Milan Đorđević

Using 137Cs measurements to estimate soil erosion rates in the Pčinja and South Morava River Basins, southeastern Serbia

The need for reliable assessments of soil erosion rates in Serbia has directed attention to the potential for using (137)Cs measurements to derive estimates of soil redistribution rates. Since, to date, this approach has not been applied in southeastern Serbia, a reconnaissance study was undertaken to confirm its viability. The need to take account of the occurrence of substantial Chernobyl fallout was seen as a potential problem. Samples for (137)Cs measurement were collected from a zone of uncultivated soils in the watersheds of Pčinja and South Morava Rivers, an area with known high soil erosion rates. Two theoretical conversion models, the profile distribution (PD) model and diffusion and migration (D&M) model were used to derive estimates of soil erosion and deposition rates from the (137)Cs measurements. The estimates of soil redistribution rates derived by using the PD and D&M models were found to differ substantially and this difference was ascribed to the assumptions of the simpler PD model that cause it to overestimate rates of soil loss. The results provided by the D&M model were judged to more reliable.

The Influence of Edaphic Factors on Spatial and Vertical Distribution of Radionuclides in Soil

This chapter summarises the edaphic factors affecting radionuclide spatial and vertical distribution in different soil types, with special emphasis on typical soil types in Serbia. The correlations between radionuclide and stable element content in soil and soil characteristics (particle size fractions, pH, carbonate content, organic matter content, cation exchange capacity, saturated hydraulic conductivity, specific electrical conductivity) are presented. These results provide insight into the main factors that affect radionuclide migration in the soil, which contributes to knowledge about radionuclide behaviour in the environment and factors governing their mobility within terrestrial ecosystems.