Features of the water quality in small rivers of Khabarovsk in winter season
The paper presents the results of studies of the water chemical composition in small rivers of Khabarovsk and its surroundings in the winter low water period in 2017-2018. A significant variation is shown in the concentrations of dissolved substances in river water due to large differences in the composition of underlying rocks, groundwater and wastewater, as well as water of worn-out water supply and sanitation systems. The hydrocarbonate-calcium composition of water, the lowest pH and mineralization values, the phosphate concentrations, as well as the dominance of sulfate ion over chloride and nitrate nitrogen's dominance over ammonium in the river water in the protected areas were identified. The higher content of dissolved substances and the bicarbonate-calcium (sometimes magnesium) composition of water are typical for the rivers in the outskirts of the city, fed mainly by groundwater in alluvial deposits. Hydrocarbonate-sodium (rarely ammonium) composition of water, maximum concentrations of major ions, contamination with phosphates, ammonium nitrogen, petroleum products and surfactants, absence of nitrite and nitrate nitrogen in anaerobic conditions were noted in the river water at the outskirts of the city, which are fed by wastewater. The hydrocarbonate-calcium composition of water, a decrease in the elevated concentrations of major ions during the winter season, pollution with ammonium and nitrite nitrogen, phosphates and oil products of water in the rivers of the central part of the city fed by groundwater and water of worn-out water supply and water disposal systems were established.