Bioindication of mercury pollution in the Bureya Reservoir after the winter landslide
L.M. Kondratyeva, D.V. Andreeva, Z.N. Litvinenko
Section: Monitoring of natural and anthropogenically disturbed areas
In December 2018, at a temperature of -32 оC, a giant landslide with a volume of 24.5 million m3 occurred on the Bureya Reservoir (BR). The landslide triggered tsunami and forest destruction, blocking water access to the Bureya Hydroelectric Power Station. An artificial channel was created as a result of blasting operations. The landslide acted as a biogeochemical barrier and a significant factor affecting water quality due to the water interaction with crushed rock and the influx of large volumes of plant debris and organic matter from the destroyed soil cover. The scale of the impact on the BR ecosystem is difficult to assess without a modern integrated approach based on a combination of biological and physicochemical methods. In the summer of 2022, ecological studies in situ and in vitro using microbiological and spectral methods were conducted on the BR. Microbial complexes and individual strains of cultured heterotrophic bacteria isolated from different habitats (surface and bottom water layers; bays filled with wood) served as bioindication objects of the BR state at the research sites. 62 bacterial strains were isolated from water samples in the landslide-affected zone. About 50 % of the strains were Hg-resistant and grew in the presence of 100 mg/L Hg(NO3)2. The strains of sulfatereducing bacteria that were found in bays with floating wood showed maximum resistance to mercury pollution. We use spectrophotometric method (Shimadzu UV-3600) to assess the activity of microbial transformation of the model sodium humate in the presence of mercury. Bacterial strains isolated from bottom water from a depth of 65 m transform the aromatic component of sodium humate into precursors of toxic volatile compounds that contribute methylmercury formation. Sulfate-reducing bacteria with increased Hg-resistance recommended as bioindicators of the long-term environmental risk of mercury pollution in the BR landslide zone.
ISSN 1995-4301
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