Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany.
Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany.; State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
Sci Adv. 2016 Dec 21;2(12):e1601530. doi: 10.1126/sciadv.1601530. eCollection 2016 Dec.
Fine-particle pollution associated with winter haze threatens the health of more than 400 million people in the North China Plain. Sulfate is a major component of fine haze particles. Record sulfate concentrations of up to ~300 μg m were observed during the January 2013 winter haze event in Beijing. State-of-the-art air quality models that rely on sulfate production mechanisms requiring photochemical oxidants cannot predict these high levels because of the weak photochemistry activity during haze events. We find that the missing source of sulfate and particulate matter can be explained by reactive nitrogen chemistry in aerosol water. The aerosol water serves as a reactor, where the alkaline aerosol components trap SO, which is oxidized by NO to form sulfate, whereby high reaction rates are sustained by the high neutralizing capacity of the atmosphere in northern China. This mechanism is self-amplifying because higher aerosol mass concentration corresponds to higher aerosol water content, leading to faster sulfate production and more severe haze pollution.
细颗粒物污染与冬季雾霾相关，威胁着华北平原 4 亿多人的健康。硫酸盐是细霾颗粒的主要成分。在北京 2013 年 1 月冬季雾霾事件中，观测到高达约 300μg/m 的硫酸盐浓度记录。依赖需要光化学氧化剂的硫酸盐生成机制的最先进空气质量模型，由于雾霾事件期间光化学活性较弱，无法预测这些高水平。我们发现，气溶胶水中的反应性氮化学可以解释硫酸盐和颗粒物缺失的来源。气溶胶水充当一个反应器，其中碱性气溶胶成分捕获 SO，然后被 NO 氧化形成硫酸盐，由此通过中国北方大气的高中和能力维持高反应速率。这种机制具有自我放大作用，因为较高的气溶胶质量浓度对应于较高的气溶胶含水量，导致更快的硫酸盐生成和更严重的雾霾污染。
