Source: Water Resources Research
Waste rock dumps are the main sources of acid and metalliferous drainage (AMD) at mine sites globally. AMD has been identified by the United Nations as the biggest environmental problem second to climate change, yet access to large hydrogeochemical monitoring datasets from waste rock dumps are scarce.
Bao et al.  present a rich, rare, and complete hydrogeochemical dataset from a sulfide-bearing waste pile within a challenging field site: the discontinuous permafrost region of Northern Canada. They find that hydrological processes—including precipitation, evaporation, and infiltration—and hydrological and thermal responses to freeze-thaw and dry-wet cycles, control water quantity and quality from mining waste-rock materials.
Together with detailed physical process characterization, this study demonstrates that at this site, where net infiltration into waste rock occurs largely from rainfall, changes in water content occurred in the preferential flow pathways mainly in response to freeze-thaw and dry-wet cycles, whereas changes in water content could be neglected in the matrix-dominated zones of the waste-rock pile.
The findings emphasize the importance of mitigating infiltration of water and oxygen for remediation and reclamation of sulfide-bearing waste-rock pile for long-term ecosystem preservation and could be used by others to calibrate numerical models and help design field monitoring.
Citation: Bao, Z., Bain, J., Holland, S. P., Wilson, D., Ptacek, C. J., & Blowes, D. W. . Hydrogeochemical response of a variably saturated sulfide-bearing mine waste-rock pile to precipitation: A field-scale study in the discontinuous permafrost region of Northern Canada. Water Resources Research, 58, e2021WR031082. https://doi.org/10.1029/2021WR031082
—Kamini Singha, Editor, Water Resources Research