Human impact on organic matter distribution in the Moskva River

Abstract

In 2019, we conducted an integrated study on the Moskva River and its tributaries during the low summer season with a focus on organic matter content (OM) assessment in river waters. The maximum OM content was measured at the river headwaters and related to natural sources. The Mozhaysk Reservoir regulation in the summer had the effect of increased organic load below the dam due to a rise in the allochthonous labile OM. Upstream from the Moscow City, the OM content was relatively low, despite wastewater inflow from several densely populated areas and polluted river inflow. Within the city, organic matter concentration increased by a factor of 1.5 due to an inflow from the Volga River via the Moskva-Volga Canal, whereas the release of treated sewage from the Moscow City wastewater treatment facilities did not have a significant effect. Below the city, the OM content increased again by a factor of 1.5 due to the inflow of urban and industrial wastewater and polluted tributaries. The observations in the lower reaches of the Moskva River indicate a high degree of anthropogenic euthrophication.