Karen E. Frey Robert G. Striegl Peter A. Raymond R. Max Holmes James W. McClelland Bruce J. Peterson Suzanne Tank 2012 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. application/pdf 10.1029/2012GB004299 en American Geophysical Union Landscape-level controls on dissolved carbon flux from diverse catchments of the circumboreal article