Soil and Water Chemistry Characteristics of Thermo-Erosional Features in the Western Noatak River Basin, Alaska, USA

摘要

In 2007, 24 thermal-erosion and permafrost degradation features (hereafter "thermokarst") were characterized in northwest Alaska, USA. Geomorphic assessments showed that active-layer detachments and thaw slumps had characteristic morphologies with permafrost thaw depths significantly deeper within these features (106 cm) than surrounding hillslopes and water tracks (86 cm). Characterization of soils and water associated with these features showed that reference transects above each feature were significantly different from feature transects (headwall, active surface, run-out). Water collected within the features showed significantly higher concentrations of nutrients (ammonium, nitrite), total dissolved nitrogen, dissolved organic and inorganic carbon, and anions (chloride and bromide) compared to the reference transect. Water samples from reference transects had higher soil electrical conductivity, calcium, and ratio of DOC:DON. Though thermokarst failures are a relatively rare spatial and temporal feature of the arctic landscape, they play an important role in the biogeochemical processing of terrestrial and aquatic resources of the Arctic.