In this research, an analytical method was developed for simultaneous measurements of PFCs (perfluorocarbon), HFCs (hydrofluorocarbon), SF₆ (sulfur hexachloride), HCFCs (hydrochlorofluorocarbon), and CFCs (chlorofluorocarbon) in the atmosphere. The analytical system is based on a cryogenic preconcentration with cryocoolers and GC/MS. Temperature programming during the cryogenic concentration and use of a molecular sieve column, have made the system free from the interference by nitrogen and carbon dioxide. Good performance was obtained for the 21 target halocarbons in this study. The relative standard deviation calculated from eight repetitive analyses of 100ppt standard gas was within 2% for most of the target compounds. Detection limits (s/n =2) were lower than 1 ppt for all the compounds except for HFC-32 (1.7ppt). The method was successfully used to study vertical distribution of the target halocarbons over Sagami Bay. The aircraft measurements in August 2003 showed significant vertical difference for HCFC-141 b, HCFC-22, HFC-134a, and CFC-12. The differences of the concentrations at 500m and at 7000m were 636ppt for HCFC-22, 440 ppt for HCFC-141b, 311 ppt for HFC-134a, and 10lppt for CFC-12. It is considered that those vertical profiles reflect the regional emissions of the halocarbons. From the 7000m measurements, the concentretions of HFC-134a and HCFC-22 concentration were found to be 25.2ppt and 157.2ppt in the free troposphere, respectively, showing their continuous increase (ex. HFC-134; 14.6ppt, HCFC-22; 143.2ppt, as of 2000, WMO Ozone Assessment 2002).

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Total OH reactivity was measured by use of a laser-induced pump and probe technique in order to diagnose comprehensively the urban air quality in the suburbs of Tokyo. The concentrations of NO_xCO, O₃, NMHCs (non-methane hydrocarbons) and OVOCs (oxygenated volatile organic compounds) were observed simultaneously. The observations were conducted in July and August 2003, and in January and February 2004. The measured OH loss rates were usually higher than the calculated values, this was derived by using the measured concentrations of the trace species. The difference between the measured and calculated values in the summer observation was approximately 25 %. However, for the winter observation, the difference between the measured and calculated values was less than the difference between the summer values. In addition, while the difference observed in the summer correlated with the concentration of 0₃, no correlations were confirmed in the winter. This suggests that the secondary products of the photochemical reactions in the atmosphere would be a missing sink for the OH loss process.

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Measurable spectral regions of the open light path spectrometer developed by CRIEPI contain absorption bands of volatile organic compounds (VOC) which deeply relate to the formation of SPM that influences human health. In the report, we concentrated on the retrieval of 7 species of VOC, ozone, and sulfur dioxide. In the retrieval procedures, gas concentrations were determined by correlated linear least-squares fit, and a correction for the oxygen absorption structure was added to ensure higher accuracy of the retrieval results. For the evaluation of the retrieved concentrations, comparisons were carried out with gas concentrations that were simultaneously measured from directly trapped atmosphere. The results of the comparisons showed good correlations for all species excepting one VOC that existed as an undetectable concentration between the measurement periods. Furthermore, time variations of the retrieved VOC concentrations corresponded with those of the nitrogen oxide concentration of mobile exhaust emission are most likely the largest contributor.

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Fog waters and precipitations were collected at the top of Mt. Yahiko, which is located in the westerm part of the Niigata Plane. Precipitations were also collected at the foot of Mt. Kakuda, which lies about 9 km northeast of Mt. Yahiko. Major ion constituents and nitrogen isotope ratios of ammonium and nitrate ions were measured. The sea-salt constituents in both the fog waters and the precipitations increased in winter. The concentration of major ion constituents was roughly, in order from lower to higher, mountaintop's precipitation, mountain foot's precipitation and fog water. The collected-water weighed mean of nitrogen isotope ratios of ammonium ions (δ¹⁵N-NH₄⁺) in the fog waters, the mountaintop's and the mountain foot's precipitations was -3.0, -1.8 and -4.0 %o, respectively. The δ¹⁵N-NH₄⁺ values of the mountain foot's precipitation were lower than those of the mountaintop's precipitation, especially in May and June. This may be the result of the absorption of ammonia gas (NH₃) which has lower (δ¹⁵N) values when emitted from agricultural activities and so on. On the other hand, the mean of nitrogen isotope ratios of nitrate ions (δ¹⁵N-NO₃^-) in the fog waters, the mountaintop's and the mountain foot's precipitation was -3.0, -4.5, -4.4 ‰, respectively. The o δ¹⁵N-NO₃^- values of the mountaintop's precipitation were nearly equal to those of the mountain foot's, and the values of the fog waters were somewhat higher than those of the precipitations. The monthly mean of δ¹⁵N-NO₃^- in these three kinds of samples showed almost the same monthly variations and were higher in winter.

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