137Cs distribution in the system “agrochernozem clayey-illuvial – potato” in the area of radioactive contamination of the Tula region

Abstract

The features of vertical distribution of 137Cs in the profile of clayeyilluvial agrochernozem, as well as biogenic migration of the radionuclide in the system “soil–plant” of potato agrocenosis have been studied. The research was conducted on the field, occupied by potato variety “Gala”, located in the central part of Plavsky radioactive hotspot of Tula region. It is shown that 35 years after the Chernobyl accident the density of surface radioactive contamination of arable soils in the region exceeds the permissible level by ≈5 times. The depth of 137Cs penetration down the soil profile is mainly determined by methods of agrotechnical soil treatment, and the main part of its inventories is concentrated in the upper 30-cm arable layer. This results in the direct contact of the radionuclide with underground organs of potato (roots, stolons and tubers). However, no more than 0.02% of the total 137Cs inventories contained in the system “agrochernozem–potato” is transferred to potato plants. It was also established that potato plants are characterized by contrasting distribution of 137Cs specific activity values wich varies with organs and tissues. Stolons and thin roots accumulate the radionuclide to the greatest extent per biomass, while tubers, on the contrary, – to the least extent. In general, the levels of 137Cs accumulation in the raw and dry weight of potato tubers, as well as in the products that have undergone culinary processing (boiling the unpeeled and peeled potatoes), correspond to sanitaryhygienic norms, which substantiates the low ecological risks of including potatoes in crop rotations on agricultural land in the area of the Plavsky radioactive hotspot of the Tula region.