Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 10333-10348, 2017
https://doi.org/10.5194/acp-17-10333-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
04 Sep 2017
Ageing and hygroscopicity variation of black carbon particles in Beijing measured by a quasi-atmospheric aerosol evolution study (QUALITY) chamber
Jianfei Peng1,2, Min Hu1,3, Song Guo1,2, Zhuofei Du1, Dongjie Shang1, Jing Zheng1, Jun Zheng2, Limin Zeng1, Min Shao1, Yusheng Wu1, Don Collins2, and Renyi Zhang1,2 1State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China
2Department of Atmospheric Sciences, Texas A&M University, College Station, Texas, 77843, USA
3Beijing Innovation Center for Engineering Sciences and Advanced Technology, Peking University, Beijing, 100871, China
Abstract. Measurements of ageing and hygroscopicity variation of black carbon (BC) particles in Beijing were conducted using a 1.2 m3 quasi-atmospheric aerosol evolution study (QUALITY) chamber, which consisted of a bottom flow chamber through which ambient air was pulled continuously and an upper reaction chamber where ageing of BC particles occurred. Within the reaction chamber, transmission of the solar ultraviolet irradiation was approximately 50–60 %, wall loss of primary gaseous pollutants was negligible, and BC exhibited a half-lifetime of about 3–7 h. Typically, equilibrium for the primary gases, temperature and relative humidity between the reaction chamber and ambient air was established within 1 h. Rapid growth of BC particles occurred, with an average total growth of 77 ± 33 nm and average growth rate of 26 ± 11 nm h−1. Secondary organic aerosols (SOA) accounted for more than 90 % of the coating mass. The O ∕ C ratio of SOA was 0.5, lower than the ambient level. The hygroscopic growth factor of BC particles decreased slightly with an initial thin coating layer because of BC reconstruction, but subsequently increased to 1.06–1.08 upon further ageing. The κ (kappa) values for BC particles and coating materials were calculated as 0.035 and 0.040 at the subsaturation and supersaturation conditions, respectively, indicating low hygroscopicity of coated SOA on BC particles. Hence, our results indicate that initial photochemical ageing of BC particles leads to considerable modifications to morphology and optical properties but does not appreciably alter the particle hygroscopicity in Beijing.

Citation: Peng, J., Hu, M., Guo, S., Du, Z., Shang, D., Zheng, J., Zheng, J., Zeng, L., Shao, M., Wu, Y., Collins, D., and Zhang, R.: Ageing and hygroscopicity variation of black carbon particles in Beijing measured by a quasi-atmospheric aerosol evolution study (QUALITY) chamber, Atmos. Chem. Phys., 17, 10333-10348, https://doi.org/10.5194/acp-17-10333-2017, 2017.
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Short summary
Rapid growth of BC particles was observed in Beijing using a new outdoor chamber, with an average growth rate of 26 ± 11 nm h−1. Secondary organic aerosol (SOA) accounted for more than 90 % of the coating mass. The hygroscopic growth factor of BC particles increased to 1.06–1.08 upon ageing. The κ (kappa) values for BC particles were calculated as only 0.035, indicating that initial photochemical ageing of BC particles does not appreciably alter the particle hygroscopicity in Beijing.
Rapid growth of BC particles was observed in Beijing using a new outdoor chamber, with an...
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