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Ocean floor metals coveted by mining companies can electrically produce “dark oxygen”, according to new research that will stoke debate over the impact of seabed commercialisation.
Scientists found the gas while exploring more than 4,000 metres deep in the Pacific Ocean, in a region rich in polymetallic nodules containing elements used to produce electric car batteries and other green energy technologies.
Plans by governments and companies to mine the world’s seabed for valuable industrial metals have triggered opposition from environmental groups that argue it could harm little understood marine ecosystems.
The research findings come as government officials gather in Jamaica to discuss the regulatory framework for deep sea mining at meetings organised by the International Seabed Authority, a UN-backed regulator.
The discovery of the deep sea oxygen would need to be factored into assessments of the impact of proposed mining, said Andrew Sweetman, leader of the latest research published on Monday in Nature Geoscience.
“Through this discovery, we have generated many unanswered questions -and I think we have a lot to think about in terms of how we mine these nodules, which are effectively batteries in a rock,” said Sweetman, who heads the seafloor ecology and biogeochemistry research group at the Scottish Association for Marine Science.
Sweetman’s team made the discovery while surveying the Clarion-Clipperton zone in the central Pacific, to examine the possible impact of mining there.
Polymetallic nodules in the area contain high quantities of nickel, manganese, cobalt and copper — metals used in green technologies from power lines to wind turbines.
The researchers were surprised to find that in almost all of their experiments oxygen levels rose over a couple of days.
After performing laboratory analysis and simulations, they suggested that electrical charge associated with the nodules split water into its constituent elements of hydrogen and oxygen.
The findings potentially add an extra dimension to understanding sources of undersea oxygen.
The world’s oceans are estimated to provide about half the production of the gas on earth, through organisms that — as on land — use light to turn carbon dioxide into oxygen through the process of photosynthesis.
The discovery of a possible source of oxygen in a region with no sunlight raises intriguing new questions about how life in the oceans began.
The authors were not able to estimate the overall size of the dark oxygen production effect and called for more work to do so.
Advocates of deep-sea mining argue the environmental harm caused by lifting nodules off the seabed would pale in comparison to the destruction unleashed by Indonesia’s boom to mine nickel on land.
Environmental groups retort that exploiting the deep sea for minerals comes with too many unknown impacts, with the latest scientific findings highlighting possible unintended consequences.
