Concentration of biogenic elements, fluorescent characteristics, and direction of СО2 fluxes over the water area of Lake Baikal in the spring periods of 2016 and 2017

This study continues the thorough investigation of the impact of physical, hydrological, chemical, and biological processes on the СО2 gas exchange in the water-atmosphere system at Lake Baikal. The results of measurements of the СО2 flux direction, biogenic elements, and fluorescent characteristics over the entire Baikal territory in the spring periods of 2016 (from 25.05 to 06.06.) and 2017 (25.05 to 05.06) are compared. Fluorescent characteristics were measured with a flow-through fluorimeter, whose operation is based on the principle of pulse-amplitude modulation. It is shown that most significant year-to-year differences in the analyzed characteristics are observed in the Middle Baikal region. In 2016, the surface temperature in this zone approaches 40°C, and probably the vertical exchange process manifests itself here.