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Title:
Caves and karst: Research in speleology
Series Title:
Caves and Karst: Research in Speleology
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Cave Research Associates
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Cave Research Associates
Tumbling Creek Cave Foundation
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Language:
English

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Geology ( local )
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serial ( sobekcm )

## Notes

General Note:
Contents: The application of stable isotope studies to karst research: discussion / Alan D. Howard Barbara Y. Howard -- The application of stable isotope studies to karst research: reply / Russell S. Harmon. Cave Notes(vols. 1-8) and Caves and Karst: Research in Speleology(vols. 9-15) were published by Cave Research Associates from 1959-1973. In 1975, the Tumbling Creek Cave Foundation compiled complete sets of the journals in three volumes. The Foundation sells hardbound copies of the material to support its activities.
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Open Access - Permission by Publisher
Original Location:
Tumbling Creek Cave Foundation Collection
Original Version:
Vol. 14, no. 2 (1972)
General Note:

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University of South Florida Library
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University of South Florida
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Resource Identifier:
K26-01036 ( USFLDC DOI )
k26.1036 ( USFLDC Handle )
13301 ( karstportal - original NodeID )
0008-8625 ( ISSN )

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Karst Information Portal

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PAGE 1

, Resea[~h in, Speleology , Volume 14, Number ,2 , ; CONTENTS, :ALAN D, HOWAR.,D& BARBARA Y. HdwARD:'Th~ Application : of Stable Isotope Studies toKarst-Research: Discussion """",,,,,,,,,,:,,,,>, .. ,.'9 \. '. '. I" ,\ t RUSSELL 8: HARMQN' Th,cApplicationof S\abJe Isotope ,studies .,". to' Karst Research: Reply . '''''''''''', ....... : .. .. ..... """""',""" .... .... ........ 13 ",'. 'I' Mlicat,ion o(CANli; R~SIJARCR ASSOciATEiS

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,', ,_ \ ,j I c;;AVE RESEÂ£iRCH,AsSQCI4TES '( II Cave \R.e,seard1. Associjlte~ is a n~n~prQfit scientific and educarional insdtutloh incor)ota't~dI in 195p ~o further the study and pr,esetvatiop, d.f natural ewes. Re.s~ch projects and publications 6} tb~ organ~don ar~ s\l?po~(ed prima:~i1y.qyprivate contributions. All.silch cohtJ;ibmions a~et tn.dequcdbI~. I "I I' \ MembeJ;shjp iQ,' Chve R~search AssQcia(es' is open to persons 6f all ~tions who Cletnon,st(ate a PlUtl~la.t;lliiiter~sl and backg~o':lnd ih rhe.cave and 'kl1r~ sciences,and who' ,s,u1(BJ:t'jbe to .rhe cohse~ation pradtises eStab!islied by-the T'rusrees/ Perseus iliferestid in beq)mjqg. tp:embets' should wrire, thff S\cc,retatY }4r informatioa on membership. M~,eliaI19r phblica[i~b In' CAVES il,ND M1I.IT and CAV:B S7;VDIES is invited frorn the scientific community at large a~ wellias C.R.A.. members. 'Authers, shOuld follow q1~, i~r~uotioQS ,.fr~vid~a ~ere~~. 'II~ J'I, l' I ~ ' , ,. L. A. Payen , I' ,. INFO&M:AnONFOR AUTHORS" I I \.' ,. " Scope.;~ CAWES MfO' KARST conraios Â£e~ture artk1es, notes, discussions, ,news,' reviews, editorials aria annotated ~jbllogtaphi ... A"icles should coarein results of 'originlU wo~ i end ideas, and treit~ent sh"orild', be of ai'ore t,ban local interest. Mere .ceve descriptions. anC;) field trip accounrs are, l\Qt accepretL 'News nores are connned 'to siSJ:1Uicant CUt'r,ent eYen~sJ and reviews, and annotated bibliopapJt eptries should t1eat ma'ter~al DQt OVet 'wo )'eaJ;/ old. '. .' jl.' ,. ~ \ ('Continued 'on ba~ wide cpo",)

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CAVES AND KARST Research in Speleology Volume 14, No.2 ._-----------'-.:..-.....:-...:: Meech/ Aprtl 1972 THE APPLICATION OF STABLE ISOTOPE STUDIES TO KARST RESEARCH:!. DISCUSSION BY ALAN D. HOWARD' & BARBARAY HOWARD" Harmon (1971a; b) has suggested that the measurement of stable carbon isotope ratios of dissolved carbonates in karst groundwaters may help to determine the sources of dissolved ions and the history of the groundwater. We feel, however, that Harmon places 'insufficient emphasis upon the complexi?,; of the natural processes affecting the 13 C: J 2 C ratio (which is generally expressed as [j I C permil, or 0 /0 0 ; see HARMON J J 971 a, b). OUf discussion centers upon these complicating factors as well as some 'minor corrections to Harmon's papers. Corrections Several equations in the first paper by Harmon (197la) appear to be incorrect. Equations 12-14 require l11ultiflication of the term on the right-hand side containing the temperature by a factor of1 0 to give values corresponding to his Figure 3 and Tables 811. Harmon's Equation 25 should read: 8 13 C;Eo ;=:::; 013CC02(g) + (K~* K j 1) 10 3 Similarly, Ius Equation 24 should be corrected by replacing each of the fractionation factors Kr by (Kt-I] 10 3 When so corrected, these equations (derived from the definition of.8PC and Harmon's Equations 15-18) give the values of l}/,3C enrichment and depletion for HCD:'! ~ quoted by Harmon (1971 a: 26), using the K,!, values in his Table 12. Sources of carbon dioxide species in groundwater Harmon (1971a: 21) states that his Equations 5-7 imply that solution of limestone by carbonated water results in a quantity of dissolved carbonate species at-equilibrium contributed equally by a gas phase (the atmosphere or soil gasses) and by a solid carbonate source (limestone or dolomite). Pearson and Hanshaw (1970) make a similar assumption in a study. of groundwater in a Florida limestone aquifer. In fact, the situation is hot so simple; a unique value of the ratio of the arnount'of carbona te species in solution (H 2 C0 3 HC0 3 and C03 --') from gas and solid phase sources, respectively, is defined only in the case of closed-system equilibrium; that is, where the groundwater dissolving the limestone is not in contact with the gas phase with which it previously equilibrated (Case 5 of GARRELS &CHRlST (1965): 86-88). In closed-system equilibrium, the total quantity of dissolved carbon' dioxide species derived from the gas phase, mco 2g equaJs the sum of the molalities of the species con-taining carbon dioxide resulting from equilibration between the groundwater and the gas phase before its contact with limestone: m c02g "'" mH2c03 +JT1HC0 3 + "tco ; (1) This quantity is plotted. in Figure I as a function of the partial pressure of the carbon dioxide, in the gaseous reservoir. The equilibrium constants quoted in Howard (I 966) were used in aJl calculations. When the groundwater is closed to .the atmosphere and brought ill" contact with limestone, additional carbon dioxide species are added to the groundwater due to solution of calcite, The quantity of these species attributable to solution of calcite, 111C0 2 S, equals the molality 'of the calcium ion: m cozs "'.m Ca ++ t Artlc!e bv Russell S. Harmon.appeared in Caves and Karst, Volume ,13, Numbers 3 (P'. 17-28} and 4 (p, 29-35), "Department of Env'iron~ental Sciences, University of Virginia, Charlottesville, VA 22903 **Department of Radiology (Nuclear Medicine}'-University of Virginia Hospital, Charlottesville, VA 22901 {2) 9

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CA VES AND KARST The equilibrium value of this quantity is plotted in Figure 1. Therefore, in closed-system equilibrium, the percentage of carbon dioxide species attributable to solution of lime" stone will be given by (Figure 1): 100 ffi C02S %C02S~~--~~~-ffi c02g + ffi C 0 2S Little dissolved carbon dioxide is added to solution during equilibrium with very low partial pressures of gaseous carbon dioxide, so that subsequent equilibration with limestone results in concentrations of calcium ion nearly equal to equilibration in pure water, giving a value of %C0 2 s near 100. However, this quantity is within the range of 40-60 for nearly 2 decades of carbon dioxide partial pressure. This range encompasses the partial pressures in soil gases, but the atmospheric partial pressure of carbon dioxide (about 103 5 atmospheres, according to GARRELS & CHRIST (1965): 82) faJls in the range where %C0 2 s is over 70. Thus the percentage of carbon dioxide species contributed by dissolution of limestone will vary with the initial partial pressure of carbon dioxide in the gas phase. The value of 8 J3 C m resulting from closed-system equilibrium between a groundwater (OI3Cl) which had equilibrated with a gas phase carbon dioxide reservoir (6 13 C g ) and a limestone with ol3C s would be: &"C = &13C + %CO,s (&13C a"C ) (41 m 1100 s 1 (31 Thus the carbon isotope ratio in ground waters derived from closed-system equilibrium will depend not only upon the isotope ratios of the inflowing surface waters and of the limestone, but also upon the partial pressure of carbon dioxide in the gas reservoir for .. merly in contact with the recharge water. The situation is even more complex in the case where limestone dissolution or precipitation occurs in contact with a gas phase; for example, in surface streams flowing on limestone, in cave passages with a free-water surface, and at the limestone-soil contact. The open-system equilibrium relationships (Case 2 of GARRELS & CHRIST (1965): 81 83) imply definite values of the concentrations of the various dissolved species, but they imply nothing about the sources of these species; hence the &13C value in the solution is indeterminate. The reason for this is the continuous exchange of carbon dioxide between the groundwater and the gas phase. The carbon isotope ratio in the groundwater will depend upon several factors, including the relative sizes of the gas and liquid reservoirs, the rapidity of exchange of species between the water and the gas phase (a function of the area of the interface and the degree of turbulent mixing), the length of time during which the two phases are in contact, and finally, upon the carbon isotope ratios in the gas phase and the limestone. If the period of free interchange of carbon dioxide is long and if the atmospheric reservoir is large, the carbon isotope ratio in the groundwater will approach isotopic equilibrium with the gas phase irrespective of the carbon isotope ratio of the limestone. Interpretation of carbon isotope ratios is even more difficult if the possibility exists that the groundwater is undersaturated with respect to limestone. The effect of undersaturation is to reduce the percentage of limestone-derived carbonate components in the water, and thus to produce carbon isotope ratios close to that of the soil water or rainwater, depending upon the principal source. Pearson and Hanshaw (1970) correct for this effect by determining the degree of saturation (or supersaturation) of the groundwater. Kinetic fractionation effects (HENDY, 1971) may also be important in highly undersaturated water. Isotopic equilibria Harmon (1971a: 25-26) discusses expected carbon isotope ratios in karstic groundwater under various conditions of equilibrium. His Equations 24 and 25, corrected above, can be made more general by taking into account fractionation effects of all dissolved carbon dioxide species. If the carbon isotope ratio for a groundwater solution (8 13 C I) is controlled by equilibration with a gaseous carbon dioxide reservoir (o13C g ), then, to 10

PAGE 5

VOLUME 14, NO 2 c o -, -, -, -, -, -, co ',
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CA VES AND KARST one-tenth penni! accuracy using the K* values for 20Â¡C quoted in Harmon (197 I a; Table 12): ifil where Xl X 2 and X3 are the relative proportions of the total dissolved carbon dioxide species composed of H 2 C0 3 HC03 and C0 3 -, respectively. Slightly different enrichmentfactora are quoted by Hendy (1971, Table 2) based on other fractionation data. Similarly, if the equilibrium isotopic ratios are controlled by equilibration with calcite, then; (6) In closed-system equilibrium the value of 0 13C I to be entered into Equation 4 will depend upon the partial pressure of the carbon dioxide prevailing during the equ.ilibration with the gas phase. The value of the permil correction (right-hand term in Equation 5) is plotted in Figure 2 as a function of the carbon dioxide partial pressure. During the subsequent closed-system dissolution of limestone, the isotopic composition of the carbonate species added to the groundwater from the limestone will equal the bulk isotopic composition of the calcite (5 13 C s ) as indicated in Equation 4, because fractionation cannot occur when the calcite is completely dissolved. Continuing dissolution of limestone in karst groundwater circulation must add. 13C and 12 C in proportion to their occurrence in the limestone, In, the open-system dissolution the isotopic ratios will be difficult to predict due to the many factors influencing the sources of the carbon dioxide species, as discussed above. In the limit where the carbon dioxide species have free exchange with a large atmospheric reservoir, the carbon dioxide species derive solely from the gas phase, and Equation 5 will be appropriate. Figure 2 shows the permil correction for 8 13 C g for various partial pres. sures of carbon dioxide in open system equilibrium. Equation 6 will seldom be appropriate for determining the carbon isotope ratio in groundwater which is either undersaturated or at equilibrium with limestone with a bulk isotopic ratio of 8 13 C s As pointed out above, actively dissolving limestone adds J3C and 12C without fractionation. At equilibrium Equation 6 will hold between the solution and a monomolecular layer on the limestone, and the value of 8 13 C[ will control the 8 13 C s value of this thin layer. Only if recrystallization Occurs within the limestone will fractionization with respect to the bulk isotopic ratio of the limestone control the carbon isotope ratio of the groundwater. Such reactions are very slow and are not likely to be important in near-surface hydrology. However, Equation 6 will be appropriate under conditions where the groundwater becomes supersaturated by loss of carbon dioxide or evaporation of water and deposits calcite as flowstone, tufa, etc. These deposits should be in isotopic equilibrium with the groundwater responsible if carbon dioxide loss is slow (HENDY, 1971), and, as Hannon (1971a: 26-27) and Hendy (1971) suggest, such deposits may afford a clue to past variations of carbon isotope ratios in the circulating groundwater. The value of the permil correction for limestone deposited in equilibrium with respect to groundwater is plotted in Figure 2 as a function of the partial pressure of carbon dioxide for the groundwater. Discussion Hannon (1971b) has measured carbon isotope ratios of samples of groundwater, spring water, and surface water in a drainage basin underlain largely by carbonate rocks, and he uses these measurements to make conclusions about the rapidity of groundwater flow underground and the type of recharge into the karst aquifer (direct or diffuse in. flow). However, inview of all of the factors discussed above, a given carbon isotope ratio measured in groundwater or surface water in a.karst area may not afford a unique indication of the chemical and hydrologic history of the water; the same carbon isotope ratio may possibly arise from various combinations of source of gaseous carbon dioxide (e.g., .the atmosphere with 8 13 C near -7'1 00 (HARMON, 1971a: 18) or soil air with 8 13 C of about -,22 "too (HARMON, 1971 a: 18), saturation versus undersaturation, and type of equilibrium (open-system, closed-system, or some more complicated history). In addition, the quantity, isotopic ratios, and sources of dissolved carbon dioxide species are affected 12

PAGE 7

VOLUME 14, NO 2 by temperature differences within the groundwater flow system as well as by biologic activity within the water. The potential usefulness of carbon isotope ratios as indicators of the sources and chemical evolution of karstic groundand surface-waters can best be determined with. in the context of an extensive monitoring of a karstwater system, where the role of the many factors influencing the chemical evolution of a natural water system can be empiricaJJy determined. In addition to monitoring carbon isotope ratiosin rainfall, soil water, groundwater, and surface water over a period of a year or more, supplemental information should be obtained DlJ. water temperature, chemical composit.ion of the water, flow patterns, flow rates, flow volumes, nature of underground openings, and chemical and isotopic composition of the rocks involved. Under such a sampling plan it should be possible to assess to what degree the measurement of carbon isotope ratios can substitute for the difficult and expensive determination of the underground flow regime and the sources and chemical evolution of the groundwater. Although Hannon (1971 b) has measured carbon isotope ratios on amoderate number of samples from springs, wells, and surface streams, little supplemental information is provided of the types mentioned above. Because of the many factors influencing the carbon isotope ratio in water, a more intensive study will be necessary before its measurement can be recommended in routine karstwater analysis. However, Harmon has performed a'valuable service in calling to the attention-of researchers in karst hydrology a potentially valuable tool. References GARRELS, R.M. & C.L. CHRIST (1965). Solutions, Minerals, and Equilibria. Harper & Row, New York, 450p. HARMON, R.S. 0971a). The application of stable carbon isotope studies to karst research: Part l, Background and theory. Caves and, Karst 13: 1728. HARMON, R.S. 0971b). The application of stable carbon isotope studies to karst research: Part II, An example from central Pennsylvania. Caves and Karst 13; 2935. HJ?;NDY, C.H. (971). The isotopic geochemistry of speleothems-L The calculation of the effects of different modes of formation on the isotopic composition of speleothems and their applicability as palaeoclimatic indicators. Geochimica et Cosmochimica Acta 35; 80[-824. HOWARD, A.D. (966). Verification of the Mischungskorrosion effect. Cave Notes 8: 9-12. PEARSON, F.J. & B.B. HANSHAW (1970). Sources of dissolved carbonate species in groundwater and their effects on carbon-La dating. (in Isotope Hydrology 1970). International Atomic Energy Commission, Vienna: 271-286. G"'-'~G'-..-'~~ THE APPLICATION OF STABLE CARBON ISOTOPE STUDlES TO KARST RE.SEARCH: REPLY By RUSSELL S. HARMON* From the discussion by Howard & Howard (1972) of rriy two papers treating the potential of stable isotope studies to karst research, it appears that additional clarification is necessary. They have called attention to one major error of omission' in the stating of the fractionation equilibrium equations; but their discussion and calculation of isotopic effects for different solution models is strictly an academic exercise, having been done three years earlier in much greater depth and detail by. Hendy(l,969). Corrections . Howard & Howard (I97'2) have indicated that "several equations in the first paper by Harmon (l971a) appear incorrect." They have correctly pointed out the omission of a multiplication factor of 10 6 necessary for the correct expression of the fractionation equilibrium expressions in Equations 1214. The equations should read: 1000 In K o = 0.912 + 0.0063 (lIT') xl0' OK 1000 In K, = 4.537 + 1.0985 (lIT') xl0' OK 1000 In K 3 = 3.628 + 1.1941 (lIT') xl0' OK "Department of Geology. McMaster University, Hamilton, Ontario. 13

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I I I I CA VES AND KARST The correction recommended for Equation 25 is unnecessary, and the expression is COT rect as stated. Carbonate solution models There exist sets of conditions by which carbonate rock can be dissolved by a 501u tion of carbon dioxide and water. The "open system" case arises where limestone solution occurs in the presence of an excess of C02 (Case 2 of GARRELS & CHRIST (1965)). The "closed system" case occurs when limestone is dissolved in a water initially equilibrated with, but subsequently removed from, a C02 reservoir (Case 5 of GARRELS & CHRIST (1965)). These two situations represent end-member cases and most natural systems are most likely varying degrees of combination of these two extreme cases. In the closed system, a quantity of water is allowed to equilibrate with a reservoir of defined C02 pressure; in most cases the soil zone, but equilibration with the atmosphere is also possible. The water is then isolated from the reservoir so that exchange of CO 2 between the solution and the reservoir is impossible. In most natural cases this represents the movement of downward percolating water from the soil into the carbonate rock along small joints and cracks. Only in the case where large fractures or fissures exist is the possibility of C02 exchange (replenishment) at great depths realistic. This is especially true in areas where soil profiles are thick and extend below the level of active plant inhabitance, since C02 in the soil is primarily a result of biogenic processes, such as plant respiration and the decay of organic material. Once out of contact with the C02 reservoir, the water begins to dissolve carbonate rock until equilibrium is reached or the process is interrupted by the water entering a cave or returning to the surface at a spring. The chemistry of carbonate solution under closed system conditions has been thoroughly' described by Garrels & Christ (1965), Thrailkill (1968), and Langmuir (1971); and duplicated by Howard & Howard (1972). The nature of the solution reaction in the closed system is such that the total amount of dissolved carbon in solution as H2COg, HC03-, and C032is dependent on two factors; the initial CO 2 pressure of the reservoir with which the solution was equilibrated, and the temperature at which the solution of the carbonate occurs. The isotopic composition of the total solution, :2;8 13 C, is, in addition, also a function of the isotopic compositions of the CO 2 reservoir and the limestone. The concentrations of dissolved carbon species can thus be calculated for any set of P CO~ and temperature conditions. Using the calculated concentrations, the 13 C/ 12 C ratio for the total solution can be determined. These calculations have been made for C02 pressures from 104 to 101 atm. and temperatures from 0-25Â¡C by Hendy (1969) using an iterative method. The resultant 8 13 C values are listed in Table 1 for various C02 pressures at 12Â¡C. It will be recalled from my first paper (HARMON, 1971 a) that an example of such a calculation was made for closed system conditions at a pH of 7.5 and a temperature of 10Â¡C. The resultant 8 J 3C value compares favorably with that obtained by Hendy at 12 Q C. In their calculation, Howard & Howard (1972) account only for the temperature effect at 20Â¡C and thus their "general" expressions for the calculations of 8 13 C for solution under closed system conditions are meaningless for most real situations where water temperatures may range from 1O-25Â¡C. Isotopic compositions in the "open system" case were declared by Howard & Howard (1972) to be "difficult to predict due to the many factors influencing source of carbon dioxide species." This statement indicates a definite lack of understanding of the problem as a whole. Under open system conditions, carbonate solution occurs in the presence of an excess of CO 2 provided from an infinite reservoir, thus making the problem much simpler, not more complex as Howard & Howard (1972) have stated. Thus because the amount of ~02 in the reser~ojr is. assumed to be in excess and exchangeab/~, the isotopic composihan of th~ sol~tton, Will closely approach that of the reservoir, taking into account necess~ry fractt~~atl?~ effe.cts, ~d will be u~affected by the isotopic composition of the limestone. CI C ratios are still a function of CO 2 pressure of the reservoir and temperature of the water, and can be calculated directly from the expression ,"c r13C "C u x u (C0 2 gas) + Ex 14

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VOLUME 14, NO.2 -1. C E B D: I , , ,Z ,0 ,,,< ,~ ,0> ,~ ,< ,~ I D: , , I I w ,~ 1,U ,1< ,u I A -5 -10 -22 ,., .. 10 9 P CO ("m~ ... ~ ~~ i \E 3 I I I C pH B __ ------------~---<~D~I A : I I I 6 200 HC0 3 0 Ca 2 + ppm '00 B ~R~ ~ :"' -5 -4 -3 -2 -1 0 +1 Sic A A 1<;:__ Figure 1. Comparison of the progres~ive charlgc, in various parameters with residence time {measured in terms ot SIc) in the karst drainage oasto. The data points represent the mean value lor each of the water tvpes sampled where 8 13 C x is the isotopic composition of an individual carbon species in solution and Ex is the appropriate fractionation factor as calculated in HARMON (t971a). The total isotopic composition of the solution can be determined from Equation 23 of HARMON (1971a). Hendy has calculated 5 13 C values for carbonate solutions under open system conditions for various C02 pressures and temperatures. These values are listed in Table 1 for 12Â¡C. Again it is seen that the example calculated in my 1971a paper for a pH of 7.5 and a temperature of 10Â¡C agree well with Hendy's value at 12Â¡C. 15

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CA VES AND KARST P eo in the soil atmosyhere i % atrn] 5.16 s.os 3.21 1.H 2.0.1 I ,2~ O'H o.er 0.34 0.11 li 13 C (open system) "'00 _173 -17.2 -16.H -16.6 -II,J 16.1 -te.o 15,'! -[5,(, 15.3 1l 13 C (closed system) 'to<> -13,1 -13.0 -12.4 _12.1 -12.0 --11.7 [1.6 \1.5 11.5 -1104 Table 1. Equihbrlum /iIlC T as a fuoctio n 01 P ClJ for the solution 01 limestone (1iIJC~-l;l~,,,1 in the presence and absence of a !las phase at 10Â¡C [fr-om HENDY, 1969l. Applied study The discussion of my 1971 b paper by Howard & Howard questioned the, validity of interpretation of the data due to what they imply are complications in the solution models. It has just been shown that models are well understood and that isotopic ccmpositions can be predicted for both the open system and closed system cases. It should also be pointed out that under no conditions do the predicted values for the two cases overlap. Open system values are always less than closed system values by about 4~oo' The fact that Howard & Howard were not aware that their difficulty in predicting isotopic composttions in the open system had been solved by Hendy (1969), and that the necessary chemical data for the waters sampled was available (HARMON E1 AL., in preparation) reduces the necessity for questioning the results; however, certain additional clarifications are felt to be necessary at this time. That the degree of saturation of a water is a direct measure of its age within a karst drainage basin has been clearly illustrated by Jacobson & Langmuir (1970). Additionally, Harmon and others (in press) have pointed out-that the water-type classifications used in my paper (Harmon, 1971 b) represent statistically different sample populations. Figure 1 shows the changes in chemical and isotopic character of the water types as a function of age within the basin (Sid. That the 5 13 C values increase linearly with age, is evident; thus indicating that 8 13 C, as previously stated in my 1971 b paper, is alsoa good measure of the age of a water within the basin. The other important point stressed in that paper was that ground waters within the drainage basin had equilibrated primarily under closed system conditions. The mean 8 13 C value of the 21 diffuse spring and well waters sampled was ~ 2.51
PAGE 11

\ , Distri6'I/idn:' @\:v,ES AND KARST reaches-an audience er!. Stien,iBe n~me1 sho~ld be Clarified by thei'r cOP,Ilo,n.harqes ,~l~en,first(cfted; if 'none\, then ~ v~rnatul~ eq~ivjllent;o,f the! get~:us Q1' fa.nll1f 1& teeo.qJ.fOenUed.. All mea,$UIements should be l,Ptnett1C OO1ts, .Â£bllowb:! by English equiv~J~~ts If desice~"or nec~ary 'Â£o~ ,indi9lJ.tmg' accuraCYI 11:11 \'equa,tjons and tabl., m~ste h[1OJ;Oughly ~hecked. fJ9th in,\he,man\lscript an\! g.lley.!i/'\iuscripr shoufd be ne,tly typed ilt doub!eOJ; triple.spaced Bnes. FOlmats' of cent ISSue' o/, cA. VES .t\NP KARST may be used ... mO,de!s. I' FqdtniJles a.d,r'f.,em;~s: The .. ,s~o:Ud Use ,as tH,ir mMel i~ent )ssue~ 'of, CAvEs AND KAltSJ. Authors shqi11d ~ive th~it institutiOn, al affiliatiQD aDd address ~ctly ~s 'it is t,p)ap~,ear In Â£,rirltc..References sbay,1fl cOJ)wn,~ ~nfpnv.atiotl, Qe~es'sanr igl 1oeaci98 the item 1 with tides \it! j()urbals t~,mpletelr spe,U:ed' out if!, tbeit'oc\gitM 1ao!Nage, in clu8ing all ~i.cri'ioal tparlts, Pag~ nwpbtrs of artides anI! total 'pUinBer of pages 01 books must be incl,Ja,lj. 'I' I PhQtQgrapbr: Drewiqgt' conr.inlQg' ton,~ 61 grey, and photogtaphS r,qnii\i half.tone (eploducrion.' Phntoo:,jhould b, supmit~~d ~s' gl05.lY plllck,and lv!\j,e .frin" of consider able contlr.lst. Largeslzea ph0tQS arefr~feqed :lad should coq-bUb an m~lCat10n of scaJe~ unl~ss dini,ensions, are indicated in fhe,caption. l j' I ',; l I Litle drawings aiM fliag-~MfJ" 'the~ 'sb(,\l!d Be draw\) iq iridi~: 1nk. All except schemadc type dC'olwings should cO.Q.talrt a mer~i.c soalÂ¢, OC, dimensions shOulli b,e provide~ lO the caption. :N:agnilioatiQQ figures arelnot,sa(isf~atory. Maps~ in addition, s~ould cooram 1 arrow ihdicating\t~ nOrtA. ot othe.\1 di!.~tiof\' indif;;ator.~tteri~8 sgould be. doo!= with, C$!e-u~ing ~ithe,. considc!labl 1 e ~[t~strr. dr mecharo~al ajds. iPres$-on lett:rs giv~~,cellent tesul" w.l>en ~ropetly slig~~d. Pt",sntl shading and symbols vadable at art stores, ar~!llso rec9ffimendca. 'fhe,s~ &PQ lettedng should be (;hOsen wit 'th~, eqtet~ si~. '/lQ" ,~do 800~3, I PAGE 12 CAVE RJ;:SEAJ~Cll ASSOCIATES Price List o~' Publications CA VEil AND KARST '(formerly CAVJ; NOTES): A journal of research in the karst and cave sciencesJ{'ublished bimonthly and containing ~i;Chnical papers, reviews, notes, and annotated bibliographies of current literature, l.. Current Volurnes: ", I "'olume 14 (\972) : : -r$3.25 Volumes)4 through 16 :.... 7.50 , Earlier Volumes Volumes 1,2,3 (each) :., : .. $1.{)0 Volumes 4 through 8 (each) .. : .. : ,; :.,., 2.00 Volumes 9 through 12 (each) , .. ; ::. 2.50 Volume 13 on (each) C'.: , 3.25 Volumes I through 13 (1959 (971) complete, \ncludin~ 3year indexea" '; ................ ".1 .. '. : 26.25 Single issues and indexes ~ .. ,,' ","" ,_ ':: ", _, 1 Pri~~ on request. , CAVE StUDIES: Monographs in the cave sciences ." I" Numbers 1 11: A bound volume of II papers published between 1953 aod 1959. Price$3.00 (outQfprint)., Number 12: All Bthno-Archaeatogtcal Examinatioi: of Samwd/ea.~, b>< Adao ~. Tregenza, With figures, photographs and maps. Price $2.00. .'. I I A ., '" AlL pnces inc1u~. postage: Quantity rates to authors a'~d others-are available on'request. P1e:l$O make checks and money.orders paya~le to CAYE RESEARCH ASSOCIATES, 3842 Brookdale Blvd., Castro Valley, CaJiIotnia, U.S.A. 94546-. British subscriber, may pial'" their orders direcUy'wjthCA VERESEARCH ASSOClA'FES, c/o Mr. Tony Oldham, 17 Freernantle Rd., Eastville, Bristol, England BS5 6S)'. "To insure prompt handling of subscrlptism correspondence; pl~a~e cut out and~ricll;)se previous sddr;s~ label (corrected if necessary) aIQIll:, I"ith.xlf.ad

Description
Contents: The application of stable isotope studies to
karst research: discussion / Alan D. Howard & Barbara Y.
Howard --
The application of stable isotope studies to karst
research: reply / Russell S. Harmon.
Cave Notes(vols. 1-8) and
Caves and Karst: Research in Speleology(vols. 9-15)
1975, the Tumbling Creek Cave Foundation compiled complete
sets of the journals in three volumes. The Foundation sells
hardbound copies of the material to support its
activities.