Scientists who recently discovered that clumps of metal at the bottom of the dark sea produce oxygen have announced plans to study the deepest parts of Earth's oceans in order to understand the strange phenomenon.
The researchers say their mission could “change the way we look at the possibility of life on other planets as well.”
The initial discovery baffled marine scientists. It was previously accepted that oxygen could only be produced through sunlight by plants, in a process called photosynthesis.
If oxygen – a vital element for life – is made in the dark by mineral clumps, researchers believe this process could occur on other planets, creating oxygen-rich environments where life can flourish.
Lead researcher Professor Andrew Sweetman explained: “We are already in conversation with experts at NASA who believe dark oxygen could reshape our understanding of how life might persist on other planets without direct sunlight.
“We want to go there and find out exactly what's going on.”
The initial discovery sparked a worldwide scientific debate, and there was controversy Criticism of results From some scientists and from deep-sea mining companies that plan to harvest precious metals in seafloor nodules.
If oxygen is produced at these extreme depths, in complete darkness, it calls into question what life can survive and thrive on the sea floor, and what impact mining activities could have on that marine life.
This means that seabed mining companies and environmental organizations – some of which claimed the findings provided evidence that seabed mining plans should be halted – will be watching this new investigation closely.
The plan is to work in locations where the seafloor is more than 10 kilometers (6.2 miles) deep, using remotely operated submersible equipment.
“We have tools that can reach the deepest parts of the ocean,” Professor Sweetman explained. “We're pretty confident we'll find this happening elsewhere, so we'll start investigating why that is.”
Some of these experiments, in collaboration with scientists at NASA, will aim to understand whether the same process could allow microscopic life to flourish beneath oceans on other planets and moons.
“If there is oxygen, there could be microbial life taking advantage of that,” Professor Sweetman said.
Biologically puzzling preliminary results were published last year In the Journal of Natural Earth Sciences. They come from several expeditions to a deep-sea area between Hawaii and Mexico, where Professor Sweetman and his colleagues sent sensors down to the sea floor – at a depth of about 5 kilometers (3.1 miles).
This area is part of a wide area of seafloor covered in naturally occurring mineral nodules, which form when minerals dissolved in seawater collect on shell fragments – or other debris. It is a process that takes millions of years.
Sensors deployed by the team repeatedly showed rising oxygen levels.
“I ignored it because I had learned that you only get oxygen through photosynthesis,” Professor Sweetman told BBC News at the time.
Eventually, he and his colleagues stopped ignoring their readings and instead began to understand what was happening. Experiments conducted in their laboratory – with nodules collected by the team submerged in beakers of seawater – led the scientists to conclude that the mineral blocks were producing oxygen from seawater. They found that the nodules generate electrical currents that can split (or decompose) seawater molecules into hydrogen and oxygen.
Then came the backlash, in the form of rebuttals – posted online – from scientists and seabed mining companies.
One critic, Michael Clarke of Minerals, a Canadian deep-sea mining company, told BBC News that the criticism centered on “a lack of scientific rigor in the experimental design and data collection.” Essentially, he and other critics claimed that there was no oxygen production, just bubbles produced by the equipment while collecting samples.
Professor Sweetman responded: “We have ruled out that possibility.” “But these (new) experiments will provide the evidence.”
This may seem like a niche technical argument, but several multi-billion-pound mining companies are already exploring the possibility of harvesting tons of these minerals from the seabed.
The natural deposits they target contain minerals vital for making batteries, and demand for those minerals is growing rapidly as many economies transition from fossil fuels to electric cars, for example.
The race to extract these resources has raised concern among environmental groups and researchers. More than 900 marine scientists from 44 countries participated I signed a petition Highlighting environmental risks and calling for a halt to mining activity.
Speaking about his team's latest research mission at a press conference on Friday, Professor Sweetman said: “Before we do anything, we need – as much as possible – to understand the (deep-sea) ecosystem.
“I think the right decision is to wait before we decide whether this is the right thing to do as a global community.”
