Dynamics of 137Cs and 90Sr content in the soil cover of agricultural lands in Zhytomyr region

Abstract

The article examines the results of monitoring radionuclide contamination the soils of Zhytomyr region with 137Cs and 90Sr. We summarized the results of agrochemical certification of agricultural land for the period of research in 2006–2020 years (IX–XI rounds). For field and laboratory research, methods of agrochemical certification of agricultural lands and gamma-surveying of the territory and determination of the specific activity of 137Cs and 90Sr in soil samples were used. It was established that during the 36 years that have passed since the accident, the radiation state of the territory of Zhytomyr region has currently stabilized and is formed mainly under the influence of long-lived radionuclides cesium-137 and strontium-90. During the time that passed after the accident, only due to natural radioactive decay, the activity of the isotopes 137Cs and 90Sr decreased approximately by half. This was facilitated by natural processes and the implementation of measures to prevent the removal of radionuclides beyond the exclusion zone. Turf-podzolic soils, which are most common in the Polissia zone, are characterized by high sorption capacity and weak migration along the 137Cs profile. It was established that the number of agricultural lands contaminated with 137Cs and 90Sr with a density <5.0 Ki/km2 and <0.15 Ki/km2 is 99.9% and 99.5%, respectively, the density of land soil contamination in the section of the surveyed areas with 137Cs pollution varied from 0.07 to 3.41 Ki/km2, and 90Sr from 0.013 to 0.164 Ki/km2, therefore, according to current legislation, the soils are considered conditionally clean. A direct correlation between the indicators of the reaction of the soil solution with 137Cs contamination (r=0.94) and a significant correlation with 90Sr contamination (r=0.69) was revealed. A moderate correlation (r=0.40) was found between the indicators of the density of contamination of agricultural land with radionuclides 137Cs and 90Sr. It is emphasized that the use of the land fund of Zhytomyr region requires constant monitoring of soil fertility and contamination with radionuclides. The implementation of the task is possible under the condition of permanent soil and agrochemical monitoring, which is conducted by carrying out agrochemical certification of agricultural lands.