Enrichment of Perfluoroalkyl Acids on Sea Spray Aerosol in Laboratory Experiments: The Role of Dissolved Organic Matter, Air Entrainment Rate and Inorganic Ion Composition

Abstract

The process by which perfluoroalkyl acids (PFAAs) become enriched on sea spray aerosol (SSA) is complex and likely influenced by several factors. In this study, we utilized a plunging water jet in a controlled laboratory setup to generate SSA. We investigated the enrichment process of PFAAs on nascent SSA by systematically varying three key parameters: 1) total organic carbon (TOC), 2) water jet flow rate, and 3) inorganic ion composition. The results showed a significant enhancement in enrichment when organic matter was introduced into artificial seawater. However, this enhancement did not exhibit a consistent trend when increasing the TOC from 1 to 2 mg L-1. The enrichment was increased at higher water jet flow rates (3.2 L min-1) compared to lower flow rates (1.6 and 2.4 L min-1), and the effect was particularly pronounced for submicrometer SSA particles. There was minimal difference in the enrichment of PFAAs when SSA was generated using sodium chloride solution instead of artificial seawater at the same salinity. Overall, these findings shed light on the complex process of PFAA enrichment on SSA and improved our understanding of the uncertainties associated with varying dissolved organic matter, water jet flow rate, and inorganic ion composition.