Radiological situation in the young pine forest that grew after the Chernobyl accident

Abstract

After the Chernobyl accident, a certain proportion of agricultural land was withdrawn from normal use due to significant radioactive contamination. Forestry is one of the options currently under consideration to return the abandoned agricultural land to economic circulation in Russia. When using former agricultural land for forestry in radioactively contaminated areas, it is important to have an assessment of the potential radiation doses for forestry workers and the public. The aim of this study was to assess the radiological situation in a young pine forest planted and grown after the Chernobyl accident in the resettlement zone on a former arable field. A nearby old pine forest, which had grown before the Chernobyl accident, was taken for comparison. The study of the radiological situation was performed in the period 1998–2022. In the young forest, 137Cs was fairly evenly distributed in the upper 20 cm soil layer; further with depth, the activity concentration of 137Cs sharply decreased. In the old forest, the maximum activity concentration of 137Cs in the soil was in the top 0–2 cm layer. The activity concentration of 137Cs decreased with depth. In 1998, the average value of the absorbed dose rate in the air from 137Cs+134Cs was lower by a factor of 3 in the young forest compared to the old forest. The difference was associated with differences in the vertical distributions of 137Cs in the soil. Over time, the absorbed dose rate in air from 137Cs+134Cs decreased at both sites with the same effective halftime period of 21.7 year. The activity concentration of 137Cs in the biota (pine trees, edible mushrooms) in the young forest was lower by a factor of 4–30 compared to the old forest. The “forest” component of the external effective dose to adults from the 137Cs source in the young forest was lower by a factor of 3 compared to the old forest. The “forest” component of the internal effective dose from 137Cs was lower by a factor of 10 when eating edible mushrooms from the young forest compared to the old one. In general, the performed study shows that the use of radioactively contaminated abandoned arable land for forestry can be expedient and justified from a radiological point of view.