Enhanced physical weathering in the Arctic through glacial retreat, permafrost thaw and collapse is exposing and mobilising vast amounts of finely-ground sediment to the agents of weathering. Elevated pyrite mineral oxidation caused by the exposure of sulfide minerals in sedimentary lithologies can generate sulfuric acid which can weather freshly exposed carbonate minerals and release Carbon dioxide (CO2) to the atmosphere. In this talk I will present a high resolution and long term geochemical data set from a high Arctic River (Zackenberg River, Northeast Greenland). Elemental and isotopic measurements allow river water chemistry to be partitioned between the different sources of acidity and mineral endmembers in order to quantify the net CO2 fluxes from the Zackenberg river catchment, and how these chemical weathering reactions have evolved daily, seasonally and annually over the past 20 years.
Net CO2 budget calculations show that every year the Zackenberg River Catchment has resulted in a net CO2 flux to the atmosphere, the opposite of what is predicted via traditional silicate weathering calculations and theory. The total balance of CO2 release varies from year to year, with some of the largest CO2 release fluxes associated with the high erosion rates, and large rainfall events. This scenario could represent a small but plausible modern-day positive climate feedback loop, which is unaccounted for in coupled CO2-climate models.