1Winogradsky Institute of Microbiology and Institute of Bioengineering, Research Centre of Biotechnology of the Russian Academy of Sciences, Moscow, 119071, Russia
2Peoples' Friendship University of Russia, Moscow, 117198, Russia
3Earth Cryosphere Institute of Tyumen Scientific Centre, Siberian Branch, Russian Academy of Sciences, Tyumen, 625000, Russia
4Institute of Earth Sciences, Saint-Petersburg State University, Saint-Petersburg, 199034, Russia
5Otto-Schmidt Laboratory of Arctic and Antarctic Research Institute, Saint-Petersburg, 199397, Russia
6University of Tyumen, International Institute of Cryology and Cryosophy, Tyumen, 625003, Russia
1Winogradsky Institute of Microbiology and Institute of Bioengineering, Research Centre of Biotechnology of the Russian Academy of Sciences, Moscow, 119071, Russia
2Peoples' Friendship University of Russia, Moscow, 117198, Russia
3Earth Cryosphere Institute of Tyumen Scientific Centre, Siberian Branch, Russian Academy of Sciences, Tyumen, 625000, Russia
4Institute of Earth Sciences, Saint-Petersburg State University, Saint-Petersburg, 199034, Russia
5Otto-Schmidt Laboratory of Arctic and Antarctic Research Institute, Saint-Petersburg, 199397, Russia
6University of Tyumen, International Institute of Cryology and Cryosophy, Tyumen, 625003, Russia
Received: 22 Aug 2020 – Accepted for review: 02 Oct 2020 – Discussion started: 30 Oct 2020
Abstract. Microbiological, molecular ecological, biogeochemical, and isotope geochemical research was carried out in four lakes of the central part of the Yamal Peninsula in the area of continuous permafrost. Two of them were large (73.6 and 118.6 ha) and deep (up to 10.6 and 12.3 m) mature lakes embedded into all geomorphological levels of the peninsula, and two others were smaller (3.2 and 4.2 ha) shallow (up to 2.3 and 1.8 m) lakes which appeared as a result of thermokarst on constitutional (segregated) ground ice. We collected samples in August 2019. The Yamal tundra lakes exhibited high phytoplankton production (340–1200 mg C m−2 day−1) during the short summer season. Allochthonous and autochthonous, both particulate and dissolved organic matter was deposited to the bottom sediments, where methane production occurred due to anaerobic degradation (90–1000 µmol СН4 dm−3). The rates of hydrogenotrophic methanogenesis appeared to be higher in the sediments of deep lakes than in those of the shallow ones. In the sediments of all lakes, Methanoregula and Methanosaeta were predominant components of the archaeal methanogenic community. Methane oxidation (1.4–9.9 µmol dm−3 day−1) occurred in the upper sediment layers simultaneously with methanogenesis. Methylobacter tundripaludum (family Methylococcaceae) predominated in the methanotrophic community of the sediments and the water column. The activity of methanotrophic bacteria in deep mature lakes resulted in a decrease of the dissolved methane concentration in lake water from 0.8–4.1 µmol CH4 L−1 to 0.4 µmol CH4 L−1, while in shallow thermokarst lakes the geochemical effect of methanotrophs was much less pronounced. Thus, only small shallow Yamal lakes may contribute significantly to the overall diffusive methane emissions from the water surface during the warm summer season. The water column of large deep lakes on Yamal acts, however, as a microbial filter preventing methane emission into the atmosphere.
Microbial processes of the methane cycle were studied in four lakes of the central part of the Yamal Peninsula in the area of continuous permafrost, two large, deep lakes and two small and shallow ones. It was found that only small shallow contributed significantly to the overall diffusive methane emissions from the water surface during the warm summer season. The water column of large deep lakes on Yamal acted as a microbial filter preventing methane emission into the atmosphere.
Microbial processes of the methane cycle were studied in four lakes of the central part of the...
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