AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Source Apportionment of Carbonaceous Ultrafine Particulate Matter (PM0.1) in Four Polluted Cities in California
JIAN XUE, Wei Xue, Michael Kleeman, University of California, Davis
Abstract Number: 582 Working Group: Source Apportionment
Abstract Recent epidemiological studies suggest that Ultrafine particles (PM0.1) is associated with a range of public health impacts including premature mortality. The potential public health burden of PM0.1 can only be understood by monitoring ambient concentrations. In this study, a sampling network was deployed across four polluted California cities for one year (2015/2016) to measure the concentration and composition of PM0.1 to support an exposure assessment and source apportionment study. Two measurement sites were located in the San Francisco Bay Area (East Oakland and San Pablo), one site was located in Fresno, and one site was located in Los Angeles. PM0.1 samples were analyzed for trace metals, EC/OC fractions, and molecular markers. A chemical mass balance (CMB) receptor model using molecular markers was then applied to quantify PM0.1 contributions in major California cities.
The PM0.1 carbonaceous concentration were highest in the largest cities, in the order of LA>East Oakland>San Pablo>Fresno, reflecting the effects of regional anthropogenic emissions. Winter concentrations were higher than summer concentrations by a factor of approximately 1.5-2. The major primary sources that contribute PM0.1 OC in California cities include meat cooking (22-38%), biomass burning (8-30%), diesel exhaust (14-20%) and gasoline exhaust (8-18%). Wood burning (30%) and mobile exhaust (diesel+gasoline) (36%) were identified as the most important sources for PM0.1 OC at the Fresno and LA sites, respectively. These locations also had a much higher fraction of unidentified source contributions (22-25% vs. 2-5% at the SF Bay Area sites), suggesting more important contribution from the secondary organic aerosol (SOA). Distinct seasonal variation was observed with wood burning, accounting for 30-60% of PM0.1 OC in winter (negligible contribution in summer) and SOA accounting for 20-70% of PM0.1 OC in summer (negligible contribution in winter). Diesel exhaust accounted for 60-80% of PM0.1 EC, with the rest mainly contributed by gasoline exhaust. These results will support the evaluation of future model calculations for PM0.1 exposure conducted across California for 2015/16.