Long-term cyclicity of trace element in the Baikal aquatic ecosystem (Russia).

Longitudinal monitoring studies (between 2006 and 2019) of the chemical composition of the water from the Angara River source (the runoff of Lake Baikal) revealed the interannual, year-round and monthly cyclicity in the distribution of some trace elements vis-à-vis their concentrations. The change in the concentrations of elements was contingent on the season, the temperature of the air and water, the activity of phyto- and zooplankton and regional changes in the environment (floods, earthquakes, fires, tourism, ships, technogenesis etc.). We compared the concentrations of trace elements present in the water samples from the Angara source and the water samples from Lake Baikal with the maximum permissible concentration values for drinking water. The calculated (median) concentrations for water samples from the Angara source, which spanned the entire study period, were close to the data obtained for the Baikal water.