Despite the particular conditions of confinement, Chaoyang Xue’s thesis defense took place via videoconference between France and China on Friday, May 15. After 45 minutes of dynamic presentation of his work, he answered precisely during nearly 2 hours to the numerous questions of the jury by animating a high level scientific discussion.
Chaoyang’s thesis was conducted under international co-supervision directed by Prof. Valéry CATOIRE (LPC2E, CNRS-Université d’Orléans), Prof. Yujing MU (RCEES, CAS-University of CAS) and Dr. Gisèle KRYSZTOFIAK (LPC2E, CNRS-Université d’Orléans)
Air pollution is still an environmental problem that urgently needs to be solved in the North China Plain (NCP). With the aim to explore the formation a particular air pollutant, nitrous acid (HONO), and its impact on regional air quality in the NCP, the development of instruments to measure atmospheric HONO concentration and its soil emission flux was performed. Based on field measurements, a tridimensional (3D) numerical model of atmospheric chemistry including the reactions and the air mass transport (CMAQ from EPA, USA) and a box (0D) model (MCM, UK) were used to explore the HONO budget and its impact on regional air pollution, e.g., summer O3 pollution and winter haze pollution. We found that agricultural soil was an important HONO source with a significant impact on regional O3 pollution in the summertime. HONO also plays an important role in atmospheric oxidizing capacity and deteriorating regional air quality.