UC San Diego

Contaminants like plastics, pharmaceuticals, illicit drugs, and personal care products enter the oceans directly or indirectly from land runoff, rivers, and atmospheric deposition. While known to accumulate at the ocean surface, the efficiency of transfer into sea spray aerosols (SSA) at the ocean-air interface and their atmospheric lifetime once airborne is relatively understudied. Photosensitizing materials found in marine dissolved organic matter may lead to enhanced photochemical removal of pollutants. A complete analysis of these pollutants' transfer and environmental fate is warranted to improve our collective understanding of the full impact of human activities on public and ecological health. Additionally, the full complexity of the natural coastal marine atmosphere remains poorly understood, compounding the difficulty in isolating and understanding the impacts of anthropogenically introduced materials. Secondary marine aerosol (SMA) formed from the oxidation and condensation of biogenically emitted gases drives marine cloud formation, which may serve as a natural buffer system for human-caused climate change. Deepening our understanding of these complex systems requires detailed characterization of the organic compounds that constitute polluted and natural marine aerosols.

Our findings identify SSA as an important vector for transporting several illicit drugs, personal care products, and plastic additive compounds from the ocean to the atmosphere. Quantifying selected contaminants in aerosol and water samples across multiple coastal sites in San Diego revealed a regional hotspot near the Tijuana River outflow, with the amount of pollutants transferred into SSA dependent on their ocean concentration and lipophilicity. This airborne pathway underscores the need for revised health assessments in polluted coastal regions due to the heightened exposure risk for coastal residents and visitors.

An investigation of the photo-induced degradation kinetics of the toxic sunscreen ingredient oxybenzone (BP3) in seawater and SSA mimics reveals rapid degradation in aerosols compared to bulk solutions. Despite this rapid degradation, the formation of toxic transformation products suggests sustained environmental and health risks. Investigations into pure, binary, and ternary mixtures of BP3, NaCl, and the photosensitizer 4-benzoyl benzoic acid using solar-simulated light isolated the effects of salt and photosensitization on BP3 degradation.

The first-ever measurements of SMA by extractive electrospray ionization mass spectrometry highlighted the importance of hydrocarbons such as isoprene and monoterpenes in producing organic aerosol mass, demonstrating how the organic character of SMA shifts throughout a phytoplankton bloom, and identified the role of phytoplankton and bacterial production sources of sulfur- and nitrogen-containing substituents.

This dissertation emphasizes the intricate interactions between pollutants, natural marine processes, and atmospheric dynamics. It contributes to a deeper understanding of the complex interplay between coastal contaminants and marine atmospheric chemistry, highlighting the urgent need for comprehensive environmental management strategies.