HR: 0800h
AN: A11A-0846    [Abstracts]
TI: Characterization of Anthropogenic Magnetic Particles in Asian Dust Using Magnetic Measurements and Electron Microscope Observations in Seoul, Korea: Preliminary Results
AU: * Kim, W
EM: wnkim@korea.ac.kr
AF: Korea University, Dept. of Earth and Environmental Sciences, Seoul, 136-713 Korea, Republic of
AU: Doh, S
EM: sjdoh@korea.ac.kr
AF: Korea University, Dept. of Earth and Environmental Sciences, Seoul, 136-713 Korea, Republic of
AU: Park, Y
EM: aegis@korea.ac.kr
AF: Korea University, Dept. of Earth and Environmental Sciences, Seoul, 136-713 Korea, Republic of
AB: Magnetic measurements and electron microscopic observations have been performed for Asian dust samples in Seoul, Korea, and desert-sand and loess samples in source regions in China to identify pollution of Asian dust by anthropogenic particulates during transportation. Asian dust samples in Seoul have been collected during four Asian dust events occurred in March 19 and 23, April 9, 2002, and April 12, 2003. Desert-sand samples from Khorchin, Lanzhou and Tengel regions, and loess samples from Chifeng region were also collected for comparison during March 2-9, 2003. χ_LF, ARM and SIRM values (magnetic concentration parameters) of Asian dust in Seoul showed 2~288, 2~61 and 2 ~251 times, respectively, higher than those of desert-sand and loess in source regions. This result indicates that Asian dust originated from source regions in China experienced significant influx of magnetic particles during transportation to Seoul, Korea. These magnetic particles added in Asian dust can be recognized as ferrimagnetic minerals (e.g., magnetite and maghemite) based on IRM acquisition patterns and S-ratio values. During the electron microscopic observations for magnetic particles in Asian dust, iron-oxide spherules accompanied by carbon were frequently observed, implying that magnetic contaminants in Asian dust might be originated from fossil fuel combustions. Air- mass backward trajectories during four Asian dust events showed that the air-mass, transporting Asian dust, was originated from the central China and passed through the industrialized eastern China and western Korea on its way to Seoul. Therefore, it can be interpreted that Asian dust in Seoul was highly polluted by anthropogenic magnetic particles originated from industrialized regions in China and Korea. The present study reveals the pollution of Asian dust by anthropogenic particulates during transportation, and suggests that magnetic measurements associated with electron microscopic observations can be used as an useful tool prior to more laborious and expensive chemical analyses in the study of Asian dust.
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0399 General or miscellaneous
DE: 1512 Environmental magnetism
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005