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Origin and temporal variability of unusually low δ 13 C‐DOC values in two High Arctic catchments
Author(s) -
Hindshaw R. S.,
Lang S. Q.,
Bernasconi S. M.,
Heaton T. H. E.,
Lindsay M. R.,
Boyd E. S.
Publication year - 2016
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2015jg003303
Subject(s) - permafrost , dissolved organic carbon , arctic , environmental chemistry , organic matter , environmental science , cycling , δ13c , carbon cycle , streams , methane , isotopes of carbon , carbon fibers , thermokarst , total organic carbon , physical geography , oceanography , stable isotope ratio , ecology , chemistry , geology , ecosystem , geography , biology , materials science , computer network , archaeology , composite number , computer science , composite material , quantum mechanics , physics
The stable carbon isotopic composition of dissolved organic matter ( δ 13 C‐DOC) reveals information about its source and extent of biological processing. Here we report the lowest δ 13 C‐DOC values (−43.8‰) measured to date in surface waters. The streams were located in the High Arctic, a region currently experiencing rapid changes in climate and carbon cycling. Based on the widespread occurrence of methane cycling in permafrost regions and the detection of the pmoA gene, a proxy for aerobic methanotrophs, we conclude that the low δ 13 C‐DOC values are due to organic matter partially derived from methanotrophs consuming biologically produced, 13 C‐depleted methane. These findings demonstrate the significant impact that biological activity has on the stream water chemistry exported from permafrost and glaciated environments in the Arctic. Given that the catchments studied here are representative of larger areas of the Arctic, occurrences of low δ 13 C‐DOC values may be more widespread than previously recognized, with implications for understanding C cycling in these environments.