Monitoring of 137Cs, 90Sr, and 40K in Gray Forest Soils and Plants of Reference Sites in Vladimir Oblast

—The results of radiation monitoring of gray forest soils of reference agricultural plots of Vladimir oblast, conducted in 2011 and 2016 are presented. The study established background values of specific activities of the studied radionuclides in the soils of reference sites. According to the density of contamination of the arable horizon of soils by 137 Cs and 90 Sr, the level of the ecological situation was determined, which made it possible to attribute the soils of all reference areas of the region to uncontaminated territories suitable without restrictions for agricultural use. The power of the exposure dose of γ radiation of soils and the contribution of 40 K and 137 Cs to the formation of the γ background of soils are established. Correlation analysis determined the influence of the individual physical and chemical properties of soils on the behavior and distribution of radionuclides in the soil and the relationship between the radionuclides themselves. Based on the values of the specific activity of 137 Cs and 90 Sr in plant products grown on the soils of reference sites in 2011 and 2016, rows of cultivated plants were constructed, with a decreasing ability to accumulate these radionuclides from the soil. All plant products grown for all types of crops fully met the sanitary and hygienic standards required to limit the content of 137 Cs and 90 Sr in plant feeds (green mass, straw, and grain) and food products (apples). According to the transition coefficients, it was found that the process of transition of 90 Sr from soil to plants of all kinds proceeded more intensively than the transition of 137 Cs. The calculated coefficients of linear correlation between the values of the specific activity of 137 Cs and 90 Sr in soils and plants revealed the strength and nature of their dependencies.