Publications by authors named "Nikita Tananaev"
Climate change affects more than elsewhere the northern circumpolar permafrost region. This zone comprises large rivers flowing mainly to the Arctic Ocean, delivering about 10 % of the global riverine water flux. These pan-Arctic Rivers drive the dynamics of northern organic carbon (OC) and mercury (Hg) cycling.
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- Methane-cycling is increasingly important in high-latitude ecosystems as global warming releases more organic carbon from permafrost, leading to the study of 387 samples from regions like Siberia, Alaska, and Patagonia.
- The research integrated physicochemical, climatic, and geographic data with microbial genetic sequences to analyze the structure of methane-related microbial communities, showing that pH significantly influences community composition.
- Key bioindicator taxa associated with different ecological conditions were identified, such as Methanoregula as generalist methanogens and specific methanotrophs like Methylocystis and Methylobacter, highlighting their role in understanding methane cycling and its impact on greenhouse gas emissions under climate change.
High latitudes are experiencing intense ecosystem changes with climate warming. The underlying methane (CH) cycling dynamics remain unresolved, despite its crucial climatic feedback. Atmospheric CH emissions are heterogeneous, resulting from local geochemical drivers, global climatic factors, and microbial production/consumption balance.
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- During Arctic spring, halogen radicals oxidize elemental mercury, which is then deposited to the cryosphere, leading to increased mercury levels in the atmosphere during summer.
- The study tracks mercury isotope variability and finds that the summer peak in mercury levels mainly consists of re-emission from spring deposits, rather than significant contributions from terrestrial sources.
- The research suggests that while terrestrial mercury inputs are significant, they primarily remain within the marine ecosystem of the Arctic Ocean, potentially impacting local food webs rather than contributing greatly to global atmospheric mercury levels.
Arctic lakes emit methane (CH) to the atmosphere. The magnitude of this flux could increase with permafrost thaw but might also be mitigated by microbial CH oxidation. Methane oxidation in oxic water has been extensively studied, while the contribution of anaerobic oxidation of methane (AOM) to CH mitigation is not fully understood.
View Article and Find Full Text PDFIt is commonly assumed that methane (CH) released by lakes into the atmosphere is mainly produced in anoxic sediment and transported by diffusion or ebullition through the water column to the surface of the lake. In contrast to that prevailing idea, it has been gradually established that the epilimnetic CH does not originate exclusively from sediments but is also locally produced or laterally transported from the littoral zone. Therefore, CH cycling in the epilimnion and the hypolimnion might not be as closely linked as previously thought.
View Article and Find Full Text PDFPermafrost peatlands are important carbon stocks currently experiencing rapid evolution after permafrost thaw. Following thaw, dissolved organic matter (DOM) is a potentially important pathway for the release of permafrost carbon. This study investigates the origin and composition of DOM across sites at different stages of thaw in a discontinuous permafrost area of North Siberia.
View Article and Find Full Text PDFMidlatitude anthropogenic mercury (Hg) emissions and discharge reach the Arctic Ocean (AO) by atmospheric and oceanic transport. Recent studies suggest that Arctic river Hg inputs have been a potentially overlooked source of Hg to the AO. Observations on Hg in Eurasian rivers, which represent 80% of freshwater inputs to the AO, are quasi-inexistent, however, putting firm understanding of the Arctic Hg cycle on hold.
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