Evolving drainage networks and nutrient fluxes in continuous permafrost zones of interior and arctic Alaska
Abstract
It is generally accepted that permafrost thaw will release carbon and nutrients into high-latitude environments. However, utilization of these additions is highly dependent on hydrologic transport within ecosystems. Here we compare two headwater catchments in the interior Alaska and two sites further north on the Arctic Coastal Plain. All sites are underlain by continuous permafrost and summer warming leads to seasonal deepening of the active layer up to 0.3 to 1 m in early August. This annual thaw cycle promotes water and solute infiltration and storage, and often allows rapid movement of water and solutes near the organic/mineral and freeze/thaw soil boundaries. We present data from laboratory incubations, runoff and interflow sampling, and natural and manipulative stream nutrient additions. Our results indicate 1) the ability of runoff to access and thaw solute-rich water at the top of the permafrost, 2) the high concentrations of carbon, nitrogen, and phosphorous that can be delivered to aquatic ecosystems, and 3) the potential for rapid nutrient assimilation and cycling in ponds and low-order streams. We also provide evidence that rapid transport often limits actual cycling/assimilation rates. Understanding these coupled hydrological and biogeochemical processes is increasingly a focus of catchment and polar hydrology and will aid in predicting the effects of decadal-scale permafrost thaw and subsurface flowpath and drainage network evolution on nutrient fluxes and cycling.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFMGC12A..07K
- Keywords:
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- 0470 BIOGEOSCIENCES / Nutrients and nutrient cycling;
- 0706 CRYOSPHERE / Active layer;
- 1804 HYDROLOGY / Catchment;
- 1830 HYDROLOGY / Groundwater/surface water interaction