Relationships between greenhouse gas production and landscape position during short-term permafrost thaw under anaerobic conditions in the Lena Delta
Soils in the permafrost region have acted as carbon sinks for thousands of years. However, as a result of global warming, permafrost soils are thawing and will potentially release more greenhouse gases (GHGs) such as methane (CH 4 ) and carbon dioxide (CO 2 ). To address the large heterogeneities of...
| Main Authors: | , , , , , |
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| Format: | Text |
| Language: | English |
| Published: |
2022
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| Subjects: | |
| Online Access: | https://doi.org/10.5194/bg-2022-122 https://bg.copernicus.org/preprints/bg-2022-122/ |
| Summary: | Soils in the permafrost region have acted as carbon sinks for thousands of years. However, as a result of global warming, permafrost soils are thawing and will potentially release more greenhouse gases (GHGs) such as methane (CH 4 ) and carbon dioxide (CO 2 ). To address the large heterogeneities of GHG releases, this study focused on the relationship between CO 2 and CH 4 emissions and soil parameters, as well as the evolution of microbial abundance during a permafrost thaw experiment representing the extent of an Arctic summer season. Two depths from three Lena Delta cores taken along a transect from upland to floodplain were incubated anoxically for 68 days at two different temperatures (4 °C and 20 °C) and an assessment of microbiological abundance (CH 4 producers and aerobic CH 4 oxidizers) was performed in parallel. Samples from located in upland or slope position remained in a lag phase during the whole incubation, while those from located in the floodplain showed high production of CH 4 (6.5x10 3 µgCH 4 -C.gC -1 ) and CO 2 (6.9x10 3 µgCO 2 -C.gC -1 ). Periodic flooding likely allowed the establishment of favorable methanogenic conditions. The presence of higher copy numbers of methanogenic archaea in the active layer of the floodplain than in the upland and slope from the beginning (1.5 to 9.6 times higher) until the end of the incubation time (11 to 700 times higher) supported this hypothesis. In addition, our study pointed out different anaerobic CO 2 production (methanogenesis and other respiration) pathways according to landscape position. |
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