MIGRATION OF HEAVY METALS IN ECOSYSTEMS OF THE VOLGO-AKHTUBA FLOODPLAIN BY SEASONS OF THE YEAR
Introduction. The Volga-Akhtuba floodplain (VAP) is a unique natural ecosystem. The presence on its territory of forests, caught meadows, coastal beaches, as well as the diverse flora and fauna determine its high economic value. The main human activity in the floodplain is agricultural. That is why the Volga-Akhtuba floodplain is not an ecosystem, but an agroecosystem.An object. The object of the study is meadow-pasture vegetation and soil in the Volga-Akhtuba interfluve. Materials and methods. In 2018-2019 The influence of spring flood on the ecological state of meadow vegetation of the Volga-Akhtuba interfluve area was monitored at the Federal State Budget Scientific Institution PAFSC RAS. The analysis of vegetation and soil samples for the content of heavy metals depending on the flood. Heavy metals were determined by atomic absorption method on a Hitachi AAS 180-50 spectrophotometer with flame atomization. Results and conclusions. Two-year studies showed that the chemical composition of meadow-pasture vegetation of the Volga-Akhtuba interfluve was influenced by spring floods, which led to a decrease in the concentration of HM. After the flood, the content of HM in vegetation decreased, including manganese and lead, by 1.6 times or by 37.4 and 37.8%, respectively. Analysis of the HM content in the lithosphere showed that after the spring flood, the concentration of lead (by 2.8 times or by 64.6%) of zinc (by 2.3 times or by 55.8%), cobalt (by 2.2 times) significantly decreases or 54.0%) and manganese (1.7 times or 40.0%). The content of other heavy metals in the soil decreases from 1.1 times in nickel to 1.4 times in copper. Then, as in plants, during the summer period, re-contamination of soils occurs and the content of HM in soils returns to its spring values.