Abstract
Iron (Fe) is an essential element for marine phytoplankton growth. Long-range transport of atmospheric aerosols from the continent and subsequent deposition is an important process to supply Fe to the ocean. The mixing states with water-soluble materials are the significant factor for the dry and wet depositions of aerosol particles. In this study, we focused on water-insoluble Fe-containing particles and clarified the mixing states with water-soluble materials. We collected aerosol particles on the R/V Hakuho Maru in the mid-latitude over the North Pacific Ocean. Collected particles were analyzed using a transmission electron microscopy with a water dialysis method and an energy-dispersive X-ray (EDX) analysis. Particles larger than 0.5 μm in diameter during a dust event and no dust events (maritime and continental sample) were analyzed. The number fractions of water-insoluble material containing particles to total analyzed particles were 10% (maritime), 20% (continental) and 30% (dust event), respectively. Most of water-insoluble materials were mixed with water-soluble materials. Based on EDX analyses of water-insoluble materials in analyzed 3 samples, water-insoluble Fe-containing particles were found with other mineral components (Si or Al) and the number fractions of Fe-containing particles to total analyzed particles were 2% (maritime), 2% (continental) and 8% (dust events), respectively.
