Marine Submicron Aerosols from the Gulf of Mexico: Polluted and Acidic with Rapid Production of Sulfate and Organosulfates

• DOI: 10.1021/acs.est.2c05469
• Publication Date: 2023-03-20T15:01:18Z
• Authors: Shan Zhou; Fangzhou Guo; Chun-Ying Chao; Subin Yoon; Sergio L. Alvarez; Sujan Shrestha; James H. Flynn; Sascha Usenko; Rebecca J. Sheesley; Robert J. Griffin
• Keywords: Aerosols; Air Pollutants; Gulf of Mexico; China; haze formation; Sulfates; Environmental Studies; Sulfur Oxides; marine aerosol; organic sulfate; 6. Clean water; Engineering; 13. Climate action; aqueous-phase processing; Sustainability and Environmental Research; Particulate Matter; 14. Life underwater; secondary organic aerosol (SOA); Oxidation-Reduction; Environmental Monitoring

We measured submicron aerosols (PM1) at a beachfront site in Texas in Spring 2021 to characterize the "background" aerosol chemical composition advecting into Texas and the factors controlling this composition. Observations show that marine "background" aerosols from the Gulf of Mexico were highly processed and acidic; sulfate was the most abundant component (on average 57% of total PM1 mass), followed by organic material (26%). These chemical characteristics are similar to those observed at other marine locations globally. However, Gulf "background" aerosols were much more polluted; the average non-refractory (NR-) PM1 mass concentration was 3-70 times higher than that observed in other clean marine atmospheres. Anthropogenic shipping emissions over the Gulf of Mexico explain 78.3% of the total measured "background" sulfate in the Gulf air. We frequently observed haze pollution in the air mass from the Gulf, with significantly elevated concentrations of sulfate, organosulfates, and secondary organic aerosol associated with sulfuric acid. Analysis suggests that aqueous oxidation of shipping emissions over the Gulf of Mexico by peroxides in the particles might potentially be an important pathway for the rapid production of acidic sulfate and organosulfates during the haze episodes under acidic conditions.