Abstract:

Reactive sulfur compounds remain a global mining environmental challenge because of the on-going inability to accurately predict onset, and to effectively reverse impacts, such as acidity, toxicity, and contamination, once initiated. These inefficiencies, in part, reflect the lack of mechanistic understanding of microbially catalyzed sulfur processes that could improve prediction, management and mitigation of sulfur compound associated impacts. Despite now decades of profound discoveries that have led to transformational innovation from the application of molecular biological technologies (meta-‘omics), in many sectors (e.g., health care, agriculture, aquaculture, environmental conservation), mining has yet to fully embrace the opportunities to decrease risks through meta-‘omics integrated investigation that can more comprehensively inform understanding and improve environmental performance. Here, proof-of-principle results from a 5 year meta-‘omics integrated biogeochemical investigation of microbial sulfur cycling in four base metal tailings impoundments across Canada, established the first understanding of a distinct mining wastewater sulfur oxidizing bacteria (SOB) microbiome. Results identified a distinct group of SOB occurring across all mine tailings impoundments that play key roles in sulfur associated outcomes, signaling the broader relevance of these findings. These tailings impoundment SOB are largely novel, differing from those identified to occur in other, more well studied, sulfur reactive, anthropogenic and natural contexts, (e.g. ARD, sulfur springs, deep sea hydrothermal vents), revealing real opportunities to mine these endemic, adapted SOB for nature based wastewater solutions to better predict, monitor, manage and prevent sulfur associated environmental impacts. Results further revealed novel and important links between tailings wastewater geochemical characteristics and their influence on SOB identities and sulfur cycling, and water quality outcomes, that are not captured by current geochemical (abiotic) models. These results underscore the importance of such biologically integrated investigation to more comprehensively constrain important biogeochemical processes, identify relevant controls and predict outcomes. This emerging biologically informed framework of sulfur reactivity lays the groundwork for development of more effective system based, sulfur monitoring tools and adaptive management approaches, as well as more sustainable treatment strategies. They also highlight the broader opportunities to improve mining water stewardship through application of molecular microbiological technologies to a host of persistent environmental challenges still faced by the industry.

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Stephanie Marshall