UNDERSTANDING VARIATION IN PARTITION COEFFICIENT, Kd ...

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Table 5.13. Look-up table for estimated range of K d values for strontium based on CEC (meq/100 g), clay content (wt.%), and pH. [Tabulated values pertain to systems consisting of natural soils (as opposed to pure mineral phases), low ionic strength (< 0.1 M), low humic material concentrations (
organic complexes likely predominate over inorganic complexes in organic-rich waters and soils. This would have an important effect on the solubility and adsorption of thorium in such waters. Thorium-containing minerals, such as thorite, thorianite, monazite, and zircon, do not dissolve readily in low-temperature surface- and groundwaters. Because these minerals form at temperature and pressure conditions associated with igneous and metamorphic rocks, it is unlikely that the concentration of thorium in soil/water environments is controlled by the solubility of any of these minerals. The rate at which thorium is released to the environment may however be controlled by the rates of dissolution of 1 or more of these phases. The maximum possible concentration of thorium dissolved in low-temperature aqueous systems can however be predicted with the solubility of hydrous thorium oxide, because the solubility of this compound will result in higher concentrations of dissolved thorium than will likely occur from the kinetically-hindered dissolution of resistant primary thorium minerals. Moreover, hydrous thorium oxide solid is known to precipitate in laboratory experiments (i.e., short time periods) conducted at low temperature, oversaturated conditions. The concentrations of dissolved thorium in surface and groundwaters may also be controlled to low values by adsorption processes. Humic substances are considered particularly important in the adsorption of thorium. The available partition coefficient, K d, data indicates significant retention of thorium by most soil types. 5.9.2 General Geochemistry Twelve isotopes of thorium are known. Their atomic masses range from 223 to 234, and all are unstable (or radioactive) (Weast and Astle, 1980). Of these, 6 thorium isotopes exist in nature. These include: C C C 238 234 U decay series: Th [t½ (half life) = 24.1 d) and 230 Th (t½ = 8.0 x 10 4 y) 232 232 Th decay series: Th (t½ = 1.41 x 10 10 y) and 228 Th (t½ = 1.913 y) 235 231 U decay series: Th (t½ = 25.5 h) and 227 Th (t½ = 18.5 d). Natural thorium consists of essentially 1 isotope, 232 Th, with trace quantities of the other isotopes. Thorium is fertile nuclear material in that the principal isotope 232 Th can be converted by capture of a thermal neutron and 2 beta decays to fissionable 233 U which does not exist in nature. The application of thorium as a reactor fuel in the ThO 2 ceramic form is described in detail by Belle and Berman (1984). Thorium occurs only in the +4 oxidation state in nature. The Th 4+ ion is the largest tetravalent cation known with a radius of approximately 1.0 Å. Although the Th 4+ ion is more resistant to hydrolysis than other tetravalent ions, it forms a variety of hydroxyl species at pH values above 3 (Baes and Mesmer, 1976; Cotton and Wilkinson, 1980). The thorium content in natural water is very low. The concentration range in natural fresh water rarely exceeds 1 µg/l (0.1 pCi/l 232 Th), 5.54
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United States Office of Air and Rad
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NOTICE The following two-volume rep
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This publication is the result of a
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TO COMMENT ON THIS GUIDE OR PROVIDE
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CONTENTS NOTICE ...................
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Concentrations Extractable Iron Con
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Appendix A - Acronyms and Abbreviat
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Figure E.1. Variation of K d for Cr
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Table 5.16. Uranium(VI) aqueous spe
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Table H.3. Simple and multiple regr
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1.0 Introduction The objective of t
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discussed. The geochemical modeling
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2.0 The K d Model The simplest and
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track many more parameters and some
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of interest. The retardation factor
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(e.g., soil). An increasing body of
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complexation constants for the cont
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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 49 and 50: organic chelates (e.g., EDTA). Init
Page 53 and 54: (tarapacaite) in chromium sludge fr
Page 55 and 56: K d). Soils containing Mn oxides ox
Page 57 and 58: Table 5.7. Estimated range of Kd va
Page 59 and 60: most common valence state of lead e
Page 61 and 62: Table 5.8. Lead aqueous species inc
Page 63 and 64: Under reducing conditions, galena (
Page 65 and 66: C Adsorption of lead increases with
Page 69 and 70: (Choppin, 1983). Plutonium hydrolyt
Page 71 and 72: Table 5.10. Plutonium aqueous speci
Page 73 and 74: 5.6.5 Sorption/Desorption Plutonium
Page 75 and 76: content in the system. Additionally
Page 81 and 82: much greater concentrations. Thus,
Page 83 and 84: exchanged which they attributed to
Page 85: up tables was based in part on thei
Page 89 and 90: Thorium undergoes hydrolysis in aqu
Page 91 and 92: The distribution of thorium aqueous
Page 93 and 94: from about 10 -8.5 mol/l (0.0007 mg
Page 95 and 96: Based on the assumptions and limita
Page 97 and 98: 5.10 Tritium Geochemistry And K d V
Page 99 and 100: uranium. Uranium(VI) species domina
Page 101 and 102: gives 0.1 to 10 µg/l as the range
Page 103 and 104: mineral in reducing ore zones (Fron
Page 105 and 106: Percent Distribution 100 80 60 40 2
Page 107 and 108: 5.11.6 Partition Coefficient, K d ,
Page 109 and 110: No attempt was made to statisticall
Page 111 and 112: 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
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Yariv, S., and H. Cross. 1979. Geoc
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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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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
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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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Cesium K d (ml/g) Clay (wt%) Mica (
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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
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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
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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
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Konishi, M., K. Yamamoto, T. Yanagi
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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
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al., 1992; and others). These refer
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· Manskaya et al. (1956) studied a
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concentrations of humic acid, there
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pH U Kd (ml/g) Clay Cont. (wt.%) CE
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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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R. C. Ewing. Materials Research Soc
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Sheppard, M. I., and D. H. Thibault
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Yamamoto, T., E. Yunoki, M. Yamakaw
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