Distribution and migration of 239+240Pu in abiotic components of the Black Sea ecosystems during the post-Chernobyl period

Abstract

Distribution of 239,240Pu in abiotic components (water and bottom sediment) of the Black Sea ecosystems was studied during the post-Chernobyl period at different offshore and near-shore locations. The trends of these radionuclides accumulation by sediments were analyzed. The spatial-temporal changes in the 239,240Pu distribution as well as effective half-life for these radionuclides in the Black Sea surface water in deep-sea area are presented. The estimations of the average annual removal fluxes of the 239,240Pu into the bottom sediments were obtained. The Black Sea sediments were characterized by a higher 239,240Pu concentration factor (Cf ≈ n·104–n·106) and radiocapacity factor (F(239,240Pu) was about 99.9% on the shelf, 94.5–99.1% on deep-sea basin for silty and 94.6–98.9% on the shelf for sandy bottom sediments) as compared with Cf and F for 137Cs and 90Sr. Silty bottom sediments play the role of 239,240Pu main depot in the Black Sea ecosystem. The studied radioecological characteristics of Pu allowed us to define the type of plutonium biogeochemical behavior in the Black Sea as a pedotropic one. The results of this complex radioecological monitoring of 239+240Pu contamination in the Black Sea and their analysis makes it possible to understand the plutonium redistribution pathways which will enable to carry out the tracing of its migration within the ecosystems.