View : 77 Download: 0
When and why PM2.5 is high in Seoul, South Korea: Interpreting long-term (2015–2021) ground observations using machine learning and a chemical transport model
- Title
- When and why PM2.5 is high in Seoul, South Korea: Interpreting long-term (2015–2021) ground observations using machine learning and a chemical transport model
- Authors
- Lee; Hyung-Min; Kim; Na Kyung; Ahn; Joonyoung; Park; Seung-Myung; Ji Yi; Yong Pyo
- Ewha Authors
- 김용표; 이형민
- SCOPUS Author ID
- 김용표; 이형민
- Issue Date
- 2024
- Journal Title
- Science of the Total Environment
- ISSN
- 0048-9697
- Citation
- Science of the Total Environment vol. 920
- Keywords
- GEOS-Chem; Nitrate; Nitric acid; rmweather; Seasonal variation; Seoul
- Publisher
- Elsevier B.V.
- Indexed
- SCOPUS; SCIE
- Document Type
- Article
- Abstract
- Seoul has high PM2.5 concentrations and has not attained the national annual average standard so far. To understand the reasons, we analyzed long-term (2015–2021) hourly observations of aerosols (PM2.5, NO3−, NH4+, SO42−, OC, and EC) and gases (CO, NO2, and SO2) from Seoul and Baekryeong Island, a background site in the upwind region of Seoul. We applied the weather normalization method for meteorological conditions and a 3-dimensional chemical transport model, GEOS-Chem, to identify the effect of policy implementation and aerosol formation mechanisms. The monthly mean PM2.5 ranges between about 20 μg m−3 (warm season) and about 40 μg m−3 (cold season) at both sites, but the annual decreasing rates were larger at Seoul than at Baengnyeong (−0.7 μg m−3 a−1 vs. -1.8 μg m−3 a−1) demonstrating the effectiveness of the local air quality policies including the Special Act on Air Quality in the Seoul Metropolitan Area (SAAQ-SMA) and the seasonal control measures. The weather-normalized monthly mean data shows the highest PM2.5 concentration in March and the lowest concentration in August throughout the 7 years with NO3− accounting for about 40 % of the difference between the two months at both sites. Taking together with the GEOS-Chem model results, which reproduced the elevated NO3− in March, we concluded the elevated atmospheric oxidant level increases in HNO3 (which is not available from the observation) and the still low temperatures in March promote rapid production of NO3−. We used Ox (≡ O3 + NO2) from the observation and OH from the GEOS-Chem as a proxy for the atmospheric oxidant level which can be a source of uncertainty. Thus, direct observations of OH and HNO3 are needed to provide convincing evidence. This study shows that reducing HNO3 levels through atmospheric oxidant level control in the cold season can be effective in PM2.5 mitigation in Seoul. © 2024 Elsevier B.V.
- DOI
- 10.1016/j.scitotenv.2024.170822
- Appears in Collections:
- 공과대학 > 화공신소재공학과 > Journal papers
- Files in This Item:
There are no files associated with this item.
- Export
- RIS (EndNote)
- XLS (Excel)
- XML