Organic carbon fluxes of a glacier surface: A case study of Foxfonna, a small Arctic glacier

Abstract

Arctic glaciers are rapidly responding to global warming by releasing organic carbon (OC) to downstream ecosystems. The glacier surface is arguably the most biologically active and biodiverse glacial habitat and therefore the site of important OC transformation and storage, although rates and magnitudes are poorly constrained. In this paper, we present measurements of OC fluxes associated with atmospheric deposition, ice melt, biological growth, fluvial transport and storage (in superimposed ice and cryoconite debris) for a supraglacial catchment on Foxfonna glacier, Svalbard (Norway), across two consecutive years. We found that in general atmospheric OC input (averaging 0.63 ± 0.25 Mg a‐1 total organic carbon, i.e. TOC, and 0.40 ± 0.22 Mg a‐1 dissolved organic carbon, i.e. DOC) exceeded fluvial OC export (0.46 ± 0.04 Mg a‐1 TOC and 0.36 ± 0.03 Mg a‐1 DOC). Early in the summer, OC was mobilised in snowmelt but its release was delayed by temporary storage in superimposed ice on the glacier surface. This delayed the export of 28.5% of the TOC in runoff. Biological production in cryoconite deposits was a negligible potential source of OC to runoff, while englacial ice melt was far more important on account of the glacier's negative ice mass balance (–0.89 and –0.42 m a‐1 in 2011 and 2012, respectively). However, construction of a detailed OC budget using these fluxes shows an excess of inputs over outputs, resulting in a net retention of OC on the glacier surface at a rate that would require c. 3 years to account for the OC stored as cryoconite debris. © 2018 John Wiley & Sons, Ltd.

Spatiotemporal variability of elemental and organic carbon in Svalbard snow during 2007–2018

“…These circumstances could explain why the and were particularly high in the accumulation zones of Hansbreen and Werenskioldbreen in April 2016, and also why >65 % of the accumulated EC was found in the deepest part of the snowpack at these sites. It also suggests that a few large precipitation events could explain a large part of the interannual variability in and across Svalbard, as was previously observed for wet deposition of SO4 2-, NO3and OC on glaciers near Hornsund (Kühnel et al, 2013;Kozioł et al, 2019).…”

Terrestrial Inputs Drive Seasonality in Organic Matter and Nutrient Biogeochemistry in a High Arctic Fjord System (Isfjorden, Svalbard)

“…The permafrost active layer is deepest in August (Christiansen et al, 2005), a typically low discharge period (Hodson et al, 2016) when glacial-meltwater has higher residence time in the catchment. Seasonal changes in catchment hydrology have implications for the transport and bioavailability of carbon and nutrients in glacial meltwater on Svalbard (Nowak and Hodson, 2015;Koziol et al, 2019) and elsewhere in the Arctic (Neff et al, 2006;Holmes et al, 2008;Spencer et al, 2008). For example, carbon delivered during spring freshet in Alaskan rivers is more labile compared to aged, microbially reworked carbon delivered later in the summer (Holmes et al, 2008).…”

Extreme weather event results in the removal of invertebrates from cryoconite holes on an Arctic valley glacier (Longyearbreen, Svalbard)

“…Glaciers account for ~70% of stored freshwater are the main contributors to sea level rise and play an important role in the global carbon cycle (Hodson et al, ; Koziol, Moggridge, Cook, & Hodson, ; Stibal et al, ). Glaciers as part of the cryosphere cover ~10% of the terrestrial surface and constitute the coldest biome on our planet (Anesio & Laybourn‐Parry, ).…”