Annual Variations of the Elemental Concentrations of PM10 in Ambient Air of Nagoya City as Determined by ICP-AES and ICP-MS

PM10 samples were collected at an urban site of Nagoya City during September, 2003, to August, 2004, and annual variations of the concentrations of the elements in PM10 samples were examined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). The annual concentration variations of ca. 30 elements in ambient air were in the range from sub-ng m-3 to several μg m-3. From an evaluation by the enrichment factors of the elements, elements such as Al, Ca, Fe, Mg, Ti, Mn, Ba, Sr, Ce, La, Nd, Co, Cs, and Pr, in PM10 samples were found to have originated mostly from natural sources, while the elements such as S, Zn, Pb, Cu, Ni, Sb, Sn, Cd, Bi, W, Tl, and In originated from anthropogenic emission sources. Furthermore, in seasonal variations of the elemental concentrations of PM10 samples in ambient air, the elements originated mostly from natural sources provided significantly high concentrations in spring during the “Kosa” period (the dust season from March to May). On the other hand, the elements mainly from anthropogenic emission sources provided relatively higher concentrations in autumn and winter, which may be explained by the fact that the urban atmospheric structure is stabilized by the temperature-inversion layer formed over the city in those seasons. In addition, all of the elements provided significantly low concentrations in the summer, due to the dilution effect of the oceanic winds as well as due to the convection of air mass up to the high levels.