An availibility of arctic lakes organic sediments to microbial degradation: a laboratory incubation experiment

• Published in: Arctic and Antarctic Research
• Main Authors: N. K. Alekseeva, S. Yu. Evgrafova, A. E. Detsura, A. V. Guzeva, M. K. Meteleva, I. V. Fedorova, Н. К. Алексеева, С. Ю. Евграфова, А. Е. Децура, А. В. Гузева, М. К. Метелева, И. В. Федорова
• Other Authors: The authors have no competing interests. Funding. The study was funded by RFBR, project number 19-34-50086 “Mobility” and by RFBR, project number 18-05-60291 “Adaptation of the Arctic limnosystems to rapid climate change”., Работа выполнена при поддержке гранта РФФИ № 19-34-50086 «Мобильность» и РФФИ № 18-05-60291 «Адаптация арктических лимносистем к быстрому изменению климата».
• Format: Article in Journal/Newspaper
• Language: Russian
• Published: Государственный научный центр Российской Федерации Арктический и антарктический научно-исследовательский институт 2021
• Subjects: термокарстовые озера; carbon dioxide; incubation experiments; methane; oxbow lakes; sediments; stable carbon isotopes; thermokarst lakes; донные отложения; инкубационные эксперименты; метан; углекислый газ; стабильные изотопы углерода; старичные озера; Arctic; lena river; permafrost; Polarforschung; The Cryosphere; Thermokarst; термокарст*
• Online Access: https://www.aaresearch.science/jour/article/view/342; https://doi.org/10.30758/0555-2648-2021-67-1-100-121

The water ecosystems of the Arctic region are most vulnerable to modern climatic changes since the global biogeochemical processes mostly occur on the territories of the permafrost zone. Aquatic ecosystems show a high degree of sensitivity to climatic changes; both in these and in other ecosystems, the biogeochemical processes are intense. These water bodies are located in the permafrost zone, which is vulnerable to temperature increases. The paper gives new insights into the fundamental research question of how fast the organic matter of thawing permafrost can be converted to greenhouse gases emitted into the atmosphere (CO2, CH4). We aimed to assess the microbial response and the associated release of CO2 and CH4 from the Arctic lakes in response to temperature increase. We investigated lakes located in the Lena River delta in the Samoylov Island, Russia, at 72° 22′ N, 126° 28′ E. Bottom sediments from three thermokarst and three oxbow lakes were anaerobically incubated in the laboratory at two temperature regimes (at 4 °C and at 25 °C). All the oxbow lakes have shown similar dynamics of methane emission both at low temperatures (4 °C) and at high temperatures (25 °C). The shift of carbon isotopic composition in methane has indicated that methane is emitted in all the oxbow lakes with a similar composition of microbial communities. In the thermokarst lakes, the emission of methane in the sediments proceeded differently at low and at high temperatures. These results have indicated a dissimilar composition of methanogenic / methanotrophic populations in the thermokarst and oxbow lakes. In both cases, the temperature increase caused a growth in methane emission from the sediments of the Arctic lakes. The thermokarst lakes will make a greater contribution to methane emission than the oxbow lakes. Thus, it is believed that the emission of methane from the thermokarst lakes will rise from 6 to 46 times due to ambient temperature increase. Methane emission from the oxbow lakes will grow from 1.8 to 7.6 times. Our ...