The Behavior of 90Sr in Macrophytes Inhibiting Water Reservoirs in the Belarussian Sector of the Chernobyl NPP Exclusion Zone

Abstract

Closed and weakly flowing water bodies in the Belarusian sector of the exclusion zone of Chernobyl accident contain high concentrations of radioisotopes. Macrophytes often are the main components of the water ecosystem in terms of biomass and can actively accumulate radioisotopes, playing an important role in the redistribution of radioactive isotopes between the elements of the reservoir. The main objects of the investigation in the exclusion zone of Chernobyl accident was floodplain Lake Prestok, the oxbow of River Pripyat and the Pogonyansky Canal—the channel of the former meliorative canal. The activity concentration of 90Sr in macrophytes depends on the degree of contamination of the reservoir (primarily bottom sediments), the absorptive capacity of the species, season, and growth conditions. It is established that Hidrocharis morsus-ranae L. and Stratiotes aloides L. have an affinity for 90Sr accumulation, irrespective to the ecosystem. Macrophytes rooted at the depth of 1.0–1.5 m (e.g., Phragmites australis Cav., Typha angustifolia L., and Carex sp.) absorb the lowest concentration of radioisotopes. Over the years, the activity concentrations of 137Cs and 90Sr have significant ranges of intraspecific fluctuations and do not follow the general trend towards a decrease in the accumulation of radioisotopes in macrophytes. In most cases, activity concentration of 90Sr in aquatic plants has increased by a little in recent years.