The influence of a capacitor plant in Serpukhov on vegetable contamination by polychlorinated biphenyls.

PCB content in soil and vegetables grown on the polluted soils in some districts of the town of Serpukhov have been studied for 10 years after the use of PCBs had been banned at the local capacitor plant. Soil contamination with PCBs in the vicinity of the plant is still extremely high (up to 30 mg/kg). Vegetables grown on the polluted soils, especially carrots and green parts of fennel, parsley, celery are also highly contaminated. The primary pollutants are found to be tri- and tetrachlorobiphenyls (up to 70-80% of total PCBs).

Behaviour of long-lived Chernobyl radionuclides in a soil-water system.

Field and laboratory experiments have been used to study the behaviour of long-lived radionuclides in the zone affected by the Chernobyl accident. Speciation of 90Sr and 137Cs in soils and bottom sediments was determined. The principal distinction of the Chernobyl fallout was that it contained a relatively small proportion of exchangeable forms because a considerable fraction of the radionuclides was incorporated as part of the insoluble fuel particles. Disintegration of fuel particles in soils and bottom sediments results in transition of non-exchangeable forms into exchangeable forms. Radionuclide species have different pathways and rates of migration in soils and bottom sediments. Migration of each chemical form was described by a convective-dispersive equation taking into account transformation processes of radionuclide species in soils or bottom sediments. Adsorption of 90Sr and 137Cs in the environment is controlled by the cation-exchange capacity and the selectivity of the solid phase (i.e., soil, bottom sediments and suspended matter) and the cationic composition of the liquid phase (i.e., soil solution, surface run-off and river or lake water). The corresponding parameters for the processes were obtained.