A POSSIBLE FEEDBACK MECHANISM BETWEEN SURFACE IRON AND BOTTOM WATER OXYGEN CONCENTRATIONS
Iron is a limiting micronutrient for phytoplankton controlling production of organic matter in large areas of the ocean. If iron concentrations increase, enhanced export production could increase respiration leading to lower oxygen concentrations in subsurface regions. In turn, observations suggest a threshold of bottom water oxygen concentrations below which iron is massively released from the sediments at the same order of magnitude as phosphate. However, it is not yet known how the sediment release of iron is shaping iron concentrations in the low oxygen water column. If the iron released from the sediments reaches the surface and triggers export production, a feedback mechanism between surface iron concentrations and subsurface oxygen concentrations might exist. Here, we use a global ocean-biogeochemical model to conduct sensitivity studies quantifying the impact and magnitude of this possible feedback mechanism. We show how the iron concentrations and export production at the surface depend on the threshold of bottom water oxygen concentration below which iron is massively released. In addition, we show how the feedback responds to changes in dust deposition and climate warming.
Nickelsen, L., GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany, firstname.lastname@example.org
Oschlies, A., GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany, email@example.com
Time: 16:00 - 18:00
Location: Poster/Exhibit Hall
Presentation is given by student: Yes