Vehicle exhausts contribute high near-UV absorption through carbonaceous aerosol during winter in a fast-growing city of Sichuan Basin, China. (1st November 2022)

• Record Type: Journal Article
• Authors: Liu, Song; Luo, Tianzhi; Zhou, Li; Song, Tianli; Wang, Ning; Luo, Qiong; Huang, Gang; Jiang, Xia; Zhou, Shuhua; Qiu, Yang; Yang, Fumo
• Is Part Of: Environmental pollution. Volume 312(2022)
• Publication Date: 2022-11-01
• Subjects: Carbonaceous aerosol -- brown carbon -- Light absorption -- Source apportionment -- Vehicle emission; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2022.119966
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Carbonaceous aerosols pose significant climatic impact, however, their sources and respective contribution to light absorption vary and remain poorly understood. In this work, filter-based PM2.5 samples were collected in winter of 2021 at three urban sites in Yibin, a fast-growing city in the south of Sichuan Basin, China. The composition characteristics of PM2.5, light absorption and source of carbonaceous aerosol were analyzed. The city-wide average concentration of PM2.5 was 87.4 ± 31.0 μg/m 3 in winter. Carbonaceous aerosol was the most abundant species, accounting for 42.5% of the total PM2.5 . Source apportionment results showed that vehicular emission was the main source of PM2.5 during winter, contributing 34.6% to PM2.5 . The light absorption of black carbon (BC) and brown carbon (BrC) were derived from a simplified two-component model. We apportioned the light absorption of carbonaceous aerosols to BC and BrC using the Least Squares Linear Regression with optimal angstrom absorption exponent of BC (AAEBC ). The average absorption of BC and BrC at 405 nm were 51.6 ± 21.5 Mm −1 and 17.7 ± 8.0 Mm −1, respectively, with mean AAEBC = 0.82 ± 0.02. The contribution of BrC to the absorption of carbonaceous reached 26.1% at 405 nm. Based on the PM2.5 source apportionment and the mass absorption cross-section (MAC) value of BrC at 405 nm, vehicle emission was found to be the dominant source of BrC in winter, contributing up to 56.4%. Therefore, vehicle emissions mitigation should be the primary and an effective way to improve atmospheric visibility in this fast-developing city. Graphical abstract: Image 1 Highlights: Carbonaceous aerosol was the dominate species of PM2.5 during winter in Yibin city. An improved AAE-based method was applied to evaluate aerosol light absorption. The contribution of BrC to carbonaceous aerosol absorption at 405 nm was 26%. Vehicle emission became the dominant source of BrC in this fast-growing city.