New Discovery in the Deep Sea: Metallic Minerals Produce Oxygen

An international team of researchers, including a chemist from Northwestern University, has made an astonishing discovery deep beneath the ocean’s surface. They found that metallic minerals located on the seafloor, at depths of about 13,000 feet, are producing oxygen.

This groundbreaking research goes against the long-standing belief that only photosynthetic organisms—like plants and algae—generate oxygen for Earth. Instead, it turns out that the dark, lightless regions of the deep sea can also produce this vital gas, creating oxygen that supports the life of aerobic creatures in complete darkness.

The exploration leading to this advance was carried out by the Scottish Association for Marine Science (SAMS). One of the researchers, Dr. Ailsa Sweetman, who leads the Seafloor Ecology and Biogeochemistry research group at SAMS, expressed that this discovery could alter our understanding of the origins of life on Earth. “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,” she explained. “But we now know that there is oxygen produced in the deep sea, where there is no light.”

A central feature of this revelation lies in the polymetallic nodules, which are natural mineral deposits on the ocean floor. These interesting formations are made up of a mix of various metals and can range in size from tiny grains to around the size of a potato.

Dr. Franz Geiger, co-author of the study and a professor of chemistry at Northwestern University, shed light on the significance of these nodules. “The polymetallic nodules that produce this oxygen contain metals like cobalt, nickel, copper, lithium, and manganese, which are all critical elements used in batteries,” he stated. The implications of this discovery raise pressing questions regarding the ongoing deep-sea mining efforts targeting these materials.

Many large mining companies are eyeing the extraction of these precious metals from the ocean floor at depths ranging from 10,000 to 20,000 feet. Geiger emphasized the need to reconcile these mining endeavors with the preservation of oceanic life, suggesting a more thoughtful approach to resource extraction to ensure the oxygen source for deep-sea ecosystems remains intact.

The researchers’ journey began in the Clarion-Clipperton Zone, a unique underwater ridge that stretches nearly 4,500 miles across the northeastern Pacific Ocean. As the research team sampled the seabed, they were taken aback when they found oxygen in an area so deep underwater.

Initially, the findings seemed too extraordinary to be true. They thought their sensors might be malfunctioning, given that previous studies had only documented oxygen consumption in the deep sea. For a decade, curious readings kept appearing, raising the question of whether they might have stumbled upon a new phenomenon.

The breakthrough came when Sweetman proposed to Geiger that they explore the hypothesis of the oxygen source further. Geiger’s expertise in electrochemistry led to crucial insights about the potential of these nodules. “It turns out that when rust combines with saltwater, it can generate electricity,” Geiger elaborated. “We wondered whether these nodules could create enough electricity to liberate oxygen.”

For the next phase of their investigation, Sweetman sent several pounds of the polymetallic nodules back to Geiger’s lab at Northwestern. This partnership allowed them to experiment further and explore the interaction between the nodules and seawater.

The results were remarkable. Just a small voltage—a mere 1.5 volts, similar to a typical AA battery—is sufficient to split seawater into hydrogen and oxygen. In their lab work, the team measured voltages of up to 0.95 volts on individual nodules. The combination of several nodules resulted in even more significant voltages, similar to how batteries can enhance power when connected in series.

Geiger felt a sense of discovery excitement, referring to the nodules as natural “geobatteries.” This term encapsulates a fascinating aspect of their research and helps explain how oxygen may be produced in the dark realms of the sea.

With their findings published in Nature Geoscience, the implications extend beyond scientific knowledge to urgent questions regarding the future of deep-sea mining. As the world looks to secure resources to meet the energy demands for emerging technologies, such as electric vehicles, the race to mine these polymetallic nodules is heating up.

Experts believe that the Clarion-Clipperton Zone holds enough nodules to satisfy the global demand for essential metals needed in batteries for decades. However, Geiger urges caution, drawing attention to the possible long-term consequences of mining efforts.

Reflecting on the history of marine mining during the 1980s, Geiger pointed out that the marine life in areas affected by mining did not recover. “In 2016 and 2017, marine biologists visited sites that had been mined back in the 1980s and found not even bacteria had recovered in those areas,” he said. “In contrast, regions that remained unmined showed thriving marine life.”

This information provides a sobering reminder of the complexities involved in underwater mining. The scientists argue that regions rich in polymetallic nodules may be just as diverse as the most vibrant tropical rainforests, highlighting the crucial need for responsible and sustainable practices in deep-sea operations.

As researchers continue to explore the depths of the ocean, they are likely to uncover more secrets about the interconnected ecosystems thriving 13,000 feet below. What remains clear is that the findings surrounding the production of oxygen by metallic minerals not only challenge existing knowledge but also may influence future environmental policies as we navigate the fine balance between resource extraction and ecological preservation.