Bratsk water reservoir is a part of the unified Baikal-Angara water system, the world's largest reservoir of surface drinking water. This study intends to assess the water quality of Bratsk reservoir by examining the spatial and temporal variability of trace element concentrations over periods of changing by the anthropogenic impact. The water samples were collected along the length of the reservoir in 2003, 2008, 2012, and 2018 and analyzed for 12 trace elements (Al, Cr, Mn, Fe, Cu, Zn, As, Cd, Cs, Pb, U, and Hg). The results show that in the zone of maximum anthropogenic impact the concentrations of these elements increased as follows: Al 781.0 µg L⁻¹; Cr 1.43 µg L⁻¹; Fe 1052.4 µg L⁻¹; Cu 3.34 µg L⁻¹; Zn 15.52 µg L⁻¹; Cd 0.691 µg L⁻¹; Cs 0.070 µg L⁻¹; U 1.74 µg L⁻¹; Hg 0.0505 µg L⁻¹. The trace element concentrations in Bratsk reservoir water did not exceed levels set by the international drinking water quality standards. At the same time, the uniqueness of the reservoir requires the use of stricter criteria for water quality control. The trace element concentrations in the water from the source of the Angara river (the only run-off from Lake Baikal) used as reference levels indicate higher levels of metal contamination and pollution indices in Bratsk reservoir water. Over different periods of observation, the contamination factor (CF) showed very high contamination for Al, Mn, Cd, and Cs. PLI indices for 2003 and 2018 classify the majority of water samples as polluted. The NPI values were indicative of severe water contamination by Mn and Pb (all years), Cu (2009), Fe and Cd (2003), Al, Cr, Zn, Cs, and Hg (2003, 2009, 2018). The obtained results showed the importance of using water quality criteria with a view to strengthening the requirements of environmental protection measures in the Baikal region.

布拉茨克水库是全球最大的地表饮用水水库贝加尔—安加拉统一水系统的一部分。这项研究旨在通过研究人为影响而变化的时期内微量元素浓度的时空变化来评估布拉茨克水库的水质。沿水库长度方向分别于2003年，2008年，2012年和2018年收集了水样，并分析了12种微量元素（Al，Cr，Mn，Fe，Cu，Zn，As，Cd，Cs，Pb，U和汞）。结果表明，在最大的人为影响区中，这些元素的浓度增加如下：Al 781.0 µg L ^-1；Al 781.0 µg L ^-1；Al 781.0 µg L ^-1 Cr 1.43 µg L ^-1；Fe 1052.4 µg L ^-1；铜3.34 µg L ^-1；锌15.52 µg L ^-1; 镉0.691μgL ^-1 ; Cs 0.070 µg L ^-1；U 1.74 µg L ^-1；汞0.0505 µg L ^-1。布拉茨克水库水中的微量元素浓度未超过国际饮用水水质标准所设定的水平。同时，水库的独特性要求对水质控制采用更严格的标准。安加拉河水源（贝加尔湖唯一的径流）中水的痕量元素浓度用作参考水平，表明布拉茨克水库水中的金属污染水平和污染指数较高。在观察的不同时期，污染因子（CF）对Al，Mn，Cd和Cs的污染非常高。2003年和2018年的PLI指数将大多数水样品归类为受污染的。NPI值表示锰和铅（所有年份），铜（2009年），铁和镉（2003年），铝，铬，锌，铯和汞（2003年，2009年，2018年）对水的严重污染。