A NEW TEA BAG INDEX METHOD IN THE STUDY OF IONIZING RADIATION EFFECT ON THE TRANSFORMATION OF PLANT RESIDUES BY MICROOGRANISMS

Abstract

Objective. To study the intensity of decomposition of plant residues in sod-podzolic soils affected with different doses of ionizing radiation in the zone of unconditional (mandatory) resettlement and in the exclusion zone of the Chornobyl Nuclear Power Plant (ChNPP). To assess the prospects of a new method (tea bag index) for determining the features of the transformation of plant residues in the soil. Methods. Radiological (to measure the current level of radioactive contamination in order to justify the selection of territories that have a significant gradient in terms of soil contamination with radionuclides and the rates of absorbed doses of ionizing radiation for soil microorganisms, respectively); tea bag index method, which involves the exposure of standardized tea bags of two types — Lipton green tea (EAN: 87 22700 05552 5) and Lipton rooibos tea (EAN: 87 22700 18843 8) — in soil, followed by measurement of weight loss in a given time; gas chromatography (substrate-induced respiratory method for determining the content of microbial biomass in soil). Results. Relatively low doses of radioactive contamination (up to 1.6 μGy/h) stimulated the accumulation of microbial biomass in the soil of landfill No. 1 (near the village of Khrystynivka, Narodytskyi district, Zhytomyr region) and activated the processes of decomposition of plant residues. High rates of absorbed doses of radioactive contamination (between 3.7 and 61.6 and, especially, for the dose of 84.0 μGy/h) in the soil of landfill No. 2, located in the exclusion zone of the Chornobyl Nuclear Power Plant, had a negative effect on the studied parameters. Conclusion. Low radiation doses activate the development and functioning of soil microorganisms. The negative effect of high doses of ionizing radiation on the activity of soil microbiota, which participates in the transformation of plant residues, persists for a long time (36 years after the Chornobyl accident). At the same time, there is an accumulation of undecomposed dead matter in the soil. The expediency of using the method of determining the activity of transformation of plant residues (TBI) in microbiological studies of soils has been shown, since it is possible to determine not only the rate of mineralization of plant material, but also the parameters of the transformation of residues into stable organic matter de novo.