Morphology and Hygroscopicity of Nanoplastics in Sea Spray Determined by Humidified Tandem Differential Mobility Analysis Coupled to High-Resolution Time-of-Flight Aerosol Mass Spectrometry

SARAH PETTERS, Eva Kjærgaard, Freja Hasager, Andreas Massling, Marianne Glasius, Merete Bilde, Aarhus University

     Abstract Number: 619
     Working Group: Aerosol Sources and Constituents of Emerging Importance and Their Impacts across Spatial Scales

Abstract
The environmental detection, fate, and transport of micro- and nanoplastics is becoming a topic of great interest in environmental chemistry, atmospheric chemistry, and public health. The presence of microplastics (diameter < 5 mm) in living tissue suggests a strong potential for numerous adverse health effects. Plastic particles accumulate in the ocean and recent works suggest that they can be transferred to the air with sea spray through wave-breaking action. The role of airborne nanoparticles (diameter < 1000 nm) in atmospheric chemistry and public health is largely controlled by particle size, morphology, and surface composition and coatings. Size-resolved aerosol mass spectrometry provides real-time characterization of submicron atmospheric particles. However, the analysis of nanoplastics in complex aerosol mixtures such as sea spray is severely limited by challenges associated with the detection limit of the instrument as well as the high background signal of the aerosol matrix. In this work we characterize the internal and external mixing state of sea spray aerosols spiked with nanoplastics. A humidified tandem differential mobility analyzer is used as a size and hygroscopicity filter, separating the nanoplastics from the sea spray, and an inline high-resolution time-of-flight aerosol mass spectrometer is used to characterize particle composition and internal mixing state. Aerosol from both synthetic and near-shore samples was internally and externally mixed. Aerosol enrichment and coating have a profound impact on aerosol hygroscopic water uptake and humidified size distributions, impacting aerosol efficiency in nucleating cloud drops and the oxidative aging of the particles. This work broadly contributes to the growing understanding of the detection, morphology, and hygroscopicity of micro- and nanoplastics in the lower atmosphere and their impact on the environment and the earth system.