The synergistic effects of methanesulfonic acid (MSA) and methanesulfinic acid (MSIA) on marine new particle formation

Marine aerosols have significant impacts on the global radiation balance and climate. New particle formation (NPF) is an essential source of aerosol formation. Sulfur-containing acids (sulfuric acid (SA), methanesulfonic acid (MSA), and methanesulfinic acid (MSIA)) oxidized from ocean-emitted dimethyl sulfide (DMS), have been identified as nucleation precursors in marine NPF. Given their homology, these sulfur species are likely to contribute jointly to the NPF. However, the joint effects of such sulfur acids on NPF and the nucleating mechanism remain unknown. Hence, the first quaternary SA-MSA-MSIA-DMA nucleation system was systematically investigated under different conditions using density functional theory (DFT) combined and Atmospheric Cluster Dynamic Code (ACDC). The results indicate that MSA and MSIA can synergistically enhance the formation rates of SA-dimethylamine (DMA) clusters, especially in regions with low temperatures, sparse SA and DMA. In the mid-latitude oceans, MSA and MSIA can jointly promote nucleation by forming SA-MSA-DMA and SA-MSIA-DMA clusters like ‘division of cooperation’. While in the cold polar regions, MSA and MSIA can synergistically enhance clustering via forming stable MSA-MSIA-based clusters like ‘hand in hand’. The proposed quaternary SA-MSA-MSIA-DMA mechanism manifests itself more effectively in the nucleation process, and such a multi-component nucleation model may help us to understand the frequent marine NPF more comprehensively.