Cytogenetic activity of radionuclide contamination of water reservoirs of the alienation zone of Chornobyl NPP

Abstract

Thirty years after the accident, the alienation zone of Chornobyl NPP continues to be an open source of radionuclide spread which is carried with superficial and soil waters into river systems and moves beyond the area. The study of mutagenic activity of radionuclide contamination of the water reservoirs in the near zone of Chornobyl NNP will make it possible to predict genetic consequences of their effect in the years after the accident. The purpose of this research is to study frequency and spectrum of chromosome aberrations in root meristem cells of Triticum aestivum L. under the prolonged effect of radionuclide contamination of water and bottom deposits of the water reservoirs in the near alienation zone of Chornobyl NPP. Seeds of winter wheat varieties Al’batros odes’kyi and Zymoiarka were sprouted in the conditions of the effect of water radionuclide contamination of the Prypiat River, Brahinka River, a reservoir-cooler of ChNPP, Semyhodskyi backwater, drainage-way 3 of ChNPP, Lakes Hlyboke and Azbuchyn (total specific activity of 137Cs and 90Sr – 0.17–52.99 Bq/м3) and bottom deposits of the left and right banks of Prypiat canal, a reservoir-cooler of ChNPP, drainage-ways 1–3 of ChNPP (total specific activity of 137Cs and 90Sr – 16.0–45.0 Bq/kg). Frequency and spectrum of cytogenetic disorders were identified in the cells of root meristem sprouts with help of the ana-telophase method. Under the influence of radiation on water and bottom deposits of the water reservoirs in the alienation zone of ChNPP, a 1.6–4.2 times increase in the frequency of chromosome aberrations and mitosis disorders was found. The highest levels of cytogenetic activity were shown by water radionuclide contamination in a reservoir-cooler of ChNPP, Semyhodskyi backwater and bottom deposits of drainage-way 2. The correlation between frequency of chromosome aberrations and specific value of radionuclide activity of water reservoirs has not been recorded, which can prove the induction of cytogenetic disorders resulting from the radiation in the low-rate range. The spectrum of cytogenetic disorder types is mostly represented by acentric fragments, bridges and lagging chromosomes. The induction of the cells with lagging chromosomes, which exhibit the highest levels (0.24–0.38%), under the effect of radionuclide contamination of water in Hlyboke Lake, the Brahinka River, the Prypiat River, a reservoir-cooler of ChNPP and bottom deposits of drainage-way 3, allows one to assume the availability of aneugenic factors in the water reservoirs in the alienation zone of ChNPP. The water entities of the alienation zone of ChNPP, the level of radionuclide contamination of which is characterized by a high cytogenetic activity, induce cells with complex chromosome rearrangements of high frequency. Despite the decrease in chromosome aberration frequency effected by the water of the Prypiat River near Chornobyl city, the Brahinka River and bottom deposits of the right bank of Prypiat canal, the increased level of aneugenic cells and the induction of multiple chromosome rearrangements confirm the persistence of mutagenic activity in the abovementioned contaminated water entities.