Distribution and migration of 90Sr in components of the Dnieper River basin and the Black Sea ecosystems after the Chernobyl NPP accident

The change in 90Sr concentrations in hydrobionts, water and bottom sediments of the Chernobyl NPP pond-cooler, the Kievskoe and Kakhovskoe reservoirs, the Northern-Crimean canal and the Black Sea after the Chernobyl NPP accident was studied. The environmental half-times for the decrease of 90Sr concentrations were determined: in water – 4.1–24.3 years; algae and flowering water plants – 3.6–7.7 years, in molluscs – 2.4–6.7 years, and in fish – 7.8–12.9 years. The time for 90Sr concentrations to decrease to pre-accident levels were estimated: in freshwater reservoirs and the northwest part of the Black Sea this was 32–44 years, and in freshwater hydrobionts this was 25–73 years. The contribution of dose from 90Sr to the hydrobionts, sampled from the Kakhovskoe reservoir, the Northern-Crimean canal and the Black Sea, has not reached values which could impact them during the entire post-accident period. This complex of comparative studies was carried out for the first time. -- Highlights: ► Regularities of change in 90Sr concentrations in the aquatic ecosystems were studied. ► Forecasts of time for 90Sr concentrations reduction to pre-accident levels were made. ► 90Sr CF values for hydrobionts did not depend on distance from the accident area. ► 90Sr is useful as a radiotracer for the chronological dating of the bottom sediments. ► Dose received by hydrobionts from 90Sr after accident period was determined