In a discovery that could have major implications for deep-sea mining, scientists have found that the highly sought-after metallic nodules resting on the deep sea floor actually help produce oxygen.
A team led by Prof. Andrew Sweetman from the Scottish Association for Marine Science (SAMS) made the discovery during an expedition in the Pacific Ocean, which was published this week in Nature Geoscience.
Sweetman said:
“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. But we now know that there is oxygen produced in the deep sea, where there is no light. I think we therefore need to revisit questions like: where could aerobic life have begun?”
According to SAMS, researchers found nodules to be carrying a very high electric charge, which could lead to the splitting of seawater into hydrogen and oxygen in a process called “seawater electrolysis.” Only a voltage of 1.5 V is needed for seawater electrolysis to occur – the same voltage as a typical AA battery. The team analyzed multiple nodules and recorded readings of up to 0.95 volts on the surfaces of some, meaning that significant voltages can occur when the nodules are clustered together.
Sweetman added:
“Through this discovery, we have generated many unanswered questions and I think we have a lot to think about in terms of how we mine these nodules, which are effectively batteries in a rock.
“When we first got this data, we thought the sensors were faulty, because every study ever done in the deep sea has only seen oxygen being consumed rather than produced. We would come home and recalibrate the sensors but over the course of 10 years, these strange oxygen readings kept showing up.
“We decided to take a back-up method that worked differently to the optode sensors we were using and when both methods came back with the same result we knew we were onto something ground-breaking and unthought-of.”
SAMS Director Prof. Nicholas Owens called the discovery “one of the most exciting findings in ocean science in recent times,” adding:
“The discovery of oxygen production by a non-photosynthetic process requires us to rethink how the evolution of complex life on the planet might have originated. The conventional view is that oxygen was first produced around three billion years ago by ancient microbes called cyanobacteria and there was a gradual development of complex life thereafter.
“The potential that there was an alternative source requires us to have a radical rethink.”
Check out the research findings here.
(Featured image credit: ROV-Team/GEOMAR, CC BY 4.0, via Wikimedia Commons)
