Landscape development and organic matter characteristics of thermokarst lake deposits in Yakutia - Siberia
Withongoing climate warming, Arctic permafrost undergoes fast degradation, resulting inthe deepening of the seasonally unfrozen surface and deep permafrost thaw. As permafrost landscapes store huge amounts of carbon, they are becoming a source of greenhouse gases in the course of remobilization of f...
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| Format: | Thesis |
| Language: | unknown |
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2019
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| Online Access: | https://epic.awi.de/id/eprint/50903/ https://epic.awi.de/id/eprint/50903/1/Landscape_development_and_organic_matter_characteristics_of_thermokarst_lake_deposits_in_Yakutia-Siberia.pdf https://hdl.handle.net/10013/epic.653da8d7-6e9e-43ee-98c5-70ef56447a56 |
| Summary: | Withongoing climate warming, Arctic permafrost undergoes fast degradation, resulting inthe deepening of the seasonally unfrozen surface and deep permafrost thaw. As permafrost landscapes store huge amounts of carbon, they are becoming a source of greenhouse gases in the course of remobilization of former freeze-locked organic carbon. Large regions of the Arctic are coveredby ice-rich silt deposits with huge ice wedges, known as Yedoma. Due to their high ice content,these deposits are explicitly vulnerable to changing environmental conditions. One form of permafrost degradation is the formation of thermokarst lakes. These waterbodies play an important role regarding the thermal energy balance in the ground.Understanding the development of permafrost landscapes and the processes which cause their degradationis essential for the estimation of future changes of the permafrost-carbon feedback. The aim of this study was the reconstruction of the development of athermokarst affected late Quaternary landscape, by analyzing the deposits’ sedimentology to understand past depositional processes. Furthermore, I analysed the organic matter characteristics to identify the vulnerability of the organic carbon. Two sediment cores below two thermokarst lakes in the Lena Aldan interfluve region in Central Yakutia were investigated. One core originates from a Yedoma site (YUK15-YU-L15), where sediments accumulated during the late Pleistocene. The other core was retrievedfromthe bottom of an Alas lake (YUK15-YU-L7), consisting of diagenetically and thermal altered Yedoma deposits. Underneath both lakes, a talik (unfrozen ground or thaw bulb) was present. The talik was about 12 m deep for YUK15-YU-L15 and exceeded the core depth of YUK15-YU-L7. The fieldwork was conducted in March 2015 during a joined German-Russian expedition. The two cores were analysed for hydrochemical, biogeochemical and sedimentological parameters. The grain size distribution shows that the lake deposits of both cores were mainly accumulated by fluvial ... |
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