GESAMP Study on the Atmospheric Input of Chemicals to the Ocean: Iron Atmospheric Processing

This presentation summarizes conclusions of a study on atmospheric deposition of chemicals to the ocean, evaluated by the UN Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) in collaboration with the World Meteorological Organization. We focus on the importance of deposition of the iron-carried dust aerosol responsible for marine production. The GESAMP study recommends more effort to understand major components of the Fe atmospheric cycle, including physical aerosol size sorting, mineral composition at emission and Fe processing during the atmospheric transport.

In this presentation, we will also show results produced by a regional dust-iron model developed to simulate the Fe atmospheric solubilization. The iron solubility, a necessary form for marine production, is low at soil dust sources, but during the atmospheric transport the solubility increases due to Fe atmospheric exposition. The chemical decay rate for transforming iron to soluble form is parameterized in the model to depend on the iron mineralogy at soil sources. It is also a function of cloud processing and solar radiation (Fe photo-reduction). We compare the model results with the Fe solubility observations collected during several Central Atlantic research cruises. on 7-19-2012-->