Properties of individual Asian dust storm particles collected at Kosan, Korea during ACE-Asia

For the purpose of studying the properties of individual Asian dust storm particles, an intensive field measurement took place at the Kosan ground-based station located on the west coast of Cheju Island, Korea during ACE-Asia campaign. A 2-stage filter pack sampler was employed in the size-resolved (coarse and fine fractions) particle sampling. The trace elements of individual coarse particles (>1.2 μm) were analyzed by the X-ray microprobe analysis system equipped at SPring-8. The result of statistical analysis suggested that individual particles collected in Asian dust storm event could be classified into four groups: sea-salt-rich particles, crustal-rich particles, crustal/sea-salt/sulfur-rich particles, and crustal/sea-salt-rich particles. Moreover, according to the XRF elemental maps and elemental masks replayed corresponding to individual particles, particles could be categorized into two groups, namely internally mixed particles and externally mixed particles. A small part of the CaCO3 in Asian dust storm particles would be converted to CaSO4 through the chemical reaction between CaCO3 and H2SO4 during long-range transport. By means of XANES method, the major chemical state of Fe in Fe-rich particles was found to be Fe3+. Several minor trace heavy metals were probably affected by the air masses passed directly over the industrial areas of China.