Sea Surface Temperature: A Key Regulator of Global Perfluoroalkyl Acids Transport across the Sea–Air Interface

Perfluoroalkyl acids (PFAAs), particularly perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS), can be emitted into the atmosphere via sea spray aerosols (SSA), contributing to long-range airborne transport of pollutants. However, the role of sea surface temperature (SST) in modulating this emission remains unclear. This study systematically investigates the impact of SST on PFAAs enrichment in SSA using laboratory experiments and global emission modeling. Results show that higher SST can significantly promote the enrichment of PFAAs in SSA (particularly in submicrometer SSA), due to increased bubble collision efficiency and surface-active behavior of PFAAs. The enrichment factors (EFs) at 25 °C were 1–2 orders of magnitude higher than those at 4 °C, with a stronger SST dependence for longer-chain PFAAs. When considering SST effects, the estimated global emission fluxes of PFOA and PFOS are approximately 3.1 and 2.7 times the previously calculated values, respectively. These findings highlight SST as a critical regulator of PFAAs sea–air transfer, emphasizing the need to integrate temperature-dependent enrichment mechanisms into global models for accurate assessment of atmospheric PFAAs transport and environmental impact.