No abstract

Abstract. Vertical distribution of Cs-137 in cultivated chernozems of the Plavsk radioactive hotspot has been investigated, with the emphasis on the plough horizon. It is shown that the commonly expected complete homogeneity of the isotope vertical distribution within the plough and old-plough horizons of cultivated chernozems is not always achieved. Incomplete homogeneity can be explained by the application of different cultivation techniques for various crops within the crop rotation system employed. Important observation is that in cases of relatively shallow cultivation (such as disking to 12-15 cm depth) the largest root biomass content remains within the upper 10 cm layer, while maximum Cs-137 content is shifted downwards to underplough layer at 10-20 cm depths. At the same time, traditional cultivation with plough layer rotation and mixing to the 20-25 cm depth results in more uniform Cs-137 distribution through the plough layer, while layer of active root uptake of mineral matter for row crops shifts from the soil surface downward. Therefore, it can be recommended that the systematic monitoring of cultivated topsoil conditions based on preliminary assessment of Cs-137 vertical profile distribution, taking into account agrotechnical specifics of different crops within the crop rotation, must be carried out in order to obtain the reliable assessment of the soil radioecological status.

No abstract

Полевые работы выполнены в рамках исследований кафедры радиоэкологии и экотоксикологии факультета почвоведения МГУ имени М.В. Ломоносова "Биогеохимия радионуклидов и экотоксикантов". Элементный состав растений и содержание подвижных форм в почвах определены в рамках проекта РНФ № 17-77-20072. Acknowledgments: Field work was carried out as a part of research by the

On the territory of the Plavsky radioactive hotspot of the Tula region of Russia, formed as a result of the accident at the Chernobyl nuclear power plant in 1986, an assessment of the radiation safety of growing carrots and beets was carried out in 2019. It has been established that at present the content of 137Cs in arable leached chernozems of the surveyed lands is 90–170 kBq/m2 , which is 2.5–4.5 times higher than the permissible level of density of surface radioactive contamination of soils. However, the specific activity of the radionuclide in carrot and beetroot crops does not exceed 5 Bq/kg, which is significantly less than the maximum permissible level of 137Cs accumulation in vegetables (600 Bq/kg for absolutely dry weight). The accumulation coefficients of 137Cs in the total biomass of carrots and beets are 2.0·10−2 and 7.5·10−2, and in eaten root crops – 1.1·10−2 and 2.0·10−2, respectively, which is in good agreement with the IAEA estimate for the intensity of the transition 137Cs in the production of vegetable roots from loamy and clayey soils.