(637c) Environmentally Relevant Polystyrene Micro- and Nano- Plastics (MPs and NPs) Accumulation and Their Interaction with Lipids at Air-Sea Water (SW) Interface

Despite increasing efforts to recycle plastic materials waste continue to accumulate in the oceans and it has been shown to accumulate in and negatively impact the health of marine life and added stress on ecosystems. Sea surface microlayers (SSMLs) is one of the critical natural components of oceans and a point of initial exposure to plastic pollution. SSML ranges from 1 to 1000 micrometer thick, are ubiquitous globally and are comprised of natural molecules, heavy metals, lipids, proteins, microorganisms, and particulate pollutants including microplastics (MPs) and nanoplastics (NPs). Persistent mechanical and photo-chemical degradation of plastics in the ocean yields micro- and nanoscale plastics (MPs and NPs) particles, which have been attracted much attention for their considerable hazards. It is equally important in determining how MPs and NPs are transformed within the SSMLs as transformations govern fate and transport. Detailed fundamental understanding of the SSMLs and impact of surface-active and particulate pollutants, are still lacking. In this study, we applied an accelerated weathering protocol to consumer plastics (Polystyrene (PS)) to create the engineered MPs and NPs using top-down method and investigated their colloidal properties in respect to their size, morphology, stability, and chemical composition under defined conditions. Engineered MPs and NPs have different average size fractions ranging from 5-10 μm, 1-5 μm, and < 1 μm with significant size and shape heterogeneity. We demonstrated the labeling approach of MPs with fluorescence dye (Nile Red) to facilitate the visualization and/or detection of MPs at the SSMLs. We also report their surface activity as well as their interaction with model lipid palmitic acid (PA) (abundant lipids in SSML) at the interface using Langmuir monolayer study. The intrinsic behavior of the MPs and NPs driving the surface activity and compressibility of the complexes at the air-lipid-SW interface. Our results provide physical and molecular characterization of a potentially significant MPs and NPs enrichment mechanism within the lipid monolayer at air-sea water interfaces.