Atmospheric Chemistry Program Seminar: Jonathan Slade, UCSD

Into the mist: Exploring the physicochemical properties of marine aerosols and their impacts on the fate of plastic additives in the atmosphere

Prof. Jonathan Slade, 
Assistant Professor of Chemistry
Department of Chemistry & Biochemistry
University of California, San Diego
 

Aerosols—tiny particles suspended in the air—play a critical role in global climate and human health. Sea spray aerosols (SSA), generated by breaking ocean waves, are the largest source of aerosol mass in the atmosphere, with oceans covering over 70% of the Earth’s surface. Increasingly, plastics (micro- and nano-plastic particles), plastic chemical residues (e.g., bisphenols), and personal care products (e.g., sunscreens, detergents) are emerging as concerns in marine environments. These substances are highly resistant to both photodegradation and biodegradation in surface water, allowing them to persist in seawater for weeks to months. Their accumulation at the air-sea interface is particularly concerning as they can transfer into SSA. These aerosols can be inhaled, deposited on surfaces, or transported long distances, exposing areas far from the coast. However, the extent of this transfer, the transformations these substances undergo, and their atmospheric lifetimes due to aging in SSA remain poorly understood.

In this talk, I will present our efforts to explore the composition and physicochemical properties (i.e., viscosity and hygroscopicity) of SSA and the fate of plastic chemical residues in them. Viscosity, a key property influencing aerosol multiphase chemistry and kinetics, has been largely overlooked in studies of SSA. This includes (1) investigating the viscosity of SSA and the unique chemical interactions, including cation-mediated gel formation, influencing it along a pristine sea surface in a controlled wave flume, (2) quantifying organic pollutants and plastic residues in aerosols collected near a contaminated coastal water source, and (3) examining the multiphase and photo-initiated oxidation kinetics driving the degradation of plastic and personal care product components in SSA mimics in the lab. Ultimately, our goal is to understand the interplay between aerosol pollutant emissions and aerosol properties impacting the fate of these emissions, as pollution in coastal environments is expected to increase.