Characterization of Ambient Metal Particles in Real Time Using Atomic Emission Spectroscopy: Urban and Rural Environments
Hanyang Li, Leonardo Mazzei, Christopher Wallis, ANTHONY S. WEXLER,
University of California, Davis Abstract Number: 19
Working Group: Instrumentation and Methods
AbstractExposure to toxic metal particles is known or suspected to affect human health. In order to help underrepresented communities determine the source of toxic metals and evaluate future actions that may reduce emissions in their neighborhoods, we recently developed a toxic-metal aerosol real-time analyzer (TARTA). TARTA is relatively inexpensive (~ $3,000), compact (1 ft cube), high time resolution (30 minutes), and power-efficient (< 30 W).
In this study, TARTA is used to measure metal emissions of PM2.5 from different ambient environments, including the emissions of vehicles traveling through the Caldecott tunnel, the urban emissions near downtown Sacramento, and the agricultural emissions from a rural background site in Davis. In parallel, we collected particle samples on Teflon filters for X-ray fluorescence (XRF) analysis of trace metals and at the Sacramento site monitored the elemental composition using the Cooper Environmental’s Xact 625 Ambient Metals Monitor. The analytical results obtained by in situ Xact and offline XRF analysis allow for the evaluation of the accuracy and sensitivity of TARTA.
We also identified the major sources of metal particles in each region using the positive matrix factorization (PMF) model. For the tunnel environment, the best association exists between Fe, Cr, Mn, Cu, and Zn (0.61 < R < 0.96), suggesting that they are from similar pollution sources (e.g., the exhaust emission from vehicle engines and automotive brake and tire wear). On the other hand, the rural site shows the best correlation among crustal elements (including Na, Mg, Ca, and K with R > 0.8), which are blown by wind and resuspended by cattle and tractor operations near the sampling site.