“More than 2.5 billion years ago, at that topographic point was piffling to no oxygen inward the oceans, every bit methyl hydride shrouded the public inward a haze,” says Lu, a fellow member of Syracuse University’s Low-Temperature Geochemistry Research Group. “Organisms practicing photosynthesis eventually started to overpower reducing chemic compounds [i.e., electron donors], too oxygen began edifice upwardly inward the atmosphere. This menses has been called the Great Oxidation Event.”
Using a novel approach called iodine geochemistry, Lu, Zhou too their colleagues accept confirmed the earliest appearance of dissolved oxygen inward the ocean’s surface waters.
Central to their approach is iodate, a shape of iodine that exists exclusively inward oxygenated waters. When iodate is detected inward carbonate rocks inward a marine setting, Lu too society are able to stair out the elemental ratio of iodine to calcium. This measurement, known every bit a proxy for sea chemistry, helps them figure out how much oxygen has dissolved inward the water.
“Iodine geochemistry enables us to constrain oxygen levels inward oceans that accept produced calcium carbonate minerals too fossils,” says Lu, who developed the proxy. “What we’ve constitute inward ancient stone reinforces the proxy’s reliability. Already, we’re using the proxy to amend empathize the consequences of sea deoxygenation, due to rapid global warming.”
In add-on to Lu too Zhou, the article was co-authored past times Dalton S. Hardistry, a graduate pupil at the University of California, Riverside; Noah J. Planavsky, assistant professor of geology too geophysics at Yale University; Andrey Bekker, assistant professor of geological sciences at the University of Manitoba (Canada); Pascal Philippot, professor of physics at the University of Denis Diderot inward Paris (France); too Timothy W. Lyons, professor of biogeochemistry at UC Riverside.