THE CHEMICAL COMPOSITION AND QUALITY OF GROUND WATERS IN THE WATERSHED OF THE GAM AND KAU RIVERS (NORTHERN VIETNAM)

On the basis of the given geochemical research executed in 2010-2014, the general characteristic of the chemical composition and quality of ground waters in the watershed of the Gam and Kau rivers in the territory of Vietnam (Chodon District, Baccan Province, northern Vietnam) is received. The ground waters in the watershed of the Gam and Kau rivers are generally characterized as fresh, hydrocarbonate calcium, subacidic or neutral. In some cases they contain Fe, Zn, Cd, Mn, As, Al, Si in the quantity appreciably exceeding the specifications of the economic-drinking water use established in the Russian Federation and in Vietnam. Features of existential changes of the chemical composition of the ground waters are defined by the geological conditions (deposits of plumbum and zinc and, probably, manganous ores with increased concentration of secondary elements), intraannual distribution of atmospheric humidifying (maxima in July and August) and local environmental contamination in settlements located near the working and closed mountain enterprises. The greatest concentration of trace elements is marked within the limits of the Ban Thi River watershed, perspective from the point of view of carrying out prospecting works, and in the year during rains. At the same time, it is necessary to note that despite a long history of extraction of plumbum-zinc ores on separate sites of the researched territory, the ground water objects possess certain stability in relation to anthropogenous influences and an ability of self-restoration. This ability, the authors believe, is defined, first of all, by the same intensive water exchange in rocks. In turn, the latter is determined by plentiful atmospheric humidifying, significant slopes and filtration properties of grounds, as well as by forest vegetation in the watershed territory that provides for the stability of slopes: these are conditions limiting the area and time of interaction of waters, soils and rocks. The mentioned circumstances are expedient for taking into account when developing mineral deposits, planning and organizing nature protection actions, especially in the basin of the Ban Thi River.