Trace and Major Elements in Aerosol in Urban Southeastern Pennsylvania, US: Combining SP-AMS Mobile Monitoring with Fixed Site Size-Resolved Measurements by ICP-MS

The Chester-Trainer-Marcus Hook, PA area is home to a refinery, waste incinerator, and petrochemical plants, some abutting residential communities. US EPA analyses indicate that trace metals from industrial emissions pose health risks in this region. Existing information on fenceline community exposures is based on monitoring data with low temporal and spatial resolution and EPA models that rely on industry self-reporting. This study aimed to 1) compare current size-resolved metals concentrations in particulate matter (PM) in the Chester-Trainer-Marcus Hook area with existing reports, and 2) explore source identification using stationary integrated sampling and mobile measurements. Size-resolved PM (0.056-18 μm) was collected at a Chester fixed site during a 3-week campaign in September 2021 and analyzed by Inductively-Coupled Plasma Mass Spectrometry (ICP-MS). Spatially resolved on-line aerosol measurements were conducted by Soot-Particle Aerosol Mass Spectrometry (SP-AMS) using the Aerodyne Inc. mobile laboratory.

EPA-modeled metals concentrations in total PM were lower (p<0.001) than fixed-site measurements for arsenic, lead, antimony, cobalt and manganese in this study. Heavy metals arsenic, lead and cadmium were predominantly observed in submicron PM, the fraction which can penetrate deeply into the lungs. ICP-MS and fixed site-adjacent SP-AMS measurements for lead, aluminum, potassium and selenium were moderately associated (R2 > 0.3). Positive Matrix Factorization analysis of fixed site ICP-MS data suggested the presence of four main sources (sea salt, mineral dust, combustion, and non-exhaust vehicle emissions). Mobile monitoring data were consistent with the latter three sources. SP-AMS measurements showed elevated levels of five combustion-related elements (cadmium, chromium, nickel, copper, and potassium) near a refinery complex. Antimony, a brake wear tracer, exhibited hotspots near intersections by mobile monitoring. These results suggest potential co-exposures to atmospheric metal/metalloids at levels that may exceed previous estimates from EPA modeling in communities surrounding the Chester-Trainer-Marcus Hook industrial area. Further work is needed to characterize the cumulative health risk of these inhalation exposures.