TY  - JOUR
A1  - Tanski, George
A1  - Lantuit, Hugues
A1  - Ruttor, Saskia
A1  - Knoblauch, Christian
A1  - Radosavljevic, Boris
A1  - Strauß, Jens
A1  - Wolter, Juliane
A1  - Irrgang, Anna Maria
A1  - Ramage, Justine Lucille
A1  - Fritz, Michael
T1  - Transformation of terrestrial organic matter along thermokarst-affected permafrost coasts in the Arctic
JF  - The science of the total environment : an international journal for scientific research into the environment and its relationship with man
N2  - The changing climate in the Arctic has a profound impact on permafrost coasts, which are subject to intensified thermokarst formation and erosion. Consequently, terrestrial organic matter (OM) is mobilized and transported into the nearshore zone. Yet, little is known about the fate of mobilized OM before and after entering the ocean. In this study we investigated a retrogressive thaw slump (RTS) on Qikiqtaruk - Herschel Island (Yukon coast, Canada). The RTS was classified into an undisturbed, a disturbed (thermokarst-affected) and a nearshore zone and sampled systematically along transects. Samples were analyzed for total and dissolved organic carbon and nitrogen (TOC, DOC, TN, DN), stable carbon isotopes (delta C-13-TOC, delta C-13-DOC), and dissolved inorganic nitrogen (DIN), which were compared between the zones. C/N-ratios, delta C-13 signatures, and ammonium (NH4-N) concentrations were used as indicators for OM degradation along with biomarkers (n-alkanes, n-fatty adds, n-alcohols). Our results show that OM significantly decreases after disturbance with a TOC and DOC loss of 77 and 55% and a TN and DN loss of 53 and 48%, respectively. C/N-ratios decrease significantly, whereas NH4-N concentrations slightly increase in freshly thawed material. In the nearshore zone, OM contents are comparable to the disturbed zone. We suggest that the strong decrease in OM is caused by initial dilution with melted massive ice and immediate offshore transport via the thaw stream. In the mudpool and thaw stream, OM is subject to degradation, whereas in the slump floor the nitrogen decrease is caused by recolonizing vegetation. Within the nearshore zone of the ocean, heavier portions of OM are directly buried in marine sediments close to shore. We conclude that RTS have profound impacts on coastal environments in the Arctic. They mobilize nutrients from permafrost, substantially decrease OM contents and provide fresh water and nutrients at a point source.
KW  - Canadian Arctic
KW  - Coastal erosion
KW  - Retrogressive thaw slump
KW  - Biogeochemistry
KW  - Carbon degradation
Y1  - 2017
U6  - https://doi.org/10.1016/j.scitotenv.2016.12.152
SN  - 0048-9697
SN  - 1879-1026
VL  - 581
SP  - 434
EP  - 447
PB  - Elsevier Science
CY  - Amsterdam
ER  -