Chemical composition and quality of water of the Selenga River and its tributaries in Mongolia

Abstract

The chemical composition and current state of water quality of the Selenga River and its tributaries in Mongolia are considered in this article based on the hydrochemical studies carried out in July 2013-2014. The observed changes in the chemical composition of the water resulted from natural and anthropogenic factors are analyzed. It is shown that water quality of the Selenga River and its tributaries worsened because of the entering of polluting components from the catchment area of Ulaanbaatar city and its wastewater. No influence of the wastewater from the Erdenet Ore-Dressing Plant (EODP) on the trace elements content in the water of the Orkhon and Selenga Rivers is revealed.

Revealing the Sources of Nutrients in the Surface Waters of the Selenga River Watershed Using Hydrochemical and Geospatial Data

“…It was found that the spatial variability of TON concentrations in the study territory (Figure 6, Table 1) was quite high (it should be noted that the terms "high", "medium" and "low" are based on concentration ranges obtained during this study). It was observed that TON concentrations in the surface waters of the Mongolian part of the Selenga watershed [49][50][51] were much higher than those in waters from the Russian part. This was probably due to lower precipitation and, consequently, lower river runoff in Mongolia (Figure 4).…”

“…The third dataset consisted of literature-derived data on water chemistry in the Mongolian part of the Selenga watershed collected during the period from 2002 to 2015 [49][50][51][52][53][54]. Water samples were collected from the surface in polyethylene bottles.…”

“…However, unlike the high TON concentrations in water, medium TON concentrations seem to be largely caused by natural factors rather than anthropogenic ones. High values (100-200 µg/L) were measured in the surface waters of both the Russian [14,16,43,48] and Mongolian [49][50][51] parts of the watershed. Similar TON concentrations in waters from spatially separated locations, such as the upper (SW 1) and middle (SWs 2 and 3) reaches of the Selenga and the upper reaches of the Orkhon (SWs 4.1 and 4.2), Tuul (SWs 4.5.3, 4.5.2, 4.5.1) and Uda (SWs 9.1 and 9.1.1) rivers, indicated similar mechanisms of formation of the chemical composition of the water.…”