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Title: Hydrological control on carbon fluxes in three subarctic micro-catchments
Author: Ohlanders, Nils Vidar
ISNI:       0000 0004 2740 0231
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2012
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Links between variables such as soil maturity, f1owpaths, water residence time, carbon export and weathering rates need to be further established in order to evaluate the effects of future climatic change on the hydrology and carbon economy of subarctic catchments. Recent studies on post-deglaciation landscape development in the Alaskan Glacier Bay area have suggested that the importance of 1) deep ground water flowpaths and 2) carbonate weathering, decrease with time since deglaciation as soil pans form, vegetation cover increases and soils become depleted in reactive minerals. We present here, detailed water and nutrient mass balances for three subarctic micro-catchments (<1 km2) located along a landscape maturity gradient in the Abisko area in northern Sweden. Stream- and soil water, precipitation and snowpacks were sampled frequently. Results include evidence of changing flowpath routing, DOC character and concentration of DIC and weathering products along this gradient. A conceptual model was suggested for long-term hydrological change in the Scandinavian mountainious area where the geomorphological setting causes an effective gradient in such related biogeochemical variables. The importance of a slow ground water flowpath increased with landscape maturity. It is suggested that this was mainly due to geomorphology; uniform soil conditions after deglaciation which are applicable for Alaskan catchments are replaced by erosion and transport of sediment from the top to the bottom of valleys. Hydrologic feedback on climatic change will depend upon the ultimate down-stream fate of organic and inorganic carbon but this study suggests that uptake of atmospheric CO2 in weathering reactions is an important negative feedback, especially in the flat bottom valleys with deep soils, dominated by a slow groundwater flowpath. Further, results provide evidence that a large part of the carbon input to high-altitude catchments is derived from microbial production within snowpacks. This input had a magnitude similar to overall loss of organic carbon, suggesting that snow melt carbon input significantly contributes to microbial and weathering processes within the soil of these systems.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available