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Gold mining in a tropical rainforest

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Title:
Gold mining in a tropical rainforest mercury sorption to soils in the mining region of Arakaka-Mathew's Ridge, Guyana
Physical Description:
Book
Language:
English
Creator:
Howard, Joniqua A'ja
Publisher:
University of South Florida
Place of Publication:
Tampa, Fla
Publication Date:

Subjects

Subjects / Keywords:
Iron oxide -- batch equilibrium sorption
Batch equilibrium sorption
Cold vapor analysis
THg
TLM
Dissertations, Academic -- Environmental Engineering -- Masters -- USF
Genre:
bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )

Notes

Abstract:
ABSTRACT: Gold mining by artisinal (small-medium scale) miners causes an immense amount of damage to the environment (i.e. soil erosion, mobilization of heavy metals, etc.).1, 2 One of the most popular gold mining techniques employed by artisinal miners in Guyana is mercury amalgamation. During the amalgamation process approximately 300 metric tons/yr 11, 12 of mercury is used. Mercury once in the environment can be transported through the air, soil, and water column. It is estimated that 90-99% of total mercury (THg) is associated with the sediment. An understanding of the geochemical conditions that affect the fate of mercury in soils, which can act as potential sinks or sources for mercury, can provide solutions for reduced environmental impacts of mercury contamination. Local Guyanese agencies have become concerned with the quality of the water, soil, biota, and human impact in remote locations in the interior of Guyana.^ ^Therefore, soil samples were collected from two local mines in Guyana's Arakaka-Mathew's Ridge area. Two soil samples (Pakera Creek and Philip's Mine) and a commercially available iron-oxide sorbent, Kemiron, underwent CVAAS, BET surface area analysis, electron dispersion spectroscopy, and x-ray diffractometry. THg concentrations for recovered soil samples were approximately 300 ng/kg. In addition, samples were subjected to batch equilibrium sorption studies as a function of pH and mercury species/concentration added as Hg(NO3)2 and HgCl2. All samples showed significant amounts of sorption between pH 3-9 for 100-1,000 ppb Hg added as Hg(NO3)2. When HgCl2.was added to the batch reactor containing Kemiron, an iron-oxide surface, the adsorption behavior of Hg2+ decreased. Philip's Mine solids, characterized as silicon dioxide by BET, had the lowest surface area (4 m2/g) and sorption when added as Hg(NO3)2 and HgCl2.^ ^On the other hand, Kemiron and Pakera Creek displayed similar sorption behaviors with high sorption across all pH ranges. This may be due to similar chemistry and larger surface areas. Surface loadings were 200 mg/kg and 2,000 mg/kg for experiments with 100 ppb Hg and 1,000 ppb Hg, respectively. Further analysis is required to identify the binding mechanisms between mercury and samples as well as the role of organic matter content on samples.
Thesis:
Thesis (M.S. Env. E.)--University of South Florida, 2006.
Bibliography:
Includes bibliographical references.
System Details:
System requirements: World Wide Web browser and PDF reader.
System Details:
Mode of access: World Wide Web.
Statement of Responsibility:
by Joniqua A'ja Howard.
General Note:
Title from PDF of title page.
General Note:
Document formatted into pages; contains 65 pages.

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University of South Florida Library
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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 - 001916312
oclc - 181099602
usfldc doi - E14-SFE0001797
usfldc handle - e14.1797
System ID:
SFS0026115:00001


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ABSTRACT: Gold mining by artisinal (small-medium scale) miners causes an immense amount of damage to the environment (i.e. soil erosion, mobilization of heavy metals, etc.).1, 2 One of the most popular gold mining techniques employed by artisinal miners in Guyana is mercury amalgamation. During the amalgamation process approximately 300 metric tons/yr 11, 12 of mercury is used. Mercury once in the environment can be transported through the air, soil, and water column. It is estimated that 90-99% of total mercury (THg) is associated with the sediment. An understanding of the geochemical conditions that affect the fate of mercury in soils, which can act as potential sinks or sources for mercury, can provide solutions for reduced environmental impacts of mercury contamination. Local Guyanese agencies have become concerned with the quality of the water, soil, biota, and human impact in remote locations in the interior of Guyana.^ ^Therefore, soil samples were collected from two local mines in Guyana's Arakaka-Mathew's Ridge area. Two soil samples (Pakera Creek and Philip's Mine) and a commercially available iron-oxide sorbent, Kemiron, underwent CVAAS, BET surface area analysis, electron dispersion spectroscopy, and x-ray diffractometry. THg concentrations for recovered soil samples were approximately 300 ng/kg. In addition, samples were subjected to batch equilibrium sorption studies as a function of pH and mercury species/concentration added as Hg(NO3)2 and HgCl2. All samples showed significant amounts of sorption between pH 3-9 for 100-1,000 ppb Hg added as Hg(NO3)2. When HgCl2.was added to the batch reactor containing Kemiron, an iron-oxide surface, the adsorption behavior of Hg2+ decreased. Philip's Mine solids, characterized as silicon dioxide by BET, had the lowest surface area (4 m2/g) and sorption when added as Hg(NO3)2 and HgCl2.^ ^On the other hand, Kemiron and Pakera Creek displayed similar sorption behaviors with high sorption across all pH ranges. This may be due to similar chemistry and larger surface areas. Surface loadings were 200 mg/kg and 2,000 mg/kg for experiments with 100 ppb Hg and 1,000 ppb Hg, respectively. Further analysis is required to identify the binding mechanisms between mercury and samples as well as the role of organic matter content on samples.
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Gold Mining in a Tropical Rainforest: Mercury Sorption to Soils in the Mining Re gion of Arakaka-Matthew's Ridge, Guyana by Joniqua A'ja Howard A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering Department of Civil and Environmental Engineering College of Engineering University of South Florida Major Professor: Maya Trotz, Ph.D. Daniel Yeh, Ph.D. Nooren Poor, Ph.D. Date of Approval: September 16, 2006 Keywords: iron oxide, batch equilibrium sorption, cold vapor analysis, THg,TLM Copyright 2006, Joniqua A'ja Howard

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DEDICATION This is for my ancestors, grandparents, and the many storms I encountered. Sankofa!

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ACKNOWLEDGEMENTS It is God who arms me with strength and ma kes my way perfect. He makes my feet like the feet of a deer; he enables me to stand on the heights,broaden the path beneath me, so that my ankles do not turnpursue my enemies and overtake them ;.. and crush them so that they could not rise... Psalms 18-32-36Also, I must extend my deepest gratitude a nd appreciation for my major professor, Dr. Maya Trotz, and my committee members (D r. Poor and Dr. Yeh) for helping me formulate my thesis and challenging me thr oughout this period. Special thanks to my family, close spiritual cheerleaders (Erlande Omisca and Quenton Bonds), my Bridge to Doctorate Family, Mr. Benard Batson, and my lab buddies (Melody Nocon, Mike Austin Roe, and Douglas Oti) for all their suppor t during this challe nging time. Most importantly I must thank the National Scie nce Foundations Bridge to Doctorate and GK12 STARS programs for the financial support. Remember this: Whoever sows sparingly wi ll also reap sparingly, and whoever sows generously will also reap generously. 2 Cor. 9:6, NIV.

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i TABLE OF CONTENTS LIST OF TABLES.............................................................................................................iii LIST OF FIGURES.............................................................................................................v ABSTRACT......................................................................................................................v ii CHAPTER 1: INTRODUCTION........................................................................................1 1.1 Motivation and Research Objectives ...............................................................1 1.2 Scope of Work and Approach...........................................................................2 CHAPTER 2: BACKGROUND..........................................................................................3 2.1 Introduction.......................................................................................................3 2.2 Mercury and its Health Effects..........................................................................3 2.3 Mercury and its Uses.........................................................................................5 2.4 Impacts of Artisinal Gold Mining in South America.........................................6 2.5 Mercury Fate in the Aquatic Environment........................................................8 2.5.1 Mercury Sorption.................................................................................9 2.6 Guyana.............................................................................................................13 CHAPTER 3: MATERIALS AND METHODS...............................................................17 3.1 Introduction.....................................................................................................17 3.2 Materials..........................................................................................................17 3.2.1 Glassware.........................................................................................17 3.2.2 Reagents...........................................................................................17 3.2.3 Kemiron/Sediments..........................................................................18

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ii 3.3 Analytical Procedures......................................................................................19 3.3.1 Cold Vapor Atomic Adsorption.......................................................19 3.3.2 Scanning Electron Microsc opy/Electron Dispersive Spectroscopy....................................................................................21 3.4 Batch Equilibrium Sorption Experiments.......................................................21 CHAPTER 4: RESULT S AND DISCUSSION................................................................26 4.1 Introduction.....................................................................................................26 4.2 Total Mercury Analysis..................................................................................26 4.3 BET SEM/EDS and XRD...............................................................................28 4.4 Batch Equilibrium Sorption.............................................................................34 CHAPTER 5: SUMMARY, CONCLUSION, AND RECOMMENDATIONS FOR FUTURE WORK..............................................................................42 5.1 Introduction......................................................................................................42 5.2 Summary of Results and Conclusions.............................................................42 5.3 Recommendations for Future Work................................................................44 REFERENCES..................................................................................................................46 APPENDICES...................................................................................................................54 Appendix A: Abridged Experimental Results.......................................................55

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iii LIST OF TABLES Table 2.1: Current regulatory limits a nd guidelines for mercury set by the US Environmental Protection Agency and the World Health Organization...........4 Table 2.2: Mercury concentra tions in sediment and water samples from different parts of the world...............................................................................................7 Table 2.3: Historical background total mercury concentrations..........................................8 Table 2.4: Content of various elements in soils.................................................................10 Table 3.1: Optimal working conditions fo r Hg determination in sediments using CVAAS............................................................................................................20 Table 3.2: Conditions used for batch adsorption studies (1000 ppb Hg = 0.5E-5M)...............................................................................22 Table 3.3: Formation constants for Hg 2+ species, Log Ks for ionic strength...................23 Table 4.1: Total mercury concentrations in Matthews Ridge/Arakaka area....................27 Table 4.2: Summary of batch equilibrium sorption studies...............................................36 Table A.1: 100 ppb Hg (Hg(NO 3 ) 2 ) sorption on 0.1 g Pakera Creek sediment (1.1)..................................................................................................55 Table A.2: 100 ppb Hg (Hg(NO 3 ) 2 ) sorption on 0.1 g Pakera Creek sediment (1.2)..................................................................................................56 Table A.3: 100 ppb Hg (Hg(NO 3 ) 2 ) sorption on 0.1 g Philips Mine tailings (2.1).....................................................................................................57

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iv Table A.4: 100 ppb Hg (Hg(NO 3 ) 2 ) sorption on 0.1 g Philips Mine tailings (2.2).....................................................................................................58 Table A.5: 100 ppb Hg (Hg(NO 3 ) 2 ) sorption on 0.1 g Kemiron (3.1)...............................59 Table A.6: 100 ppb Hg (Hg(NO 3 ) 2 ) sorption on 0.1 g Kemiron (3.2)...............................60 Table A.7: 100 ppb Hg (Hg(NO 3 ) 2 ) sorption on 0.1 g Kemiron (3.3)...............................60 Table A.8: 1,000 ppb Hg (Hg(NO 3 ) 2 ) sorption on 0.1 g Kemiron (4.1)............................61 Table A.9: 1,000 ppb Hg (HgCl 2 ) sorption on 0.1 g Pakera Creek (5.1)...........................62 Table A.10: 1,000 ppb Hg (HgCl 2 ) sorption on 0.1 g Philips Mine (5.2)........................62 Table A.11: 1,000 ppb Hg (HgCl 2 ) sorption on 0.1 g Kemiron (5.3)................................63 Table A.12: EDS quantifi cation (Arakaka Creek).............................................................64 Table A.13: EDS quantification (Kemiron).......................................................................64 Table A.14: EDS quantifi cation (Philips Mine)...............................................................64 Table A.15: EDS quantifi cation (Pakera Creek)................................................................65 Table A.16: EDS quantificat ion (Pakera Creek (2))..........................................................65

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v LIST OF FIGURES Figure 2.1: (A) Historical trend in nominal and real gold price = 100*(nominal average annual gold price/ averag e annual US CPI (all items urban consumers, 1982-1984=100). 2006 averaged from January to May). (B) Estimated global mercury use in the world in 2000 for a total of 3,386 metric tons ..............................................................................................6 Figure 2.2: Some of the transformations involved in the cycling of mercury ....................9 Figure 2.3: Depiction of the solid-wate r interface and sorp tion interpretation.................11 Figure 2.4: Map of northern por tion of Guyana and test si te (Arakaka) plus sites where previous studies have been published.................................................14 Figure 3.1: Speciation of 1E-5 M Hg 2+ .............................................................................24 Figure 3.2: Speciation of 5E-4 M Hg 2+ .............................................................................24 Figure 3.3: Speciation of 5E-4 M Hg 2+ with 0.001M Cl-.................................................25 Figure 4.1: SEM images of Kemiron for particles up to 38 m in diameter....................30 Figure 4.2: SEM image of Pakera Creek particles up to 38 m in diameter ....................30 Figure 4.3: SEM image of Philips Mine for particles up to 38 m in diameter...............30 Figure 4.4: EDS spectra and chemical qua ntification table for Philips Mine tailings..............................................................................................................31

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vi Figure 4.5: EDS spectra and chemical quantification for Pakera Creek............................31 Figure 4.6: EDS spectra and chemi cal quantification for Kemiron...................................32 Figure 4.7: XRD spectra for Philips Mine tailings...........................................................33 Figure 4.8: XRD spectra for Kemiron..............................................................................33 Figure 4.9: Sediment samples (Kemiron, Pakera Creek, and Philips Mine)....................34 Figure 4.10: Typical standards curve for THg analysis using CVAAS ............................35 Figure 4.11: Hg sorption to 0.5 g/L Kemiron....................................................................37 Figure 4.12: Hg sorption to 0.5 g/L Pakera Creek sediment.............................................37 Figure 4.13: Hg sorption to 0.5 g/L Philips Mine tailings................................................38 Figure 4.14: Hg sorption to 0.5 g/L of soil for 1,000 ppb Hg (from HgCl 2 ).....................39 Figure 4.15: Hg sorption to 0.5 g/L of soil for 1,000 ppb Hg (from HgCl 2 and Hg(NO 3 ) 2 ).........................................................................39

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vii GOLD MINING IN A TROPICAL RAINFOREST: MERCURY SORPTION TO SOILS IN THE MINING REGION OF ARAKAKAMATTHEW'S RIDGE, GUYANA Joniqua Aja Howard ABSTRACT Gold mining by artisinal (small-medium scal e) miners causes an immense amount of damage to the environment (i.e. soil er osion, mobilization of heavy metals, etc.). 1, 2 One of the most popular go ld mining techniques employed by ar tisinal miners in Guyana is mercury amalgamation. During the amalga mation process approximately 300 metric tons/yr 11, 12 of mercury is used. Mercury once in the environment can be transported through the air, soil, and wate r column. It is estimated that 90-99% of total mercury (THg) is associated with the sediment. An understanding of the geochemical conditions that affect the fate of merc ury in soils, which can act as potential sinks or sources for mercury, can provide solutions for redu ced environmental impacts of mercury contamination. Local Guyanese agencies have become concer ned with the quality of the water, soil, biota, and human impact in remote locations in the interior of Guyana. Therefore, soil samples were collected from two local mines in Guyanas Arakaka-Mathews Ridge area. Two soil samples (Pakera Creek and Philips Mine) and a commercially available ironoxide sorbent, Kemiron, underwent CVAA S, BET surface area analysis, electron dispersion spectroscopy, and x-ray diffractometr y. THg concentrations for recovered soil samples were approximately 300 ng/kg. In addition, samples were subjected to batch equilibrium sorption studies as a function of pH and mercury speci es/concentration added

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viii as Hg(NO 3 ) 2 and HgCl 2 All samples showed significant amounts of sorption between pH 3-9 for 100-1,000 ppb Hg added as Hg(NO 3 ) 2 When HgCl 2 .was added to the batch reactor containing Kemiron, an iron-oxide surface, the adsorption behavior of Hg 2+ decreased. Philips Mine solids, characterized as silicon dioxide by BET, had the lowest surface area (4 m 2 /g) and sorption when added as Hg(NO 3 ) 2 and HgCl 2 On the other hand, Kemiron and Pakera Creek displayed si milar sorption behaviors with high sorption across all pH ranges. This may be due to similar chemistry and larger surface areas. Surface loadings were 200 mg/kg and 2,000 mg /kg for experiments with 100 ppb Hg and 1,000 ppb Hg, respectively. Further analysis is required to identify the binding mechanisms between mercury and samples as well as the role of organic matter content on samples.

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CHAPTER 1: INTRODUCTION 1.1 Motivation and Research Objectives Mercury pollution due to gold mining has b een widely studied in the Amazon River Basin 1 which includes Brazil, Venezuela and the Guianas. Most of the mercury pollution studies have been conducted in Brazil with a very limited amount of research coming out of the much smaller Guyana (Britis h Guyana). In Guyana there has been an increase in mercury loading in the environmen t and a significant expansion in the number of permits held by artisinal (smalland me dium-scale placer deposit mines) that utilize mercury for gold extraction 2 Not surprisingly, local agencies like the Guyana Environmental Protection Agency and the World Wildlife Federation Guianas 3 have become progressively concerned with the qual ity of the water, soil, biota, and human impact in these particular mining areas that are remotely located in the interior of Guyana. An opportunity arose in May 2005 to accompany a team of investigators into two mining districts in Guyana (Arakaka and Mathews Ridge) under a WWF sponsored project. From that visit, the Trotz research laboratory at USF obtai ned soil samples from the area and pursued further studies on thos e samples. The WWF study also included hair, water and fish samples, however, thes e results remain unavailable as the local agency, the Institute of Applied Science a nd Technology, has not completed the research as of June 2006. The main objective of this research was to determine the sorptive capabilities of the Guyanese soils located close to small-medium scale-mining operations in the Arakaka and Mathews Ridge region. 1

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These soils can act as potential sinks or sources for mercury a nd an understanding of geochemical conditions that affect the fate of mercury can inform solutions for reduced environmental impacts of mercury c ontamination in mining activities. 1.2 Scope of Work and Approach A general overview of the work conducted in this research includes the evaluation of soil samples collected from Guyanas Mathews Ridge and Arakaka mi ning districts by BET surface area analysis, electron dispersion spectroscopy, and X-ray diffractometry for soil characterization. In addition to soil digesti on for total mercury cont ent, batch equilibrium studies were conducted to understand inorganic mercury sorption on the soils from Guyana and a commercially available iron oxide sorbent, Kemiron. Mercury quantification was done usi ng cold-vapor atomic absorption spectroscopy (CVAAS). These batch equilibrium sorption studies were evaluated as a function of pH and mercury concentration and mercury species (HgCl2 or Hg(NO3)2). Sorption studies assessed the ability of sediment to uptake merc ury concentrations of 100, 200, and 1,000 g/L. This thesis is arranged according to the following format: Chapter 2, Background. The background describes the mining environment in Guyana and discusses mercur y chemistry and research. Chapter 3, Materials and Methods. This section provides information on the materials used and experimental and analyt ical methods used for the work done in this thesis. Chapter 4, Results and Discussion. This sec tion presents and discusses the results of the experimental data. Chapter 5, Conclusion. The last section summarizes the research findings and makes recommendations for future research. 2

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CHAPTER 2: BACKGROUND 2.1 Introduction This chapter provides an overview of mercury pollution and how it relates to small scale gold mining operations in Guyana. Also review ed are mercury transformations in aquatic systems, health impacts, and the laws/r egulations governing the usage of mercury. 2.2 Mercury and its Health Effects Located on the periodic table as element num ber 80, mercury is a transition metal which exists at room temperatur e as liquid silver, known in Latin as hydragyrum. It is both a natural (e.g. volcanoes) and anthropogenic (e .g. mined ore) contaminant that causes deleterious human health effects includi ng impaired mental function, neurological disorders and kidney damage. It is a tran sition metal commonly f ound in three oxidation states (Hg(0), Hg(I), and Hg(II)) and is unique because its elemental state can vaporize at room temperature. Mercury can transform into methylmercury, the most toxic form known. Bioaccumulation and biomagnification of me thyl mercury occurs to a relatively high extent in aquatic systems 4-6 making fish consumption th e leading route of human exposure. As a result, United States Environmental Protection Agency (USEPA) recommended surface and drinking water limits are 12 ng/L and 2000 ng/L total inorganic mercury, respectively. Table 2.1 lists some guidelines/regulatory limits currently in effect for mercury. 3

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Unlike xenobiotics, mercury is found natura lly in the environment and does not degrade over time, but rather bioaccumulates and biomagnifies. Mercury bioaccumulation usually occurs in the fatty ti ssues of fish and is largely magnified in large predatory species such as salmon, shark, and king mack erel. According to the 2001 USEPA Fish Advisory warning, about 90% -100% of adult fish contain methylmercury, which accumulates in the fish muscle bound to prot eins. In Minamata, Japan over 3,000 people suffered from physical deformities, emotional di sorders, and oftentimes death due to the Chisso (Nitrogen) Corporations release of mercury into the Minamata Bay. The Chisso Corporation, a chemical manufacturing plant, released approximately 27 tons of mercury-laced waste into Minamata Bay from 1932 to 1968 where the local diet included the daily consumption of fish from the bay. As a result of excessive consumption of mercury-laced fish, residents began to deve lop signs of methylmercury poisoning, which became known as Minamata Disease. Table 2.1: Current regulatory limits a nd guidelines for mercury set by the US Environmental Protection Agency and the World Health Organization. USEPA WHO Drinking Water MCL ( g/L inorganic Hg) [4] 2 6 7 Recommended Surface Water (ng/L) 12 Permissible Hair ( g/g) 11.1 10-20 8 Urine ( g/g) below 10 Fish ( g/g) dry weight (fi sh-type dependent) 0.5* 2.5 7 *Same for USFDA According to the EPA and WHO, consumption of fish containing methyl-mercury should be limited to an intake of less than 1 ng/g a nd based on three factors: (1) fish size and type, (2) regular dietary intake, and (3) loca tion. The agencies reco mmend that pregnant woman and children reduce their in take of mercury-laced fish due to mercurys ability to be a neurotoxin. 4

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2.3 Mercury and its Uses Various physical, chemical and biological processes influence mercury speciation and transfer between soil, water, and air and atmo spheric deposition has been identified as the main route of aquatic mercury contamination in non-mining areas of temperate and cold regions where the bulk of scientific research has been conducted to date. Difficulties still remain in understanding global inputs to loca lized systems due to lack of data and understanding of complex processes govern ing mercury transformation and emission 9, 10 In 1995, estimated global anthropogenic contribu tions to atmospheric mercury emissions were 2,200 metric tons/yr with power plants being the la rgest contributor 11 and artisinal gold mining next with a reported 300 metric tons/yr 11, 12 In terms of use, artisinal gold and silver mining use nearly 20% of the 3,386 metric tons of mercury produced per year; batteries and chlor-alkali pro cesses account for 32% and 24% 13 (Figure 2.1). There is great variation on these estimates because of difficulties with acc ounting and lack of enforcement and regulations in some countries Figure 2.1 depicts the historical trend on the price of gold and distribu tion for various processes. Artisinal gold mining, also referred to as smallto mediumscale mining, describes mines that use extremely simple (mercury us ed as an amalgam with no proper processes regulating releases to the envi ronment) methods for gold reco very from various sizes of land throughout the world. Mercury has been used for centuries to recover gold and recent mining activities depend even more h eavily on it since most gold is now found in the very fine fractions of ore. The popular ity of mercury use in artisinal mining derives from its affordability, availabi lity, simplicity of use and lack of regulations governing use and disposal 14 These mines employ an estimated 11.5 to 13.2 million people either directly or indirectly, in 55 different countries 15 These numbers and the use of mercury will likely increase as gold prices continue to rise and other alternatives for livelihood and cleaner, affordable processes are not de veloped. China and Indonesia account for the bulk of mercury emissions from gold mining wh ilst approximately 10 -30 tons per year come from countries like Brazil and Venezuela 16 The tropical rainforests in the Amazon 5

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represent one of the worlds most biodiverse environments that is currently under threat from artisinal gold mining, defore station and industrialization. Figure 2.1: (A) Historical trend in nominal ( www.goldprices.com/Goldhistory.htm accessed 7/15/06) and real gold price = 100*(no minal average annual gold price/ average annual US CPI (all items urban cons umers, 1982-1984=100). 2006 averaged from January to May) 17 (B) Estimated global mercury use in the world in 2000 for a total of 3,386 metric tons 13 2.4 Impacts of Artisinal Gold Mining in South America The typical process used in ar tisinal mines begins with hydrau lic crushing of ore. The ore is then passed over a sluice box containing a mat to trap gold particles, which are then recovered by mercury in an amalgam. The am algam is heated to vaporize the mercury to recover gold. Though retorts exist for capturi ng mercury, they are not widely used by miners. The bulk of studies to date have been conducted in Brazil where mercury releases from deforestation and industrial ization compound the difficulties in estimating individual sources. Only recently has more research been done in French Guiana, Suriname and Guyana, which have significantl y less inputs from deforestation. Tables 2.2 and 2.3 show some of the sediment, soil and water concentrations found in the literature. 6

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High levels of mercury in indigenous populat ions of the Amazon basin in Brazil and Guyana have been reported 18 and linked to the consumption of fish, their primary protein 19 With the exception of disaster areas, hair mercury concentrations of vulnerable groups (women of reproductive age) in the Am azon are amongst the highest in the world 18 Table 2.2: Mercury concentrations in sediment and water samples from different parts of the world. Sediment Unfiltered Water Location Hg 20, 21 (ng/g) Methyl Hg (ng/g) Hg (ng/L) Methyl Hg (ng/L) Artisinal Au mines, Guyana* 22 Artisinal Au mines, Suriname 23 mine wastes streams below mines uncontaminated baselines Amazon basin 24-26 streams affected by mining upstream from mining Antartica streams and lakes Slovenia Hg mine 27 streams affected by mining upstream from mining 28 Worldwide background rivers and lakes 5-1200 5.5-200 110-150 14-48 24-406 67-93 1-219 <0.02-0.83 1.2-1.4 0.03-0.08 0.07-1.9 <1 0.49 11-930 6.4-10 2.9-33 2.2-2.6 0.27-1.9 18-322 <3 0.1-3.5 0.05-3.8 0.08-0.28 0.2-0.6 0.019-0.33 18-60 0.6 *samples collected for this study in May 2005. Other indigenous populations of the region, e .g. the Maroons in Suriname, also showed high levels of mercury in urine, which wa s correlated with proximity to mining activity 29 Studies in Brazil, Suriname, and French Guia na show that piscivorous fish have the highest mercury concentrations 30-33 and that concentrations increase as a function of rivers potentially affected by gold mining or industrial sites 31, 33 31 In Suriname, researchers found that increased turbidity due to mi ning activities result ed in a layer of finer particles (< 100 m) on river sediments which may contribute to negative effects on local fish populations 34 The turbidity in rivers close to artisinal gold mines in Guyana and Suriname was also linked to higher mercury concentrations 22, 34 In Guyana, higher mercury concentrations were found downstream from mining, but researchers could not tell whether mercury contamination was cau sed by current amalgamation use or whether 7

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it is actually mobilized from the ore itself 2, 22 Whilst these studies provide vital information on the extent of contaminati on and the form of contamination based on spectroscopic or sequential leach analysis, they provide limited information on the lability, reactivity, and bioavail ability of the mercury found. Table 2.3: Historical background total mercury concentrations. 2 Hg Concentrations within various media in mining locations within the humid tropics of South America Location/media Hg range Reference Channel sediments (ng/kg) Global background 70 (mean) Turekian, 1971 Pocon area, Brazil 23-198 Von Tmpling et al., 1995 Madiera River, Brazil 50-280 Pfeiffer et al., 1991 Madiera River, Brazil 30-350 Malm et al., 1990 Mazaruni River (Bartica), Guyana 77 (mean) Miller and Lechler, 2003 Essequibo River (Bartica), Guyana 42 (mean) Miller and Lechler, 2003 Soils (ng/kg) (*Ferralitic flood plain soils*) Background 20-50 Pierce et al., 1970 French Guiana 122-318 Rouletand Lucotte, 1995 Madiera River, Brazil 27-54 Malm et al., 1990 Madiera River, Brazil 30-180 Pfeiffer et al., 1991 Madiera River, Brazil 232-406 Lechler et al., 2000 Mazaruni River Basin (Bartica), Guyana 5-83 Miller and Lechler, 2003 Essequibo River Basin (Bartica), Guya na 44-228 Miller and Lechler, 2003 Water (ng L-1) Global Background 1-3 Gustin et al., 1994 Pocon area, Brazil <0.040b Lacerda et al.,1990 Madeira River, Brazil <40-9970b Malm et al., 1990 Madiera River, Brazil 20.0-510 Pfeiffer et al., 1991 b prior to the use of ultraclean laboratory procedures 2.5 Mercury Fate in the Aquatic Environment Various chemical (e.g. sorption, precipitation, photoinduced volatilizatio n) and biological (methylation or demethylation) processes infl uence the speciation of mercury in aquatic systems and extensive research has been done using both model and real conditions to understand them and the few examples given next just barely capture the complexities. Some of these processes are depicted in Figur e 2.2 and are discussed further in the next few paragraphs. Gaseous mercury compounds in the atmosphere deposit into the 8

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hydrosphere by precipitation or wet deposition (rain, snow, sleet, hail, or mist), particulate deposition and vapor adsorption (dry deposition), re sulting in increased levels of mercury. Once in the water compartm ent, mercury undergoes biogeochemical and photo-oxidation transformation. Mercury is distributed between chemical species including inorganic divalent mercury (II ) and organic mercury (methyl-mercury CH3Hg). The dominant species include HgCl2, HgCl4 2-, Hg2+, Hg, and Hg species sorbed onto mineral oxides, and organomercury species 35 Mercury also forms solid HgS(s) which is usually, but not always, found under re ducing environments (either in sediment or in biofilms in water column). Wate Hg0 (g) Algae BacteriaCH3H g H g( II Bacteria Hg(II)particle MeHgparticle Hgcolloi MeHgcolloi Air Hg0 (g) Hg(II) Sunlight Sediment CH3Hg+Hg(II) Bacteria HgS Phytoplankton Fish Zooplankton Figure 2.2: Some of the transformations involved in the cy cling of mercury 36 2.5.1 Mercury Sorption According to Lindsey 37 surface sediments in aquifers, lakes, and rivers contain metals in particular iron and aluminum as well as sili ca which represent the most abundant mineral oxides (Table 2.4). Mineral oxides play an im portant role in the sp eciation of mercury. Mineral oxides (e.g. iron and aluminum oxide s like goethite and gibbsite respectively) form amphoteric surface groups when in cont act with water. By definition, amphoteric groups can have positive, negative or neut ral charges along the surface/water interface 9

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and can accept or lose protons depending on th e pH of the solution. The behavior of the surface/water interface has been modeled using various surface complexation models. These empirical models include the Consta nt Capacitance (CC), Diffuse Double Layer (DD), CD-Music (CD-M), and triple layer (TLM ) models. Figure 2.3 uses the triple layer model to represent a mineral oxide surface showing the different types of surfaces charges. In this model, the o-plane, that cl osest to the mineral oxide surface, contains the amphoteric surface functional groups (XO-, XOH+, XOH), where X is the main ion to which the surface functional group is associated (e.g. Fe, Al, Si). Table 2.4: Content of various elements in soils 37 Metal Selected Average for soils ( ng/g) Common Range for Soils (ng/g) Al 71,000 10,000-300,000 Fe 38,000 7,000-550,000 Mn 600 20-3,000 Cu 30 2-100 Cr 100 1-1000 Cd 0.06 0.01-0.70 Zn 50 10-300 As 5 1.0-50 Ni 40 5-500 Ag 0.05 0.01-5 Pb 10 2-200 Hg 0.03 0.01-0.3 10

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Figure 2.3: Depiction of the solid-water interface and sorpti on interpretation. Therefore, under acidic conditions (or below the pKa of the mineral oxide) the overall number of positively charged surface site s would increase while under more alkaline conditions (above the pKa of the mineral oxide) the pos itive sites would diminish and vice versa would occur for negatively charged surface sites. Sorbing ions can lose their spheres of hydration and form a strong covalent bond with the surface in the o-plane (e.g. SOHg) or they can retain thei r spheres of hydration and form electrostatic bonds with the surface in the -plane (e.g. SO-..Hg2+). Ions in the diffuse layer and further away from the surface do not form any electrostatic or covalent bonds with the surface. Mercury (II) sorption to clays 38, 39 and mineral oxides of iron 40-44 aluminum 40, 42, 45 and silicon, some of the most common sediment constituents, 45-47 typically increases as a function of pH until it reaches a maxima then decreases in the higher pH regions. Methyl mercury sorption to goethite and kaolin, on the other hand was found to be much lower than inorganic Hg(II) sorption 39 The presence of ligands (e.g. chloride, sulfate, phosphate), other heavy metals (e.g. Ni(II), Pb (II)), and/or organic matter can influence mercury sorption to mineral oxide surfaces through various processes including 11

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competition for surface sites, changes in the su rface charge, formation of ternary surfaces and formation of more stable aqueous complexes 42, 44-48 In most sediments and natural waters, natu ral organic matter (NOM) can be found. NOM consists of carbon-based polyligands with va rious functional groups including carboxylic and thiols. Natural organic matter is known to form extremely strong complexes with mercury 49-51 thereby affecting desorption kinetic s from mineral oxides and even bioavailability 52, 53 Mineral oxide surfaces have b een functionalized with synthetic organic acid to increase the removal of mercury from aqueous solutions 54 These effects vary, however, depending on the biogeochemi cal conditions, the form of mercury, the site and the type of natural organic matte r (NOM). For example, fulvic acid, the hydrophilic fraction of NOM, increase d mercury sorption on goethite 41 but decreased sorption of both Hg(II) and methyl mercury from kaolin 39 NOM has different functional groups (e.g. carboxylic, phenolic, thiol) that play important roles in complexing mercury thereby causing a distribution of binding affinities 55, 56 Methylation and demethylation of mercury can occur via abiotic and microbial pathways 55 Researchers found that disso lved organic matter (DOM) influenced the abiotic, photoinduced methylation rates of mercury 57 Recent studies on mercury volatilization (to Hg(0)) found that the presence of NOM decreased volatilization in a queous solutions, but that mercury volatilization in real lake samples was significant in sunlight 58 Nanoparticles like iron oxides may play a major ro le in the transport of heavy metals in natural systems 59 Indeed, mercury concentrations downstream of Surinamese and Guyanese artisinal gold mines were positively correlated with turbidity and the finer fractions of suspended solids 22, 23 In fact, the majority of the mercury in the Guyanese samples, including depth profiles from unmine d ore, was associated with organic matter 22 This is not surprising given the high forest cover of this area. Ba sed on the literature review one would expect that the combin ation of high organic matter and suspended tailings to have a signifi cant effect on the processes governing mercury speciation and transport close to artisinal mines. 12

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2.6 Guyana Guyana (located on the north east coast of South Ameri ca and bordered by Brazil, Suriname and Venezuela) more closely resembles the English-speaking islands of the Caribbean with respect to history, language and culture than its South American neighbors. It is 214,970 km2 with a population of 765,283 the majority of whom reside in the coastal area and in poverty 60, 61 Many of Guyanas indigenous peoples (Amerindians) reside in the interior regions of the country and are dependent upon the natural environment for survival and econom ic resources. The main activities include manicole palm harvesting, logging, subsisten ce farming and activities associated with gold mining. Gold mining has been carri ed out in Guyana for over 100 years 60-63 The artisinal gold miners as well as gaimperos or pork knockers, illegal miners, use simple extraction techniques to quickly recover gold fr om placer (alluvial, colluvial, or elluvial) deposits such as land dredging, simple panni ng techniques, or amalgamation. In the Barima/Waini area of Region 1, where natives of the Arawak, Carib, and Warau Tribes reside, gold mining is carried out us ing the mercury amalgamation process 61 In Guyana, artisinal gold miners make up appr oximately 95% of all the miners while the remaining 5% are from large scale operations In the large-scale mining sector, miners use sophisticated equipment and cyanide (HCN) to extract gold from ore. In particular large scale companies such as OMAI Gold LTD. located in Region 8 utilizes cyanide. This method of extraction in mining is prefer red due to its higher yield of gold recovery than by the mercury amalgamation. However, due to the economical factors, limited technology, and easy availabili ty, small-scale miners use elemental mercury. 13

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Figure 2.4: Map of northern porti on of Guyana and test site (Arakaka) plus sites where previous studies 2,22 have been published. Figure 2.4 provides a map with the location of the site (Arakaka) plus two rivers for which the work of the Mazaruni 22 and Potero 22 have been published. Previous sampling for mercury in the Wai Wai district, at the mo st Southernly part of Guyana (not shown on Figure 2.4) revealed that the Amerindians there had the highest mercury hair concentrations of a range of Guyanese; fish concentrations were at WHO levels and they consumed five meals of fish per day 64 The WWF conducted st udies at the two gold mining sites in Guyana, Isseneru, located off of the Mazaruni River (1997, and 2000 65 ), Mathews Ridge (2005, data not processed as yet) and Arakaka (2005) Isseneru is an Amerindian village where over 90% of re sidents surveyed had greater than 14 g/g hair concentrations 65 (recommended USEPA permissible limit is 11 g/g). Singh 65, 66 reported that in a total of 168 fish samp les collected from Guyanas Kurupung and Isseneru areas the average concentration of mercury was 0.315 and 0.928 ng/g THg which exceeds the United States Food a nd Drug Administration guidelines limits of 0.5 ng/g (Table 2.1). In addition, Singh 66 correlated that elevated levels were due to average local dietary fish consumptions being 3-4 times per week as well as an association with 14

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mercury emanating from the natural environm ent. Apart from the extensive sediment sampling that was done along the Mazaruni and Potaro Rivers (indicated on Figure 2.4), further studies on human levels of contamin ation and fate of mercury and source of mercury are obviously needed in Guyana. Region 1, commonly known as the Northwest district, contains the towns of Arakaka and Mathews Ridge. Arakaka and Mathews Ri dge cover a land area of approximately 0.0084 km 2 This zone is geologically unde rlain by Precambrian rocks and a 0.001 km 2 section of a greenstone belt, an area underlain by metamorphosed volcanic and sedimentary rocks that contain chlorites, which borders the Iroma and Waini Rivers. Within Arakaka and Mathews Ridge there ar e or were several i ndustries that include manganese mining, diamond drilling, and gold mining 63 However, the dominant commerce today is gold mining. Arakaka is th e location of smalltomedium scale gold mining, and many miners and their families re side in the nearby town of Mathews Ridge. Residents within this area are de pendent on the natural water ways for the collection of fish, the principle source of protein. Drinking water sources include rain catchments, upstream springs, and river wate r. A survey done by the WWF-IAST team in 2005 identified the main sour ces of drinking water for Ar akaka as the Barima River and rain water. Mercury amalgamation is the process by which gold is extracted from ore via the usage of liquid mercury. With a legal mining workforce of roughly 11,000, Guyanas small scale mines use the following conventional gold mining process: (1) tree removal by logging, (2) land dredging or the use of hydraulic pressure to extract alluvial deposits, sediment that have been settled by water, (3) collection of ore placed on a sluice box for manual or mechanical gravitational agitation to settle gold depos its, (4) addition of Hg to the final concentrate (settled gold/ore deposits) th at has been shaken off of sluice mats ( It has been estimated that for every 1 kg of concentrate there is 14 grams of mercury required to form an amalgamate 67 or oftentimes approximately 30 grams of mercury is rubbed off on the final concentr ate retained on the sluice mats, 63 which is considered an 15

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illegal mining practice) ; (5) followed by a simple panning technique that washes excess sediment particles from ore to the final recovery process or roasting technique. Controversy does exist over whether mercur y contamination in the Amazon is due to burning of forests (the ferraltic soils ha ve high background mercury concentrations), mobilization of ore during mi ning, input of mercury from amalgamation processes or atmospheric deposition (with a nonlocalized mercury source). Atmospheric deposition has been identified as the main source of contamination, especi ally to remote areas of the world 68 In an attempt to model mercury con centrations in the Florida Everglades researchers found that atmospheric depositi on played a major role and noticed that mercury concentrations increased as a function of the amount of precipitation 9 Few studies have attempted to measure atmosphe ric deposition rates in the Amazonian region 69 and mercury concentrations downstream fr om mining have always been lower than upstream concentrations suggesting that atmo spheric deposition is not as significant as mining in these areas 21 The literature suggests that hi gher mercury concentrations are found downstream from artisinal mines and ar e directly linked with fines fractions 22, 34 16

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CHAPTER 3: MATERIALS AND METHODS 3.1 Introduction This chapter describes the materials and methods used in this thesis. It provides a detailed description of the experimental and analytical procedures used. 3.2 Materials 3.2.1 Glassware All glassware was washed with a 10% Liquinox detergent and rinsed with MilliQ water prior to soaking in 1 N NaOH. After one hour glassware was rinsed with MilliQ water and soaked in 10% HNO3 for an additional hour. The glassware was then rinsed multiple times with MilliQ water again and a llowed to air dry before usage. Polycarbonate reactor vessels and 10 mL polycarbonate centrifuge tubes were cleaned separately in a similar fashion as glassw are except a q-tip was used to scrub the containers free of remaining particulate matte r and acid and base concentrations were an order of magnitude lower. All rinse ex ercises were conducted three times before proceeding. 3.2.2 Reagents Mercury stock solutions were prepared in 100 mL glass volumetric flasks by dissolving Fisher Brand mercuric chlori de (M168-100) or mercuric ni trate in a 5% nitric acid solution. Concentrations of the Hg stock so lutions were measured against a calibration curve prepared using cold vapor atomic ab sorption of mercury st andards. Mercury 17

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calibration standards of 5, 10, 20, 30, 50, 70, and 100 ppb ( g/L) were made using a 10,000 ppm (mg/L) mercury stock solution in 5% nitric acid from CentriPrep that was diluted with 5% hydrochloric acid. All solutions (slurries and standards) had background elec trolyte concentrations of 0.1 N NaNO3 (Fisher Brand Certified ACS sodium nitrate crystals (S343-500)). The pH of slurry was varied using 0.1 N NaOH and 0.1 N HNO3. Both acid and base were standardized using standard methods. MilliQ water was used for all experiments and analysis. Acid and reductant solutions for cold vapor atomic absorption analysis were 5% HCl and 10% w/v stannous chloride (LabChem Inc LC25180-1), respectively. A bulk volume of 5% hydrochloric acid solutions were made w ith 32% w/v HCl (Fisher) and diluted with MilliQ water. Bulk solutions were stored in 1 L Nalgene high density polyethelyne bottles. 3.2.3 Kemiron /Sediments As described by Lindsey 37 soils in the environment are principally composed of aluminum, iron, or manganese oxides. Kemiron, a commercially available iron hydroxide material was used as a model iron oxide. Kemiron was obtained from Kemiron Company, U.S.A. It is highly porous with pore sizes ranging from 0.003 m to 328 m and a particle diameters of less than or equal to 600 m. This commercially available iron hydroxide material is commonly used as an absorbent in water and waste water treatment plants. Its principal benefit is to remove turbidity, reduce BOD/TOC/DBP, precipitate phosphates, conditi on sludge, reduce bacteria, re move heavy metals, as well as provide odor and corrosion control. 18

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Sediment samples were collected from the Ar akaka/Mathews Ridge region of Guyana in May 2005 by the Institute of Applied Scie nce and Technology (IAST) under a project funded by the Guyana WWF office. These sa mples were collected in HDPE containers and included the top 10 cm of sediment from the bottom of the water body tested. They were stored on ice until airlifte d to the IAST laboratory. On ce there they were air dried on filter paper, ground in a mortar and placed in doubly-bagged plastic storage bags. They were then shipped to the laboratory at USF where they were stored in a freezer until further use. The Philips Mine Tailings sa mple was collected by researchers at USF during the same time period from the tailings pond right under a sluice box at a mine in Arakaka. The sample was was taken from the surface and placed dir ectly into a sealed plastic storage bag. Kemiron and selected sediment samples were ground using a mortar and pestle and sieved using ASTM-E11, a stainless steel sieve of mesh size 400 (< 38 m). The sieved fraction less than 38 m was stored in doubly sealed plas tic storage bags in a sealed HDPE container. Size fractions of < 38 m were selected for batc h adsorption studies to decrease equilibration times. A five-point Braunauer, Emme tt, and Teller (BET) surface area analysis was done on Kemiron and selected soil samples using a Coulter SA2300 Surface Area Analyzer. The Kemir on and soils were dried at 80 oC for 18 hours and outgassed with helium at 80oC for 3 hours. XRD testing was based on particle size fractions of < 38 m while utilizing the back loading technique. 3.3 Analytical Procedures 3.3.1 Cold Vapor Atomic Adsorption The Varian 240FS-AAS coupled with a Vari an VGA77 attachment were used for the mercury cold vapor analysis technique also known as cold vapor atomic absorption spectroscopy (CVAAS). CVAAS analysis was used to determine total mercury concentrations, THg, in sediment samples. 19

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Mercury speciation was not conduc ted in this study. Before samples were analyzed using the manual CVAAS technique, all samp les were acidified to 0.5% HCl. Due to the analytical sensitivity when testi ng for trace levels of mercury extreme care was exercised. Therefore the capillaries for th e acid, reductant, and sample lines of the continuous vapor flow VGA77 were adjusted to an uptake rate of 1 mL/min, 1 mL/min, and 8 mL/min, respectively, and a mercury fl ow-through cell was attached to the Mark V burner head of the Varian 240FS. Optimal working conditions for the Varian 240FSAAS equipped with a VGA77 are outlined in Table 3.1. Table 3.1: Optimal working conditions for Hg determination in sediments using CVAAS. Parameters (Varian 240FS) Wavelength (nm) 253.7 Slit Width (nm) 0.5 Lamp Current 4 Integration time (s) 3 Vapor Generator (VGA 77) Acid uptake tube (mL/min) 1 Reductant uptake tube (mL/min) 1 Sample uptake tube (mL/min) 8 Argon* or Nitrogen Gas 99.99% pure Perimissible pressure range*** 43-57 psi Reagents Usage 5% Hydrochloric Acid, (from concentrated) Acid Line, Reagent Water*, Preservation* 20% (w/v) Stannous Chloride Reductant Line 5% Nitric Acid, concentrate d** Reagent water, preservation Notes: used in this study ** suggested (Varian, 1985) *** recommended pressure is 50 psi 20

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The calibration standards for the CVAAS t echnique were prepared from a 1,000 mg/L (10-6 g/L) stock solution manufactured by Centri Prep. Calibration standards of 5, 10, 20, 30, 50, 70, and 100 g/L were prepared fresh daily. The detection limit for Hg using the VGA77 and 240FS was 2 g/L (ppb). 3.3.2 Scanning Electron Microscopy/El ectron Dispersive Spectroscopy The Hitachi SEM Model 4105S was used to obs erve surface characteri stics of sediment samples. Working conditions for the SE M were between 20 to 17 KeV to reduce the amount of particle charging at the surface while under a high pressure vacuum of 90 torrs. Sample size fractions of < 38 m for Philips Mine Tailings and Kemiron were used. To prepare samples for analysis by SEM a small strip of carbon tape was adhered to the surface of the metal mounting plate. Next, soil samples were distributed evenly on to the surface of the carbon tape using a pa ir of metal tweezers th en inverted/lightly tapped to ensure that there were no lose part icles. Following procedures outlined in the SEM/EDS protocol distributed by the Material Science Research Center at the University of South Florida samples were carefully loaded into the SEM for analysis. 3.4 Batch Equilibrium Sorption Experiments The batch equilibrium experiment was setup by acid washing a 250-mL Nalgene polycarbonate reaction vessel with a screw cap and drilled holes fo r easy insertion of electrodes and sample ports. Background electrolyte solution of 0.1 N sodium nitrate (Fisher Brand Certified A.C.S. crystals, Ca t. # S343-500) and approximately 0.1 g of soil were mixed to form a slurry in the polycarbon ate vessel. Then th e initial pH of the slurry was analyzed, then the vessel was covered with parafilm and the slurry was allowed to equilibrate overnight at room temperature, 25 C. A Teflon ma gnetic stir bar was used to continuously stir th e slurry overnight. After equi libration, 8 mL of the slurry were pipetted into a 10-mL Nalg ene test tube with screw cap. This sample represented the initial background me rcury concentration ( Cblank) and the value was subtracted from all other concentrations found after mercur y addition. The stock mercury solution was 21

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then added to give a to tal added concentration, Cintial. The pH was adjusted to varying pH values of 3-10 8-mL samples collected at. pH adjustments with 0.1 N NaOH and 0.1 N HNO3. Once all samples were collected they were placed on an end-over-end shaker for 24 hours to equilibrate. Afte r the 24-hour batch reaction on the end over end Lab Quake Shaker, samples were analyzed for pH us ing an Orion Ross 8103BNU pH electrode and the Orion Duo 940A pH meter. Samples were then filtered using a 0.1 m disposable syringe filter, acidified to 0.5% hydrochloric, acid and analyzed for Hg by CVAAS. This represented the amount of mercury remaining in solution, Csolution. The amount of mercury removed during th e experiment was calculated from: % removed = [Cintial Cblank Csolution]/Cintial All waste materials were discarded in a double-sealed plastic storage bag following disposal instructions established by the Un iversity of South Floridas Environmental Health and Safety department. Equilibrium batch sorption experiments were done on three solid samples (Kemiron, Pakera Creek, and Philips Mine) at varying mercury concentrations of 100, 200, and 1,000 ppb (g/L). The following batch adsorption studies were conducted on solid samples: Table 3.2: Conditions used for batch ad sorption studies (1000 ppb Hg = 0.5E-5M). Sample [THg] (made from Hg(NO3)2) [THg] (made from HgCl2 Background Electrolyte Particle size ( m) Kemiron 100, 1000 ppb 1000 ppb 0.1N NaNO3 < 38 Philips Tailings 100 ppb, 200 ppb, 1000 ppb 1000 ppb 0.1N NaNO3 < 38 Pakera Creek 100 ppb, 1000 ppb 1000 ppb 0.1N NaNO3 -Experiments were also conducte d using solutions of Hg(NO3)2 and HgCl2 at 0.1 N NaNO3 in the absence of any solids. 22

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This was used to provide information on the amount of mercury that could be sorbed to the surface of the container and filter or phot ovolatilized during the experiment. These control experiments resulted in less than 5% removal of mercury. Most experiments were duplicated. Table 3.3 provides formation constants that we re used to determine Hg speciation under experimental conditions used in this thes is assuming that mercury was added as Hg2+ either as a Hg(NO3)2 or HgCl2. The two possible Hg(II) precipitates are Hg(OH)2(s) and HgCl2(s). Figures 3.1 and 3.2 show Hg(II) speciation if a total of 1E-5 M and 5E-4 M Hg was added to solution and Hg(OH)2(s) was allowed to precipitate. At 1E-5 M, all of the Hg2+ remains in solution and the dominant speci es between pH 4 and 10 is the uncharged Hg(OH)2. At 5E-4 M, the main species across pH 4 and 10 remains the same, however, the concentration is high enough for Hg(OH)2(s) precipitation. Hg spiked experiments in this thesis were all below 1E-5 M HgT therefore no precipitation was expected. Figure 3.3 shows Hg2+ speciation for a 1E-5 M total Hg concen tration in the pres ence of chloride where the dominant species are uncharged HgCl2 and HgOHCl up to around pH 8. These species dominate even more as chloride concentrations increase. Again, at the concentration of 1E-5 M, which was above experimental concentrations, no precipitates formed. Table 3.3: Formation constants for Hg2+species, Log Ks for ionic strength = 0. Equilibrium Reaction Log K HgP 2+P + OHP P -P P = Hg(OH)P +P P 10.6 HgP 2+P + 2OHP P -P = Hg(OH)B2B B B 21.8 HgP 2+P + 3OHP P -P = Hg(OH)B3PB B -P 20.9 HgP 2+P + ClPP P = HgClP +P P P 7.2 HgP 2+P + 2ClP-P = HgClB2B P P P B B 14.0 HgP 2+P + 3ClP-P = HgClP3-P P P P P 15.1 HgP 2+ P+ 4ClP-P P = HgClB P B 4PB 2-P 15.4 HgP 2+P + ClP-P + OHP P P P P = HgOHCl 18.1 HgP 2+P + 2OHP P -P = Hg(OH)B2(s)B B B 25.4 HgP 2+P + 2ClPP P = HgClB B 2(s)B B 14.21 P 23

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pC-pH Diagram for 1E-5 M HgT, Hg(OH)2(s)allowed to precipitate 0 5 10 15 20 25 30 024681 01 21 4pHpC Hg2+ HgOH+ Hg(OH)2 Hg(OH)3Hg2+Hg(OH)+Hg(OH)2Hg(OH)3 Figure 3.1: Speciation of 1E5 M Hg2+. pc-pH Diagram for 5E-4 M Hg2+. Hg(OH)2(s) allowed to precipitate0 5 10 15 20 25 30 024681 01 21 4pHpC Hg2+ HgOH+ Hg(OH)2 Hg(OH)3-Hg2+Hg(OH)+Hg(OH)2Hg(OH)3 Figure 3.2: Speciation of 5E-4 M Hg2+. 24

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pC-pH Diagram for 1E-5 M Hg2+ and 1E-3 M Cl-. Hg(OH)2(s) and HgCl2(s) allowed to precipitate. 0 5 10 15 20 25 30 35 024681 01 21 4pHpC Hg2+ HgCl+ HgCl2 HgCl3 HgCl4 Hg(OH)+ Hg(OH)2 Hg(OH)3HgOHClHgCl2Hg(OH)2HgOHCl Figure 3.3: Speciation of 1E-5M Hg2+ with 0.001M Cl-. 25

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CHAPTER 4: RESULTS AND DISCUSSION 4.1 Introduction Presented in this chapter are the experime ntal results for sediments from Guyanas Arakaka/Mathews Ridge mining region a nd model mineral oxide: total mercury concentrations by cold vapor atomic absorp tion analysis (CVAAS), surface area analysis, scanning electron microscopy (SEM), and elec tron dispersive spectroscopy (EDS/XRD). Results from equilibrium sorption experiments are also presented. 4.2 Total Mercury Analysis Total mercury sediment loadings were determined for all samples collected by Guyanas Institute of Applied Science during May 2005 for the Guyana WWF office. For total mercury concentrations, samples were se nt to a Tampa-based environmental wet chemistry laboratory, Advanced Environmen tal Labs (AEL). AEL digestion methods were based on Standard Methods 6971 for manual cold-vapor atomic adsorption analysis and the results are summarized in Table 4.1. Samples collected from the Arakaka area (Arakaka Creek #12, Arakaka Creek #3, and Arakaka Creek #8) exhibited total mercury co ncentrations close to global and local background concentrations of 70 ng/kg 70 and 42-77 ng/kg 2 respectively. Mercury levels in the remaining samples were within a range of 98-300 ng/kg which are similar to levels reported in the Brazilian Amazon mining areas (180-406 ng/kg ) 71, 72 26

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Elevated mercury levels in tropical rainfo rests are enhanced by temporal variations 73 ; organic content 35, 74 ; proportion of iron containing minerals 35 rainfall 35, 75 soil microbial activity 35, 76 and the extent of pollution. Mi ne waste sediment, Philips Mine, contained the highest total mercury concentr ations when compared to other samples collected from the area (excluding Water Sour ce for MWJ), which was consistent with mine tailings or waste results obtained from Gray et al. 77 Table 4.1: Total mercury concentrations in Mathew's Ridge/Arakaka area. THg in Region 2 of Guyana Sample ID THg (ng/g) Coordinates 78 (DMS) Elevation 78 (ft) Arakaka Creek #9 (Up Falls Top) 98 N 07 35.167 W060 01.183 29 Arakaka Creek #12 (Bamboo Creek) 41 N 07 34.799 W060 00.13 13 Arakaka Creek #13 73 N 07 34.762 W060 01.170 91 Arakaka Creek #8 (Down Manicora) 61 N 07 34.784 W060 00.186 145 Pakera Creek #5 200 Arakaka Creek #1 (Near River) 130 N 07 35.431 W059 58.714 63 Pakera Creek Reservoir #14 290 N 07 29.508 W060 08.044 21 Control Arakaka Creek #10 (Ravine Off Red Hill) 110 N 07 35.574 W059 59.378 62 Sediment Arakaka #4 180 N 07 34.761 W060 01.183 29 Water Source For MWJ (#1) 1200 ---Philips Tailings #1 300 ---Minab #7 200 N 07 29.956 W060 09.238 63 Soldier Pool #6 190 N 07 29.359 W060 11.120 54 Three of the samples with the highest concentrations were further analyzed to describe the possible fate/transport of mercury in the aquatic environment. Limited quantities of sediment, Water source for MWJ, prevented adsorption studies with this sample even though its mercury loadings were highest amongst the sampled sediments/soils. 27

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4.3 BET SEM/EDS and XRD BET, SEM imaging coupled with EDS/EDX sp ectra for individual samples of Kemiron, Pakera Creek #14, and Philips Tailings #1 were collected to determine particle morphology, surface area, and chemical info rmation. BET surface areas were 40 m2/g, 25.8 m2/g and 4 m2/g for Kemiron, Pakera Creek #14, and Philips Tailings #1, respectively. The low surface area of the ground Philips Mine tailings was expected since the material resembled an iron oxide -coated sand and sand usually has a very low surface area. Figures 4.1-4.3 show the SEM images of these three samples. The Kemiron surface appears porous with small (~2 m) particle deposits on the surface. The Pakera Creek and Kemiron samples both s howed surfaces consisting of particle agglomerations that were flaky in nature EDS/EDX and the corresponding SEM images in Figure 4.4 4.6 suggest that carbon we ight percentages are 45.76%, 40.38%, and 8.24 for Philips Mine, Pakera Creek, and Kemiron solids, respectively. High carbon contents for Philips Mine and Pakera Creek solids may be indicative of high organic matter content, which was expected given that the sa mpling location was in a tropical rainforest. This high organic matter content may contribut e to the flaky aggregate appearance seen in the Philips Mine and Pakera Creek samp les. The presence of organic matter may influence the adsorption of trace metals. Paktunc et al. 22 found high concentrations of organic matter in the sediments of the Potaro River in Guyana, even in unmined ore next to a mining pit. Kemiron, a commercially available iron oxide showed low C content, which was expected. It should be noted th at a carbon based tape was actually used to secure the sample on the holder for SEM a nd this may contribute to some background carbon concentrations being recorded for the Kemiron sample. In addition, the weight percentage of merc ury in the Kemiron sample was 1.76% where as Pakera Creek and Philips Mine sample s were 0.61% and 0.77%, respectively. This increased weight percent determined in the Kemiron sample may be due to contamination during the sample loading and prepping proce ss for the SEM/EDS analysis. The sample results for Pakera Creek (Figure 4.5) and Philips Mine (Figure 4.4) also show high iron and aluminum concentrations, suggesting the presence of iron and aluminum oxides. 28

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Physical characteristics and MRD PW 3060/20 XRD spectras when compared against the online database suggest that the mineralogy of soil samples collected from Philips Mine were predominately quartz with an iron oxide coating (Figur e 4.7). On the other hand, the Kemiron samples were composed of predominately iron hydroxide (Figure 4.8). 29

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Figure 4.1: SEM image of Kemir on for particles up to to 38 m in diameter. Figure 4.2: SEM image of Pakera Creek for particles up to to 38 m in diameter. Figure 4.3: SEM image of Philips Mine for particles up to to 38 m in diameter. 30

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Philips Tailings Elem Wt % At% C K 45.76 56.35 O K 40.53 37.47 Al K 4.32 2.37 Si K 5.91 3.11 S 0.01 0 Ba 0.42 0.05 Fe K 2.28 0.6 Hg L 0.77 0.06 Philips Tailings Elem Wt % At% C K 45.76 56.35 O K 40.53 37.47 Al K 4.32 2.37 Si K 5.91 3.11 S 0.01 0 Ba 0.42 0.05 Fe K 2.28 0.6 Hg L 0.77 0.06 Figure 4.4: EDS spectra and chemical quantif ication table for Philips Mine tailings. Figure 4.5: EDS spectra and chemical quantification for Pakera Creek. 31

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Figure 4.6: EDS spectra and chemi cal quantification for Kemiron. 32

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Figure 4.7: XRD spectra for Philips Mine tailings. Figure 4.8: XRD spectra for Kemiron. 33

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4.4 Batch Equilibrium Sorption Figure 4.9: Sediment samples (Kemir on, Pakera Creek, and Philips Mine). The transport and fate of mercury in the aque ous compartment is directly influenced by sorption to particle surfaces 79 Many batch equilibrium sorption experiments have been conducted for the sorption of mercury (I I) to various mineral oxide surfaces 46, 48 Batch equilibrium sorption studies performed in th is study are summarized in Table 4.2. Based on the speciation plots in Chapter 3, no solid precipitates should form at the concentrations used in the batch equilibrium sorption experiments. This was confirmed by testing the aqueous mercury concentration as a function of pH when no solid was present. Hence, the experiments using solid samples should reflect only adsorption mechanisms. 34

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Aqueous, 1000ppb Hg Standards Curvey = 0.0049x 0.0054 R2 = 0.99860 0.1 0.2 0.3 0.4 0.5 0.6 02 04 06 08 01 0 0Concentrationabsorbance Figure 4.10: Typical standards curve for THg analysis using CVAAS. New standards and standards curves were generated each time the instrument was run. A typical standard curve for total mercury c oncentrations remaining in solution is shown in Figure 4.10. The calibration was linear between 5 ppb and 100 ppb with less than 2% RSD for all readings. Figures 4.11 to 4.13 plot mercury sorption as a function of pH onto the three solid samples when mercury was added as Hg(NO3)2. For Kemiron and Pakera solids, mercury sorption remained high acr oss the pH region 3-9. Cationic sorption generally shows increased sorp tion with pH and though this ma y be true for these solid samples, the surface loading may still be t oo low to see that trend. For the case of Kemiron when mercury concentrations were increased to 1,000 ppb, close to 100% was still sorbed. This high concentration w ould actually mean a surface loading of 2000 mg/kg (g/g), which shows significant potential for Kemiron as a sorbent in remediation. Mercury sorption on Philips Mine tailings had the lowest of the three solids and could be reflective of the lower surface area (an orde r of magnitude lower than Kemiron). 35

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The Hg surface loadings on the Philips Mi ne tailings varied from 120 to 190 mg/kg (g/g) which was significantly higher than the results obtained from the field. The high capacity of these solids to sorb mercury indi cates their potential as sinks for mercury in the environment. Table 4.2: Summary of batch equilibrium sorption studies. Solid Solid Concentration (g/L) Hg THg (ppb) THg (M) Electrolyte Ionic Strength Amount sorbed/ amount of sediment at pH 7* None -HgCl2 1000 5E-6 NaNO3 0.1 -None -Hg(NO3)2 1000 5E-6 NaNO3 0.1 -Kemiron 0.5 HgCl2 1000 5E-6 NaNO3 0.1 6530.61 Kemiron 0.5 Hg(NO3)2 1000 5E-6 NaNO3 0.1 9843.58 Kemiron 0.5 Hg(NO3)2 100 5E-7 NaNO3 0.1 990.39 Pakera Creek 0.5 HgCl2 1000 5E-6 NaNO3 0.1 9671.18 Pakera Creek 0.5 Hg(NO3)2 100 5E-7 NaNO3 0.1 922.97 Philips Mine 0.5 HgCl2 1000 5E-6 NaNO3 0.1 8242.31 Philips Mine 0.5 Hg(NO3)2 100 5E-7 NaNO3 0.1 995.66 *Calculations are based on data results for pH 7 located in Appendix A. 36

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Figure 4.11: Hg sorption to 0.5 g/L Kemiron. Figure 4.12: Hg sorption to 0.5 g/L Pakera Creek sediment. 37

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Figure 4.13: Hg sorption to 0.5 g/L Philips Mine tailings. Since speciation of mercury changes in the presence of chloride ions, batch sorption equilibrium using sodium nitrate as a backgroun d electrolyte and mercuric chloride as the stock mercury concentration are outlined in Table 4.2. Samples prepared by the addition of mercuric chloride are shown in Figure 4.14. In the Kemiron samples depicted in Figure 4.15, so rption of mercury added as mercuric chloride is lower when compar ed to Kemiron samples prepared from mercuric nitrate. 38

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Figure 4.14: Hg sorption of 0.5 g/L of soil for 1,000 ppb Hg (from HgCl2). Hg sorption to 0.1g/200mL Kemiron For 1000ppb Hg, 0.1N NaNO30% 20% 40% 60% 80% 100% 234567891011pH% sorbed Hg added as HgCl2 Hg added as Hg(NO3)2 Figure 4.15: Hg Sorption of 0.5 g/L of soil for 1,000 ppb Hg (from HgCl 2 and Hg(NO 3 ) 2 ). 39

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Sorption characteristics for natural soil samples collected from Guyana which were prepared to a total mercury c oncentration of 1,000 ppb using HgCl2 stock solution indicate that in alkaline conditions (pH 8-10) sorption at the surfacemineral interface is relatively higher when compared to highly acidic conditions (pH 3-5) (Figure 4.14). However, when above pH 5 a distinct difference in sorption is observed for the commercially available iron-oxi de soil prepared with HgCl2 when compared to natural samples. It appears that sorption begins to d ecrease above pH 5 in the Kemiron samples. The behavior of mercury (II) at the solid/w ater interface by batch experiments has been studied widely 42, 46 Kim et al. 42 examined the effects of chloride and sulfate, common complexing ligands, to mineral sorbents of goethite (alpha-FeOOH), gamma-alumina (gamma-Al2O3), and bayerite (beta-Al(OH)3) by extended x-ray adsorption fine structure (EXAFS) spectroscopy. By measuring the uptak e of Hg (II) at pH 6 with an initial mercury concentration of 0.5 mM, Kim et al. 42 illustrated that the presence of chloride with concentrations of 10-5 to 10-2 M resulted in the reduction of mercury (II ) sorption. Bonnissel-Gissinger et al. 46 modeled the sorption of Hg (II) onto amorphous silica (Aerosil 200) and -FeOOH, goethite (Bayferrox 910), using various 68 pH conditions. The results by Bonnissel-Gissinger et al. 46 for the mineral sorbent, goethite, were consistent with data results from Kim et al 42 which suggests that th e presence of chloride limited the sorption of mercury to oxide surfaces due to the formation of stable metal ligand aqueous complexes that do not absor b. However, Bonnissel-Gissinger et al. 46 further suggested that the stru ctures of the oxides (Aerosil 200) and iron-oxides did not influence the sorptive capabilities of the samples. Wang et al. 68 examined the influence of chloride/mercury molar ratio and pH on the adsorption of mercury by poorly crystalline oxides of Al, Fe, Mn, and Si. Th ey reported that as the molar ratio of Cl/Hg increased, sorption decreased due to the formation of aqueous Hg-Cl complexes. The results from Figure 4.14 combined with the spectroscopic results presented in Figures 4.4 and 4.5, revealed a high organic content in the natural samples of Philips Mine tailings and Pakera Creek sediment: 45.76% and 40.38% by weight, respectively.. The organic portion of the natural sample s likely provided stronger complexing sites 40

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when compared to Kemiron (8.24% by weight ). According to the investigation of mercury distribution in waters of the coasta l lagoons of Rio de Ja neiro, Brazil, Lacerda and Goncalves 80 found that most dissolved mercur y was strongly bonded to refractory organic colloids. The Kemiron has the larg est surface area of the three solids tested which from a strictly sorption perspective would be expected to have the highest sorption capacity. The type of mineral oxide or the presence of other complexing ligands in the system resulted in the aqueous chloride complexes out-competing the Kemiron for mercury more than the real sediment samples. This was especially true above pH 5. The Philips Mine samples, which had a very low surface area also showed a strong binding capacity for mercury. These ta ilings also show significan t amounts of carbon and it is reasonable to assume that that carbon is in the form of natural organic matter since no carbonate minerals were identified by XRD. For the experiment with mercuric chloride, the natural organic matter appeared to play a major role in competing with aqueous mercury chloride complexes in the real sediment samples. Hence, in this tropical rainforest region, natural organic matter (NOM) may have play a significant role in mercury distributions. Fu rther studies are needed to understand the effect NOM has on mercury speciation/transf ormation reactions like abiotic photolysis. A 24-hour equilibration time was used for all experiments. Kinetic tests were not performed to validate this choice of equilibr ation period. Based on previous literature it is possible that longer equilibration times were needed for batch reactor experiments. 41

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CHAPTER 5: SUMMARY, CONCLUSION, & RECOMMENDATIONS FOR FUTURE WORK 5.1 Introduction The bioavailability, speciation, fate and transport of mercur y in the environment can be influenced by several natural and anthropoge nic activities like so il degassing, volcanic eruptions, mining, and industrial waste discharge. This secti on provides a summary of the experimental results, conclusions, an d recommendations for future work. 5.2 Summary of Results and Conclusions The main objectives for studies on the samples collected from Guyanas Mathews Ridge/Arakaka area were to provide the following: Determine total mercury concentra tions within the soil compartment o Total mercury concentrations of the collected soil/sediment samples were within the range of background me rcury loadings reported in the Amazonian mining districts (180-406 ng/kg 2, 22 ). One sample, MWJ, reported mercury loadings of 1200 ng/kg. The samples were ground and mixed prior to analysis and hence the results represent average loadings. Physical/Chemical characterization of soil samples o Philips Mine tailings and Pakera Creek sediment as well as a commercially available iron oxide, Kemiron, were subjected to BET surface area, XRD, SEM/EDS analysis The Philips Tailings had the lowest surface area (4 m2/g) whilst Kemiron had the highest (40 m2/g). SEM/EDS showed that the Philips Mi ne and Pakera Creek samples had 42

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high carbon content likely due to the presence of natural organic matter; however results may be inaccurate due to possible cross contamination of sampling due to loading procedures. XRD identified goethite as the main iron oxide phase present in Kemiron and SEM/EDS suggested that surface impurities may include mercury. The ground (less than 38 m) Kemiron sample showed a porous surface with crystalline particle deposits. Determine the potential for mercury sorption by soil samples based on batch reactor studies o Simultaneous acidification of ground and surface waters can lead to an increase in the mobility of mercury bound to soils and sediments 48 Similarly, soils and sediments can act as potential sinks for mercury in the environment. Batch adsorption studies of mercury on the Philips Mine tailings, Pakera Creek sediments a nd Kemiron showed significant sorption between pH 3 and 9 for conditions of 1 g/L solid and 100-1000 ppb Hg added as Hg(NO3)2. The Philips Mine tailings sample showed the lowest sorption and this was expected based on its low surface area compared with Kemiron or the Pakera Creek sample. The Pakera Creek and Kemiron samples showed similar behavior with high sorption across all pH ranges and surface loadings around 200 mg/kg for the 100 ppb Hg experiments and 2000 mg/kg for experiments with 1000 ppb Hg. o Adsorption behavior of Hg 2+ onto commercially available Kemiron, an iron-oxide surface, exhibited decrease d sorption patterns when mercuric chloride was added to the system compared to the addition of mercuric nitrate. 43

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5.3 Recommendations for Future Work Further identification of binding mechanisms between mercury and sediment samples is needed. This will include both sequential leaching techniques and further spectroscopic analysis and modeling. Study of the role of organic matter in mercury mobility. This will include quantification of organic ma tter content of soil/sediment samples as well as mercury partitioning to these phases. Kinetic tests should be conduc ted to predict the possibl e fate and transport of mercury (II) in soils. Future sampling in Guyana should be accomplished, especially in areas with higher mercury concentrations, and bette r correlations made with aqueous environmental parameters (pH, turbidity, alkalinity, TDS). Partnerships with the local community and non-governmental or ganizations should be sought to not only ensure continued access to the sampli ng sites and collected data, but also for the sustained development of solutions to the potential pollution problems. The use of Kemiron as a sorbent fo r mercury under various geochemical conditions including the presence of orga nic matter and other competing ions should be further explored. This could l ead to its further use as a remediation procedure. This research project examined the sorptive capabilities of sample Guyanese soils located close to small-to-medium scale mining operations in the Arakaka and Mathews Ridge region. These soils can act as potential sinks or sources for mercury and an understanding of geochemical conditions that affect the fate of mercury can inform solutions for reduced environmental impacts of mercury contamination. The motivation for the work lies in understa nding and reducing the envir onmental impact of mercury used in the mining sector. This region is populated by scattered communities with limited access to health care, analytical labs or centralized or coordinated drinking water treatment and distribution systems. As local organizations like th e Guyana WWF attempt to assess the extent of mercury contam ination and human exposure, a sustained 44

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relationship with studied communities is definitely needed. More importantly, multidisciplinary teams of researchers should be encouraged to further this work and provide opportunities that not only further scientific research, but provides both immediate and long term solutions to the lo cal community. In a politically fragile environment like Guyana, ways to form pa rtnerships with local communities and non governmental organizations are encouraged. 45

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REFERENCES 1. Lacerda, L. D.; Goncalves, G. O., Merc ury Distribution and Speciation in Waters of the Coastal Lagoons of Rio De Janeiro, Se Brazil. Marine Chemistry 2001, 76, (1-2), 47-58. 2. Miller, J. R.; Lechler, P. J.; Bridge G., Mercury Contamination of Alluvial Sediments within the Essequibo and Mazaruni River Basins, Guyana. Water Air and Soil Pollution 2003, 148, (1-4), 139-166. 3. WWF-Guianas Guianas Forests and Environmental Coneservation Program: Mercury Impact Assessment Project ; 2004. 4. Monson, B. A.; Brezonik, P. L., Seasonal Patterns of Mercury Species in Water and Plankton from Softwater La kes in Northeastern Minnesota. Biogeochemistry 1998, 40, (2-3), 147-162. 5. Watras, C. J.; Back, R. C.; Halvorsen, S.; Hudson, R. J. M.; Morrison, K. A.; Wente, S. P., Bioaccumulation of Merc ury in Pelagic Freshwater Food Webs. Science of the Total Environment 1998, 219, (2-3), 183-208. 6. Kim, J. P.; Burggraaf, S., Mercury Bioaccumulation in Rainbow Trout (Oncorhynchus Mykiss) and the Trout Food We b in Lakes Okareka, Okaro, Tarawera, Rotomahana and Rotorua, New Zealand. Water Air and Soil Pollution 1999, 115, (1-4), 535-546. 7. WHO Guidelins for Drinking-Water Quality: Incororating First Addendum. Volume 1, Recommenda tions. 3rd Edition. http://www.who.int/entity/water_sanitation_health/dwq/gdwq0506.pdf (7/5/06). 8. Klatutau-Guimaraes, M. D. N.; D'ascencao, R.; Caldart, F. A., Analysis of Genetic Susceptibility to Mercury Contamination Ev aluated through Molecular Biomarkers in at-Risk Amazon Amerindian Populations. Genetic Molecular Biology 2005, 28, (4), 827-832. 9. Atkeson, T.; Pollman, C.; Keeler, G. Integrating Atmospheric Mercury Deposition and Aquatic Cycling in the Flori da Everglades: An Approach for Conducting 46

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20. Charlet, L.; Roman-Ross, G.; Spadini, L.; Rumbach, G., Solid and Aqueous Mercury in Remote River Sediments (Lita ny River, French Guyana, South America). Journal De Physique IV 2003, 107, 281-284. 21. Spadini, L.; Charlet, L., Distributi on of Anthropogenic Mercury in French Guyana River Sediments Downstre am from Gold Mining Sites. Journal De Physique Iv 2003, 107, 1263-1266. 22. Paktunc, D.; Smith, D.; Couture, R., Mineralogical and Geochemical Characterization of Sediments and Suspende d Particulate Matter in Water from the Potaro River Area, Guyana: Implications for Mercury Sources. In Applied Mineralogy, Pecchio, M.; Andrade, F. R. D.; D'agostino, L. Z.; Kahn, H.; Sant'agostino, L. M.; Tassinari, M. M. M. L., Eds. ICAM-BR: Sao Paolo, 2004; pp 379-382. 23. Gray, J. E.; Labson, V. F.; Weaver, J. N.; Krabbenhoft, D. P., Mercury and Methylmercury Contamination Related to Artisanal Gold Mining, Suriname. Geophysical Research Letters 2002, 29, (23). 24. Nriagu, J. O.; Pfeiffer, W. C.; Malm, O.; Desouza, C. M. M.; Mierle, G., Mercury Pollution in Brazil. Nature 1992, 356, (6368), 389-389. 25. Maurice-Bourgoin, L.; Quiroga, I.; Guyot, J. L.; Malm, O., Mercury Pollution I the Upper Beni River, Amazonian Basin: Bolivia. Abio 1999, 28, 302-306. 26. Hylander, L. D.; Meili, M.; Oliveira, L. J.; Silva, E. D. E.; Guimaraes, J. R. D.; Araujo, D. M.; Neves, R. P.; Stachiw, R.; Barros, A. J. P.; Silva, G. D., Relationship of Mercury with Aluminum, Iron and Manganese Oxy-Hydroxides in Sediments from the Alto Pantanal, Brazil. Science of the Total Environment 2000, 260, (1-3), 97-107. 27. Hines, M. E.; Horvat, M.; Faganeli, J.; Bonzongo, J. C. J.; Barkay, T.; Major, E. B.; Scott, K. J.; Bailey, E. A.; Warwick, J. J.; Lyons, W. B., Mercury Biogeochemistry in the Idrija River, Slovenia, from above the Mine into the Gulf of Trieste. Environmental Research 2000, 83, (2), 129-139. 28. Kannan, K.; Smith, R. G.; Lee, R. F. ; Windom, H. L.; Heitmuller, P. T.; Macauley, J. M.; Summers, J. K., Distribution of Total Mercury and Methyl Mercury in Water, Sediment, and Fish from South Florida Estuaries. Archives of Environmental Contamination and Toxicology 1998, 34, (2), 109-118. 29. de Kom, J. F. M.; van der Voet, G. B. ; de Wolff, F. A., Mercury Exposure of Maroon Workers in the Small Scal e Gold Mining in Surinam. Environmental Research 1998, 77, (2), 91-97. 48

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30. Barbosa, A. C.; de Souza, J.; Dorea, J. G.; Jardim, W. F.; Fadini, P. S., Mercury Biomagnification in a Tropical Bl ack Water, Rio Negro, Brazil. Archives of Environmental Contamination and Toxicology 2003, 45, (2), 235-246. 31. Mol, J. H.; Ramlal, J. S.; Lietar, C.; Verloo, M., Mercury Contamination in Freshwater, Estuarine, and Marine Fishes in Relation to Small-Scale Gold Mining in Suriname, South America. Environmental Research 2001, 86, (2), 183-197. 32. Durrieu, G.; Maury-Brachet, R.; Boudou, A., Goldmining and Mercury Contamination of the Piscivorous Fish, H oplias Aimara in French Guiana (Amazon Basin). Ecotoxicology and Environmental Safety 2005, 60, (3), 315-323. 33. Mirlean, N.; Larned, S. T.; Nikora, V.; Ku tter, V. T., Mercury in Lakes and Lake Fishes on a Conservation -I ndustry Gradient in Brazil. Chemosphere 2005, 60, 226-236. 34. Mol, J. H.; Ouboter, P. E., Downstream Effects of Erosion from Small-Scale Gold Mining on the Instream Habitat and Fish Community of a Sm all Neotropical Rainforest Stream. Conservation Biology 2004, 18, (1), 201-214. 35. Fergusson, J. E., The Heavy Elements: Chemistr y, Environmental Impact and Health Effects Pergamon Press: 1990; p 429-524. 36. Gill, G. Biogeochemical Controls on Monomethyl Mercury Production in Aquatic Systems. http://gill.tamug.tamu.edu/OCNG647/Present ation/MethylMercuryProduction.ppt#262,1, Biogeochemical Controls on Monomethyl Mercury Pr oduction in Aquatic Systems. 37. Lindsay, W. L., Chemical Equilibria in Soils Wiley: 1979. 38. Sarkar, D.; Essington, M. E.; Misra, K. C., Adsorption of Mercury(Ii) by Kaolinite. Soil Sci Soc Am J 2000, 64, (6), 1968-1975. 39. de Diego, A.; Tseng, C. M.; Dimov, N.; Amouroux, D.; Donard, O. F. X., Adsorption of Aqueous Inorganic Mercury and Methylmercury on Suspended Kaolin: Influence of Sodium Chloride, Fulv ic Acid and Particle Content. Applied Organometallic Chemistry 2001, 15, (6), 490-498. 40. Kim, C. S.; Rytuba, J. J.; Brown, G. E., Exafs Study of Mercury(Ii) Sorption to Feand Al-(Hydr)Oxides I. Effects of Ph. Journal of Colloid and Interface Science 2004, 271, (1), 1-15. 49

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41. Backstrom, M.; Dario, M.; Karlsson, S.; Allard, B., Effects of a Fulvic Acid on the Adsorption of Mercury and Cadmium on Goethite. Science of the Total Environment 2003, 304, (1-3), 257-268. 42. Kim, C. S.; Rytuba, J.; Brown, G. E., Exafs Study of Mercury(Ii) Sorption to Feand Al-(Hydr)Oxides Ii. Effects of Chlo ride and Sulfate. Journal of Colloid and Interface Science 2004, 270, (1), 9-20. 43. Barrow, N. J.; Cox, V. C., The Effect s of Ph and Chloride Concentration on Mercury Sorption by Goethite. Journal of Soil Science 1992, 43, (2), 295-304. 44. Gunneriusson, L.; Sjoberg, S., Surface Complexation in the H+-Goethite ([Alpha]-Feooh)-Hg (Ii)-Chloride System. Journal of Colloid and Interface Science 1993, 156, (1), 121-128. 45. Sarkar, D.; Essington, M. E.; Misra, K. C ., Adsorption of Mercury(Ii) by Variable Charge Surfaces of Quartz and Gibbsite. Soil Science Society of America Journal 1999, 63, (6), 1626-1636. 46. Bonnissel-Gissinger, P.; Alnot, M.; Lickes J. P.; Ehrhardt, J. J.; Behra, P., Modeling the Adsorption of Me rcury(Ii) on (Hydr)Oxides Ii: Alpha-Feooh (Goethite) and Amorphous Silica. Journal of Colloid and Interface Science 1999, 215, (2), 313-322. 47. Mac Naughton, M. G.; James, R. O., Adsorption of Aqueous Mercury (Ii) Complexes at the Oxide/Water Interface Journal of Colloid and Interface Science 1974, Volume 47, (2), 431-440. 48. Tiffreau, C.; Lutzenkirchen, J.; Behra, P., Modeling the Adsorption of Mercury(II) on (Hydr)Oxides .1. Amor phous Iron-Oxide and Alpha-Quartz. Journal of Colloid and Interface Science 1995, 172, (1), 82-93. 49. Han, S. H.; Gill, G. A.; Lehman, R. D. ; Choe, K. Y., Complexation of Mercury by Dissolved Organic Matter in Surface Waters of Galveston Bay, Texas. Marine Chemistry 2006, 98, (2-4), 156-166. 50. Aijun, Y.; Changle, Q.; Shusen, M.; Reardon, E. J., Effects of Humus on the Environmental Activity of MineralBound Hg: Influence on Hg Volatility. Applied Geochemistry 2006, 21, (3), 446-454. 50

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51. Khwaja, A. R.; Bloom, P. R.; Brezonik, P. L., Binding Constants of Divalent Mercury (Hg2+) in Soil Humic Acids and Soil Organic Matter. Environmental Science & Technology 2006, 40, (3), 844-849. 52. Sjoblom, A.; Meili, M.; Sundbom, M., Th e Influence of Humic Substances on the Speciation and Bioavailability of Dissolved Mercury and Methylmercury, Measured as Uptake by Chaoborus Larvae and Loss by Volatilization. Science of the Total Environment 2000, 261, (1-3), 115-124. 53. Yin, Y. J.; Allen, H. E.; Huang, C. P.; Sparks, D. L.; Sanders, P. F., Kinetics of Mercury(II) Adsorption and Desorption on Soil. Environmental Science & Technology 1997, 31, (2), 496-503. 54. Tonle, I. K.; Ngameni, E.; Njopwouo, D.; Carteret, C.; Walcarius, A., Functionalization of Natural Smectite-Type Clays by Grafting with Organosilanes: Physico-Chemical Characterization and Application to Mercury(II) Uptake. Physical Chemistry Chemical Physics 2003, 5, (21), 4951-4961. 55. Benoit, J. M.; Gilmour, C. C.; Heyes, A.; Mason, R. P.; Miller, C. L., Geochemical and Biological Controls over Methylmercury Production and Degradation in Aquatic Ecosystems. In Biogeochemist ry of Environmenta lly Important Trace Elements Washington, D.C., 2002. 56. Drexel, R. T.; Haitzer, M.; Ryan, J. N. ; Aiken, G. R.; Nagy, K. L., Mercury(II) Sorption to Two Florida Ever glades Peats: Evidence for Strong and Weak Binding and Competition by Dissolved Organic Matter Released from the Peat. Environmental Science & Technology 2002, 36, (19), 4058-4064. 57. Siciliano, S. D.; O'Driscoll, N. J.; Tor don, R.; Hill, J.; Beauchamp, S.; Lean, D. R. S., Abiotic Production of Methylmercury by Solar Radiation. Environmental Science & Technology 2005, 39, (4), 1071-1077. 58. Amyot, M.; Mierle, G.; Lean, D. R. S.; McQueen, D. J., Sunlight-Induced Formation of Dissolved Gaseous Mercury in Lake Waters. Environmental Science & Technology 1994, 28, (13), 2366-2371. 59. Waychunas, G. A.; Kim, C. S.; Banfield, J. F., Nanoparticulate Iron Oxide Minerals in Soils and Sediments: Uni que Properties and Contaminant Scavenging Mechanisms. Journal of Nanoparticle Research 2005, 7, (4-5), 409-433. 60. Pelling, M., What Determines Vulnerability to Floods: A Case Study in Georgetown, Guyana. Environmental Problems 1997. 51

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61. Vereecke, J., United Nations Developm ent Programme, Country Office : Guyana, National Report on Indigenous Peoples and Development. In December 1994. 62. Vieira, R., Mercury-Free Gold Mining T echnologies: Possibilities for Adoption in the Guianas. In Press, Corrected Proof. 63. Vieira, R., Mercury-Free Gold Mining T echnologies: Possibilities for Adoption in the Guianas. Journal of Cleaner Production 2006, 14, (3-4), 448-454. 64. Coutoure, R., Personal Commnication. 1/13/2005. 65. Singh, D. J.; Rodrigues, M.; Best, W.; DBrowman, D.; Quik, J., Survey of Mercury Contamination in the Mazaruni Ri ver from Small Scale Mining Activity. In Environmental Studies Unit: 1997. 66. Singh, D.; Watson, C.; Mangal, S. Identification of the Sources and Assessment of the Levels of Mercury Contam ination in the Mazaruni Basin in Guyana, in Order to Recommend Mitigation Measures ; Institute of Applied Science and Technology 2001; pp 1-10. 67. Veiga, M. M., Mercury in Artisanal Go ld Mining in Latin America: Facts, Fantasies and Solutions. In UNIDO Expert Group Meeting, Vienna, 1997. 68. Wang, Q.; Kim, D.; Dionysiou, D. D.; Sori al, G. A.; Timberlake, D., Sources and Remediation for Mercury Contamination in Aquatic Systems--a Literature Review. Environmental Pollution 2004, 131, (2), 323-336. 69. Tessier, E.; Amouroux, D.; Grimaldi, M.; Stoichev, T.; Grimaldi, C.; Dutin, G.; Donard, O. F. X., Mercury Mobilization in Soil from a Rainfall Event in a Tropical Forest (French Guyana). Journal De Physique Iv 2003, 107, 1301-1304. 70. Applequi.Md; Turekian, K. K.; Katz, A., Distribution of Mercury in Sediments of New Haven (Conn) Harbor. Environmental Science & Technology 1972, 6, (13), 1123-&. 71. Lechler, P. J.; Miller, J. R.; Lacerda, L. D.; Vinson, D.; Bonzongo, J. C.; Lyons, W. B.; Warwick, J. J., Elevated Mercury Con centrations in Soils, Sediments, Water, and Fish of the Madeira River Basin, Brazilian Amazon: A Function of Natural Enrichments? Science Of The Total Environment 2000, 260, (1-3), 87-96. 52

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72. Pfeiffer, W. C.; Malm, O.; Souza, C. M. M.; Delacerda, L. D.; Silveira, E. G.; Bastos, W. R., Mercury in the Madeira River Ecosystem, Rondonia, Brazil. Forest Ecology And Management 1991, 38, (3-4), 239-245. 73. de Lacerda, L. D., Updating Global Hg Emissions from Small-Scale Gold Mining and Assessing Its Environmental Impacts. Environmental Geology 2003, 43, (3), 308314. 74. Dzombak, D. M.; Morel, F. M. M., Surface Complexation Modeling on Hydrous Ferric Oxide John Wiley & Sons: New York, NY, 1990. 75. Lacerda, L. D.; Paraquetti, H. H. M.; Rezende, C. E.; Silva, L. F. F.; Silva, E. V.; Marins, R. V.; Ribeiro, M. G., Mercury Con centrations in Bulk Atmospheric Deposition over the Coast of Rio De Janeiro, Southeast, Brazil. Journal Of The Brazilian Chemical Society 2002, 13, (2), 165-169. 76. Guimaraes, J. R. D.; Meili, M.; Malm, O. ; Brito, E. M. D., Hg Methylation in Sediments and Floating Meadows of a Tropical Lake in the Pantanal Floodplain, Brazil. Science Of The Total Environment 1998, 213, (1-3), 165-175. 77. Gray, J. E.; Hines, M. E.; Higueras, P. L.; Adatto, I.; Lasorsa, B., Mercury Speciation and Microbial Tran sformations in Mine Wastes, Stream Sediments, and Surface Waters at the Almaden Mining District, Spain. Environ. Sci. Technolo. 2004, 4285-4292. 78. Bera, S. Wwf Iast Mercury Impact Assessmen t Project-Region 1: Arakaka, Mathew's Ridge and Port Kaituma ; IAST: Georgetown, Guyana, June 10, 2005, 2005; pp 1-5. 79. Kim, C. S.; Rytuba, J. J.; Brown, G. E., Geological and Anthropogenic Factors Influencing Mercury Speciation in Mine Wastes: An Exafs Spectroscopy Study. Applied Geochemistry 2004, 19, (3), 379-393. 80. Lacerda, G. O. G. L. D., Mercury Dist ribution and Speciation in Waters of the Coastal Lagoons of Rio De Janerio, Se Brazil. Marine Chemistry 2001, (76), 47-58. 53

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APPENDICES 54

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Appendix A: Abridged Experimental Data Results Tabular report of the equilibrium sorption experiments discussed in Chapter 4. Data results have been grouped according to sample name then by the mercury stock solution (i.e. HgCl2 or Hg(NO3)2). Table A.1: 100 ppb Hg (Hg(NO 3 ) 2 ) sorption on 0.1 g Pakera Creek sediment (1.1). Experiment 1.1: 100 ppb Hg (Hg(NO3)2) Sorption on 0.1 g Pakera Creek Sediment Background electrolyte: 0.1 N sodium nitrate pH THg (ppb) % Hg Sorbed 3.68 5.11 95% 3.97 4.90 95% 5.26 2.11 98% 5.41 4.45 96% 5.63 3.13 97% 5.69 1.57 98% 5.84 0.63 99% 5.86 2.95 97% 6.01 4.72 95% 6.90 7.70 92% 7.31 4.11 96% 55

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Appendix A: (Continued) Table A.2: 100 ppb Hg (Hg(NO 3 ) 2 ) sorption on 0.1 g Pakera Creek sediment (1.2). Experiment 1.2: 100 ppb Hg Sorption on 0.1 g Pakera Creek Sediment Background electrolyte: 0.1 N sodium nitrate pH THg (ppb) % Hg Sorbed 3.10 5.47 90% 5.27 5.04 90% 6.02 5.51 89% 6.49 5.04 90% 6.70 6.66 88% 6.75 5.64 89% 6.91 5.57 89% 7.16 10.51 84% 7.40 1.06 84% 7.80 5.43 90% 9.34 5.28 90% 56

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Appendix A: (Continued) Table A.3: 100 ppb Hg (Hg(NO 3 ) 2 ) sorption on 0.1 g Philips Mine tailings (2.1). Experiment 2.1: 100 ppb Hg (Hg(NO3)2) Sorption on 0.1 g Philips Mine tailings Background electrolyte: 0.1 N sodium nitrate pH THg (ppb) % Hg Sorbed 3.10 7.83 92% 3.39 5.47 95% 3.54 6.33 94% 4.10 31.07 69% 4.52 34.95 65% 4.85 32.95 67% 5.51 9.47 91% 5.63 92.76 7% 5.79 12.90 87% 5.87 7.60 92% 7.38 4.97 95% 57

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Appendix A: (Continued) Table A.4: 100 ppb Hg (Hg(NO 3 ) 2 ) sorption on 0.1 g Philips Mine tailings (2.2). Experiment 2.2: 100 ppb Hg (Hg(NO3)2) Sorption on 0.1 g Philips Mine tailings Background electrolyte: 0.1 N sodium nitrate pH THg (ppb) % Hg Sorbed 3.57 0.72 89% 3.96 18.06 71% 6.34 7.55 76% 6.47 5.87 83% 7.30 0.75 71% 9.56 0.43 88% 58

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Appendix A: (Continued) Table A.5: 100 ppb Hg (Hg(NO 3 ) 2 ) sorption on 0.1 g Kemiron (3.1). Experiment 3.1: 100 ppb Hg (Hg(NO3)2) Sorption on 0.1 g Kemiron Background electrolyte: 0.1 N sodium nitrate pH THg (ppb) % Hg Sorbed 4.37 0.18 100% 4.71 0.10 100% 5.08 0.06 100% 5.39 0.10 100% 5.98 0.35 100% 6.58 0.35 100% 7.29 0.27 100% 7.44 0.30 100% 8.21 0.13 100% 59

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Appendix A: (Continued) Table A.6: 100 ppb Hg (Hg(NO 3 ) 2 ) sorption on 0.1 g Kemiron (3.2). Experiment 3.2: 100 ppb Hg (Hg(NO3)2) Sorption on 0.1 g Kemiron Background electrolyte: 0.1 N sodium nitrate pH THg (ppb) % Hg Sorbed 4.24 0.09 96% 5.49 0.11 96% 6.24 0.41 96% 6.93 0.19 96% 7.74 0.41 96% 9.03 0.39 96% Table A.7: 100 ppb Hg (Hg(NO 3 ) 2 ) sorption on 0.1 g Kemiron (3.3). Experiment 3.3: 100 ppb Hg (Hg(NO3)2) Sorption on 0.1 g Kemiron Background electrolyte: 0.1 N sodium nitrate pH THg (ppb) % Hg Sorbed 4.07 0.13 96% 5.07 1.76 96% 6.26 0.27 96% 7.38 0.40 96% 8.03 1.67 95% 60

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Appendix A: (Continued) Chapter 4.4: Equilibrium sorption experiment s. Kemiron; Hg Spike from mercuric nitrate with varied total mercury concentrations of 200 and 1,000 ppb. Table A.8: 1,000 ppb Hg (Hg(NO 3 ) 2 ) sorption on 0.1 g Kemiron (4.1). Experiment 4.1: 1000 ppb Hg (Hg(NO3)2)Sorption on 0.1 g Kemiron Background electrolyte: 0.1 N sodium nitrate pH THg (ppb) % Hg Sorbed 3.07 8.85 99% 3.66 10.26 99% 3.92 10.64 99% 4.53 11.68 99% 4.97 13.66 99% 5.99 14.70 99% 6.45 15.64 98% 7.95 16.77 98% 9.62 17.91 98% 9.92 18.38 98% 61

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Appendix A: (Continued) Chapter 4.4: Equilibrium sorption experime nts for all samples (Pakera Creek, Philips Tailings, and Kemiron); Hg spike from mercuric chloride with varied total mercury concentrations of 1,000ppb. Table A.9: 1,000 ppb Hg (HgCl 2 ) sorption on 0.1 g Pakera Creek (5.1). Experiment 5.1: 1,000 ppb Hg Sorption on 0.1 g Pakera Creek Background electrolyte: 0.1 N sodium nitrate pH THg (ppb) % Hg Sorbed 2.86 430.32 57% 3.4 390.38 61% 4.84 294.61 71% 6.85 32.88 97% 8.74 37.21 96% 5.57 80.96 92% 4.43 307.59 69% Table A.10: 1,000 ppb Hg (HgCl 2 ) sorption on 0.1 g Philips Mine (5.2). Experiment 5.2: 1,000 ppb Hg Sorption on 0.1 g Philips Mine tailings Background electrolyte: 0.1 N sodium nitrate pH THg (ppb) % Hg Sorbed 2.68 256.92 74% 4.6 241.06 76% 6.23 175.77 82% 5.36 233.27 77% 8.67 55.10 94% 8.88 55.38 94% 9.04 44.52 96% 62

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Appendix A: (Continued) Chapter 4.4: Equilibrium sorption experime nts for all samples (Pakera Creek, Philips Tailings, and Kemiron); Hg spike from mercuric chloride with varied total mercury concentrations of 1,000 ppb. Table A.11: 1,000 ppb Hg (HgCl 2 ) sorption on 0.1 g Kemiron (5.3). Experiment 5.3: 1000 ppb Hg Sorption on 0.1 g Kemiron Background electrolyte: 0.1 N sodium nitrate pH THg (ppb) % Hg Sorbed 2.84 356.36 64% 3.28 383.67 62% 4.44 380.88 62% 4.94 367.42 63% 5.46 302.80 70% 6.35 346.94 65% 8.51 462.04 54% 63

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Appendix A: (Continued) Chapter 4.3: EDS Quantification Results All electron dispersion graphic signals and quantification resu lts were taken at 25kV with a tilt of 30 and take-off of 36.31 at total counts of 100.0 seconds. Table A.12: EDS quantification Table A.13: EDS quantification (Arakaka Creek) (Kemiron) Arakaka Creek Kemiron <38 m Elem Wt % At% K-Ratio Elem Wt % At% K-Ratio C K 23.41 33.41 0.0398 C 8.24 16.29 0.0208 O K 44.23 47.39 0.1115 O 41.64 61.72 0.1699 F K 1.02 0.92 0.0015 Mg 3.44 3.36 0.0095 Al K 1.46 0.93 0.0092 Ca 0.44 0.26 0.0042 Si K 27.65 16.88 0.2069 Fe 42.12 17.9 0.3893 Fe K 1.29 0.4 0.0113 Hg 1.76 0.21 0.0127 HgL 0.95 0.08 0.0066 Pb 2.39 0.27 0.0169 Table A.14: EDS quantifi cation (Philips Mine) Philips Tailings Elem Wt % At% K-Ratio C K 44.79 55.87 1.0192 O K 39.14 36.66 1.0038 Al K 4.34 2.41 0.9382 Si K 7.6 4.05 0.9662 K K 0.15 0.06 0.912 Ca K 0.02 0.01 0.9357 Ti K 0.34 0.11 0.8588 Fe K 2.88 0.77 0.8585 Hg L 0.74 0.05 0.6569 64

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Appendix A: (Continued) Chapter 4.3: EDS Quantification Results All electron dispersion graphic signals and quantification resu lts were taken at 25kV with a tilt of 30 and take-off of 36.31 at total counts of 100.0 seconds. Table A.15: EDS quantification Table A.16: EDS quantification (Pakera Creek) (Pakera Creek (2)) Pakera Creek Pakera Creek Elem Wt % At% K-Ratio Elem Wt % At% K-Ratio C 22.2 32.48 0.0438 C 40.38 53.03 0.1123 O 45.93 50.44 0.1256 O 38 37.47 0.0843 Al 7.68 5.00 0.044 Fe 8.42 2.38 0.224 Si 15.25 9.54 0.0964 Al 4.58 2.68 0.0263 S 0.06 0.03 0.0004 Si 7.51 4.22 0.05 Cl 0.11 0.05 0.0008 K 0.22 0.09 0.002 K 0.53 0.24 0.0045 Ti 0.22 0.07 0.002 Ba 0.94 0.12 0.0079 Mn 0.05 0.02 0.0005 Mn 1.07 0.34 0.0093 Hg 0.61 0.05 0.0042 Fe 5.31 1.67 0.0468 Hg 0.93 0.08 0.0065 65