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Syracuse University professor makes major impact with research about how oxygen came to Earth’s atmosphere

Rachel Gilbert | Development Editor

Chris Junium, an assistant professor in the earth sciences department at SU, and his team have discovered details of the Great Oxidation Event, including that it occurred over a period of time rather than on a set date.

At the entrance to Chris Junium’s geology lab at Syracuse University are an airlock and a pile of lab shoes.

As he removed his shoes and slipped on one of the clean pairs, Junium, an assistant professor in the earth sciences department at SU, explained it’s a precaution meant to limit the amount of dust that enters the lab. That allows him to better analyze nitrogen as part of his research aimed at learning more about the Great Oxidation Event.

The Great Oxidation Event, which Junium has researched in collaboration with an international team of geologists over the span of the last 10 years, concerns the period in Earth’s history when oxygen first flooded the atmosphere. The researchers recently had their research published in a science journal.

By using technology he developed in Syracuse, Junium and his team have discovered more specific details of the event, including that it occurred over a period of time rather than on a set date.

“What’s unique about the specific aspects of the study is that we’re following what happens to nitrogen across this transition in Earth’s history, over this several-hundred-million-year period,” he said.

The team is led by Aubrey Zerkle, who works in the School of Geography & Geosciences at the University of St. Andrews in the United Kingdom. Aside from Junium and Zerkle, the team is also comprised of geologists from the University of Leeds in England and the University of California, Riverside. Their research was recently published in Nature, an international weekly journal of science.

Using 2.31-billion-year-old core samples of shale discovered in South Africa and Australia, the team has tracked the samples’ chemistry with nitrogen isotopes. Nitrogen is a building block of genetic material and is sensitive to the presence or absence of oxygen. In the presence of oxygen, nitrogen will oxidize and leave a signature.

The technology developed by Junium allows him to test small samples of nitrogen, which helped the team identify changes in the nitrogen isotopes, which in turn allowed them to date the Great Oxidation Event.

The shale samples are in their core igneous states, meaning they’ve been left unchanged throughout time, which makes them the most useful for geologic research.

Junium said he felt relieved and excited when he learned that the team’s research paper was going to be published.

“To get something into a publication like this, it means that it’s totally new research,” Junium said. “(The research uncovered) new ideas in a very exciting time period.”

Now that the research has been published, it can be used to further analyze the relationship of climatic changes to life, said Andrey Bekker, an assistant professor at U.C. Riverside and a geologist on the team who is mainly devoted to field work.

“We’re trying to understand what happened, and how the appearance of oxygen (in the ocean and atmosphere) related to all the changes in the environment, like the assembly and breaking up of continents, climatic changes and changes in the chemistry of the ocean and atmosphere,” Bekker said.

Bekker also said the new research “makes things complicated, but it makes them exciting.”

There are still unanswered questions concerning the Great Oxidation Event that Zerkle — the lead scientist — said she and other geologists will likely spend their careers exploring. One question geologists are now attempting to answer is why the Great Oxidation Event happened when it did, Zerkle said in an email.

“(This research) is simply us trying to understand this Earth,” Junium said. “It’s a natural sort of thing to try to do to understand your home. In the same way that people study American history to understand the context of our place in the world, geologists do that in the deep time to try to understand our place in the universe.”

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