Characterization of Microplastics in the Atmosphere in the Eastern United States

ALEXIS SMITH, Heather Neel, Danielle Haller, Marwa El-Sayed, Foram Madiyar, Embry-Riddle Aeronautical University

     Abstract Number: 639
     Working Group: Urban Aerosols

Abstract
Microplastics (MPs) are defined as small fragments of plastic that are less than 5mm in size. Previous research has primarily focused on MPs in the marine environment; however, characterization of MPs in the atmosphere is yet limited. The goal of this study is to characterize the concentration and composition of MPs in the atmosphere.  Filter-based ambient sampling of MPs is routinely conducted to provide insight into their concentrations and deposition rates. However, other atmospheric particles are also collected onto these filters during sampling. To eliminate these particles from the samples, previous studies used chemical solutions as a pretreatment step prior to MPs characterization. However, to the best of our knowledge, no study has investigated the conditions at which this pre-treatment step should be conducted without altering the shape and size of the collected MPs . Herein, a sample pre-treatment methodology was investigated for two widely used MPs, namely Polystyrene (PS) and Poly(methyl methacrylate) using multiple concentrations of nitric acid (acid), potassium hydroxide (base), and hydrogen peroxide (oxidizing agent) at various temperatures. Preliminary results show that for PS, such conditions occur at 15% H2O2 at room temperature. To validate our method, optimum pre-treatment conditions are tested on ambient samples collected at Embry-Riddle Aeronautical University campus in Daytona Beach, Florida. Active and passive sampling is conducted using the Tisch High Volume Air Sampler, and a setup devised to hold the glass filter, respectively. Optical and chemical characterization of MPs is conducted using a ZEISS Axioscope 7 compound microscope to determine their size distribution and a Fourier transform infrared (FTIR) spectroscopy to investigate their chemical properties, respectively. This study has implications for the effects of MPs on human health via inhalation, as well as their effects on water bodies and soil upon deposition.