Interface-Mediated Modulation by Anion-Rich Sea Spray Microdroplets to CO2 Fixation

Sea spray aerosol (SSA) contains abundant anions, which significantly impact CO 2 fixation at the air-water interface in atmospheric microdroplets. However, the underlying molecular mechanism remains unclear. Herein, we simulated SSA using nebulized saltwater microdroplets and investigated the common SSA anions (Cl − , Br − , I − , and SO 4 2− ) intervening in the abiotic carboxylation of succinate with CO 2 at the interface. The combination of online and offline analyses revealed that the SSA anions inhibited the interfacial carboxylation of succinate, with an inhibitory effect inversely proportional to their concentration. Kinetic studies confirmed that the carboxylation reaction occurred at a relatively high rate in the presence of the SSA anions. Furthermore, a mechanistic investigation was performed, which showed that SSA anions inhibited the interfacial carboxylation of succinate by modulating the interfacial electric field. Additionally, the formation of adducts between halogen anions from SSA and succinate suggests a potential pathway for the accumulation of succinate in the early marine environment. This work advances our understanding of air-water interfacial chemistry and provides new insights into prebiotic chemistry in the marine atmosphere.