Scientists Launch Deep-Sea Expedition to Investigate ‘Dark Oxygen’

A team of scientists has announced plans for a significant deep-sea expedition to investigate an intriguing phenomenon known as “dark oxygen.” Led by British marine ecologist Andrew Sweetman, the team aims to explore metallic rocks at the ocean’s depths, which their previous research suggested could be generating this previously unknown form of oxygen. If verified, this discovery could challenge long-standing beliefs about the origins of oxygen in Earth’s atmosphere and its implications for life on our planet.

To facilitate this research, the team has developed two new deep-sea landers capable of descending to depths of up to 11 kilometres (approximately seven miles). These advanced landers, designed to withstand pressures equivalent to 1,200 times that found on the Earth’s surface, will be deployed from a research vessel in the Clarion-Clipperton Zone, a region situated between Hawaii and Mexico. The expedition is scheduled for May 2024, according to the team.

The landers will be equipped with specialized sensors intended to measure seafloor respiration, thereby assessing how the metallic nodules, which resemble potato-sized rocks, might be producing oxygen through a process known as electrolysis. Sweetman emphasized that these nodules could potentially split seawater into hydrogen and oxygen, providing a new perspective on underwater chemistry.

Despite the excitement surrounding the upcoming expedition, skepticism exists within the scientific community and the emerging deep-sea mining industry. Some researchers have raised concerns about the origins of the detected oxygen, suggesting that it may simply be air bubbles trapped within the measuring instruments used in Sweetman‘s earlier studies. In response, Sweetman defended the reliability of his instruments, stating, “We’ve used these instruments over the last 20 years, and every time we’ve deployed them, we’ve never had bubbles.”

The deep-sea mining industry is particularly interested in the extraction of valuable metals found within these nodules, which are crucial for technologies such as electric car batteries. The Metals Company, a Canadian deep-sea mining firm, partly funded Sweetman’s 2024 study but has since criticized his findings. Sweetman noted that if commercial mining proceeds, it could have widespread environmental impacts, as these nodules serve as habitats for diverse marine life. He clarified that his intention is not to derail mining efforts but rather to gather information that could help mitigate potential environmental damage.

The upcoming research will also involve collaboration with other scientists. Matthias Haeckel, a biogeochemist at Germany’s GEOMAR Helmholtz Centre for Ocean Research, expressed his own findings did not support the idea of oxygen production from the nodules. Haeckel stated he would join Sweetman’s cruise later this year to compare research methodologies.

The results of this expedition may take several months to confirm. Sweetman mentioned that the team expects to determine the presence of dark oxygen within 24 to 48 hours after retrieving the landers. However, the broader scientific community and the public will likely have to wait until the ship returns in June 2024 for a complete report, alongside further experiments conducted on land.

As the debate continues over the environmental implications of deep-sea mining, this expedition could provide critical insights into both the biological and geological processes occurring in the ocean’s depths. The findings may not only reshape our understanding of oceanic ecosystems but could also influence future regulations in an industry poised for significant expansion.