Geology topics
Publications and source records attributed to Suzanne Tank.
Research has traditionally focused on atmospheric release of carbon from thawing permafrost, yet overlooked waterborne release pathways likely contribute significantly, especially in a warming Arctic. To address this knowledge gap and better constrain the fate of carbon in the North, we recommend inter-disciplinary efforts bridging physical, chemical and computational research.
While much of the dissolved organic carbon (DOC) within rivers is destined for mineralization to CO 2 , a substantial fraction of riverine bicarbonate (HCO 3 - ) flux represents a CO 2 sink, as a result of weathering processes that sequester CO 2 as HCO 3 - . We explored landscape-level controls on DOC and HCO 3 - 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 HCO 3 - flux were near-universal: runoff and an increased carbonate rock contribution to weathering (assessed as riverwater Ca:Na) increased HCO 3 - yields, while increasing permafrost extent was associated with decreases in HCO 3 - . 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 SO 4 yields to calculate the potential range of CO 2 sequestered via weathering across these boreal subcatchments, and show that decreasing permafrost extent is associated with increases in weathering-mediated CO 2 fixation across broad spatial scales, an effect that could counterbalance some of the organic C mineralization that is predicted with declining permafrost.