Scientists turn the tables on old truth about nitrogen mixing in oceans

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Washington, September 3 (ANI): A Princeton University-led team of scientists has turned the tables on a long-standing controversy to re-establish an old truth about nitrogen mixing in the oceans.

For decades, scientists thought they had a handle on the workings of an intricate natural mechanism known as the nitrogen cycle, essential to maintaining life on Earth.

This process, one of nature's most elegant sleights-of-hand, shuttles nitrogen from the soils to the oceans to the atmosphere and back.

A key part of that cycle, researchers once thought, was a process known as denitrification.

In low-oxygen - or anaerobic - conditions seen in large stretches of ocean sediments and in a few important regions of the open ocean, bacteria act as "denitrifyers," performing the crucial task of gobbling up nitrates and converting them to nitrogen gases, which complete the cycle by flowing back to the atmosphere.

In 1995, a group of Dutch scientists who had been studying the cycling of nitrogen through wastewater treatment plants came up with a startling conclusion.

A new process, which they called anaerobic oxidation or "anammox" and that involved different bacteria, was the real player in removing nitrogen in low-oxygen environments, they said.

They found the process worked to break down materials in sewage, and they confirmed that the mechanism also was operating in low-oxygen marine environments.

They went so far as to suggest that the nitrogen cycle for oceans needed to be revised, as denitrification, according to their inquiry, did not play the major role that had been thought.

The notion was controversial and did not sit well with some scientists.

Now, a research team, led by Bess Ward, the William J. Sinclair Professor of Geosciences at Princeton University, is presenting data that could re-establish denitrification as the main actor in returning nitrogen to the air.

After traveling through some of the key low-oxygen sites of the world's oceans, the team has found the telltale chemical signatures proving that denitrification and not anammox is the pivotal process at work most of the time.

"In our paper, we report that in the world's largest anoxic marine ecosystem - the low-oxygen waters of the Arabian Sea - denitrification rather than anammox is the dominant process," said Ward.

"If denitrification is important in the Arabian Sea, then it is important on a global scale, and the nitrogen cycle must be evaluated in that light," Ward added. (ANI)

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