156 / 2024-09-10 12:19:54

Marine aerosol, a good model for multiphase chemistry in the troposphere

marine aerosol

Session 25 - IGAC-SOLAS: Chemistry and physics at surface ocean and lower atmosphere

Marine aerosols, including sea spray aerosols (SSA) and secondary marine aerosols formed by oxidation of volatile organic compounds (such as dimethyl sulfur and isoprene), are ideal candidates in tropospheric multiphase chemistry. The multiphase reactions of SO₂ on the surface of marine aerosols would lead to chlorine depletion of SSA particles. Our study showed that chlorine depletion increased as the concentration of SO₂ increased. In addition, the addition of dimethyl sulfide will further increase the degree of chlorine depletion. SO₂ and NO₂ also have nonlinear effects on the transformation of marine aerosols. NO₂ affects the gas phase mechanism, and SO₂ affects the particle phase mechanism. Under the condition of high relative humidity, the occurrence of heterogeneous reactions of marine aerosols was promoted. It is showed that high relative humidity will increase the particle formation yield, change the reaction path, and increase the liquid phase oxidation. We also investigated key chemical processes at the air-water interface, such as interaction between surface-active substances and persistent organic pollutants and soluble saccharides, which can interact with the surface-active substances to achieve the enrichment in marine aerosols. This interaction can facilitate its air-sea transport and transfer to inland and polar regions. The introduction of persistent organic pollutants also changes the arrangement of the organic film at the SSA interface, which in turn affects a series of heterogeneous chemical processes that occur at the interface.