Regulatory Application of Microscopic Techniques to Understand Particle Morphology and Composition

CYNTHIA BERG, Cat Buhl, Angela Haar, Joshua Scheel, Hedy Ward, Selina Ibarra, South Coast Air Quality Management District

     Abstract Number: 560
     Working Group: Instrumentation and Methods

Abstract
The South Coast Air Quality Management District (South Coast AQMD) is the government agency responsible for monitoring and regulating stationary sources of air pollution in the South Coast Air Basin and Coachella Valley (a portion of the Salton Sea Air Basin) in Southern California. The agency uses polarized light microscopy (PLM), Fourier-Transform Infrared Spectroscopy (FTIR), and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) to analyze particulate matter and understand the morphology and composition of particles to aid in the identification and attribution of sources. These instruments have been used to examine unknown particulate matter in response to community concerns and to identify possible emission sources for further investigation. Here we describe how these instruments and techniques are used to support agency efforts to enforce regulations and better understand sources of particulate matter in the basin. A long-term study of the composition of particulate matter fallout and source attribution in the Eastern Coachella Valley (January 2022 – December 2022) will also be presented. During this study fallout samples were collected and analyzed by SEM-EDS as part of efforts to distinguish the source of particulate matter, attributing it to local to agricultural operations or resuspended particulates from the Salton Sea playa.