The Xiamen Symposium on Marine Environmental Sciences (XMAS 2025)

Atmospheric reactive chlorine chemistry plays essential roles in tropospheric photochemical processes, such as affecting the oxidation capacity and aerosol formation. The reactive chlorine chemistry also has been known to be active in the marine atmosphere, and recent studies have indicated that the chlorine chemistry can cause environmental degradation in the coastal cities and throughout the marine atmosphere. Here, we will present the vital chlorine species, such as nitryl chloride (ClNO₂), molecular chlorine (Cl₂), hypochlorous acid (HOCl), hydrochloric acid (HCl) and others that were observed in the marine atmosphere, as well as the recent understanding on their emission and formation via heterogeneous processes. Our recent findings have shown the increasing importance of nocturnal chlorine activation processes in producing ClNO₂ and Cl₂, which ultimately contributing to the haze formation caused by NO_x reduction. Another finding also showed that there is a potential atmospheric chlorine sink process in environment with low temperature and significant bromine chemistry. We will finally discuss the future challenges in the understanding of reactive chlorine chemistry in marine atmosphere under the changing world.

chlorine, atmospheric chemistry, oxidation