Determination of distribution coefficient of uranium from physical and chemical properties of soil

Uranium is a long lived radioactive element which is naturally present in minute concentrations in igneous, sedimentary and metamorphic rocks. These rocks when subjected to weathering results in the formation of soil which also has traces of uranium. Distribution coefficient (K_d) is a crucial parameter in environmental assessment which is used to predict the interaction and transport of uranium in groundwater. The objective of the study is to estimate the K_d of uranium in soils and to develop a relation between this and the soil parameters. Seven rock samples and twenty three soil samples were collected during this study. The K_d of rock samples of different grain sizes where determined and the soil samples were analysed for electrical conductivity, pH, grain size, bulk density, particle density, porosity, calcium carbonate, cation exchange capacity and K_d. The K_d of the soil increases with increase in soil pH up to 6, after which it gradually decreases. Multiple regression analysis was performed to quantify the effect of various soil parameters on soil K_d and equations were statistically significant. Thus, soil K_d in a region could be predicted using limited soil properties with such statistically significant equations.