Scientists have discovered “dark oxygen” being produced in the deep ocean, apparently by lumps of metal on the seafloor.
About half the oxygen we breathe comes from the ocean. But, before this discovery, it was understood that it was made by marine plants photosynthesising – something that requires sunlight.
Here, at depths of 5km, where no sunlight can penetrate, the oxygen appears to be produced by naturally occurring metallic “nodules” which split seawater – H2O – into hydrogen and oxygen.
Several mining companies have plans to collect these nodules, which marine scientists fear could disrupt the newly discovered process – and damage any marine life that depends on the oxygen they make.
“I first saw this in 2013 – an enormous amount of oxygen being produced at the seafloor in complete darkness,” explains lead researcher Prof Andrew Sweetman from the Scottish Association for Marine Science. “I just ignored it, because I’d been taught – you only get oxygen through photosynthesis.
“Eventually, I realised that for years I’d been ignoring this potentially huge discovery,” he told BBC News.
He and his colleagues carried out their research in an area of the deep sea between Hawaii and Mexico – part of a vast swathe of seafloor that is covered with these metal nodules. The nodules form when dissolved metals in seawater collect on fragments of shell – or other debris. It’s a process that takes millions of years.
And because these nodules contain metals like lithium, cobalt and copper – all of which are needed to make batteries – many mining companies are developing technology to collect them and bring them to the surface.
But Prof Sweetman
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