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Qualitative and quantitative assessment of Unresolved Complex Mixture in PM2.5 of Bakersfield, CA.
Citation:
Nallathamby, P., M. Lewandowski, M. Jaoui, J. Offenberg, Tad Kleindienst, C. Rubitschun, J. Surratt, S. Usenko, AND R. Sheesley. Qualitative and quantitative assessment of Unresolved Complex Mixture in PM2.5 of Bakersfield, CA. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 98(2014):368-375, (2014).
Impact/Purpose:
The National Exposure Research Laboratory’s (NERL’s) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA’s mission to protect human health and the environment. HEASD’s research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA’s strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.
Description:
The 2010 CalNex (California Nexus) field experiment offered an opportunity for detailed characterization of atmospheric particulate carbon composition and sources in Bakersfield, CA. In the current study, the authors describe and employ a new protocol for reporting unresolved complex mixture (UCM) in over 30 daily samples. The Bakersfield, CA site has significant contribution from UCM, up to 9% of the daily OC, which makes it an ideal first application. The new protocol reports two UCM peaks for Bakersfield with unique mean vapor pressure, retention time, mass spectra and daily ambient concentration trends. The first UCM peak, UCM-A, was comprised of semi-volatile compounds including alkanes, alkenes, and alkynes, with a mean vapor pressure of 2E-04 Torr and medium to heavy-duty diesel exhaust as a likely source. The second UCM peak, UCM-B, was comprised of linear, branched, and cyclic alkanes, with a mean vapor pressure of 1E-08 Torr. UCM-B had strong similarities to UCM in the NIST Standard Reference Material 1649b (urban dust) and to previously reported detailed UCM for a representative Bakersfield sample (2013), with possible sources including: motor vehicle exhaust and fugitive dust from roads in urban and rural areas, agricultural activities, and construction activities.
URLs/Downloads:
FINAL FINAL ACCEPTED_MANUSCRIPT.PDF (PDF, NA pp, 911.186 KB, about PDF)Atmospheric Environment
