Radioecological state of the soil layer of arable lands in Zhytomyr region

Abstract

To determine radionuclide contamination density of the soil layer of arable lands, to set the volume of their areas based on the accepted levels of 137Сs and 90Sr pollution values. Methods: field studies were carried out in accordance with the techniques of agrochemical certification of agricultural lands, gamma surveys of the territory, and determination of the specific activity of 137Сs and 90Sr in soil samples. 137Сs activity was determined by spectrometric method using a SEG-05N instrument with the Progress software, and 90Sr was determined by spectrometric method using an SEB-01 instrument with AK-1 software. During the 29-year post-accident period (1986-2015), the radiation situation of the soil of agricultural land in Zhytomyr region has significantly improved. In 2011–2015 the area of agricultural land of the region with a contamination density of 137Сs from 37 to 185 and from 186 to 555 kBq/m2; for 90Sr — from 0.74 to 5.55 and from 5.56 to 111 kBq/m2 comparing with 2006–2010, has decreased by 1.5 and 0.4% and 36.1 and 2.1%, respectively, with simultaneous growth of areas with contamination density of 137Сs < 37 kBq/m2 by1.9%, and 90Sr <0.74 kBq/m2 by 38.2% or by 1.5 times. The results of studies on the state of agriculture land soil contamination by 90Sr show that currently the territory based on pollution levels is as follows: <0.74 kBq/m2 — 621.4 thousand hectares; from 0.74 to 5.55 kBq/m2 — 213.3 thousand hectares; 5.56 — 111 kBq/m2 — 11.1 thousand hectares, which is respectively 73.5; 25.2 and 1.3% of the total survey area. The areas of agricultural land with 137Сs contamination density <37 kBq/m2 are 89.2%, 37 — 185 kBq/m2 — 10.3% and 186 — 555 kBq/m2 — 0.5% of the surveyed volume, and by density contamination with 90Sr < 0.74 kBq/m2 is 73.5%, 0.74 — 5.55 kBq/m2 — 25.2% and 5.56 — 111 kBq/m2 — 1.3%. It has been established that the decrease in the density of radionuclide contamination in the soil layer of arable land (0–20 cm) is more intense than in other types of agricultural land.