Privileged Planet: nitrogen cycle (Introduction)

by David Turell , Tuesday, September 20, 2022, 17:53 (796 days ago) @ David Turell

Import to soil ecosystems:

https://phys.org/news/2022-09-intricacies-nitrogen.html

"Underlying nitrogen's impacts, helpful and harmful alike, is what's known as the nitrogen cycle. That's the collective name for the chemical processes that nature's biological and geological systems use to break down nitrogen compounds and shuttle the products through the environment.

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"At the risk of oversimplifying an entire scientific field, chemistry is concerned with how atoms are exchanged and rearranged when different molecular participants are involved. Some of the most intriguing interactions are those that are essential for life, those that improve our quality of life or those that help scientists better understand how life on this planet works.

"The nitrogen cycle's reactions can check all three boxes, as evidenced by those highlighted in the Warren team's papers.

"'These two reports provide fundamental new insights into molecules that are important parts of the biogeochemical nitrogen cycle. That cycle is critical for ecosystems to work and be healthy," Warren said. "What we're doing is peering into molecules in new ways to better understand their connection to that cycle." (my bold)

"In particular, the team's JACS paper illuminates a new pathway that nature may use to convert nitric oxide into nitrous oxide, which are both important molecules in their own rights.

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"Under the right conditions, nitrous oxide can also be a good electron acceptor, but oxygen provides a steadfast standard in this arena. That's why chemists refer to such electron acceptor compounds as oxidants, oxidizers and oxidizing agents. Oxidizers famously cause metal to rust, but they are also critical to many important biological and industrial reactions.

"But oxygen wasn't a readily available commodity in the Earth's atmosphere until the planet was a couple of billion years old. That's when the first microbes started emitting it, with plants later following suit through photosynthesis.

"'Nature was doing oxidation chemistry before the Great Oxidation Event, before photosynthesis kicked off," Warren said. "That means both nitric oxide and related nitrogen compounds were probably important oxidants in primordial life, before the Earth had a lot of oxygen.

"'It turns out that nature has evolved enzymes that can do that oxidation chemistry with these compounds," he said. "This paper provides new insights on how nature uses them today and perhaps even before oxygen was abundant."

"The team's Nature Chemistry paper focused on a different part of the nitrogen cycle, one that starts with a compound known as nitrite, a negatively charged molecule consisting of a nitrogen atom bound to two oxygen atoms.

"Nitrite shows up in a lot of places, many of which reflect the duality of nitrogen. Nitrite is in fertilizers that help plants grow. It's also in the runoff that pollutes aquatic ecosystems.

"Nitrite is found naturally in healthy levels in fruits and vegetables.

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"Soil microbes have enzymes that convert nitrite to nitric oxide in a highly choreographed set of chemical interactions that happen at the same time."

Comment: nitrogen played a role in the development of life as part of the evolution of Earth into today's form