Characteristics of reactive nitrogen compounds and other relevant trace gases in the atmosphere at urban and rural areas of Korea during May–June, 2004.

This study examines the general characteristics of reactive nitrogen oxides (NOy) at urban and rural sites in terms of measurement- and modeling-based analyses. In this field study, NOx at urban and rural sites were 92 and 89% of NOy on average, respectively. HONO levels (e.g., 1.8 ppbv) at the urban site were significantly higher than those at the rural site by a factor of 4.5. HONO concentrations at the urban site during the night were clearly higher than those during the day, which were likely to result from heterogeneous reactions on the surfaces of airborne aerosols and/or grounds. In contrast, there were no significant differences of PAN concentrations in either the temporal or spatial distributions. The significantly low ratios of NOz/NOy at both sampling sites indicated a more limited chemical aging process in air mass. O3 levels were weakly related to NOx oxidation at both sites, especially at the rural site. [ABSTRACT FROM AUTHOR]