High-arctic Weathering, Sulfide Mineral Oxidation and the Zackenberg River

• Main Authors: Stevenson, Emily, Murphy, Mel, Riis, Tenna, Tipper, Ed, Turchun, Sasha
• Format: Conference Object
• Language: English
• Published: 2018
• Subjects: Arctic; Greenland; permafrost; Zackenberg
• Online Access: https://pure.au.dk/portal/da/publications/higharctic-weathering-sulfide-mineral-oxidation-and-the-zackenberg-river(cf86d55d-8087-4164-b814-6a6a8451ae7c).html; https://pure.au.dk/ws/files/135406588/polar2018_abstractproceedings.pdf

The impact of weathering on atmospheric CO2 depends upon the balance between (1) alkalinity generation by carbonate and silicate mineral dissolution, and (2) sulfuric acid generation by the oxidation of sulfide minerals. In regions of high physical erosion, (e.g., mountainous and glaciated terrains), increased exposure and oxidation of sulfide minerals, such as pyrite, may change the balance of (1) to (2), leading such regions to become short term sources of CO2[1]. To test the influence of glacial erosion and permafrost freeze-thaw cycles in high-Arctic environments, we sampled from the Zackenberg River (NE Greenland), and surrounding tributaries, which individually integrate different lithologies, and are fed by either glacial rivers, seasonal snowmelt or seasonal permafrost thaw. Major cation and anion data revealed a major tributary, Aucellaelven, has an extremely high concentration of sulfate (SO42-), the highest in the region (>2mmol L-1). Here we present coupled sulfur and oxygen isotope data (δ34SSO4 and δ18OSO4) measured in SO42- to constrain the source of sulfur to the river system. Determining if the source of SO42- is from either evaporate mineral (sulfate containing) dissolution, or oxidative sulfide weathering, is vital to determining the importance of sulfuric acid in silicate weathering reactions in terrestrial Arctic environments, and the impact on inorganic carbon cycling in the region. [1]Torres et al. (2016) EPSL 450 381-391