Water soluble ionic components in high concentrations of suspended particulate matter (SPM) were analyzed to understand secondary inorganic particle formation by using the tape filters of an automatic SPM sampler at a monitoring station in Kawasaki City. In Case I (April 12th to 13th, 2006) and Case II (April 18th to 19th, 2006), the generation and transportation of secondary inorganic particles was discussed considering the relationship between ion concentrations, simultaneously measured gas concentrations, and the results of a back trajectory analysis. In Case I, it was found that NO₃^- concentrations increased and Cl-concentrations decreased in high concentrations of SPM. From these results it was inferred that secondary inorganic particles, mainly formed by HNO₃ gaseous coagulation and condensation into sea salt in humid air, contributed in part to the high concentrations of SPM in the city. In Case II, it was found that SO₄^2- and Ca²⁺ concentrations increased in high concentrations of SPM, and the results of the back trajectory analysis showed that the air mass was transported from the Asian Continent to the Kanto Plain in Japan. Therefore, it has been inferred that the Asian dust from the Asian Continent contributed to the high concentrations of SPM in the city. Also, it was shown that the results from the tape filters and the practical use of relative data were useful in understanding the generation and transportation of secondary inorganic particles.

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Little is known about the characteristics such as detailed compositions and seasonal variations of concentrations of atmospheric VOCs (Volatile Organic Compound) in Japan, even though atmospheric VOCs play an important role in the production of secondary oxidants.
In this paper, seasonal variations of VOCs concentrations were investigated at four sites in the Kansai area, Japan. Five samples were collected at each site in every season and 63 compounds were quantified by GC-MS. The C₄-C₅ species were major components in summer, whereas the C₂-C₃ species had relatively high concentrations in winter. The compositions of VOCs in spring and autumn were roughly intermediate between those of summer and in winter. The ratios of total of quantified compounds to NMHC measured at monitoring stations for air-quality surveillance were about 0.5. It was inferred from rate constants with the OH radical that toluene, xylene, and alkenes, such as ethylene, propene and butene, were major contributors in terms of atmospheric reactivity leading to the production of oxidants. In addition, it was implied that isoprene, which seems to be emitted from biogenic sources, was an important compound in summer. The results of the CMB (Chemical Mass Balance) analysis suggested that gasoline vapor and gasoline vehicle exhaust were significant sources for atmospheric VOCs.

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The relationships between changes in secondary inorganic aerosol concentrations (SIA) and emission reductions in Greater Tokyo were investigated through numerical simulations. First of all, it was confirmed that the numerical model used in the simulations showed an acceptable performance in reproducing measurements. It was shown by analyzing the simulated results that both annual mean concentrations and high-episodic daily concentrations decreased with reduced emissions. The reduction of SIA concentrations appeared mostly in summertime, but the concentrations in wintertime increased with decreasing emissions in some cases. These changes in the SIA concentrations largely depended on the changes in nitrate concentrations.

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We determined the atmospheric dinitrogen monoxide (N₂O) concentration in an open type domestic waste landfill site and a closed system type domestic waste landfill site by continuously using an extractive N₂O analyzer with infrared absorption (infrared N₂O analyzer) and a non-extractive open-path type N₂O analyzer, with infrared absorption (open-path N₂O analyzer), and investigated the increase of nitrous oxide concentration caused by landfill gas.
When the wind was blowing at over 1-2 m/s, the N₂O concentrations ranged from about 0.30 to 0.33 ppm, and they were similar to ordinary concentrations in the urban area. However, when it was blowing at less than 1 m/s or was calm continuously, N₂O emitted from the landfill site could increase the atmospheric N₂O concentrations.
The open-path type N₂O analyzer could show a rough change of N₂O concentration in a small-scale landfill site. Moreover, the N₂O generating speed per unit reclamation area in the landfill site, where residue of crushed incombustible and large size wastes were landfilled, was estimated to be about 60μg/m²·h from the measured increase rate of N₂O concentration.

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[in Japanese]

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