Water and alluvium of a small river within the urban territory: chemical pollution

The article contains the results of the assessment of chemical pollution in water and bottom sediments of the Tvertsa River across Tver city 2.5-5 km from its influx into the Volga River. The Tvertsa has domestic, drinking, recreational and fishery importance; receives some amount of municipal sewage. Sanitary hygienic standards in water were exceeded slightly: up to 1.5 times in some places by the indicators of biological (BOD5) and chemical (COD) oxygen consumption because of the oxidation of organic substances and 2.7-5 times all over the places by Fe content (from 0.42-0.95 mg / l in the river to 1.53 mg / l in the runoff). Fishery standards are exceeded 1.2-15 times: Fe, Mn, Cu, Co, Ni, petroleum products (PP), suspended substances (S.s), COD and BOD5. The instability in chemical concentrations is largely due to seasonal fluctuations of the water content, including the effects of steady rains. The state of bottom sediments in this section of the river was recorded for the first time. The level of total accumulation (Zc) of metals (Fe, Co, Cu, Ni, Zn, Cd, Mn) and PP was in the “low” category (Zc = 0.8-6.5). The water of the Tvertsa will not have a negative impact on the ecological and sanitary hygienic state of the Volga River. In fisheries the situation may be get worse by the introduction of toxic metals Cu, Co, Ni into the receiving watercourse.