Effect of Drainage on Spatio-Temporal Variation in Water Chemistry of the Great Vasyugan Mire

Abstract

This study assesses spatio-temporal changes in the content of macrocomponents and organic substances in waters of the drained part of the Great Vasyugan Mire in taiga zone of Western Siberia. Studies have shown that the drained area of the Great Vasyugan Mire is characterized by increased concentrations of all components in the chemical composition of its waters compared to the pristine area, with significant differences in the content of Са²⁺, Mg²⁺, Fe_total, ${\text{NH}}_{4}^{ + }$, Cl^–, K⁺, Na⁺, Cl^–, CO₂, and DOC in the waters observed only between individual sampling sites. Cluster analysis confirmed the differences in the chemical composition of waters of the drained and pristine areas of the Great Vasyugan Mire by dividing them into two clusters, with the exception of samples taken in lagg. Due to the overgrowth of ditches, the mire is currently in the process of self-restoration, which results in minimal differences between the chemical compositions of waters of the drained and pristine areas of the Great Vasyugan Mire. It is noted that the chemical composition of waters can vary significantly across the mire area, depending largely on the site’s location relative to water paths and drainage ditches. Factor analysis reveals that the conditions of the formation of the chemical composition of waters also vary across the territory, depending on hydrology and thermal regime of the mire, which are transformed due to drainage and the pyrogenic factor; this results in increased mire water levels contributing to increases in concentrations of Са²⁺, Mg²⁺, Fe_to-tal, ${\text{NH}}_{4}^{ + }$, K⁺, Na⁺, ${\text{HCO}}_{3}^{ - }$, and ${\text{NO}}_{3}^{ - }$ in the waters and their transport out of the mire, which significantly impacts the quality of river waters.