Introduction
As one of the typical secondary air pollutants in photochemical smog and an important constituent of odd nitrogen in the atmosphere, peroxyacetyl nitrate (PAN) significantly influences nitrogen cycle and atmospheric chemical processes. The whole process of formation, transport and decomposition of PAN presents to be an important pathway of ozone (O3) transport on regional and even hemispheric scale. In recent years, urban O3 pollution has been increasing across the country. Central China where the economy is developing rapidly also experiences severe O3 pollution. However, research on photochemical air pollution lags behind.
This project focuses on chemical processes and impacts on O3 formation of PAN in high-altitude background atmosphere of Central China. The scientific questions in relation to (i) Chemical processes of PAN under high-altitude meteorology and high biogenic emissions; and (ii) Role of PAN in regional transport of O3 and transfer of atmospheric oxidation capacity will be answered. Field observation of PAN will be carried out at Shennongjia that is known as "Roof ridge of Central China", and in-situ modelling of chemical processes and regional transport modelling will be performed. The objectives are to determine the concentrations and sources of PAN in both the boundary layer and free troposphere, reveal the chemical processes of PAN at the level of radical chain reactions, and quantify the impacts of surrounding city clusters on O3 pollution and atmospheric oxidation capacity in Central China through PAN transport. The project will enhance our understanding on PAN chemistry in high-altitude background atmosphere and facilitate regional joint control of O3 pollution.
过氧乙酰硝酸酯（PAN）是大气光化学污染的典型二次污染物之一，奇氮的重要组成部分，显著影响大气化学过程。PAN的生成、传输和分解是区域乃至半球尺度臭氧（O3）传输的重要途径。近年来，我国城市O3污染日益加剧。华中地区经济发展迅速，O3污染严重，而大气光化学研究较为滞后。本项目聚焦华中地区高海拔背景大气中PAN的化学过程及对O3生成的影响，拟解决两个关键科学问题：1. 高海拔气象条件和高植物源排放下PAN的化学过程；2. PAN在O3区域传输和大气氧化性转移中扮演的角色。项目拟于素有"华中屋脊"之称的神农架林区开展PAN的外场观测、原位光化学模拟和区域传输模拟，从而厘清PAN的浓度特征和来源，在自由基链反应层面揭示PAN化学过程，并量化周边城市群以PAN为媒介对华中地区O3和大气氧化性的影响。项目将深化关于高海拔背景大气中PAN化学过程的认识，推进O3污染区域联合治理。