Abstract:

A large fraction of all lakes on the earth is represented by the high latitude lakes, contributing up to 18.8 Tg methane emission (twice the emission from the oceans) into the atmosphere per year that has critical implications for global climate. Anaerobic oxidation of methane (AOM) is a major biogeochemical process that plays a pivotal role in mitigating methane emissions to the atmosphere in the absence of oxygen in various ecosystems. The high latitudes (boreal/sub-boreal zones) are where an estimated 80% of the mining in Canada occurs. The impacts of mine drainage generated from mining of massive sulfide ore bodies (mine effluent) on the quality and geochemistry of waters and sediments characterized by high concentrations of Fe²⁺, SO₄^2-, heavy metals and other constituents have been well documented for lakes and pit lakes. Despite these lake sediments being one of the largest global sinks for methane (as a very potent greenhouse gas), anaerobic oxidation of methane and the impacts of mining activities on this important biogeochemical process (particularly AOM linked to iron) is still very poorly understood both in terms of geochemistry and characterization of the organisms and consortia involved. Notably, Canadian lakes are critically understudied, with CH₄ emissions measured from only four lakes to date. Mesocosm experiments were set up with sediments collected from mining impacted lakes and pristine lakes (as controls) located in northern Ontario and BC. We are using a holistic system biology approach combining tools in genomics, geochemistry, and environmental microbiology to assess microbial communities and metabolic traits involved in AOM within the context of mining-impacted environments and the consequences for methane emission in high-latitude regions. In this poster, we will outline our experimental design and approach, and discuss the implications of such knowledge for improvement of global biogeochemical and climate projection models.

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Dr. Michael Preston