Assessment of grasslands remediation effectiveness in different periods after the Chernobyl accident

The paper presents the impact of remedial actions on 137Cs content in agricultural lands affected by radiation as a result of the Chernobyl accident. The remediation of 137Cs - contaminated of hayfields and pastures in the vicinity of the Veprin village, located in the Bryansk region, was carried out in 2004. Remediation of greenlands aimed at reduction of soil-forage-milk transfer of 137Cs involved deep ploughing of the soil, liming, introducing high doses of mineral fertilizers and sowing grass mixtures. Evaluation of remedial actions effectiveness after the first three years and 15 years later is discussed in the paper. Undertaken agrotechnical measures resulted in reduction of soil surface layer density contamination with 137Cs by 1.8 times. Due to remediation of the pasture in the river flood-plain the soil surface layer density contamination with 137Cs was reduced by 2.7 times and dose rate by 1.9 times. It is to be noted that lower geomorphological elements of the landscape with prevailing peat soils are critical for accumulation of 137Cs in the grass stand and accumulation of radionuclides in the river floodplain. In the first three years after the remediation 137 Cs soil-grass transfer was reduced by 3 times, and in cultivated hayfield soils the 137Cs transfer was reduced by 8 times. While the land reclamation effectiveness weakened significantly in 15 years after the remediation, accumulation of 137Cs in grass stand grown on cultivated hayfields was 1.6 time lower than in the grass grown in uncultivated lands. The radionuclide content in cultivated pastures is 1.8 times lower than in uncultivated ones. The content of 137Cs in milk was reduced by 3.3 times in the first years after grasslands reclamation, in 15 years the reduction factor was 1.5. Outcomes of long-term follow-up of radioecological situation in grasslands, affected by radiation as a result of the Chernobyl accident, following land remediation and the assessment of its effectiveness can be used as the motivation for and benefits of remedial actions ensuring radiation safety of agricultural products from radioactively contaminated areas. The obtained results can be used for clarification and adjustment of the strategies of reclamation of radioactively contaminated lands and optimal use of grasslands after their restoration.