The vital role of sulfuric acid in iodine oxoacids nucleation: impacts of urban pollutants on marine atmosphere

Abstract

The nucleation of iodic acid (HIO _3 ) and iodous acid (HIO _2 ) play a significant role in marine new particle formation (NPF) events. However, the inability to explain intensive NPF bursts in polluted coasts indicates the participation of potential precursors. Herein, we identified a novel nucleation mechanism of HIO _3 –HIO _2 system enhanced by the urban pollutant sulfuric acid (H _2 SO _4 ). We found that H _2 SO _4 could largely enhance the cluster formation rates ( J , cm ^−3 s ^−1 ) of HIO _3 –HIO _2 system, especially in high [H _2 SO _4 ] regions near H _2 SO _4 emission sources. The enhanced J of HIO _3 –HIO _2 –H _2 SO _4 system performs better match than that of HIO _3 –HIO _2 system with the observational rates of polluted coasts and polar regions, such as Zhejiang and Marambio. Moreover, the H _2 SO _4 -involved cluster formation is realized without Gibbs free energy barrier and dominate broadly in marine regions with rich H _2 SO _4 and scarce iodine concentrations. These findings may help to explain some missing fluxes of marine new particles and emphasize the impact of urban components on marine nucleation processes.

Keywords

• marine atmospheric aerosols
• new particle formation
• iodine oxoacids nucleation
• air pollutant sulfuric acid