ORGANIC MATTER DYNAMICS IN THE WATER OF RESERVOIRS OF DIFFERENT TYPES IN DIFFERENT GEOGRAPHICAL ZONES (PENZA RESERVOIR ON THE SURA RIVER VS. IRIKLINSKY RESERVOIR ON THE URAL RIVER)

Abstract

The organic matter of natural hydroecosystems is an important component determining biological productivity and water quality. The study of the processes of its formation depending on natural and climatic conditions and anthropogenic load is important. Such studies are conducted mainly on lake systems. Meanwhile, the influence of weather and hydrological factors on relatively small multipurpose reservoirs under conditions of significant anthropogenic load makes it possible to note changes in the catchment area within a short period of time. This article presents the results of a 4-year research on organic matter in two artificial multipurpose reservoirs located in different geographical zones. Penza Reservoir (Sura River) is located in the zone of mixed and broad-leaved forests, Iriklinsky Reservoir (Ural River) – in the zone of forest-steppes and steppes. Different climatic conditions determine the content and dominant type of organic matter in each reservoir. The study aims to evaluate seasonal dynamics of organic matter and factors influencing its content. The principal component analysis was used to structure the indicators of allochthonous and autochthonous organic matter based on their predominant genesis. In the Penza Reservoir, which is shallow and well warmed up in the summer, the role of autochthonous humus formed during production processes is great. The seasonal dynamics of allochthonous organic matter are influenced by the volume of runoff during high water, as well as by intra reservoir processes. The continental climate of the Iriklinsky Reservoir basin determines a low amount of precipitation, the main part of which falls on the spring period, when the main proportion of allochthonous substances that are involved in the trophic structure of the reservoir comes from the catchment area, poor in humic substances.