organic covers response to climate change. Potential impacts of climate change on biogeochemistry of mine wastes and efficiency of organic covers

Mine environments in boreal and sub-boreal zones are expected to experience extreme weather events, increases in temperature, and shifts in precipitation patterns. Climate change impacts on the geochemical stability of tailings contaminants and reclamation structures have been identified as important climate-related challenges to the Canadian mining sector. Adapting current reclamation strategies in addition to proactive adaptation planning for climate change will improve the long-term efficiency and viability of mine tailings remediation/restoration strategies under a changing climate. Accordingly, mesocosm experiments were conducted to investigate associations of climate-driven shifts in microbial communities and functions with changes in the geochemistry of organic covers and underlying tailings. Our results show that warming appears to significantly reduce C:N of the organic cover and promote infiltration of nitrogen into the deeper, unoxidized strata of underlying tailings. We have also observed an increase in the abundance of some nitrate reducers and sulfide oxidizers in microbial communities in underlying tailings that raises the concern that warming might trigger oxidation of sulfide minerals (linked to nitrate reduction) in the deeper unoxidized strata where the oxygen has been eliminated. These findings have implications for the development of climate resilient mine tailings remediation/restoration strategies.