Evidence of oceanic ’green rust’ offers hope for the future

A rare kind of mineral which scientists hope could be used to remove toxic metals and radioactive species from the environment played a similar, crucial role early in Earth's history. Research carried out by an international team of leading biogeochemists suggests for the first time that ‘green rust’ was likely widespread in ancient oceans and may have played a vital role in the creation of our early atmosphere. Led by Newcastle University, UK, the study shows that during the Precambrian period, green rust ‘scavenged’ heavy metals such as nickel out of the water. Nickel availability is linked to the production of methane by anaerobic organisms, which is a major sink for oxygen produced during photosynthesis, and thus green rust played a crucial role in the oxygenation of the Earth’s atmosphere. Only discovered in the last decade, green rust is a highly reactive iron mineral which experts hope could be used to clean up metal pollution and even radioactive waste. Newcastle University’s Professor Simon Poulton, who will take up a new position in September as a Leadership Chair in the Faculty of Environment at the University of Leeds, said this latest discovery – published in the academic journal Geology – proved the effectiveness of green rust as an environmental cleaner. “Because it is so reactive, green rust has hardly ever been found before in nature and never in a water system like this,” explains Professor Poulton, who led the research team involving experts from the Universities of Newcastle, Nancy, Southern Denmark, Leeds, Brussels and Kansas, and the Canadian Light Source and Indonesian Institute of Sciences.