Collaborative Research: Improving our Understanding of Chinese Haze Events by Quantifying the Formation Mechanisms of Sulfate and Nitrate Aerosol in Beijing

极端的城市雾霾在中国很常见，这种污染会长途运输到太平洋和美国，在那里它会损害人类健康和生态系统。因此，了解产生中国雾霾的化学物质对我们很重要。初步数据和分析表明，目前的模型严重低估了中国此次雾霾中的细颗粒物污染。这表明，目前模型中的化学成分是不正确的，我们对它们用于全球评估的预测没有信心。提出的工作将测量北京极端雾霾的化学和同位素组成，并用模型进行分析，以纠正这一问题。研究结果应该可以改善对中国极端空气污染的预测，也可以改善对美国人口暴露的预测，因为这些污染是通过太平洋运输到美国的。研究人员将收集北京城市雾霾中的细颗粒污染样本。这些样品将被带到美国，在那里它们的质量、化学成分（硫酸盐和氮）和细颗粒污染的氧同位素组成将被测量。然后，氧同位素数据将被用于确定放大雾霾颗粒污染的化学机制。美国开发的以北京为中心的高分辨率化学、输运和同位素使能模型将进行调整，以匹配同位素观测结果。这个修正后的模型应该有更好的约束，更真实地捕捉到中国雾霾中测量到的大颗粒产生，以及它们到美国的远程传输。

Extreme urban haze is common in China and this pollution is transported over long range to the Pacific and the United States where it can damage human health and ecosystems. Therefore understanding the chemistry that produces this Chinese haze is important to us. Preliminary data and analysis show that current models grossly under-predict the fine particle pollution in this haze in China. This demonstrates that the chemistry in current models is incorrect and that we do not have confidence in their predictions that are used for assessments worldwide. The proposed work will measure the chemical and isotopic composition of the extreme haze in Beijing and analyze it with models to rectify this problem. The results should improve the forecasting of extreme air-pollution in China and also the exposure to the American population since this is transported over the Pacific to the United States.The researchers will collect samples of fine particle pollution in the urban haze in Beijing. The samples will be brought to US where their mass, chemical composition (sulfate and nitrogen), and the oxygen isotopic composition of the fine particle pollution will be measured. The oxygen isotope data will then be used to fingerprint the chemical mechanisms that are amplifying the particle pollution in the haze. A US developed high-resolution chemistry, transport and isotope enable model centered over Beijing that will be adjusted to match the isotope observation. This revised model should be better constrained and more realistically capture the large particle-production measured in the Chinese haze and also its long-range transport to the United States.