[SEM18-11] Negative correlation between concentration of iron oxides and particulate matter in atmospheric dust at industrial site during smoggy period
キーワード：magnetite, air pollution, PM10, correlation
Environmental magnetism, focusing on ferrimagnetic iron oxides, provides useful additional information on pollution of different environments. These methods have been applied to studies of atmospheric dust, namely PM10 (particulate matter smaller than 10 micrometers) in, e.g., industrial or urban areas. Until now, positive correlation was reported between concentration of iron oxides (expressed in terms of either magnetic susceptibility, saturation remanent or induced magnetization) and concentration of PM10 or smaller. In this study, we examined 24-hours PM10 and PM1 samples, collected during 20 days of smoggy winter period at a site close to steel works, which represents a significant source of atmospheric emissions in industrial region of Northern Moravia, known for generally high degree of air pollution. Our data show striking negative correlation between saturation magnetization and both PM1 and PM10 concentration, the trend not being reported yet. This finding may seemingly disqualify magnetic methods as useful proxy in air pollution studies. However, we suggest that this is an exceptional case, specific to this region and monitoring site, which is close to the source of atmospheric dust emissions. Although the significant dust emissions are presumably rich in iron oxides, the overall air quality at the monitoring site is determined by the general environment, controlled by other sources in the region, and by the specific climatic conditions. Thus, the nearby steel works dominate the deposited dust in the nearby site only during very few days of suitable weather.