서울시 도로변, 터널 및 주거지역 대기 중 유해 휘발성 유기화합물의 특성

Abstract

Hazardous volatile organic compounds (HVOCs) have been increasingly getting concern in urban air chemistry due to photochemical smog as well as its toxicity or potential hazards. In this study, we investigated their concentrations and the properties in tunnel, urban roadside and residential area. As a result, among 36HVOCs measured in this study, BTEX (benzene, toluene, ethylbenzene, xylene) and dichlorodifluoromethane, 1,2,4-trimethylbenzene, trichlorofluoromethane were detected above the concentration of <TEX>$1{\mu}g/m^3$</TEX> in every sampling site and the most abundant compound was toluene. The other compounds were detected at trace level or below the detection limit. In addition, we found that three CFCs (chlorofluorocarbons), such as CFC-12, CFC-11, CFC-113, were persistently detected because of the emission in the past. Toluene to benzene ratio (T/B) at tunnel and roadside were calculated to be 4.3~5.3 and at residential area 15.4, suggesting that the residential area had several emission sources other than car exhaust. The ratio of X/E (m,p-xylene to ethylbenzene) ratio was calculated to be 1.8~2.1 at tunnel, 1.7 at roadside and 1.2 at residential area, which means this ratio reflected well the relative photochemical reactivity between these compounds. Good correlation between m,p-xylene and ethylbenzene (<TEX>$r^2$</TEX> > 0.85) were shown in every study sites. This indicated that correlation between <TEX>$C_2$</TEX>-alkylbenzenes were not severely affected by 3-way catalytic converter. In this study, it was demonstrated that the concentration of benzene was very low, compared with national air quality standard (annual average of <TEX>$5{\mu}g/m^3$</TEX>). Its concentration were <TEX>$2.52{\mu}g/m^3$</TEX> in roadside and <TEX>$1.34{\mu}g/m^3$</TEX> in residential area. We thought this was the result of persistent policy implementation including the reduction of benzene content in gasoline enforced on January 1, 2009.