Summer surface water chemistry dynamics in different landscape units from Yedoma Ice Complex to the Lena River


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Anne.Morgenstern [ at ] awi.de

Abstract

About 25 % of the land mass of northern hemisphere is underlain by permafrost, which is one of the largest carbon pools. Yedoma Ice Complex is a particularly ice-rich type of permafrost. As a consequence of rapid climate warming of the Arctic, permafrost is affected by degradation processes like thermokarst. Thereby organic carbon is partially dissolved (DOC) in thermokarst lakes, and transported via rivers into the Arctic Ocean. On this way, large parts of DOC are mineralized by microbial processes and emitted as CO2 and CH4 to the atmosphere. The influence of different landforms in thermokarst affected permafrost regions on DOC concentration has not been thoroughly investigated. Addressing this research gap, this thesis examined the relationship between landscape units, water chemistry and hydrology for a small study site in the Lena River Delta, Siberia. On the basis of GeoEye satellite imagery eight landscape units were determined. These include thermokarst lakes and streams on the first terrace and on Yedoma Ice Complex, Yedoma Ice Complex streams, which are fed by the Ice Complex, Yedoma Ice Complex uplands, first terrace relict lake, and the Olenyokskaya Channel. Concerning pH value, electrical conductivity, isotopic composition and DOC concentration summer surface water samples and soil water samples of 2013 and 2014 were analyzed. These analyzes revealed that the system of the thermokarst lake Lucky Lake, its drainage flow path and source waters on Yedoma Ice Complex, is divided by landscape units. Source waters show significantly higher DOC concentrations and lower electrical conductivity than Lucky Lake and the drainage flow path. This suggests that labile organic carbon of Yedoma Ice Complex reaches the lake by degradation. Yedoma Ice Complex lake processes, despite evaporation, further reduce DOC concentration rapidly, probably by mineralization of labile DOC. Along the drainage flow path no further decrease of DOC concentration was observed, despite of changing discharge. Using discharge data of 2013 a DOC flux of about 220 kg in 29 days for the study site was calculated. A temporal variability of DOC concentration during the sampling periods was not determined using the utilized data.



Item Type
Thesis (Master)
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Peer revision
Not peer-reviewed
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Published
Eprint ID
39226
Cite as
Polakowski, L. (2015): Summer surface water chemistry dynamics in different landscape units from Yedoma Ice Complex to the Lena River , Master thesis, University of Potsdam.


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