Scientists who recently discovered that iron lumps in the dark ocean form oxygen, have announced plans to study the deepest parts of the Earth’s oceans to understand this strange phenomenon.
Their mission “could change the way we look at the possibility of life on other planets,” the researchers said.
The first discovery puzzled marine scientists. Previously it was accepted that oxygen can only be produced from sunlight by plants – through a process called photosynthesis.
If oxygen – an essential component of life – is made in the dark from metal lumps, researchers believe the process may be happening on other planets, creating oxygen-rich environments where life can thrive.
Lead researcher Professor Andrew Sweetman explained: “We are already talking to NASA experts who believe that dark oxygen could change our understanding of how life can be sustained on other planets without direct sunlight.
“We want to go out and find out what’s really going on.”
The first discovery caused a worldwide scientific row – there was critique the findings to other scientists and deep-sea mining companies that plan to harvest precious metals from the layers of the ocean floor.
If oxygen is produced at this extreme depth, in total darkness, it calls into question what organisms can live and thrive on the sea floor, and what effect mining activities can have on those marine life.
That means offshore mining companies and environmental groups – some of which say the findings provide evidence that offshore mining plans should be halted – will be watching the new investigation closely.
The plan is to operate in areas where the ocean is more than 10km (6.2 miles) deep, using remotely operated underwater equipment.
“We have instruments that can go deep into the ocean,” explained Prof. Sweetman. “We’re sure we’ll find it happening somewhere else, so we’ll start investigating what’s causing it.”
Some of that research, in collaboration with Nasa scientists, will aim to understand whether the same process could allow for life that is not well seen beneath the oceans of other planets and moons.
“If there is oxygen,” said Prof. Sweetman, “there will be small animals that take that.”
The first, biologically puzzling findings were published last year in the journal Nature Geoscience. They came from several trips to the deep ocean between Hawaii and Mexico, where Prof. Sweetman and his colleagues sent sensors to the bottom of the ocean – about five kilometers (3.1 miles) deep.
That area is part of a mass of seafloor covered with naturally occurring iron nodules, which form when metals dissolved in seawater collect on pieces of shell – or other debris. It is a process that takes millions of years.
Sensors the team has planted repeatedly show oxygen levels rising.
“I just ignored it, Prof Sweetman told BBC News at the time, “because I was taught that you only get oxygen through photosynthesis”.
Eventually, he and his colleagues stopped ignoring their studies and began to understand what was going on. Experiments in their lab – with nodules the team collected submerged in seawater – led the scientists to conclude that the metal lumps were forming oxygen in the seawater. The bubbles, they found, produce electrical currents that can split (or electrolyse) seawater molecules into hydrogen and oxygen.
Then came the backlash, in the form of objections – posted online – from scientists and undersea mining companies.
One of the critics, Michael Clarke of the Metals Company, a Canadian deep-sea mining company, told BBC News that the criticism centered on “the lack of scientific rigor in the design of the tests and the collection of data”. In fact, he and other critics say there is no oxygen production – just bubbles produced by machines during sample collection.
“We’ve ruled that out,” replied Prof Sweetman. “But these [new] the test will give evidence.”
This may seem controversial, but multi-billion dollar mining companies are already exploring the possibility of harvesting tons of these metals from the ocean floor.
The natural deposits they target contain metals essential to making batteries, and demand for those metals is growing rapidly as many economies shift from fossil fuels to, for example, electric cars.
The race to extract those resources has caused concern among environmental groups and researchers. More than 900 marine scientists from 44 countries signed the petition highlighting the risks to the environment and calling for a temporary halt in mining operations.
Speaking about his research team’s latest work at a press conference on Friday, Prof Sweetman said: “Before we do anything, we need – as best we can – to understand [deep sea] ecosystem.
“I think the right decision is to stop before we decide if this is the right thing to do as a global community.”
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