water Article Assessing the Self-Purification Capacity of Surface Waters in Lake Baikal Watershed Mikhail Yu. Semenov 1,*, Yuri M. Semenov 2, Anton V. Silaev 2 and Larisa A. Begunova 3 1 Limnological Institute of Siberian Branch of Russian Academy of Sciences, Ulan-Batorskaya St. 3, 664033 Irkutsk, Russia 2 V.B. Sochava Institute of Geography of Siberian Branch of Russian Academy of Sciences, Ulan-Batorskaya St. 1, 664033 Irkutsk, Russia 3 Irkutsk National Research Technical University, Lermontov St. 83, 664074 Irkutsk, Russia * Correspondence:
[email protected] Received: 9 May 2019; Accepted: 17 July 2019; Published: 20 July 2019 Abstract: The removal of trace metals (TM), dissolved organic carbon (DOC), mineral nitrogen (Nmin.), and polycyclic aromatic hydrocarbons (PAHs) from the water of Lake Baikal and its tributaries was evaluated. The contaminant removal rate (CRR) and the contaminant removal capacity (CRC) were used as water self-purification parameters. The CRR was calculated as the difference between contaminant mass flow rates at downstream and upstream gauging stations. The CRC was calculated as the quotient of the CRR and the change in water discharge between downstream and upstream gauging stations. Whether the CRR and CRC have positive or negative values depends on whether contaminant release or removal occurs in the water body. The CRR depends on the size of the water body. The lowest and the highest CRRs observed for Baikal were equal to 15 mg/s (PAHs) to 7327 g/s − − (DOC), whereas the highest PAH and DOC removal rates observed for Selenga River (the major Baikal tributary) in summer were equal to 9 mg/s and 3190 g/s correspondingly.