Ecotoxicological assessment of water quality and ecosystem health: a case study of the Volga river / Moiseenko T. I., Gashkina N. A., Sharova Yu. N., Kudryavtseva L. P. // Ecotoxicology and Environmental Safety. - 2008. - Т. 71, № 3. - С. 837-850.

838 T.I. Moiseenko et al. / Ecotoxicology and Environmental Safety 72 (2008) 837-850 Main objectives are as follows: • To identify the levels of contamination of the Volga River water by toxic substances—metals and organic micropollu­ tants. • To study the accumulation of metals in fish as a consequence of increased concentration of metals in the water environment. • To reveal the main pathological manifestations of chronic intoxication in fish of the Volga River. • To assess the ecotoxicological consequences of increased toxic elements in water and the ecosystem health of Volga River on the basis of the pathological investigation of fish. • To discuss critical levels of water pollution, and compare them with existing levels of pollution. 2. M aterials and m ethods In August and September 2000-2002, comprehensive ecotoxicological studies were carried out in 13 sections of the River Volga (Fig. 1): the Ivankovo reservoir (I, II, III) of the Upper Volga; the Gorki (IV, V, VI) and Kuibyshev reservoirs (VII, VIII) in the Middle Volga; and the course (IX, X, XII) and delta (XII, XIII) of the Lower Volga. Water was sampled for determination of the concentrations of toxic substances (metals and toxic organic compounds). Fish were examined to study their physiological state in order to reveal different forms of pathology and organ dysfunction. Water samples were always taken at the precise sites where fish were caught for examination. The bream Abramis brama (L.), the most widespread fish species in the Volga River basin, was used as a bioindicator. It is a benthic fish that does not make long-distance migrations, which enabled the collection of material for examination from limited sections of the river. 2Л. Water chemistry In total, 31 water samples were taken in 13 sections of the Volga River and reservoirs. Water samples were collected into Nalgen® Polyethylene bottles (11 and 60ml). Bottles were cleaned in the laboratory and rinsed twice with lake water before sampling. After sampling, all samples were kept cool (approximately +4°C) in dark containers and were delivered to the laboratory within 1-3 days. The analyses carried out on the water samples were as follows. The pH was measured using a Metrohm®pH-meter; conductivity (20 °C) by Metrohm®- conductivity; alkalinity using the Gran titration method; and natural organic matter content by the Mn oxidation method. Microelement concentrations were determined using the atomic-absorption in graphite furnace method (GFAAS; “Perkin-Elmer-5000” model, HGA-400, AAnalyst-800, Corp., Norwalk, USA). Hg was determined using atomic fluorescence (FI; model Merlin®). Standard solutions with appropriate concentrations for each element were made from 1000 ppm AAS stock standards (Merk, Darmstadt, Germany). In addition, for determination of Hg, Mo, V, Se elemental analysis of the water was carried out by the inductively coupled plasma method using a “Plasma Quad 3” mass-spectrometer manufac­ tured by Fisons Electronic Elemental Analysis (UK). “Acidic” and “alkaline” extractions of the water samples (in glass bottles) were obtained with methylene chloride under field conditions. Concentrations of organic micropollutants in these extracts were determined by gas chromatography using a “QP-5000” chromate-mass-spectrometer manufactured by Shimadzu (Japan). The quality of the analytical results was repeatedly tested by inter­ comparisons during the course of the project (Hovind, 2000, 2002; Makinen et al., 2002 ). Fig. 1. Location of the sections on the Volga River where the investigation was carried out.