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Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments

Peng, Jianfei and Hu, Min and Guo, Song and Du, Zhuofei and Zheng, Jing and Shang, Dongjie and Zamora, Misti Levy and Zeng, Limin and Shao, Min and Wu, Yu-Sheng and Zheng, Jun and Wang, Yuan and Glen, Crystal R. and Collins, Donald R. and Molina, Mario J. and Zhang, Renyi (2016) Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments. Proceedings of the National Academy of Sciences of the United States of America, 113 (16). pp. 4266-4271. ISSN 0027-8424. PMCID PMC4843448.

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Black carbon (BC) exerts profound impacts on air quality and climate because of its high absorption cross-section over a broad range of electromagnetic spectra, but the current results on absorption enhancement of BC particles during atmospheric aging remain conflicting. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China, and Houston, United States, using a novel environmental chamber approach. BC aging exhibits two distinct stages, i.e., initial transformation from a fractal to spherical morphology with little absorption variation and subsequent growth of fully compact particles with a large absorption enhancement. The timescales to achieve complete morphology modification and an absorption amplification factor of 2.4 for BC particles are estimated to be 2.3 h and 4.6 h, respectively, in Beijing, compared with 9 h and 18 h, respectively, in Houston. Our findings indicate that BC under polluted urban environments could play an essential role in pollution development and contribute importantly to large positive radiative forcing. The variation in direct radiative forcing is dependent on the rate and timescale of BC aging, with a clear distinction between urban cities in developed and developing countries, i.e., a higher climatic impact in more polluted environments. We suggest that mediation in BC emissions achieves a cobenefit in simultaneously controlling air pollution and protecting climate, especially for developing countries.

Item Type:Article
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URLURL TypeDescription Information CentralArticle
Wang, Yuan0000-0001-6657-8401
Molina, Mario J.0000-0003-2339-3225
Zhang, Renyi0000-0001-8708-3862
Additional Information:© 2016 National Academy of Sciences. Freely available online through the PNAS open access option. Contributed by Mario J. Molina, February 16, 2016 (sent for review October 2, 2015; reviewed by Zhanqing Li and Yangang Liu). Published online before print March 28, 2016. We thank Wei Hu and Zhaoheng Gong for their assistance with the AMS data analysis, Wentai Chen and Yue Li for providing VOCs data, and Nan Ma for providing the core−shell code for the Mie calculation. This work was supported by National Natural Science Foundation of China (Grants 91544214 and 21190052), the National Basic Research Program, China Ministry of Science and Technology (Grant 2013CB228503), National Natural Science Foundation of China (Grant 21190052), and the China Ministry of Environmental Protection’s Special Funds for Scientific Research on Public Welfare (Grant 20130916). R.Z. acknowledges support from the Robert A. Welch Foundation (Grant A-1417) and Houston Advanced Research Center. Author contributions: R.Z. designed research; J.P., S.G., Z.D., Jing Zheng, D.S., Y.-S.W., Jun Zheng, Y.W., C.R.G., and R.Z. performed research; M.H., L.Z., M.S., D.R.C., M.J.M., and R.Z. contributed new reagents/analytic tools; M.H., S.G., M.L.Z., M.J.M., and R.Z. analyzed data; and J.P., M.H., M.J.M., and R.Z. wrote the paper. Reviewers: Z.L., University of Maryland, College Park; and Y.L., Brookhaven National Laboratory. The authors declare no conflict of interest. This article contains supporting information online at
Funding AgencyGrant Number
National Natural Science Foundation of China91544214
National Natural Science Foundation of China21190052
Ministry of Science and Technology (China)2013CB228503
Ministry of Environmental Protection (China)20130916
Robert A. Welch FoundationA-1417
Houston Advanced Research CenterUNSPECIFIED
Subject Keywords:black carbon; absorption; air quality; radiative forcing; climate
Issue or Number:16
PubMed Central ID:PMC4843448
Record Number:CaltechAUTHORS:20160329-073130543
Persistent URL:
Official Citation:Jianfei Peng, Min Hu, Song Guo, Zhuofei Du, Jing Zheng, Dongjie Shang, Misti Levy Zamora, Limin Zeng, Min Shao, Yu-Sheng Wu, Jun Zheng, Yuan Wang, Crystal R. Glen, Donald R. Collins, Mario J. Molina, and Renyi Zhang Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments PNAS 2016 113 (16) 4266-4271; published ahead of print March 28, 2016, doi:10.1073/pnas.1602310113
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:65723
Deposited By: Tony Diaz
Deposited On:29 Mar 2016 15:10
Last Modified:09 Mar 2020 13:19

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