Metal release from manganese nodules in anoxic seawater and implications for deep-sea mining dewatering operations
The potential mining of deep-sea polymetallic nodules has been gaining increasing attention due to their enrichment in metals essential for a low-carbon future. To date, there have been few scientific studies concerning the geochemical consequences of dewatered mining waste discharge into the pelagic water column, which can inform best practices in future mining operations. Here, we report the results of laboratory incubation experiments that simulate mining discharge into anoxic waters such as those that overlie potential mining sites in the North Pacific Ocean. We find that manganese nodules are reductively dissolved, with an apparent activation energy of 42.8 kJ mol–1, leading to the release of associated metals in the order manganese > nickel > copper > cobalt > cadmium > lead. The composition of trace metals released during the incubation allows us to estimate a likely trace metal budget from the simulated dewatering waste plume. These estimates suggest that released cobalt and copper are the most enriched trace metals within the plume, up to ∼15 times more elevated than the background seawater. High copper concentrations can be toxic to marine organisms. Future work on metal toxicity to mesopelagic communities could help us better understand the ecological effects of these fluxes of trace metals.
Citation Information
Publication Year | 2024 |
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Title | Metal release from manganese nodules in anoxic seawater and implications for deep-sea mining dewatering operations |
DOI | 10.1021/acsestwater.4c00166 |
Authors | Yang Xiang, Janelle M. Steffen, Phoebe J. Lam, Amy Gartman, Kira Mizell, Jessica N. Fitzsimmons |
Publication Type | Article |
Publication Subtype | Journal Article |
Series Title | ACS ES&T Water |
Index ID | 70255718 |
Record Source | USGS Publications Warehouse |
USGS Organization | Pacific Coastal and Marine Science Center |