Ambient Particulate Metals and Their Sources at the Los Angeles ASCENT Site
HAROULA D. BALIAKA, Ryan X. Ward, Sina Hasheminassab, Paul Wennberg, Roya Bahreini, Ann M. Dillner, Armistead G. Russell, Nga Lee Ng, Richard Flagan, John Seinfeld, California Institute of Technology
Abstract Number: 500
Working Group: Coast to Coast Campaigns on Aerosols, Clouds, Chemistry, and Air Quality
Abstract
The Los Angeles basin is one of the most polluted airsheds in the United States. The region’s dense urban landscape and its topography promote the accumulation of anthropogenic and biogenic emissions, and, despite regulatory efforts, poor air quality persists. Ambient metals comprise about 5% of total particulates (PM2.5) and are an important category of hazardous air pollutants with known detrimental impacts on human health. With direct tailpipe emissions from vehicles in California improving, attention has shifted towards brake and tire wear particulate matter as one of the dominating sources of traffic-related emissions. In this work, we conduct field measurements at an urban site in Pico Rivera, in Los Angeles County, CA that is in close proximity to a dense cluster of metal processing facilities located in East/Southeast LA. This site is part of the Atmospheric Science and Chemistry mEasurement NeTwork (ASCENT) and is equipped with a suite of advanced aerosol instrumentation for real-time measurements of fine aerosol chemical composition and properties. An Aerosol Chemical Speciation Monitor (ACSM) measures the composition and mass concentration of the non-refractory aerosols, an Xact monitors trace elements, an Aethalometer measures black and brown carbon, and a Scanning Mobility Particle Sizer (SMPS) is used for the aerosol number size distribution. Here, we present results on the temporal (i.e., diurnal, day-of-the-week, seasonal) trends in the measured PM2.5-bound metals derived from the Xact instrument. We compare with other studies measuring total suspended particulate metals and explore the effect of coarser vs fine particles. Lastly, we perform Positive Matrix Factorization (EPA v 5.0) source apportionment analysis on the ACSM and multi-metals data as well as complimentary measurements and identify major sources associated with road dust, industrial emissions, and brake wear.