and Pyrite H+/Fe Ratios 59 Table 8 H+/Fe Ratios : Calculated with first data point omitted 6 1 Table 9 Comparison of iron concentrations in acid washed and pyrite/seawater suspensiOns 7 7 Table 10 Comparison of oxidation rates of pyrite samples treated and untreated for removal of fines 7 8 Table 11 Linearity of Calibration Measurements 80 Table 12 Reproducibility of Absorbance Maesurements 8 1 Table 13 Recovery of iron standard from seawater 89 Table 14 Comparison of iron concentration in treated seawater/iron standard solutions incubated for 0 and 48 hours 91 Table 15 Marcasite oxidation tn 0.7 M NaCl (10-4-86) 95 Table 16 Marcasite oxidation tn 0 7 M NaCl (10-5-86) 96 VI

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Table 17 Marcasite oxidation in 0 7 M NaCl (10 8-86) Table 18 Marcasite oxidation in 0 7 M NaCl (10-10-86) Table 19 Marcasite oxidation m seawater (1 0-31 86) Table 20 Marcasite oxidation m seawater (11-3-86) Table 21 Table 22 Table 23 Table 24 Table 25 Table 26 Table 27 Table 28 Table 29 Table 30 Table 31 Marcasite oxidation m seawater (11-4-86) Marcasite oxidation m seawater (11-13-86) Marcasite oxidation in 7% 02 (12 9 86) Marcasite oxidation m 7% 02 (12-13-86) Marcasite oxidation m 7 % 02 (12-17-86) Marcasite oxidation at low temperature (12-22-86) Marcasite oxidation at low temperature (1-3-87) Marcasite oxidation at low temperature (1-31-87) Marcasite oxidation at high pressure (3-7 -87) Marcasite oxidation at high pressure (3-14 87) Marcasite oxidation at high pressure (3-21-87) 96 97 97 98 98 99 99 100 101 102 103 104 105 106 108 Table 32 Marcasite oxidation at high pressure (3-26-87) 1 0 9 Table 33 Pyrite oxidation m 0.7 M NaCl (10-13-86) 111 Table 34 Pyrite oxidation m 0.7 M NaCl (10-14-86) Ill Table 35 Pyrite oxidation m 0.7 M NaCl (10 16-86) 112 Table 36 Pyrite oxidation m 0.7 M NaCl (10-17-86) 112 Table 37 Pyrite oxidation m seawater (10-28-86) 11 3 Table 38 Pyrite oxidation m seawater (10-29-86) Table 39 Pyrite oxidation m seawater (11-8 86) Table 40 Pyrite oxidation m seawater (11-9-86) Vll 113 114 1 14

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Table 41 Pyrite oxidation m 7% 02 (11-16-86) Table 42 Pyrite oxidation m 7% 02 (11-19-86) Table 43 Pyrite oxidation in 7% 02 (12-5-86) 1 15 116 11 7 Table 44 Pyrite oxidation at low temperature (1-14-87) I 1 8 Table 45 Pyrite oxidation at low temperature (1-19-87) I I 9 Table 46 Pyrite oxidation at low temperature (1-25-87) 120 Table 47 Pyrite oxidation at high pressure (2-19-87) I 21 Table 48 Pyrite oxidation at high pressure (2-23-87) 1 2 2 Table 49 Pyrite oxidation at high pressure (2-28-87) 1 2 4 Table 50 Pyrite oxidation at high pressure (3-1 0-87) I 2 5 Table 51 Summary of marcasite oxidation experiments m 0.7 M NaCl Study 1 13 0 Table 52 Summary of marcasite oxidation experiments m seawater Study 2 131 Table 53 Summary of marcasite oxidation experiments m 7% 02 Study 3 13 2 Table 54 Summary of marcasite oxidation experiments at low temperature Study 4 I 3 3 Table 55 Summary of marcasite oxidation experiments under high pressure Study 5 I 3 4 Table 56 Summary of pyrite oxidation experiments in 0.7 M NaCl Study 1 1 3 5 Table 57 Summary of pyrite oxidation experiments m seawater Study 2 136 Table 58 Summary of pyrite oxidation experiments m 7% 02 3 Table 59 Summary of pyrite oxidation experiments at low temperature Study 4 Vlll Study 137 138

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Table 60 Summary of pyrite oxidation experiments under high pressure Study 5 1 3 9 Table 61 Summary of average mineral blanks for iron oxidation experiments 140 Table 62 Marcasite hydrogen ton evolution m 0.7 M NaCl (1 0-4-86) 153 Table 63 Marcasite hydrogen ion evolution m 0.7 M NaCl (10-5-86) 154 Table 64 Marcasite hydrogen IOn evolution m 0 7 M NaCl (10-8-86) 155 Table 65 Marcasite hydrogen ion evolution m 0.7 M NaCl (10-1086) 156 Table 66 Marcasite hydrogen ion evolution m seawater (1 0-31-86) 157 Table 67 Marcasite hydrogen IOn evolution m seawater (11-3-86) 158 Table 68 Marcasite hydrogen IOn evolution m seawater ( 11-4-86 ) 159 Table 69 Marcasite hydrogen ion evolution in seawater (11-13-86) 160 Table 70 Marcasite hydrogen IOn evolution in 7% 02 (12-9-86) 1 61 Table 71 Marcasite hydrogen IOn evolution m 7% 02 (12-13-86) 162 Table 72 Marcasite hydrogen IOn evolution m 7 % 02 (12-17-86) 163 Table 73 Marcasite hydrogen ion evolution at low temperature (12-22-86) 164 Table 74 Marcasite hydro gen ton evolution at low temperature (1-3-87) 165 Table 75 Marcasite hydrogen wn evolution at low temperature (1-31-87) 167 IX

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Table 76 Pyrite hydrogen ton evolution m 0.7 M NaCl (1 0-13-86) 168 Table 77 Pyrite hydrogen ion evolution m 0.7 M NaCl (10-14-86) 169 Table 78 Pyrite hydrogen IOn evolution m 0.7 M NaCl (10-16-86) 170 Table 79 Pyrite hydrogen ion evolution m 0.7 M NaCl (10-17-86) 1 7 1 Table 80 Pyrite hydrogen IOn evolution m seawater (1 0-28-86) 1 7 2 Table 81 Pyrite hydrogen IOn evolution m seawater (1 0-29-86) 1 7 3 Table 82 Pyrite hydrogen ion evolution m seawater (11-8-86) 1 7 4 Table 83 Pyrite hydrogen ion evolution in seawater 1 7 5 Table 84 Pyrite hydrogen IOn evolution m 7% 02 (11-16-86) 1 7 6 Table 85 Pyrite hydrogen ion evolution m 7 % 02 (11-19-86) 1 7 7 Table 86 Pyrite hydrogen IOn evolution in 7 % 02 (12-5-86) 1 7 8 Table 87 Pyrite hydrogen IOn evolution at low temperature (1-14-87) 179 Table 88 Pyrite hydrogen IOn evolution at low temperature (1-19-87) 181 Table 89 Pyrite hydrogen ion evolution at low temperature (1-25-87) 183 Table 90 Parameters used to calculate total alkalinity 185 Table 91 Marcasite hydrogen ion evolution in 0 7 M NaCl Summary of results Study 1 1 8 8 Table 92 Marcasite hydrogen IOn evolution m seawater Summary of results Study 2 1 8 9 Table 93 Marcasite hydrogen IOn evolution m 7 % 02 Summary of results Study 3 1 8 9 X

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Table 94 Marcasite hydrogen ion evolution at low temperature Summary of results Study 4 1 9 0 Table 95 Pyrite hydrogen ion evolution in 0.7 M NaCl Summary of results Study 1 1 9 1 Table 96 Pyrite hydrogen ion evolution in seawater Summary of results Study 2 1 9 1 Table 97 Pyrite hydrogen ion evolution m 7% 02 -Summary of results Study 3 1 9 2 Table 98 Pyrite hydrogen ion evolution at low temperature Summary of results Study 4 1 9 3 Table 99 Sphalerite oxidation 1 9 6 XI

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LIST OF FIGURES Figure 1 Predicted and Experimental Values of pK1 1 5 Figure 2 Pyrite treated with ultrasound and acid washed 2 3 Figure 3 Pyrite acid washed 2 4 Figure 4 Pyrite incubated 6 days and acid washed 2 5 Figure 5 Initial oxidation experiment 2 8 4 Figure 6 Initial oxidation experiment 3 8 5 Figure 7 Initial oxidation experiment 4 8 7 Figure 8 Initial hydrogen IOn evolution rate 1 4 2 Figure 9 Initial hydrogen ion evolution rate 14 4 Figure 10 Initial hydrogen ion evolution rate Figure 11 Initial hydrogen ion evolution rate Figure 12 Initial hydrogen ion evolution rate Figure 13 Initial hydrogen IOn evolution rate Figure 14 Marcasite blank results for hydrogen IOn evolution experiments Figure 15 Pyrite blank results for hydrogen IOn evolution experiments 145 146 147 148 150 150 Figure 16 Change in total alkalinity with time-Marcasite Oxidation in seawater (11-3-86) 152 X11

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LIST OF SYMBOLS pH : -log [H+] C : degrees Celsius m V h -1 : millivolts per hour t : temperature oc nm : nanometers mmol/L : micromoles per liter M : moles per liter mM : micromoles per liter T : absolute temperature (Kelvin) mm : micrometers atm: atmospheres cal mol-1K -1 : calories per mole per degree Kelvin S : salinity N : gram equivalent weight per liter cycles/min : cycles per minute cm3 :cubic centimeters lb/in2 : pounds per square inch ca. : approximately ml : milliliter g : grams m, molal : moles per kilogram Xlll

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mmoles Fetotal/m 2F e S 2/hr micromoles total iron per square meter mineral per hour m 2/g : square meters per gram kJ : kiloj oules Cuvet : cell used for studies I through 4, labeled R I to R9 and TI to T9 for identification purposes Tube filmware container used as an incubation vessel for study 5 (high pressure), identified by a number in each experiment A593nm : studies I 4: blank and baseline drift corrected absorbance. mineral cone. concentration of mineral m moles per kg (H20). corr. (df) : correction factor for addition of HCl to solution. corr. (cf) : correction factor for removal of 5 mls of solution. corr. (hf) : correction factor for loss of solution due to evaporation. time (hrs) : time elapsed since addition of solution to mineral corrected for blank processing time. Feah : : Iron concentration corrected for loss due to evaporation and for addition of acid (assumes all of iron is in solution), expressed as moles total iron per moles mineral per hour Febh : (hf)(cf)([Fe]/mc) : Iron concentration corrected for loss due to heat, for addition of acid and removal of 5 mls of solution (assumes iron is not in solution but is adsorbed onto available surfaces), expressed as moles total iron per moles mineral per hour Feah(bc) : blank corrected, the average uon concentration of the mineral blanks has been subtracted from the test result. Febh(bc) : blank corrected, the average iron concentration of the mineral blanks has been subtracted from the test result. XIV

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Feah/hr(bc) : blank corrected uon concentration divided by elapsed time. Febh/hr(bc) : blank corrected iron concentration divided by elapsed time. problems : experimental problems resulting m deletion of data point is noted on this line wt : weight mar : marcasite pyr : pyrite blk, BLK, min blk : mineral blank, non-incubated SW blk : seawater blank, treated in same manner as test samples A593nm : study 5; (baseline drift corrected) absorbance at 593 nm A593nm sbc : study 5; absorbance at 593 nm corrected by subtraction of average A593 of seawater blanks (processed on the same day) Fe : study 5 total iron concentration moles per kilogram Fe(bc) : study 5 total iron concentration corrected for mineral blank Fe/hr(bc) : rate, study 5 blank corrected total iron concentration divided by time cuvet/exp : cuvet and experiment identified Feah/hr* : rate expressed in terms of moles total iron per square meter of mineral per hour Febh/hr* : rate expressed in terms of moles total uon per square meter of mineral per hour pH initial : pH on free hydrogen ton scale; studies 1 to 4, incubation medium pH determined from first absorbance reading at 558 nm; XV

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study 5, pH determined before experiment not corrected to experiment pressure and temperature Experiment means : mean of each experiment is determined Mean of exp. means : mean of experiment means is determined Mean of all cuvets : each cuvet from each experiment is weighted equally Standard deviation : sample standard deviation has been calculated from the formula: s = {L(x-x)2f(N -1) )1/2 P. standard deviation : population standard deviation has been calculated from the formula: s = (L(x-x)2fN} 1/2 Standard error : standard error of the mean has been calculated from the formula: sm = s/(N)l/2 (Formulas taken from Weinberg and Schumaker, 1974) ()TA/hr, dTA/dt : change in total alkalinity with time, not normalized for mineral surface area m/hr : moles per kilogram per hour /lTA *lilt : change in total alkalinity with time, normalized for mineral surface area All data : all of the data is used to calculate /lTA*/Ilt Omit 1st : the first absorbance reading is omitted from the calculation of /lTA *//lt reading : number of reading, 1 = first absorbance reading AS58 nm : absorbance at 558 nm corrected for baseline drift Time (hrs) : time of absorbance reading in hydrogen ion evolution studies Cell temp. : temperature of cell compartment of spectrophotometer, used in calculations xvi

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Temp K : temperature of incubating water bath sws : seawater scale, pHsw s = -log (mH) free H : free hydrogen ion scale ()p KB : ()pKB = pKB(frec H scale) pKB(sws) factor : factor= 1 + BHS04[S04-2 ] + BHF[F ], [H+] (free)(factor) = mH XVll

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AN EXAMINATION OF MARCASITE AND PYRITE OXIDATIVE/DISSOLUTION RATES IN SEAWATER by Gillian Leslie Robert Baldo An Abstract Of a dissertation submitted in partial fulfillment of the requirements for the of Doctor of Philosophy in the Department of Marine Science in the University of South Florida May 1992 Major Professor: Robert H Byrne Ph D. XVlll

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This work examined the oxidative/dissolution rates of pyrite and marcasite in seawater under various solution conditions. A spectrophotometric method for determining seawater pH was developed in the cour s e of this work The evolution of protons during pyrite and marcasite oxidation was monitored spectrophotometrically followed by spectrophotometric measurements of total evolved iron. Oxidation rate observations are described in the context of the evolution of hydrothermally derived particles at the Juan de Fuca Ridge. It was determined that the oxidative dissolution of marcasite and pyrite is strongly influenced by temperature a nd we a kly influenced by oxygen concentration. A temperature d ecrease from 25 C to 0.5 C resulted in an eleven fold decrease in the oxidation rate of marcasite and a nine-fold decrease for pyrit e. The sulfur oxidation products for pyrite are more oxidized than those of marcasite. The sulfur oxidation products for both pyrite and marcasite are less oxidi z ed in 0 7 M NaCl than in seawater. Observations indicate that the oxidation rates of marcasite and p y rite are very similar. Under conditions similar to those found in-situ around the Juan de Fuca Ridge, the oxidation rate of marcasite was 3.7 x I0-7 moles FeS2/hr/m2 and the oxidation rate of pyrite wa s 4.0 x I07 moles FeS2/hr/m2. XIX

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Abstract Approved _._+=_..__-..::.,. Major Professor : Robert H Byrne, Ph.D. Professor, Department of Marine Science -----t------'--------------------Date Approved XX

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INTRODUCTION This work examines the oxidative/dissolution rates of pyrite and marcasite in seawater under various solution conditions. A spectrophotometric method for determining seawater pH was developed in the course of my work. It was expected that the oxidative dissolution of pyrite and marcasite would produce pH changes which in conjunction with measurements of iron evolution would be diagnostic of oxidation mechanisms. The evolution of protons during pyrite and marcasite oxidation was monitored spectrophotometrically followed by spectrophotometric I measurements of total evolved uon. My oxidation rate observations are described 'in the context of the evolution of hydrothermally derived particles at the Juan de Fuca Ridge. The interest in sulfide mineral oxidation rates in seawater arises from their presence in hydrothermal vent plumes which are formed as a result of hydrothermal circulation of seawater beneath the mid-ocean spreading centers. Altered seawater exudes into oceanic bottom waters forming hydrothermal vents The mixing of this hot, metal-sulfide rich, reducing, and acidic fluid with cold oxygenated seawater results in the formation of precipitates,

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2 progenitors of metalliferous sediments associated with hydrothermal vents. "Black smoker" vents are found with high-exit temperatures ca. 350 C, along the Juan de Fuca Ridge The black smoker particulates consist primarily of metal sulfides: sphalerite (ZnS) pyrite (FeS2), chalcopyrite (CuFeS1.9), pyrrhotite (Fe1-o.sS), wurtzite (ZnS) and marcasite (FeS2); sulfates: anhydrite (CaS04), gypsum (CaS04), and barite (BaS04); and also some Fe and Ca silicates (Haymon and Kastner, 1981; Mottl, 1983; Feely et al., 1984, 1985, 1987; and Leinen, 1985). These precipitated particulates are believed to be metastable m oceanic waters. Their fate depends on particle size and reactivity. The particulates may dissolve/alter in the water column or near the water-sediment interface. Fast dissolving minerals in the water column would be indicative of recent hydrothermal vent activity. Comparative studies of mineral oxidative dissolution could allow dating of vent mineral deposits by examination of the mineral abundance ratios and should significantly increase understanding of the formation of metalliferous sediments and the ultimate fate of vent-particulates in the ocean. Knowledge of oxidation rates, effects of oceanic variables on these rates, and resulting alteration products are also useful in modeling the effects of hydrothermal venting on geochemical cycles and balances in the ocean. Marcasite and pyrite are both iron disulfides (FeS2 ) Pyrite is classified as isometric and diploidal, containing the structure cell

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Fe4 S g, four molecules per unit cell. Marcasite, which has a different crystal structure than pyrite, is classified as orthorhombic and dipyramidal, containing the structure cell Fe2S4, two molecules per unit cell (Dana and Dana, 1944) Marcasite (4.88 g/cm3 ) is slightly less dense than pyrite (5 .0 g/cm3). 3 Although there has been much work done on the oxidation of pyrite, most of the work concerns acid mine drainage and uranium geochemistry. Pyrite, as well as other economically important sulfides, have also been studied extensively with regard to high pressure leaching techniques under acidic conditions ( very high oxygen pressures and high temperatures) (Woodcock 1961; Warren, 1956). Much of the work done prior to 1982 can be found in a review by Nordstrom (1982) and also in an extensive review by Lowson (1982) Lowson examined physical and thermodynamic properties of pyrite and marcasite as well as chemical and electrochemical oxidative dissolution of pyrite and marcasite. More recently, in order to represent ground water in the formation of uramum deposits, McKibben and Barnes (1986) determined rate law s for pyrite oxidation at low temperature (20-40 o C) in acid chloride solutions with an ionic strength of 0 .01 M. Studies by Goldhaber, (1983) Moses et al (1987), and Nicholson et al. (1988 1990) included experiments performed under neutral or slightly alkaline conditions. Goldhaber ( 1983) examined pyrite oxidation rates in 0.1 M KCl at 30o C (pH 6 to 9) by monitoring the amount of base (NaOH) necessary to maintain the pyrite suspension at a steady pH and has also determined the sulfur intermediates in VIew of their possible

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4 role in uramum geochemistry. Under conditions of low ionic strength (0.02 m), initial pH 2 to 9 and temperatures between 22 to 25oC, Moses et al. (1987) examined the effects of sample preparation and oxidants (oxygen and Fe(III)) on the rates of pyrite oxidation by determination of the sulfur products. Nicholson et al. (1988, 1990) studied pyrite oxidation in carbonate buffered silica sand (3-25C) m order to understand how initially neutral environments become acidic in acid mine drainage Related to pyrite oxidation in seawater, Hood et al. (1989) looked at the effect of pH and solution composition on pyrite alteration products at 25oC in seawater analogs. However, no oxidation rate studies have been performed in seawater, nor in high ionic strength media at low temperatures and high hydrostatic pressures Without studies under in situ oceanic conditions, large uncertainties are associated with making predications about oxidation rates of these minerals in complex media such as seawater. Much less work has been done on marcasite Lowson (1982) has indicated that marcasite is more reactive than pyrite and will convert to pyrite over time. Several investigators have specifically considered the comparative rates of pyrite and marcasite but the conclusions vary. Wiersma and Rimstidt (1984) examined the oxidation of pyrite and marcasite from various sources in low wmc strength acidic ferric chloride solutions and took into account surface area differences between the minerals. Although they found hydrothermal pyrite to be ca 1.7 times more reactive than hydrothermal marcasite, they concluded that the small differences observed in rates are not geologically significant. Pugh et al. (1984)

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noted that the oxidation rates for marcasite are considerably faster than those of equivalent (surface area) amounts of pyrite under acidic conditions, but did not quantify the results Mathews and Robins (1974) and Goldhaber (1983) examined the amount of marcasite and pyrite left in oxidized material. Mathews and Robins (197 4) found no difference in the ratios of the minerals in coal, 5 before and after oxidation of "coal pyrite" under acidic conditions and concluded that pyrite and marcasite are oxid i zed at the same rate However, Goldhaber (1983) concluded that marcasite oxidizes much more rapidly than pyrite after observing in a Texas uranium deposit that marcasite was more significantly replaced by oxides than pyrite in grains which contained both minerals. Given this range of results under a variety of conditions, no certain predictions can be made about the relative rates of pyrite and marcasite in seawater under conditions similar to those found in-situ on the Juan de Fuca Ridge. No comparative studies on oxidation rates of pyrite and marcasite have been done in seawater.

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6 SPECTROPHOTOMETRIC DETERMINATION OF SEAWATER PH Introduction Seawater pH ts an essential component in quantitative descriptions of ocean chemistry. Oceanic processes and properties which are strongly pH-dependent include mineral solubility (Garrels and Christ, 1965), dissolution kinetics (Morse and Berner, 1979), chemical speciation and adsorption (Stumm and Morgan, 1981; Baes and Mesmer, 1979), bioavailability (Morel and Morel-Laurens, 1983), and redox kinetics and equilibria (Stumm and Morgan, 1981; Kester et al., 1975). Buffering of seawater pH is, on a short geological time scale, dominated by the oceanic C02 system. As a consequence of the direct relationship between pH and C02 partial pressure, examination of seawater pH using hydrogen electrodes is impractical, and such measurements are predominantly conducted with pH sensitive glass electrodes. Potentiometric cells containing glass electrodes have, in general, proven satisfactory in measurements of solution pH. However, the behavior of potentiometric cells in seawater pH measurements often falls short of what is deemed acceptable. Even with the most careful treatment, the potential of cells containing

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7 glass electrodes often drifts slowly with time (< 0.6 mVh-1) after such cells are placed in a new solution (Culberson, 1981). Drift of cell potentials makes rapid measurement of pH quite difficult and is an especially severe problem in investigations dependent on precise observation of small pH differences Measurements involving cells with liquid junctions are subject to further uncertainties due to the dependence of liquid junction potentials upon medium concentration and composition. Ideally, the change in liquid junction potential (residual liquid junction potential) between test solution and standardizing buffer should be small or at least highly reproducible. In practice, systematic errors between pH and pK measurements suggest (a) that the reproducibility of the residual liquid junction potential is often poor and (b) that residual liquid junction potentials are dependent on the construction and/or history of the liquid junctions used in various investigations (Culberson, 1981 ). As an alternative to potentiometric measurements, spectrophotometric techniques offer a variety of advantageous characteristics in determinations of seawater pH. Equilibration rates are dependent on aqueous molecular processes and are generally quite fast. Measurements can thereby be conducted rapidly, minimizing the contact time between seawater and surfaces susceptible to ion exchange. Spectrophotometric pH measurements in seawater are quite stable over periods of time much longer that those necessary for equilibration. This attribute in conjunction with the sensitivity of spectrophotometric methods, allows precise examination of small differences in pH.

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8 Seawater is an ideal medium for the employment of pHsensitive spectrophotometric dyes. The physical chemical characteristics of indicator dyes are expected to vary considerably with medium composition, concentration, and temperature (Bates, 1973). In seawater, however, medium composition is virtually invariant (Sverdrup et al. 1942; Millero, 197 4 ), concentration varies within a relatively small range (34 salinity 36) for 98% of the ocean's volume) (Montgomery, 1958), and, in much of the ocean, both salinity and temperature are substantially constant (0 t 6C and 34 salinity 35 for 79% of the ocean's volume) (Pickard and Emery, 1982). The uniform composition of ocean water (constancy of major component molar ratios) and very low concentrations of reactive trace elements (Brewer, 1975; Bruland, 1983) allow characterizations of an indicator's physical/chemical behavior to be expressed in terms of only three variables : temperature, pressure, and salinity. In this work, the behavior of phenol red in seawater Is quantitatively examined at 1 atm total pressure and temperatures between 5C and 30C. Phenol red was chosen for this investigation because its working range makes it especially suitable for use at the low temperature typical of most of the ocean. Characterizations of phenol red allow examination of the dissolution kinetics of marine aragonitic particulates (Byrne et al., 1984; Betzer et al., 1984 ); the respiration rates of small individual zooplankton (Morris and Byrne,

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1982) and the hydrogen ion evolution rates of sulfide minerals m seawater. Through the reactions ( 1 ) CaC03(s) + H+ = Ca2+ + HC039 seawater pH provides a sensitive indicator of mineral dissolution Use of pH-sensitive indicator dyes allow such processes to be conveniently examined in closed systems, which facilitates control of conditions. Also, as an added advantage for mineral dissolution experiments, closed systems are less susceptible to contamination. Conversion of the yellow, Dy, form of phenol red to the red, DR form is accompanied by the appearance of a strong absorbance band centered at 558 nm. The absorbance changes which accompany the interconversiOJ? of yellow and red forms can be quantitatively described by usmg the equation (Byrne and Kester, 1978) where "A.A is absorbance at wavelength A., L is path length, Dr is total dye concentration (Dr =[DR] + [Dy ]), "J...EY is the absorbance per molar

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centimeter of Dy at wavelength A., A.ER is the absorbance per molar centimeter of DR at wavelength A., K 1 is the dissociation constant appropriate to reaction 3 and brackets denote the concentration of each chemical species. (5) K1 =[DR] [H+]/[Dy], 1 0 Equation 4 can be converted to a form m which pH rather than A.a is the dependent variable (6) pH= pK1 + log{(!..a-A.Ev)/(A.ER-A.a)} where pK1 = -logK1 pH = -log[H+], and [H+] is on the free hydrogen ion scale in moles per kilogram of H20. Equation 6 can be further simplified by observing that at a dye concentration DT where A.A = A.aDTL, 1..Amin= A.EYDTL, and A.Amax = A.ERDTL. Equation 7 is a more convenient formulation than equation 6 because direct measurement of the product A.ERDTL obviates the need for independent measurements of DT and A.ER. The product A.Amax = A.ERDTL is easily measured when at high pH, DT = [DR]. A.Amin is measured as the observed absorbance when at low pH, DT = [Dy ]. Accordingly in separate measurements of J..A, A.Amin. and A.Amax equation 7 can be employed to determine pH by holding DTL constant. A further convenience of this procedure is derived from the observation that m

PAGE 32

a constant diameter, variable pathlength cell (le Noble and Schott, 1976; Byrne, 1984; le Noble and Schott, 1984) the application of pressure induces changes in both DT and L while maintaining a constant product DTL Experimental 1 1 Examinations of pK 1 as a function of temperature were conducted with seawater collected in the Gulf of Mexico The salinities of stock seawater media were determined with a Model 8400 Autosal salinometer. Phenol red stock solutions were prepared in deionized water using Eastman Kodak ACS phenol red in the sodium form. Phenol red stock solutions were added to each seawater medium at Jess than 1 to 600 mixing ratios. Each medium was further diluted with deionized water so that the final salinities of the test media were 35.0 0.1 with phenol red concentrations near 2 Jlmol/L. Test media were housed in an open top, 1 0-cm path length spectrophotometric cell which fit snugly in the thermostated (.1 C) well of a Cary 17D spectrophotometer Ports in the lid of the spectrophotometric cell permitted the simultaneous introduction of an Orion 8102 combination pH electrode (3 M KCl filling solution) and a mechanically driven stirring rod. This arrangement permitted the simultaneous measurement of both pH and absorbance. Measurements of pH were obtained with a Corning Model 130 pH meter and, through the use of Tris (0.0400 m) seawater buffer (Ramette et al., 1977), are reported on the free hydrogen ion concentration scale The absorbances of phenol red in seawater were

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1 2 measured against salinity 35.0 seawater reference solutions to which no phenol red had been added. Oilmont microburets (2 ml total capacity) were used to add HCl (1 M) to the spectrophotometric titration vessel. The senes of titration points (sssA, [H+]) thereby obtained were fit by using equation 4 m a nonlinear least squares analysis (Bates, 1973; Marquardt, 1963; SAS Institute, 1982), providing the phenol red dissociation constant, Kt. Subsequent to completion of 21 experiments usmg the procedures outlined above, an alternative procedure for the determination of pK was developed. As a minor modification of the techniques described above, titration points were obtained at pH as high as 9.3 The high pH data were obtained through addition of B(OH)3/NaB(OH)4 titrant solutions which were composed as NaOH sodium borate decahydrate mixtures in deionized water. The borate/boric acid mixtures were adjusted to produce upper bound pHs on the order of 9.4. This procedure obviated generation of brucite (Mg(OH)4) in the high pH microenvironments which occur upon direct addition of NaOH. Since the boric acid/borate titrant solutions raised the ionic strength of the solutions by about 1%, deionized water was used to obtain a formal ionic strength equivalent to salinity 35 seawater. The data obtained by use of these procedures were fit using equation 7, as follows: For each data set, sssAmax was initially estimated by using the 558A value obtained at the data set's highest pH. Amin was calculated by using the relationship

PAGE 34

(8) sssAmin /sssAmax = sssEy/sssER = 1.2 x I0-3 By use of titration data (sssA vs. pH) and initial estimates of Amax and A min. pK1 was calculated for each data point within the bounds 7.0 pH 8.3. The pK1 data so obtained were averaged and the result was used in conjunction with equation 7 to obtain refined estimates of Amax and Amin This procedure was repeated until no further changes in pK 1 were observed. Results and Discussion I 3 The pK1 results obtained m these investigations usmg equation 4 and equation 7 are shown in Table I. It is expected that the variation of pK with the absolute temperature (T = t + 273.15) can be represented by equations of the form (Ramette et al., 1977) (9) pK = A{f + B + C log(T) Using equation 7 in a nonlinear least squares analysis, the entire data set was used to obtain the parameters A, B, and C. The results of this analysis are provided as: (10) pK1 = (4834.00/T) 84.831 + 30.7580 log(T)

PAGE 35

Table 1 Dissociation Constants of Phenol Red in Natural Seawater! as a Function of Temperature Temperature pKt pKt Number of 'C (Data set 1)2 3 (Data set 2)2 4 ex peri men ts 5.7 7.724 0 002 2 5 8 7.716 0.018 3 10.4 7.653 0.003 3 11.2 7.645 1 14.6 7.605 0.003 2 15.4 7.587 0.003 3 20.0 7.546 0 .002 3 20.2 7.543 1 25.1 7.495 0.006 6 25.2 7.484 0.002 2 30.1 7.451 0 006 3 30.3 7.437 0.006 2 1 35 salinity and 1 atm total pressure. 2 The range provided with each pK, indicates half of the range of individual observations at each temperature. 3 Data set 1 pK's were derived by use of equation 4. 4 Data set 2 pK's were derived by use of equation 7. 1 4

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1 5 Equation 10 provides a good, smoothed description of the Kt results expressed in moles per kilogram of water. The pK behavior predicted by using equation 10 is shown as the solid line in Figure 1. The maximum residual shown in the figure is 0.0066 and the average residual is 0.004. The parameter estimates shown in equation 10 can be used to provide estimates of the thermodynamic properties of phenol red m seawater. The standard changes of enthalpy LlH0 entropy LlS0 and 7.75 r 7.70 7.65 X predictec 7 .60 pK1 data set 2 X 7 .55 0 7 .50 data set 1 7.45 X 7 .40 3.60 3 .53 3.47 3.41 3.35 3.30 3.25 1 000/T (1/K) Figure 1 Predicted and Experimental Values of pK1

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1 6 heat capacity .LlCp0 for the dissociation process tn natural salinity 35 seawater are given (Ramette et al., 1977) as (11) .LlH0 = R(A ln10 -CT) (12) .LlS0 = R(B ln10 + C + C lnT) (13) .LlCp0 = -RC where R = 1.9872 cal moi-l K-1. Table 2 Calculated .LlH0 .LlS0 AND .LlCp0 Values for Phenol Red at 0 and 25C T,K 273.15 298.15 5423 130 3895 280 -15.9 0 8 -61 16 -21.2 1.4 -61 16 Table 2 shows the .LlH0 .LlS0 and .LlCp0 values obtained at 25C and 0C using equation 10. The uncertainties shown in Table 2 encompass the range of values obtained when equation 9 and 11-13 are applied to the first, second, and combined data sets. The uncertainties provided with the central estimates indicate that .LlH0 and .LlS0 are much better defined than .LlCp0

PAGE 38

In order to generalize equation 10 to an appropriate range of oceanic conditions, the characterization of phenol red in seawater was extended to include the influence of salinity on pK1. 1 7 Investigations of pK 1 vs. salinity were conducted at 25C and 13C over a salinity range between 35.9 and 31.7 With equation 7, sssA and pH were simultaneously measured as salinity was reduced with deionized water. By accounting for the effect of dilution on Amax and Amin. pK1 was conveniently determined as a function of salinity. The result obtained in three experiments at each temperature, L\pK/L\S = -0.004, indicated that a 1 part per thousand salinity decrease results in a 0.004 increase in pK 1 No significant difference in this result was observed as a function of temperature. Consequently, the analyses indicate that the behavior of phenol red in natural seawater can be reasonably described by using the equation (14) pK1 = (4834 00/T) 84.831 + 30.7580logT + 0.004(35 S) Although use of this equation at temperatures lower than 5.7C or salinities greater than 35.9 entails a slight extrapolation, the very small salinity dependence of pK1 and the slight curvature of pK1 vs T-1 indicate that equation 14 can be reliably used between 0C and 35C and at salinities between 33 and 37 This contention is supported in part by the pK1 determinations of Sendroy and Rodkey (1961) in 0.15 M NaCl at 25C and 37C. Their result, L\pK1 = pK 1 (25C) -pK1 (37C) = 0.095 0.012, can be compared with the result, L\pK1 = 0 100, calculated by extrapolating equation 10 to 37C.

PAGE 39

In spectrophotometric pH determinations using equations 7 and 14, it is important that the parameter >..Amax is accurately assessed. Analyses indicated that, in aqueous media, sssAmax exhibits very little, if any, dependence on medium composition Consequently, sssAmax can be conveniently determined at a given temperature through measurements in either seawater or NaCl. Additions of phenol red stock medium to 0 7 M NaCl media at pH 1 8 11.0 allow direct determination of sssAmax As an alternative, phenol red can be added to seawater at high pH and equation 7 and 14 can be used to calculate sssAmax In either case, it is, of course, important that dilutions of the phenol red stock medium are well defined. Examination of sssAmin supports the contention (Sendroy and Rodkey, 1961) that sssAmin can generally be set equal to zero in equation 7. Differences between pH determinations which use the approximation sssAmin = 0 and determinations using the more refined estimate, sssAmin/ sssAmax = 1.2 x 10-3, are quite small Even at a pH as low as 7 .2, well outside the pH range of normal seawater, the differences between pHs calculated using sssAmin = 0 and sssAmin/ sssAmax = 1.2 x 10-3 are on the order of 0.002 pH units. Due to the relatively small salinity dependence of pK1 spectrophotometric pH determinations employing equation 7 and 14 do not require detailed salinity measurements However, in employing equation 14, it should be noted that measurements reported to 0.001 pH require temperature control to within

PAGE 40

0.1 C. Furthermore, although the temperature dependence of sssA max is very much smaller than that of pK1 it is advisable to obtain sssAmax at the temperature used in determinations of sssA. 1 9 In addition to the procedures outlined above which requue absorbance measurements at a single wavelength, it should be noted that measurements at two or more wavelengths may offer significant advantages in some applications. The term (A.A A.Amin)/(A.Amax A.A) in equation 7 is equal to the concentration ratio, [DR]/[Dy]. Spectrophotometric measurements at two or more wavelengths permit direct calculation of the ratio [DR]/[Dy] through examination of spectral shape (A.A vs. wavelength) rather than comparison of ,.,A and A.Amax In a multi wavelength analysis, the concentrations [DR] and [Dy] and their ratio can be calculated by using equations of the form at two or more wavelengths simultaneously (Byrne et al., 1981 ). In the case that only two wavelengths are used in an analysis of phenol red spectra, particularly appropriate choices are 558 nm, the A.ER molar absorptivity maximum, and 433 nm, the A.EY molar absorptivity maximum. In this case, the ratio [DR]/[Dy] is given as where R = sssA/433A. Co= 558EY/433Ey, cl = 558ER/433Ey and c2 = 433ER/433Ey Since all of the terms on the right hand side of equation

PAGE 41

20 16 involve absorbance ratios, or molar absorptivity ratios appropriate to yellow 6.EY) and red (A.ER) forms of dye, measurement of pH is rendered independent of dye concentration and path length. Summary of spectrophotometric determination of seawater llll Spectrophotometric methods add considerable versatility to the determination of seawater pH. Convenience of measurement in closed systems, sensitivity, and rapid response are important general attributes of spectrophotometric pH determinations. Rapid response is of special significance when rapid data acquisition is important The general attributes of spectrophotometric pH determinations appear particularly well suited to the in situ examination of fine structure in ocean pH profiles, and to examination of kinetic processes that result in changes in alkalinity

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2 1 OXIDATION RATE EXPERIMENTS Introduction In these investigations, oxidation/dissolution rates of marcasite and pyrite are examined under controlled laboratory conditions The effect of changes in medium compo s ition temperature pressure, and dissolved oxygen concentration are examined through measurements of total iron evolved during oxidation/dissolution. This work constitutes the first comparison of marcasite and pyrite oxidation/dissolution rate obtained either in seawater and/or at high hydrostatic pressure. Experimental Samples Pyrite and marcasite samples which were used in the oxidation rate determinations were obtained from Wards Scientific Company. X-ray powder diffraction patterns (Norelco Recording D i ffractometer) indicated that the samples were not contaminated with other minerals Pyrite, from the United States Geological Survey (U.S.G.S ) (sample numbers 79SK002 and TA38-148), was used for the trial and control experiments.

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Sample preparation Preparation of mineral samples for the oxidation rate experiments followed these steps : 1. Pure mineral was ground in a boron carbide mortar and pestle 2. The ground mineral samples were partitioned through nytex sieves into a 20 to 53 Jlm fraction 22 3. The sieved materials were placed m a methanol/deionized water solution and subjected to ultrasound treatment for 15 minutes. Subsequently, the supernatant was discarded. 4. Mineral samples were dried and stored until use. 5. Prior to each experiment, mineral samples were stored for twenty four hours or longer in the type of solution which was to be used in the subsequent oxidation rate measurements 6. Immediately before each experiment, oxidation products were removed from the surface of the mineral samples by carefully rinsing 3 times with 3 N HCl, followed by rinses with deionized water, and a final rinse of ethanol or methanol. Step 3 in the mineral sample preparation effected the removal of "fines" which would otherwise increase the initial oxidation rate and produce variable surface areas. Fines are small particles coated on larger particles, an artifact of crushing/grinding the mineral sample (Holdren and Berner, 1979).

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23 Figure 2 Pyrite treated with ultrasound and acid washed

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24 Figure 3 Pyrite acid washed

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25 Figure 4 Pyrite incubated 6 days and acid washed

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26 A control experiment was conducted in order to determine the best way to remove fines Three pyrite samples (53-1 02 Jlm fraction) were subjected to various treatments. 1. The first sample was washed as described above (with 3 N HCI, followed by deionized water and methanol). 2. The second sample was placed into a beaker with a mixture of ethanol (or methanol) and deionized water, and the suspension was subjected to ultrasound for 15 minutes. The supernatant was decanted away and the residue was saved and washed with 3N HCl as above. 3. The third sample was incubated in seawater for 6 days in an attempt to allow all fines to dissolve. Following incubation, this sample was also washed with 3 N HCl as above. Photomicrographs were taken of all of the pyrite samples with an International Scientific Instruments DS-130 scanning electron microscope. It was found that the second sample (Figure 2) which had been treated with ultrasound was free from fines; the first sample (Figure 3) and the third sample (Figure 4) were still coated with fines. Ultrasound treatment was thereafter part of sample preparation. It was also noted that the edges on the mineral surface were showing signs of dissolution. An experiment to ascertain the effect of removal of fines on the oxidation rate of pyrite was performed (see Appendix 1). Removal of fines resulted in a rate that was 23% lower. The treated samples also show less variability, as expected.

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27 Smoothing of edges It was expected that particles formed by crushing and grinding would be more likely to have a greater number of "edges" than those precipitated in-situ in the ocean. Step 5 in the preparation of the mineral samples was performed in order to smooth out any edges which may have been an artifact of sample preparation. Edges were of concern because other investigators have considered fractures and edges to be the centers of oxidation. In viewing pyrite after oxidation, Goldhaber (1983) noted that there was more extensive oxidation taking place along fractures and other sites of strain. McKibben and Barnes (1986) have suggested that the surface area and the reactive surface may not be synonymous. Use of a strongly oxidizing acid has been suggested as a remedy for this problem However McKibben and Barnes (1986) point out that the use of an oxidizing acid may itself cause pitting, thereby defeating its purpose The significance of these "edge effects" has been questioned by Nicholson et al. ( 1988). Their samples were not annealed with a strongly oxidizing acid, and they found that the reactive area of pyrite is at least proportional to its surface area. For this purpose, a measure of near in-situ oxidation rates, preincubation of the mineral seemed the best approximation of nature Removal of pre-experiment oxidation products Step 6 in the preparation of the mineral samples cleaned the sample of any oxidation products which may have formed during sample processing and storage Goldhaber (1983) noted more consistent results with more extensive pyrite cleaning Moses et al.

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28 (1987), in examining the effect of various methods of preparation on the rate of pyrite oxidation, found that there was essentially no difference in dissolution rates of cleaned samples whether stored under nitrogen or stored in air. They concluded that coatings of oxidation products on mineral samples were not formed after cleaning but were a product of inadequate cleaning of the mineral. Diligent efforts were made to remove oxidation products from the sample before each experiment. It was found that cleaning pyrite samples with 3 N HCI reduced the iron detected on washed pyrite by an order of magnitude compared to unwashed pyrite (see Appendix I). Experimental Conditions Mineral samples were incubated under the following five sets of conditions: 1. 0 7 M NaCl with borate/boric acid buffer (3.0 x J0-4 M total boron), 25 C, I bar and 1.0 x I0-3 moles 02/liter. 2. Salinity 34.5 carbonate free seawater with borate/boric acid buffer (1.2 x I0-3 M total boron), 25 C, I bar, and 1.0 x I03 moles 02/liter. 3. Salinity 34.5 carbonate-free seawater with borate/boric acid buffer (1.2 x I0-3 M total boron), 25C, I bar, and 7.0 x I05 moles 02/liter. 4. Salinity 34.5 carbonate-free seawater with borate/boric acid buffer (1.2 x I0-3 M total boron), 0-2 C, I bar, and 7.0 x I05 moles 02/liter.

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29 5. Salinity 35.6 seawater (no added borate), 3.3C, 207 bars and 7 0 x 10-5 moles 02/li ter. Solutions used in studies 1-4 also contained ca 1 x 10-6 moles/liter of phenol red pH indicator dye (Eastman Kodak) which was added for the spectrophotometric pH measurements. (The presence of phenol red m the solution did not interfere with absorbance measurements at 593 nm performed during the iron analysis. Under acidic conditions, phenol red absorbs only at ca. 433 nm.) Experimental Procedure The following general procedure was employed for all experiments: 1. Seawater or 0.7 M NaCl solution was saturated with the appropriate oxygen concentration and the pH was adjusted with either sodium hydroxide or hydrochloric acid. 2. Solutions were added to each weighed mineral sample (average mineral concentration for studies 1 -4 = 0.001 moles/liter solution and for study 5 = 0.007 moles/liter solution). Mineral samples were weighed to 6 places on a Mettler balance. 3. To ensure minimal changes in oxygen concentration all solutions were bubbled with the appropriate gas (oxygen or oxygen/nitrogen mixture) as they were added to the incubation vessels Incubation vessels were filled to capacity 4. After sealing the incubation vessel the samples were treated with ultrasound to ensure wetting of the mineral suspensions

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5. The majority of the samples (test samples) were immediately incubated under controlled conditions and, at the end of the incubation period, processed and analyzed for iron. 30 6. The remaining samples (mineral blanks) were not incubated. They were instead immediately processed and analyzed for iron in exactly the same manner as the test samples. In this manner, any uon on mineral samples which was not removed by cleaning with acid was accounted for. Several mineral blanks were included with each experiment. The mean value of the mineral blanks for each study is presented in Table 61 Appendix 5 7. Blanks (no mineral) were also included in th e experiments. pH measurements Measurements of pH for studies 1-4, were determined spectrophotometrically (Robert-Baldo et al., 1985 ) u s ing a DMS-90 spectrophotometer. In study 5, initial pH was mea s ured with a Ross combination pH electrode. Seawater pH was expres se d in terms of free hydrogen ion concentrations (Ramette et al, 1 977). For spectrophotometric pH measurements in 0 7 M NaCl, it was assumed that the pK of phenol red was the same as that of S = 34. 5 seawater. Laboratory studies confirmed this assumption within 0.02 pH units No attempt was made to control the pH of the mineral suspensions during the course of an experiment. Solution pH decreased within a range of ca. 0.2 to 0 005 pH units, but most experiments showed an average decrease of ca. 0 0 4 pH units a s the oxidation reaction progressed.

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3 1 Experiments at 1 atmosphere pressure The reaction chambers for all experiments performed at 1 bar (studies 1-4) were 10 em glass cells (ca. 30 cm3 capacity) sealed with Teflon stoppers and covered with Parafilm. The incubation time for studies 1 and 2 conducted at 25C in oxygen saturated 0.7 M NaCI and seawater at 25C, was 5 8 hours For study 3, conducted at 25C in seawater with an oxygen concentration of 7 x 10 5 moles/liter, the incubation time was increased to a period of 16 to 26 hours The tests in study 4, incubated at 0.5C in seawater with an oxygen concentration equal to 7 x 10-5 moles/liter, were conducted for 22 to 72 hours. Mechanical rocking of the thermostated cells (ca. 16 cycles/min) gently agitated the mineral suspensions. Experiments conducted at 2 07 bars For experiments conducted at high pressure (study 5), Cole Parmer filmware 3 cm3 capacity tubes were employed as incubation vessels. The tubes containing the mineral suspensiOns were heat sealed and were further sheathed in larger 10 cm3 capacity filmware tubes which were also heat sealed. High pressure experiments were conducted for 24 to 96 hours at temperatures of 3.3 0.4oC and pressures of 3000 23 lb/in2 (206.9 1 6 bars) m a thermoregulated pressure chamber. Mechanical rocking of the pressure chamber (ca. 16 cycles/min) agitated the mineral suspensions. initial Experiments

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32 Hydrous ferric oxides (produced by FeS2 oxidative dissolution) are highly insoluble under mildly alkaline conditions (Kester et al., 1975; Byrne and Kester, 1976) In preliminary experiments at near neutral pH pyrite was placed in seawater (or 0.7 M NaCl) and attempts were made to follow changes in evolved (oxidized) iron through time in a single reaction vessel. The observations suggested that essentially all the iron formed during pyrite oxidation is adsorbed on the sides of the reaction vessel or mineral surfaces. No increase in iron was found in aliquots of solution which were withdrawn and directly analyzed for iron over a period of five hours. When pyrite was incubated in 0.7 M NaCl over a longer period (>90 hours), only a small increase in total iron was observed (see Appendix 2). Comparison of iron and sulfate measurements indicated a ca. 300 fold deficit of iron with respect to sulfate. Although the sulfate measurements were considered unreliable these results implied that iron was adsorbing onto available surfaces These types of experiments were discontinued in favor of experiments with several reaction vessels which could be treated to solubilize any adsorbed iron After treatment to solubilize iron, oxidation rates were determined to be an order of magnitude greater than rates determined without solubilization Further control experiments demonstrated that the acidification treatments were sufficient to recover iron standards which had been added to seawater and incubated for several days (see Appendix 3 ). Preparation for iron analysis

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33 Precipitated and adsorbed iron in these experiments was solubilized by treatment with hot acid. For all incubations conducted in glass cells, a 5 ml portion of the solution was carefully removed from each cell, prior to acidification, to allow for addition of acid and expanswn during heating. Concentrated hydrochloric acid was added to these cells (resulting hydrogen ion concentration = 0.5 N). Suspensions in the filmware tubes were acidified by placing each inner tube in a beaker containing ca. 100 mls of 0 5 N HCl and slitting it open. The cell (or beaker containing the filmware tube) was subsequently heated to = 70 5 C for approximately 30 minutes. This procedure was used on all test samples immediately after incubation and on mineral blanks immediately after combining solutions and minerals. Subsequent to heating, the solutions were cooled for 20 minutes and analyzed for Iron. The iron analysis method followed the methods of Collins et al. (1959 ). Reagents used for analysis of iron in pyrite and marcasite oxidation experiments. The iron analyses reagents were prepared according to Collins et al. (1959) with some modification Measurement made with these reagents exhibited good linearity and reproducibility. These data are shown in Appendix 2 1. TPTZ (2,4,6 tripyridyl-s-triazine) (Mallinckrodt AR) was added to acidified deionized water (ca. 25 drops of concentrated HCl in ca. 100.0 mls of deionized water) to form a 10-3M solution when filled to the mark with deionized water in a liter flask (Ultrasound

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34 treatment was needed to dissolve and keep the TPTZ in solution ) This 10-3M stock solution was diluted with deionized water to 104 M concentrations which were used for the iron determinations. 2 The 10% NH20HHCl, hydroxylamine hydrochloride, solution (Mallinckrodt AR.) was prepared by addition of 100 0 g of NH20HHCl to 900.0 g of deionized water For the majority of the iron analyses, it was necessary to clean the hydroxylamine hydrochloride solution. This was accomplished by addition of 50 to 100 mls of I0-3 M TPTZ solution to the hydroxylamine hydrochloride solution and extracting with ca. 50 mls nitrobenzene (Baker reagent grade) to which ca. 1 g of sodium perchlorate (Fisher) was added The emulsion formed by the organic and aqueous phase, required 24 hours to separate. The aqueous phase (with hydroxylamine hydrochloride) was retained and used in the iron determinations. 3. The acetate buffer used in the iron determinations was prepared by dissolving 328 g of sodium acetate (Fisher ACS certified) and 230 mls of acetic acid (Mallinckrodt reagent grade) in a 2 liter flask brought to the mark with deionized water to form a 2 M acetic acid/ sodium acetate solution. Iron standard preparation Two iron stock solutions that were used for the mineral oxidation experiments were made by dissolving Fe(NH4)2(S04h, ferrous ammonium sulfate (Mallinckrodt ACS reagent), in 0.5 N HCl to form 1.2 x 10-3 and 0 8 x 10-3 moles/kg solutions The iron stock

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35 solutions were diluted with 0 5 N HCl solution to form solutions of 3.0 x 10 6 to 8 0 x 10-6 mole s /kg. The standards were prepared in 0 5 N HCl in order to approach the pH of the pyrite and m a rcasite oxidati on experiment test solutions which were acidified after incubation. Iron Analysis Five mls of the acidified solution was added to 15 0 mls of 2.0 M acetate buffer and 10 0 mls of 10-4 M 2 4 ,6-tripyridyl-s-triazine (TPTZ ) solution This was followed by an addition of 5.0 mls of 10 % hydroxylamine hydrochloride (NH20H HCl), in order to reduce all ferric iron. Absorbances were measured with a Cary 17D spectrophotometer. Iron standards with concentrations between 3 x 106 to 8 x 10-6 moles/kg were analyzed in the same manner as samples and blank solutions To correct for any iron contributed by reagents or initially present on the surface of the mineral prior to oxidation, the average of the mineral blank results for each experiment was subtracted from the test result. All dissolution rate measurements are expressed m un i ts of Jlmoles F etotaii m 2 F e S 2/h r. Glassware cleansing Due to the ubiquitous nature of iron, great care wa s taken with the cleaning of glassware All glassware was soaked for at least 48 hours in 3 N HCl, rinsed with 3 N HCl and rinsed copiously with

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36 deionized water. Any glassware to be subjected to hot acid treatments during the course of an experiment was further cleaned by additional boiling (1 hour) in 6 N HCl. Particular attention was paid to incubation cells which were re-used. The cells and their Teflon caps were thoroughly rinsed, then soaked in 3 4 N HCl, followed by boiling in 6 N HCl for 1 hour, followed by copious rinsing in deionized water and subsequent soaking in deionized water for 72 hours. The Teflon caps were additionally boiled for 15 minutes in 25% nitric acid and were subsequently soaked for 24 hours in 25% nitric acid. The filmware tubes, which could be used only once, were housed in clean disposable vials as mineral and media were combined A Plexiglass box with a plastic shield was used to hold the vials and protect the tubes from contamination. Surface Area Analyses BET analyses, determination of the specific surface area of mineral samples by physical adsorption of krypton were conducted by Micromeritics, Material Analysis Laboratory of Georgia. A five point BET surface analysis by the static volumetric method was performed using an automatic Digisorb 2600. The specific surface area of the pyrite sample was 0.1338 0.021 m 2 /g and for marcasite, the specific surface area was 0 3509 0.025 m2f g Results and Discussion The marcasite and pyrite oxidation rate results obtained in this work are shown in Tables 3 and 4. Marcasite study 4 and pyrite

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37 study 1 had highly aberrant data points m each case approximately 3.3 standard deviations from the experimental mean These data points were removed from the Table 3 and 4 results. The results calculated including the outlying data are 0.42 0.18 Jlmoles/m2/hr (marcasite study 4) and 14 7 4 14 J.Lmolesfm2fhr (pyrite study 1). Table 5 presents the Tables 3 and 4 results in terms of oxidation rate ratios. For both pyrite and marcasite, Table 5 shows ratios between the oxidation rate obtained in a given study and the rate determined in the succeeding study: R = [oxidation rate (study n)]/oxidation rate (study n+1)]. Thus, Table 5 exhibits oxidation rate changes attributable to stepwise variations in solution conditions. In examining Table 5, the largest and most significant effect on oxidation rate for both minerals is seen m changing temperature from 25C to 0 5 0.2C (studies 3 and 4). With a 24.5 degree drop in temperature, the oxidation rate is decreased by a factor of 9 1 for pyrite and by a factor of 10.7 for marcasite (Table 5) The change in medium composition from 0.7 M NaCl (study 1) to seawater (study 2) had a minor influence on the oxidation rate of both minerals The oxidation rate of marcasite is 1.2 times faster in 0.7 M NaCl than m seawater. For pyrite the oxidation rate is 1.6 times faster in 0.7 M NaCl than in seawater. A nearly 10 fold decrease in dissolved oxygen concentration, from 1.0 x 10-3 moles 02 /liter (study 2) to 7 x 10 5 moles 02/liter (study 3) resulted in a decrease in the oxidation rate of pyrite by a factor of 1 7 and a decrease in the oxidation rate of marcasite by a factor of 1.9 The increase in hydrostatic pressure

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Table 3 Marcasite Oxidation Rates Experimental Conditions 1. 0.7M NaCI 1.0 x 10-3 moles 02/l 1 bar 25C pHc 7 .83 0 05 2. Seawater 1.0 x 10-3 moles 02!1 1 bar 25C pHc 7.55 0.19 3. Seawater 7.0 x 10-s moles 02/ I 1 bar 25C pHc 8.12 0 03 4. Seawater 7 .0 x 10-5 moles 02/l 1 b ar 0.5 0.2C pHc 8.04 0.16 5. Seawater 7.0 x 10-5 moles 02/l 207 bars 3.3 0.4C pRe 8.37 0.20 a. j.lmoles Fe101adm 2FeS2. b. Number of test samples. 6.58 0.98 5.50 1.02 2.88 0.30 0.27 0.10d 0.37 0.03 1 1 1 5 1 7 1 7 25 c. Free [H+ ] scale at experimental temperatur e and pressure d Rate (corrected to 3.3 0.4C) = 0.33 0.13 j.lmoles Fe1otaiim 2 F e S 2 /h r. 38

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Table 4 Pyrite Oxidation Rates Experimental Conditions 1. 0.7 M NaCI 1.0 x 10-3 moles 02/l 1 bar 25C pHc 7.85 0.11 2. Seawater 1 0 x I 0 3 moles 02!1 1 bar 25C pHc 7.73 O.I1 3. Seawater 7.0 x l0-5 moles 02 / I 1 bar 25C pHc 8 06 0 09 4. Seawater 7 0 x 10-5 moles 02/l 1 bar 0.5 0.2C pHc 8 35 0.14 5. Seawater 7.0 x 10-5 moles 02/l 207 bars 3.3 0.4C pHc 8.37 O.I4 a. Jlmoles Fetota1/m 2 FeS2. b. Number of test samples. I0.8 2.0 6.86 0.91 4.02 0 92 0.44 0.12d 0.40 0.05 I 0 1 3 I 6 20 33 c. Free [H+] scale at experimental temperature and pressure. d. Rate (corrected to 3.3 0.4C) = 0.54 0.16 Jlmoles Fe101adm 2FeS 2/hr. 39

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40 Table 5 Influence of Solution Variables on Marcasite and Pyrite Oxidation Rates Studies Variable Oxidation Rate Ratio Marcasite Pyrite 1/2 medium 1.20 0 .28 1.57 0.36 2/3 02 concentration 1.91 0.41 1.71 0.45 3/4 temperature 10.67 4 10 9.14 3.25 4/5 pressure 0 73 0.28 1.10 0.33 Table 6 Comparison of Pyrite and Marcasite Oxidation Rates Study Pyrite rate/Marcasite rate 1 0.7 M NaCl 1.64 0 39 2. Seawatera 1.25 0.70 3. Seawater (reduced 02) 1.40 0.80 4. Seawater (reduced t empe r atu re) 1.63 1.30 5 Seawater (elevated pressure) 1.08 0.49 Average 1.40 0.40 a 1 x IQ-3 moles 02/liter, S = 34.5, 25C, 1 bar total pre ss ure

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41 from 1 bar (study 4) to 207 bars (study 5) resulted m a decrease of oxidation rate for marcasite by a factor of 0 73 and an increase in oxidation rate for pyrite by a factor of 1.1 0. An Arrhenius activation energy (EA) can be calculated from the results of studies 3 and 4 us i ng the following equation (see, for example Daniels and Alberty, 1955): (17) log(k1/k2) = (EA/2 303R)(T1-T2)(T1T2)-I Where k1 and k2 are respective oxidation rates at temperatures T1 and T2 (kelvin) and R = 8 .31 joules mole-IK0-I. For pyrite, the activation energy is 61 23 kJ/mole and for m a rcasite, it is slightly lower: 49 25 kJ/mole Wiersma and Rimstidt (1984) determined an energy of activation of 92 kJ/mole for pyrite oxidation in acid ferric chloride solutions. Nicholson et al. (1988) recently obtained a value of 88 kJ/mole for pyrite oxidized under neutral and slightly alkaline conditions. The value for pyrite falls within the range of activation energies for pyrite (39 to 88 kJ/mole) reported in Lowson's 1982 r eview of pyrite oxidation and, in view of the standard error, is in re a sonable agreement with the works of Wiersma and Rimstidt (1984) and Nicholson et al. (1988). Table 6 provides a direct companson of marcasite and pyrite oxidation rates. The ratio (marcasite rate/pyrite rate) Is shown for each of the five studies. The oxidat i on rates of pyrite are all slightly higher than those of marcasite The greatest differences between the

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42 minerals are seen in study 1 (0.7 M NaCl) and in study 4 (low temperature), where pyrite oxidation rates are almost twice those of marcasite In the fifth experiment, under conditions most similar to those found in-situ on the Juan de Fuca Ridge, the oxidation rates of the two minerals are approximately equal. The average of the ratios obtained in the studies (1.4 0.4) is consistent with the generalization that pyrite and marcasite oxidation rates are quite similar. Previous comments on the relative oxidation rates of pyrite and marcasite are in apparent conflict. Wiersma and Rimstidt (1984) determined that hydrothermal pyrite was slightly more reactive (ca. 1.7 times) than hydrothermal marcasite in low ionic strength, acidic ferric chloride solutions. Pugh et al. ( 1984) noted that the oxidation rates for marcasite are much faster than those for equ i valent (surface area) amounts of pyrite under acidic conditions. Varied results have also been reported when mineral replacement has been examined in rock samples. Mathews and Robins (1974) found no difference in the ratios of the two minerals in coal, before and after oxidation of "coal pyrite" under acidic conditions Goldhaber (1983) observed that marcasite was more significantly replaced by oxides than pyrite m grains which contained both minerals. This scatter of data seems to support the conclusion that the two minerals exhibit only small differences in oxidation rates Other investigators (Warren, 1956; McKay and Halpern 1958; Mathews and Robins, 1974; McKibben and Barnes, 1987 ; Nicholson et

PAGE 64

43 al. 1988) have calculated reaction order with respect to oxygen by linear regression analyses of log oxidation rate against log oxygen concentration. Their results vary from fractional to first order with respect to oxygen (0 5 to 1 ). Plots of my results yield slopes of 0.20 for pyrite and 0.24 for marcasite, also fractional order. However, Nicholson et al., (1988) determined with five different oxygen concentrations that the oxygen dependency of the rate of pyrite oxidation (under alkaline conditions, 3-25C) was non-linear and their log-log plot was non-linear. They suggested that the discrepancy between experimenters on reaction order for oxygen ts due to assuming a rate-order and not considering an adsorption model. Additional data, over a range of oxygen concentrations, would be required to address this issue The average initial pH for all the marcasite experiments was 8.00 0.30 and for all the pyrite experiments it was 8.09 0.28. For completeness, the effect of initial pH on the individual oxidation rates determined for each set of experiments was examined. However, it should be noted that in view of the small range for initial pH (Tables 3 and 4 ), these experiments were not designed to explore this influence. No clear trend was found for pyrite, and a slight trend, increasing oxidation rate with higher pH, for the marcasite. These observations are m qualitative agreement with previous work. Smith et al. (1968) and Moses et al. (1987) previously observed small increases in pyrite oxidation rate with increasing initial pH, and Goldhaber's data (1983) showed an order of magnitude increase in

PAGE 65

44 rate between pH 6 to 9. (Under very low pH, the rate of pyrite oxidation is pH independent (Lawson, 1982; Nordstrom, 1982)). I previously examined the oxidative/dissolution rates of pyrite and marcasite (20 to 53 Jlm) in the laboratory under conditions similar to study 1 (0.7 M NaCl, 25C, 1 bar pressure, 1.0 x 10-3 moles 0 2/liter and 8.3 pH 8 6) (Feely et al., 1987). However, the surface specific oxidation rates of these samples were unknown because the samples were not analyzed for surface area, nor were they treated for removal of fines. Using the specific surface areas determined in the current work earlier results are expressed m terms of estimated surface area: pyrite oxidation rate = 24 11 Jlmoles Fe1otaiim2 FeS2/hr and marcasite oxidation rate = 34 14 Jlmoles Fe101aJim2 FeS2/hr. These rates are more than double those of this current study and, in contrast to the present observation, the oxidation rate of marcasite is 1.4 times higher than that of pyrite. The faster rates for both minerals are probably due to the presence of fines on these samples. As discussed above, it is also possible that a higher initial pH (0.3 to 0 6 pH units) in this earlier work exerted some influence on these results. As an example of the usefulness of this data in modeling effects of hydrothermal vent plumes, the oxidation rates determined for macasite and pyrite in study 5, conditions most similar to those found in-situ near the Juan de Fuca Ridge, were used to estimate the time for complete dissolution of various particles sizes The assumption was made that the particles are spherical and the

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45 dissolution rate per unit surface area does not change with surface area. The model demonstrates a linear relationship between particle diameter and time for complete dissolution The dissolution time (days) for marcasite particles is equal to the product of diameter of the particle (microns) and 2.82. For pyrite particles, the dissolution time (days) can be calculated from the product of the diameter (microns) and 2.17. The derivation of these results is presented m Appendix 9. Summary of oxidation rate experiments In general, the oxidation/dissolution rates of pyrite and marcasite change in a similar fashion as solution composition, temperature, dissolved oxygen concentration and hydrostatic pressure are varied. In seawater, temperature has a large influence on pyrite and marcasite oxidation rates. Conditions such as oxygen concentration and solution composition appear to have a secondary influence on oxidation rates. Hydrostatic pressure changes had little influence on the oxidation rates of either mineral over the range of pressures employed in our experiments. These laboratory results indicate that over a wide range of ambient conditions the comparative oxidation rates of marcasite and pyrite in seawater are quite similar and that comparative observations of relative abundances of marcasite and pyrite in hydrothermal areas will not be helpful in dating hydrothermal vent sites.

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46 SPECTROPHOTOMETRIC DETERMINATION OF HYDROGEN ION EVOLUTION DURING PYRITE AND MARCASITE OXIDATION Introduction The evolution of protons during pyrite and marcasite oxid a tion has been monitored spectrophotometrically in experiments described in this chapter. These experiments were performed concurrently with the oxidation rate experiments, described in the preceding chapter. Measurement of two different rea ction products can allow assessment of any differences in reaction pathways between marcasite and pyrite oxidation, and determination of the influence of solution variables on sulfur oxidation pathways during oxidative dissolution. Pyrite oxidation, which has been discussed in the literature more than marcasite oxidation, involves a complex series of reactions that vary with solution conditions. It is reasonable to assume that equations describing the oxidation of pyrite can also describe reactions for marcasite oxidation The following equations (18 and 19) have been cited in descriptions of pyrite oxidation which yield sulfate as a product.

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(18) FeS2 + 14Fe3+ + 8H2 0 = 15Fe2+ + 2S042+ 16H+ (Garrels and Thompson, 1960) (19) FeS2 + 7/202 + H20 = Fe2+ + 2S042+ 2H+ (Singer and Stumm, 1969). 47 It is not clear what the oxidizing agent for marcasite and pyrite will be in seawater under the conditions of these studies. It was generally thought that oxidation by oxygen would occur at higher pH values and oxidation by ferric iron would occur under acidic conditions (Singer and Stumm, 1970). However, Moses et al. (1987) postulated that ferric iron is the major oxidant even under neutral or alkaline conditions where ferric iron is very insoluble. Therefore, this discussion will include the two most likely oxidants, ferric iron and oxygen. Some investigators have found that element a l sulfur can also be produced by FeS 2 oxidation (McKay and Halpern, 1958; Bailey and Peters, 1976) Oxidation by oxygen or by the electrochemical mechanism suggested by Bailey and Peters (1976) can be described by the following equation: Oxidation of FeS2 by ferric Iron (equation 21) h as been suggested by Hiskey and Schlitt (1982).

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48 (21) FeS 2 + 2Fe3+ = 3Fe2+ + 2S0 In seawater (slightly alkaline pH), the ferrous iron will be quickly oxidized and ferric hydroxy complexes will form (Byrne and Kester, 1976; Kester et al., 1976). (22) Fe2+ + l/402 + H+ = 1/2H 2 0 + Fe3+ (23) Fe3+ + 3H20 = Fe(OH)3 + 3H+ Therefore, the overall equation for FeS2 oxidation, resulting in production of sulfate or sulfur must incorporate reactions 22 and 23. Equations 18, 22 and 23 as well as equations 19, 22 and 23 can be written as: If elemental sulfur is the product and oxygen is the oxidant (equations 20, 22 and 23), or when ferric iron is the oxidant and is regenerated by reaction 22 (equations 21, 22 and 23 ) the following equation results : (25) FeS 2 + 3/402 + 3/2H20 = Fe(OH)3 + 2S0

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Thus, when the oxidation product of pyritic sulfur is sulfate, the H +{Fe ratio is equal to four (equation 24 ) ; and when the product IS elemental sulfur, the H+ /Fe ratio is equal to zero (reaction 25). 49 In addition to the above reactions with so and S04 2as final products, Goldhaber (1983) found three additional products of pyritic sulfur oxidation in solutions of 0 1 M KCl, pH 6 to 9, at 30C (conditions similar to the conditions in my experiments). He has proposed equations 26 through 30, with sulfate, sulfite, tetrathionate, thiosulfate and elemental sulfur as the predominant sulfur products and with lepidocrite as the iron product (Fe(OH)3 = FeOOH + H20). In these equations the expected H+ /Fe ratio ranges from 0 to 4. (30) 2FeS 2 + 1.502 + H 2 0 = 2Fe00H + 4SO Sulfite, tetrathionate and thiosulfate are understood to be metastable intermediates that appear and persist according to solution conditions. These intermediates are expected to eventually form sulfate. Elemental sulfur is fairly stable, if formed The implications

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50 from Goldhaber's results are that hydrogen ion production increases with further oxidation of the sulfur product and sulfur oxidation can produce temporal variations in the H+/Fe ratio which is expected to range from 0 to 4. Hiskey and Schlitt, (1982) noted that (except at low oxidation potentials and low pH) oxidation of elemental sulfur can sometimes occur by the following reactions : (32) so+ 4H 2 0 + 6Fe3+ = S042+ 6Fe2+ + 8H+ Reactions 21 or 25 followed by reaction 31 would result in a H+/Fe ratio of 4 Reactions 21 or 25, followed by reaction 32 would also result in a ratio of 4, since iron (III) is regenerated by reaction 22 These equations describing the the oxidation of pyrite illustrate that an overall yield of 4 to 0 moles of protons produced for every mole of pyrite oxidized is expected in seawater. The H+ /Fe ratios, as illustrated by the preceding equations will not depend whether the oxidant is oxygen or ferric iron, but will depend on the sulfur product. Determination of the H+ /Fe ratio may thereby allow insight into the sulfur products of pyrite and marcasite oxidation, and possibly indicate if the reaction pathways are the same.

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5 1 Experimental Samples of minerals were incubated in seawater (or 0.7 M NaCI) containing phenol red, and colorimetric changes were measured. The use of phenol red allowed sensitive examination of the small pH changes (Robert-Baldo et al., 1985) which accompany marcasite and pyrite dissolution. Changes in solution total alkalinity with time were used to calculate hydrogen ion evolution rates. The effect of changes in solution composition, temperature and dissolved oxygen concentration were examined. The spectrophotometric method has distinct advantages over potentiometric pH measurements in lessening contamination and noise, and increasing sensitivity. Sample preparation The mineral samples used in these studies were identical to those used in the studies conducted through the measurement of total iron evolution. The mineral samples were prepared as described in the preceding chapter. Experimental Conditions Hydrogen ion evolution rates were determined spectrophotometrically (in addition to the oxidation rate determinations by total iron measurements) in the first four studies described in the preceding chapter. These studies were performed under the following conditions: 1. 0.7 M NaCl with borate/boric acid buffer (3.0 x 10-4 M total boron), 25C, 1 bar, and 1.0 x 10-3 moles 02/liter.

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2. Salinity 34.5 carbonate-free seawater with borate/boric acid buffer (1.2 x 10-3M total boron), 25 C, 1 bar, and 1.0 x 10-3 moles 0 2/liter. (Seawater was purged of carbonates to allow the small changes in pH to be detected (see Appendix 6 .).) 3. Salinity 34.5 carbonate-free seawater with borate/boric acid buffer (1.2 x 10-3 M total boron), 25C, 1 bar, and 7.0 x 10-5 moles 02/liter. 4. Salinity 34 5 carbonate-free seawater with borate/boric acid buffer (1.2 x 10-3M total boron), 0-2C, 1 bar, and 7 0 x 10-5 moles 02/liter. Seawater and 0.7 M NaCl solutions also contained ca. 2 x 10-6 moles/liter of phenol red pH indicator dye (Eastman Kodak ). Experiments were not performed at high hydrostatic pressure. Experimental Procedure Initial trial experiments were conducted in order to optimize the method (Appendix 6). The following general procedure was employed for all experiments. 1. Seawater or 0.7 M NaCl solution was pre-saturated with the appropriate oxygen concentration and the pH was adjusted with either sodium hydroxide or hydrochloric acid 52 2. Mineral samples were weighed to 6 places on a Mettler balance and placed inside spectrophotometric 10 em glass cells (ca. 30 cm3 capacity, sealed with Teflon stoppers) Incubation solutions were added to each weighed mineral sample (average mineral concentration = 0.001 moles/liter solution)

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53 3. To ensure minimal changes m oxygen concentration and to avoid addition of atmospheric carbon dioxide. all solutions were bubbled with the appropriate gas (oxygen or oxygen/nitrogen mixture) as they were added to the cells. Incubation vessels were filled to capacity to avoid a large air head and were immediately capped and sealed. 4. All samples were treated with ultrasound to ensure wetting of the mineral suspensions. 5. The cells were immediately placed in a temperature bath which gently agitated the mineral suspensions (ca. 16 cycles / min.). 6. In order to separate any systemic changes in pH from those caused by mineral oxidation several solution blank s were included in each experiment. (See Appendix 6 for the bl a nk measurement results.) 7. Depending on rate of oxidation. absorbance readings of the solutions were taken at intervals from 0.5 to 20 hours at wavelengths of 558 nm and 700 nm (DMS-90 spectrophotometer with a thermoregulated cell holder). 8. Studies 1 and 2 were continued for 5 to 8 hour s Because experimental conditions reduced the oxidation rate and therefore. the rate of absorbance change. studies 3 and 4 w ere incubated for longer periods of time Study 3 was incubated 1 6 to 26 hours. and study 4 was terminated after 22 to 72 hours. Glassware cleansing Since the first part of this work involved iron d e terminations, great care was taken with the cleaning of glassware Cleaning

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54 procedures are described in detail in the preceding chapter. Particular attention was paid to the incubation cells which were re used. The cells and their Teflon caps were thoroughly rinsed, then soaked in 3-4 N HCl, followed by boiling in 6 N HCl for 1 hour. The Teflon caps were additionally boiled for 15 minutes in 25% nitric acid and were subsequently soaked for 24 hours in 25% nitric acid. Acid cleaning was followed by copious rinsing in deionized water, subsequent soaking in deionized water for 72 hours and a final copious rinse with deionized water, in order to avoid contamination of the cells by acid released by the glass Surface Area Analyses Since identical samples were used in these studies and in the studies described in the preceding chapter, the specific surface areas are identical: pyrite = 0.1338 0.021 m2/g, and marcasite = 0.3509 0 025 m2/g. Total alkalinity calculation The pH determined by colorimetric measurement (Robert Baldo et al., 1985) can be used to calculate changes in each solution's total alkalinity. Changes in total alkalinity reflect changes in the hydrogen ion concentration created by the oxidative dissolution of the minerals The total alkalinity of carbonate free seawater can be expressed as: (33) TA = BT/(1 + ([H+]fKB')} + mOHmH + DT/(1 + ([H+]fKD)}

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55 Carbonate alkalinity is not included smce the seawater used for these experiments was purged of carbonates BT, total boron concentration (mole/kg), and DT, total dye concentration (mole/kg), are known quantities. The symbol, [H+], denotes the hydrogen ion molality as measured by the colorimetric method on the free hydrogen ion scale, moles/kg (Ramette et al., 1977) Kn is the apparent dissociation constant of phenol red which is a function of solution salinity and temperature (Robert-Baldo et al., 1985 ) KB' is the apparent dissociation constant for boric acid in seawater. The parameters mH and mOH are total hydrogen ion concentration and total hydroxyl ion concentration, respectively. The parameter mH IS defined as: (34) mH = [H+] + [HS04-] + [HF] m molal concentration units, whereupon, one can express total hydrogen m terms of formation constants and ion concentrations: Values for m[S04 -] and m[F-] are directly proportional to salinity. Values for and can be calculated from the following equations:

PAGE 77

56 (36) = (647.59/T) 6 3451 + (0 019085)(T) (0 5208)(1)112 in molal concentration units (Khoo et al. 1977) (37) = (-1590.2/T) + 12 .641 -(1.525)(1)11 2 in molal concentration units (Dickson and Riley, 1979) where I is the formal ionic strength The molal value for mOH is calculated using the relationship : (38) mOH = 10-(Pkw-pmH) The value for pkw m seawater is calculated as (39) pkw = (3441/T) + 2.256 (0 709)(1)1/2 m molal concentration units (Dickson and Riley, 1979) KB ', the apparent dissociation constant for boric a cid in seawater, is calculated from the following empirica l equation : ( 40) lnKB 'sws = lnKB + 0.5998 (75.25/T) ( S)l / 2 0 01767(S) m molal concentration units (Hansson 1972; Millero, 1979) KB is the thermodynamic constant in pure water, T is absolute temperature and S is salinity (parts per thousand ). KB can be calculated from the following empirical equation :

PAGE 78

57 ( 41) lnKB = 148.0248 (8966.9/T) (24.4344(ln(T))) in molal concentration units (Owen, 1934; Millero, 1979) The subscript SWS in equation 34 indicates the scale which Hansson used in which hydrogen ion concentrations are expressed in terms of total concentrations (mH), in molal units. ( 42) pHsws = -log(mH) Since all pH values were measured on the free hydrogen ion scale, KB 'sws was converted to the free hydrogen ion scale: (43) pKB '= pKB'sws + log(l + For studies conducted m 0.7M NaCl, total alkalinity is giVen by the following equation: (44) TA = BT/{1 + [H+]JKB')} + [OH-][H+] + DT/{1 + ([H+]JKD)} where [H+] is measured by the colorimetric method on the free hydrogen ion scale. BT and DT are known values. KD in 0.7 M NaCl is determined from the pK for phenol red in seawater at 25oC and salinity = 35. It is assumed that for KD, on the free hydrogen ion scale, is primarily a function of ionic strength. A value of 8.85 (molal units) was used for pKB' in 0.7 M NaCl (Baes and Mesmer, 1979) and [OH-] (molal concentration units) is calculated from :

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58 ( 45) [OH-] = 10-(Pkw-pH) The pKw in 0.7M NaCl is 13.77 (Hansson, 1973). Tables listing values of parameters used in total alkalinity calculations for the individual experiments are included in Appendix 6 Results and Discussion For each set of conditions, the average H+/Fe ratio for marcasite and for pyrite is presented in Table 7. The ratio is calculated by dividing the mean rate of hydrogen evolution by the mean oxidation rate for each study (Tables 3 and 4). The hydrogen ion evolution rates are tabulated in Appendix 6. Marcasite studies 1 and 4, and pyrite study 3, each had one outlying data point. Pyrite study 4 had two outlying data points. These data, which were greater than three standard deviations from the mean, have been omitted from calculations presented in this section The tables in Appendix 6 provide mean hydrogen ion evolution rates calculated with and without these outlying results The H+/Fe ratios presented in Table 7 for pyrite studies 2, 3 and 4 are higher than the predicted value of four, even with the standard error taken into consideration. It was also noted that the difference between the first two absorbance readings was usually greater than differences between subsequent readings (see Appendix 6). There are possible explanations for an initial faster rate. A

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59 Table 7 Marcasite and Pyrite H+/Fe Ratios Study H +/Fe (N) 1 Marcasite Pyrite 1. 0.7M NaCI 1.27 0.24 (12) 2.63 0.80 (16) 2. Seawater 5.74 1.75 (16) 6.54 1.16 (14) 3. Seawater 3.80 0.47 (19) 10 09 2 52 (20) Reduced 02 concentration 4. Seawater 6.10 2 52 (20) 11.36 3 80 (22) Reduced Temperature 1 Number of test samples m calculation of mean hydrogen ion evolution rate coating forming on the mineral as it oxidizes could slow down the oxidation rate with time. However, a coating would result in a diffusion controlled rate and would not increase the H+/Fe ratio Also the results of Nicholson et al. (1990) showed a decrease in pyrite oxidation rates after 400 hours which, they suggest, is due to a coating forming. The experiments in my studies were much shorter (72 hours maximum for study 4). Another possibility is acid leaching from the cuvet into the mineral suspension. This is not likely given the results of the solution blanks (Appendix 6) and if this were the case high ratios would be expected for all studies, not just pyrite studies 2, 3 and 4.

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60 It seems most likely that the anomalous initial absorbance changes and higher than expected H+ /Fe ratios result from preexperiment metastable oxidation products oxidizing further to generate acid but no add i tional iron. For example, oxidation of preexperimental sulfur oxidation products such as tetrathionate, thiosulfate and possibly elemental sulfur would result in the formation of excess acid. It is not possible to determine the extent of hydrogen ion evolution contributed by pre-experiment oxidation products. However, in hindsight, there are corrective measures which could have been taken. If the experiments had been allowed to continue for a longer time period, it would be expected that the effect of pre-experiment oxidation products would have been ameliorated. In addition, a senes of trial experiments with various cleaning techniques could have been conducted in order to maximize removal of metastable sulfur oxidation products. In contrast, my cleaning techniques were entirely directed toward removal of iron oxidation products. Other investigators also noted that the rates determined by analysis of sulfur products were affected by oxidation products left on the mineral prior to an experiment. To correct for these problems, Goldhaber (1983), who found anomalous amounts of sulfur in his short-term experiments (7 -48 hours), disregarded his initial data points at 7 minutes. Nicholson et al. (1988) omitted the first 48 hours (from ca. 384 hours of experiment) from calculations because of initially high sulfate concentrations.

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6 1 To partially correct for interference by pre-experiment oxidation products, my H+ /Fe ratios have been recalcul a ted with the first absorbance point omitted (Table 8). Only the first data point Table 8 H +/Fe Ratios: Calculated with first data point omitted Study H+/Fe Marcasite Pyrite 1. 0.7 M NaCI 0.98 0 18 1.50 0.40 2. Seawater 3.39 1.00 4 .79 0.86 3. Seawater 2.92 0.38 8.81 2.21 Reduced 02 concentration 4. Seawater 4 86 1.97 8 98 3 .06 Reduced Temperature was omitted because several experiments had a total of three absorbance readings.) The ratios for both minerals in Table 7 are lowered by an average of 26%; and the standard error, in most cases, is also lowered. However, the ratios in Table 8 for pyrite studies 3 and 4 are still significantly higher than four. These studies were conducted at lowered temperature and oxygen concentration. The decrease in oxygen concentration and temperature may slow down the reactions which further oxidize pre-experiment oxida tion

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intermediates, and thereby increase the length of time that these reactions would interfere with the experiment. It is possible that more of the initial data should be omitted 62 Since all the H+ /Fe ratios for marcasite (Table 8) are within the expected range of 0 to 4, these results are apparently less effected by pre-experiment oxidation products than those of pyrite There are possible explanations as to why marcasite would be less affected than pyrite. Iron oxidation rates indicate that pyrite oxidizes on the average 1.4 times faster than marcasite (Table 6); therefore, pyrite would be expected to produce more pre-experiment oxidation products. Another possibility is that the effectiveness of the cleaning process may vary according to oxidation reaction product. Pre experiment oxidation products may be easier to remove from marcasite than pyrite. This possibility would imply that the oxidation products of pyrite and marcasite are different. Both of these explanations are unlikely given the fact that omission of the first data point results in essentially the same relative decrease in H +/Fe ratios for both minerals. Given the similar reduction (26%) of each minerals' H+[Fe ratios with omission of the first absorbance, it is most likely that preexperiment sulfur oxidation products influence H+[Fe ratios of marcasite and pyrite in a similar manner. In seawater Table 8 then indicates that more protons are initially produced for every mole of pyrite oxidized than for marcasite and initial sulfur oxidation products for pyrite are more oxidized than those for marcasite In

PAGE 84

63 this case the H+ /Fe ratios for pyrite studies 2, 3 and 4 should be considered to be equal to four or less, and the H+ /Fe ratios for marcasite studies 2, 3 and 4 are lower than the H+ /Fe ratios for pyrite. Sulfur products for pyrite could possibly be sulfate and/or sulfite and oxidation products for marcasite could also include tetrathionate, thiosulfate and possibly elemental sulfur. The idea of a less oxidized sulfur product resulting from marcasite oxidation ts consistent with a simple test which can distinguish pyrite from marcasite. Pyrite and marcasite are each dissolved in heated concentrated nitric acid. Pyrite completely dissolves but marcasite decomposes to form a separate flocculate sulfur solution (consistent with a less oxidized sulfur product). Table 8 clearly indicates that the H+{Fe ratio for both minerals, determined in 0.7 M NaCl (study 1), is significantly lower than four and very different from the ratios determined for the seawater studies. This implies that for both pyrite and marcasite, the sulfur product is less oxidized in 0.7 M NaCl than in seawater and elemental sulfur is a likely oxidation product. Sulfur oxidation products are probably similar for both minerals in study 1 since the ratios of the two minerals are similar (considering the standard error). Prior to the work discussed here, the oxidative/dissolution rates of pyrite and marcasite particles (20 to 53 diameter) were examined in the laboratory under conditions which (apart from a higher pH) were similar to study 1 (0.7 M NaCl, 25C, 1 bar pressure, 1.0 x 10-3 moles 02/liter and 8.3 S pH S 8.6) (Feely et al., 1987).

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64 Although, the absolute oxidation rates of these samples are unknown because the samples were not analyzed for surface area, and because they were not treated for removal of fines, the H+ /Fe ratios for each mineral can be compared with this work. The results of the earlier work are: pyrite rate = 3.4 1.5 moles hydrogen ion per mole of pyrite oxidized and marcasite rate = 2.2 1.0 moles hydrogen ion per mole of marcasite oxidized. These results compare reasonably with the Table 7 results for study 1: pyrite = 2.6 0.8 moles hydrogen ion per mole of pyrite oxidized and marcasite = 1.3 0.2 moles hydrogen ion per mole of marcasite oxidized Table 7 with no omitted data should be used in this comparison since all data were included in my previous analyses. Summary of hydrogen ion evolution rate experiments The H+ /Fe ratio for both pyrite and marcasite mcreases significantly when the incubation medium is changed from 0 7 M NaCl to seawater. This suggests that in 0.7 M NaCl, the sulfur products resulting from pyrite and marcasite oxidation are much less oxidized than those found in seawater. Elemental sulfur is probably formed in 0.7 M NaCl fo r both minerals In seawater the sulfur oxidation products of marcasite may be less oxidized than those of pyrite and therefore may include tetrathionate thiosulfate and possibly elemental sulfur. This variation in sulfur alteration products implies a difference m oxidation reaction pathways for the two minerals in seawater.

PAGE 86

65 Spectrophotometric measurements such as these described m this chapter could constitute a convenient, simple and clean method for determining and comparing rates of mineral oxidation in seawater. Characterization of sulfur alteration products and their subsequent reactions would allow assessment of H+ /Fe ratios and conversiOn of hydrogen ion evolution rates to oxidation rates. However, my results strongly indicate that extremely clean samples are required to obviate pre-experiment oxidation problems.

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66 SUMMARY In general, the oxidation/dissolution rates deduced from iron observations indicates that pyrite and marcasite rates change in a similar fashion as solution composition, temperature, dissolved oxygen concentration and hydrostatic pressure are varied. In seawater, temperature has a large influence on pyrite and marcasite oxidation rates. Conditions such as oxygen concentration and solution composition appear to have a secondary influence on oxidation rates. Hydrostatic pressure changes had little influence on the oxidation rates of either mineral over the range of pressures employed m these experiments. Since, the comparative oxidation rates of marcasite and pyrite in seawater are quite similar over a wide range of ambient conditions, comparative observations of the relative abundances of marcasite and pyrite in hydrothermal areas will not be helpful in dating hydrothermal vent sites. The H+ /Fe ratio for both pyrite and marcasite mcreases significantly when the incubation medium is changed from 0 7 M NaCl to seawater. This implies that in 0 7 M NaCI, the sulfur products resulting from pyrite and marcasite oxidation are much less oxidized than those found in seawater. Seawater analogs such as 0.7 M NaCl

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67 should be used with caution m mineral oxidation studies appropriate to seawater. Comparison of H+ /Fe ratios for pyrite and marcasite in seawater indicate that sulfur alteration products of marcasite may be slightly less oxidized than those of pyrite and may include tetrathionate, thiosulfate and possibly elemental sulfur. These results suggest that the reaction mechanisms for sulfur oxidation for pyrite and marcasite are not identical.

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LIST OF REFERENCES Baes, C. F., Jr. and Mesmer, R. E 1976 The hydrolysis of cations, Wiley, New York. 68 Bates R. G., 1973. Determination of pH theory and practice 2nd ed. Wiley, New York. Betzer, P. R., Byrne, R. H Acker, J. G., Lewis, C. S., Jolley, R. R. and Feely, R. A., 1984. The Oceanic carbonate system: Assessment of inorganic controls, Science, 226 : 107 4-1077. Brewer, P. G., 1975. In Riley, J. P., Skirrow, G., (Editors), Chemical Oceanography 2nd. ed., Academic Press, London, Vol. 1, Chapter 7. Bruland, K W., 1983 In Riley, J. P Chester, R., (Editors) Chemical Oceanography, Academic Press, London, Vol 8, Chapter 45. Byrne, R. H. and Kester, D., 1976. Solubility of hydrous ferric oxide and iron speciation in seawater, Mar. Chern., 4 : 255-274. Byrne R. H. and Kester, D., 1978 Ultraviolet spectroscopic study of ferric hydroxide complexation, J Solution Chern., 7 : 373-383. Byrne, R. H., Young, R. W. and Miller, W. L., 1981. Lead chloride complexation using ultraviolet molar absorptivity characteristics, J Solution Chern., 10 : 243 251

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69 Byrne, R. H 1984. Absorbance corrections in self-adjusting path length-diameter, high pressure cells, Rev. Sci. Instrum., 55 : 131-132. Byrne, R. H Acker, J G Betzer, P. R Feely, R. A. and Cates, M. H 1984. Water column dissolution of aragonite in the Pacific Ocean, Nature (London) 312 : 321-326. Collins, P. F. Diehl, H. and Smith G F., 1959. 2 4,6-tripyridyl-s triazine as a reagent for iron Determination of iron in silicates, limestone and refractories, Anal. Chern 31 : 1862-1867. Culberson C. H 1981. In Whitfield, M ., Jagner, D ( Editors) Marine Electrochemistry, Wiley New York, 187 261. Dana, J D and Dana, E. S 1944. In Palanche, C., Berman, H., Frondell, C (Editors) The system of mineralogy, 7th Ed Wiley, New York, Vol 1. Daniels, F. and Alberty, R. A 1955. Physical Chemistry Fourth Edition, J Wiley & Sons, New York Dickson A G and Riley J P., 1979 The estimation of acid dissociation constants in seawater media from potentiometric titrations with strong base, Mar. Chern 7 : 89 99. Feely, R. A., Massoth, G. J Curl, H. C., Lewison Boudreau M and McMurty, G. M ., 1984 Composition of white and black smoker particulates from active vents on the Juan de Fuca and Endeavor Ridges, EOS Trans AGU 65(45) : 112 Feely R A., Lewison, M., Massoth, G J and Von Dam, K. L., 1985 Mineralogy and elemental composition of black smoker particulate s from active vents on the Southern Juan de Fuca Ridge EOS Trans AGU, 66(46) : 929

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70 Feely, R. A., Lewison, M., Massoth, G. J., Robert-Baldo, G., Lavelle, J. W., Byrne, R. H., Von Dam, K L. and Curl Jr., H. C., 1987. Composition and dissolution of black smoker particulates from active vents on the Juan de Fuca Ridge, J. of Geophys. Res., 92, B11 : 11347-11363. Garrels, R. M. and Christ, C. L., 1965. Solutions, minerals and equilibria, Harper and Row, New York. Goldhaber, M. B., 1983. Experimental study of metastable sulfur oxyanion formation during pyrite oxidation at pH 6-9 and 30 C, Am. J of Science, 283 : 193-217. Hansson, 1., 1972. An analytical approach to to the carbonate system in seawater. Ph. D. Thesis, University of Goteborg, Sweden. Hansson, I., 1973. A new set of pH scales and standard buffer for seawater, Deep Sea Res., 20 : 479-491. Haymon, R. M. and Kastner, M., 1981. Hot spring deposits on the East Pacific Rise at 21 N: preliminary description of mineralogy and genesis, Earth Planet. Sci. Lett., 53 : 363-381. Hiskey, J. B. and Schlitt, W. J., 1982 In Schlitt, W J., Hiskey, J. B., (Editors), Interfacing technologies in solution mining, Proc. 2nd SME SPE Inti. Soln. Mining Symp. Denver, Chapter 7 Holdren, Jr. G. R. and Berner, R. A., 1979 Mechanism of feldspar weathering I; Experimental studies, Geochim. Cosmochim Acta, 43 1161-1171. Hood T. A., Zika, R. G. Millero, F. J. and Blackmelder, P. L. 1988. Pyrite oxidation in seawater: Experimentally produced alteration phases, EOS Trans. AGU, 69(16) : 528.

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7 1 Kester, D., Byrne, R. H. and Liang, Y., 1975. In T. M Church (Editor.), Marine chemistry in the coastal environment, Am. Chern. Soc. Symposium Series No. 18., Chapter 3. Leinen, M., 1985. Mineralogy of hydrothermal vent precipitates within and near active vents on the Juan de Fuca and Explorer Ridges, EOS Trans AGU, 66(46) : 928. Lowson, R T., 1982. Aqueous oxidation of pyrite by molecular oxygen, Chern Rev., 82 : 461-497. Luther, G W., Meyerson, A. L., and DiAddio, A.,1978. Voltammetric methods of sulfate ion analysis in natural waters, Mar. Chern., 6 : 117-124. Marquardt, D. W. 1963. An algorithim for least-squares estimation of nonlinear paramters, J Soc. Ind Appl. Math., 11 : 431-441. Mathews, C T. and Robins, R. G., 1974 Aqueous oxidation of iron disulphide by molecular oxygen, Aust. Chern. Eng., 15 : 19-24. McKibben, M. A. and Barnes, H. L., 1986 Oxidation of pyrite in low temperature acidic solutions: Rate laws and surface textures, Geochim. Cosmochim Acta, 50 : 1509 1520. Millero, F J ., 1974 In Goldberg, E. D (Editor), The Sea Wiley New York, Vol, 5, Chapter 1. Millero, F. J ., 1979. The thermodynamics of the carbonate system m seawater, Geochim Cosmochim Acta 43 : 1651-1661. Montgomery, R. B., 1958. Water characteristics of Atlantic Ocean and World Ocean, Deep Sea Res ., 5 : 134-148

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72 Morel, F. M. M. and Morel-Laurens, N. M. L., 1983. In Wong, C. S., Boyle, E., Bruland, K. W., Burton, J. D., Goldberg, E D., (Editors), Trace metals in seawater, Plenum Press, New York, 841-869. Morris, M. J. and Byrne, R H., 1982. Spectrophotometric determination of C02 production by individual zooplankton using changes in the absorbance spectra of phenol red, EOS Trans Am. Geophys. Union, 63 (3) : 101 Morse, J W. and Berner R. C ., 1979 In Jenne, E. A., (Editor), Chemical modeling in aqueous systems, Washington, D. C A. C. S. symposium series No. 93, Chapter 24. Moses, C 0., Nordstrom, D. K Herman, J. S. and Mills, A. L., 1987 .Aqueous pyrite oxidation by dissolved oxygen and ferric ions, Geochim. Cosmochim Acta, 51 : 1561-1571. Mottl, M. J., 1983. Metabasalts, axial hot springs, and the structure of hydrothermal systems at mid-ocean ridges, Geol. Soc. of Am. Bull., 94 : 161-180. Nicholson, R. V., Gillham, R. W. and Reardon, E. J., 1988. Pyrite oxidation in carbonate-buffered solution 1 Experimental kinetics, Geochim Cosmochim. Acta, 52 : 1077-1088. Nicholson, R. V., Gillham, R. W. and Reardon, E. J ., 1990 Pyrite oxidation in carbonate-buffered solution. 2. Rate control by oxide coating, Geochim Cosmochim. Acta, 54 : 395-402. le Nobel, W. J. and Schlott, R., 1984 Truly constant diameter high pressure quartz optical cell, Rev. Sci. Instrum., 55 : 132.

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73 Nordstrom, D. K., 1982. Aqueous pyrite oxidation and the consequent formation of secondary iron minerals, In Rossner, L. R., Kittrick, J. A., Fanning, D. F., (Editors), Acid sulfate weathering, Soil Sci. of Am. Press, p. 37-56. Owen, B. B., 1934. The dissociation constant of boric acid from 10 to 50C, J. Am. Chern. Soc., 56 : 1695-1697. Pickard, G. L., and Emery, W J., 1982. Descriptive physical oceanography, Pergamon Press, 4th enlarged ed., Oxford. Pugh, C. E., Rossner, L. R. and Dixon, J. B., 1984. Oxidation rate of iron sulfides as affected by surface area, morphology, oxygen concentration and autotrophic bacteria, Soil Science, 135 (5) : 309319. Ramette, R. W., Culberson, C. H. and Bates, R. G 1977. Acid-base properties of tris(hydroxymethyl)aminomethane (Tris) buffers in seawater from 5 to 40C, Anal. Chern 49 : 867-870. Riley, J. P., and Chester, R., 1971. Introduction to Marine Chemistry, Academic Press(London) LTD., London, Chapter 6. Robert-Baldo, G., Morris, M. J. and Byrne, R H., 1985. Spectrophotometric determination of seawater pH using phenol red, Anal. Chern., 57 : 2564-2567. SAS Institute, Inc. 1982. SAS users guide: Basics, SAS Institute, Inc., Cary, N.C. Sendroy, J., Jr. and Rodkey, F. L., 1961. Apparent dissociation constant of phenol red as determined by spectrophotometry and visual colorimetry, Clin. Chern. (Winston-Salem, N. C.) 7 : 646-654

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74 Smith, E. E., Svanks, K. and Shumate, K. S 1968. Sulfide to sulfate reaction studies, 2nd Symp. Coal Mine Drainage Res., Pittsburgh, PA, 1-11. Stumm, W. and Morgan, J. J., 1981. Aquatic chemistry, 2nd ed. Wiley, New York. Sverdrup, H. U., Johnson, M. W. and Fleming, R. H., 1942. The Oceans, their physics, chemistry and general biology, Prentiss Hall, Englewood Cliffs, New Jersey. Weinberg, G. H., and Schumaker, J. A., 1974. Statistics: An intuitive approach, 3rd. ed Brooks/Cole Publishing Co., Monterey, California. Wiersma, C. L. and Rimstidt, J. D., 1984. Rates of reaction of pyrite and marcasite with ferric iron at pH 2, Geochim. Cosmochim Acta, 48 : 85-92.

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75 APPENDICES

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7 6 APPENDIX 1 Preparation of mineral samples: pre-experiment acid wash and removal of fines Removal of pre-experiment oxidation products prior to a dissolution rate experiment During a trial experiment, it was determined that pyrite oxidized extensively after exposure to au. A freshly ground pyrite sample and a 8 day old sample were each added to seawater and the resulting suspensions were immediately analyzed for iron. The freshly ground suspensiOn was found to have ten times less iron than the suspension which had been ground 8 days earlier. In a subsequent experiment, pyrite which had been ground and acid washed 8 days prior was divided into two samples. One of these samples was acid washed as follows: 1. Three copious rinses with 3 N HCI. (This strength of acid was used rather than a more acidic solution because pyrite samples were held m a nytex sieve ) 2. One copious deionized water nnse. 3 One copious rinse with acetone to aid m drying the sample. 4. Ten to five minutes of gentle heat on a sand bath to dry the sample.

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7 7 APPENDIX 1 (Continued) Both the treated and untreated samples were weighed and mixtures of TPTZ reagents after Collins et al. (1959): 15.0 mls of acetate buffer, 10.0 mls 10-4 M TPTZ solution and 5 .0 mls of hydroxylamine hydrochloride solution were added to each A blank solution of the same reagents was also prepared and used to correct for contaminant iron in the reagents. The results are shown m Table 9. Washing with 3 N HCl reduced the iron by more than a factor of t en to the levels expected for freshly ground pyrite, indicating that treatment was effective. Table 9 Comparison of iron concentrations in acid washed and unwashed pyrite/seawater suspensions Sample Pyrite (M) Washed 0.02241 Unwashed 0.01945 A593nm 0.0080 0.0938 [Fehotal 4.233 49 .35 The effect of removal of fines on oxidation rate s of p y rite Iron analyses were performed on six suspensions of pyrite and seawater which had been incubated for ca. 4 hour s Three of these samples were initially treat ed to remove fines. The other samples

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78 APPENDIX 1 (Continued) were not treated but otherwise all samples were treated in the same manner, including an acid wash as described above. The results are presented in Table I 0. Removal of fines resulted in rates that were lower by a factor of 4.7 and also show less variability, as expected. It should be noted that these rates are not corrected for any iron initially present on the sample due to pre-experiment oxidation. Table 10 Comparison of oxidation rates of pyrite samples treated and untreated for removal of fines. Sample Incubation [Fe] total 1 [Feltotal1fhr Mean time (hrs) (millimoles) (millimoles/hr) Non -treated 1 4.00 2.261 0.653 Non-treated 2 3 97 1.0 9 4 0.276 Non-treated 3 3.95 6.271 1.59 0.84 Treated 1 4 .13 0.844 0.204 Treated 2 4.12 0.459 0.111 Treated 3 4 .10 0.919 0.224 0.18 1. Normalized iron concentration 0.55 0.05

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7 9 APPENDIX 2 IRON ANALYSIS AFTER THE METHOD OF COLLINS ET AL., (1959) LINEARITY AND REPRODUCIBILITY EVALUATION Linearity of calibration measurements Three preliminary experiments were performed to ascertain the linearity of the Collins et al. (1959) procedure. A summary of the results are presented in Table 11. Linearity with iron concentrations from 0.242 to at least 29.4 J.l.M was achieved. The results of experiment 3 (Table 11) were improved when the absorbance at 750 nm (where no changes in absorbance were occurring ) was used as an internal standard to correct for baseline drift. The results were also improved by utilization of a longer pathlength cell. As a result of these findings, measurement of absorbance at 750 nm was used as an internal standard, reagent ratios of 15 TPTZ : 10 NH20H.HCl : 5 acetate buffer, and a 10.0 em pathlength cell were employed in all subsequent pyrite and marcasite oxidation experiments. Reproducibility The reproducibility of the iron analysis m ethod was determined by measuring the absorbance of five different te s ts on a 0.242 J.l.M iron standard Five mls of standard was added to 10.0 mls 10-4 M TPTZ and 15 mls acetate buffer and abs o rbance was read in a

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APPENDIX 2 (Continued) 10.0 em cell. The results are tabulated in Table 12 Absorbance measurements of blank solutions were determined at 593 nm and noise due to the instrument was estimated to be 0.0005 absorbance units. The noise due to the analytical procedure, including instrument noise, was 0.0009 absorbance units. Table 11 Linearity of Calibration Measurements 8 0 Standard Fe(NH4)2(S04)2Jl M Exp 1 A593nm1 Exp 2 A593nm 1 Exp 3 A593nm1 Exp 4 A593nm2 0.242 1.21 2.42 12.1 14.7 29.4 121. 1210 Correlation coefficient Conditions TPTZ concentration cell path length Acetate : TPTZ : sample 0.0010 0.0052 0.0333 1.9914 0.999984 Exp. 1 10-3M 1.0 em 9.3 : 5.7 : 2 0 0006 0.0020 0 .0048 0 0312 0 .3020 0.999977 Exp. 2 10-3M 1.0 em 10:5:2 0.003 7 0.0380 0.0753 0.5159 1.0424 0.999984 Exp. 3 10-4M 10.0 em 15 : 10 : 5 0 .0024 0 .0378 0 .0766 0 .5192 1 .0482 0 999991 1. The absorbance has been measured against air and blank corrected: A593nm 1 = (A593nmstd A593nmblank ) 2 The absorbance has been corrected for baseline drift error by using the absorbance at 750nm as an internal standard A593nrn2 = (A593nmstd A750nmstd) (A593nmblank A750nmblank)

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APPENDIX 2 (Continued) 8 1 Table 12 Reproducibility of Absorbance Measurements Trial No. A593nm 1 0 0045 2 0 0043 3 0 0024 4 0 0024 5 0.0028 mean 0 0033 + 0.0009

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82 APPENDIX 3 INITIAL OXIDATION RATE STUDIES Initial pyrite oxidative dissolution experiments were performed in order to determine an optimum experimental design. The pyrite samples were acid-washed prior to each experiment and placed in a glass jacketed beaker which was connected to a 25C thermoregulated waterbath The reaction med i a was either seawater (collected in the Gulf of Mexico) or 0. 7 M N aCl. The pH was monitored by a Ross combination electrode, which remained placed in the reaction media throughout the experiment Some experiments were performed in equilibration with the atmosphere others were bubbled with compressed air, or with C02-free air. Aliquots of 5 .00 mls of solution were periodically withdrawn and analyzed for iron after the method of Collins et al. (1959). Two experiments also measured changes in sulfate concentration with time as well as uon. Sulfate concentrations (G. W Luther et al., 1978) were measured with a polarographic analyzer (E. G. and G. Princeton Applied Research model 384 and SMDE model 303) Five mls of test, blank or standard solution were added to 5 0 mls of 95% ethanol and 5 0 mls of 0.019 M PbCh. Sodium sulfate solutions were used as standards at concentrations of 0.00133 M and 0.000266 M.

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APPENDIX 3 (Continued) 83 Experiment 1 A 53-20 stze fraction of United States Geological Survey (U.S.G.S.) pyrite sample #79SK002 was added at a concentration of 0 1432 g /1 seawater. The reaction beaker containing the seawater/pyrite suspension was covered and bubbled continuously with compressed air (C02 was not removed) in order to stir the suspension. The initial pH of the suspension was 8 .39 and the final pH was 8 53. Both Fe2 + and Fetotal were measured i n aliquots taken over a period of 5 hours. No change in either Fe2+ and Fetotal was detected. Experiment 2. The experiment was repeated in the same manner but with a 53 to 102 U.S.G.S.pyrite #79SK002 sample at a concentration of 0 1504 g/1 seawater. The experiment was also continued for a longer period of time The initial pH was 8.51 and the final pH was 8.26. Instead of bubbling with compressed air to stir the suspension a Teflon-coated magnetic stirrer was placed in the reaction vessel. The results are graphed in Figure 5. The amount of total iron increased with time while Fe(II) increased very slightly. Pyrite probably releases Fe(II) as it dissolves Once rele a sed into seawater, the ferrous iron rapidly oxidizes. The oxidation rate of pyrite, calculated from the change in total iron concentration, is very slow; a linear regression analysi s of the plot yields a slope of 5 8 x 10-9 moles Fe/hr.

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APPENDIX 3 (Continued) 8 4 Experiment 2 0 6 0 5 0 4 [Fe] j Fe(total) / Fe(ll) / 0 3 0 2 0 1 0 0 10 20 30 40 50 60 70 80 90 100 time (hrs) Figure 5 Initial oxidation experiment 2: Iron concentration changes with time Experiment 3 Experiment 3 monitored a pyrite concentration of 0 1339 g/1 0 7 M NaCI (Mallinckrodt AR) buffered with 8.1 x I 0-5 M sodium borate (Na2B 4 07.IO H20, MCB, ACS reagent grade ) and 2.1 x I0-3 M sodium carbonate anhydrous (NaC03,Baker analyzed reagent) The initial pH was 9.96, and the final pH was 9.45. Fe2+, Fetotai and S042were measured in aliquots taken over a period of ca. 65 hours.

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APPENDIX 3 (Continued) 8 5 The results of the iron analyses are gr a phed in Figure 6. The concentration of iron (II) varied widely (probably noise) while the concentration total iron mostly increased with time Sulfate analyses are incomplete due to problems caused by changes in reagents with time and variability in the size of the Hg drop. The m e thod was also flawed because it entailed finding a small difference between two much larger numbers. However, one result was obtained : a concentration of 2.0 x I0-4 M S04 2after 67 hours. 0.4 0.35 0.3 0.25 [Fe] 0 2 flM 0 .15 0.1 0.05 1 0 20 Experiment 3 -----30 40 50 time (hrs) Fe(total) Fe( II) () 60 70 Figure 6 Initial oxidation experiment 3: Iron concentration changes with time

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APPENDIX 3 (Continued) 8 6 Assuming an initial concentration of zero sulfate and that all of the sulfur is converted to sulfate, a rate of 1.48 x 10-6 M FeS2/hr can be compared to the rate of 6.6 x 10-9 M FeS 2/hr calculated from the total iron results. There is almost a 3 order of magnitude deficit of uon with respect to sulfate. Experiment 4 Experiment 4 employed with the same reaction media as experiment 3 and with a pyrite concentration of 0.1109 g/1. The initial pH was 9.41, and the final pH was 9.21. The results are graphed in Figure 7. The concentration of Iron (II) was less varied than in experiment 3, and again, total iron increased with time and was evidently present as mostly iron (III). The sulfate analyses were again incomplete due to noise and variable results. One data point was obtained which yielded an oxidation rate of 1.08 x I0-5 M FeS2/hr compared to a rate of 3.43 x l0-8 M FeS2/hr calculated with the iron results These rates are higher than the previous experiment ; the precision of this method is very poor. However there is still a large difference between the rates calculated by the two methods, indicating a deficit of iron with respect to sulfate.

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APPENDIX 3 (Continued) 4 5 4 3 5 3 [Fe] 2 5 2 1.5 1 0.5 0 Experiment 4 F e(total) Fe( II) 87 l+l 0 1 0 30 40 50 60 70 80 90 1 00 time (hrs) Figure 7 Initial oxidation experiment 4: Iron concentration changes with time In summary, gtven the large difference between the pyrite oxidation rates calculated by measuring iron and sulfate these initial experiments suggested that iron was probably adsorbing on to the surface of the reaction vessel and the mineral surface. A new experimental design which would allow solubilization of iron was necessary It should be noted that the rates determined in these experiments are not corrected for any iron left on the mineral surface after the acid wash. Nor were the results normalized for differences in initial pyrite concentration Fines were not removed from the samples by ultrasound treatment.

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88 APPENDIX 4 Treatment to solubilize iron oxides Trial experiments (Appendix 3) indicated that it was necessary to solubilize iron released during mineral oxidation which did not dissolve but adsorbed on to available surfaces. Two control experiments determined recovery of a known concentration of iron from a seawater solution after incubation for several days Iron recovery experiment no. 1 Five mls of ferrous ammomum hydroxide standard in 10-4 N HCl was added to 50 mls of seawater and incubated for 1,6 and 8 days. A seawater sample (with 5 mls of 10-4 N HCl added) was incubated for use as a blank. The initial pH of the blank seawater solution was determined to be pH 8 .18 and after incubation for 8 days, the pH was 8.15. To solubilize iron, seawater solutions (test and blanks) were treated prior to iron analysis as follows : 1. Acidified with 2.0 mls of concentrated hydrochloric acid. 2. Heated ca. 20 minutes to boiling. 3 Cooled to room temperature. The solutions were analyzed for total Iron after the method of Collins et al. (1959) Five mls of treated seawater solution was added to 15.0 mls of 2 M acetate buffer and 10.0 ml 10-4 M TPTZ; 5.0 mls of

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APPENDIX 4 (Continued) 8 9 10% hydroxylamine hydrochloride solution was added to 25.0 mls of this solution. The recovered total iron concentration determined, after blank correction, was compared to 7.41 x 10-7M which is the calculated concentration of Fe (II) in the seawater solutions. The results are listed in Table 13. Excess iron was probably due to contaminant iron from the environment. These experiments do show that iron released into slightly alkaline seawater, as pyrite or marcasite oxidizes, can be recovered by treatment with hot acid. Table 13 Recovery of iron standard from seawater Test dais} A593nml [Fe] measured2 Recoveri3 1 (1) 0 1804 8.70 x w-7 121.9 2 (6) 0.1560 7.43 x w-7 104.1 3a (8) 0.1591 7 68 x w-7 107 5 3b {82 0.1697 8 .19 x w-7 114.7 1. Corrected for blank and baseline drift. 2. Calculated using standard assayed on same day as test. 3. (Measured/calculated) x 100. Iron recovery experiment No 2. In a second experiment, iron concentrations of freshly prepared seawater/iron standard solutions and seawater/iron standard solutions which had been incubated for several days were compared Five ml aliquots of 5.656 x 10-5 M ferrous ammonium (%)

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APPENDIX 4 (Continued) 9 0 hydroxide iron standard in 10-4 N HCl were added to known weights of seawater, ca. 50 g. Blank solutions were also prepared with 5 mls of 10-4 N HCl in ca. 50 g of seawater. All samples were treated with 2.0 mls of cone HCl and heated to boiling for 15 minutes, either immediately or after incubation at room temperature for 2 days. After cooling treated solutions for 2 hours, iron analysis were performed after the method of Collins et al. (1959). Five mls of seawater solution was added to 10.0 mls of 10-4 M TPTZ, 15.0 mls acetate buffer and 5.0 mls of 10% hydroxylamine hydrochloride solution and absorbance of the solutions was measured at 593 nm. Two of the solutions were retested after a total of 3 hours of cooling time. The results are tabulated in Table 14. Ignoring the results from test 1, which splattered during heating, the results show that incubation in seawater for several days does not affect the recovery of iron standard. Also there is no difference between results with different cooling times and precision is good for the repeated assays These results indicate that large loss of solution during heating is likely to produce errors. The mean measured absorbance at 593 nm for tests 2, 3, 4 and 5 (0.1585) compares well with a calculated absorbance of 0 .1602 (assuming a molar absorptivity of 22600), and indicates ca. 98.9% recovery of iron.

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APPENDIX 4 (Continued) 9 1 Table 14 Comparison of iron concentration in treated seawater/iron standard solutions incubated for 0 and 48 hours Test Time of treatment (hrs) A593 nm1 1 0 0 13832 13 0 0.13832 2 0 0 1584 23 0 0 1584 3 48 0.1602 4 48 0.1579 5 48 0 1574 1. Corrected for blank, baseline drift, evaporation due to heating and any difference in amount of seawater. 2. Solution splattered while heating 3 Reassay after longer cooling period

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92 APPENDIX 5 RESULTS OF OXIDATION RATE EXPERIMENTS. Calculations and corrections Tables 15 50 tabulate data from the marcasite and pyrite oxidation rate experiments. All iron concentration values are divided by the initial concentration of mineral in order to normalize for differences in rate created by variations in mineral concentrations. In studies 1 -4, cuvets were weighed empty, after addition of mineral and incubation medium, after removal of 5 0 mls and addition of hydrochloric acid, and after heating and cooling, in order to calculate mineral concentration and the correction factors. In study 5 the beaker, in which the mineral/seawater suspension was to be treated, was weighed empty and after addition of hydrochloric acid, in order to calculate the dilution factor. With the exception of study 5, all results have two values for the iron concentration (Feah and Febh), and two values for the oxidation rates (Feah/hr and Febh/hr). (The addition of 'be' indicates that the test has been blank corrected by subtraction of the average mineral blank. ) The values designated (ah) have been corrected for

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APPENDIX 5 (Continued) 9 3 addition of acid and for loss of solution due to evaporation, but have not been corrected for removal of 5 mls of solution (which was removed to allow for room for addition of acid and expansion during heating) The (ah) values repre s ent the concentration of iron, if all of the iron formed during the incubation of the mineral is assumed to be in solution The values designated (bh) have been corrected for addition of acid, for loss of solution due to evaporation, and for removal of 5 mls of solution. The (bh) values represent the concentration of iron if essentially all of the iron is not in solution but adsorbed onto available surfaces The assumption is that essentially no iron is removed with the five ml aliquot. From the results of control experiments (Appendix 3), this is most likely and these values have been placed in Tables 3 and 4 The values for iron concentration and oxidation rates in the tables for study 5 are designated Fe and Fe/hr. Evaporative loss of solution was not found to be significant. Since no sample was removed from these tests, only corrections have been made for dilution with acid. Omitted samples All mineral blanks with problems that may affect the concentration of iron determined have been omitted from the calculations in Tables 15 50. Tests with problems that may affect the oxidation rate or the concentration of iron determined ha v e been

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APPENDIX 5 (Continued) left in these tables but not included m the final calculation of the mean listed in Tables 51 60 9 4 Common problems during the experiments which were considered to be an appropriate reason for deletion of data were : loss of solution, loss of mineral sample, suspected loss of mineral sample, contamination of cuvets or boil-over of cuvets during heating Entire experiments in some cases have been omitted One experiment was scrapped entirely due to a delay in processing the mineral blanks thereby, causing elevated blanks During another experiment, the temperature of the cuvet housing of the spectrophotom e ter was not 25C for some of the absorb a nce readings for the iron tests This run was not scrapped since absorbances were not significantly different when remeasured at 25C Another experiment was scrapped because the test samples were assayed with different reagents than the iron standard. Any problems which resulted in omission of the data point from final calculations are indicated in the t a bles. Symbols and abbreviations used in the tables are defi ned in the List of Symbols.

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APPENDIX 5 (Continued) 9 5 Table 15 Marcasite oxidation in 0.7 M NaCI (10-4-86) CUVET T1 T2 T4 T5 T6 b lk T7 blk A593nm 0.0459 0.0521 0.0525 0.118 0.0271 0.1 007 minera l cone 0 .0008122 0 .0007646 0.0007927 0.0018016 0 .0007002 0 .0011963 corr. (df) 1 .0455 1 .0464 1.0465 1 .04 71 1 .0465 1.0478 corr. (cf) 0 .8500 0.8429 0.8409 0.8388 0.8485 0.8433 corr. (hf) 0 .9994 0.9985 0.9976 0.9984 0.9997 0.9978 t ime (hrs) 4 .60 4 .75 7 .93 8.13 Feah 0 .001712 0 .002064 0.002005 0 .001985 0 .001174 0.002552 Febh 0.001392 0 .001663 0.001611 0 .001590 0 .000952 0 .002054 Feah(bc) 0.0005380 0 .0008903 0 .0008307 0 .0008113 Febh(bc) 0.0004401 0.0007109 0.0006591 0 .0006386 Feah/hr(bc) 1 .170E-04 1 .874E-04 1.04 7E04 9.975E-05 Febh/hr(bc) 9.568E-05 1.497E-04 8 .308E-05 7.852E-05 Problems T5 lost T7 problem some mar with ca. 10 % weight

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APPENDIX 5 (Continued) 9 6 Table 16 Marcasite oxidation m 0.7 M NaCI (10-5-86) aJVET R1 blk R2 blk R3 R4 R5 R6 A593nm 0 .0244 0.0463 0 0 0518 0.0969 0 .0905 0 1 052 mineral cone 0 .0007606 0.0008712 0 .0009628 0 .0011232 0 .0010361 corr. (df) 1 .0473 1 .0465 1.0465 1 .0467 1.0453 1 .0453 corr. (cf) 0.8381 0.8630 0.8505 0.8555 0 .8534 corr. (hf) 0.9991 0.9990 0 .9993 0.9993 0.9987 0.9992 time (hrs) 5.56 5.73 5.91 Feah 0.000985 0 .001630 0.003087 0.002467 0.003111 Febh 0.000788 0.001344 0 .002509 0.002019 0.002539 Feah(bc) 0 .001780 0.001160 0 .001804 Febh(bc) 0 .001443 0.000953 0.001474 Feah/hr(bc) 0.000320 0 .000203 0.000305 Febh/hr(bc) 0.000260 0 .000167 0.000249 Problems R3 no wt. Table 17 Marcasite oxidation in 0.7 M NaCI (10-8-86) aJVET T1 blk T2 blk T4 T5 T6 T7 A593nm 0.0171 0 .0156 0 .0887 0.1252 0.0712 0.1853 mine ra l cone 0.0008728 0 .0007399 0 .0009373 0.0008855 0 .0006518 0.0011267 corr. (df) 1.0592 1 .0563 1 0571 1.0592 1 .0583 1.0581 corr. (cf) 0.8164 0 .8243 0 .8213 0.8009 0 801 7 0 .8022 corr. ( hf) 0.9991 0 .9980 0 .9973 0.9990 0.9993 0.9903 time (hrs) 5.62 5.83 6.00 6.18 Feah 0.0006175 0.000662 0 0.0029715 0 .0044557 0.0034411 0.0051323 Febh 0.0004759 0.0005166 0 0023086 0 .0033694 0.0026068 0.0038912 Feah(bc) 0 .002332 0 .003816 0 .002801 0 .004493 Febh(bc) 0 .001812 0.002873 0 .002111 0 .003395 Feah/hr(bc) 0.0004152 0.0006542 0.0004669 0 .0007266 Febh/hr(bc) 0 .0003227 0.0004925 0.0003518 0.0005490 Problems T7 leaked heating

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APPENDIX 5 (Continued) 9 7 Table 18 Marcasite oxidation m 0.7 M NaCI (10-10-86) aJVET R1 blk R2 blk R3 R4 R5 R6 A593nm 0.0643 0.0414 0 .2159 0 1041 0.1202 0.1298 mineral cone 0 .0006784 0 .0006739 0 .0006418 0.0007158 0.0005782 0 .0006265 corr. (df) 1.0478 1 .0456 1 .04 70 1 .0467 1 .0461 1 .0462 corr. (cf) 0.8455 0 .8513 0 .84 70 0.8483 0.8496 0 .8501 corr. (hf) 0.9989 0.9993 0.9992 0 .9990 0.9960 0.9993 time (hrs) 6 .80 6.98 7 .17 7.47 Feah 0 .002890 0.001870 0.010253 0.004430 0.006309 0.006309 Febh 0 .002332 0 .001522 0.008294 0.003590 0.005124 0 .005126 Feah(bc) 0.007873 0.002050 0.003930 0.003929 Febh(bc) 0 .006367 0.001663 0.003197 0 .003199 Feah/hr(bc) 0.0011578 0 .0002936 0 .0005483 0.0005262 Febh/hr(bc) 0.0009363 0.0002382 0 .0004461 0 .0004285 Problems R3 may be R4 spilt contam during -inated heating Table 19 Marcasite oxidation in seawater (10-31-86) aJVET T1 BLK T2 BLK T4 T5 T6 T7 A593nm 0.0587 0 .0616 0 .0525 0.0374 0 .1717 0 .0514 mineral cone 0.0006868 0.0006401 0.0005576 0 .0004257 0.0006706 0 .0005028 corr. (df) 1.0453 1 .0455 1.0455 1.0462 1.0459 1.0465 corr. (cf) 0.8538 0.8530 0 .8553 0 .8512 0.8513 0.8464 corr. (hf) 0.9977 0 .9972 0.9982 0 .9993 0 .9988 0.9962 time (hrs) 8.01 8 .14 8.31 8 .56 Feah 0.002664 0.002999 0.002937 0 .002745 0.007994 0.003185 Febh 0.002176 0 .002447 0.002403 0.002234 0 .006507 0.002576 Feah(bc) 1 .056E-04 -8.623E-05 5.163E-03 3 .537E-04 Febh(bc) 9 .122E05 -7.773E-05 4 .195E03 2 .649E-04 Feah/hr(bc) 1 .318E05 -1.059E-05 6 .214E-04 4.133E-05 Febh/hr(bc) 1. 139E-05 -9.54 7E-06 5.050E-04 3 .095E-05 Problems

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APPENDIX 5 (Continued) 9 8 Table 20 Marcasite oxidation in seawater (11-3-86) CUVET R1 R2 R3 R4 BLK R5 BLK R6 A593nm 0 .0445 0.2662 0.1357 0 .0484 0 1141 0 .1557 mineral cone 0.0003047 0.0008192 0 .0005182 0 .0004106 0 .0005424 0.0004834 corr. (df) 1 .0468 1 .0449 1.0464 1 .0459 1 .0455 1 .0455 corr. (cf) 0.8488 0.8536 0 .8505 0.8525 0.8534 0.8505 corr. (hf) 0.9994 0.9969 0.9993 0 .9985 0.9984 0 .9989 time (hrs) 7 .83 7.93 8.17 8 .35 Feah 0 .004643 0.010286 0 .008321 0 .003740 0.006673 0 .010221 Febh 0 .003765 0.008403 0 .006763 0 .003049 0.005447 0 .008315 Feah(bc) -5.638E-04 5.079E-03 3 .114E-03 4 .987E-03 Febh(bc) 4 .829E-04 4.155E-03 2 .515E-03 4 .053E-03 Feah/hr(bc) -7.197E-05 6.409E04 3.814E-04 5 .972E-04 Febh/hr(bc) -6.1 65E-05 5 .243E-04 3.080E-04 4 .854E-04 Problems R1 problem with weight Table 21 Marcasite oxidation in seawater (11-4-86) CUVET T1 T2 T4 T5 T6 BLK T7 BLK A593nm 0 1 049 0.0621 0 .0416 0 .0955 0 .0234 0.0599 mineral cone 0 .000696 0 .0003317 0 .0003416 0 .0005126 0 .0004335 0.0005074 corr. (df) 1 .0455 1.0452 1.0459 1.0465 1.0455 1.0457 corr. (cf) 0.8510 0.8509 0.8485 0 .8481 0 .8554 0.8545 corr. (hf) 0 .9963 0.9979 0 .9980 0.9993 0.9995 0 .9978 time (hrs) 8.43 8.55 8. 71 8 .83 Feah 0 .004654 0.005791 0.003769 0 .005777 0 .001672 0.003652 Febh 0 .003788 0.004714 0.003058 0.004682 0 .001368 0.002985 Feah(bc) 1 .992E-03 3 .128E-03 1 1 07E-03 3 .115E-03 Febh(bc) 1 .612E-03 2 .538E-03 8.815E-04 2 .506E-03 Feah/hr(bc) 2 .365E-04 3.659E-04 1.271 E-04 3 .530E-04 Febh/hr(bc) 1.914E-04 2 .968E-04 1.012E-04 2.839E-04 Problems

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APPENDIX 5 (Continued) 9 9 Table 22 Marcasite oxidation m seawater (11-13-86) CUVET R1 BLK R3 R4 R6 T2 T4 A593nm 0 .0123 0 .0713 0 .0576 0 .0933 0 0351 0 .0377 m i neral cone 0.0003753 0.0004322 0 .0003808 0.0003436 0.0002629 0 .000291 0 corr. (df} 1 .0454 1.0456 1 .0455 1.0452 1.0445 1 .0454 corr. (cf) 0.8654 0 .8640 0.8651 0.8670 0.8687 0 .8642 corr. (hf) 0 .9989 0 .9993 0 .9996 0 .9934 0.9989 0.9990 time (hrs) 16.29 16.47 16.65 16.79 16.95 Feah 0.001093 0 .005509 0.005051 0 .009008 0.004450 0 .004323 Febh 0 .000905 0 .004552 0.004180 0 .007472 0.003701 0 .003574 Feah(bc) 4.415E-03 3 .958E-03 7.915E-03 3 .357E-03 3 .229E-03 Febh ( bc) 3 .646E-03 3 .275E-03 6.567E-03 2 796E-03 2.669E-03 Feah/hr(bc) 2.710E-04 2.404E-04 4 754E-04 1.999E-04 1 .905E-04 Febh/hr(bc) 2 .238E-04 1 .989E-04 3 .944E-04 1.665E-04 1 .574E-04 Problems R 6 b oile d over Table 23 Marcasite oxidation in 7% Oz (12-9-86) CUVET T2 T4 BLK T5 T7 T8 T9 A593nm 0.1124 0.1576 0 .1146 0.2522 0.2239 0.1577 minera l cone 0.0005863 0 .0006136 0 .0006780 0.001 025 0.001207 0.000947 corr. (df) 1.0446 1.045 0 1.0458 1 0452 1.0458 1 .0449 corr. (cf) 0 .8658 0.8636 0 .8636 0.8658 0.8473 0 .8662 corr. (hf) 0.9983 0 .9299 0 .9890 0.9986 0.9982 0.9987 time (hrs) 19.85 20.22 20.62 24.55 20.30 Feah 0.006500 0 .008115 0.005685 0.008348 0.006294 0 .005652 Febh 0.005387 0 .006706 0.004694 0.006914 0.005099 0.004685 Fe ah(bc) -1.522E-03 -2.338E-03 3.255E-04 -1. 728E-03 -2.370E-03 Febh(bc) -1.253E-03 1 .946E-03 2. 744E-04 -1.540E-03 -1.955E-03 Feah/hr(bc) -7.667E-05 -1.156E-04 1.579E-05 -7.040E-05 -1.168E-04 Febh/hr(bc) 6 .31 OE-05 -9.625E-05 1 331 E-05 -6.275E-05 -9.629E-05 Problems T4 may be T5 b o iled T 7 mar on T8 s pilt Delay for Run contam over both caps so lut io n mineral scrapped -inate prior blanks to hea ti ng.

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APPENDIX 5 (Continued) 100 Table 23 continued CUVET R1 R3 R4 R7 R8 BLK R9 A593nm 0 1401 0 .18 0.2221 0 .2992 0.2719 0.1272 m i neral cone 0 .000861 0 .000791 0 .000636 0 .00137 0 .001164 0.000669 corr. (df) 1 .0457 1.0459 1 0451 1.0453 1 .0448 1.0452 corr. (cf) 0 .8629 0 .8640 0 .8655 0 .864 7 0 .8661 0 .8663 corr. (hf) 0 .9988 0.9984 0.9906 0 .9987 0 .9993 0 .9997 time (hrs) 23.78 23.55 23.16 23.95 23.32 Feah 0 .005525 0 .007726 0 .011754 0 .007413 0.007930 0 .006456 Febh 0.004559 0 .006382 0 .009734 0 .006132 0.006574 0 .005350 Feah(bc) -0.002497 -2.961 E-04 3 .7314E-03 -6.094E-04 -1.567E-03 Febh(bc) -0.002081 -2.574E-04 3.0941 E-03 -5.079E-04 -1.289E-03 Feah /hr(bc) -1.050E-04 -1.258E-05 1.6113E-04 -2.545E-05 -6. 719E-05 Febh /hr(bc) -8. 748E-05 -1.093E-05 1 .336E-04 -2. 121 E -05 -5.530E-05 Problems R4 leaked R8 heated Temperature Run during fo r 5 min problem scrapped heat i ng extra Table 24 Marcasite oxidation in 7% 02 (12-13-86) CUVET R1 R3 R4 BLK AS BLK R7 R8 BLK R9 A593nm 0 .0816 0 .0772 0 .0803 0 .0415 0.2044 0 .0670 0 1721 mineral cone 0 .000891 0 .000591 0.000941 0 .000818 0 .001342 0 .001434 0 .001159 corr. (df) 1 .0456 1.0461 1 .0453 1 .0449 1 .0454 1 .0449 1 .0453 corr. (cf) 0 .8646 0 .8635 0.8665 0.8666 0 .8642 0 .8648 0 .8653 corr. (hf) 0 .9987 0 .9530 0.9616 0 9991 0.9989 0.9995 0.9994 time (hrs) 20.82 20.45 21.14 25.15 Feah 0.003082 0 .004196 0.002766 0 .001708 0.005126 0 .001572 0 .005000 Febh 0.002548 0 .003464 0.002293 0.001416 0 .004238 0 .001301 0 .004139 Feah(bc) 0 .001442 0 .002556 0 .003486 0 .003360 Febh(bc) 0.001189 0 .002105 0 .002879 0.002780 Feah/hr(bc) 6 .924E05 1 .250E-04 1.649E-04 1.336E-04 Febh/ h r(bc) 5.713E-05 1.029E-04 1.362E-04 1 1 06E-04 Problems R3 leaked R4b lk cap heating blew off

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APPENDIX 5 (Continued) 101 Table 24 continued CUVET T2 T4 T5 BLK T7 T8 T9 A593nm 0.1666 0 1 017 0 .0585 0 .1176 0.2074 0 .2073 mineral cone 0.000929 0.000746 0 000901 0 .000798 0.001054 0 .000994 corr. (df) 1 .0446 1.0450 1.0453 1.0450 1.0448 1 0451 corr. (cf) 0 .8672 0.8664 0 .8660 0.8666 0 .8646 0.8656 corr. (hf) 0.9975 0 .9987 0.9218 0.9966 0 .9993 0 .9992 time (hrs) 20.89 20.50 24 62 24. 90 24.76 Feah 0.006024 0 .004588 0 .002017 0 .004946 0 .006621 0 .007023 Febh 0 .005001 0 .003804 0 001671 0.004102 0.005479 0.005817 Feah(bc) 0 .004384 0.002948 0 .003306 0 .004981 0 .005383 Febh(bc) 0 .003642 0 .002445 0.002743 0 .004120 0 .004458 Feah/hr(bc) 2 .099E04 1 .438E-04 1 .343E-04 2 .000E-04 2 .174E-04 Febh/hr(bc) 1 .744E-04 1 .193E-04 1 .114E-04 1 .655E-04 1 .800E-04 Problems T5 blk boiled over Table 25 Marcasite oxidation in 7% Oz (12-17-86) CUVET T2 BLK T4 BLK T5 T7 T8 T9 A593nm 0 .0120 0 0281 0.1096 0.0656 0.1841 0.1254 mineral cone 0.000802 0 .000883 0.001099 0 .000730 0 .000737 0.000743 corr (df) 1 .0443 1.0452 1.0455 1.0454 1.0446 1.0453 corr.(cf) 0 .8673 0 .8636 0 .8649 0.8658 0.8660 0.8643 corr (hf) 0.9980 0.9991 0.9994 0.9989 0 .9995 0.9979 t i me (hrs) 26. 25 25.84 22.30 22.13 Feah 0 .000502 0.001071 0.003358 0.003023 0 .008410 0.005676 Febh 0.000417 0 .000885 0.002778 0.002504 0 .006972 0 .004693 Feah(bc) 0.001712 0.001377 0.006764 0.004030 Febh(bc) 0 .001414 0.001140 0.005608 0 .003329 Feah/hr(bc) 6.524E-05 5 .330E-05 3 .033E-04 1 821 E-04 Febh/hr(bc) 5 .387E-05 4.411 E-05 2.515E-04 1 .505E-04 Problems

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APPENDIX 5 (Continued) 102 Table 25 continued CUVET R1 R3 R4 R5 BLK R7 R9 A593nm 0.1 046 0.0756 0.1351 0.1180 0 .1238 0 .1824 mineral cone 0 .000775 0 .000706 0 001 048 0 .001179 0 .000742 0 .001395 corr. (df) 1.0453 1.0457 1 .0453 1.0447 1 .0461 1 .0455 corr. (cf) 0 .8649 0 .8619 0 .8654 0 .8662 0 .8613 0 .8651 corr. (hf) 0.9993 0.9990 0 9991 0 .9982 0 .9986 0 .9999 time (hrs) 25.96 25.57 22.36 21.86 22.69 Feah 0 .004546 0 .003605 0 .004339 0 .003364 0 .005619 0 .004405 Febh 0 .003761 0 .002971 0 .003592 0 .002789 0 .004627 0 .003645 Feah(bc) 0 .002900 0 .001959 0 .002693 0.003974 0 .002759 Febh(bc) 0 .002397 0 .001607 0 .002228 0.003263 0.002281 Feah /hr(bc) 1 .117E-04 7.662E-05 1.205E-04 1.818E-04 1.216E-04 Febh /hr(bc) 9 .235E-05 6.286E-05 9 .967E-05 1.493E-04 1 .005E-04 Problems Table 26 8 6) Marcasite oxidation at low temperature (12-22-CUVET R1 blk R3 R4 R5 R7 R9 A593nm 0.0155 0 .0329 0 .0270 0.0281 0 .0529 0.0206 mineral cone 0 .000651 0.000624 0 .000574 0.000858 0 .001193 0 .000709 corr. (df) 1 .0456 1 .0457 1 .0453 1.0450 1 .0455 1 .0454 corr. (cf) 0 8641 0 .8618 0 .8669 0.8651 0 .8630 0 .8643 corr. (hf) 0.9990 0 .9978 0 .9989 0.9986 0.9987 0 .9992 time (hrs) 21.88 21 .42 22.71 23.69 22.27 Feah 8 .074E-04 1 786E-03 1.593E-03 1 1 09E-03 1 .503E-03 9.848E-04 Febh 6 .672E-04 1 .472E-03 1 321 E-03 9 .183E-04 1.240E-03 8 .142E-04 Feah(bc) 2.357E-04 4 .262 E -05 -4.413E-04 4 792E-05 -5.657E-04 Febh(bc) 1 .774E-04 2 .653E-05 -3.764E-04 -5.439E-05 4 .805E-04 Feah/hr(bc) 1 .078E-05 1 .990E-06 -1.943E-05 2 .023E-06 2 .540E-05 Febh/hr(bc) 8 1 08E-06 1 .239E-06 -1.657E-05 -2 .296E-06 -2.158E-05 Problems

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APPENDIX 5 (Continued) 103 Table 26 continued CUVET T2 blk T4 T5 T7 blk T8 T9 A593nm 0.0522 0 .0506 0.0289 0.0469 0.0830 0.0762 mineral cone 0 .001107 0.001034 0 .000691 0 .000706 0.000577 0.001504 carr. (df) 1 .0446 1 .0452 1.0456 1.0444 1 .0450 1 .0450 carr. (cf) 0 .8644 0.8662 0.8644 0.8810 0.8642 0.8657 carr. (hf) 0.9974 0 .9932 0 .9990 0.9987 0.9992 0.9982 time (hrs) 23.12 21.96 21.55 23.82 Feah 1.595E-03 1 .648E-03 1.417E-03 2.249E-03 4.870E-03 1 .715E-03 Febh 1.319E-03 1 .366E-03 1.171E-03 1.897E-03 4 .028E-03 1.421E-03 Feah(bc) 9 .782E-05 1 .335E-04 3.319E03 1.646E-04 Febh(bc) 7 .119E-05 -1.233E-04 2.733E-03 1.262E-04 Feah/hr(bc) 4 231 E-06 -6.080E-06 1.540E-04 6 911 E-06 Febh/hr(bc) 3.079E-06 -5.617E-06 1.268E-04 5 .299E-06 Problems T4 boiled over Table 27 Marcasite oxidation at low temperature (1-3-87) CUVET T2 BLK T4 T5 T7 BLK T8 T9 A593nm 0.0207 0.0379 0.0186 0 .0330 0.0306 0.0326 mineral cone 0 .000656 0 .000830 0.000528 0 .000552 0.000412 0.000585 carr. (df} 1.0447 1 .0453 1.0454 1 .0453 1.0446 1 .0448 carr. (cf) 0.8685 0.8608 0 .8638 0.8645 0.8658 0.8654 carr. (hf) 0.9654 0 .9979 0 .9493 0 .9960 0.9992 0.9981 time (hrs) 67.74 41.46 41.26 41.57 Feah 1 .032E-03 1 .545E-03 1.134E-03 2 021 E-03 2 .515E-03 1.887E-03 Febh 8.580E-04 1 .272E-03 9.368E-04 1 671 E-03 2 .085E03 1 .563E-03 Feah(bc} 3 .570E-05 -3. 752E-04 1.006E-03 3 781 E-04 Febh(bc) 2 .200E-05 -3.132E-04 8.346E-04 3 .130E-04 Feah/h r(bc} 5 .270E-07 -9.050E-06 2.439E-05 9.094E-06 Febh/hr(bc} 3 .248E-07 -7.554E-06 2 .023E-05 7 .529E-06 Problems T4 lost T5 spilt T8 lost sample solution sample

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APPENDIX 5 (Continued) 104 Table 27 continued aJVET A1 A3 A4 AS A7 BLK A9 AS93nm 0 .0466 0 .0173 0 .0466 0 .0640 0 .0219 0.0786 mineral cone 0 .00086S 0 .000391 0 .000679 0 .000610 O .OOOS03 0.000806 corr. (df) 1 .0460 1.0469 1.04S4 1.0449 1.04S2 1 .04S3 corr. (cf) 0 .8S22 0.8404 0 8631 0 .86S4 0 86S6 0 .8642 corr. (hf) 0.9992 0 .9988 0 .9994 0 .9993 0 .9991 0.9994 time (hrs) 67.66 41.06 67.21 41.73 67.37 Feah 1.827E-03 1 .S01 E-03 2 .327E-03 3 SSSE-03 1.474E-03 3.307E-03 Febh 1 .489E-03 1 .20SE-03 1.921 E-03 2 .944E-03 1 221 E-03 2 .734E-03 Feah ( bc) 3.18SE-04 -7.873E-06 8 .176E-04 2 .046E-0 3 1 .798E-03 Febh ( bc) 2.390E-04 -4 .493E-OS 6 71 OE-04 1.694E-0 3 1 .484E-03 Feah /hr(bc) 4.707E-06 -1.918E-07 1 .217E-os 4.903E-OS 2 668E-OS Febh /hr(bc) 3.S32E-06 -1.094E-06 9 .98SE-06 4 060E-OS 2 202E-OS Problems A4 contam -in ant Table 28 Marcasite oxidation at low temperature (1-31-87) CUVET A3 BLK A4 AS A7 A9 T2 AS93nm 0 .027S 0.0472 0 .1883 0.2109 0.1722 0 .1338 m i neral cone 0 .001312 0 .001240 0 .001323 0 .002661 0 .001820 0 .001S48 corr. (df) 1.04S8 1 .04S4 1.04SO 1.04SS 1 04S3 1.0449 corr. (cf) 0.8603 0.86S2 0.8644 0.86S1 0 .8666 0.8631 corr. (hf) 0 .9988 0.9993 0 .9987 0.9991 0 .9992 0 .9976 time (hrs) S3 .96 S4.28 SS.63 SS.32 S4 .98 Feah 7 .S66E-04 1 .374E-03 S .134E-03 2.861 E-03 3 .41SE-03 3 .114E-03 Febh 6.224E-04 1.137E-03 4 .246E-03 2.367E-03 2 .831E-03 2 S72E-03 Feah(bc) 1 .927E-04 3 9S2E -03 1.679E-03 2.234E-03 1.933E-03 Febh(bc) 1.619E-04 3.271 E-03 1.392E-03 1 .8S6E-03 1 .S97E-03 Feah /hr(bc) 3.S71 E-06 7 281 E -os 3 019E-OS 4 038E-OS 3.S1SE-OS Febh / h r(bc) 3 001 E-06 6.02SE-OS 2 S02E -OS 3 3SSE-05 2.905E-05 Problems A4 weight problem

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APPENDIX 5 (Continued) 105 Table 28 continued CUVET T4 T5 T7 BIK A593nm 0 .1301 0 .0919 0 0741 mineral cone 0.001424 0 001 079 0 .001570 carr (df) 1.0451 1 .0457 1 .0453 carr. (cf) 0.8653 0 .8636 0 .8644 carr. (hf) 0.9982 0.9993 0 .9427 time (h r s) 54.58 53.54 Feah 3 .293E-03 3 .075E-03 1 .607E-03 Febh 2 .727E-03 2 .540E-03 1 .329E-03 Feah(bc) 2 .112E-03 1.894E-03 Febh(bc) 1 .751E-03 1 .564E-03 Feah/h r(bc ) 3 .870E-05 3 .537E-05 Febh/hr(bc) 3 .209E-05 2.922E-05 Problems Table 29 Marcasite oxidation at high pressure (3-7-87) Type min b l k min blk m i n blk SWbl k SWbl k test test Tube 3 (1) 6 (2 ) 9 (3) 13 (4) 15 (5) 1 (6) 10 (7) A593nm 0 .0450 0 .0280 0 .0285 0 .0192 0 0201 0 0811 0 .0292 A593nm sbc 0.0254 0.0084 0.0089 0 .0613 0 .0094 mine r al cone 0 .010347 0 .003538 0 .002995 0 0 0.014019 0 .002165 carr. (df) 14.4119 16.3661 14 0801 14.3478 14.4165 16.9016 17.8398 time (hrs) 44.95 45.05 Rl 0 .001197 0.001309 0 001411 0 .002503 0.002612 Fe(bc) 0 .001198 0 .001306 Fe/hr(bc) 2 .66E-05 2 .9E-05 P roblems

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APPENDIX 5 (Continued) 106 Table 29 continued Type test sw blk SWbl k test SWblk SWblk Tube 11 (8) 14 (9) 17 (10) 5 ( 11) 16 (13) 18 (14) A593nm 0.0246 0.0192 0 .0187 0.0292 0 .0218 0 .0197 A593nm sbc 0.0048 0 .0094 mineral cone 0 .001554 0 0 0.003395 0 0 corr. (df) 18.3432 20.6178 20.8993 20.9039 21.8650 18.6316 time (hrs) 45.06 45. 1 0 45.13 46.06 46.18 46.22 Fe 0 .0019 0 .001952 Fe(bc) 0 .000594 0 .000646 Fe/hr(bc) 1 .32E-05 1.4E-05 Problems Table 30 Marcasite oxidation at high pressure (3-14-87) Type SWblk SWblk min blk min blk min blk Tube 19 (1) 15 (2) 11 (3) 8 (4) 1 (5) A593nm 0.0118 0.0140 0 .0202 0.0182 0 .0200 A593nm sbc 0 .0073 0.0053 0 0071 mineral cone 0 0 0 .0047302 0.0034714 0.0057792 corr. (df) 18.2334 17.4668 17 .6842 19.1442 17.2746 time (hrs) Fe 0 .0009226 0 .0009881 0 .0007174 Fe(bc) Fe/hr(bc) problems

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APPENDIX 5 (Continued) 107 Table 30 continued Type SWblk test test test test Tube 18 (6) 13 (7) 6 (8) 3 (9) 2 (1 0) A593nm 0 .0159 0.0386 0 .0312 0 0421 0.0352 A593nm sbc 0.0233 0 .0159 0 .0268 0 .0199 mineral cone 0 0 .004549 0 .0043583 0 .0036621 0 .0036049 corr. (df) 13 .2998 15.3318 18 .7620 12. 8741 15 .0320 time (hrs) 92.85 92. 8 92.716667 92.666667 92.658333 Fe 0 .0026546 0 .0023138 0.0031849 0 .0028051 Fe( be) 0 .0017786 0 .0014378 0.0023089 0 .0019291 Fe/hr(bc) 1 .917E-05 1.551E-05 2.492E-05 2 .082E-05 problems Table 30 continued Type SWblk test test test test Tube 16 (12) 12 (13) 9 (14) 5 (15) 4 (16) A593nm 0 .0147 0 0501 0.0419 0 .0457 0 0321 A593nm sbc 0.0348 0 .0266 0.0304 0 .0168 mineral cone 0 0 .0044346 0.004282 0.0045871 0 .0030804 corr. (df) 12.9314 13.0892 13.6705 13.3776 13.1167 time (hrs) 94.258333 94.216667 94.183333 94.133333 94.116667 Fe 0 .0034723 0 .0028707 0.0029969 0 .0024183 Fe( be) 0 .0025962 0.0019947 0.0021209 0 .0015422 Fe/hr(bc) 2. 756E-05 2 .118E-05 2.253E-05 1.639E-05 Probl e m s

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APPENDIX 5 (Continued) 108 Table 31 Marcasite oxidation at high pressure (3-21-87) Type SWblk min blk min blk min blk SWblk SWblk Tube 18 (1) 11 (2) 5 (3) 1 (4) 17 (5) 16 (6) A593nm 0 .0153 0 .0258 0 .0237 0 .0227 0 .0156 0 .0189 A593nm sbc 0 .0104 0 .0083 0.0073 mineral cone 0 .000000 0.003185 0.004225 0 .003872 0 .000000 0.000000 corr (df) 14.4600 12.8192 15.0984 14.4691 12.5263 12.3982 time (hrs) 93.85 Fe 1.32E-03 9 .37E-04 8 .61E-04 Fe( be) Fe/hr(bc) Problems Table 31 continued Type test test test test test test Tube 12 (7) 10 (8) 8 (9) 7 (1 0) 6 (11) 2 (12) A593nm 0.0490 0 .0386 0.0303 0.0285 0 .0497 0.0295 A593nm sbc 0.0307 0 .0203 0.0120 0 .0102 0 .0314 0 .0112 mineral cone 0.003605 0 .003338 0.002232 0 .002394 0 .005341 0.002289 corr (df) 13.4027 13.7071 13.4668 13.6636 11.2883 13.8055 time (hrs) 93.79 93.77 93.76 93.75 93.74 93.70 Fe 3 .62E-03 2 .64E-03 2.29E-03 1 .84E-03 2.11 E-03 2 .14E-03 Fe(bc) 2 .58E-03 1 .60E-03 1.25E-03 8.01 E-04 1.07E-03 1.10E-03 Fe/hr(bc) 2 .75E-05 1. 71 E-05 1.33E-05 8.54E-06 1.14E-05 1.17E-05 Problems 12(7) leaked

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APPENDIX 5 (Continued) 109 Table 31 continued Type SWblk SWblk test test test SWblk Tube 15 (13) 13 (14) 9 (15 ) 4 (16 ) 3 (17) 14 (18) A593nm 0 .0190 0 .0182 0 .0439 0.0326 0.0374 0.0173 A593nm sbc 0 .0256 0 0143 0.0191 mineral cone 0.000000 0 .000000 0.004158 0.002537 0 .003624 0.000000 corr. (df) 13.6979 14.5812 14.3753 13.6384 14.7460 16.1213 time (hrs) 94 .90 94.86 94.84 Fe 2.81 E -03 2.44E-03 2.46E-03 Fe( be) 1. 77E-03 1.39E-03 1.42E-03 Fe/hr(bc) 1 .86E-05 1 .4 7E-05 1 .50E-05 Problems Table 32 Marcasite oxidation at high pressure (3-26-87) Type SWblk min blk min blk min blk SWblk SWblk Tube 13 (1 ) 9 (2) 6 (3) 2 (4) 14 (5 ) 1 2 (6) A593nm 0 .0208 0 0 241 0 0251 0 .0239 0.0205 0.0372 A593nm sbc 0 .0035 0 .0045 0.0033 mineral cone 0 .000000 0.002880 0 .003624 0.002775 0 .000000 0.000000 corr. (df) 19 .8078 20.3181 19.5034 15.4851 1 3 .5103 12.8055 t ime (hrs) Fe 8.23E-04 8 .10E-04 6.13E-04 Fe(bc) Fe/hr(bc) Problems

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APPENDIX 5 (Continued) 110 Table 32 continued Type test test test SWblk SWblk SWblk Tube 10 (7) 5 (8) 3 (9) 19 (1 0) 15 (11) 11 (12) (beaker) A593nm 0 .0498 0.0493 0 .0472 0.0375 0 0391 0 .0380 A593nm sbc 0.0119 0.0114 0 .0093 mineral cone 0.003185 0 .002689 0.002842 0 .000000 0 .000000 0 .000000 corr. (df) 14 .2540 12.9085 14.0458 19.9542 17.8467 14.8696 time (hrs) 138.32 138.24 138.20 Fe 1.80E-03 1 .85E-03 1 .56E-03 Fe(bc) 1.05E-03 1.1 OE-03 8.09E-04 Fe/hr(bc) 7.63E-06 7 .99E-06 5 .85E-06 Problems Table 32 continued Type test test test SWblk Tube 8 (13) 4 (14) 1 (15) 17 (16) A593nm 0 .0413 0.0508 0 .0426 0.0376 A593nm sbc 0 .0034 0 .0129 0 .0047 mineral cone 0.001469 0 .003786 0 .001116 0.000000 corr. (df) 14.9542 15.9565 12.9062 13.1510 time (hrs) 139.40 139.34 139.30 Fe 1.18E-03 1 .84E-03 1 .85E-03 Fe(bc) 4.29E-04 1 .09E-03 1.10E-03 Fe/hr(bc) 3.08E-06 7.84E-06 7 .88E-06 Problems 4(14) lost solution

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APPENDIX 5 (Continue d ) 1 1 1 Table 33 Pyrite oxidation in 0.7 M N a C I (10-13-86) aJVET T1 BL K T 2 BL K T4 T 5 T 6 T7 A 593nm 0 1907 0 .1048 0 1 917 0.2265 0.4642 0 .4268 mineral c on e 0. 001451 0.001159 0 001297 0 001365 0.001980 0 .001152 corr. (df) 1 .046 1 1 0 461 1.0467 1. 0469 1.0463 1.0466 corr. (cf) 0 8472 0.84 6 4 0.845 4 0.8436 0.8452 0.8447 corr. ( hf) 0 .9992 0.9985 0 9 991 0 .99 93 0.999 5 0.998 8 ti me ( hr s ) 7.03 7. 1 6 7. 3 9 7.58 Feah 4 076E 03 2 .804E-03 4 5 8 8E -03 5.153 E 0 3 7.276E-03 1.149E-02 Febh 3 301 E-03 2.269E -03 3. 706E 0 3 4 152E-03 5.878E0 3 9.277E-03 F ea h ( bc ) 1.1 4 8E-03 1.713E-03 3.836E-03 8.053E-03 F ebh(bc) 9 .21 O E0 4 1.367E-03 3.093E-03 6.492E-03 Feah/h r( b c) 1.634E-04 2 .393E-04 5. 190E-04 1.063 E-03 Febh /hr( b c) 1 .311 E 0 4 1.910E-04 4. 184E-04 8.570E-04 Pr o blems Table 34 Pyrite o xidation in 0.7 M NaCI (10-14-86) aJVET R1 BL K R 2 R 3 R 4 BL K R 5 R6 A593nm 0.031 0 0.1 034 0.0740 0. 0875 0.1217 0 .2864 m in era l c o n e 0. 0 0 0 701 0.00120 0 0.000689 0.002215 0.001775 0.002349 cor r ( d f) 1.0464 1.0452 1.0464 1.0462 1.0457 1.0458 co rr. (cf) 0 8 4 9 4 0 .8553 0.8499 0.8507 0.8520 0.8518 co rr (h f ) 0 9 9 8 5 0.9992 0 9 9 9 8 0 .9989 0.9986 0.9994 ti m e (h r s) 7.41 7.63 7.78 7.96 Feah 1 441 E 03 2. 806E-0 3 3 .507E-03 1 .288E-03 2.233E-03 3.975E-03 Febh 1 .169E 03 2.296E-03 2 .848E-03 1 .047E 0 3 1.819E-0 3 3.238E-03 F ea h ( bc ) 1.442E-03 2. 142E-0 3 8.685E-04 2.61 1 E-03 Febh ( bc ) 1 188E-03 1.740E-0 3 7. 107E-04 2. 130E-03 Feah /hr( bc) 1.947E-0 4 2 .81 OE-0 4 1.117E-04 3 .281E-04 Febh/hr( bc) 1.604E-04 2.282E-0 4 9 141E-05 2.676E-04 Prob le m s

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APPENDIX 5 (Continued) 112 Table 35 Pyrite oxidation in 0.7 M NaCI (10-16-86) CUVET T1 BLK T2 BLK T4 T5 T6 T7 A593nm 0 .0368 0.0329 0 .1200 0 .0614 0 0551 0 .0587 m i neral cone 0 .000847 0.001698 0 .001845 0 .001233 0 .001086 0 .001293 corr. (df) 1 .0455 1 .0459 1 .0460 1.0470 1 .0456 1 .0463 corr. (cf) 0.8517 0 .8503 0.8508 0 8481 0 851 7 0 .8498 co r r (hf) 0 .9986 0 .9986 0.9986 0 .9995 0 .9998 0 .9985 time (hrs) 7.07 7.23 7.40 7 .53 Feah 1 .361E-03 6 .073E-04 2 .039E-03 1 .564E-03 1 .592E-03 1.423E-03 Febh 1 1 08E-03 4 .937E-04 1.658E-03 1 .267E-03 1.297E-03 1 .156E-03 Feah(bc) 1.055E-03 5 796E-04 6.079E-04 4 .394E-04 Febh(bc ) 8 .572E-04 4 .655E04 4.956E-04 3 .550E-04 Feah/hr(bc) 1.492E-04 8 .013E-05 8.215E-05 5 .833E-05 Febh /hr(bc) 1 .213E-04 6 .436E-05 6.697E-05 4. 713E-05 Problems T7 sample lost Table 36 Pyrite oxidation in 0.7 M NaCI (10-17-86) CUVET R1 R2 R3 R4 R5BLK R6BLK A593nm 0 1181 0 .0585 0 .0378 0 .0292 0 .0396 0.0318 mineral cone 0 .001161 0.001022 0 .001042 0 .000854 0.000794 0 .000964 corr. (df) 1 .0466 1 .0454 1.0465 1 .0457 1 .04 75 1 .0468 corr. (cf) 0 .8492 0.8526 0 .8497 0.8524 0.8505 0.8460 corr. (hf) 0 .9989 0 .9989 0 .9985 0 .9993 0 .9982 0 .9995 time (hrs) 7.91 7 .71 7.48 7 .26 Feah 3 .152E-03 1. 772E-03 1 .124E-03 1.059E-03 1 .547E-03 1.023E-03 Febh 2 .558E-03 1.445E03 9.128E-04 8 .635E-04 1 .256E-03 8 271 E-04 Feah ( bc) 1 .867E-03 4.871 E-04 -1.610E-04 -2.258E-04 Febh(bc) 1 .516E-03 4 .038E-04 -1.288E-04 -1.780E-04 Feah/hr(bc) 2 .361 E -04 6.319E-05 -2.153E-05 3 .11 OE-05 Febh/hr(bc) 1 .917E-04 5.238E-05 -1. 723E-05 -2.453E-05 Problems

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APPENDIX 5 (Continued) 113 Table 37 Pyrite oxidation in seawater (10-28-86) CUVET T1 BLK T2 T4 T5 T6 BLK T7 A593nm 0 .0311 0 .0792 0 .0587 0 .0408 0.0372 0.1197 mineral cone 0 .000596 0 .000596 0 .000596 0 .000596 0 .000596 0 .000596 corr. {df) 1.0469 1.0456 1 .0462 1 .0465 1.0465 1 .0460 corr. {cf) 0.8515 0.8496 0 .8480 0.8478 0.8483 0.8479 corr. {hf) 0 .9990 0 .9988 0.9992 0.9996 0.9989 0 .9984 time (hrs) 7 .90 7.67 7 .24 7 .43 Feah 1.559E-03 2 .358E-03 2 .233E-03 1 .934E-03 1 .315E-03 3.040E-03 Febh 1 .268E-03 1.916E-03 1 .810E-03 1.567E-03 1 .066E-03 2.464E-03 Feah{bc) 9 .204E-04 7 .958E-04 4 .968E-04 1 .603E-03 Febh{bc) 7.484E-04 6 .428E-04 3 .997E-04 1.297E-03 Feah/hr{bc) 1.165E04 1.038E-04 6 861 E-05 2.156E-04 Febh/hr{bc) 9.474E-05 8.384E-05 5.519E-05 1.745E-04 Problems Table 38 Pyrite oxidation in seawater (10-29-86) CUVET R1 BLK R2BLK R3 R4 R5 R6 A593nm 0.0139 0.0229 0 .0400 0.0406 0.0633 mineral cone 0 .000485 0.000723 0.000529 0 .000652 0.000658 corr. {df) 1 .0462 1.0447 1 .0466 1.0456 1 .0456 corr. (cf) 0 .8529 0.8566 0 .8579 0 .8598 0 .8597 corr. {hf) 0 .9988 0.9986 0.9992 0.9992 0.9993 time (hrs) 7.62 7 .83 7 .98 8 .18 Feah 9 .083E-04 1.002E-03 2.396E-03 1 971 E-03 3 .046E-03 Febh 7 .405E-04 8 .215E-04 1.964E -03 1 .620E-03 2.505E-03 Feah(bc) 1 441 E-03 1.015E-03 2.091 E-03 Febh(bc) 1.183E-03 8 .394E-04 1. 724E-03 Feah/hr(bc) 1.891 E-04 1.298E-04 2.619E-04 Febh/hr(bc) 1 .553E-04 1 .073E-04 2.159E-04 Problems R6 weight problem

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APPENDIX 5 (Continued) 114 Table 39 Pyrite oxidation in seawater (11-8-86) aJVET R1 R3 R4BLK R5 R6 BLK A593nm 0 .1349 0.1656 0.1431 0 .1684 0.0978 mineral cone 0 .001312 0.001585 0.001367 0 .002014 0 .001406 corr. (df) 1 .0463 1 .0478 1.0463 1 .0460 1 .0456 corr. (cf) 0.8495 0.8331 0 .8488 0.8487 0.8508 corr. (hf) 0.9986 0.9980 0.9993 0.9942 0.9989 time (hrs) 6.99 7.14 7 .31 Feah 3 .390E-03 3 .446E-03 3.453E-03 2.743E-03 2 .292E-03 Febh 2 .752E03 2 .740E-03 2.801 E-03 2 .226E-03 1.865E-03 Feah(bc) 5.173E-04 5.733E-04 -1.296E-04 Febh(bc) 4.191 E-04 4 .067E-04 -1.075E-04 Feah/hr(bc) 7.400E-05 8 .028E-05 -1.773E-05 Febh/hr(bc) 5 .994E-05 5.694E-05 -1.470E-05 Problems R5 solution loss Table 40 Pyrite oxidation in seawater (11-9-86) CUVET T1 T2 BLK T4 T5 T7 A593nm 0 1371 0.0673 0 .1525 0.1066 0 .1825 mineral cone 0 001591 0.001389 0.001713 0 .001929 0 .002046 corr. (df) 1 .0457 1.0454 1.0462 1.0464 1.0460 corr. (cf) 0 .8484 0 .8489 0.8453 0.8457 0.8468 corr. (hf) 0 .9989 0 .9972 0 .9975 0 .9994 0.9975 time (hrs) 7 .58 7.72 7.90 8 .07 Feah 2.874E-03 1.613E-03 2 .966E-03 1.845E-03 2.972E03 Febh 2.332E-03 1.31 OE-03 2.396E-03 1.491 E-03 2.406E-03 Feah(bc) 1.249E-03 1.340E-03 2.194E-04 1.346E-03 Febh(bc) 1.015E-03 1 .079E-03 1 737E-04 1.089E-03 Feah/hr(bc) 1 .647E-04 1 737E-04 2 77BE-05 1.669E-04 Febh/hr(bc) 1.33BE-04 1.398E-04 2 19BE-05 1.349E-04 Problems

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APPENDIX 5 (Continued) 115 Table 41 Pyrite oxidation in 7% 02 (11-16-86) CUVET R1 R3 BLK R4 R5BLK R7 A593nm 0 .0106 0.0100 0.0119 0 .0194 0 .0203 mineral cone 0 .000883 0.000737 0.000621 0 .000741 0 .000485 carr. (df) 1 .0457 1.0456 1.0452 1 .0448 1 0451 carr. (cf) 0 .8639 0 .8626 0.8666 0 .8672 0.8659 carr. (hf) 0 .9455 0 .9970 0 .9992 0 9851 0 .9989 time (hrs) 3 .92 4 08 16.78 Feah 3 .844E04 4.579E-04 6 .477E-04 8 728E-04 1.414E-03 Febh 3 .175E-04 3.777E-04 5.371 E-04 7.245E-04 1.171E-03 Feah(bc) -2.81 OE-04 -1.760E-05 7 .486E-04 Febh(bc) -2.336E-04 -1.403E-05 6.203E-04 Feah/hr(bc) -7.174E-05 -4.320E-06 4.460E-05 Febh/hr(bc) -5 .964E-05 -3.443E-06 3 .696E-05 Problems R1 boil over Table 41 continued CUVET T2 T4 T5 T7 A593nm 0.0563 0.0653 0 .0563 0 .0662 mineral cone 0.000572 0.000657 0 .000753 0 .000782 corr. (df) 1 .0447 1 .0450 1 .0453 1.0454 carr. (cf) 0 .8664 0.8663 0.8660 0 .8642 carr. (hf) 0 .9980 0.9989 0.9988 0.9971 time (hrs) 16.84 21.35 21.51 21.83 Feah 3 .324E03 3.360E-03 2 .528E-03 2.857E-03 Febh 2. 757E-03 2. 786E-03 2 .095E03 2 .362E-03 Feah(bc) 2.659E03 2.695E-03 1.863E-03 2 191 E 03 Febh(bc) 2 .206E-03 2 .235E-03 1 .544E-03 1 811E-03 Feah/hr(bc) 1 .579E-04 1.262E-04 8.661 E-05 1 .004E-04 Febh/hr(bc) 1 31 OE-04 1.047E-04 7 .177E-05 8 .296E-05 Problems

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APPENDIX 5 (Continued) 11 6 Table 42 Pyrite oxidation in 7% 02 (11-19-86) CUVET R1 R3 R4 AS R7 A593nm 0.0120 0 .0524 0 0571 0.1423 0 .0616 mineral cone 0.000546 0 .000462 0.000700 0 .000735 0.000533 corr. (df) 1.0453 1.0460 1 .0450 1 .0447 1 .0453 corr. (cf) 0.8646 0 .8638 0 .8653 0 .8657 0 .8645 corr (hf) 0.9993 0 .9992 0.9989 0 .9987 0 .9965 time (hrs) 22.35 22.48 22.98 23.30 24.30 Feah 7 .475E-04 3 .866E-03 2.775E-03 6 .583E-03 3 .924E-03 Febh 6 .182E-04 3.192E-03 2.298E-03 5.455E-03 3 .246E-03 Feah(bc) 2.903E-04 3.408E-03 2.318E-03 6 .126E-03 3 .469E-03 Febh(bc) 2 .403E-04 2 .814E-03 1.920E-03 5.077E-03 2 .869E-03 Feah/hr(bc) 1 .299E-05 1 .516E-04 1.009E-04 2.630E-04 1 .428E-04 Febh/hr(bc) 1 .075E-05 1 .252E-04 8.354E-05 2.179E-04 1.181E-04 Problems R1 lost R7 boil pyrite over sample Table 42 continued CUVET T2 BLK T4 T5 BLK T7 A593nm 0 .0040 0.0177 0.0116 0 .0429 mineral cone 0.000417 0 .000332 0.000676 0.000748 corr. (df) 1 .0450 1 .0454 1.0453 1.0453 corr. (cf) 0.8652 0 8641 0 .8660 0.8639 corr (hf) 0 .9977 0.9996 0 .9992 0 .9980 time (hrs) 24.55 24.71 Feah 3.260E04 1.814E-03 5.842E-04 1 .949E-03 Febh 2.699E-04 1 .500E-03 4.839E-04 1 .611E-03 Feah(bc) 1 .357E-03 1.494E-03 Febh(bc) 1 .122E-03 1.233E-03 Feah/hr(bc) 5 .527E-05 6 .045E-05 Febh/hr(bc) 4.568E-05 4 .989E-05 Problems

PAGE 138

APPENDIX 5 (Continued) 117 Table 43 Pyrite oxidation in 7% 02 (12-5-86) CUVET T2 T4 T5 T7 BL K T8 A593nm 0 .0609 0 .0739 0 .0274 0.0351 0 .0329 m i nera l cone 0 .001184 0 .000800 0 .000727 0 .001100 0 .000579 corr. (df) 1 .0446 1 .0452 1 .0455 1.0454 1 .0444 corr. (cf) 0.8662 0 .8638 0.8621 0.8644 0.8681 corr. (hf) 0.9989 0 .9994 0 .9905 0.9769 0 .9995 time (hrs) 23.66 20.57 20.02 19.78 Feah 1.742E-03 3.131E-03 1.266E-03 1.057E-03 1.925E-03 Febh 1 .444E-03 2 .587E-03 1 .044E-03 8 .741E-04 1 .600E-03 Feah(bc) -1.016E-04 1.287E-03 -5.772E-04 8.161 E-05 Febh(bc) -8.040E-05 1 .063E-03 -4.806E-04 7 .540E-05 Feah/hr(bc) -4.293E-06 6 .259E-05 -2.883E-05 4 .126E-06 Febh/hr(bc) -3.398E-06 5 .167E-05 -2.400E-05 3.812E-06 Problems T5 spilt solution Table 43 continued CUVET R1 R3 R4 R5BLK R7 A593nm 0.0736 0 .0432 0 .0733 0.0557 0.0411 mineral cone 0 .000931 0 .000889 0 .000782 0 .000717 0.000658 corr. (df) 1.0454 1 .0456 1 .0453 1.0450 1 .0452 corr. (cf) 0.8638 0 .8634 0.8658 0 .8645 0.8650 corr. (hf) 0.9949 0 .9993 0 .9992 0.9987 0.9991 time (hrs) 23.34 23.18 20.12 19.45 Feah 2 .668E-03 1 .648E-03 3 .177E-03 2 .629E-03 2.117E-03 Febh 2 .205E-03 1.361 E-03 2 .632E-03 2.175E-03 1.752E-03 Feah(bc) 8.252E-04 -1.955E-04 1 .334E-03 2 .734E-04 Febh(bc) 6 .802E-04 -1.640E-04 1 1 07E-03 2.271 E-04 Feah/hr(bc) 3.536E-05 -8.433E-06 6.632E-05 1 .406E-05 Febh/hr(bc) 2 .915E-05 -7.073E-06 5 .502E-05 1.168E05 Problems R1 spilt R3 problem solution with weight

PAGE 139

APPENDIX 5 (Continued) 118 Table 44 Pyrite oxidation at low temperature (1-14-87) aJVET R1 blk R3 R4 AS blk R7 R9 A593nm 0.0808 0 1137 0 .0666 0 1 080 0 .1648 0.0818 mineral cone 0.001556 0.002104 0.001735 0 .002356 0.001691 0.001660 corr. (df) 1 .0457 1.0463 1 .0452 1.0451 1 .0456 1 .0456 corr. (cf) 0 .8609 0 .8536 0 .8663 0 .8639 0.8652 0.8639 corr. (hf) 0.9989 0 .9978 0 .9992 0 .9906 0 .9993 0.9991 time (hrs) 55.59 53.60 54.17 53.24 Feah 1 .874E-03 1 .950E-03 1 .386E-03 1.640E-03 3.520E-03 1 .779E-03 Febh 1.543E-03 1 591 E-03 1 .148E-03 1 .356E-03 2.912E-03 1.470E-03 Feah(bc) -3.059E-04 -8. 702E-04 1.264E-03 -4.770E-04 Febh(bc) -2. 729E-04 -7.152E-04 1 .049E-03 -3.940E-04 Feah/hr(bc) -5.502E-06 -1.623E-05 2.334E-05 -8.959E-06 Febh/hr(bc) -4.909E-06 -1.334E-05 1.936E-05 -7.400E-06 Problems R3 cap loose during incubat i on Table 44 continued aJVET T2 T4 T5 T7 T8 T9 blk A593nm 0 .11 08 0 .2493 0.2070 0.2532 0.2153 0 2561 mineral cone 0.001840 0 .003450 0 .002649 0.002882 0 .003466 0 .002838 corr. (df) 1.0445 1 .0452 1.0458 1.0455 1.0446 1 .0450 corr. (cf) 0.8664 0 .8646 0.8630 0.8631 0 .8670 0 .8649 corr. (hf) 0 .9983 0.9861 0 .9823 0.9985 0 .9982 t i me (hrs) 54.94 54.42 56.01 68.64 70.08 Feah 2.171 E-03 2 .574E-03 2 .774E-03 3 .170E-03 3 .253E-03 Febh 1.801 E-03 2 .129E-03 2 .289E-03 2.617E-03 2 .692E-03 Feah(bc) -8 .502E-05 3.185E-04 5 .184E-04 9.141E-04 Febh(bc) -6 31 OE-05 2 .659E-04 4 .256E-04 7.531 E-04 Feah /hr(bc) -1.548E-06 5 .853E-06 9 .255E-06 1.332E-05 Febh/hr(bc) -1.149E-06 4 .885E-06 7 .599E-06 1 .097E-05 Problems T8 weight missing

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APPENDIX 5 (Continued) 11 9 Table 45 Pyrite oxidation at low temperature (1-19-87) CUVET R1 R3 BLK R4 R5 R7 R9 A593nm 0.0304 0 .0402 0.0392 0 .1036 0 .0692 0.0782 m i nera l cone 0 .001446 0 .001440 0 .002255 0 .001683 0.001641 0 .001767 corr. (df) 1.0456 1 .0459 1 .0453 1 .0453 1.0455 1 .0454 corr. (cf} 0 .8646 0 .8619 0 .8661 0.8640 0 .8650 0 8651 corr. (hf) 0.9991 0 .9982 0 .9994 0.9985 0.9986 0.9992 time (hrs) 55.13 56.62 55.77 55.42 56.08 Feah 5 .659E-04 7 .51 OE-04 4 .680E04 1 .656E-03 1 .134E-03 1.191E-03 Febh 4 .679E-04 6 .188E-04 3 .878E-04 1 .369E-03 9.385E-04 9 .855E-04 Feah(bc ) 8.730E-05 -1.056E-05 1.177E-03 6 .559E-04 7 .124E-04 Febh(bc) 7.214E-05 -8.024E-06 9 .728E-04 5.427E-04 5 .897E-04 Feah/hr(bc) 1.583E-06 -1.865E-07 2 111 E-05 1 .184E-05 1.270E-05 Febh/hr(bc) 1.308E-06 -1.417E-07 1.744E-05 9 794E-06 1.052E-05 Problems R1 lost sample Table 45 continued CUVET T2 T4 BLK T5 T7 T8 BLK T9 A593nm 0 .0460 0 .0382 0 .0513 0 .0793 0 .0239 0 .0792 mineral cone 0.001363 0.002779 0.002507 0.002773 0 .002038 0 .003385 corr. (df) 1.0447 1.0451 1.0456 1 .0452 1.0445 1 .0450 corr. (cf) 0.8624 0 .8672 0 .8508 0 .8741 0 .8681 0 .8669 corr. (hf) 0.9979 0 .9988 0 .9988 0.9988 0 .9978 0 .9985 time (hrs) 54.72 57.26 56.90 57.58 Feah 9 .066E-04 3 .697E-04 5.507E-04 7.693E-04 3 .150E-04 6.290E-04 Febh 7.484E-04 3.068E-04 4.481 E -04 6 .434E-04 2 .618E-04 5 .218E-04 Feah(bc) 4.281 E-04 7 .218E-05 2 .908E-04 1.505E-04 Febh(bc) 3.526E-04 5.230E-05 2.476E-04 1.260E-04 Feah/hr(bc) 7.823E-06 1 261 E -06 5 .11 OE-06 2 .613E-06 Febh/hr(bc) 6.444E-06 9.134E-07 4.351 E-06 2 188E-06 Problems T2 T5 cap con tam blew off -ina ted during heat ing

PAGE 141

APPENDIX 5 (Continued) 120 Table 46 Pyrite oxidation at low temperature (1-25-87) CUVET R3 R4 BLK R5 R7 R9 BLK A593nm 0 .0902 0 .1365 0.1089 0 .0877 0 .0423 mineral cone 0 .001118 0 .001657 0.002399 0 .001929 0 .002639 corr. (df) 1.0459 1.0454 1.0448 1 .0454 1 .0452 corr. (cf) 0.8637 0 .8636 0.8655 0 .8626 0.8648 corr. (hf) 0.9994 0.9990 0 .9989 0.9985 0 .9995 time (hrs) 71.03 73.10 70.68 Feah 2.895E-03 2 .954E-03 1.628E-03 1.630E-03 5 .750E-04 Febh 2 391 E -03 2 441 E-03 1.348E-03 1.345E-03 4 .758E-04 Feah(bc) 2 .173E-03 9 .050E-04 9 .078E-04 Febh(bc) 1.794E-03 7.508E-04 7.478E-04 Feah/hr(bc) 3.059E-05 1.238E-05 1.284E-05 Febh/hr(bc) 2 .526E-05 1.027E-05 1.058E-05 Problems R4 blk contaminant Table 46 continued CUVET T2 T4 T5 T7 T8 BLK T9 A593nm 0 .1280 0.0562 0.0793 0 .1036 0 .0324 0 .0578 mineral cone 0.003050 0 .002177 0.001897 0.001966 0 .001335 0 .001779 corr. (df) 1 .0448 1 .0452 1 .0455 1.0454 1.044 7 1 .0451 corr. (cf) 0.8636 0.8656 0.8631 0 .8649 0 .8635 0 .8632 corr (hf) 0.9979 0 .9988 0.9897 0 .9989 0 .9990 0 .9983 t i me (hrs) 73.39 72.74 71.64 72.00 71.28 Feah 1 .503E-03 9 .258E-04 1 .486E-03 1 .890E-03 8 .701 E-04 1.164E-03 Febh 1 .242E-03 7 .667E-04 1 .227E-03 1.564E-03 7 191 E-04 9.616E-04 Feah(bc) 7.801 E 04 2.033E-04 7.634E-04 1.168E-03 4.418E-04 Febh(bc) 6 .446E-04 1.692E-04 6 .292E-04 9.665E-04 3.642E-04 Feah/hr(bc) 1.063E-05 2.794E-06 1 .066E-05 1 .622E-05 6.199E-06 Febh /hr(bc) 8 .783E-06 2.326E-06 8 .783E-06 1 .342E-05 5 1 09E-06 Problems T5 spilt solution

PAGE 142

APPENDIX 5 (Continued) 121 Table 47 Pyrite oxidation at high pressure (2-19-87) Type min bl k min blk min blk min blk SWblk SWblk Tube 1 ( 1 ) 7(2) 1 0(3) 15(4) 1 7(5) 20(6) A593nm 0 .0317 0.0285 0.0296 0.0291 0 .0818 0.0234 A593nm sbc 0 .0091 0 .0059 0.0070 0.0065 0.0008 mineral cone 0 .005417 0 .002718 0 .004320 0 .011015 0.000000 0.000000 corr. (df) 13.3112 11.9428 12.1648 13.7597 13.1281 15.4897 time (hrs) Fe 7.580E-04 8.770E-04 6.674E-04 2. 748E-04 Fe( be) Fe/hr(bc) Problems 7 (2) m i n blk 17(5) sample lost contaminant Table 47 continued Type test test test test SWblk Tube 3 (7) 6 (8) 8 (9) 11 (1 0) 18(11) A593nm 0.0321 0.0410 0.0409 0.0356 0 .0220 A593nm sbc 0.0095 0.0184 0.0183 0.0130 mineral cone 0.006885 0.010481 0 .010900 0.008697 0 .000000 corr. (df) 10.7117 11.8249 11.2815 11.4783 12.2815 time (hrs) 24.06 23.03 23.10 23.07 Fe 5 .01 OE-04 7.050E-04 6.432E-04 5.822E-04 Fe( be) -6.570E-05 1.383E-04 7.644E-05 1.545E-05 Fe/hr(bc) -2. 731 E-06 6 .004E-06 3.309E-06 6.695E-07 Problems 6(8) lost 11 (1 O)lost solution solution

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APPENDIX 5 (Continued) 122 Table 47 continued Type SWblk test test test test Tube 19(12) 9 (13) 12 (14) 13 (15) 14 ( 16) A593nm 0 .0225 0.0442 0 .0422 0 .0411 0 .0343 A593nm sbc 0.0216 0 .0196 0.0185 0 .0117 mineral cone 0.000000 0 .010672 0 .008240 0.007582 0 .003853 corr. (df) 11.6522 14.1922 13.3432 12.6613 13.3387 time (hrs) 46.93 46.98 47.04 47.09 Fe 9 758E-04 1.078E-03 1 .049E-03 1 .374E-03 Fe(bc) 4 .090E-04 5.113E-04 4 .824E-04 8 .074E-04 Fe/hr(bc) 8 717E-06 1 .088E-05 1.026E-05 1. 714E-05 Problems Table 48 Pyrite oxidation at high pressure (2-23-87) Type min blk min blk min blk SWblk SWblk test Tube 5( 1) 11 (2) 13(3) 16( 4) 20(5) 2 (6) A593nm 0.0358 0.0341 0 .0305 0.0257 0.0267 0.0485 A593nm sbc 0 .0096 0 .0079 0.0043 0.0194 mineral cone 0.015564 0.008450 0.005522 0.000000 0.000000 0 .016851 corr. (df) 21.6751 21.3341 21.4989 21 .9703 21.0847 20.2563 time (hrs) Fe 4.565E-04 6.81 OE-04 5.716E-04 7.962E-04 Fe(bc) 2.265E-04 Fe/hr(bc) 5.344E-06 Problems

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APPENDIX 5 (Continued) Table 48 continued Type test test Tube 7 (7) 8 (8) A593nm 0 .0396 0 .0357 A593nm sbc 0 .0105 0 .0066 mineral cone 0 .009470 0.005436 corr. (df) 23.6270 20.6705 time (hrs) 42.43 42.44 Fe 8.944E04 8.569E-04 Fe( be) 3.247E-04 2 .872E-04 Fe/hr(bc) 7.654E-06 6. 766E-06 Problems Table 48 continued Type test SWblk Tube 15 (13) 17 (14) A593nm 0.0339 0 .0287 A593nm sbc 0.0048 mineral cone 0.005417 0.000000 corr. (df) 20.5789 22.1899 time (hrs) 43.42 Fe 6.226E-04 Fe( be) 5.290E-05 Fe/hr(bc) 1 .218E-06 Problems 123 test test test test 9 (9) 14 (1 0) 1 ( 11) 12(12) 0 .0350 0 .0322 0.0408 0.0428 0 .0059 0 .0031 0 .0117 0.0137 0 .006494 0.003405 0 .011568 0.005875 25.1442 24.6110 21.5812 15.7025 42.46 42.54 43.24 43.36 7. 799E-04 7.651E-04 7 .453E-04 1 .250E-03 2.1 02E-04 1 .954E-04 1 .755E-04 6 .806E-04 4 .950E-06 4 .593E-06 4 .059 E-06 1.570E-05 14(10) lost solution SWblk test 18 (15) 4 (16) 0 .0295 0.0452 0.0161 0.000000 0.010843 16.1281 17.3593 43.27 8.800E-04 3.1 03E-04 7.172E-06

PAGE 145

APPENDIX 5 (Continued) 124 Table 49 Pyrite oxidation at high pressure (2-28-87) Type min blk min blk min blk min blk SWblk SWbl k test Tube 3 (1) 5 (2) 11 (3) 13 (4) 20 (5) 17 (6) 6 (7) A593nm 0 .0417 0.0381 0.0360 0 .0338 0 .0319 0 .0309 0 .0615 A593nm sbc 0 .0103 0.0067 0 .0046 0 .0024 0 .0207 mineral cone 0 .114631 0 .009899 0 .004902 0 .006132 0.000000 0 .000000 0 .008678 corr. (df) 18.5606 18.4371 18.1190 17.3730 19.5400 18.6316 16.1693 time (hrs) 92.27 Fe 5 .362E-05 4 .012E-04 5 .467E-04 2 .186E-04 1 .334E-03 Fe( be) 1 .029E-03 Fe/hr(bc) 1 .116E-05 Problems Table 49 continued Type test test test test test test Tube 7 (8) 9 (9) 12 (1 0) 14 ( 11) 15 (12) 1 (13) A593nm 0 .0602 0 .0494 0 .0492 0 .0465 0.0522 0 .0721 A593nm sbc 0 .0194 0 .0086 0 .0084 0.0057 0 .0114 0 .0313 mineral cone 0.008602 0.004921 0 .003195 0 .003080 0 .004959 0 .017967 corr. (df) 17.4211 18.6865 17.0503 20.4005 18.0320 17.7803 time (hrs) 92.28 92.29 92.32 92.33 92.34 93.44 Fe 1 .359E-03 1 .130E-03 1.551 E-03 1 .306E-03 1.434E-03 1 .072E-03 Fe(bc) 1.054E-03 8 .248E-04 1.246E03 1 001 E-03 1.129E-03 7.666E-04 Fe/hr(bc) 1 142E-05 8 .937E-06 1 .350E-05 1.084E-05 1.223E-05 8.204E-06 Problems 12(1 0) lost solution

PAGE 146

APPENDIX 5 (Continued) 125 Table 49 continued Type test test test SWblk SWblk SWblk Tube 2 (14 ) 4 ( 15) 1 0(16) 16 (17) 18 (18) 19 ( 19) A593nm 0 .0549 0 .0585 0.0556 0 .0405 0 .0414 0 .0405 A593nm sbc 0.0141 0 .0177 0.0148 mineral cone 0.007305 0 .008430 0.007219 0 .000000 0 .000000 0.000000 corr. (df) 17.7323 19.9886 17.7895 17.9657 17.9954 18.2609 time (hrs) 93.45 93.47 93.52 93.58 93.59 93.61 Fe 1.184E-03 1.452E-03 1 .262E-03 Fe(bc) 8 .790E-04 1 .147E-03 9 .567E-04 Fe/hr(bc) 9 .407E-06 1.227E-05 1 .023E-05 Problems 4(15)1ost solution Table 50 Pyrite oxidation at high pressure (3-10-87) Type SWbl k SWblk min blk min blk min blk SWblk SWblk Tube 15 ( 1) 19 (2) 10 (3) 6 (4) 2 (5) 18 (6) 17 (7) A593nm 0.0209 0.0214 0.0242 0.0279 0.0320 0.0189 0 .0209 A593nm sbc 0 .0031 0.0068 0 .0109 mineral cone 0 .000000 0.000000 0.003300 0.006590 0 .005131 0 .000000 0.000000 corr. (df) 14.3661 13.7162 13.4371 13. 1831 14.1991 13.1785 12.2815 time (hrs) 45.67 45.64 Fe 3 .959E-04 4.304E-04 9 571 E -04 Fe(bc) Fe/hr(bc) Problems

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APPENDIX 5 (Continued) 126 Table 50 continued Type test test test test test SWbl k Tube 13 (8) 12 (9) 9 (1 0 ) 7 (11) 3 ( 1 2 ) 16 ( 1 3 ) A593nm 0 .0241 0 .0248 0 .0262 0 .0280 0.0237 0 .0197 A593nm sbc 0 .0043 0 .0050 0 .0064 0.0082 0.0039 m i ne r al cone 0 .003233 0 .003538 0.003300 0 .006247 0 .00374 8 0 .000000 carr. (df) 12.5995 13.6636 13 .3936 16.9428 17. 1121 16.3936 time (hrs) 45. 62 45.57 45. 54 45.52 45.46 48.12 Fe 5 .300E-04 6.114E-04 8 .237E-04 7 .061 E-04 5 .627E-04 Fe( be) -6.445E-05 1 .690E-05 2 .293E-04 1 .116E-04 -3.174E-05 Fe/hr(bc) -1.413E-06 3 .709E-07 5 .034E-06 2 451 E-06 6 .983E-07 Problems Table 50 continued Type test test test test test test Tube 14 ( 1 4) 11 (15) 8 (16) 5 (17) 4 (18) 1 (19) A593nm 0 .0257 0 0311 0 0281 0 .0260 0.0331 0.0545 A593nm sbc 0 .0059 0 .0113 0.0083 0 .0062 0 .0133 0.0347 mineral cone 0 .002718 0 .005045 0 .004616 0 .005388 0 .007734 0 .015221 carr (df) 11.9062 13.5606 13.4943 14.6293 13.4165 13.6773 t ime (hrs) 48.09 48.06 48.03 47 .99 47.99 47.97 Fe 8 .192E-04 9 .653E-04 7 .703E-04 5 .337E-04 7 .336E-04 9.930E-04 Fe(bc) 2 .247E-04 3 .708E-04 1.759E-04 -6.080E-05 1 391 E-04 3 .985E-04 Fe/hr(bc) 4 .672E-06 7 .716E-06 3 .662E-06 -1.267E-06 2 .898E-06 8 .307E-06 Problems Calculations for (summary ) Tables All individu a l test results with a problem noted in Tables 15 50, have been omitted from the following summary tables. The listed values for oxidation rate have been converted f rom Fe t otal (moles) I FeS2(moles initially present)lhour to Fe total (moles) I FeS2(m2 initially present)lhour using the results of the BET analyses

PAGE 148

APPENDIX 5 (Continued) 127 The specific surface area of pyrite was 0.1338 0 021 m2/g, and for marcasite, it was 0.3509 0 025 m2/g. The value "mean of all cuvets" for each study, which is the mean of the oxidation rates (Febh/hr) in Tables 15 50, has been included in Tables 3 and 4 This allowed each individual test result to be equally weighted since the number of individual tests in an experiment varied. However as can be seen in these tables, the mean of all cuvets was essentially the same as the mean of experiment means. pH correction The values for pH listed in the summary worksheets for experiments performed at high pressure (study 5) were measured at 25C and 1 bar. The pH listed in Tables 3 and 4 for study 5 has been corrected to show pH under conditions of incubation. To correct to pH at 3.3C, the following equation was used: where x is -0.0111 and t is temperature C, (Riley and Chester, 1979 ) The corrected pH at 207 bars is then determined from Table 6.1 (Ibid, pg. 131 ).

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APPENDIX 5 (Continued) 128 Outliers There were two outliers omitted from Study 1 for pyrite and study 4 for marcasite which were both greater than 3 standard deviations from the experimental mean. Tables 54 and 56 include results with and without these outliers However, the values listed m Tables 3 and 4 are those from which the outliers have been omitted Negative values for oxidation rates have been averaged into experimental means. Such values occurred with exceptionally high blanks that were probably contaminated It is assumed that the same type of contamination also occasionally occurred with test samples; therefore, omission or setting negative rates to zero would bias the results A negative test value could also occur if an exceptionally large mineral particle (lower specific surface area) was part of the pyrite test sample distorted the results. This effect can not be corrected; it can be lessened by including as many experiments as possible. Table 61 presents a summary of the mineral blanks for each study. These values illustrate the average amount of iron found in the mineral blanks, iron present on the mineral surface prior to the experiment (pre-experiment oxidation products). These values were not used in calculating oxidation rates; the mineral blank subtracted from the test results was the average value determined for the

PAGE 150

APPENDIX 5 (Continued) 1 2 9 particular experiment (eg experiment 1 0-4-86 ). This was done to avoid error from inconsistencies in the cleaning procedure

PAGE 151

APPENDIX 5 (Continued) 1 3 0 Table 51 Summary of marcasite oxidation experiments in 0.7 M NaCI Study 1 Cuvet/exp Feah/hr* Febh/hr* pH Initial time hrs A4/ 1 0/S/86 7 .610E-06 6.168E-06 7 .886 S.S6 AS 4 .81SE-06 3.9S6E-06 7 .8S3 S .73 A6 7.2S3E-06 S.926E-06 7.88S S 91 T4/ 1 0/8/86 9.863E-06 7.666E-06 7.762 S.62 TS 1.SS4E-OS 1 .170E-OS 7 .767 S .83 T6 1 .1 09E-OS 8.3S7E-06 7.778 6.00 AS/ 1 0/10/86 1 .303E-OS 1.060E-OS 7.824 7 .17 A6 1.2SOE-OS 1 .018E-OS 7 .8S7 7.47 T1 I 10/4/86 2.779E-06 2 .273E-06 7.826 4 .62 T2 4.4S3E-06 3.SS6E-06 7 .809 4.77 T4 2.488E-06 1.974E-06 7 .881 7 .9S Experiment Means 10/4/86 3 .240E-06 2 601 E-06 7.839 S .78 1 0/S/8 6 6 .SS9E-06 S.3SOE-06 7 .87S S.73 1 0 /8/8 6 1 .217E-OS 9.242E-06 7.769 S.82 10/10/86 1 .276E-OS 1.039E-OS 7.841 7 .32 Mean of exp. means 8.682E-06 6.89SE-06 7.831 6 .16 Standard deviation 4 .S80E-06 3 .S84E-06 0 .044 0 .77 Mean of all cuvets 8 311 E-06 6 .S78E-06 7.830 6 .06 Standard deviation 4 421 E-06 3.407E-06 0 .047 1.06 P. standard deviation 4 .216E-06 3.248E-06 0.04S 1. 01 Standard error 1.271 E-06 9.794E-07 0.013 0 .30

PAGE 152

APPENDIX 5 (Continued) 131 Table 52 Summary of marcasite oxidation experiments in seawater Study 2 Cuvet/exp Feah/hr* Febh/hr* pH Initial time hrs T4/ 10/31/86 3 .131E-07 2. 706E-07 7 .334 8.01 T5 -2.516E-07 -2.268E-07 7 .333 8 .14 T6 1.476E-05 1 .200E-05 7.300 8 31 T7 9.819E-07 7 .353E-07 7 .310 8 .56 R2/ 11/3/86 1.523E-05 1.246E-05 7 .769 7 .93 R3 9.060E-06 7 .317E-06 7 .742 8 .17 R6 1 .41 9E-05 1 .153E05 7 .818 8 .35 T1/ 11/4/86 5.618E-06 4 .546E-06 7.710 8.43 T2 8.693E-06 7 051 E-06 7 .694 8 .55 T4 3 .020E-06 2 .405E-06 7 .725 8 71 T5 8 .387E-06 6 .745E-06 7 731 8.83 R3/ 11/13/86 6.439E-06 5 .318E-06 7 .456 16.29 R4 5 711 E-06 4 .725E-06 7 .505 16.4 7 T2 4 .750E-06 3.956E-06 7.421 16.79 T4 4.526E-06 3. 740E-06 7.467 16.95 Experiment Means 10/31/86 3 .952E-06 3 .194E-06 7 .319 8 .25 11/3/86 1.283E-05 1 .044E-05 7 .776 8 .15 11/4/86 6 .429E-06 5 .187E-06 7 .715 8 .63 11/13/86 5 .356E-06 4.435E-06 7 .462 16.63 Mean of exp. means 7 .141E-06 5 .813E-06 7 .568 10.41 Standard deviation 3 .923E-06 3 .189E-06 0 .215 4 .15 Mean of all cuvets 6 .762E-06 5 .505E-06 7 .554 10.56 Standard deviation 5 .016E-06 4 .086E-06 0 .192 3.79 P. standard deviation 4.846E-06 3.947E-06 0.185 3.66 Standard error 1.251 E-06 1 .019E-06 0.048 0 .95

PAGE 153

APPENDIX 5 (Continued) 132 Table 53 Summary of marcasite oxidation experiments in 7% 02 Study 3 Cuvetlexp Feah/hr* Febh/hr* pH Initial time hrs R1 I 121 13 /86 1.645E-06 1 .357E-06 8.055 20.82 R7 3 .919E-06 3 .236E-06 8 .119 21.14 R9 3 .174E-06 2 .627E-06 8.108 25. 15 T2 4 .987E-06 4.143E-06 8.088 20.89 T4 3.418E-06 2.835E-06 8.103 20.50 T7 3 .190E06 2 .647E-06 8 .125 24.62 T8 4 752E-06 3 931 E-06 8 .093 24.90 T9 5 .165E-06 4 .277E-06 8.128 24.76 R 1 I 121 17186 2 .654E-06 2.194E-06 8.107 25.96 R3 1 .820E-06 1 .493E-06 8 .123 25.57 R4 2 .862E-06 2 .368E-06 8.125 22.36 R7 4.319E-06 3 .547E-06 8.153 21.86 R9 2 .889E-06 2 .388E-06 8 .154 22.69 T5 1 .550E-06 1 .280E-06 8 .132 26.25 T7 1.266E-06 1 .048E-06 8 .122 25.84 T8 7 .207E-06 5 .975E-06 8 .166 22.30 T9 4 .328E-06 3 .575E-06 8.128 22.13 Experiment Means 12113186 3.781E-06 3 .132E-06 8 .102 22.85 12117186 3 211 E-06 2 .652E-06 8 .134 23.88 Mean of exp. means 3.496E-06 2.892E-06 8.118 23.37 Standard davlatlon 4.034E-07 3.390E-07 0.023 0 .73 Mean of all cuvets 3 .479E-06 2 .878E-06 8.119 23.40 Standard deviation 1.553E-06 1.288E -06 0.027 2.05 P. standard deviation 1.506E-06 1 .249E-06 0.026 1.99 Standard error 3.653E-07 3 .030E-07 0.006 0.48

PAGE 154

APPENDIX 5 (Continued) 133 Table 54 Summary of marcasite oxidation experiments at low temperature Study 4 Cuvet/exp Feah/hr Febh/hr* pH Initial time hrs R3 12/22/86 2 .559E-07 1 .926E-07 7.856 21.88 R4 4 .727E-08 2 .942E-08 7.865 21.42 R5 -6.034E-07 -3 .936E-07 7 8 7 0 22.71 R7 -4.806E-08 -5.454E-08 7.886 23.69 R9 -6.034E-07 -5.126E-07 7.895 22.27 T5 -1.444E-07 -1.334E-07 7 .876 21.96 T8 3 .658E-06 3 .012E-06 7.897 21.55 T9 1.642E-07 1.259E-07 7 .900 23.82 T9 1 / 3 / 87 2 .160E-07 1 .788E-07 8 .066 41.57 R1 1.118E-07 8 .389E-08 8.011 67 .66 R3 -4 .555E-09 -2.599E-08 8.038 41.06 R5 1 .165E-06 9 .645E-07 8 0 4 4 41.7 3 R9 6 .338E-07 5 231 E -07 8 .039 67 .37 R7 1 /31/87 7 .173E-07 5 .945E-07 8.260 55 .58 R9 9 .595E-07 7.971 E-07 8.281 55.27 T2 8 .352E-07 6 .901 E-07 8 .219 54 .9 3 T4 9 .193E-07 7 .624E-07 8.234 54 .53 T5 8.402E07 6 941 E-07 8 .259 53 .49 Experiment means Including T8 12122 186 outlier 12/22/86 3 .408E-07 2 .832E-07 7 881 2 2.41 1/3/8 7 4.244E-07 3 .449E-07 8 .039 51.88 1/31/87 8 .543E-07 7 .077E-07 8.251 54 .76 Mean of exp means 5.398E-07 4.452E-07 8 .057 43.02 Standard deviation 2 .755E-07 2 .293E-07 0.186 17 .90 Mean of all cuvets 5 .067E-07 4.182E-07 8 .028 39.58 Standard deviation 9.428E-07 7 .741 E-07 0.159 17.30 P. standard deviation 9.162E -07 7.523E-07 0.154 16.82 Standard error 2 .160E-07 1.773E-07 0 .036 3.96 Experiment means Excluding T8 12122186 outlier 12/22/86 -1. 331 E-07 -1.066E-07 7 .878 22.53 1 / 3 / 8 7 4 .244E-07 3.449E07 8.039 5 1.88 1/31/87 8 .543E-07 7 .077E-07 8 251 54. 76 Mean of exp means 3 .818E-07 3 .153E-07 8 .057 43.02 Standard deviation 4.951 E -07 4 .079E-07 0.186 17.90 Mean of all cuvets 3 .213E-07 2 .657E-07 8 .035 40. 64 Standard deviation 5 .358E-07 4 .376E-07 0.160 17.22 P. standard deviation 5 .198E-07 4.246E-07 0 .155 1 6 .71 Standard error 1 .261E-07 1 .030E-07 0.038 4.05

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APPENDIX 5 (Continued) 1 3 4 Table 55 Summary of marcasite oxidation experiments under high pressure Study 5 Tube/exp Fe/hr(bc) pH Initial time hrs 1 3 / 7/87 6 331 E-07 8.300 44.95 1 0 6 .890E-07 8 .300 45. 05 1 1 3 .135E-07 8 .300 45.06 5 3 .332E-07 8 .300 46.06 13 3 / 14 / 87 4 .554E-07 8.450 93.62 6 3 .684E-07 8.450 93.53 3 5 .920E-07 8.450 93.48 2 4.946E-07 8 .450 93.48 12 6 .547E-07 8 .450 95.03 9 5 .032E-07 8 .450 95.00 5 5 .353E-07 8.450 94.95 4 3 .893E-07 8 .450 94.93 10 3 /21/87 4 .060E-07 8 .170 93.77 8 3.172E-07 8 .170 93.76 7 2 .030E-07 8 .170 93.75 7 2 701 E-07 8.170 93.74 2 2 782E-07 8.170 93.70 9 4 .424E-07 8.170 94.90 4 3 .493E-07 8 .170 94.86 3 3 .565E-07 8 .170 94.84 10 3 /26/87 1 .812E-07 8 .210 138.32 5 1.898E-07 8 .210 138.24 8 1 .390E-07 8 .210 138.20 4 7 .307E-08 8.210 139.40 1 1 871 E-07 8 .210 139.30 Experiment means 317187 4.922E-07 8.300 45.28 3 /14/87 4 991 E-07 8 .450 94.25 3/21/87 3 .278E-07 8 .170 94. 1 6 3 /26/8 7 1.540E-07 8 .210 138. 69 Mean of exp means 3 .683E-07 8 .283 93.10 Standard deviation 1 .633E-07 0 .124 38.16 Mean of all tubes 3 742E-07 8 .288 95.28 Standard deviation 1 .675E-07 0 121 28.47 P standard deviation 1 641 E-07 0.119 27.89 Standard error 3 281 E-08 0.024 0 .02

PAGE 156

APPENDIX 5 (Continued) 1 3 5 Table 56 Summary of pyrite oxidation experiments in 0 7 M NaCI Study 1 Cuvet/exp Feah/hr* Febh/hr* pH Initial time hrs T4/ 10/13/86 1 .016E-05 8 .148E-06 7 .673 7 .03 T5 1.487E-05 1.187E-05 7 .706 7.16 T6 3.225E-05 2 .600E-05 7.710 7 .39 T7 6.608E-05 5.326E-05 7 .700 7.58 R2/ 10/14/86 1.21 OE-05 9 .969E-06 7 .910 7.41 R3 1.746E-05 1.418E-05 7 901 7.63 R5 6 .943E-06 5 .681 E -06 7.982 7 .78 R6 2 .039E-05 1 .663E-05 7 .960 7 .96 T4/ 1 0/1 6/86 9.276E-06 7 .539E-06 7.882 7 .07 T5 4 .980E-06 4 .000E-06 7.912 7 .23 T6 5.1 06E-06 4.162E-06 7.904 7.40 Experiment means Including T7 10/13/86 outlier 10/13/86 3.084E-05 2.482E-05 7 .697 7.29 10/14/86 1.422E-05 1 .162E-05 7.938 7.69 10/16/86 6.454E-06 5 .234E-06 7.899 7 .23 Mean of exp means 1. 717E-05 1 .389E-05 7 .845 7.40 Standard deviation 1 .246E-05 9 .990E-06 0 .129 0 .25 Mean of all cuvets 1 .815E-05 1 .468E-05 7 .840 7.42 Standard deviation 1 778E-05 1 .432E-05 0 .117 0 .30 P. standard deviation 1 .695E-05 1.365E-05 0 111 0 .28 Standard error 5.111E-06 4.11 6E-06 0 .034 0 .09 Excluding T7 10/13/86 outlier Experiment Means 1 0/13/86 1 .91 OE-05 1.534E-05 7 .696 7 .19 10/14/86 1.422E-05 1 .162E-05 7 .938 7.69 10/16/86 6.454E-06 5.234E-06 7 .899 7 .23 Mean of exp means 1 .326E-05 1.073E-05 7.845 7 .37 Standard deviation 6.376E-06 5.111 E-06 0.130 0.28 Mean of all cuvets 1 .335E-05 1 .082E-05 7.854 7.40 Standard deviation 8 391 E -06 6 771 E-06 0.113 0 31 P. standard deviation 7.960E-06 6.423E-06 0 1 07 0.29 Standard error 2 .517E-06 2 031 E -06 0.034 0 .09

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APPENDIX 5 (Continued) 136 Table 57 Summary of pyrite oxidation experiments in seawater Study 2 Cuvet/exp Feah/hr Febh/hr pH Initial time hrs T2/ 10/28/86 7.241E-06 5.888E-06 7 .900 7 .53 T4 6 451 E-06 5 .211 E-06 7.667 7.60 T5 4 .264E-06 3 .430E-06 7.242 7.61 T7 1 .340E-05 1 .084E-05 7.433 7 .58 R3/ 1 0 /29/86 1.175E-05 9 .652E-06 7 .617 7 .85 R4 8.065E-06 6 .667E-06 7 .825 7.91 R5 1 .628E-05 1 .342E-05 7 .983 7.88 R3/ 11/ 8 /86 4 .599E-06 3 .725E-06 6 .992 7 .72 R1 4 .990E-06 3 .539E-06 7 .142 7 .76 T1/ 11/9/86 1 .024E-05 8.317E-06 7.583 7.74 T4 1 .080E-05 8 .689E-06 7 717 7 .78 T5 1 726E-06 1.366E-06 7.900 7 .75 T7 1 .037E-05 8.387E-06 8.067 7 .74 Experiment means 10/28/86 7 .839E-06 6.343E-06 7.560 7 .58 10/29/86 1 .203E-05 9.913E-06 7.808 7.88 11 /8/86 4 794E-06 3 .632E-06 7 .067 7.74 11 / 9 /86 8 .283E-06 6 .690E-06 7 .817 7.75 Mean of exp means 8 .237E-06 6 .644E06 7.563 7 .74 Standard deviation 2.968E-06 2 .572E-06 0 .352 0.12 Mean of all cuvets 8 .475E-06 6.856E-06 7 621 7.73 Standard deviation 4.126E-06 3.428E-06 0 .335 0.12 P. standard deviation 3 .964E-06 3 .293E-06 0.322 0.11 Standard error 1 .099E-06 9 .134E-07 0 .089 0.03

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APPENDIX 5 (Continued) 1 3 7 Table 58 Summary of pyrite oxidation experiments in 7 % 0 2 Study 3 Cuvet/exp Feah/hr* Febh/hr* pH Initial time hrs R4/ 11/16/86 -2.685E-07 -2.140E-07 8 .116 4 .08 R7 2 772E-06 2.297E-06 8.116 16.78 T2 9 .811E-06 8 .139E-06 8.094 16.84 T4 7 .845E-06 6 .505E06 8.128 21.35 TS 5 .383E-06 4.460E-06 8.114 21.51 T7 6.240E-06 5.156E-06 8.098 21.83 R3/ 11/19/86 9.424E-06 7 781 E-06 8 .048 22.48 R4 6.269E-06 5.192E-06 8 .146 22.98 AS 1.634E-05 1.355E-05 8.179 23.30 T4 3.435E-06 2.839E-06 8.112 24.55 T7 3. 757E-06 3.101 E-06 8.105 24.71 R4/ 12/5/86 4.122E-06 3.420E-06 7.952 20.02 R7 8.738E-07 7.259E-07 7.912 19.78 T2 -2.668E-07 -2.112E-06 7 .953 23.34 T4 3.890E-06 3 211 E-06 7.906 23.18 T8 2.564E-07 2 .369E-07 7 .940 19.45 Experiment means 11/16/86 5 .297E-06 4 391 E-06 8 111 17.06 11/19/86 7.846E-06 6.492E-06 8 .118 23.60 12/5/86 1. 775E-06 1 .096E-06 7 .933 21 .15 Mean of exp means 4.973E06 3 .993E-06 8.054 20.61 Standard deviation 3.048E-06 2 720E-06 0.105 3 .30 Mean of all cuvets 4.993E06 4 .018E-06 8 .057 20.39 Standard deviation 4.388E-06 3.81 OE-06 0.092 4.96 P standard deviation 4.248E-06 3 .689E-06 0 .089 4.81 Standard error 1 .062E-06 9 .224E-07 0.022 1.20

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APPENDIX 5 (Continued) 1 3 8 Table 59 Summary of pyrite oxidation exp eriments at low temperature Study 4 Cuvet/exp Feah/hr* Febh/hr* pH Initial time hrs R4/ 1 /14/ 8 7 1 011 E-06 8.285E-07 8 .398 53. 6 1 R7 1 .454E-06 1.206E-06 8 461 54.1 8 R9 -5. 581 E-07 -4.610E-07 8 .286 53.24 T2 -9 641 E -08 -7.164E-08 8.352 54.94 T4 3.646E-07 3 .043E-07 8.413 54.43 T5 5 .765E-07 4. 734E-07 8.349 56.02 T 7 8.296E-0 7 6 .835E-07 8.428 68.64 R4/ 1 /19/87 -1.162E-08 8.829E-09 8.460 56.62 R5 1 .315E -06 1 08 6 E -06 8.546 55.77 R7 7 .373E-07 6 101 E-07 8.489 55.42 R9 7 .913E-07 6.550E-07 8 490 56.08 T7 3.183E-07 2 .710E-07 8.472 56.90 T9 1.628E-07 1 .363E-07 8.489 5 7.58 R3/ 1/25 /87 1.906E-06 1 .573E-06 8 .175 71.03 R5 7 .712E-07 6 .398E-07 8.189 73.10 R7 8 .002E07 6 .592E 0 7 8.21 8 70.68 T 2 6.622E-0 7 5.471 E-07 8.170 73.39 T4 1.741E07 1.449E0 7 8.159 72.74 T 7 1.01 OE06 8 .362E-07 8.215 72.00 T9 3 .862E-07 3 .183E-07 8.147 71.28 Experiment means 1 /14/87 2 .227E-07 1 .866E-07 8.384 56.44 1/19/87 5.521 E-07 4 .584E-07 8.491 5 6.40 1/25/87 8.157E-07 6 741 E-07 8.182 72.03 Mean of exp means 5 .302E-07 4 .397E-0 7 8 .352 61.62 Standard deviation 2.97 1 E-07 2 .443E-07 0.157 9.01 Mean of all cuvets 5 .291 E-07 4 .388E-07 8 .345 6 1 .88 Standard deviation 6. 706E-07 5.528E-07 0 .137 8.26 P. standard deviation 6.536E-07 5 .388E0 7 0.133 8.06 Standard error 1.462E-07 1 .205E-07 0 .030 1.80

PAGE 160

APPENDIX 5 (Continued) 139 Table 60 Summary of pyrite oxidation experiments under high pressure Study 5 Tube/exp Fe/ h r pH Initial time hrs 3 2 / 19 /87 -1.697E-07 8 .250 24.06 8 2 .056E-07 8 .250 23.10 9 5 .417E-07 8 .250 46.93 12 6 764E-07 8 .250 46.98 13 6 .374E-07 8 .250 47.04 14 1 .066E-06 8 .250 47.09 2 2 /23/ 87 3 321 E-07 8 .235 42.39 7 4 .757E-07 8 .235 42.43 8 4 .205E-07 8.235 42.44 9 3 .077E-07 8 .235 42.46 1 2.523E-07 8 .235 43.24 12 9 755E-07 8 .235 43.36 15 7.573E-08 8 .235 43.42 4 4.457E-07 8 .235 43.27 6 2 /28/ 87 6 .933E-07 8 .395 92.27 7 7.100E-07 8 .395 92.28 9 5.554E-07 8.395 92.29 14 6 .737E-07 8.395 92.33 15 7 .599E-07 8.395 92.34 1 5 .099E-07 8 .395 93.44 2 5 .846E-07 8 .395 93.45 1 0 6.358E-07 8 .395 93.52 13 3 /10/87 8 782E-08 8.290 45.62 12 2 .305E-08 8 .290 45.57 9 3 .129E-07 8 .290 45.54 7 1 .523E-07 8 .290 45.52 3 -4 .340E-08 8 .290 45.46 14 2 .904E-07 8 .290 48.09 1 1 4 .795E-07 8 .290 48.06 8 2 .276E-07 8 .290 48.03 5 -7 .874E-08 8 .290 47.99 4 1 801 E -07 8 .290 47.99 1 5 .163E-07 8 .290 47.97

PAGE 161

APPENDIX 5 (Continued) 140 Table 60 continued Fe/ h r pH Initial time hrs Experiment means 1/14/87 4.928E-07 8.250 39.20 1/19/87 4 1 07E-07 8.235 42.88 1/25/87 6.403E-07 8.395 92.74 3 /10/87 1. 793E-07 8.290 46.89 Mean of exp means 4 .308E-07 8 .293 55.43 Standard deviation 1 .927E-07 0.072 25.07 Mean of all cuvets 4 .042E-07 8.295 55.64 Standard deviation 3 .028E-07 0.062 22.03 P. standard deviation 2 .982E-07 0.061 21.69 Standard error 5.191 E-08 0.011 3.78 Table 61 Summary of average mineral blanks for iron oxidation experiments Study Marcasite number of Pyrite number of Mean Febh blanks Mean Febh blanks umole Fe/m2 umole Fe/m2 1 0.0011 7 0 0014 8 2 0.0026 7 0 0014 7 3 0.0014 5 0.0008 6 4 0.0012 8 0.0010 8 5 0.0010 12 0.0005 13

PAGE 162

141 APPENDIX 6 Initial hydrogen ion evolution experiments The absorbance of solutions containing phenol red, a pH indicator dye, can be used to measure small pH changes in th e solution (Robert-Baldo et al., 1985) A series of experiments were performed in order to determine if phenol red c ould be used to monitor the change in pH as pyrite or marcasite underwent oxidative dissolution, and also to optimize experimental parameters as needed. Experiment 1 A qualitative experiment was performed in order to ascertain if acid, which forms as pyrite or marcasite oxidi z es could cause a change in color of a seawater solution containing phenol red, a pH indicator dye. Two identical beakers were filled with ca. 200 mls of seawater containing 1.0 x 10-3 M phenol red To one of these beakers 0.0255 g of pyrite, (U S G.S sample # TA38-148 ) was added The pyrite sample size fraction was 20-200 j.lm and was not pre washed with acid The beakers were covered and left at room temperature for a week At the end of the incubation period there was no discernable difference in color between the two solutions It had been expected that the seawater/pyrite suspension would have turned from pink to a light pink as acid was relea s ed with di ss olution

PAGE 163

APPENDIX 6 (Continued) 142 of pyrite. The buffering capacity of seawater probably prevented the change in pH and hence color. The results indicated that a solution which is less buffered than seawater was needed in order to facilitate observation of pH changes. A558nm Experiment 2 0 .0241 0.0210 -------,. 0.02 "'- Control ----, Test 0 .019 0 .018 0. 0 .017 0 .016 +-------------t---------'""'1 0 20 40 60 80 100 120 140 160 180 Time (hrs) Figure 8. Experiment Initial hydrogen ion evolution rate 2 Experiment 2. In the second experiment, 17 mls of unbuffered, 0 7 M NaCl (1.5 x I0-5 M phenol red, pH = 7 30) was added to each of two identical 5 em pathlength glass spectrophotometer cells Pyrite (5320J.tm size fraction U.S.G .S. sample #79SK002) was added to one cell only, at a concentration of 0.06 g/1. The absorbance of these cells

PAGE 164

APPENDIX 6 (Continued) 143 was measured over a period of 168 hours at 558 nm, where the peak for the basic form of phenol red is found The results are graphed in Figure 8 Note, A558 nm in the graph is corrected for blank and for baseline drift. These results were not conclusive; there ts no essential difference between the test and control. (The initial absorbance at 558 nm for this experiment is lower than the absorbance found in experiment 3 despite the higher concentration of phenol red, because the pH of the incubating medium was lower.) Experiment 3 Experiment 3 employed 0.7 M NaCl buffered with borate/boric acid (1.0 x I0-4 total boron, pH = 8.0, 3 x I0-6 M phenol red) Seventeen mls of degassed (prepared with boiled deionized water) 0.7 M NaCl was added to 5 em pathlength cells. Pyrite, prewashed with acid, 53-100 Jlm size fraction (U.S G.S. sample #79SK002) was added to one cell at a concentration of 0 6 g/1. The cells were closed to the atmosphere by sealing with fitted caps and parafilm. The absorbance at 558 nm was measured daily for 11 days Results are presented in Figure 9. The absorbance is blank corrected and corrected for baseline drift. The absorbance (pH of the test solution) clearly decreased while the control solution remained stable after a slight drop in absorbance. The higher concentration of pyrite and the use of buffered sodium chloride medium which was protected from carbon dioxide invasion, enabled monitoring of oxidative dissolution of pyrite.

PAGE 165

APPENDIX 6 (Continued) Experiment 3 o.44 0 .42 ' 0.4 0 .38 ." A558nm 0.36 """ ._. _____ ., 0.34 0 .32 0.3 144 0.28 +-----+---..---------:....._--0 50 100 150 200 250 Time (hrs) Figure 9 Initial hydrogen ion evolution rate Experiment 3 Experiment 4. Experiment 4 utilized 0.7 M NaCl buffered with borate/boric acid buffer (1.0 x 10-4 total boron, pH = 8.52, 3 x 10-6 M phenol red) as the incubation media. However, instead of degassing the sodium chloride, the solution was saturated with oxygen gas which was scrubbed of C02 by passing through 3 M NaOH and 0.7 M NaCl solution. A sample (0.6 g/1) of acid-washed pyrite, 53-102 s1ze (U S.G.S sample #79SK002) (0.6 g/1) was added to one of the cells. The results are graphed in Figure 10 which show a faster rate with oxygen saturated incubation media than with degassed media (Figure 9). The initial drop in absorbance of the test relative to the control could also be the result the time lag between addition of the sample to the cell and the initial reading of absorbance.

PAGE 166

APPENDIX 6 (Continued) Exper i ment 4 0.4 0 .35 A558nm 0 .51 0 .45lo----o-----o-o----o 0 3 0.25 Contro l -0 2 0 .15 ............... 0 1 ............... ----- 0 .05 Figure 10 Experiment 0 1 0 20 30 40 50 60 Time (hrs) Initial hydrogen ion evolution rate 4 70 145 After pouring solution into the cells, the pH of the left over sodium chloride solution in the beaker, which had been used for dispensing the solution, had dropped to 7 .2. The pH returned to 8 5 after bubbling with oxygen. This indicated that precautions would have to be taken to ensure that the incubating solution was not exposed to atmospheric C02 during addition to cells. For all experiments, thereafter, incubating solution was bubbled with the appropriate gas, as it was poured into the cell at the beginning of the experiment. Experiment 4a

PAGE 167

APPENDIX 6 (Continued) 146 Experiment 4a utilized the same solutions and concentrations as experiment 4 with the exception of a higher concentration of pyrite, 0.9 g/1. The results of experiment 4a (Figure 11) show a faster rate of proton evolution than experiment 4 This is probably due to a higher concentration of pyrite used in experiment 4a. Experiment 4a A558nm 0 .71 o 6 -PO-o co-----o-o---o 0 5 0 3 0 4 0 2 ". .. 0 1 Figure 11 Experiment 0 1 0 20 30 40 50 60 70 Time (hrs) Initial hydrogen ion evolution rate 4a Experiment 5 80 Experiment 5 utilized oxygen saturated, 0 7 M NaCl buffered with borate buffer/boric acid (1.0 x 10-4 M total boron 2 x 10-6M phenol red) m 10 em pathlength glass spectrophotometer cells. Two cells contained 102-53 size fraction, acid washed pyrite (U. S.G S.

PAGE 168

APPENDIX 6 (Continued) 1 4 7 sample #79SK002) : 1a = 0.35 g/1, and 1b = 0 .51 g/1 Two other cells contained 53-20 J.lm size fraction: 2a = 0.16 g/1., and 2b = 0.28 g/1. A fifth cell, containing no mineral, served as a blank. The cells were incubated at 25C for ca 70 hours and absorbances at 558 nm measured periodically. The results are shown in Figure 12. As expected, the higher concentrations of pyrite produce more protons, and the smaller size fraction of mineral (with a larger surface area) produces more hydrogen ions than an equivalent amount of the larger size fraction If normalized for variations in pyrite concentrations, there would be a greater difference apparent between the two sizes. Experiment 5 o. 9 c---------------- Control0 8 T1a 0A558nm 0.7 T1b T2a 0 0.6 T2b -.t.0.5 Figure 12 Experiment 0 1 0 20 30 40 Time (hrs) 50 60 Initial hydrogen ion evolution rate 5 70 80

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APPENDIX 6 (Continued) 148 Experiment 5a Experiment 5a employed the same solutions and procedures a s experiment 5. The pyrite concentrations were: T1 a = 0.51 g/1 and T1 b = 0.91 g/1, for the 102-53 J.lm size fraction; and T2a = 0.61 g/1 and T2b = 0.50 g/1, for the 53 20 J.lm size fraction. The result s are graphed in Figure 13 and show the same trends as those of experiment 5. Experiment 5a 1 2 --------1 0.8 o, A558nm 0 6 o o-o C ontro l -T 1 a T1b ... __ ... T 2a 0 4 T2b 0 2 o-o 0 5 10 1 5 20 2 5 30 35 40 4 5 5 0 55 Figure 13 Experiment Tim e (hrs) Initial hydrogen ion evolution rate Sa -0--D-

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149 APPENDIX 7 Results of hydrogen ion evolution experiments Blank Results The stability of absorbance measurements in the hydrogen ion evolution experiments was examined by inclusion of blank solutions (no mineral) in the exp er iments For example, changes in absorbance could occur with temperature fluctuations acid leaching from the cell carbon dioxide invasion or other contamination problems. Figures 14 and 15 present the change m total alkalinity with time calculated for all of the blanks, for marcasite and pyrite, respectively. The average value of the change in total alkalinity with time (dTA/dt) for the blank solutions of all studies is -2 5 6 1 x 10 8 m/hr for marcasite and -5.4 7 1 x 10-8 m/hr for pyrite. (Some slopes are positive; absorbance increases slightly.) The magnitude of dTA/dt (not normalized for mineral concentration) for the test samples is always higher than the blank values. The mean value for pyrite is -4.9 x 10-7 m/hr with a range of -1.3 x 10-7 to -1.5 x 10 6 m/hr, and for marcasite, the mean is -4.5 x 10-7 m/hr with a range of -3.7 x 10-8 to 1.4 x 10 -6 m/hr. Contribution by the blank solution to absorbance change is small

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APPENDIX 7 (Continued) Study 4 4 4 4 3 3 3 2 2 2 2 2 1 1 1 1 -4E-07 Solution Blanks-Marcasite -3E-07 -2E-07 -1 E-07 aT A/h r 0 Figure 14 Marcasite blank results for hydrogen ion evolution experiments 4 4 4 3 3 3 2 Study 2 2 2 1 1 1 1 1 Solution Blanks-Pyrite 1111! r. .r150 0.0000001 -4.00E-07 -3.00E-07 -2.00E-07 -1.00E-07 O.OOE+OO 1.00E-07 aT A/h r Figure 15 Pyrite blank results for hydrogen ion evolution experiments

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APPENDIX 7 (Continued) 151 Hydrogen ion evolution results Tables 61 88 report data from the spectrophotometric monitoring of pH changes as marcasite and pyrite oxidize Table 90 lists values for parameters used in the total alkalinity calculations. Tables 91 97 summarize the data in Tables 62 89. An explanation of symbols and abbreviations can be found in the List of Symbols. The parameter T A t, which is listed in Tables 62 89, is calculated by linear regression analysis of time and total alkalinity, and is the rate of hydrogen ion production normalized for mineral surface area The slope designated "Omit 1st" omits the first absorbance and the slope designated "All data"includes all data points. Figure 16, a graphical representation of change in total alkalinity with time, is typical of the hydrogen ion experiments Omitted samples All tests with problems that may effect the results have been indicated in the following tables and omitted from the calculations m the summary tables. Common problems during the experiments which were considered to be an appropriate reason for omission were: loss of solution, loss of mineral sample, or contamination of cuvets. An entire experiment has been omitted because the temperature of the cuvet housing of the spectrophotometer was not 25C. Outliers

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APPENDIX 7 (Continued) Several data points were extreme outliers, greater than 3 standard deviations from the mean Mean values are calculated 152 including and excluding these outliers. However, the values listed tn Tables 7 and 8 do not include the outliers. Marcasite Seawater 11-3-86 9.5000E-05 9 .0000E-05 -- B lk 8.5000E-05 R1 .Q-S OOOOE-05 TA R2 -7.5000E-05 R'l -<>-?.OOOOE-05 --6 .5000E-05 S.OOOOE-05 0 2 3 4 5 6 7 8 9 Tim e (h r s) Figure 16 Oxidation Change in total alkalinity with time-Marcasite in seawater (11-3-86)

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APPENDIX 7 (Continued) 153 Table 62 Marcasite hydrogen ion evolution in 0.7 M NaCl (10-4-86) Cuvet Time Total All data Om it 1st Reading A558NM (hrs) Alkalinity 6TA*/6t 6TA*/6t Prob le m TOblk 1 0 .8510 7.941 1 .22 4 .043E-05 0.000 0.000 2 0 .8523 7 .943 1 .37 4 .064E-05 3 0.8525 7.944 1.52 4 .067E-05 4 0 .8536 7.946 2 .20 4 .085E-05 5 0 .8526 7.944 4 .58 4 .069E-05 6 0 .8525 7.944 5 .80 4 .067E-05 T1 1 0 7884 7.826 0 .75 3 .194E-05 -1.90E-05 -1.44E-05 2 0 7741 7 801 2 .67 3.035E-05 3 0. 7661 7 .788 4 .17 2 .950E-05 4 0 7638 7 .784 4 .92 2 .927E-05 T2 1 0 7789 7.809 0 .80 3 .087E-05 4. 73E-05 -3.23E-05 outlier 2 0 7355 7.737 3.17 2.653E-05 3 0 7182 7.709 4 .28 2.502E-05 4 0 7130 7. 701 5 .08 2 .459E-05 T4 1 0 8191 7.881 0.88 3.576E-05 -8. 79E-06 6 .12E-06 2 0 .8124 7 .869 3 .33 3.487E-05 3 0 .8103 7.865 4 .67 3.460E-05 4 0 .8093 7.863 5.28 3.447E-05 T5 1 0 .8149 7 .873 1 .03 3 .520E-05 -5 .20E-06 -3 73E-06 Lost 2 0 .8059 7.857 3 .55 3.404E-05 Sample 3 0 .8022 7.850 4 .75 3.358E-05 4 0 .8017 7 .849 5.47 3.352E-05

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APPENDIX 7 (Continued) 154 Table 63 Marcasite hydrogen ion evolution in 0.7 M NaCl (10-5-86) Cuvet Time Total All data Omit 1st Reading A558nm p-t (hrs) Alkalinity Problem R7BLK 1 0.8391 7 .918 0 .67 3 481 E-05 0 .000 0 .000 2 0.8405 7 921 4 .02 3 .499E-05 3 0 .8397 7 .919 4.95 3 .489E-05 4 0 .8399 7.920 6.50 3.491 E-05 R3 1 0. 7843 7.819 0.73 2.846E-05 Missing 2 0. 7685 7 .792 3 .10 2 .692E-05 weight 3 0. 7659 7 .787 4.10 2.668E-05 4 0. 7626 7 .782 5.68 2 .638E-05 R4 1 0.8218 7 .886 0.93 3.261 E-05 -7. 76E-06 -5 .43E-06 2 0 .8136 7 871 3.25 3.164E-05 3 0 .8120 7.868 4 .22 3 .145E-05 4 0 .8087 7.862 5 .83 3 1 07E-05 R5 1 0.8039 7.853 1 1 0 3 .053E-05 -5 .41 E-06 -4.05E-06 2 0. 7970 7 841 3.47 2.978E-05 3 0 7951 7.838 4.42 2 .958E-05 4 0. 7924 7.833 6 .00 2 .929E-05 R6 1 0 .8211 7.885 1.35 3 .253E-05 -6.96E-06 -6.35E-06 2 0 .8147 7 .873 3 .70 3 .176E-05 3 0 .8120 7 .868 4.70 3 .145E-05 4 0.8087 7 .862 6.18 3 1 07E-05

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APPENDIX 7 (Continued) 155 Table 64 Marcasite hydrogen ion evolution in 0.7 M NaCI (10-8-86) Cuvet Time Total All data Omit 1 s t Read i ng A558nm (hrs) Alkalin i ty 6TA"/6t 6TA./6t Problem TOBLK 1 0 7176 7 .846 2 .00 2 .992E-05 0 .000 0 .000 2 0 7170 7 .844 3 .08 2.984E-05 3 0 7171 7 .845 4 .92 2 .986E-05 4 0 7143 7 .839 6 .98 2 .952E-05 T4 1 0 .6735 7.762 0 .63 2 .516E-05 -7.15E-06 -5.40E-06 2 0 .6653 7 .747 2 .18 2 .439E-05 3 0 .6582 7.734 5 .07 2 .374E-05 4 0 .6566 7 731 5.95 2 .360E-05 T5 1 0 .6765 7 .767 0 .73 2 .545E-05 -7.43E-06 -5.58E-06 2 0 .6684 7 .752 2 .33 2 .468E-05 3 0 .6615 7 .740 5 .20 2 .404E-05 4 0 .6600 7 .737 6 .13 2 .390E-05 T6 1 0 .6822 7 .778 0 .90 2 .602E-05 6 .49E-06 -5.23E-06 2 0.6776 7 .769 2.55 2 .556E-05 3 0 .6732 7 761 5.37 2 .513E-05 4 0.6721 7 .759 6.33 2 .503E-05 T7 1 0 .6675 7 751 1 .63 2.459E-05 -7.01 E-06 -6.34E-06 2 0 .6618 7 .740 2 .68 2 .406E-05 3 0 .6517 7 .722 5 .68 2 .317E-05 4 0 .6488 7 .717 6 .50 2 .292E-05

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APPENDIX 7 (Continued) 156 Table 65 Marcasite hydrogen ion evolution in 0. 7 M NaCI (10-10-86) Cuvet Time Total All data Omit 1st Reading A558nm (hrs) Alkalinity 4TA/at AT A./At Problem R7BLK 1 0.9062 7.900 0.72 3.367E-05 0.000 0.000 2 0.9064 7.900 2.43 3.369E-05 3 0.9063 7.900 4.83 3.368E-05 4 0.9065 7.900 6.83 3.371 E-05 5 0.9063 7.900 8.27 3.368E-05 R3 1 0.8342 7.783 0.92 2.658E-05 -2.53E-05 -1.66E-05 Con2 0.8042 7.738 2.87 2.420E-05 taminant 3 0.7871 7.712 4.93 2.296E-05 4 0.7883 7. 711 5.45 2.291 E-05 5 0.7768 7.697 7.02 2.225E-05 R4 1 0.8863 7.866 1.32 3.148E-05 -8.30E-06 -6.59E-06 2 0.8799 7.856 2.88 3.081 E-05 3 0.8737 7.846 5.65 3 019E-OS 4 0.8714 7.842 7.25 2.998E-05 R5 1 0.8602 7.824 0.72 2.888E-05 -1.02E-05 -8.18E-o6 2 0.8511 7.809 3 .10 2.805E-05 3 0.8446 7.799 5.86 2.747E-05 4 0.8414 7.794 7.43 2.719E-05 R6 1 0.8810 7.857 1.67 3.092E-05 -5.67E-06 -4.02E-06 2 0.8763 7.850 3.35 3.045E-05 3 0.8729 7.844 8.07 3.011 E-05 4 0.8718 7.842 7.67 3.000E-05

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APPENDIX 7 (Continued) 1 57 Table 66 Marcasite hydrogen ion evolution in seawater '(10-31-86) Cuvet Total Time All data Om i t 1st Reading A558nm Alkalinity (hrs) 6TA*/6t 6TA*/6t Problem TO Blank 1 0 .4593 7.363 3 .525E-05 0 .68 0 .000 0 .000 2 0 .4592 7.363 3 .524E-05 0.95 3 0 .4592 7.363 3 .524E-05 2.78 4 0 .4588 7.363 3.519E-05 3.53 5 0.4591 7.363 3 .523E-05 5.75 6 0 .4585 7.362 3 .515E-05 7 .67 T4 1 0 .4420 7.335 3.31 OE-05 1 .55 -1.22E-05 -9.65E-06 2 0 .4337 7 321 3 .21 OE-05 4 .05 3 0 .4256 7.307 3 .115E05 7.47 4 0 .4261 7.308 3 121 E-05 8 .37 T5 1 0.4419 7 .335 3 .308E-05 1 .90 -1.08E-05 -5 .05E-06 2 0.4337 7 321 3 .21 OE-05 6 .25 3 0.4322 7 .319 3 .192E-05 7.25 4 0.4319 7.318 3 .189E-05 8 .53 T6 1 0.4220 7 301 3 .073E-05 2.10 -1.41E-05 9 .11 E -06 2 0 .4072 7.276 2 .906E-05 4.80 3 0.4022 7.268 2.852E-05 7.00 4 0 .3980 7 .260 2.806E-05 8.70 T7 1 0.4278 7 311 3 .140E-05 2.30 -9.14E-06 -6.27E0 6 2 0.4211 7 .300 3.063E-05 5.03 3 0.4185 7.295 3.033E-05 7 .20 4 0.4166 7.292 3 .012E-05 8 .90

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APPENDIX 7 (Continued) 158 Table 67 Marcasite hydrogen ion evolution in seawater .(11-3-86) Cuvet Total Time All data Om i t 1 st Prob lem Read ing A558nm Alkalinity (hrs} R7 BLANK1 0 7373 7.8268 9 .475E-05 0 .60 0 .000 0 .000 2 0 7343 7.8212 9 .368E-05 2.40 3 0.7331 7.8190 9 .325E-05 5 .70 4 0 7324 7.8177 9 .300E-05 8 .00 R1 1 0 .6988 7 .7573 8 .209E-05 0 .60 -8 .18E-05 -4 .35E-05 weight 2 0 .6798 7. 7242 7 661 E-05 2.48 problem 3 0 .6715 7 .7099 7 .436E-05 5 .75 4 0 .6683 7. 7044 7 351 E-05 8.12 R2 1 0 7061 7. 7702 8 .432E-05 0 .74 -7.67E-05 -4 .08E-05 2 0 .6564 7 .6843 7.046E-05 2.63 3 0 .6328 7 .6448 6 .482E-05 5 .88 4 0 .6229 7 .6285 6 261 E-05 8 .29 R3 1 0 .6910 7 .7436 7 .979E-05 0 .87 -4 .68E-05 2 .92E-05 2 0 .6743 7 714 7 7 .511E-05 2 .73 3 0 .6649 7 .6987 7.263E-05 5 .98 4 0.6605 7 .6912 7 .150E-05 8 .47 R6 1 0. 7331 7 .8190 9.325E-05 1 .03 -3 .99E-05 -2.46E-05 2 0. 7222 7 7991 8.95 1 E -05 2.83 3 0 7161 7 7881 8 749E-05 6 .13 4 0 7135 7 .7834 8 .665 E -05 8 .60

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APPENDIX 7 (Continued) 159 Table 68 Marcasite hydrogen ion evolution in seawater (11-4-86) Cuvet Total Time A ll data Omit 1st Reading A558nm p-1 Alkalinity (hrs) .1TAu.t .1TA./.1t Problem RO BLANK 1 0 71 08 7 781 8.612E-05 0 .57 0 .000 0 .000 2 0 .7096 7 .779 8 .574E-05 3 .03 3 0 7083 7 .777 8 .533E-05 6 .03 4 0 .7087 7 .777 8.545E-05 8 .58 T1 1 0 .6709 7 711 7.446E-05 0.63 -2.81 E -05 -1.51 E-05 2 0.6533 7 681 6 .992E-05 3.30 3 0 .6477 7 .672 6 .855E-05 6 .12 4 0 .6436 7 .665 6. 756E-05 8 .65 T2 1 0.6613 7.695 7.195E-05 0 .79 -1.23E-04 -7.09E-05 2 0 .6234 7 631 6 .292E-05 3 .59 3 0 .6075 7.605 5 .951 E 05 6.42 4 0.5988 7.591 5 .773E-05 8 .86 T4 1 0 .6798 7 .727 7 .689E-05 0 .92 -2 .23E-05 -1.61E-05 2 0 .6744 7 .717 7 .540E-05 3 .77 3 0 .6725 7 714 7 .489E-05 6.40 4 0 .6699 7. 710 7 .419E-05 9 .00 T5 1 0.6833 7.733 7 787E-05 1.03 1.91 E-05 -1.35E-05 2 0.6767 7 721 7.603E-05 3 .90 3 0.6732 7 .715 7 .508E-05 6 .53 4 0.6711 7 .712 7 .452E-05 9 .1 3

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APPENDIX 7 (Continued) 1 6 0 Table 69 Marcasite hydrogen ion evolution in seawater (11-13-86) Cuvet Total Time All data Omit 1st Problem Reading A558nm p-1 Alkalinity (hrs) TA./.1t .1TA./.1t T7 BLANK1 0.5421 7.499 4.739E-05 1.67 0 .000 0.000 2 0 .5403 7 .496 4.709E-05 5 .37 3 0.5394 7.495 4.695E-05 17.60 AO BLANK1 0 .5684 7 .542 5 .194E-05 2 .02 2 0.5686 7 .542 5.197E-05 4 .50 3 0 5681 7.541 5 .188E-05 5 .65 4 0.5682 7.541 5.190E-05 16.47 A3 1 0 .5160 7.457 4 .325E-05 0 .75 -1.58E-05 6 .95E-06 2 0 .4896 7 .414 3.940E-05 4 .55 3 0 .4785 7 .396 3. 787E-05 16.65 R4 1 0 .5466 7 .506 4.814E-05 0 .92 -7 .16E-06 4. 73E-06 2 0 .5399 7.496 4. 703E05 4 .65 3 0 .5342 7.486 4.61 OE-05 16 .88 AS 1 0.5417 7.498 4 733E-05 1 .00 -1.42E-05 -8 .33E-06 2 0.5277 7.476 4.507E-05 4.78 3 0.5182 7 461 4 .359E-05 17 .03 T2 1 0 .4948 7.423 4 .014E-05 1.1 0 -5. 78E-05 -3 .27E-05 2 0 .4388 7 331 3.279E-05 4.92 3 0 .4002 7 .265 2 .837E-05 17 .20 T4 1 0.5227 7.468 4.428E-05 1.25 -8.09E-06 -5.41 E-06 2 0.5165 7 .458 4 .333E-05 5.08 3 0.5111 7.449 4.252E-05 17.37

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APPENDIX 7 (Continued) 1 6 1 Table 70 Marcasite hydrogen ion evolution in 7% 02 (12-9-8 6) Cuvet Total Time All data Omi t 1st Problem Reading A558nm p-i Alkalinity (hrs) RO BLANK1 0 7062 7 .769 8.423E-05 1 .37 0 .000 0.000 2 0. 71 02 7.776 8.548E-05 4 .27 3 0 .7087 7 .774 8 501 E -05 18.93 4 0. 7080 7 .772 8 .479E-05 24.15 T7 1 0 7113 7.778 8.583E-05 1.43 -1.20E-05 -1.06E-05 2 0 .7007 7 .759 8.255E-05 4 .32 3 0.6728 7 711 7 .462E-05 21.72 T9 1 0. 7330 7 .818 9 .308E-05 1.47 -7.87E-06 -7. 76E-06 2 0 7301 7 .812 9 .207E-05 4.33 3 0 7143 7 .784 8 .679E-05 21.38 T2 1 0 .6733 7 712 7 .475E-05 1. 72 -1.81 E -05 -1.44E-05 2 0 .6594 7 .688 7 .113E-05 4 .57 3 0 .6354 7 .648 6.535E05 20.82 T8 1 0. 7009 7 .760 8 261 E-05 1 .90 -6 .29E-06 -5.97E-06 2 0 .6962 7 .752 8 .120E-05 4 .62 3 0 .6770 7.718 7 .575E-05 21.97 4 0 6741 7 .713 7 .497E-05 25.53 T5 1 0 .6972 7 .753 8 .150E-05 2 .38 8 .92E-06 -7.85E-06 2 0 .6923 7 .745 8 .006E-05 4 .77 3 0.6793 7.722 7 .638E-05 21 .18 R4 1 0 .7114 7 .778 8 .586E-05 2 .42 -1.78E-05 -1.18E-05 2 0 .6827 7.728 7 .732E-05 19.27 3 0 .6787 7. 721 7 .622E-05 22.27 4 0 6771 7 .718 7 .578E-05 24.22 R7 1 0 7020 7 .762 8.294E-05 2.67 -1.009E-05 -1.028E-05 2 0.6658 7 .699 7 .277E-05 19.88 3 0 6621 7 .693 7.182E-05 22.48 4 0 .6538 7.679 6 .973E-05 25.00 R3 1 0 .6817 7 .726 7 .704E-05 2.92 -1.115E-05 -5.818E-06 2 0 .6553 7 681 7 .01 OE-05 20.15 3 0 .6533 7 .678 6 .961 E-05 22.80 4 0 .6518 7 .675 6 .924E-05 24.60 R1 1 0 .6654 7 .698 7 .267E-05 3 .17 -8 .624E-06 -4.472E-06 2 0.6417 7.659 6.681 E-05 20.32 3 0.6402 7 .656 6.646E-05 23.02 4 0 .6385 7 .653 6 .606E-05 24.87 R9 1 0 .6986 7 .756 8 .192E-05 3 .57 -9.149E-06 8 .014E-06 2 0.6832 7.729 7 .746E-05 20.43 3 0 .6813 7 .726 7 .693E-05 23.15 4 0 .6799 7 .723 7 .655E-05 24.38

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APPENDIX 7 (Continued) 162 Table 71 13-86) Marcasite hydrogen ion evolution in 7% 02 (12-Cuvet Total Time All data Omit 1s t Problem Reading A558nm J:i-1 Alkalinity (hrs) 6TA*/6t 6TA*/6t ROBLK 1 0 .8848 8 .154 1 .796E-04 0 .72 0.00 0 .00 2 0 .8839 8 .152 1 .788E-04 19 .42 3 0 8831 8 .150 1 .781E-04 25.08 R1 1 0.8464 8.056 1 .495E-04 0.93 -8 .07E-06 -6.28E-06 2 0 .8423 8 .047 1 .467E-04 3 .37 3 0 .8358 8 .032 1 .425E-04 21.30 R3 1 0 .8502 8 .066 1 .521 E-04 1 .03 -9 .31 E-06 1 .01E-05 2 0.8502 8 .066 1.521 E-04 3.43 3 0 .8438 8 .050 1.477E-04 20.93 T4 1 0 .8659 8 .104 1 .637E-04 1 .03 -8 .44E-06 -8.30E-06 2 0 .8649 8 .102 1 .629E-04 3 .47 3 0 .8589 8 .087 1.584E-04 21.00 T2 1 0 .8597 8.089 1.590E-04 1.18 -1.67E-05 -1.40E-05 2 0 .8532 8 .073 1 .542E-04 3 .62 3 0 .8389 8 .039 1 .445E-04 21.38 R7 1 0.8721 8.120 1.687E-04 1 .47 -1.06E-05 -8.92E-06 2 0.8669 8 .107 1.645E-04 3 .75 3 0 .8550 8 .077 1 .555E-04 21.60 T9 1 0.8754 8.129 1.714E-04 1 .82 -1.30E-05 -7.33E-06 2 0 8621 8.095 1.608E-04 19.42 3 0.8618 8.094 1 .606E-04 21.82 4 0.8598 8 .089 1 .590E-04 25.27 T8 1 0 .8620 8 .095 1 .607E-04 2 .02 -1.20E-05 4 .98E-06 2 0 .8473 8 .059 1 501 E -04 19.80 3 0.8468 8 .057 1 .497E-04 21.95 4 0.8455 8 .054 1.489E04 25.45 T7 1 0 .8743 8 .126 1 705E-04 2 .97 -1.15E-05 9 1 2E-06 2 0.8656 8.104 1.635E-04 20.57 3 0.8638 8 .099 1 .621 E -04 25.13 R9 1 0.8677 8 .109 1 .651 E 04 3.15 -8 .15E-06 -3. 6 6E-06 2 0 .8576 8 .084 1 .574E-04 20.73 3 0.8564 8 081 1 .565E04 2 5 .67

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APPENDIX 7 (Continued) 163 Table 72 17-86) Marcasite hydrogen ion evolution in 7% 02 ( 12-Cuvet Total Time All data Omit 1st Problem Reading A558nm p-l Alkalinity (hrs) 6TA*/6t 6TA*/6t R m RO BLANK1 0 .8935 8.180 1 .874E-04 3.82 0 .000 0.000 dropped 2 0 .8917 8 .175 1 .857E-04 18 .85 due to 3 0 .8928 8.178 1 .868E-04 21.20 temp. 4 0 .8927 8 .178 1 .867E-04 24.20 control 5 0.8922 8.177 1.862E-04 26.33 problems R7 1 0 .8843 8 .155 1. 789E-04 3.73 -1.23E-05 -1 .32E-05 2 0 .8848 8 .156 1 .793E-04 4 .87 3 0 .8776 8 .137 1 .730E-04 19.12 4 0.8768 8 .135 1 .723E-04 22.43 R9 1 0 .8847 8 .156 1 .792E-04 3 .78 -9.85E-06 -4.54E-06 2 0 .8734 8 .126 1 .695E-04 19.30 3 0 .8722 8 .122 1 .685E-04 23.00 T9 1 0 .8749 8 .130 1 .707E-04 4.00 -1.418E-05 -8.996E-06 2 0.8659 8 .106 1 .635E-04 19 .68 3 0.8648 8 .104 1.626E-04 22.72 T8 1 0 .8888 8 .167 1.830E-04 4 .11 -2 .12E-05 -1 .57E-05 2 0 .8768 8 .135 1.723E-04 19.79 3 0.8750 8 .130 1.708E-04 22.91 R4 1 0 .8737 8 .126 1 .697E-04 4 .12 7 0 1 E-06 2.46E-05 2 0 .8643 8.102 1 .622E-04 20.02 3 0.8684 8.113 1 .654E-04 22.98 R3 1 0 .8728 8 .124 1.690E-04 4 .14 -8.05E-06 -1.75E-06 2 0 .8670 8 .109 1.643E-04 20.13 3 0.8666 8 .108 1.640E-04 26.18 R1 1 0.8665 8 .108 1.639E-04 4 .38 -1.08E-05 -4.28E-06 2 0.8578 8 .086 1 .573E-04 20.28 3 0.8566 8 .083 1 .565E-04 26.58 T7 1 0 .8724 8 .123 1 .687E-04 4 .55 -5 73E-06 -8.84E-07 2 0 8681 8.112 1 .652E-04 20.62 3 0 .8679 8. 111 1 651 E-04 26.45 T5 1 0 .8764 8 .133 1 .720E-04 4 .71 -5. 70E-06 -3.42E-06 2 0 .8707 8 .119 1.673E-04 20.78 3 0 .8695 8 .116 1 .663E-04 26.88

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APPENDIX 7 (Continued) 164 Table 73 Marcasite hydrogen ion evolution at low temperature (12-22-86) Cuvet To t al Time All data Omi t 1st Problem Reading_ A558nm Alkalinity (hrs) &TA./&t &TA./&t RO 1 0 .6399 7 .913 6 .817E-05 1 .08 0.000 0 .000 2 0 .6397 7 .913 6 .812E-05 3 .47 3 0 .6393 7 .912 6 .803E-05 18.58 4 0.6400 7 .913 6 .819E-05 21 .82 R7 1 0 .6398 7 .913 6 .815E-05 1.38 -9.37E-07 -6.71 E-07 2 0 .6362 7 .907 6 .734E-05 16.92 3 0.6351 7 .905 6 .709E-05 24.17 R3 1 0 .6206 7.883 6 .396E-05 1 .84 -2.57E-06 -2.24E-06 2 0 .6155 7 .875 6 .289E-05 17.19 3 0 .6140 7 .872 6 .258E-05 22.46 R4 1 0 .6262 7 .891 6 .515E-05 2 .02 -3.02E-07 1 .97E-07 2 0 .6255 7 .890 6 .500E-05 17.48 3 0 .6256 7 .890 6 .502E-05 22.00 R9 1 0 .6456 7.922 6 .947E-05 2.23 -9.96E-07 4.41 E-07 2 0.6429 7 .918 6 .885E-05 17.65 3 0.6432 7 .918 6.892E-05 22.85 AS 1 0.6296 7.897 6.589E-05 2.53 -6.04E-07 6 81 E-07 2 0 .6281 7 .894 6 .556E-05 17.93 3 0 .6275 7 .893 6.543E-05 23. 21 T4 1 0.6291 7.896 6.578E-05 2.68 -1.03E-06 -1.40E-06 2 0 .6262 7 891 6 .515E-05 18.07 3 0 .6246 7.889 6 481 E-05 23.72 T9 1 0 .6485 7 .926 7 .014E-05 2 .87 -7 .40E-07 3 .55E-07 2 0 .6449 7.921 6 931 E-05 18.23 3 0 .6443 7.920 6 .917E-05 24.35 T8 1 0 .6470 7.924 6 .979E-05 3.08 -5.51 E-06 2 .13E-06 2 0 .6370 7.908 6 .752E-05 18.67 3 0 .6362 7.907 6.734E-05 22.12 T5 1 0 .6331 7.902 6 .665E-05 3 .26 -5.83E-07 -1.24E-06 2 0 .6321 7.901 6 .643E-05 18.91 3 0 .6315 7 .900 6.630E-05 22.56

PAGE 186

APPENDIX 7 (Continued) 165 Table 74 Marcasite hydrogen ion evolution at low temperature (1-3-87) Cuvet Total Time All data Om it 1st Reading A558nm Alkalinity (hrs) ATA*/td ATA*/At Problem RO BLANK1 0.7397 8.095 9 .779E-05 1.27 0 .000 0 .000 2 0 7437 8.1 02 9 .918E-05 3.57 3 0. 7434 8.102 9 .908E-05 21.90 4 0.7446 8 .104 9 .950E-05 22.82 5 0.7446 8 .104 9.950E-05 26.60 6 0 .7438 8 .103 9 .922E-05 28.67 7 0 .7435 8.102 9 911 E-05 41.63 R1 1 0 7182 8 .059 9 071 E-05 1.49 -9.37E-07 -9.53E-07 Temp 2 0. 7189 8.060 9.093E-05 4 .24 problem 3 0. 7174 8 .057 9 .046E-05 19.86 4 0 7165 8.056 9 .018E-05 26.74 5 0 7140 8.051 8.940E-05 46.77 6 0. 7119 8.048 8.876E-05 67.71 R9 1 0. 7059 8.038 8.694E-05 1.70 -1.17E-06 -1.07E-06 Temp 2 0. 7064 8.039 8.709E-05 4.43 problem 3 0. 7042 8.035 8 .643E-05 20.10 4 0. 7024 8 .032 8.590E05 26.97 5 0 7013 8 .030 8 558E-05 46.98 6 0.6973 8 .023 8 .442E05 68.32 R4 1 0. 7183 8 .059 9 .074E05 1.92 -1.63E-06 -1.83E-06 Con t am 2 0. 7301 8.079 9.455E-05 20.37 -ina ted 3 0.7294 8.078 9.432E-05 27.23 4 0.7267 8 .073 9.343E0 5 47.15 5 0 .7233 8 .067 9 .233E-05 68.15 R5 1 0 7380 8.092 9.721 E-05 2 .29 -2.07E-06 1.74E-06 2 0. 7347 8.087 9 .609E05 20.74 3 0. 7335 8.085 9 .568E-05 27.48 4 0. 7317 8 .082 9 .508E-05 42.68 R3 1 0.7096 8.044 8.806E-05 2.58 -1.88E-06 -1.77E-06 2 0 .7077 8 041 8 .748E05 20.93 3 0.7068 8.039 8 .721E-05 27.73 4 0.7056 8 .037 8 .685E-05 42.00 T5 1 0 .7220 8 .065 9 .192E-05 2.98 -2.20E-06 -2.92E-06 2 0.7203 8 .062 9 .138E-05 21.27 3 0 7187 8 .059 9 .087E05 28.13 4 0 7159 8.055 8 .999E-05 42.40

PAGE 187

APPENDIX 7 (Continued) 166 Table 74 continued Cuvet Total Time All data Omit 1st Reading A558nm Alkalinity (h rs) &TAt&t &TA./&t Problem T4 1 0. 7217 8.064 9 .182E-05 3 .25 -8.44E-07 -1.14E-06 weight 2 0 7204 8.062 9 .141E-05 21.57 problem 3 0 7191 8 .060 9 1 OOE-05 28.43 4 0. 7170 8.056 9 .034E-05 47 48 5 0 7159 8 .055 8 .999E-05 68.67 T8 1 0 .7255 8 071 9 .304E-05 3.78 -1.94E-06 1 .12E-06 weight 2 0 7227 8 .066 9 .214E-05 22.15 problem 3 0 .7224 8.066 9 .204E-05 28.90 4 0 .7215 8 .064 9 .176E-05 42.20 T9 1 0 .7226 8 .066 9.211 E-05 3 .98 5 77E-07 -1.07E-06 2 0 7228 8 .066 9 2 17E-05 22.47 3 0 7215 8 .064 9 .176E-05 29.15 4 0 .7210 8 .063 9 .160E-05 42.50

PAGE 188

APPENDIX 7 (Continued) 167 Table 75 Marcasite hydrogen ion evolution at low temperature (1-31-87) Cuvet Total Time All data Omi t 1st Problem j Read ing A558nm li-\ 1>.\\<.a\ini\y b.\ f... lb.\ b.\fi...l b.\ \ \ R1 1 0 .8290 8 .255 1 .349E-04 7.43 0 .000 0.000 2 0 .8278 8 .253 1 .342E-04 24.03 3 0 .8268 8.251 1 .337E-04 45.35 4 0 .8264 8.250 1 .335E-04 53.57 T9 1 0.84 77 8 .294 1 .452E-04 9 .94 2 0 .8468 8 .292 1 .447E-04 26.69 3 0 .84 75 8 .293 1 451 E-04 48.03 4 0 .8481 8 .294 1 .455E-04 53. 91 R9 1 0 .8543 8 .308 1.491 E-04 7 .73 1.49E-06 1 .36E-06 2 0.8505 8 .300 1 .469E-04 24.36 3 0.8466 8 .291 1.446E-04 45.69 4 0.8449 8 .288 1.436E-04 55.89 R7 1 0 .8444 8 .287 1.433E-04 8 .05 -1.27E-06 1 .13E-06 2 0 .8394 8 .276 1 .405E-04 24.77 3 0 .8334 8 .264 1 .372E-04 46.07 4 0.8324 8 .262 1 .367E-04 56.23 AS 1 0 .8583 8 .316 1 .516E-04 8 .36 -4. 78E-06 -3. 79E-06 Con tam 2 0 .8479 8 .294 1 .453E-04 25. 11 ina ted 3 0 .8386 8 .275 1 .400E-04 46.36 4 0.8373 8 .272 1.393E-04 54.89 R4 1 0 .8406 8 .279 1.412E-04 8 .72 -7.78E-07 -2.41 E-07 weight 2 0.8376 8 .273 1 .395E-04 25.40 p roblem 3 0.8372 8 .272 1.393E-04 46.75 4 0 .8369 8 .271 1.391 E-04 54.55 TS 1 0 .8442 8 .286 1 .432E-04 8 .97 -2.13E-06 -1.90E0 6 2 0 .8407 8 .279 1 .412E-04 25.65 3 0 .8375 8 .272 1 .394E-04 47.00 4 0 .8362 8 .270 1 .387E-04 54.15 T4 1 0 .8319 8 .261 1 .364E-04 9 .28 -8.98E-06 1. 2 1 E-05 outlier 2 0 .8287 8 .254 1 .347E-04 26.03 3 0 .7884 8 .176 1 .156E-04 47.00 4 0 .7867 8 .173 1 .149E-04 55.17 T2 1 0 .8244 8 .246 1 .325E-04 9 .62 -3. 1 OE-06 -2.36E-06 2 0 .8143 8 .226 1 .274E-04 26.35 3 0 .8073 8 .212 1 241 E-04 47.63 4 0.8049 8 .208 1.230E-04 55.53

PAGE 189

APPENDIX 7 (Continued) 168 Table 76 13-86) Pyrite hydrogen ion evolution in 0.7 M NaCl (10Cuve t T i me Total A ll dat a Omit 1st Reading A558nm (hrs) Alkalinity t.TA*/t.t t.TA*It.t Prob l em TO 1 0 .7544 7 .795 1.07 2 711 E-05 0 .000 0 .000 2 0 7547 7 .796 3 .33 2. 714E-05 3 0. 7545 7 .796 5 .18 2 712E-05 4 0 7548 7.796 7 .22 2. 715E-05 5 0 7543 7.795 8 .22 2 .71 OE-05 T4 1 0 6811 7.673 1.58 2 1 05E-05 -1.50E-05 -1.13E-05 2 0.6679 7.652 3 5 2 .013E-05 3 0 6601 7 .640 5 .35 1 .962E-05 4 0.6543 7.631 7 .28 1.924E-05 T5 1 0 7015 7.706 2.02 2.255E-05 -9. 72E-06 -8 .31 E -06 2 0 .6949 7 .696 3.75 2 .205E-05 3 0 .6903 7.688 5 52 2.171 E-05 4 0 .6856 7 681 7.5 2 .137E-05 T6 1 0 7036 7 710 2 .18 2 271 E -05 6 .91 E-06 -6 .13E-06 2 0 .6973 7.700 3 9 2.223E -05 3 0 .6919 7.691 5 .83 2.183E-05 4 0 .6873 7 .683 7.7 2 .149E-05 T7 1 0 .6974 7.700 2.35 2.224E-05 -1.06E-05 -8.73E-06 2 0 .6910 7.689 4.05 2.176E-05 3 0 6861 7.681 6 .08 2 .140E-05 4 0.6825 7.676 7 8 7 2 .115E0 5

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APPENDIX 7 (Continued) 169 Table 77 14-86) Pyrite hydrogen ion evolution in 0.7 M NaCI (10-Cuvet Time Total All data Om i t 1st Reading A558nm p-1 (hrs) Alkalinity 6TA*/6t .6TA*/.6t Problem R7 1 0.8635 7.997 0.72 4.072E-05 0 .000 0.000 2 0.8605 7 991 3 .43 4 .022E-05 3 0 .8595 7.989 5.00 4 .005E-05 4 0.8600 7.990 7.70 4.014E-05 5 0 .8599 7 .989 9 .05 4 .012E-05 R2 1 0.8185 7 .907 0 .80 3 401 E 05 -8.63E-05 -4.61 E-05 2 0 .7480 7.780 3 .48 2.625E-05 3 0. 7232 7 .738 5 .30 2.408E-05 4 0 7030 7 .705 7 .68 2 .248E-05 R3 1 0.8154 7 901 1 .15 3.361 E -05 -5.64E-05 -2. 76E-05 2 0. 7907 7.855 3 .82 3 .062E-05 3 0. 7839 7.843 5 .65 2 .987E-05 4 0 7793 7 .834 7 .90 2 .937E-05 R5 1 0.8563 7.982 1.48 3.953E-05 -1.03E-05 -7 .62E-06 2 0.8498 7 .969 3 .98 3 .849E-05 3 0.8470 7 .963 5.65 3 .805E-05 4 0 .8440 7 .957 8.05 3 .760E-05 R6 1 0 .8454 7 .960 1.68 3 781 E-05 -1.34E-05 -1.10E-05 2 0.8346 7.938 4 .20 3.621 E-05 3 0 .8285 7 .926 5 .77 3.536E-05 4 0 .8224 7 .914 8 .22 3.453E-05

PAGE 191

APPENDIX 7 (Continued) Table 78 Pyrite hydrogen ion evolution in 170 0.7 M NaCl (10-16-86) Cuvet Time Total A ll data Omit 1st Read i ng A558nm (hrs} Alkalinity tiTA*/t.t tiTA*/tit Problem TOBLK 1 0 .8529 7.976 0.77 3.906E-05 0 .00 0.00 2 0 .8529 7.976 4.20 3.906E-05 3 0 .8516 7.973 6 .42 3.885E-05 4 0.8514 7 .973 8 .20 3.882E-05 T4 1 0 .8048 7.882 0 .90 3.234E-05 -1.82E-05 -1.45E-05 2 0 7858 7.847 4.45 3 .013E-05 3 0 7770 7 831 6 .50 2 .917E-05 4 0. 7743 7.826 7 .40 2 .889E-05 T5 1 0.8210 7.912 1.13 3 .440E-05 -1.38E-05 -1.16E-05 2 0.8127 7 .897 4 .60 3.332E-05 3 0.8093 7.890 6 .65 3.289E-05 4 0.8072 7 .886 7 .57 3 .263E-05 T6 1 0.8165 7.904 1.73 3.381 E-05 -9.56E-06 -8.1 OE-06 2 0 .8119 7.895 4 .77 3.322E -05 3 0 .8098 7.891 6 .88 3 .296E-05 4 0.8085 7 .889 7 .72 3 .279E-05 T7 1 0.7834 7.843 2.40 2.986E-05 -1.02E-05 -8.23E-06 L os t 2 0 7773 7.832 4.87 2 .920E-05 sample 3 0 7739 7 .826 7.15 2 .884E-05 4 0.7723 7 .823 7.87 2.868E-05

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APPENDIX 7 (Continued) 171 Table 79 Pyrite hydrogen ion evolution in 0.7 M NaCI (10-17-86) Cuvet Time Total All data Omit 1st Reading A558nm (hrs) Alkalini ty .11TA*/.11t .11TA*/At Problem R7 1 0 .8960 7.901 0.60 3 .375E-05 0.000 0 .000 2 0 .8937 7 .897 3 .88 3 .348E-05 3 0 .8938 7 .897 6.00 3.349E-05 4 0 .8935 7 .896 7 .15 3.346E-05 R1 1 0.8301 7 .792 0 .68 2 709E -05 6 .22E-05 -2 .33E-05 2 0.7318 7 .645 4 .03 1 .997E-05 3 0.7097 7 .614 6 .90 1 .869E-05 4 0.7003 7 .600 8 .20 1 .817E-05 R2 1 0 .8138 7 .767 0 .95 2 .571 E 05 7 .78E-05 3 .84E-05 2 0. 7172 7 .624 4 .38 1 911 E -05 3 0 .6863 7 .580 6 .58 1 .742E-05 4 0.6760 7.566 7.97 1 690E -05 R3 1 0.8234 7 .782 1.53 2 651 E -05 -2.85E-05 -1.52E-05 2 0.7968 7.741 4 .58 2 .437E-05 3 0. 7909 7.732 6.42 2.393E-05 4 0 7861 7.725 7 .72 2.357E-05 R4 1 0 .8728 7 861 1 .83 3.117E-05 -7.49E-06 -5.99E-06 2 0 .8692 7.855 4.72 3.080E-05 3 0.8686 7.854 6 .50 3 .074E-05 4 0 .8668 7 851 7.52 3.055E-05

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APPENDIX 7 (Continued) 172 Table 80 28-86) Pyrite hydrogen ion evolution in seawater (10Cuvet Total Time All data Om i t 1st Reading A558nm Alkalinity (hrs) Problem TO 1 0 .6659 7.648 6 .530E-05 0 .70 0 .000 0 .000 2 0 .6658 7.647 6 .528E-05 3.55 3 0 .6652 7.647 6.515E-05 5.02 4 0 .6654 7 .647 6 .519E-05 7.42 T2 1 0.5899 7 .530 5 .073E-05 0.97 -4.53E-05 3 .77E-05 2 0 .5749 7.507 4 .827E-05 3.82 3 0 .5667 7.494 4 .697E-05 5 .07 4 0.5565 7.478 4 541 E-05 8.31 T4 1 0.6366 7 .602 5 .922E-05 1.15 2.11 E -05 -1.80E-05 2 0.6316 7 .594 5 .824E-05 4 .52 3 0.6299 7 591 5 .792E-05 5 .52 4 0 .6275 7 .588 5 .746E-o5 7 .88 T5 2 0 .6414 7 .609 6 .017E-05 4.07 -1.48E-05 -1.42E-05 3 0.6405 7 .608 5 .999E-05 5.15 4 0.6388 7 .605 5 .965E-05 7 .50 T7 2 0 .6230 7.581 5.661 E-05 4 .22 -3.12E-05 -2.85E-05 3 0.6187 7.574 5 .580E-05 5 .32 4 0 .6118 7 .563 5.454E-05 7.67

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APPENDIX 7 (Continued) 173 Table 81 29-86) Pyrite hydrogen ion evolution in seawater (10Cuvet Total Time All data Omit 1st Problem Reading A558nm p-1 Alkalinity (hrs) R7 1 0.8289 7 .929 1 .166E-04 0 .72 0 .000 0 .000 2 0 .8283 7 .928 1 .163E-04 0 .85 3 0 .8266 7 .925 1 .156E-04 2 .82 4 0.8262 7.924 1 .154E-04 4 .97 5 0.8262 7.924 1 .154E-04 7.83 R3 1 0. 7888 7 .854 1 .002E-04 1 .02 -7.54E-05 4 .50E-05 2 0 7812 7 .840 9. 746E-05 3.45 3 0 7785 7.835 9.650E-05 5 .02 4 0 7761 7 831 9 .566E-05 7 .97 R4 1 0 .8183 7 .909 1 .119E-04 1 .26 -3 .33E-05 -2 .51 E-05 2 0 .8152 7 .903 1 1 06E-04 3 .59 3 0 .8145 7 901 1 1 03E-04 5 .18 4 0.8124 7 .897 1 .094E-04 8 .14 R5 1 0 .8039 7 881 1 .060E-04 1 .50 -5.07E-05 -3.48E-05 2 0 .7987 7 .872 1 .040E-04 4.03 3 0 .7967 7 .868 1.032E-04 5.32 4 0. 7944 7 .864 1.023E-04 8.32 R6 1 0 .8052 7 .884 1 .065E-04 1.67 Missing 2 0.7996 7.873 1 .043E-04 4.47 weight 3 0 7974 7 .869 1 .035E-04 5.98 4 0 7949 7 .865 1.025E-04 8 .52

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APPENDIX 7 (Continued) 174 Table 82 8 6) Pyrite hydrogen ion evolution in seawater (11-8-Cuvet Total Time All data Omit 1st Reading A558nm Alkalinity (hrs) Problem R7Bik 1 0 7217 7 801 8 .977E-05 0.63 0.000 0 .000 2 0 .7193 7 .797 8.896E-05 1 .87 3 0 7187 7 .796 8.876E-05 4.75 4 0 .7181 7 .795 8.856E-05 7 .10 R2 1 0.6779 7.724 7.642E-05 0.70 no 2 0.6520 7 .679 6 .965E-05 2.12 weight 3 0.6303 7 .643 6 451 E-05 4 .83 4 0.6234 7 .632 6 .296E-05 7.17 R3 1 0 .7009 7 .764 8 31 OE-05 0 .93 -7.20E-05 -5.53E-05 2 0.6834 7 .733 7 .796E-05 2 .30 3 0 .6645 7 701 7 .283E-05 5 .07 4 0.6563 7 .687 7 .073E-05 7.48 R1 1 0.6759 7 .720 7 .587E-05 0.83 -7.55E-05 -5.63E-05 2 0 .6575 7 .689 7 .103E-05 2.23 3 0.6417 7 .662 6 .716E-05 4.97 4 0 .6324 7 .647 6.499E-05 7 .35 R5 1 0. 7065 7.774 8 .483E-05 1.07 3 2 7E-05 -2. 79E-05 2 0 .6988 7 .760 8 .246E-05 2 .42 3 0.6887 7.742 7 .947E-05 5.15 4 0 .6827 7 .732 7.776E-05 7 .65

PAGE 196

APPENDIX 7 (Continued} 175 Table 83 Pyrite hydrogen ion evolution in seawater .(11-9-86) Cuvet Total T i me All data 1st data Reading A558nm Alkalinity (hrs) 6TA*/td 6TA*/6t Prob lem TO Blk 1 0 .7308 7.817 9.292E-05 0.58 0.000 0.000 2 0 7299 7.815 9.261 E-05 3.70 3 0.7308 7.817 9 .292E-05 5.83 4 0 7306 7.817 9.285E-05 7 .83 T1 1 0.6890 7.742 7 .958E-05 0 .85 -5 79E-05 -3.55E-05 2 0 .6640 7 .699 7.272E-05 3.78 3 0.6569 7.687 7.089E-05 5 .88 4 0.6491 7.674 6 .895E-05 7.93 T4 1 0 71 00 7 .779 8 .596E-05 0 .95 -5.82E-05 -3 .83E-05 2 0.6864 7.738 7 .883E-05 3.90 3 0 .6785 7.724 7 661 E-05 6.00 4 0.6705 7 710 7 .443E-05 8.08 T5 1 0.6956 7 .754 8 .152E-05 0.68 2 .34E-05 -2.19E-05 2 0 .6870 7.739 7.900E-05 4 .05 3 0.6809 7.728 7.727E-05 6 .07 4 0.6769 7. 721 7.617E-05 8 .23 T7 1 0 .6889 7.742 7.955E-05 1 .15 -3.62E-05 2. 76E-05 2 0.6720 7. 713 7.483E-05 4.17 3 0 .6636 7 .698 7 .261E-05 6.18 4 0.6572 7.687 7 09 7E-05 8 .42

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APPENDIX 7 (Continued) 1 7 6 Table 84 Pyrite hydrogen ion evolution in 7% 02 ( 11-16-8 6) Cuvet Total Time All data Omit 1st Reading A558nm p-i Alkalinity (hrs) 6TA*/6.t 6TA*/6t Problem AO 1 0 .8846 8.155 1 799E-04 0.82 0 .00 0.00 2 0 8841 8 .153 1 794E04 4 .25 3 0 .8829 8.150 1. 784E-04 16 .25 4 0 .8823 8.148 1. 778E04 21.72 R1 1 0 .8405 8.043 1.458E-04 1.05 -5.14E-05 na 2 0 .8368 8 .035 1.434E-04 4 .35 R4 1 0 .8706 8.117 1.679E-04 1.17 -2.66E-05 na 2 0 .8695 8.115 1 .670E-04 4.53 R7 1 0 .8706 8.117 1.679E-04 1.37 -2.23E-05 1 .39E-05 2 0 .8684 8.112 1.661 E-04 4.65 3 0 .8667 8.107 1.647E-04 17.15 T2 1 0.8619 8 .095 1.61 OE-04 1 72 -1.24E-04 -9. 72E-05 2 0 .8509 8 .068 1 .529E-04 4.72 3 0.8341 8.028 1.417E-04 17 .30 T4 1 0 .8750 8.129 1.715E-04 1.90 -6.09E-05 -5 .01 E-05 2 0.8691 8.113 1 .666E-04 4 .80 3 0 .8606 8 .092 1.600E-04 17.68 4 0 .8574 8 .084 1.576E-04 21.75 T5 1 0 .8699 8.116 1.673E-04 2 .03 -3 .16E-05 -2.63E-05 2 0 .8664 8.107 1 .645E-04 4 .95 3 0 8611 8.093 1.604E-04 17.77 4 0 .8594 8.089 1 591 E-04 21.95 T7 1 0.8636 8.099 1.623E-04 2 .13 -4.38E-05 -3.78E-05 2 0 .8587 8.087 1.586E-04 5 .45 3 0.8500 8.066 1.523E-04 17 .92 4 0.8506 8 .067 1.527E-04 18 .90 5 0.8475 8 .060 1 .505E-04 22.13

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APPENDIX 7 (Continued) 1 7 7 Table 85 Pyrite hydrogen ion evolution in 7% 02 ( 11-19-8 6) Cuvet To t al Time All data Omit 1st Reading A558nm !=H Al kalinity (hrs) Problem RO Blank 1 0 .8775 8 .153 1. 792E-04 0 .75 0 .0000 0 .0000 2 0 .8777 8.154 1. 794E04 4.62 3 0 .8769 8.152 1.786E-04 9 .22 4 0.8761 8 .150 1 779E-04 22.58 R1 1 0 .8454 8 .070 1.533E-04 0.87 2 75E-05 -1.66E-05 Lost 2 0 .8406 8.059 1 .500E-04 4 .82 sample 3 0 .8388 8 .054 1.487E-04 9 .35 4 0 .8365 8 .049 1 .472E-04 22.85 R3 1 0.8367 8 .049 1 .473E-04 0 .93 -6.67E-05 -5.52E-05 2 0 .8312 8 .036 1.437E04 4 .93 3 0 .8257 8 .024 1.402E-04 9.43 4 0 .8186 8 .007 1 .358E-04 22.93 R4 1 0 .8754 8 .148 1 773E-04 1.03 -4 .08E-05 -3 .31 E-05 2 0 .8713 8.137 1. 737E-04 5 .08 3 0.8673 8 .126 1 .703E-04 9.90 4 0 .8626 8 .114 1 .664E-04 23.45 R5 1 0 .8870 8 .180 1.882E-04 1 .15 -8 70E-05 -7 .07E-05 2 0 .8776 8.154 1 .793E-04 5 .16 3 0 .8710 8 .136 1 734E-04 10.07 4 0 .8588 8 .104 1.634E-04 23.65 R7 1 0 .8454 8 .070 1.533E-04 1.21 -5.12E-05 4 .26E-05 2 0.8405 8 .058 1 .499E-04 5 .36 3 0 .8359 8 .047 1 .468E-04 10.20 4 0 .8293 8 .032 1.424E-04 24.73 T4 1 0.8625 8 .113 1 .663E-04 1.20 -3 .60E-05 -3 .07E-05 2 0 .8608 8 .109 1 .650E-04 5.70 3 0 .8589 8 .104 1.635E-04 10.32 4 0.8565 8 .098 1 .616E-04 24.97 T7 1 0 .8599 8 .107 1 .643E-04 1.72 -2.50E-05 -2.07E-05 2 0 .8568 8 .099 1 .618E-04 5.82 3 0 .8542 8 .092 1 .598E-04 10.42 4 0 8501 8 .082 1 .568E-04 25.18

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APPENDIX 7 (Continued) 178 Table 86 Pyrite hydrogen ion evolution in 7% 02 (12-5-86) Cuvet Total Time All data Om i t 1st Reading A558nm Alkalinity (hrs) Problem RO Blank 1 0 .8072 7 .963 1 .247E-04 0 .85 0 .0000 0 .0000 2 0 .8075 7 .964 1 .249E-04 4 .88 3 0 .8018 7 .952 1 .220E-04 19.77 4 0.8010 7 .950 1 .216E-04 23.47 R7 1 0 7830 7.913 1 .129E-04 0.75 -2.43E-05 -2.86E-05 2 0 7828 7 .913 1.128E-04 4 .92 3 0. 7726 7 .892 1.083E-04 19.85 T2 1 0 7802 7.907 1 .117E-04 1.08 -3.03E-05 -2. 31 E-05 2 0 .7652 7 .878 1 .052E-04 5 .03 3 0 7451 7 .839 9 .734E-05 22.40 4 0 7443 7 .838 9.704E-05 24.08 R8 1 0.8033 7 .955 1.227E-04 1 .30 2 0.8017 7 951 1.219E-04 5 .50 weight 3 0 .7982 7 .944 1 .202E-04 22.20 4 0 .7977 7 .943 1 .199E-04 23.63 T4 1 0 7892 7 .926 1 .158E-04 1 .47 -5.87E-05 -5.84E-05 2 0 .7815 7.910 1.123E-04 5 .70 3 0 .7622 7 .872 1 .040E-04 20.92 4 0 7451 7 .839 9.734E-05 22.42 T5 1 0 .7969 7 941 1 .195E-04 1 .63 -1.78E-05 -1.83E-05 2 0 .7953 7 .938 1 .187E-04 5 .83 3 0.7888 7.925 1 .156E-04 20.43 T8 1 0 .8008 7 .949 1.215E-04 1.65 -2.54E-05 -2.56E-05 2 0 .7989 7 .946 1 .205E-04 5 .88 3 0 7919 7 931 1 171 E-04 20.22 R3 1 0. 7816 7 .910 1 .123E-04 1.93 -2.42E-05 -2.15E-05 Lost 2 0 .7760 7 .899 1.098E-04 6 .17 sample 3 0 .7647 7 .877 1.050E-04 21.42 4 0 .7636 7 .875 1.046E-04 23.60 R1 1 0 7831 7.913 1.130E-04 2 .25 -3 .09E-05 -2.91 E-05 2 0 7776 7.902 1 1 05E-04 6 .03 3 0 7612 7 .870 1.036E-04 21.72 4 0. 7594 7 .867 1 .029E-04 23.78 R4 1 0.8024 7.953 1 .223E-04 2 .37 3 .99E-05 -3 77E-05 2 0. 7973 7 .942 1 .197E-04 6 .35 3 0 7831 7 .913 1.130E-04 20.57

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APPENDIX 7 (Continued) 179 Table 87 Pyrite hydrogen ion evolution at low temperature (1-14-87) Cuvet Total T ime All data Omit 1st Read inQ A558nm _Q-l Alkalinity (hrs) 6TA*/6t 6TA*/6t Problem RO B lank 1 0.9143 8 .446 1 .924E-04 3 .88 0.0000 0.0000 2 0 9141 8.446 1.922E -04 21.57 3 0 .9148 8.447 1 .928E-04 25.02 4 0.9135 8.444 1.917E-04 30.05 5 0.9144 8 .446 1.925E-04 33.43 6 0 .9135 8 .444 1.917E-04 45.43 7 0 .9165 8.452 1 .943E-04 50.08 8 0 .9147 8 .447 1.927E-04 53.35 R9 1 0.8575 8 .313 1 .506E-04 4 .17 -1.21 E-06 -4.21 E-07 2 0.8557 8.309 1 .495E-04 21.88 3 0.8545 8 .306 1 .487E-04 30.63 4 0.8545 8.306 1.487E04 45.85 5 0 .8550 8 .307 1.490E-04 53.68 R4 1 0.9058 8.424 1 851 E-04 4.43 -2.87E-06 -1.69E-06 2 0 .9025 8.416 1 .824E-04 22.25 3 0.9021 8.415 1 .821 E-04 31.03 4 0.9009 8.412 1 .811E-04 46.28 5 0.9008 8.412 1 .8 1 OE-04 54.08 R3 1 0.8913 8.389 1. 736E-04 5.02 -3.14E-06 -2.56E-06 2 0 .8884 8.382 1.714E-04 22.55 3 0.8858 8 .376 1 .695E04 31.52 4 0.8847 8.374 1.687E-04 46.82 5 0 .8841 8.372 1.683E-04 56.08 R 7 1 0.9299 8.488 2.070E-04 5.37 -1.17E-05 6.61 E-06 2 0 .9197 8 .460 1 .972E-04 23.00 3 0.9149 8.448 1.929E-04 32.00 4 0.9128 8.442 1.911E04 47.27 5 0.9130 8 .443 1.912E04 54.68 T5 1 0.8858 8.376 1.695E-04 7.08 -1.67E-06 -1.67E-06 2 0.8846 8.373 1.686E-04 23.33 3 0.8831 8 .370 1.676E-04 32.33 4 0.8810 8.365 1 661 E-04 47.68 5 0.8816 8.366 1.665E-04 56.39

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APPENDIX 7 (Continued) 180 Table 87 continued Cuvet Total Time All data Om i t 1st Read ing A558nm P-i Alkalinity {hrs) 6TA*/6t 6TA*/6t Problem T8 1 0 .9176 8.455 1.953E-04 7 .56 -1.85E-06 -1.35E-06 2 0.9139 8 .445 1 .920E-04 23.73 3 0 .9128 8.442 1 .911E-04 32.66 4 0 .9116 8.439 1.900E-04 48.18 5 0.9103 8 .436 1 .889E-04 57.81 6 0 .9100 8 .435 1 .886E-04 70.26 T4 1 0 .9117 8 .439 1 .901E-04 8.40 -3.04E-06 -2.38E-06 2 0 .9069 8 .427 1.860E-04 24.65 3 0.9055 8.424 1 .848E-04 33.47 4 0 .9021 8 .415 1 821 E -04 49.48 5 0 .9026 8.417 1 .825E-04 54.88 T2 1 0.8871 8 .379 1 705E04 8 .58 -4. 74E-06 3 .99E-06 2 0 .8833 8 .370 1 .677E-04 24.42 3 0.8808 8 .365 1 .659E-04 33.28 4 0 .8784 8 .359 1.642E-04 49.03 5 0.8781 8 .358 1.640E-04 55.35

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APPENDIX 7 (Continued) 181 Table 88 Pyrite hydrogen ion evolution at low temperature (1-19-87) Cuvet Total Time All data Omit 1st Reading A558nm Alkalinity (hrs) f1TA*/ f1t f1TA*/ f1t Problem RO Blk 1 0.9563 8 .535 2 241 E-04 4.55 0 .000 0 .000 2 0.9572 8 .537 2 251 E 04 8.05 3 0.9567 8.536 2 .245E-04 23.93 4 0.9571 8 .537 2 .250E-04 27.18 5 0.9569 8 .537 2.247E-04 30.73 R9 1 0 .9500 8.517 2 .172E04 4.82 -9.87E-06 -9.14E-06 outlier 2 0 .9438 8.499 2 1 09E-04 24.22 3 0 .9427 8 .496 2 .098E-04 31.08 4 0 .9363 8 .479 2.035E-04 48.55 5 0 9361 8.479 2.033E04 56.73 R7 1 0 .9498 8 .516 2.170E-04 5.15 -8 .05E-06 -6 .75E-06 2 0 .9444 8 501 2 .115E-04 24.57 3 0 .9437 8 .499 2 1 08E-04 31.42 4 0.9394 8.487 2 .065E04 48.97 5 0.9394 8.487 2 .065E04 56.05 R1 1 0.9182 8.432 1.873E-04 5.57 -2.87E-06 -2.59E-06 Lost 2 0 .9164 8.428 1 .858E-04 24.97 sample 3 0 .9158 8.426 1.853E04 31.82 4 0 .9146 8.423 1.843E04 49.38 5 0 9141 8.422 1.839E04 55.78 R4 1 0.9393 8.487 2 .064E-04 5.83 -2.46E-06 -1.71E-06 2 0 .9365 8.480 2.037E-04 25.27 3 0.9368 8.480 2 .040E-04 32.15 4 0.9351 8.476 2 .024E04 49.72 R5 1 0 .9690 8.573 2.389E-04 6 .19 -1.96E-05 -1.73E-05 2 0 .9583 8.541 2.263E-04 25.49 3 0.9554 8.532 2.231 E-04 32.49 4 0.9459 8 .505 2 .130E04 51.89 5 0 .9455 8.504 2 .126E-04 56.41 T7 1 0 .9435 8.499 2 1 06E-04 6 .53 -3. 73E-06 3 .30E-06 2 0 .9397 8.488 2.068E-04 25.92 3 0.9381 8.484 2.052E-04 32.87 4 0.9356 8.477 2 .028E-04 52.12 5 0.9346 8.475 2 .019E-04 57.53

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APPENDIX 7 (Continued) 182 Table 88 continued Cuvet Total Time All data Omi t 1st Read ing A558nm p; Alkalinity (hrs) 6TA*/At ATA*/At Problem T5 1 0 .9344 8.474 2 .017E-04 6 .90 -1.67E-06 -9.35E-07 2 0 9321 8.468 1 .996E-04 26.18 3 0 .9309 8 .465 1.985E04 33.16 4 0 .9308 8.465 1 .984E-04 52.39 5 0 .9304 8 .463 1 .980E-04 57.93 T9 1 0 .9495 8 5 1 5 2 .167E-04 7 .25 -1. 78E-06 2 .93E-06 2 0 .9506 8 .518 2.179E-04 26.45 3 0 .9486 8 .513 2 .158E-04 33.47 4 0 .9459 8.505 2 .130E-04 52.67 5 0 .9456 8.504 2 .127E-04 58.23 T2 1 0 .9404 8 .490 2 .075E-04 7 .70 -7.92E-06 -5.31 E -06 2 0 .9348 8 .475 2 021 E-04 26.75 3 0 .9338 8.472 2 .011E-04 33.83 4 0 .9318 8 .467 1 .993E-04 53.15 5 0.9309 8.465 1 .985E04 55.37

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APPENDIX 7 (Continued) 183 Table 89 Pyrite hydrogen ion evolution at low temperature ( 1-2 5-8 7) Cuvet To tal Time A ll d ata Omit 1st Proble m Read ing A558n m Alkalinity (hrs) R1 Blan k 1 0 7869 8.179 1 .155E-04 4.48 0.000 0.000 2 0 7861 8 .177 1 .152E-04 27.03 3 0 .7863 8 .177 1 .153E-04 30.15 4 0.7837 8 173 1 .142E-04 47.92 5 0 7838 8 .173 1.142E-04 55.32 6 0 7838 8.173 1 .142E-04 71.02 R7 1 0 .8214 8 .245 1 .3 16E-04 4.78 -4 .32E-06 3 .33E-06 2 0.8123 8.227 1 .271 E -0 4 27.30 3 0.8076 8 .218 1.248E-04 48.20 4 0.805 8 8 .214 1.240E-04 55.65 5 0.8028 8.209 1.226E 04 71.27 R3 1 0. 7991 8.202 1.209E04 5.12 1 .09E-05 -9.30E-06 outlier 2 0. 7863 8.177 1 .153E04 27.65 3 0. 7763 8.159 1.111E-04 48.58 4 0.7740 8.155 1.102E-04 56.02 5 0 .7683 8 .144 1 .080E-04 71.62 AS 1 0 .8063 8.215 1.242E-04 5.36 -4.18E-06 3 57E-06 2 0 7961 8.196 1 196E-04 27.90 3 0 7892 8.183 1 1 65 E-04 48.90 4 0. 7854 8.176 1 149E-04 56.30 5 0 7818 8.169 1 .134E-04 73.70 T7 1 0 .8197 8 .242 1.307E-04 5 .79 5.49E-06 4 .41 E-06 2 0 .8080 8.219 1.250E-04 28.51 3 0.8020 8.20 7 1.222E-04 49.44 4 0 7995 8.202 1.211E-04 57.36 5 0. 7946 8 193 1 .189E-04 72.59 T9 1 0. 7844 8 .174 1. 14 5E-04 5.47 -1.77E-06 -1.39E-06 2 0.7804 8.167 1. 128E-04 28.13 3 0 7782 8 .162 1.119E-04 49.07 4 0 7778 8 162 1 .117E-04 56.47 5 0. 7761 8 159 1.111E-04 71.83 T 5 1 0 .8175 8.237 1.296E-04 6.23 -3.20E-0 6 -3.00E-06 2 0.8123 8 .227 1 .271 E-04 29.00 3 0.8085 8 .220 1 .253E-04 49.75 4 0.8071 8 .217 1.246E-04 57.73 5 0.8039 8 211 1.231E-04 72.25

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APPENDIX 7 (Continued) 184 .Table 89 continued Cuvet Total Time All data Omit 1st Problem Reading A558nm Alkalinity (hrs) T2 1 0 .7967 8 .197 1.198E-04 6 .38 -3.58E-06 -2.42E-06 2 0 7811 8 .168 1 .131E-04 29.48 3 0.7743 8 .155 1.1 03E -04 50.10 4 0.7713 8.150 1 .091 E-04 58.12 5 0. 7682 8.144 1 .079E-04 74.00 T4 1 0. 7906 8.186 1 171 E-04 6 .58 1 .87E-06 2 .01 E-06 2 0. 7876 8 .180 1.158E-04 29.80 3 0 7841 8.173 1 .144E-04 51.18 4 0 7830 8.171 1 .139E-04 58.35 5 0.7803 8 .166 1 .128E04 73.33

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APPENDIX 7 (Continued) 185 Table 90 Parameters used to calculate total alkalinity Experiment pKd Cell temp Salinity A max Phenol red Borate 0.7M NaCI (kelvin) 558 nm moles/kg moles/kg 10/4/86 7 .490981 298.15 1 .1530 2.115E-06 3 .043E-04 1 0/5/8 6 7 .490981 298.15 1 1 529 2 .120E-06 3 .043E-04 1 0/8/8 6 7.490981 298.15 1 .034 7 1 .923E-06 3.042E-04 10/10/86 7.490981 298.15 1.2599 2 .324E-06 3 .042E-04 10/14/86 7.490981 298.15 1.1 328 2 121 E-06 3 .043E-04 1 0/13/86 7.490981 298.15 1.1287 2 .114E-06 3 .043E-04 10/16/86 7 .490981 298.15 1 .1321 2 .118E-06 3 .043E-04 10/17/86 7 .490981 298.15 1.2448 2 .326E-06 3.043E-04 Seawater 10/28/86 7.493789 298.15 34.298 1.1332 2 .094E-06 8.455E-04 10/29/86 7.493789 298.15 34.298 1.1332 2.094E-06 8.455E-04 10/31/86 7.494269 298.1 34.298 1.0800 1 .984E-06 8.455E-04 11/3/86 7.493981 298.13 34.298 1 .0799 1.984E-06 8.455E-04 11 / 4 /86 7.494748 298. 05 34.298 1 .0784 1.981 E-06 8.455E-04 11/8/86 7.494748 298.05 34.298 1.0781 1 .980E-06 8.455E-04 11/9/86 7.493701 298.15 34.32 1.0779 1 .980E-06 8.455E-04 11/13/86 7.494660 298. 05 34.32 1.0787 1.981 E-06 8.459E-04 7% oxygen 11/19/86 7.494660 298.05 34.32 1.0700 1.965E-06 8 .459E-04 11/16/86 7.493701 298.15 34.32 1 .0777 1 .980E-06 8.459E-04 1 2/5/86 7.493701 298.15 34.32 1.0812 1.986E-06 8.459E-04 1 2/9/86 7.493701 298.15 34.32 1 .0807 1 .985E-06 8 .459E-04 12/13/86 7.494181 298.1 34.32 1.0783 1 981 E -06 8.459E-04 12/17/86 7.497066 297.8 34.32 1.0788 1 981 E-06 8.459E-04 low temp 12/22/86 7 .793606 275.69 34.32 1 .1262 1.986E-06 8.459E-04 1/3/86 7.802716 275.11 34.32 1 .11 67 1.967E-06 8.459E-04 1/14/86 7 .799721 275.3 34.32 1 .1207 1 .975E-06 8.459E-04 1/19/86 7.801138 275.21 34.32 1.1328 1 .997E-06 8 .459E-04 1/25/86 7 .802716 275.11 34.32 1.1181 1 .969E-06 8.459E-04 1/31/86 7.799721 275. 3 34.32 1.1196 1.973E-06 8.459E-04

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APPENDIX 7 (Continued) 186 Table 90 continued Experiment Ionic Temp log BHS04 ln(BHF) [504] BHF Strength K (BHS04) moles/kg Seawater 10/28/86 0 71 298.15 1.0783 11.9753 6 .0225 0.0275 412.5904 10/29/86 0.71 298.15 1 .0783 11 .9753 6 .0225 0 .0275 412.5904 10/31/86 0.71 298.10 1 .0777 11 .9590 6 .0216 0 .0275 412.2214 11/3/86 0 71 298.13 1 .0781 1 1 .9688 6 .0221 0.0275 412.4428 1 1/4/86 0 71 298.05 1 .0771 11.9428 6 .0207 0 .0275 411.8527 1 1/8/86 0.71 298.05 1 .0771 11.9428 6 .0207 0 .0275 411.8527 1 1/9/86 0.71 298.15 1.0783 11.9753 6 .0225 0 .0275 412.5904 11/13/86 0.71 298.05 1.0771 11.9428 6.0207 0 .0275 411 .8527 7% oxygen 11/19/86 0 71 298.05 1.0771 11 .9428 6 .0207 0.0275 411 .8527 11/16/86 0.71 298.15 1.0783 11.9753 6.0225 0 .0275 412.5904 12/5/86 0.71 298.15 1 .0783 11.9753 6.0225 0 .0275 412.5904 12/9/86 0.71 298.15 1 .0783 11.9753 6.0225 0 .0275 412.5904 12/13/86 0.71 298.10 1.0777 11.9590 6.0216 0 .0275 412.2214 12/17/86 0. 71 297.80 1.0742 1 1 .8620 6 .0162 0 .0275 410.0121 Low temp 12/22/86 0. 71 275.69 0.8266 6.7079 5 .5879 0 .0275 267.1845 1/3/86 0.71 275.11 0 .8205 6 .6141 5 .5758 0 .0275 263.9550 1/14/86 0.71 275.30 0.8225 6.6447 5 .5798 0 .0275 265.0101 1/1 9/86 0.71 275.21 0 .8215 6.6302 5 .5779 0 .0275 264.5100 1/25/86 0 71 275.11 0.8205 6 .6141 5 .5758 0.0275 263.9550 1/31/86 0 71 275.30 0 .8225 6 .6447 5 .5798 0.0275 265.0101 0 .7M NaCI 10/4/86 0 7 298.15 10/5/86 0 7 298.15 10/8/86 0.7 298.15 10/10/86 0.7 298.15 10/13/86 0 7 298.15 10/14/86 0 7 298.15 10/16/86 0 7 298.15 10/17/86 0 7 298.15

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APPENDIX 7 (Continued) 187 Table 90 continued Experiment [F] opKB pKb pKb pKw factor moles/kg free H sws sws Seawater 1 0 /28/86 8.2600E-05 1.3462E-01 8 7490 8 .6143 13.1998 1 .3634 1 0/29/86 8 .2600E-05 1 .3462E-01 8.7490 8 .6143 13. 1 998 1 .3634 10/31/86 8.2700E-05 1.3448E-01 8 .7493 8.6148 13.2017 1 .3630 11/3/86 8 .2700E-05 1 .3458E-01 8 7491 8.6145 13.2005 1 .3633 11/4/86 8 .2700E-05 1 .3433E-01 8. 7497 8.6154 13.2036 1 .3625 11 / 8 /86 8.2700E-05 1.3433E-01 8. 7497 8.6154 13.2036 1 .3625 11 / 9 /86 8 .2700E-05 1 .3464E-01 8 .7488 8.6142 13.1 998 1 .3634 11 /13/86 8 .2700E-05 1 .3433E-01 8 7496 8 .6152 13.2036 1.3625 7% oxygen 11 /19/86 8.2700E-05 1 .3433E-01 8 .7496 8.6152 1 3 .2036 1 .3625 11 /16/86 8.2700E-05 1.3464E-01 8 .7488 8.6142 13.1 998 1.3634 12/5/86 8 .2700E-05 1 .3464E-01 8 .7488 8 .6142 13.1998 1.3634 1 2 / 9 /86 8 .2700E-05 1 .3464E-01 8 .7488 8.6142 13.1998 1.3634 12/13/86 8.2700E-05 1 .3448E-01 8. 7492 8 .6147 13.2017 1.3630 12/17/86 8 .2700E-05 1 .3358E-01 8.7514 8.6179 13.2133 1.3601 Low temp 12/22/86 8 .2700E-05 8 .1550E-02 8 .9813 8.8998 14.1400 1.2066 1/3/86 8.2700E-05 8.0524E-02 8 .9803 8.8998 14.1663 1.2037 1 /14/86 8.2700E-05 8 .0859E-02 8.9866 8.9057 14.1577 1.2046 1 / 1 9 /86 8.2700E-05 8 .0700E0 2 8.9878 8.9071 14.1618 1.2042 1 /25/86 8 .2700E-05 8.0524E-02 8.9892 8.9087 14.1 663 1 .2037 1/31/86 8.2700E-05 8 .0859E-02 8.9866 8.9057 14.1577 1 .2046 pKb pKw (NaCI) (NaCI) 0 .7M NaCI 8.85 13.77 1 0 / 4 /86 8.85 13.77 1 0 / 5 /86 8.85 13.77 1 0 / 8/86 8.85 13.77 10/10/86 8.85 13.77 10/13/86 8 .85 13.77 10/14/86 8.85 13.77 10/16/86 8.85 13.77 10/17/86 8.85 13.77

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APPENDIX 7 (Continued) 1 8 8 Table 91 Marcasite hydrogen ion evolution in 0.7 M NaCI Summary of results Study 1 All data Omit 1st Experiment means pH Initial 1 0/4/86 -2.503E-05 7 .839 1 763E-05 1 0 /5/86 -6. 709E-06 7 .875 -5.276E-06 1 0/8/86 -7.020E-06 7.764 -5.638E-06 10/10/86 -8.066E-06 7 .849 -6.263E-06 Mean of exp means 1 .171E-05 7 .832 -8. 701 E-06 Standard deviation 8 .902E-06 0 .047 5 .964E-06 Mean of all cuvets -1.135E-05 7 .826 -8.465E-06 Standard deviation 1.134E-05 0.049 7 .640E-06 P standard deviat ion 1.089E05 0 .047 7 .340E-06 Standard error 3 021 E-06 0 .013 2 .036E-06 Outlier omitted Experiment means 1 0 / 4 /86 -1.39E-05 7 .85 -1.03E-05 1 0 / 5 /86 -6.71 E-06 7.87 -5.28E-06 10/ 8 /86 -7.02E-06 7 .76 -5.64E-06 10/10/86 8 .07E-06 7 .85 6 .26E-06 Mean of exp means 8 .92E06 7 .84 -6.86E-06 Standard dev i ation 3.37E-06 0 .05 2.31 E-06 Mean of all cuvets -8.35E06 7 .83 -6.48E-06 Standard deviat ion 3 .61 E-06 0 .05 2 74E-06 P standard dev i ation 3.45E-06 0 .05 2 .62E-06 Standard error 9 .97E-07 0.01 7.58E-07

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APPENDIX 7 (Continued) Table 92 Marcasite hydrogen ion evolution in seawater Summary of results Study 2 All data Omit 1st Experiment means t1TA*/t1t pH Initial t1TA*/l1t 10/31/86 -1.15E05 7.32 -7 .52E06 11/3/86 -5.45E-05 7 .78 -3 .15E05 11/4/86 -4.73E-05 7 .65 -2 .73E-05 11/13/86 -2.06E-05 7.47 -1.16E-05 Mean of exp. means 3 .35E-05 7.55 1.95E-05 Standard deviation 2 .07E-05 0.20 1 .17E-05 Mean of all cuvets 3 1 6E-05 7.55 -1.86E-05 S t andard deviation 3 .16E-05 0.19 1 .78E-05 P standard deviation 3 .06E05 0.18 1.72E-05 Standard error 7 64E 06 0.04 4.30E-06 Table 93 Marcasite hydrogen ion evolution in 7% 02 Summary of results Study 3 All data Omit 1st Experiment means l1TA*/l1t pH Initial l1TA*/l1t 12/9/86 1.1 OE05 7 .75 8 70E-06 12/13/86 -1.09E-05 8.10 -8.08E-06 Mean of exp means -1.09E-05 7.93 -8.39E-06 Standard devi a tion 1 .03E07 0.24 4.41 E -07 Mean of all cuvets -1.09E05 7 .92 -8.40E-06 Standard d e viation 3.39E-06 0.18 2.98E-06 P standard deviation 3.30E-06 0.17 2.90E-06 Standard error 7.58 E -07 0.04 6.66E-07 189

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APPENDIX 7 (Continued) Table 94 Marcasite hydrogen ion evolution at low temperature Summary of results Study 4 All data Omit 1st Experiment means 6TA*/6t pH Initial 6TA*/6t 12/22/86 -1.475E-06 7 .91 -8.971 E-07 1/3/87 -1.681E-06 8 .07 -1.875E-06 1/31/87 -3 .394E-06 8 .28 -3. 768E-06 Mean of exp means 2 .183E-06 8.08 -2.180E-06 Standard deviation 1.053E-06 0.19 1.459E-06 Mean of all cuvets -2.054E-06 8 .04 -1.912E-06 Standard deviation 2 .126E-06 0.16 2 .687E-06 P standard deviation 2 .066E-06 0.16 2 611 E-06 Standard error 4 871 E-07 0.04 6.155E-07 Outlier om ltted Experiment means 12/22/86 -1 .4 7E-06 7 .91 -8.97E-07 1/3/87 -1.68E-06 8 .07 -1.88E-06 1/31/87 -2.00E-06 8.28 -1.69E-06 Mean of exp means -1. 72E-06 8 .08 -1.49E-06 Standard deviation 2 .63E-07 0 .19 5.19E-07 Mean of all cuvets 1 .65E-06 8.03 -1.31E-06 Standard deviation 1 .28E-06 0.16 9 .06E-07 P standard deviation 1 .24E-06 0.15 8 .79E-07 Standard error 3 .01 E-07 0.04 2 .13E-07 190

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APPENDIX 7 (Continued) Table 95 Pyrite hydrogen ion evolution in 0.7 M NaCI -Summary of results Study 1 All data Omit 1st Experiment means t.TA*/t.t pH Initial t.TA*/t.t 10/13/86 -1.06E-05 7.70 -8.63E-06 10/14/86 -4.16E-05 7.72 2 31 E-05 10/16/86 -1.38E-05 7.84 -1.14E-05 10/17/86 -4.40E-05 7 .87 -2.07E-05 Mean of exp means -2.75E-05 7.78 -1.59E-05 Standard deviation 1 .77E-05 0.09 7.02E-06 Mean of all cuvets -2.84E-05 7.78 -1.62E-05 Standard deviation 2.76E-05 0 .12 1 .23E-05 P standard deviation 2 .67E-05 0 .12 1.18E-05 Standard error 6 .89E-06 0 .03 3.06E-06 Table 96 Pyrite hydrogen ion evolution in seawater -Summary of results Study 2 All data Omit 1st Experiment means t.TA*/t.t pH Initial t.TA*/t.t 1 0/28/ 8 6 -2.811E-05 7.58 -2.459E-05 1 0/29 / 8 6 -5.313E-05 7.88 11/8/86 -6.006E-05 7.75 -4.650E-05 11/9/86 -4.393E-05 7 .75 -3.080E-05 Mean of exp means -4.631 E -05 7 .74 3 .397E-05 Standard deviation 1.381 E-05 0 .12 1 .129E-05 Mean of all cuvets -4.484E-05 7 .73 -3.283E-05 Standard deviation 2 .050E-05 0.11 1.369E-05 P standard deviation 1 .975E-05 0 .11 1 .306E-05 Standard error 5 .279E-06 0 .03 3.936E-06 19 1

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APPENDIX 7 (Continued) 1 9 2 Table 97 Pyrite hydrogen ion evolution in 7% 02 Summary of results Study 3 All data Omit 1st Experiment means pH Initial 11 /16/86 -5.1SOE-05 8.09 -4.506E-05 11 /19/86 -5.11 OE-05 8.11 -4.218E-05 12/ 5 /86 -3.248E-05 7.93 -3.155E-05 Mean of exp means -4.503E-05 8 .04 -3.960E-05 Standard deviation 1 .087E-05 0 .10 7 118E-06 Mean of all cuvets -4.473E-05 8 .04 -3.885E-05 Standard deviation 2.564E-05 0.09 2.095E-05 p standard deviation 2 .500E-05 0 .09 2.036E-05 Standard error 5.589E-06 0.02 4 799E-06 Outlier omitted Experiment means 11/16/ 8 6 -3.945E-05 8.09 -3.204E-05 11/19/86 -5.11 OE-05 8. 11 -4.218E-05 1 2/5/8 6 -3. 248E-05 7.93 -3.155E-05 Mean of exp means -4.101E-05 8.04 -3.526E-05 Standard deviation 9.408E06 0.10 6.005E-06 Mean of all cuvets -4.056E-05 8.04 -3.542E-05 Standard deviation 1.811E-05 0 .09 1.554E-05 p standard deviation 1 .763E05 0 .09 1.507E-05 Standard error 4.044E06 0.02 3.656E-06

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APPENDIX 7 (Continued) 1 9 3 Table 98 Pyrite hydrogen ion evolution at low temperature Summary of results Study 4 All data Omit 1st Experiment means 6TA*/6t pH Initial 6TA*/6t 1 /14/87 -4.197E-06 8.40 -2. 793E-06 1/16/87 6 .879E-06 8.51 -5.919E-06 1/25/87 -4.776E-06 8.22 -3.918E-06 Mean of exp means -5.284E-06 8 .38 -4.21 OE-06 Standard deviation 1.411 E-06 0 .15 1 .584E-06 Mean of all cuvets -5.501 E -06 8 .77 -4.455E-06 Standard deviation 4.481E-06 0.14 3 .799E-06 P standard deviation 4.373E-06 0 .13 3 .707E-06 Standard error 9 .543E-07 0.03 8 .090E-07 Outlier omitted Experiment means 1/14/87 -4.197E-06 8.40 -2. 793E-06 1 /16/87 -6.451 E 06 8 51 -5.459E-06 1/25/8 7 -3. 755E-06 8 .22 -3. 021 E-06 Mean of exp means -4. 801 E-06 8 .38 3 758E-06 Standard deviation 1 .446E-06 0 .15 1.478E-06 Mean of all cuvets 4 .986E-06 8 .37 -3.953E-06 Standard deviation 4 .372E-06 0 .13 3 .618E-06 P standard deviation 4.255E06 0.13 3 .522E-06 Standard error 9 .763E07 0 .03 8 .079E-07

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194 APPENDIX 8 PRELIMINARY WORK WITH OTHER SULFIDES Colorimetric experiments with phenol red Neither sphalerite (ZnS) nor chalcopyrite (CuFeS1.9) when incubated in the same seawater/phenol red solution as used for pyrite and marcasite hydrogen ion evolution rate experiments, produced any measurable absorbance change distinguishable from those seen with blank solutions This type of expe riment was not pursued However, it is possible that adjustment of experiment parameters may allow spectrophotometric observation of these minerals. Colorimetric experiments with PAR Trial experiments with 4-(2-pyridylazo)resorcinol, monosodium salt hydrate (PAR) were also performed. PAR chelates metals, forming a colored complex. It was found by examining the spectra of ZnCb -PAR solutions in carbonate free borate buffered seawater that the Zn-PAR peak maximum was at 535 nm. When sphalerite was incubated in PAR/seawater solutions in spectrophotometric cells, the absorbance of this peak at 535 nm

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APPENDIX 8 (Continued) 195 increased with time. The results of trial experiments with sphalerite, incubated in PAR/seawater at 25C are shown in Table 99. The rate decreases with time in experiment 2. For experiment 1, compared with blank PAR-seawater solution (no sphalerite) there was a large initial increase in absorbance after addition of sphalerite; this was eliminated in experiment 2 by pre-washing the sample with PAR solution. The absorbance reading of blank PAR-seawater solution varied ; it was found that bubbling with the 7% oxygen balance nitrogen air mixture stabilized the absorbance. This indicates that the absorbance changes were probably due to atmospheric carbon dioxide dissolving in the PAR/seawater solution since the absorbance of PAR is pH sensitive The aeration requirement made the experiment difficult and it was not pursued.

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APPENDIX 8 (Continued) 196 Table 99 Sphalerite oxidation Experiment g sphalerite/ Incubation dA535nm/hr [Zn]/hr gSW time {hrs} moles/kgSW /hr 11 4 04 x w-3 21.5 0.0010 1.0 x w-8 22 3.35 x w-3 16.7 0.0047 4 7 x w-8 22 3.35 x w 3 23 9 0.0041 4.1 x w-8 22 3.35 x w-3 42.0 0 .0037 3.7 x w-8 32 3.99 x w-3 12.93 0.0052 5 2 x w-8 32 3 .99 x to-3 18.65 0.0050 5.o x w-8 32 3.99 x w-3 25.48 0 .0057 5.7 x w-8 1 Unwashed and not aerated. 2 Pre-washed and aerated

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APPENDIX 9 CALCULATION OF DISSOLUTION TIMES OF PARTICLES OF MARCASITE AND PYRITE 197 The assumption is made that the particles are spherical and that the rate of dissolution per unit surface area does not change as the particle dissolves. The volume of a sphere is expressed as : ( 4 7) V = 4/3 7t r3, where r ts radius. Taking the derivative with respect to the radius gtves: ( 48) dV/dr = 47t r2, which can be expressed as: ( 49) dV = 47t r2 dr Differentiating this expressiOn with respect to time (t) gtves: (50) dV/dt = 47t r2 dr/dt. Equation 50 can also be expressed as:

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APPENDIX 9 (Continued) 198 (51) (dV/dt)/47t r2 = dr/dt. Since 47t r2 is equal to surface area and the rate dV /dt can be expressed as (dm/dt)1/p, where m is mass and p is density, equation 51 can be written as: (52) ((dm/dt)/47t r2)(1/p) = dr/dt. The expressiOn (dm/dt)/47t r2 is an equivalent form to the rates listed in Tables 3 and 4. Replacing (dm/dt)/47t r2 with R, the rate from Tables 3 and 4 expressed in terms of g Fe101aJim2FeS2,/hr, gives: (53) R/p = dr/dt. Rearranging equation 53 gives: (54) R/p dt = dr. Taking the integral gtves: (55) tr = pri/R where tr is time m hours it takes to dissolve a particle of radius ri at rate R.