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Landscape-level controls on dissolved carbon flux from diverse catchments of the circumboreal

Global Biogeochemical Cycles

By:
, , , , , , and
DOI: 10.1029/2012GB004299

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Abstract

While much of the dissolved organic carbon (DOC) within rivers is destined for mineralization to CO2, a substantial fraction of riverine bicarbonate (HCO3-) flux represents a CO2 sink, as a result of weathering processes that sequester CO2 as HCO3-. We explored landscape-level controls on DOC and HCO3- flux in subcatchments of the boreal, with a specific focus on the effect of permafrost on riverine dissolved C flux. To do this, we undertook a multivariate analysis that partitioned the variance attributable to known, key regulators of dissolved C flux (runoff, lithology, and vegetation) prior to examining the effect of permafrost, using riverine biogeochemistry data from a suite of subcatchments drawn from the Mackenzie, Yukon, East, and West Siberian regions of the circumboreal. Across the diverse catchments that we study, controls on HCO3- flux were near-universal: runoff and an increased carbonate rock contribution to weathering (assessed as riverwater Ca:Na) increased HCO3- yields, while increasing permafrost extent was associated with decreases in HCO3-. In contrast, permafrost had contrasting and region-specific effects on DOC yield, even after the variation caused by other key drivers of its flux had been accounted for. We used ionic ratios and SO4 yields to calculate the potential range of CO2 sequestered via weathering across these boreal subcatchments, and show that decreasing permafrost extent is associated with increases in weathering-mediated CO2 fixation across broad spatial scales, an effect that could counterbalance some of the organic C mineralization that is predicted with declining permafrost.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Landscape-level controls on dissolved carbon flux from diverse catchments of the circumboreal
Series title:
Global Biogeochemical Cycles
DOI:
10.1029/2012GB004299
Volume
26
Year Published:
2012
Language:
English
Publisher:
American Geophysical Union
Publisher location:
Washington, D.C.
Contributing office(s):
Branch of Regional Research-Central Region
Description:
15 p.; GB0E02
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Global Biogeochemical Cycles
Number of Pages:
15
Other Geospatial:
Circumboreal