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THE INFLUENCE OF LONG-TERM CHEMICAL CONTAMINATION IN THE ZONE OF SEDIMENT PONDS ON BIOGEOCHEMICAL AND MORPHOLOGO-ANATOMICAL CHARACTERISTICS OF SOILS AND PLANTS

Victor Chaplygin

Abstract

The high level of environmental ?ontamination is a stress factor for plants, which causes an integrated nonspecific response aimed at the survival of biosystems due to the formation of protecting mechanisms. The effect of long-term chemical contamination of soils on the growth and structure of reed (Phragmites australis Cav.) roots and stems has been investigated. Soils and plants on monitoring plots in the zone of sediment ponds of chemical plants were studied. The area under study is located in the Severskii Donets River floodplain, Kamenskii district of Rostov oblast, southern Russia (48В°20?42.15" N, 40В°14?14.46" E). The contents of total heavy metals were determined by the X-ray fluorescence method. Heavy metals in plants were prepared for analysis by the dry ashing method at 450 В°C. The optical observations were carried out in a Mikmed-6 microscope. Polyelement ?ontamination of soils on the studied monitoring plots was revealed, with exceedances of lithosphere clarks in hundreds of times for Zn and Cd, in tens of times for Pb, and in several times for Cu, Ni, Cr, and Mn. An ecological-geochemical estimation revealed an extremely hazardous level of soil contamination with total metals. It is shown that the high level of soil contamination decelerates the ontogenetic development of plants and decreases their morphometric parameters. It is suggested that the revealed structural changes in epidermis and mesoderm under the impact of metals hamper the radial migration of fluid in the root from the peripheral parts. These changes are one of the reasons for the decrease in the level of nutrient uptake and translocation from roots to shoots.

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