Water quality monitoring of the Angara River source

Abstract

Studies of the Angara River source from March 2017 to April 2020 provided monthly monitoring of the quality of the waters in Lake Baikal. The monitoring of the water from the Angara source based on hygiene indicator bacteria indicated its correspondence to the standards for the quality assessment of the surface waters, except for two samples taken in May 2018 and July 2019 (exceeding number of enterococci). The data on the number of the hygiene indicator microorganisms for the Angara source were generally comparable to the results of the investigations of pelagic samples from the lake and significantly lower than the values for the main tributaries of the lake. The monitoring revealed the number of psychrophilic bacteria was mainly equal to or higher than organotrophic, except for the warmest month, August, when their number was two-three times lower. Peaks exceeding the number of the studied groups of microorganisms by two-three orders of magnitude were observed in December 2018 as well as in February and August 2019. In macro- and microchemical composition, the samples of the water from the Angara source corresponded to the requirements for the drinking water quality.