HR: 0830h
AN: GP41B-0047 [PDF]
TI: Preliminary Results of Two-Year Magnetic Monitoring of Roadside Dust in Seoul, Korea
AU: * Kim, W
EM: wnkim@korea.ac.kr
AF: Korea University, Department of Earth and Environmental Sciences, Seoul, 136-701
Korea, Republic of
AU: Doh, S
EM: sjdoh@korea.ac.kr
AF: Korea University, Department of Earth and Environmental Sciences, Seoul, 136-701
Korea, Republic of
AU: Park, Y
EM: aegis@korea.ac.kr
AF: Korea University, Department of Earth and Environmental Sciences, Seoul, 136-701
Korea, Republic of
AB:
Various mineral magnetic measurements for roadside dust samples have been carried out in Seoul, Korea, in order to reveal the
spatial and temporal pollution features based on magnetic properties of dust. A total of 1,956 dust samples were collected
monthly from June 1998 to June 2000 at eight locations divided into industrial areas, heavy traffic density areas and a park
area. The major magnetic phase of the roadside dust was identified to be ferrimagnetic minerals, based on the results of
S-ratio, isothermal remanent magnetization (IRM) acquisition pattern and hysteresis parameters. Spatial and temporal
variations of magnetic concentrations were traced using the values of low field susceptibility ($\chi_{LF}$), anhysteretic
remanent magnetization (ARM) and saturation IRM (SIRM). Spatially, samples from the industrial areas show the highest values
of each parameter, whereas those from a park area show the lowermost ones. Samples from the heavy traffic density areas
reveal relatively low to intermediate value ranges. The highest content of magnetic materials in samples from the industrial
areas can be attributed to input of the high fraction of magnetic materials emitted from nearby factories. Temporally,
magnetic concentration parameters indicate that the magnetic concentration in the roadside dust is relatively higher in
winter (the dry season) than in summer (the rainy season). These temporal variations of magnetic concentrations could
represent the increase of fossil fuel uses in winter time. In addition, the extensive influence of the Asian dust can be
detected by the maximum magnetic concentration in March, 2000. Spatial and temporal variations of magnetic grain sizes of
dust were determined by interparametric ratios of ARM/$\chi_{LF}$ and ARM/SIRM. There are no distinctive spatial differences
in the study area. However, values of ARM/$\chi_{LF}$ and ARM/SIRM are high in summer and low in winter, indicating that the
mean grain size of magnetic materials in dust is relatively coarser in winter than in summer. This temporal pattern of
magnetic grain size in dust can be ascribed to the increase of coarse-grained magnetic materials from anthropogenic sources
during winter time and to the washout effect of coarse grains by heavy rainfalls during summer time. Geochemical analyses
(Cr, Cu, Fe, Mn, Pb and Zn) for selected samples were performed to examine any relationship between heavy metals and magnetic
parameters. Some of the analyzed elements (Cr, Cu, Fe and Zn) show similar spatial pattern to those of magnetic
concentration parameters such as $\chi_{LF}$, ARM and SIRM. Especially, the concentrations of Cr, Cu, Fe and Zn show
relatively high correlation coefficient (R$^{2}$ = 0.68-0.90) with $\chi_{LF}$. These results suggest that mineral magnetic
parameters can be used as rapid proxy indicators for the degree of heavy metal pollution in urban areas, and that a
combination of magnetic and geochemical methods provide more complete information than would be obtained by an individual
method.
DE: 1500 GEOMAGNETISM AND PALEOMAGNETISM
DE: 1512 Environmental magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2003 Fall Meeting