Seasonal and Spatial Variability of the Argun River Water Chemical Composition

The article discusses seasonal and spatial variability of the chemical composition of the waters of the Argun River which is the right component of the Amur river according to the Transbaikal AHEM (1962–1975 and 2016–2017), Russian-Chinese monitoring (2008, 2011–2013) and expeditionary observations in June 2018. The maximum concentrations of the main ions, mineral forms of nitrogen, iron compounds and manganese due to a deficiency of dissolved oxygen occurr during the winter low water period mainly in the upper part of the river. During the open channel period, the concentrations of nitrogen mineral forms was below the detection limit, the content of organic substances reaches the lowest values during the summer-autumn low-water period, and the main ions – in rain floods. We found differences in the main ions content along the river length caused by the natural and climatic features of the territory and economic activities in the catchment area. In 2018, observation of the river between Abagatuy and Priargunsk villages established the spatial variability of the main ions concentrations during the summer low water. The highest content of major ions due to mining is typical for the upper part of the river, the smallest – for the part of the river below the confluence of the Ganhe and Derbul rivers, which form the chemical composition on the western spurs of the Greater Khingan Range. An increase in the salt content in the water of the Argun River below the mouths of the rivers Urulyungui, Verkhnyaya Borzya and others draining the steppe and forest-steppe landscapes was noted. Key words: Argun River, water chemical composition, mineralization, main ions, biogenic and organic substances.