Light absorption enhancement of black carbon from urban haze in Northern China winter. (February 2017)

• Record Type: Journal Article
• Authors: Chen, Bing; Bai, Zhe; Cui, Xinjuan; Chen, Jianmin; Andersson, August; Gustafsson, Örjan
• Is Part Of: Environmental pollution. Volume 221(2017)
• Page Start: 418
• Page End: 426
• Publication Date: 2017-02
• Subjects: Black carbon -- Aerosol mixing states -- Radiative absorption -- Lens effect -- Urban air pollution; 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.2016.12.004
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Atmospheric black carbon (BC) is an important pollutant for both air quality and Earth's energy balance. Estimates of BC climate forcing remain highly uncertain, e.g., due to the mixing with non-absorbing components. Non-absorbing aerosols create a coating on BC and may thereby act as a lens which may enhance the light absorption. However, this absorption enhancement is poorly constrained. To this end a two-step solvent dissolution protocol was employed to remove both organic and inorganic coatings, and then investigate their effects on BC light absorption. Samples were collected at a severely polluted urban area, Jinan, in the North China Plain (NCP) during February 2014. The BC mass absorption cross-section (MAC) was measured for the aerosol samples before and after the solvent-decoating treatment, and the enhancement of MAC ( E MAC ) from the coating effect was defined as the ratio. A distinct diurnal pattern for the enhancement was observed, with E MAC 1.3 ± 0.3 (1 S.D.) in the morning, increasing to 2.2 ± 1.0 in the afternoon, after that dropping to 1.5 ± 0.8 in the evening-night. The BC absorption enhancement primarily was associated with urban-scale photochemical production of nitrate and sulfate aerosols. In addition to that, regional-scale haze plume with increasing sulfate levels strengthened the absorption enhancement. These observations offer direct evidence for an increased absorption enhancement of BC due to severe air pollution in China. Graphical abstract: Highlights: An experimental method determined BC absorption enhancement from PM2.5 pollution. The E MAC rose from 1 to 2 within the photochemical age of one day for urban haze. The E MAC of BC from urban haze peaked at the afternoon. The absorption enhancement was associated with the growth of nitrate and sulfate. Abstract : The atmospheric black carbon radiative forcing is stronger by a factor of 2 from urban air pollution in China.