Towards an assessment of riverine dissolved organic carbon in surface waters of the western Arctic Ocean based on remote sensing and biogeochemical modeling

Abstract

Abstract. Future climate warming of the Arctic could potentially enhance the load of terrigenous dissolved organic carbon (tDOC) of Arctic rivers due to increased carbon mobilization within watersheds. A greater flux of tDOC might impact the biogeochemical processes of the coastal Arctic Ocean (AO) and ultimately its capacity to absorb atmospheric CO 2 . In this study, we show that sea-surface tDOC concentrations simulated by a physical-biogeochemical coupled model in the Canadian Beaufort Sea for 2003-2011 compare favorably with estimates retrieved by satellite imagery. Our results suggest that, over spring-summer, tDOC of riverine origin contributes to 35 % of primary production and that an equivalent of ∼ 10 % of tDOC is exported westwards with the potential of fueling the biological production of the eastern Alaskan nearshore waters. The combination of model and satellite data provides promising results to extend this work to the entire AO so as to quantify, in conjunction with in situ data, the expected changes in tDOC fluxes and their potential impact on the AO biogeochemistry at basin scale.

Exploring the Potential Role of Terrestrially Derived Humic Substances in the Marine Biogeochemistry of Iron

“…Biological processing of terrestrial humics will also need to be better represented. Recent evidence indicates that the first step may be a stimulation of bacterial metabolism in coastal waters (Vähätalo et al, 2011;Le Fouest et al, 2018), resulting in the transfer of iron into the biogenic phase and disrupting the coupling between terrestrial humics and iron. As such, biological processes may complicate efforts to model the fate of humic substances beyond coastal influences.…”

Understanding Regional and Seasonal Variability Is Key to Gaining a Pan-Arctic Perspective on Arctic Ocean Freshening

“…Organic carbon inputs from permafrost thaw (coastal erosion, river inputs) and glacier and ice sheet melt have been the topic of much attention recently, due to the potential for these vast, labile carbon stores to be exported to the coastal ocean (Hood et al, 2015;McClelland et al, 2016;Le Fouest et al, 2018;Wadham et al, 2019). Carbon in river runoff, eroded permafrost sediments, and glaciers has been found to be highly labile to microbial communities ( Table 2; Vonk et al, 2013;Paulsen et al, 2017;Sipler et al, 2017), causing both the quantity and quality of these inputs to influence ecosystem carbon cycling, and potentially converting large areas of coastal ocean into sources, rather than sinks, of CO 2 (discussed further below; Terhaar et al, 2019).…”

Comparisons of dissolved organic matter and its optical characteristics in small low and high Arctic catchments

“…Snowmelt and nival runoff start in early to mid-June with base flow establishing around early to mid-July. Refreezing of the active layer starts late August or early September (Lamoureux and Lafrenière, 2017;Lewis et al, 2012). Samples were taken downstream in Boundary River (152.5 km 2 ), its sub-catchment Robin Creek (14.8 km 2 ), and the neighbouring watersheds West River (8.6 km 2 ) and East River (12.0 km 2 ) (all unofficial names).…”