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Spatial variation in concentration and sources of organic carbon in the Lena River, Siberia
Author(s) -
Kutscher Liselott,
Mörth CarlMagnus,
Porcelli Don,
Hirst Catherine,
Maximov Trofim C.,
Petrov Roman E.,
Andersson Per S.
Publication year - 2017
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2017jg003858
Subject(s) - tributary , permafrost , total organic carbon , environmental science , dissolved organic carbon , drainage basin , arctic , hydrology (agriculture) , vegetation (pathology) , spatial variability , physical geography , oceanography , geology , ecology , geography , statistics , geotechnical engineering , mathematics , medicine , cartography , pathology , biology
Global warming in permafrost areas is expected to change fluxes of riverine organic carbon (OC) to the Arctic Ocean. Here OC concentrations, stable carbon isotope signatures (δ 13 C), and carbon‐nitrogen ratios (C/N) are presented from 22 sampling stations in the Lena River and 40 of its tributaries. Sampling was conducted during two expeditions: the first in July 2012 in the south and southeastern region and the second in June 2013 in the northern region of the Lena basin. The data showed significant spatial differences in concentrations and major sources of OC. Mean subcatchment slopes were correlated with OC concentrations, implying that mountainous areas in general had lower concentrations than lowland areas. δ 13 C and C/N data from tributaries originating in mountainous areas indicated that both dissolved and particulate OC (DOC and POC) were mainly derived from soil organic matter (SOM). In contrast, tributaries originating in lowland areas had larger contributions from fresh vegetation to DOC, while aquatically produced OC was the major source of POC. We suggest that these differences in dominant sources indicated differences in dominant flow pathways. Tributaries with larger influence of fresh vegetation probably had surficial flow pathways, while tributaries with more SOM influence had deeper water flow pathways. Thus, the future export of OC to the Arctic Ocean will likely be controlled by changes in spatial patterns in hydroclimatology and the depth of the active layers influencing the dominant water flow pathways in Arctic river basins.