Recent research published in Nature Geoscience reveals that mining rare metals from the deep sea could produce a form of oxygen dubbed “dark oxygen” and potentially disrupt marine ecosystems. This phenomenon occurs when polymetallic nodules, which form over millions of years on the ocean floor, react with salt water during mining operations.
Key findings:
- Dark oxygen production:
- The study identifies “dark oxygen” as oxygen generated without sunlight, similar to how conventional batteries release energy. Polymetallic nodules, containing metals like cobalt, lithium and copper, act like batteries when disturbed, producing more oxygen in the process.
- Impact on marine ecosystems:
- The production of dark oxygen could impact deep-sea ecosystems by altering oxygen levels in the ocean’s abyssal plains, where these nodules are found. This area is covered in sediment and hosts various marine organisms that rely on existing oxygen levels.
- Experimental findings:
- Researchers deployed chambers on the seafloor at depths of about 2.6 miles in the Clarion–Clipperton Zone. They observed an increase in oxygen concentration, suggesting the nodules’ electrical properties could be responsible. This led to the hypothesis of a “geo-battery,” where nodules generate voltage similar to that of AA batteries.
- Broader implications:
- While it’s challenging to quantify the overall oxygen production from these nodules, mining could affect their capacity to support deep-sea life. Oceans produce about half of Earth’s oxygen, mainly through photosynthesis by marine organisms. Disrupting this process could have far-reaching consequences.
- Call for caution:
- Over 800 marine scientists have petitioned for a halt on deep-sea mining activities until further research is conducted. They argue that deep-sea ecosystems are already under stress from climate change, pollution, and bottom trawling.
This study underscores the need for a careful evaluation of the environmental impacts of deep-sea mining before proceeding with large-scale operations.
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