Impact of Marine Chlorine Emissions on Secondary Organic Aerosols in North China Plain.

Chlorine radicals (Cl), as important oxidant in the atmosphere, significantly influence the formation of secondary organic aerosols (SOA), which is harmful to air quality and human health. Additionally, marine is an important source of reactive chlorine-containing species that are released into the atmosphere via sea spray aerosols (SSA). To date, the contribution of marine chlorine-containing species on SOA has not been well quantified. Here, we explored and quantified the impact of chlorine-containing species released by SSA on atmospheric oxidants (Cl, OH, HO2, O3), SOA and its main components in the North China Plain (NCP) in 2016 based on a high-resolution chemical transport model (WRF-CMAQ). Model results showed that marine chlorine-containing species emissions have the greatest effect on atmospheric oxidants in summer, and can increase Cl up to 4.53×10-5 ppt, reduce OH, HO2, and O3 up to 0.01 ppb, 0.41 ppb, and 5.30 ppb, respectively. Notably, marine chlorine-containing species emissions decreased O3 generation in each season (up to 1.02 ppb, 3.22 ppb, 5.30 ppb, and 1.58 ppb in winter, spring, summer and autumn, respectively), while promoted SOA formation in winter (0.01 μg/m3) and inhibited in summer (0.01 μg/m3). We also revealed that under high pollution events in winter, marine chlorine-containing species emissions can increase the SOA formation by up to 0.11 μg/m3 due to ClNO2 chemistry (heterogeneous reactions). Our study provides new perspective on the SSA contributions of SOA formation in NCP region.