UNDERSTANDING VARIATION IN PARTITION COEFFICIENT, Kd ...

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FOREWORD Understanding the long-term behavior of contaminants in the subsurface is becoming increasingly more important as the nation addresses groundwater contamination. Groundwater contamination is a national concern as about 50 percent of the United States population receives its drinking water from groundwater. It is the goal of the Environmental Protection Agency (EPA) to prevent adverse effects to human health and the environment and to protect the environmental integrity of the nation’s groundwater. Once groundwater is contaminated, it is important to understand how the contaminant moves in the subsurface environment. Proper understanding of the contaminant fate and transport is necessary in order to characterize the risks associated with the contamination and to develop, when necessary, emergency or remedial action plans. The parameter known as the partition (or distribution) coefficient (K d) is one of the most important parameters used in estimating the migration potential of contaminants present in aqueous solutions in contact with surface, subsurface and suspended solids. This two-volume report describes: (1) the conceptualization, measurement, and use of the partition coefficient parameter; and (2) the geochemical aqueous solution and sorbent properties that are most important in controlling adsorption/retardation behavior of selected contaminants. Volume I of this document focuses on providing EPA and other environmental remediation professionals with a reasoned and documented discussion of the major issues related to the selection and measurement of the partition coefficient for a select group of contaminants. The selected contaminants investigated in this two-volume document include: chromium, cadmium, cesium, lead, plutonium, radon, strontium, thorium, tritium ( 3 H), and uranium. This two-volume report also addresses a void that has existed on this subject in both this Agency and in the user community. It is important to note that soil scientists and geochemists knowledgeable of sorption processes in natural environments have long known that generic or default partition coefficient values found in the literature can result in significant errors when used to predict the absolute impacts of contaminant migration or site-remediation options. Accordingly, one of the major recommendations of this report is that for site-specific calculations, partition coefficient values measured at site-specific conditions are absolutely essential. For those cases when the partition coefficient parameter is not or cannot be measured, Volume II of this document: (1) provides a “thumb-nail sketch” of the key geochemical processes affecting the sorption of the selected contaminants; (2) provides references to related key experimental and review articles for further reading; (3) identifies the important aqueous- and solid-phase parameters controlling the sorption of these contaminants in the subsurface environment under oxidizing conditions; and (4) identifies, when possible, minimum and maximum conservative partition coefficient values for each contaminant as a function of the key geochemical processes affecting their sorption. iii
This publication is the result of a cooperative effort between the EPA Office of Radiation and Indoor Air, Office of Solid Waste and Emergency Response, and the Department of Energy Office of Environmental Restoration (EM-40). In addition, this publication is produced as part of ORIA’s long-term strategic plan to assist in the remediation of contaminated sites. It is published and made available to assist all environmental remediation professionals in the cleanup of groundwater sources all over the United States. iv Stephen D. Page, Director Office of Radiation and Indoor Air
Page 1 and 2: United States Office of Air and Rad
Page 3: NOTICE The following two-volume rep
Page 7 and 8: TO COMMENT ON THIS GUIDE OR PROVIDE
Page 9 and 10: CONTENTS NOTICE ...................
Page 11 and 12: Concentrations Extractable Iron Con
Page 13 and 14: Appendix A - Acronyms and Abbreviat
Page 15 and 16: Figure E.1. Variation of K d for Cr
Page 17 and 18: Table 5.16. Uranium(VI) aqueous spe
Page 19 and 20: Table H.3. Simple and multiple regr
Page 21 and 22: 1.0 Introduction The objective of t
Page 23 and 24: discussed. The geochemical modeling
Page 25 and 26: 2.0 The K d Model The simplest and
Page 27 and 28: track many more parameters and some
Page 29 and 30: of interest. The retardation factor
Page 31 and 32: (e.g., soil). An increasing body of
Page 33 and 34: complexation constants for the cont
Page 35 and 36: the soil column. Additionally, the
Page 37 and 38: Element Table 5.2. Concentrations o
Page 39 and 40: 5.2.3 Aqueous Speciation Cadmium fo
Page 41 and 42: 5.2.4 Dissolution/Precipitation/Cop
Page 43 and 44: cadmium, indicating that cadmium an
Page 45 and 46: 5.2.6.2.2 Limits of K d Values with
Page 47 and 48: 5.3.4 Dissolution/Precipitation/Cop
Page 49 and 50: organic chelates (e.g., EDTA). Init
Page 51 and 52: 5.3.6.2.1 Limits of K d Values with
Page 53 and 54: (tarapacaite) in chromium sludge fr
Page 55 and 56:
K d). Soils containing Mn oxides ox
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Table 5.7. Estimated range of Kd va
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most common valence state of lead e
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Table 5.8. Lead aqueous species inc
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Under reducing conditions, galena (
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C Adsorption of lead increases with
Page 67 and 68:
5.5.6.2.2 Limits of K d Values with
Page 69 and 70:
(Choppin, 1983). Plutonium hydrolyt
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Table 5.10. Plutonium aqueous speci
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5.6.5 Sorption/Desorption Plutonium
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content in the system. Additionally
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5.6.6.2.2 Limits of K d Values with
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5.7.4 Dissolution/Precipitation/Cop
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much greater concentrations. Thus,
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exchanged which they attributed to
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up tables was based in part on thei
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organic complexes likely predominat
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Thorium undergoes hydrolysis in aqu
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The distribution of thorium aqueous
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from about 10 -8.5 mol/l (0.0007 mg
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Based on the assumptions and limita
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5.10 Tritium Geochemistry And K d V
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uranium. Uranium(VI) species domina
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gives 0.1 to 10 µg/l as the range
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mineral in reducing ore zones (Fron
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Percent Distribution 100 80 60 40 2
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5.11.6 Partition Coefficient, K d ,
Page 109 and 110:
No attempt was made to statisticall
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Table 5.18. Selected chemical and t
Page 113 and 114:
Another objective of this report is
Page 115 and 116:
6.0 REFERENCES Adriano, D. C. 1992.
Page 117 and 118:
Bensen, D. W. 1960. Review of Soil
Page 119 and 120:
Metals by Geomedia. Variables, Mech
Page 121 and 122:
EPA (U.S. Environmental Protection
Page 123 and 124:
Griffin, R. A., A. K. Au, and R. R.
Page 125 and 126:
+ Keeney-Kennicutt, W. L., and J. W
Page 127 and 128:
Mattigod, S. V., A. L. Page, and I.
Page 129 and 130:
Oscarson, D. W., and H. B. Hume. 19
Page 131 and 132:
Relyea, J. F. and D. A. Brown. 1978
Page 133 and 134:
Schultz, R. K., R. Overstreet, and
Page 135 and 136:
Szalay, A. 1964. “Cation Exchange
Page 137 and 138:
Yariv, S., and H. Cross. 1979. Geoc
Page 139 and 140:
APPENDIX A Acronyms, Abbreviations,
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PC Personal computers operating und
Page 143 and 144:
A.3.0 List of Symbols and Notation
Page 145 and 146:
APPENDIX B Definitions
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Clay Content - particle size fracti
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Polynuclear Species - an aqueous sp
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C.1.0 Background Appendix C Partiti
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Cadmium K d Table C.2. Correlation
Page 155 and 156:
C.3.0 Data Set for Soils Table C.4
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Cd K d (ml/g) Clay Cont. (wt%) pH C
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D.1.0 Background Appendix D Partiti
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A second data set (see Section D.4)
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Table D.3. Correlation coefficients
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By transposing the CEC and cesium K
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Table D.6. Cesium K d values measur
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eported in Table D.8 are described
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a 1 b 1 Range of Solution Cs Concen
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Figure D.4. Generalized cesium Freu
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Table D.10. Estimated range of K d
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D.3.0 K d Data Set for Soils and Pu
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Cesium Kd (ml/g) Clay (wt.% ) Mica
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Page 191 and 192:
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Cesium K d (ml/g) Clay (wt%) Mica (
Page 195 and 196:
Bruggenwert, M. G. M., and A. Kamph
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Shiao, S. Y., P. Rafferty, R. E. Me
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E.1.0 Background Appendix E Partiti
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chromium-reductive soils may stem f
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E.2.0 Approach The approach used to
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Table E.3. Estimated range of K d v
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Table E.4. Data from Rai et al. (19
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E.4.0 References Davis, J. A. and J
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APPENDIX F Partition Coefficients F
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(CEC) of the soils. Such an anomaly
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Table F.1. Summary of K d values fo
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Figure F.2. Variation of K d as a f
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F.4.0 References Abd-Elfattah, A.,
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APPENDIX G Partition Coefficients F
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A number of investigators have exam
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pH value, which is typical of the m
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These significant reductions in ads
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This is typically accomplished by t
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The scatterplots are typically disp
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Table G.2. Regression models for pl
Page 236 and 237:
G.4.0 References Barney, G. S. 1984
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Nelson, D. M., R. P. Larson, and W.
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APPENDIX H Partition Coefficients F
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1.6 ml/g for a measurement made on
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Figure H.1. Relation between stront
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Figure H.2. Relation between stront
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H.2.4 Approach Figure H.4. Relation
Page 250 and 251:
A second look-up table (Table H.5)
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Sr K d (ml/g) Clay Content (%) pH C
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Sr K d (ml/g) Clay Content (%) pH C
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Sr K d (ml/g) Clay Conten t (%) pH
Page 258 and 259:
Page 260 and 261:
Page 262 and 263:
Page 264 and 265:
Konishi, M., K. Yamamoto, T. Yanagi
Page 266 and 267:
APPENDIX I Partition Coefficients F
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descriptive statistics of the thori
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Figure I.1. Linear regression betwe
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The look-up table (Table I.5) for t
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Thorium K d (ml/g) pH Clay (wt.%) C
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Rai, D., A. R. Felmy, D. A. Moore,
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J.1.0 Background Appendix J Partiti
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J.2.2 Uranium K d Studies on Soils
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Washington. The studies included an
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and then decreases with increasing
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Kd (ml/g) 100,000 10,000 1,000 100
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papers. Warnecke et al. (1984) indi
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Anderson et al. (1982) summarize an
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McKinley and Scholtis (1993) compar
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In a similar comparison of sorption
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J.3.1 K d Values as a Function ff p
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discussed, and one would have to ma
Page 300 and 301:
al., 1992; and others). These refer
Page 302 and 303:
· Manskaya et al. (1956) studied a
Page 304 and 305:
concentrations of humic acid, there
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pH U Kd (ml/g) Clay Cont. (wt.%) CE
Page 308 and 309:
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Page 312 and 313:
Page 314 and 315:
Page 316 and 317:
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Page 324 and 325:
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J.6.0 References Ames, L. L., J. E.
Page 328 and 329:
Erikson, R. L., C. J. Hostetler, R.
Page 330 and 331:
R. C. Ewing. Materials Research Soc
Page 332 and 333:
Sheppard, M. I., and D. H. Thibault
Page 334:
Yamamoto, T., E. Yunoki, M. Yamakaw
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