This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Nitrogen is one of life's building blocks, but it's only helpful in the right amounts. Too much nitrogen in water, for example, can lead to poor water quality and the gradual death of aquatic organisms.
Microbes remove nitrogen from water by converting it to a gas that escapes into the atmosphere. But scientists have difficulty determining how much nitrogen is removed this way. Biogeochemists at UC Santa Barbara, UCLA and collaborating institutions have shown that a rare form of nitrogen gas can act as a natural fingerprint for microbial nitrogen conversion.
The study, published in Science, reveals microbial nitrogen loss that conventional methods obscure. The technique requires sophisticated machinery, so it won't find its way into routine field monitoring anytime soon. However, it offers a new tool to improve water-quality assessments and estimates of the global nitrogen budget.
"The problem is that our water naturally has a huge amount of nitrogen gas that is dissolved from the air, so the gas that microbes produce can be very difficult to see," explained first author Jiarui Liu, who conducted the research as a postdoctoral fellow at UCSB's Marine Science Institute and at UCLA. "The answer is written in the way nitrogen atoms are paired inside the nitrogen molecule." Nitrogen is essential for proteins and DNA, yet most organisms can't use nitrogen gas directly from the atmosphere. As nitrogen cycles through air, water and life, some microbes convert the gas into usable compounds while others return those compounds to gas.
The balance between these processes helps determine how much nitrogen is available to support life. However, quantifying these processes has proven challenging. Nitrogen gas, or N2, consists of two nitrogen atoms joined together.
These come in two weights, called isotopes: the common nitrogen-14 and the heavier nitrogen-15, which has one extra neutron. Most N2 molecules contain two nitrogen-14 atoms; some contain one of each isotope; and very rarely, both atoms are nitrogen-15. In atmospheric nitrogen gas, the two heavy nitrogen-15 atoms pair up more often than expected by chance.
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