Impact of radioactive contamination of soils on the diversity of micropopulation and the transformation of organic substances

Aim. To study the impact of different levels radioactive contamination on organic matter decomposition and population development microbial decomposers in soil. Methods. Gamma-spectrometry for determination relative activity 137Cs beta-spectrometry 90Sr order to choose range studies; Tea Bag Іndex (TBI), standard glob- ally accepted method determine rate decomposition; gas chromatography – investigated factors formation biomass microorganisms by means СО2 production potential; classic microbiological methods, using elective media estimate densities culturable decomposers. Results. The studies (from April September 2021) comprised two soils with ranges: Range No. 1 Narodychi district Zhytomyr region (the village Khrystynivka, 3 sampling points) unconditional (obligatory) resettlement zone after catastrophe Chornobyl nuclear power plant (ChNPP) (it has an absorbed dose gradient, evaluated soil microorganisms, from 0.2 μGy/h (at point Narodychi-1: 51,24076°N, 29,21497°E) 1.57 Naro- dychi-3: 51,23815°N, 29,22245°E)), located agricultural field, abandoned 2, afforested area, directly bordering territory so-called Red Forest ChNPP ex- clusion (4 points first three natural ecosystems, 4th pyrogenically transformed fires 2020) gradient 3.7 ChEZ-1: 51,38595°N, 30,03035°E) 84.0 ChEZ-4: 51,38231°N, 30,03298°E). dependence studied indicators radionuclides was demonstrated these are conditions that difference is more than 400 times values ionizing radiation rates formed In (on fallow land), increase up μGy/h, there statistically significant mineralization coefficient percentage reduced weight rooibos tea between least most contaminated points), stimulation micromycetes (by 1.2–2.3 times), cellulose-decomposing bacteria 7.1–7.9 ammonifying 1.8–6.3 times) due a increasing number colony-forming units higher radio- nuclide twofold 1.In exclusion zone, characterized low parameters sod-podzolic fertility (humus content 1.2 ± 0.9 0.1 %, exchangeable acidity 4.0 5.0 0.7), one-two orders below indices 1. Micromycetes dominated groups microorganisms. There radionuclide level plots: ChEZ-1, ChEZ-2 ChEZ-3 2. Conclusions. land radia- tion one does not inhibit microorgan- isms soil, rather it stimulates their increases numbers. On poor exclu- sion Chernobyl plant, preponderance over bacterial cellulolytics noticeable. affected biological processes only years catastrophe, which been described literature, but had its influence long time (for thirty accident). Among saccharolytic mode residuals decomposition, dominate.