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Adsorption of radiocaesium on various soils: consequences of the effects of soil: solution composition on the distribution coefficient
Author(s) -
STAUNTON S.
Publication year - 1994
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/j.1365-2389.1994.tb00526.x
Subject(s) - freundlich equation , adsorption , soil water , chemistry , caesium , partition coefficient , potassium , clay minerals , cation exchange capacity , environmental chemistry , mineralogy , inorganic chemistry , soil science , chromatography , geology , organic chemistry
Summary The adsorption of a radioisotope of caesium, 137 Cs, has been interpretation and ratio and solution measured on four soils with differing clay mineralogies. All measurements have been made using unwashed soils in suspensions shaken for 2 h at 20°C. The effects of concentration in potassium and caesium, the nature of the background electrolyte and the soil:solution ratio have been investigated. The results are expressed either as the distribution coefficient, K D or as Freundlich isotherms. The distribution coefficient of each of the soils decreases markedly as the concentration of caesium increases. The adsorption properties of the soils are not determined by the dominant clay mineralogy alone. Adsorption is always lower in 0.01 m CaCl 2 solution than in water. The addition of potassium has relatively little effect on adsorption of trace amounts of caesium; however, K D decreases with increasing concentrations of stable caesium. The major reason for the dependence of K D on the soil: solution ratio is found to be the non‐linear adsorption isotherm; the influence of the varying compositions of the solution and exchange complex is minor. The validity of the use of a single K D value as an indicator of adsorption capacity and the meaning of the relative values of the Freundlich parameters are considered. The implications of these findings for the use of radiotracers and the usefulness of K D as an indicator of bioavailability are discussed.