AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Lead Impacts from General Aviation Airports: A Weight of Evidence Approach
STEPHEN FEINBERG, Jay Turner, Washington University in St. Louis
Abstract Number: 331 Working Group: Urban Aerosols
Abstract In 2008 the USEPA revised the National Ambient Air Quality Standard for lead (Pb). The more stringent standard has drawn attention to the need for refined emissions estimates and approaches to identify Pb concentration hot spots. Nationwide, piston engine aircraft are the single largest emission source of airborne Pb with emissions concentrated at general aviation (GA) airports. This study was performed to refine the Pb emission inventory methodology for piston engine aircraft activities at GA airports. Three one-month field campaigns were conducted at GA airports in Tulsa, OK, Denver, CO and Santa Monica, CA to collect airborne Pb data for model-to-monitor reconciliation. Measured Pb concentrations were compared to modeled airport impacts by performing dispersion modeling with the refined emissions inventory. This presentation focuses on analysis of the ambient particulate Pb measurements. PM$_(2.5) and total suspended particulate (TSP) samples were collected at multiple locations at each airport and analyzed for lead content by both inductively coupled plasma – mass spectrometry (ICP-MS) and X-ray fluorescence (XRF). Contributions from the combustion of Pb-bearing aviation gasoline (avgas) were assessed using Pb/Bromine (Br) ratios and Pb isotopic composition. Pb and Br were highly correlated in samples predicted to have high impacts from avgas combustion. However, the Pb/Br ratios were lower than expected from either lead bromide or lead bromochloride. Soil and avgas samples were also analyzed for isotopic composition. Ambient samples collected at high impact sites had isotope ratios consistent with avgas while samples collected at low impact sites had ratios similar to soil or trending toward avgas. Isotope analysis of TSP samples from high impact sites were more similar to avgas than soil and did not trend towards the soil ratios with increasing coarse fraction Pb.