Migration and Distribution Fluxes of Plutonium Radioisotopes in Coastal Semiclosed Marine Areas

Abstract—The article presents the results of a quantitative determination of the migration and distribution fluxes of plutonium radioisotopes ^{239 + 240}Pu in coastal semiclosed marine ecosystems from a case study example of Sevastopol Bay (Black Sea) to assess the self-purification of water masses from ^{239 + 240}Pu. The assessment was based on a study of the current (2018–2021) levels of the activity concentration of ^{239 + 240}Pu in water, bottom sediments, perennial brown macroalgae, and benthic fish. It has been found that the main ^{239 + 240}Pu removal flux (more than 93% of the total flux), which determines the self-purification of water masses with respect to ^{239 + 240}Pu in coastal marine areas is the sediment flux of suspended particle matter, which causes redistribution of ^{239 + 240}Pu into bottom sediments. ^{239 + 240}Pu migration to neighboring water areas due to hydrological processes is insignificant, as well as the decrease in ^{239 + 240}Pu in the ecosystem due to radioactive decay. In total, these processes accounted for less than 1% of the total flux. The interaction of ^{239 + 240}Pu with macrobiota accounted for almost 6%, of which more than 5% was provided by macrophytes.