Zhang receives Simons Early Career Award to study the ocean’s nitrogen producers

Morgan Kelly ・ Princeton Environmental Institute

Xinning Zhang, assistant professor of geosciences and the Princeton Environmental Institute, was among nine scientists nationwide to receive a three-year 2019 Simons Early Career Investigators in Marine Microbial Ecology and Evolution Award from the Simons Foundation. An environmental microbiologist, Zhang’s research focuses on understanding how microbial metabolism influences biogeochemical cycling and climate in modern and ancient environments.

Zhang’s work under the Simons award will explore the physiological diversity and environmental sensitivities of microorganisms known as diazotrophs that live in marine sediment and convert — or “fix” — inert nitrogen gas into more usable ammonium that is crucial to the ecology and function of the ocean. Recent studies have suggested that these sediment organisms, which consist of nitrogen-fixing bacteria and archaea, produce more of the ocean’s ammonium than previously thought. However, the physiology and environmental sensitivities of these diazotrophs are not well understood.

Zhang seeks to understand whether, why and where nitrogen fixation occurs in the ocean. She will apply experimental and modeling approaches to determine the physiological and biophysical conditions that determine nitrogen fixation by marine-sediment diazotrophs. This research could help provide a more thorough understanding of nitrogen budgets at local and regional scales, and improve knowledge of the physiological purpose, metabolic cost and environmental sensitivity of nitrogen fixation in marine systems and beyond.