Daellenbach Kaspar R, Cai Jing, Hakala Simo, Dada Lubna, Yan Chao, Du Wei, Yao Lei, Zheng Feixue, Ma Jialiang, Ungeheuer Florian, Vogel Alexander L, Stolzenburg Dominik, Hao Yufang, Liu Yongchun, Bianchi Federico, Uzu Gaëlle, Jaffrezo Jean-Luc, Worsnop Douglas R, Donahue Neil M, Kulmala Markku
Aerosol and Haze Laboratory, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, China.
Institute for Atmospheric and Earth System Research, Faculty of Science, University of Helsinki, Helsinki, Finland.
Nat Geosci. 2024;17(8):747-754. doi: 10.1038/s41561-024-01493-3. Epub 2024 Aug 8.
Haze in Beijing is linked to atmospherically formed secondary organic aerosol, which has been shown to be particularly harmful to human health. However, the sources and formation pathways of these secondary aerosols remain largely unknown, hindering effective pollution mitigation. Here we have quantified the sources of organic aerosol via direct near-molecular observations in central Beijing. In winter, organic aerosol pollution arises mainly from fresh solid-fuel emissions and secondary organic aerosols originating from both solid-fuel combustion and aqueous processes, probably involving multiphase chemistry with aromatic compounds. The most severe haze is linked to secondary organic aerosols originating from solid-fuel combustion, transported from the Beijing-Tianjing-Hebei Plain and rural mountainous areas west of Beijing. In summer, the increased fraction of secondary organic aerosol is dominated by aromatic emissions from the Xi'an-Shanghai-Beijing region, while the contribution of biogenic emissions remains relatively small. Overall, we identify the main sources of secondary organic aerosol affecting Beijing, which clearly extend beyond the local emissions in Beijing. Our results suggest that targeting key organic precursor emission sectors regionally may be needed to effectively mitigate organic aerosol pollution.
北京的雾霾与大气中形成的二次有机气溶胶有关，二次有机气溶胶已被证明对人体健康特别有害。然而，这些二次气溶胶的来源和形成途径在很大程度上仍然未知，这阻碍了有效的污染缓解。在这里，我们通过在北京中心城区进行直接的近分子观测，对有机气溶胶的来源进行了量化。在冬季，有机气溶胶污染主要来自新鲜的固体燃料排放以及源自固体燃料燃烧和水相过程的二次有机气溶胶，这可能涉及与芳香族化合物的多相化学反应。最严重的雾霾与源自固体燃料燃烧的二次有机气溶胶有关，这些气溶胶从京津冀平原和北京西部的农村山区传输而来。在夏季，二次有机气溶胶增加的部分主要由西安 - 上海 - 北京地区的芳香族排放主导，而生物源排放的贡献仍然相对较小。总体而言，我们确定了影响北京的二次有机气溶胶的主要来源，这些来源明显超出了北京本地的排放。我们的结果表明，可能需要在区域层面针对关键的有机前体排放部门，以有效缓解有机气溶胶污染。
