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Dr. Yu.A. Ilyevsky, Prof. T.I. Drobasheva, S.V.Rastoropov M.Sc.

Control of Pollution by Heavy Metals and Its Significance in Ecology of the Don River Lower Reaches

The problem of water purity in the Don delta has become aggravated in the course of the last years as a result of techno-genealogical chemical pollution of drain faults and application of imperfect technologies, accumulation of solid waste, rock dumps, etc. Agriculture has undergone qualitative changes thanks to soil melioration development. Among the most significant components causing biosphere pollution are those of heavy metals deteriorating the hydro-geochemical natural balance and the conditions of human life. These are copper, zinc, cadmium, lead, nickel, chromium, tin, manganese and other toxicants. Processing and repeated use of waste of these metals are not sufficient enough for the time being. It must be noted that in Israel proposals have been elaborated aiming at search for possible users of heavy metals waste and its realization through the “waste commodity exchange”. Information related to waste materials and their components will be computerized and made available for publication. Burying of waste not liable to processing must meet the requirements of environment protection. Still, special attention in this direction must be paid to search for up-to-date rational technologies without waste and for diminishing of waste and of its diversity.

To a considerable extent the above relates to eco-chemistry of the Don lower reaches and to Rostov-on-Don, the major southern populated center of Russia. The Don river, above one thousand kilometers long, flows out of the Tzimlyan storage lake in the Rostov direction. The main indices of the Done lower reaches chemical composition are formed in this reservoir, as well as caused by influence of its tributaries, including Temernik for the zone of Rostov. In the course of the last decades the capability of self-purification of Don has been heavily reduced as a result of the influence exerted by the Don silt containing large amount of heavy metals. The upper horizon of Rostov soils contains considerable admixtures of vanadium, chromium, zinc, lead. Don is an important source of drinking water and irrigation, but for the time of being the river is being reconstructed as a kind of navigable canal from Volgodonsk to Azov. Its navigation function is being developed as preferring that of being the source of drinking water and fish. The river became shallow, its regular purification by means of earthly gears prevents balance normalization of components related to the hydro-chemical regime and causes a considerable damage to ecology of the Southern region.

Quantitative evaluation of the impact exerted by ions of heavy metals on the water structure is implemented in the process of years of monitoring in fixed sections of the Don river and of Temernik using methods of nuclear-absorbing spectroscopy, photo-color-metrics, photo-metrics. Comparison with the maximum permissible concentration of drinking water enabled to detect the most polluted places of the reservoirs deteriorating the water quality of the Don river. We accomplished generalization of data related to chemical analysis of ions of heavy metals in the water of the Don river and of Temernik, as compared with nearby reservoirs, aiming at exposure of the most dangerous “hearths of influence” on water quality during the period of 2000-2009. The analysis included content of ions Fe (general), Cu2+, Zn2+, Ni2+, Pb2+, Cr (general), Cd2+, Mn2+. The most polluted places were detected in the Temernik river outfall (in mg/l) with Pb2+ (0.018), Ni2+ (0.05), Cu2+ (0.04), Zn2+ (0.08). In the Don river (streets 29-35, Rostov line) the data detected (in mg/l) were Ni2+ (0.04), Cu2+ (0.08), Zn2+ (0.04), Mn2+ (0.03). In 2008-2009 the average annual concentrations of heavy metals in the Don river near Rostov diminished 1.4-1.9 times. The control proceeded at the Research Institute in 2009 as related to the state of fishery reservoirs in the Don outfalls, and it indicated that the content of priority toxicants, heavy metals in water, in most cases is at the level or less as compared with 2005-2008 data. Exceeding of maximum permissible concentration in samples for Cu2+ was 39% (spring), 72% (summer), 56% (autumn), for Mn2+ 61% (spring). These values are much higher than those of maximum permissible concentration of fishery reservoirs.

What causes the maximum pollution is the region of the autumn Temernik river lower reaches near the drainage slope of industrial enterprises and the “Severnaya” sewerage pumping station, which need a system of local revolving processing of sewage. Solution of problems related to centralized purification in Rostov is being carried out since the early 2000-ies due to “Purposeful ecologic program” of the Temernik river sanitation in several stages. The first stage has been actually completed: a concrete canal in the river lower reaches has been poured. Further implementation of the program is hampered by municipal drains of galvanic departments and enterprises of techno-chemical profile.

Purification of drainage containing copper, zinc, nickel, cadmium, chromium and other metals is mainly implemented by methods of aeration, chemic-reagent processing, though these methods are not widely applied.

One of perspective methods of heavy metals removal from water solutions for the Southern region is that of use of carbonate containing sewerage, such as slag from thermal power stations and other enterprises. In researches of Dr. Ye.M.Bayan with co-authors (2004) a method was tested to utilize waste of the Rostov Thermal Power Station No.2 for the purpose of sour solutions neutralization and excretion of five ions Cu2+, Zn2+, Ni2+, Fe3+, Cr3+ by the method of precipitation. Due to activity of slag basically containing carbonates Ca, Mg, hydroxides Fe, Al and silica, ions comprise the series Cu2+> Zn2+ > Fe3+ > Cr3+ > Ni2+.

As stated above, quality of water processing in Rostov and in the entire district constitutes quite an acute and urgent problem. A series of important measures were undertaken and outlined for further implementation in the Russian Federation Program up to 2020. In 2012 in Rostov a station of ultra-violet disinfection was established to provide purification of the Water Canal sewage disposal constructions in the Alexandrovsky region. A complex “Dugino” with overflow and water purification is being constructed in Rostov suburb, which will reduce deficiency of drinking water and raise its quality. This complex program is being realized on the basis of the Rostov Water Canal, member of a group of companies within the Open Stock Corporation “European” having wide experience in establishment of systems of public constructions.