Iron mobilization in mineral dust and the possible effect of Asian pollution on carbon-uptake in North Pacific Ocean

Eolian transport of dust from arid and semi-arid continental regions is believed to be the main mechanism for delivering mineral iron (Fe) to so-called “high-Nitrate low-chlorophyll” (HNLC) areas of the ocean. HNLC regions are large and potentially important areas of the ocean where the micronutrient Fe appears to limit phytoplankton productivity. Thus, alterations in the flux of Fe to these regions of the ocean may substantially affect ocean productivity and, by changing the rate at which atmospheric CO₂ is fixed by oceanic biota, may even exert a global-scale influence on climate. While Fe must be in soluble form to be utilized by phytoplankton, virtually all Fe in the source-region soils is in highly insoluble, crystalline form. The amount of Fe in dust that is transformed into soluble form or mobilized during transport and deposition to the ocean is not well quantified and the mechanisms responsible for the iron mobilization are not well-characterized.; In this research a combination of diagnostic data analysis and prognostic model calculations is used to investigate Fe mobilization in dust plumes emanating from East Asia during the springtime outflow conditions. A Lagrangian box model of the gas and aqueous-phase chemistry of reactive compounds within an air mass containing mineral dust has been developed. The model, in combination with data from airborne atmospheric chemistry field campaigns carried out over the western Pacific Ocean and the space-borne MODIS and SeaWiFS, is used to assess the viability of acid mobilization triggered by air pollutants from China as a mechanism for producing soluble Fe in mineral dust plumes.