Abstract
The atmospheric aerosols were investigated from April 2003 to March 2006 at Maebashi and Mt. Akagi, both of which are located on the inland Kanto plain. Fine (< 2.1 μm) and coarse (2.1 - 11 μm) particles were collected using an Andersen low-volume air sampler, and the organic carbon (OC), elemental carbon (EC), and ionic components were measured. The mean mass concentrations of the fine particles were 21.7 and 9.4 μg/m3 at Maebashi and Akagi, respectively. The highest concentration of fine particles was observed in spring; nitrate and sulfate were the major components. Sulfate and OC were dominant in summer and fall. Nitrate and sulfate were present in the form of ammonium nitrate and ammonium sulfate, respectively. We compared the concentrations of the ionic components in the fine particles collected at Maebashi and Akagi and found that the distribution of ammonium sulfate was widespread, while that of ammonium nitrate was localized to Maebashi. The localized distribution of ammonium nitrate at Maebashi was attributed to the high concentration of gaseous ammonia in this region and transport of gaseous nitric acid from the southern Kanto area. The mass concentration of fine particles was estimated by a chemical mass closure model. The ammonium nitrate, ammonium sulfate, and organic aerosols accounted for a large fraction of the total mass of the fine particles in the inland Kanto area.
