Features of the long-term dynamics of hydrochemical indicators of the Lower Volga reservoirs and the Ural River (on the example of the Saratov, Volgograd, Iriklinsky reservoirs)

The article considers the long-term dynamics of organic matter, biogenic and toxic elements in the reservoirs of the Lower Volga (Saratov and Volgograd) and the Ural River (Iriklinskoe), differing in geographical location, morphometric and hydrological characteristics. In the Ural reservoir, in contrast to the Lower Volga reservoirs, lower concentrations of mineral nitrogen, silicon, as well as indicators characterizing allochtonic organic matter, and a higher level of total and easily oxidable organic matter are recorded. There are differences in the seasonal and spatial dynamics of the ingredients. Despite the differences in the hydrochemical regime of the reservoirs under study, the synchronicity of the main indicators characterizing the trophic status of the aquatic ecosystem (total, easily oxidable and allochthonic organic matter, and nitrate nitrogen), as well as the amount of water flow through the corresponding hydroelectric facilities was revealed. Studies of the structure of a multidimensional array of general hydro/chemical indicators by the method of principal components revealed the universality of the processes occurring in reservoir ecosystems, the basis of which is surface runoff and seasonal changes.