Dissolved and particulate nutrient transport in the Cheboksary Reservoir

Abstract

The reservoirs of the Middle and Lower Volga are prone to eutrophication due to an exceptionally large anthropogenic impact from agricultural, industrial and urbanized areas. To better understand the exact factors driving this process, it is necessary to have accurate data on the nutrient loading of the reservoirs, which comes mostly as river inflow, but there is very little information on the structure of the rivers nutrient budget. Our summer field studies on a sector of the Cheboksary Reservoir from Nizhniy Novgorod to its lacustrine part in 20172019 provided a detailed picture of the dynamics of suspended and dissolved nitrogen and phosphorus and mineral silicon as the Volga River experiences significant hydrological and geochemical changes. The Oka River is shown be the primary supplier of nutrient elements into the reservoir which creates some distinct features of the nutrient regime of an over 100 km long part of the Volga cascade and contributes to a noticeable increase of the main rivers nutrient load.