Measurement of atmospheric formaldehyde and monoaromatic hydrocarbons using differential optical absorption spectroscopy during winter and summer intensive periods in Seoul, Korea

A Long-Path DOAS (LP-DOAS) developed by GIST was used to measure simultaneously atmospheric formaldehyde, monoaromatic hydrocarbons, and other trace gases over 740 and 2000 m beam paths at an urban site in Seoul, Korea during two field campaigns in February and August 2003. The mean concentrations of formaldehyde, benzene, toluene, m-xylene and p-xylene were measured to be 6.32 (± 2.41), 0.78 (± 0.32), 3.32 (± 1.87), 0.52 (± 0.24), and 0.38 (± 0.18) ppbv during the two measurement periods. Based on the analysis of the ratio of the OH -NO^sub 2^ to OH -VOCs rate constants, it was possible to draw a conclusion that OH reacted preferentially with NO^sub 2^ during the two measurement periods. Diurnal variation of formaldehyde was not typical of photochemically generated components during the two measurement periods in Seoul. Results from the linear regression fit analysis and diurnal variation of the measured species support that formaldehyde measured could be from primary sources (vehicle exhaust and heating burners) in winter and from primary and secondary sources (photochemical process) in summer. Monoaromatic hydrocarbons were likely emitted from the primary sources.[PUBLICATION ABSTRACT]