An international team of scientists has discovered that metallic nodules on the Pacific Ocean’s seafloor produce oxygen in complete darkness, a groundbreaking finding published in Nature Geoscience. The revelation raises significant concerns about the environmental impact of deep-sea mining.
Led by Professor Andrew Sweetman of the UK’s Scottish Association for Marine Science, the study found that oxygen is generated approximately 4,000 meters (13,100 feet) below the ocean’s surface. This contradicts the long-held belief that only photosynthetic organisms could produce oxygen. “For aerobic life to begin on the planet, there had to be oxygen, and our understanding has been that Earth’s oxygen supply began with photosynthetic organisms,” Sweetman explained.
Unraveling the Mystery of Deep-Sea Oxygen Production
The scientists first noticed anomalies in oxygen levels during a 2013 fieldwork expedition in the Clarion–Clipperton Zone, a mineral-rich area between Hawaii and Mexico. This region, targeted for mining, revealed unexpected increases in oxygen levels in sequestered seawater. Initially dismissed as sensor malfunctions, these findings were confirmed in subsequent expeditions in 2021 and 2022 using alternative measurement techniques.
Sweetman and his team used modules that isolated small sections of the seafloor to measure oxygen levels over several days. They discovered that the water above the metallic nodules became richer in oxygen, contrary to expectations. This phenomenon, termed ‘dark oxygen,’ suggests that the nodules play a crucial role in oxygen production in deep-sea environments.
The oxygen levels recorded were higher than those typically found in algae-rich surface waters. The research highlights the unique and essential function of these polymetallic nodules in the deep-sea ecosystem. However, the exact mechanism of this oxygen production remains unknown, prompting further scientific inquiry.
Implications for Deep-Sea Mining and Environmental Protection
The Clarion-Clipperton Zone is a key target for companies like The Metals Company, which funded the research, due to its abundance of metals like cobalt, nickel, copper, lithium, and manganese. These metals are vital for green technologies such as solar panels and electric car batteries. Scientists estimate that seabed mining could meet up to 45% of the world’s critical metal needs by 2065.
However, the discovery of ‘dark oxygen’ has sparked environmental concerns. The production of oxygen by seabed nodules indicates a complex and poorly understood ecosystem that could be disrupted by mining activities. This has led to calls for more stringent environmental assessments and regulations before proceeding with deep-sea mining projects.
In response to these findings, three civil society groups—Deep Sea Mining Campaign (DSMC), The Ocean Foundation (TOF), and Blue Climate Initiative (BCI)—filed a formal complaint with the US Securities and Exchange Commission (SEC) against The Metals Company. They allege that the company has misled investors and the public about the environmental risks of its operations. Following the complaint, shares of The Metals Company dropped by 5.4%, highlighting the growing scrutiny of deep-sea mining ventures.
This discovery has significant implications for our understanding of deep-sea ecosystems and the potential risks of exploiting them for commercial gain. As scientists continue to explore the depths of our oceans, the need for careful consideration of environmental impacts becomes increasingly crucial.
Source: Mining.com
