Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, U.K.
College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QE, U.K.
Environ Sci Technol. 2022 Jun 7;56(11):7163-7173. doi: 10.1021/acs.est.2c00650. Epub 2022 Apr 28.
The interaction between water vapor and atmospheric aerosol leads to enhancement in aerosol water content, which facilitates haze development, but its concentrations, sources, and impacts remain largely unknown in polluted urban environments. Here, we show that the Indian capital, Delhi, which tops the list of polluted capital cities, also experiences the highest aerosol water yet reported worldwide. This high aerosol water promotes secondary formation of aerosols and worsens air pollution. We report that severe pollution events are commonly associated with high aerosol water which enhances light scattering and reduces visibility by 70%. Strong light scattering also suppresses the boundary layer height on winter mornings in Delhi, inhibiting dispersal of pollutants and further exacerbating morning pollution peaks. We provide evidence that ammonium chloride is the largest contributor to aerosol water in Delhi, making up 40% on average, and we highlight that regulation of chlorine-containing precursors should be considered in mitigation strategies.
水汽与大气气溶胶的相互作用导致气溶胶含水量增加，从而促进了雾霾的形成，但在污染的城市环境中，气溶胶的浓度、来源和影响在很大程度上仍不清楚。在这里，我们表明，污染最严重的首都城市中排名第一的印度首都德里，也经历了全球范围内有记录以来最高的气溶胶含水量。这种高气溶胶含水量促进了气溶胶的二次形成，使空气污染更加严重。我们报告说，严重的污染事件通常与高气溶胶含水量有关，高气溶胶含水量会增强光散射，使能见度降低 70%。强烈的光散射也抑制了德里冬季早晨的边界层高度，阻碍了污染物的扩散，进一步加剧了早晨污染高峰。我们提供的证据表明，氯化铵是德里气溶胶含水量的最大贡献者，平均占比为 40%，并强调在缓解策略中应考虑含氯前体的监管。
