What Sets the Marine Nitrogen Inventory?

Session ID#: 84910

Session Description:
Fixed nitrogen (N) limits productivity across much of the low-latitude ocean. The magnitude of its inventory results from the balance of N input, mostly biotic N2 fixation, and N loss, occurring in regionally well-defined low-oxygen waters and sediments (denitrification and anammox).

The simple view restricting N2fixation to warm and iron-rich waters has been recently challenged by new evidence demonstrating a wider diversity of N2 fixers and N2 fixation strategies enabling new insights into the controls of this process. However, sources of fixed nitrogen are still unaccounted for, and the mechanisms regulating the response of N2fixers to N deficits are not well understood.

In this tutorial I will discuss how the role of N in controlling ocean productivity has matured. I will review N2 fixation estimates and their uncertainties from experimental, geochemical and modeling approaches. I will discuss the new insights gained into the controls on the marine N2 fixation and the emerging questions on the N inventory regulatory mechanisms, which challenge our current paradigms and place important constraints on our efforts to represent the N cycle in models used for climate predictions. Finally, I will highlight the key challenges that need to be tackled over the coming years.

  • NC - Nutrient Cycling
  • OB - Ocean Biology and Biogeochemistry
  • PC - Past, Present and Future Climate
Index Terms:
Primary Presenter:  Angela Landolfi, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Moderators:  James B Edson, Univ Connecticut, Groton, United States and Carol Anne Clayson, Woods Hole Oceanographic Institution, Physical Oceanography, Woods Hole, MA, United States

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