The Pollutants Distribution Types in the Middle and Lower Volga Water and Bottom Sediments

The outcomes of hydro/chemical and soil 1800 km long surveying of the Volga River from Kazan to Astrakhan have been analyzed. Conjugated analysis of the organic (petroleum products, phenols, and pesticides) and non-organic (metals – Cd, Co, Pb, Ni, Zn, Cr, Mn, Fe, Al) pollutants and their proportion in the Middle and Lower Volga (Kuibyshev, Saratov and Volgograd reservoirs) and unregulated part of downstream water and bottom sediments has been carried out. To test a hypothesis on the system interaction of different types of pollutants content distribution in water and bottom sediments their spatially determined comparative assessment has been applied for the first time. Three main types of the pollutants distribution within the“water-bottom sediments” system have been singled out: depositing, transit, and active/passive self-purification types. The “transit” type of metals distribution is typical for Kuibyshev reservoir. It is characterized by the higher metals concentration in water and the absence of their content increase in bottom sediments. Zones of self-purification from metal compounds have been found in water areas of Saratov and Volgograd reservoirs, while depositing zones are typical for the Volga downstream where metals accumulation in sediments have been found. A considerable portion of pesticides and petroleum products supplied to the Volga reservoirs’ ecosystems is accumulated by bottom sediments. The most part of the Middle and Lower Volga water area is a zone of active selfpurification in terms of phenol compounds. It has been shown that when the Volga environmental conditions is assessed the indicators of copper, nickel, as well as iron, manganese, cadmium and petroleum products in bottom sediments are the most informative.