Nitrogen and Phosphorus in the Central Zone of the Arakhley Lake

Abstract

The aim is to show changes in the content of biogenic elements (nitrogen and phosphorus) in the Arakhley Lake, observed during the field research from 2017 to 2019. The Arakhley Lake is located in the Eastern part of the Vitim plateau on the watershed of the Vitim and the Selenga rivers, in the area featuring a sharply continental climate. The Arakhley Lake belongs to the system of the Ivano-Arakhleysky Lakes. Materials and methods. Standard hydrochemical methods and GOST were used in sampling and analysis. The studies were carried out using a Spekol-1300 spectrophotometer. Results and discussion. In 2018, as compared to the findings of 2017 and 2019, the concentration of biogenic elements in the Arakhley Lake increased due to the increase in precipitation in the summer. The oxidability of organic matter in surface waters features significant and fairly regular fluctuations detected over a year and during a long-term period. Those are determined by the change in time and mineralization of both allochthonous and autochthonous organic matter accumulated in the reservoir. Conclusions. The research has shown that the increase nitrate ions, phosphates and total phosphorus is associated with heavy precipitation, which caused an increase in the intake of allochthonous organic matter. Biogenic elements are mostly within the normal range of MPCr/h. The content of organic matter showed no significant changes over the entire study period (2017-2019).