Metal ecotoxicology: An essential component in ...

Underwater minerals, including manganese nodules, cobalt crusts and seafloor massive sulfides, are precipitated in abyssal plains, seamounts and hydrothermal vents worldwide, respectively (Figure 1A). The rising metal demand and prices, and the need to prevent mineral market monopolization in recent decades led the underwater mining interests increase again.1 Most of the proposed mining projects are located in the Clarion Clipperton Zone in Pacific Ocean (detailed list of proposed exploration sites: https://www.isa.org.jm/exploration-contracts/exploration-areas), predicted to yield 21 billion of dry metrics of nodules. One major controversy root in deep-sea mining (DSM) is the trade-off between environmental and economical values. Economic value of DSM is relatively easy to quantify by predicting the mining revenue, while assessing the environmental cost is more challenging. Highly invasive practice of DSM would ruin the unique and fragile habitats associated with these minerals, damaging ecosystem integrity and resulting net loss in biodiversity. Whether the environmental values at risk would be less or even worth the exchange for the economic benefits from non-renewable deep-sea minerals exploitation is debatable. Therefore, it must be first understood the authentic consequences of DSM on the environment before permitting exploitation projects.