TECHNOGENIC CONTAMINATION OF MEADOW ECOSYSTEMS IN THE SOZH RIVER FLOODPLAIN IN VETKA DISTRICT, GOMEL REGION, 30 YEARS AFTER THE CHERNOBYL CATASTROPHE
The article contains data on technogenic contamination of meadow ecosystems in the river Sozh floodplain in Vetka district, Gomel region, 30 years after the Chernobyl catastrophe. Seven meadow ecosystems were examined. The aim of the research was to assess contamination of meadow ecosystems by cesium-137, strontium-90 and heavy metals. Geobotanical, ecological-floristic, radiological, chemical methods were used in the research. The greatest specific activity of 137Cs was recorded in Deschampsietum cespitosae association and the highest activity of 90Sr was noticed in Junco- Deschamsietum cespitosae association. In the soil the highest level was stated for Fe (312,12 mg/kg) and for Mn (72,22 mg/kg). The minimum was determined for Cd (˂ 0.06 mg / kg); the same amount of Cr was observed in all objects. At the same time, small differences were noted in the accumulation of Co. The content of heavy metals didn’t exceed the maximum permissible concentration of heavy metals in the studied meadow ecosystems soils. The Caricetum gracilis and Phalaridetum arundinaceae plant associations had the highest amount of the aboveground phytomass, namely 3,76 and 3,65 t/ha dry weight, respectively. Accumulation of Co (0,02 mg/kg); Pb (0,03 mg/kg); Cd (0,01 mg/kg); Cr (0,014 mg/kg) in the aboveground phytomass was almost equal in all meadow ecosystems. Plant associations are distinguished by the maximum content of Fe, Cu, Zn, Mn, as well as by the minimum amount. Based on the accumulation coefficient (AC), i.e. the ratio of the amount of heavy metals in the plant to the amount of heavy metals in the soil, the following series of the AC values in decreasing order was established: Zn, Cu, Mn, Fe, Ni, Cd, Cr, Co, Pb. The mean values vary within 0,03-15,4 (mg/kg)/(mg/kg). The maximum AC value was determined for the Caricetum gracilis association.The minimum AC values were stated for Deschampsietum cespitosae, Poo-Festucetum pratensis, Junco-Deschamsietum cespitosae. The highest specific activity for cesium-137 was observed in the aboveground phytomass of the Deschampsietum cespitosae association, for strontium-90 in the Junco-Deschamsietum cespitosae association. The specific activity for cesium-137 in the Deschampsietum cespitosa association was 1439 Bq/kg, and exceeded the Republican permissible level (RDU-99) - 1300 Bq/kg. The specific activity of cesium-137 did not exceed the permissible level of 1300 Bq / kg in other associations. The specific activity of the aboveground mass of all the studied associations for strontium-90 did not exceed the permissible level.