Young-Il Ma

Seasonal Nitrogen Oxides Improvement due to On-road Mobile Air Pollution Source Emission Control Plan in Seoul Metropolitan Area

In order to improve air quality in the Seoul Metropolitan Area (SMA), the “Special Act on Seoul Metropolitan Air Quality Improvement” has been enforced since 2005. The strategy has resulted in some reduction of air pollution, but there has not been much research into the quantitative impact analysis of each separate preventive countermeasure. Therefore, we analyzed nitrogen oxide reduction resulting from implementation of the emission control plan for on-road mobile sources. The MM5SMOKE-CMAQ model system was employed for air quality prediction. Reduced NOx emissions for SMA was 16,561 ton, 4.7% of reduction rate, in 2007. One countermeasure, tighter acceptable standards for manufacturing vehicles, dominated other countermeasures for effective NOx emission control. Large spatial differences in reduced emissions, those for Seoul being twice that of Incheon and Gyeonggi, showed greater NOx emission reduction impact in the heart of the metropolitan complex. The NO2 concentration decreased by 0.60 ppb (2.0%), 0.18 ppb (1.5%), and 0.22 ppb (1.7%) in Seoul, Incheon, and Gyeonggi, respectively. Concentration decreases in spring and winter were larger, 1.5~2.0 times, than summer and fall. However, the NO2 reduction impact did not correspond directly to local NOx emission controls in the city area because of the natural flow and dispersion, both urban and downwind.

Characteristics of Nitrate (NO 3 - ) Volatilization from Fine Particles (PM 2.5 ) at 4 Measurement Sites in Seoul

The purpose of this study is to understand the impact that temperature and relative humidity have on the volatilization loss of particulate nitrate from Teflon filters during measurements of ambient fine particles . Fine particles were measured using an annular denuder system (ADS) at four representive areas in Seoul. The measurements were made during 28 different days at 24-hr sampling intervals from February 14 to October 15, 1997. In this study, nitrate losses. calculated by the ratio of nitrate on the nylon filter to their sum in both Teflon and nylon titters, varied seasonally in the following order: summer (45.5%) > spring (23.8%) > fall (20.6%) > winter (19.7%). The results showed strong correlations with temperature, but we did not observe any significant effects of relative humidity. However, we observed that both temperature and relative humidity influenced the ambient gas/particle nitrate ratio in a different case study using a denuder.