The changing Arctic Freshwater System: The Biogeochemistry of Small Arctic Coastal Catchments
The Arctic freshwater systems plays a key role in storing and delivering sediments, organic matter and solutes downstreams to the Arctic Ocean. Climate change has led to drastic changes in the freshwater cycle, which is reflected in increased discharge and biochemical fluxes from the six large Arcti...
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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/50468/ https://hdl.handle.net/10013/epic.9e5be4b0-b0cc-4b11-8231-c34048144383 |
| Summary: | The Arctic freshwater systems plays a key role in storing and delivering sediments, organic matter and solutes downstreams to the Arctic Ocean. Climate change has led to drastic changes in the freshwater cycle, which is reflected in increased discharge and biochemical fluxes from the six large Arctic rivers coering approximately half of the Arctic drainage basin. Scaling the results to the unmonitored portion f the pan-Arctic watershed is difficult as these smaller catchments do not extend as far south and cover differing climae, permafrost and vegetation zones. Further, permafrost degradation processes, like the in situ thawing of permafrost and the occurence of physical disturbances have effects on the freshwater quality. The overall aim of this thesis was to understand biogeochemical characteristics and lateral flixes from small Arctic coastal catchments with respect to summer rainfall and permafrost degradation. Specifically, the objectives were (1) to investigate downstream changes in biogeochemistry with regard to past and present permafrost degradation in a Low Arctic setiing, (2) to assess downstream changes in dissolved organic matter (DOM) quality in different geiographic settings (Low Arctic and High Arctic) and (3) to quantify biogeochemical fluxes from a Low Arctic catchment over several summer seasons. Information on past and present permafrost degradation at Herschel Island (Yukon, Canada) was obtained by mapping physical disturbances (active layer detachment slides ALDS and retrogressive thaw slumps RTS) from aerial photographs and satellite imagery. This revealed a decrease in the total area of disturbances by 41 % and an increase of number of disturbances by 66 % between 1952 and 2015. The geospatial information of the disturbances was then linked to stream biochemistry. Hydrological connectivity of disturbances was essential to impact solute and suspend sediment concentrations from slopes, tributaries and along the stream. Degrading ice-wedge polygons were found to substantially alter the ... |
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