Abstract:

Microbes Across the Mine-Life Cycle: A New Paradigm Understanding ML/ARD Drivers

Kelly Whaley-Martin (ERM), Nadia Mykytczuk (Laurentian University), Roberta Pedlar-Hobbs (ERM)

Across the mine life-cycle, delineating and managing metal leaching/acid rock drainage (ML/ARD) risk remains a critical and often costly aspect of water management. The industry continues to devote relatively significant resources to predict (kinetic testing during baseline programs and water quality modelling) and monitor (surface water, seepage and groundwater) water quality through operations and closure. While advanced scientific knowledge is available that demonstrates environmental microbial communities drive ML/ARD, the industry frameworks remain solely focused on delineating abiotic chemical symptoms. This work provides case-studies led by ERM geochemists applied across the mine life cycle where inclusions of microbial delineations in waste rock and mining water provided concrete evidence that investigating ML/ARD through a biogeochemical lens is the next paradigm in water quality management.

In the first case study, a baseline geochemical program for a Cu/Ni mine applied microbial genomics in parallel with traditional methodologies in a humidity cell and field leach barrel testing program. This resulted in the identification of proactive biomarkers (in-situ sulfide mineral oxidizing bacteria) capable of driving the early onset of ARD in waste rock. The two other case-studies incorporated microbial genomic characterization into a tailings impoundment water-cap assessment at an operational Ni/Cu mine (Whaley-Martin et al., Nature Communications, 2023) and in a previous receiving environment at a closed Cu mine site on Vancouver Island, British Columbia. In both cases, in situ microbial genomics provided critical insights into water quality drivers at these mine sites that wouldn’t have occurred solely through an abiotic traditional lens.

Each case provides a practical and proven roadmap the mining industry can leverage to apply microbial genomics to significantly improve the understanding of the drivers of ML/ARD at proposed, operational and closed mines.

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Joanna Majarreis