Sea spray aerosols (SSAs) are ejected into the atmosphere during wave breaking and bubble bursting at the ocean-air interface. They present extreme environments for chemistry due to their low pH and high ionic strength conditions resulting from water loss and atmospheric aging reactions that quickly acidify nascent SSA. Understanding the pH of these particles is critical in characterizing their environmental impacts and atmospheric reactivity. In addition, because SSAs contain a variety of different classes of organic molecules, including amino acids (AAs), understanding which molecules reside at the aerosol surface is key to understanding the heterogeneous chemistry of aerosols. Here we show through surface tension measurements that the surface activity of amino acids (AAs) increases under the high salt and low pH conditions that are found within SSAs. Additionally, Infrared Reflectance Absorbance Spectroscopy (IRRAS) corroborates these same trends. Salt-driven AA p<i>K</i><sub>a</sub> shifts have been investigated through titration and IR sampling of the bulk solution using attenuated total reflectance-Fourier transform IR (ATF-FTIR) spectroscopy. Preliminary results also suggest that the buffering capacity of SSA-like solutions is reduced compared to pure aqueous solutions, which could contribute to the acidification of SSA. Understanding the physicochemical properties of SSA will help us understand their impact on climate and atmospheric chemistry.

Investigating amino acid surface propensity at the air/water interface

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.