Comparative Analysis of the Chemical Composition of Surface and Groundwater in the Poyang Lake Catchment Area (China).

This paper analyzes data on the chemical composition of wetland waters, groundwaters, and river waters in the catchment area of Poyang Lake, which were obtained in the course of Russian–Chinese hydrogeochemical studies in 2013–2022. The bulk of the laboratory work was carried out at Tomsk Polytechnic University using the mass spectrometric method with inductively coupled plasma. It is shown that wetlands that are not used economically are a source of organic substances and their transformation products entering the groundwater of the upper hydrodynamic zone. An anthropogenic impact on surface and groundwaters has also been established, which manifests itself in a rather sharp increase in the concentrations of certain chemical elements and their compounds. However, at the same time, a significant ability of the region's water bodies to self-purify has been revealed. Thus, in the low-water periods of 2019 and 2022, a decrease in the contents of As, Cd, Ni, Sb, V, Mo, and W in the waters of the Jinjiang River was noted, which is 17–120 times and more just 100–200 m downstream from wastewater outlets. Based on the analysis of measurement results, thermodynamic calculations, mathematical modeling of hydrogeochemical processes, and published materials of other authors, it is concluded that the most likely explanation for this ability is a combination of the following factors: the precipitation of poorly soluble substances (calcium and magnesium humates and carbonates and clay minerals) with the total content of dissolved salts amounting to more than 300–400 mg/dm³; the coprecipitation of a number of microelements, which increases with a decrease in the effective diameter of sediment particles (0.003 mm or less); and the involvement of substances removed from the solution in biogeochemical processes, the intensity of which increases under favorable climatic conditions (such as in the catchment area of Poyang Lake). [ABSTRACT FROM AUTHOR]