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        Atmospheric Occurrence of Particle-associated Nitrotriphenylenes via Gas-phase Radical-initiated Reactions Observed in South Osaka, Japan

        Takayuki Kameda,Hiroshi Bandow 한국대기환경학회 2021 Asian Journal of Atmospheric Environment (AJAE) Vol.15 No.1

        Nitrotriphenylenes (NTPs), which include the highly mutagenic isomer 2-nitrotriphenylene (2-NTP), have been detected in airborne particles. From a public hygienic point of view, it is necessary to study the environmental occurrence of NTPs in detail. In this study, concentrations of five nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) including NTPs in airborne particles and of nitrogen oxides (NOx; NO+NO2) and carbon monoxide (CO), at a location in South Osaka, Japan, were measured at 3 h intervals. It was found that the diurnal variations in the concentrations of 1-nitropyrene (1-NP), NOx, and CO were similar, being high early in the morning and late in the evening. This finding indicates that the occurrence of 1-NP is affected significantly by primary emissions, particularly by automotive emissions. The concentration change in 1-nitrotriphenylene was similar to that of 2-nitropyrene produced by an atmospheric OH radicalinitiated reaction. On the contrary, the variations in the concentrations of 2-nitrofluoranthene (2-NF) and 2-NTP were significantly different from those of the other nitro-PAHs, i.e., their concentrations increased during the nighttime, suggesting that neither 2-NF nor 2-NTP was emitted from the primary sources, but were formed via the NO3 radicalinitiated nitration of the parent fluoranthene and triphenylene (TP) in the atmosphere. Based on the ambient concentration of 2-NTP and the reported rate constant for the reaction of TP with NO3 radicals, the yield of 2-NTP from the gas-phase NO3 radical-initiated reaction of TP was estimated to be 23%.

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        Evaluation of Photochemical Pollution during Transport of Air Pollutants in Spring over the East China Sea

        Yasuhiro Sadanaga,Tadashi Kobashi,Akie Yuba,Shungo Kato,Yoshizumi Kajii,Akinori Takami,Hiroshi Bandow 한국대기환경학회 2015 Asian Journal of Atmospheric Environment (AJAE) Vol.9 No.4

        We conducted intensive observations of ozone, CO, NOx (=NO and NO2), NOy (total odd nitrogen species including particulate nitrate) and total nitrate (the sum of gaseous HNO3 and particulate nitrate) at Cape Hedo, Okinawa, Japan, from 19 March to 3 April, 2009, to investigate ozone production during long-range transport from the Asian continent. Ozone production efficiency (OPE) was used to evaluate photochemical ozone production. OPE is defined as the number of molecules of ozone produced photochemically during the lifetime of a NOx molecule. OPE is calculated by the ratio of the concentration increase of ozone to that of NOz (= NOy -NOx). Average OPE during observation was estimated to be 12.6±0.5, but concentrations of ozone increased nonlinearly with those of NOz. This non-linearity suggests that OPE depends on air mass origin and NOz concentrations. There were very different values of OPE for the same air mass origin, so that only the air mass origin alone does not control OPE. OPE was low when NOz concentration was high. We examined the correlation between NOz and CO/NOy ratios, which we used instead of the ratio of nonmethane hydrocarbons (NMHCs) to NOx. The CO/NOy ratios decreased with increasing NOz concentrations. These results indicate that competition reactions of OH with NMHCs and NO2 are the rate determining steps of photochemical ozone production during longrange transport from the Asian continent to Cape Hedo, for high concentrations of nitrogen oxides.

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