The physical properties of mineral aerosols and their transfer to the ocean surface

Atmospheric transport, in the troposphere, is responsible for large fluxes of mineral material from the continents to the ocean. The importance of aeolian dust transport from the continents to the oceans has been debated over recent years. Part of the debate concerns whether the flux of mineral aerosol from the continents to the ocean can be extensive enough to effect biological processes especially in high nutrient/low productivity open ocean surface waters (Martin et al. 1991; Young et al 1991; Duce & Tindale 1991). Geologists have become interested in dust plumes also studying the mass transport of mineral particles with respect to desertification.; Particles collected range in size from under 0.05 μm to as much as 150 μm diameter dependent only on filter pore size. Dust particles can typically be transported up to 10,000 km via the free troposphere and marine boundary layer before settling out to the ocean surface. This study of mass transport of mineral aerosol (dust particles) is intended to compare the results from two separate areas, the Eastern Equatorial Pacific and the Arabian Sea.; Accurate studies of the fluxes of aeolian dust are sparse. Global aerosol fluxes are estimates based on what little data that does exist (Duce et al. 1991). How aerosols move through the atmosphere, their path and settling characteristics form an important part in understanding global ocean atmosphere interaction. This experiment collects suspended mineral aerosol from the two regions proposed and analyzes them with two methods of analysis, X-ray Mapping (XRM) and Computer Controlled Scanning Electron Microscopy (CCSEM). X-ray mapping is a new technique allowing particle size range detection of between 1–50 μm, allowing the detection of super-particles.; Detailed particle size and composition analysis is undertaken and particles are studied on a particle-by-particle basis for both size and composition distributions within the suspended material mass. These fluxes are then used to calculated particle addition to the mixed layer of the ocean at the two regions considered and hence dissolved iron contribution from these particles to surface waters.