Measurement report: High contribution of N 2 O 5 uptake to particulate nitrate formation in NO 2 -limited urban areas

作者：Ziyi Lin, Chuanyou Ying, Lingling Xu, Xiaoting Ji, Keran Zhang, Feng Zhang, Gaojie Chen, Lingjun Li, Chen Yang, Yuping Chen, Ziying Chen, Jinsheng Chen · 发表于：Atmospheric chemistry and physics · 年份：2025 · DOI：10.5194/acp-25-17747-2025 · 被引用次数：4 · 研究领域：Atmospheric chemistry and aerosols、Air Quality and Health Impacts、Air Quality Monitoring and Forecasting

Particulate nitrate ( p NO3-) is a major component of fine particles in Chinese urban areas. However, the relative contributions of p NO3- formation pathways in urban areas remain poorly quantified, particularly under the NO 2 -limited regime that governs its formation (as defined by the NO2/O3 ratio), which hinders effective particulate pollution control. In this study, comprehensive winter field observations were conducted in urban Xiamen, Southeast China. We observed significantly elevated nighttime p NO3- levels concurrent with increased N 2 O 5 concentrations. Quantification using an observation-constrained model revealed that N 2 O 5 uptake contributed 51.2 % to total p NO3- formation, which was comparable to that of the OH+NO 2 reaction. The N 2 O 5 uptake was found to be mainly driven by nocturnal NO 3 oxidation capacity (modulated by NO 2 and O 3 levels) rather than by heterogeneous reaction conditions. Sensitivity simulations further demonstrated that p NO3- formation rate was more sensitive to NO x variations than to VOCs variations. Implementing NO x control measures at nighttime was shown to effectively reduce p NO3- by abating N 2 O 5 uptake while simultaneously preventing daytime O 3 increase. Our findings enhance the understanding of p NO3- formation in NO 2 -limited urban areas and provide valuable insights for developing joint PM 2.5 and O 3 mitigation strategies.