2022년 가을철 충청남도 서산시 대기 중 HONO 분포 및 생성 특성

Nitrous acid (HONO) is a crucial component in atmospheric chemistry, serving as a major source of hydroxyl radicals and a precursor to ozone (O₃) formation, yet its formation mechanisms remain inadequately understood. This study examines the characteristics and formation mechanisms of HONO in a rural area of Seosan, South Korea, during autumn 2022. Real-time measurements revealed that the average HONO concentration was 0.34 ppb, with nighttime levels reaching ~0.42 ppb, which were higher than the daytime average of ~0.23 ppb. These concentrations are comparable to those observed in other rural areas, but significantly lower than urban regions like Seoul. Nighttime HONO formation was strongly influenced by heterogeneous reactions involving nitrogen dioxide (NO₂), relative humidity (RH), aerosol liquid water content (ALWC), and aerosol surface area (S_A). These findings underscore the critical role of heterogeneous processes in HONO production and its subsequent contribution to ozone formation in rural environments. The study highlights the need for further investigation into seasonal variations and the integration of HONO dynamics in air quality management strategies.