Chemical denudation and the role of sulfide oxidation at Werenskioldbreen, Svalbard

Abstract

This study aims to determine the rate of chemical denudation and the relationships between dominant geochemical reactions operating in the proglacial and subglacial environments of the polythermal glacier Werenskioldbreen (SW Svalbard) during an entire ablation season. Water sampling for major ion chemistry was performed at a proglacial hydrometric station and from subglacial outflows from May to September 2011. These data were combined with measurements of discharge and supraglacial ablation rates. The slopes and intercepts in bestfit regressions of [*Ca 2+ +*Mg 2+ vs. *SO 4 2-] and [HCO 3 vs. *SO 4 2-] in meltwater from icemarginal subglacial channels were close to the stoichiometric parameters of sulfide oxidation and simple hydrolysis coupled to carbonate dissolution (*concentrations corrected for input of sea-salt). This shows that these relationships predominates the meltwater chemistry. Our findings also show that sulfide oxidation is a better indicator of the configuration of subglacial drainage systems than, for instance, Na + and K +. In the proglacial area and in sub-artesian outflows, the ion associations represent sulfide oxidation but other processes such as ion exchange and dissolution of Ca and Mg efflorescent salts may also contribute to the solute variations. These processes may cause enhanced fluxes of Ca 2+ and HCO 3 from glacierised basins during the early ablation and peak flow seasons as the proglacial salts re-dissolve. The overall chemical denudation rate in the basin for 2011 (ranging from 1601 and 1762 meq m-2 yr-1 (121.9 and 132.2 t km-2 yr-1)) was very high when compared to other Svalbard valley glaciers suggesting that the high rate of chemical denudation was mostly caused by the high rates of discharge and ablation. Chemical weathering intensities (876 and 964 meq m-3 yr-1) exceeded previously reported intensities in Svalbard.

Diversity and distribution of Tardigrada in Arctic cryoconite holes

“…Water samples were collected in 0.12 dm -3 bottles and stored at 3°C in (Stachnik et al, 2016). The quality of analyses were determine by charge balance error for each sample: 1.4% (sample 29); 22% (sample 30), and 3.3% (sample 31).…”

Observed sediment and solute transport from the Kangerlussuaq sector of the Greenland Ice Sheet (2006–2016)

“…Here, we use a compiled set of solute data, consisting of sixty-four previously published analyses from 2007 to 2009 (described in detail by Yde et al 2014), together with thirteen analyses from samples from 2013. We only include samples collected during the peak flow period in July and August because inclusion of samples collected during the early and late melt season may cause an overestimation of annual transports (Krawczyk, Lefauconnier, and Pettersson 2003;Stachnik et al 2016;Yde et al 2008). We present concentrations and transport of major ions (Na We use the discharge-weighted method, where measured ion concentrations are multiplied by the discharge at the time of sampling.…”

Glaciers as an Important Element of the World Glacier Monitoring Implemented in Svalbard

“…The chemical composition of glacial meltwaters in Svalbard has been subject to increased interest in recent years [34][35][36][37]. Waters originating from glaciers affect the quantity and quality of water delivered to the environment in glaciated catchments, which also plays an important role in ice mass dynamics [13].…”

“…pH [37,38,65] Orion SA 250 portable meter with a Ross combination electrode [34] Jenco pH-meter [35] Orion (Thermo Scientific), WPA (Cambridge, UK) or VWR pH meter [36] EC CC-317 conductivity meter [35] Anions (Cl Dionex Ion Chromatography [65] Dionex DX100 [40,36] IC, colorimetric method [38] Dionex 4000i [34] Metrohm Compact IC 761 [35,37] Dionex DX-120 [12] Dionex ICS-90 [76,36] HCO 3 À IC Dionex 4000i [75] Dionex DX-120 [12] Titration (10 À3 molc/L H 2 SO 4 ) [65] Colorimetric titration [38] Titration (1 mmol HCl) [34] Titration (10 mmol HCl) [36] Titration (0.02 M HCl) [35] Titration (Metrohm 702 SM Titrino) [37] N-NO 2 À IC Dionex DX-120 [12] N-NO 3 À Dionex Ion Chromatography [65] Dionex DX-120 [12] N-NH 4 þ Dionex DX-120 [12] FIA [65] Cations (Na…”