Dry deposition fluxes and size distributions of heavy metals in Seoul, Korea during yellow-sand events

Mass and elemental dry deposition fluxes and ambient particle size distributions were measured using dry deposition plates and a cascade impactor from March to November 1998 in Seoul, Korea. During the spring sampling period several yellow-sand events characterized by long-range transport from China and Mongolia impacted the area. During these events the mass fluxes were statistically the same as during springtime nonyellow-sand events. However, most elemental fluxes were higher. In general, the flux ratios of both crustal (Al, Ca, Mn) and anthropogenic (Ni, Pb) elements to total mass measured during the daytime yellow-sand events were substantially higher than those measured in spring daytime during nonyellow-sand time periods. During all seasons the average measured daytime fluxes were about two times higher than nighttime fluxes. The flux of primarily anthropogenic metals (Cu, Ni, Pb, Zn) and Mn was on average one to two orders of magnitude lower than the flux of the crustal metals Al and Ca. As is typically found, two modes, fine (0.1 similar to 1.0 mum) and coarse (1.0 similar to 10.0 mum) were present in the measured size distributions (< 10 <mu>m). The particles in the coarse mode constitute a major portion of the measured mass size distribution during the yellow-sand events, possibly due to the long-range transport of those particles from China.