Understanding Variation in Partition Coefficient, Kd, Values Volume II

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Percent Distribution 100 90 80 70 60 50 40 30 20 10 0 CdCl + CdHCO 3 + 3 4 5 6 7 8 9 10 5.9 Cd 2+ pH CdCO 3 o (aq) o CdSO4 (aq) Figure 5.1. Calculated distribution of cadmium aqueous species as a function of pH for the water composition in Table 5.1. [The species distribution is based on a concentration of 1 micro g/l total dissolved cadmium and thermodynamic data supplied with the MINTEQA2 geochemical code.] Information available in the literature regarding interactions between dissolved cadmium and naturally occurring organic ligands (humic and fulvic acids) is ambiguous. Weber and Posselt (1974) reported that cadmium can form stable complexes with naturally occurring organics, whereas Hem (1972) stated that the amount of cadmium occurring in organic complexes is generally small and that these complexes are relatively weak. Pittwell (1974) reported that cadmium is complexed by organic carbon under all pH conditions encountered in normal natural waters. Levi-Minzi et al. (1976) found cadmium adsorption in soils to be correlated with soil organic matter content. In a critical review of the literature, Giesy (1980) concluded that the complexation constants of cadmium to naturally occurring organic matter are weak because of competition for binding sites by calcium, which is generally present in much higher concentrations.
5.2.4 Dissolution/Precipitation/Coprecipitation Lindsay (1979) calculated the relative stability of cadmium compounds. His calculations show that at pH values less than 7.5, most cadmium minerals are more soluble than cadmium concentrations found in oxic soils (10 -7 M), indicating that cadmium at these concentrations is not likely to precipitate. At pH levels greater than 7.5, the solubilities of Cd 3(PO 4) 2 or CdCO 3 may control the concentrations of cadmium in soils. Cavallaro and McBride (1978) and McBride (1980) demonstrated that otavite, CdCO 3, precipitates in calcareous soils (pH > 7.8), whereas in neutral or acidic soils, adsorption is the predominate process for removal of cadmium from solution. Jenne et al. (1980), working with the waters associated with abandoned lead and zinc mines and tailings piles, also indicate that the upper limits on dissolved levels of cadmium in most waters were controlled by CdCO 3. Santillan-Medrano and Jurinak (1975) observed that the activity of dissolved cadmium in cadmium-amended soils was lowest in calcareous soils. Baes and Mesmer (1976) suggested that cadmium may coprecipitate with calcium to form carbonate solid solutions, (Ca,Cd)CO 3. This may be an important mechanism in controlling cadmium concentrations in calcareous soils. Although cadmium itself is not sensitive to oxidation/reduction conditions, its concentration in the dissolved phase is generally very sensitive to redox state. There are numerous studies (reviewed by Khalid, 1980) showing that the concentrations of dissolved cadmium greatly increase when reduced systems are oxidized, such as when dredged river sediments are land filled or rice paddies are drained. The following 2 mechanisms appear to be responsible for this increase in dissolved cadmium concentrations: (1) very insoluble CDs (greenockite) dissolves as sulfide [S(II)] that is oxidized to sulfate [S(VI)], and (2) organic materials binding cadmium are decomposed through oxidization, releasing cadmium into the environment (Gambrell et al., 1977; Giesy, 1980). This latter mechanism appears to be important only in environments in which moderate to high organic matter concentrations are present (Gambrell et al., 1977). Serne (1977) studied the effect of oxidized and reduced sediment conditions on the release of cadmium from dredged sediments collected from the San Francisco Bay. Greater than 90 percent of the cadmium in the reduced sediment [sediment incubated in the presence of low O 2 levels (Eh350 mV). Cadmium concentrations released in the elutriate increased with agitation time. These data suggested that this kinetic effect was due to slow oxidation of sulfide or cadmium bound to organic matter bound in the reduced sediment prior to steady state equilibrium conditions being reached. In a similar type of experiment in which Mississippi sediments were slowly oxidized, Gambrell et al. (1977) reported that the insoluble organic- and sulfide-bound cadmium fractions in sediment decreased dramatically (decreased >90 percent) while the exchangeable and water-soluble cadmium fractions increased. Apparently, once the cadmium was released from the sulfide and organic matter fractions, the cadmium entered the aqueous phase and then re-adsorbed onto other sediment phases. 5.10
Page 1 and 2: United States Office of Air and Rad
Page 3 and 4: NOTICE The following two-volume rep
Page 5 and 6: This publication is the result of a
Page 7 and 8: TO COMMENT ON THIS GUIDE OR PROVIDE
Page 9 and 10: CONTENTS NOTICE ...................
Page 11 and 12: 5.6 Plutonium Geochemistry and K d
Page 13 and 14: Appendix C - Partition Coefficients
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.4. Look-up table for estima
Page 21 and 22: 1.0 Introduction The objective of t
Page 23 and 24: eviewed. The main focus of Volume I
Page 25 and 26: 2.0 The Kd Model The simplest and m
Page 27 and 28: no longer be used to perform the in
Page 29 and 30: of the velocity of the contaminant
Page 31 and 32: An increasing body of evidence indi
Page 33 and 34: contaminants of interest and the as
Page 35 and 36: dissolved gases and complexing liga
Page 37 and 38: Element Table 5.2. Concentrations o
Page 39 and 40: 5.6
Page 41: 5.8
Page 45 and 46: 1980). In contrast, zinc almost com
Page 47 and 48: 5.2.6.2.2 Limits of K d Values with
Page 49 and 50: 5.3 Cesium Geochemistry and K d Val
Page 51 and 52: Cesium may also adsorb to iron oxid
Page 53 and 54: Table 5.5. Estimated range of K d v
Page 55 and 56: ore processing, plating operations,
Page 57 and 58: elow the isoelectric point, the min
Page 59 and 60: Among all available data for Cr(VI)
Page 61 and 62: 5.5 Lead Geochemistry and K d Value
Page 63 and 64: on dissolution/precipitation of lea
Page 65 and 66: Percent Distribution 100 80 60 40 2
Page 67 and 68: A number of studies have confirmed
Page 69 and 70: Solid organic matter such as humic
Page 71 and 72: Plutonium is produced by fissioning
Page 73 and 74: The pe is related to Eh by the equa
Page 75 and 76: Table 5.10. Plutonium aqueous speci
Page 77 and 78: 5.6.5 Sorption/Desorption Plutonium
Page 79 and 80: conditions depended on the colloida
Page 81 and 82: 5.6.6.2.2 Limits of K d Values with
Page 83 and 84: present in vadose zone pore water w
Page 85 and 86: There is little tendency for stront
Page 87 and 88: strontium partitions from the disso
Page 89 and 90: greater than about 10 -4 M, humic s
Page 91 and 92: Table 5.13. Look-up table for estim
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1976; Cotton and Wilkinson, 1980).
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Table 5.14. Thorium aqueous species
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Figure 5.5 changes slightly in the
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to less than 10 -9 mol/l (0.0002 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(VI) species dominate in oxi
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most natural waters. For waters ass
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U(IV) mineral, is a primary mineral
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Percent Distribution 100 80 60 40 2
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5.11.6 Partition Coefficient, K d ,
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strong anionic carbonato complexes.
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Elemen t Table 5.18. Selected chemi
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Another objective of this report is
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6.0 REFERENCES Adriano, D. C. 1992.
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Billon, A. 1982. “Fixation D’el
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Chisholm-Brause, C., S. D. Conradso
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EPA/DOE/NRC (Cooperative Effort by
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Griffin, R. A., and N. F. Shimp. 19
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+ Keeney-Kennicutt, W. L., and J. W
Page 133 and 134:
McBride, M. B. 1980. “Chemisorpti
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Östhols, E. 1995. “Thorium Sorpt
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Rhoads, K., B. N. Bjornstad, R. E.
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Schwertmann, U., and R. M. Taylor.
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Tanner, A. B., 1980. “Radon Migra
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Zimdahl, R. L., and J. J. Hassett.
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APPENDIX A Acronyms, Abbreviations,
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PC Personal computers operating und
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A.3.0 List of Symbols and Notation
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APPENDIX B Definitions
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Cation Exchange - reversible adsorp
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subbituminous coal. Marl - an earth
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APPENDIX C Partition Coefficients F
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Mean Standard Error Table C.1. Desc
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Figure C.1. Relation between cadmiu
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Cd K d (ml/g) Clay Cont. (wt%) pH C
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APPENDIX D Partition Coefficients F
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Two separate data sets were compile
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The soil-only data set was frequent
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The high correlations between mica
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D.2.4 Cesium Adsorption onto Mica-L
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Table D.7. Approximate upper limits
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Table D.8. Freundlich equations ide
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Table D.9. Descriptive statistics o
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D.2.6 Approach to Selecting K d Val
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Mica Concentration in Clay Fraction
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Cesium Kd (ml/g) 15200 8440 143 73
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Cesium Kd (ml/g) Clay (wt.%) Mica (
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Cesium Kd (ml/g) Clay (wt.%) Mica (
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D.4.0 Data Set for Soils Table D.14
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Cesium K d (ml/g) Clay (wt%) Mica (
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Li, Y., L. Burkhardt, M. Buchholtz,
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APPENDIX E Partition Coefficients F
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Windsor, and Olivier soils with pH
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Table E.1. Summary of K d values fo
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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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influenced significantly by the typ
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The Pu(IV) and Pu(V) adsorption dat
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that Pu(IV) adsorption on soils wou
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Table G.1. Plutonium adsorption dat
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KD PH CEC EC DCARB Figure G.1. Scat
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Figure G.2. Variation of K d for pl
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Delegard, C. H. , G. S. Barney, and
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Seattle, Washington, pp. 291-497. B
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H.1.0 Background Appendix H Partiti
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H.2.0 Approach and Regression Model
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strontium K d values, which are cle
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Table H.3. Simple and multiple regr
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Table H.4. Look-up table for estima
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H.3.0 K d Data Set for Soils Table
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Sr K d (ml/g) Clay Content (%) pH C
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H.4.0 K d Data Set for Pure Mineral
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H.5.0 References Adeleye, S. A., P.
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Satmark, B., and Y. Albinsson. 1991
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I.1.0 BACKGROUND Appendix I Partiti
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Table I.2. Correlation coefficients
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The regression equation between the
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I.3.0 K d Data Set for Soils Figure
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I.5.0 References Ames, L. L., and D
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APPENDIX J Partition Coefficients F
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J.2.1 Sources of Error and Variabil
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Erikson et al. (1993) determined th
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26.1 wt.% plagioclase feldspar, and
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Kd (ml/g) 100,000 10,000 1,000 100
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Sheppard and Thibault (1988) invest
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Warnecke et al. (1986) present an o
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Borovec (1981) investigated the ads
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Table J.2. Uranium K d values liste
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J.3.0 Approach in Developing K d Lo
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at any pH. These estimated K d valu
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The minimum and maximum K d values
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ehavior associated with disposal of
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accompanied by unreacted zeolite. T
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pH Table J.5. Uranium K d values se
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pH U Kd (ml/g) Clay Cont. (wt.%) CE
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pH U Kd (ml/g) 6.90 1,739,87 7 6.90
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J.6.0 References Ames, L. L., J. E.
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Erikson, R. L., C. J. Hostetler, R.
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Lindenmeier, C. W., R. J. Serne, J.
Page 339 and 340:
Sheppard, M. I., and D. H. Thibault
Page 341:
Zachara, J. M., C. C. Ainsworth, J.
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Understanding Variation in Partition Coefficient, Kd, Values Volume II

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