Photooxidation of arsenic in pristine and mine-impacted Canadian subarctic freshwater systems

The redox transformations of arsenic (As) in lakes are thought to be mainly controlled by algal/microbial processes. We tested if photochemical oxidation could also a significant process northern freshwater systems. exposed filtered natural water samples from four mine-impacted (Northwest Territories, Canada) and three unimpacted ponds (Nunavik, simulated solar radiation, followed As(III) oxidation. During short-term incubation experiments (less than 8 h), all amended with displayed rapid photooxidation (ca. 0.06-0.27 h−1) whereas no was observed the dark. This UV influenced short-lived oxidants partly driven concentrations organic matter. Natural As complexes unamended were more rapidly photooxidized amendments. Addition goethite or simulation snowmelt did not alter rates significantly. Overall, these results imply that should considered as potentially mechanism controlling inorganic speciation aquatic is particularly true for systems affected mining activities changes inputs matter related climate change.