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Yin-Yang of Nitrogen: #NSFCareer Researcher Amy Marcarelli

The balance of nitrogen fixation and denitrification is not a perfect yin-yang. Unbalanced systems can lead to more than just August pond scum; excess nitrogen is the main driver of the world's dead zones at major river deltas.Amy Marcarelli's research, funded by an NSF CAREER grant, dives into the unexplored side of nitrogen fixation in stream


  1. Over the next summer, @AmyMarcarelli will be leading a team across North America, gathering samples in streams from Puerto Rico to Alaska to get a better sense of nitrogen fixation. Stay tuned on @mturesearch and to learn about the team's work. Here's a local stream where they'll sample.
  2. This is a recap of a live chat with @AmyMarcarelli and @mturesearch from March 17, 2016.
  3. Meet the Processes

  4. @AmyMarcarelli's work focuses on two processes in the nitrogen cycle: nitrogen fixation and denitrification. In undisturbed natural ecosystems, the processes balance each other out, with each part of the cycle driven by certain microbial communities. In a nutshell: nitrogen gas gets converted (via nitrogen fixation) into a new form of nitrogen (ammonium), which is transformed into another kind (nitrate), and is finally changed again and released back into the atmosphere (via denitrifcation.)
  5. Here are a quick explainer:
  6. Amy Marcarelli: Denitrification TL;DR
  7. The Balancing Act

  8. Within this big global biogeochemical cycle, @AmyMarcarelli is interested in how nitrogen fixation and denitrifcation are balanced.
  9. The Other Players

  10. Nitrogen is a major nutrient that organisms need to survive. However, it's not the only nutrient.