Study of plutonium migration and/or accumulation in soil under field and laboratory conditions.

This study investigated the dependence of Pu3+ and Pu4+ vertical distribution on the soil characteristics in soddy and forest soil. Soil samples were analysed for organic matter and pH. Special columns with contaminated (239Pu) soil surface were kept for 326 days under field conditions. The analysis of the contaminated soil layers (5 cm each, totalling 20 cm) showed that 81% of 239Pu4+, 44% of 239Pu3+ and 82% of 239Pu4+, 61% of 239Pu3+ were accumulated in the 0-5 cm layer of soddy and forest soil. Sequential extraction of the soddy soil 30 days after surface contamination with 239Pu, 137Cs and 90Sr showed the following differences in radionuclide distribution: the largest amount of 239Pu (60%) and 137Cs (70%) were extracted from the residual fraction while 90Sr in this fraction reached only about 10%. This suggests that organic substances and some inorganic compounds, which usually are the main components of the residual fraction, affect the retention and migration of plutonium in the soil.