СРЕДНИЕ ХАРАКТЕРНЫЕ КОНЦЕНТРАЦИИ ТОКСИКАНТОВ В ДОННЫХ ОТЛОЖЕНИЯХ ДЕЛЬТЫ ВОЛГИ И СЕВЕРНОГО КАСПИЯ

Abstract

The general test object in the assessment of pollution degree of water ecosystems are bottom sediments. There are different attempts to norming, having regional status in default of standards of the contents of preferred toxicants in the bottom sediments of water objects at the present time in Russia. In this work scientists used the approach permitting to characterize the pollution degree, using comparison between absolute values of toxicant concentrations, that are most prevailing in the Volga-Caspian basin, and these toxicant concentrations are calculated for each kind of the main type of sediments. For the calculation scientists used longstanding body of data on the content of oil products, zinc, copper, plumbum, cadmium, nickel, manganese and ferrum in the water courses of the Volga Delta and western part of the Northern Caspian. Conducted typification of the grounds with separation of the main types of river and sea sediments was accompanied by averaging out values of toxicant concentrations. There was identified an increase of the content of all toxicants in 2.8-9.8 times when transferring from coarse particle fractions to finely divided fractions for freshwater grounds. In the same time, besides dispersion, the presence of shell material played an important role in the accumulation of oil products, nickel and manganese. In the Northern-Caspian bottom sediments lessening of particle size caused the raise of toxicant concentrations, especially in the presence of silty fractions. Moreover, the growing concentration of several pollutants - nickel, plumbum, and cadmium - was observed in shelly grounds or with impurity of sand. According to the results of comparative analysis of the data on the toxicant content with average specific values in the bottom sediments of watercourses of the Volga delta and the Caspian Sea in 2016, there were singled out the locations most affected by pollution.