DOC biodegradation behavior along permafrost affected hydrological continuum

Abstract

In Arctic regions, water bodies are hot spots of dissolved organic carbon (DOC) biodegradation, and their well-known large heterogeneity in the permafrost affected area could lead to a misrepresentation of their importance in the carbon (C) cycle. In this study, the biodegradation potential of various water bodies from two hydrological continuums has been assessed via 15 days aerobic incubation of waters. Results show that biodegradability of waters increases along the continuum while the removal rate of DOC decreases as the consequence of a preferential biodegradation of low molecular weight organic acids (LMWOA). This preferential uptake leads to a relative accumulation of aromatic compounds in the end-members of the continuum. This suggests a shift in the dominantly used pools of DOC along the continuum: a rapidly consumed DOC pool at the beginning of the continuum and a more slowly consumed one at the end of the continuum.