Green rust may have played a crucial role in the creation of Earth’s early atmosphere suggests new research into the highly reactive mineral.
The mineral rarely occurs in nature as it reacts quickly in oxygen to produce common rust, but green rust was likely widespread in ancient oceans where it played a key role in the oxygenation of Earth’s atmosphere.
An international team have shown that during the Precambrian period, green rust scavenged heavy metals like nickel from water – a principle they hope to apply to remove toxic metals and radioactive species from today’s environment.
Availability of nickel is linked to methanogenisis by anaerobic organisms – a major sink for oxygen produced during photosynthesis, thus green rust was critical in the creation of the early atmosphere.
“Because it is so reactive, green rust has hardly ever been found before in nature and never in a water system like this,” said Professor Simon Poulton from Newcastle University, who led the research. “The discovery of green rust in Lake Matano shows for the first time what a key role it played in our ancient oceans – scavenging dissolved nickel, a key micronutrient for methanogenesis.”
“We still know relatively little about green rust but our research shows that it is likely to be much more prevalent in the environment than has previously been recognised and the role it plays in cycling elements such as nickel and other elements is significant,” said Dr Sean Crowe from the University of Southern Denmark.
“Understanding the important role it played in our past and its effectiveness at removing metals from the environment will help us to understand how we might be able to use it to clean up polluted land and water in the future.”
Researchers hope that green rust may reduce elements like chromium, uranium and selenium at polluted sites, significantly reducing their solubility and mobility in the environment.
“Green rust has received a lot of attention recently due to its possible role as a pollutant mediator, but it is particularly exciting to think that this may have been a natural process throughout huge periods of ancient Earth history,” said Poulton.