Vegetal Undercurrents-Obscured Riverine Dynamics of Plant Debris.

Much attention has been focused on fine-grained sediments carried as suspended load in rivers due to their potential to transport, disperse, and preserve organic carbon (OC), while the transfer and fate of OC associated with coarser-grained sediments in fluvial systems have been less extensively studied. Here, sedimentological, geochemical, and biomolecular characteristics of sediments from river depth profiles reveal distinct hydrodynamic behavior for different pools of OC within the Mackenzie River system. Higher radiocarbon (C) contents, low N/OC ratios, and elevated plant-derived biomarker loadings suggest a systematic transport of submerged vascular plant debris above the active riverbed in large channels both upstream of and within the delta.

Climate control on terrestrial biospheric carbon turnover.

Terrestrial vegetation and soils hold three times more carbon than the atmosphere. Much debate concerns how anthropogenic activity will perturb these surface reservoirs, potentially exacerbating ongoing changes to the climate system. Uncertainties specifically persist in extrapolating point-source observations to ecosystem-scale budgets and fluxes, which require consideration of vertical and lateral processes on multiple temporal and spatial scales.

An Abrupt Aging of Dissolved Organic Carbon in Large Arctic Rivers.

Permafrost thaw in Arctic watersheds threatens to mobilize hitherto sequestered carbon. We examine the radiocarbon activity (FC) of dissolved organic carbon (DOC) in the northern Mackenzie River basin. From 2003-2017, DOC-FC signatures (1.