Radiation Monitoring in Bryansk Polesie Twenty-One Years after the Chernobyl NPP Accident

E. V. Kvasnikova, S. M. Vakulovskii, S. K. Gordeev, O. M. Zhukova, S. V. Konstantinov, D. A. Manzon, and V. N. Yakhryushin

Bryansk Polesie is the most 137Cs-contaminated region of the Russian Federation after the Chernobyl NPP accident, where in 2007 (i.e., 21 years after the accident), the radiation monitoring was conducted within the Russia–Belarus Union State Program. The paper is based on the comparison of data obtained in the settlements and at the nearby landscape sites outside the villages. The 137Cs content variability in the most spread in Polesie soils, the podzols, is considered using observations obtained at the monitoring sites in Svyatsk and Demenka. It is shown that 137Cs is fixed at the surface, in the upper soil horizons, which is explained by a high soil sorption capacity. Vast crest-sink floodplains with the great contrast range of the hydromorphic features, which cause great variability of the 137Cs vertical distribution, are typical for the Polesie landscape; this fact is confirmed by observations obtained at the monitoring sites located in Starye Bobovichi and Ushcherpie. It is shown that Polesie pine forest contamination maintains higher contamination density levels compared to the nearby settlements, pastures, and meadow lands in the fluvial plains. Extrapolation of the contamination density data obtained within the first decade after the accident as of 2007, performed with allowance for the correction for decay and the comparison of these estimates with the new data accumulated in the recent years, does not show any significant contradiction.