Abstract

Here, results from a case study examining the unexplored roles of endemic mine tailings impoundment microorganisms in the generation, alteration and stability of reactive sulfur compounds (i.e. “thiosalts”)  will demonstrate how genomics integrated investigation improves understanding and decreases risks.  Reactive sulfur compounds remain a global mining environmental challenge because of the on-going inability to accurately predict onset of acid rock drainage (ARD), and to effectively reverse impacts, such as acidity, toxicity, and contamination, once initiated. TThese inefficiencies highlight important knowledge gaps exist. In particular critical understanding of how microorganisms are implicated in processes controlling the types, concentrations and spatial-temporal occurrence of sulfur compounds in tailings impoundments is currently lacking. 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 biologically integrated understanding and improve environmental performance. Here, proof-of-principle results from this 5 year meta-‘omics integrated biogeochemical investigation of microbial sulfur cycling in four base metal tailings impoundments across Canada will be presented.  Results identified a common group of sulfur oxidizing bacteria (SOB) that occur across the four investigated mine tailings impoundments and receiving environments consistent with a distinct tailings impoundment SOB microbiome adapted to, and interactive with tailings impoundment waters.  This SOB microbiome plays key roles in tailings impoundment sulfur associated outcomes, signaling the broader relevance of these findings to mine operations processing sulfide hosted ores. 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 tailings impoundment adapted SOB for nature based mining focused wastewater solutions.  Results further revealed novel and important links between tailings wastewater environmental and geochemical characteristics, SOB identities and pathways of 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  better predict, monitor, manage and prevent sulfur associated environmental impacts. 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 mine water environmental performance through application of molecular microbiological technologies to a host of persistent environmental challenges where biological processes are likely involved, still faced by the industry.