Extraction and characterization of surfactants in coastal seawater and atmospheric aerosol particles from Skidaway Island, GA

Surfactants are surface active organic molecules that lower the surface tension of a solution. They are derived from both natural and anthropogenic sources, which contribute to their concentrations in surface seawaters, estuaries, and atmospheric aerosol particles. Surfactants in seawater, especially in the surface microlayer, can affect the exchange of gases across the air-sea interface. This is largely due to the influence of surfactants on the surface tension of the water surface. Additionally, surfactants and their influence on surface tension can also play a role in bubble bursting processes at the ocean surface and affect the emission of primary marine aerosols and their resulting composition. The role of surfactants in these processes may be dependent on their concentrations, compositions, and potential to reduce surface tension. This study demonstrates an efficient extraction technique using multiple solid phase extractions to separate and concentrate surfactants from estuary water and collocated coastal atmospheric aerosol particle samples. The composition of the extracted surfactants was characterized with electrospray ionization coupled with an ion trap mass spectrometer (ESI-IT-MS). Using surfactant standards, we measured extraction efficiencies of greater than 75%, 75%, and 50% for anionic, cationic, and nonionic surfactants, respectively. We applied these techniques to characterize surfactants in estuary water and atmospheric aerosol particles collected at the Skidaway Institute of Oceanography outside of Savannah, Georgia during May and June of 2018. We observed clear signatures of cationic surfactants, in addition to nonionic and anionic surfactants, in both the aerosol particles and the estuary water. Here we compare the surfactant mass spectral signatures in atmospheric aerosol particles and in the estuarine waters over daily cycles to infer marine sources of surfactants in the aerosol particles.