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Mahesh

27/07/24 11:54 AM IST

Surprising ‘dark oxygen’ discovery could ensnarl deep-sea mining

In News
  • An unknown process is producing oxygen deep in the world’s oceans, where it is too dark for photosynthesis, scientists reported recently.
About the study
  • The oxygen discovery raises questions about how deep-sea mining to extract polymetallic nodules will affect marine ecosystems.
  • The scientists behind the study, from Germany, the U.K., and the U.S., were studying the Clarion-Clipperton Zone, a part of the ocean floor off Mexico’s west coast.
  • Covering an area larger than India, the Zone is considered to have the world’s highest concentration of polymetallic nodules, including 6 billion tonnes of manganese and more than 200 million tonnes each of copper and nickel.
  • When the scientists were conducting experiments at a depth of 4 km, they noticed the oxygen concentration in some places rapidly increased instead of decreasing.
  • They conducted follow-up studies in 2020 and 2021.
  • In each case, they released a device from the surface that would land on the ocean floor, where it would isolate a small volume of the floor along with some sea water and measure the oxygen levels.
  • This underwater region is called the abyssal zone. It receives too little sunlight for photosynthesis to be feasible.
  • Instead, life-forms here get oxygen from water carried in by a global circulation called the ‘Great Conveyor Belt’.
  • Still, the amount of oxygen is low and without any local production, the device should have measured the oxygen levels dropping as small animals consumed it.
  • But the scientists found the opposite: it increased, sometimes tripling in just two days.
Deep sea Mining
  • Given the quantity of metals polymetallic nodules on the ocean floor hold, deep-sea mining is expected to be a major marine resource extraction activity in the coming decades.
  • The International Seabed Authority has established 15-year contracts with at least 22 contractors — including the Government of India — to look for polymetallic nodules, polymetallic sulphides, and cobalt-rich ferromanganese crusts in the deep seabed.
  • China alone is expected to mine 17% of the Clarion-Clipperton Zone.
  • The new finding raises the possibility of such mining damaging ecosystems that require ‘dark oxygen’ to survive.
  • Experts have found deep-sea mining itself could be harmful to the marine environment, ‘dark oxygen’ or not.
Source- The Hindu

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