Миграция 137Cs в экосистеме поймы р. Унеча

Abstract

Purpose: to study the ¹³⁷Cs migration and concentration in the alluvial soils profile and the radionuclide transfer to plants in the river Unecha floodplain ecosystem. Materials and methods. Field studies were carried out in 2019–2021 in Bryansk region (Klintsovsky district, the village of Lopatni, the right bank of the river Unecha, the current reclamation system). The density of ¹³⁷Cs contamination of the territory after the Chernobyl accident was 185–555 kBq/m². Conjugated soil and plant samples were taken in various sub-systems of the floodplain (near-channel, central, near-terrace). Agrochemical indicators of fer-tility and ¹³⁷Cs specific activity in soil and plants were determined using generally accepted laboratory methods. Results. A strong variability of the agrochemical parameters of alluvial soils in layers every 5 cm within 0–20 cm was determined. A high content of mobile phos-phorus and a low content of potassium, a strongly acid reaction of the environment, and a ten-dency to the growth in the organic carbon content from the near-channel to near-terraсе floodplain subsystem was found. The ¹³⁷Cs horizontal distribution in the river Unecha flood-plain soils was determined by soil genesis of the floodplain subsystems; the maximum specific activity of ¹³⁷Cs 3953 Bq/kg was found in the near-terrace part of the floodplain. The ¹³⁷Cs maximum concentration was found in the near-channel and central subsystem in the soil layer of 0–5 cm, and in the near-terrace subsystem in the layer of 5–10 cm. In the floodplain of the river Unecha, the ¹³⁷Cs coefficient transfer from soil to plants decreases from the central to the near-channel and near-terrace. Conclusions. The formation of agrochemical indicators of al-luvial soil fertility and the ¹³⁷Cs vertical distribution is determined by soil genesis in floodplain subsystems; it can be uniformly decreasing or concentrated in separate layers at biochemical barriers. In the floodplain ecosystem, the ¹³⁷Cs concentration in the 0–20 cm layer increases from the near-channel to near-terrace subsystem. Forage production under the conditions of radioactive contamination of the near-river and central parts of the floodplain is possible without the use of protective measures.