Evaluation of organic markers for chemical mass balance source apportionment at the Fresno Supersite J. C. Chow1, J. G. Watson1, D. H. Lowenthal1, L. W. A. Chen1, B. Zielinska1, L. R. Mazzoleni2, and K. L. Magliano3 1Desert Research Institute, Reno, NV, USA 2Colorado State University, Fort Collins, CO, USA 3California Air Resources Board, Sacramento, CA, USA
Abstract. Sources of PM2.5 at the Fresno Supersite during high PM2.5
episodes occurring from 15 December 2000–3 February 2001 were estimated
with the Chemical Mass Balance (CMB) receptor model. The ability of source
profiles with organic markers to distinguish motor vehicle, residential wood
combustion (RWC), and cooking emissions was evaluated with simulated data.
Organics improved the distinction between gasoline and diesel vehicle
emissions and allowed a more precise estimate of the cooking source
contribution. Sensitivity tests using average ambient concentrations showed
that the gasoline vehicle contribution was not resolved without organics.
Organics were not required to estimate hardwood contributions. The most
important RWC marker was the water-soluble potassium ion. The estimated
cooking contribution did not depend on cholesterol because its
concentrations were below the detection limit in most samples. Winter time
source contributions were estimated by applying the CMB model to individual
and average sample concentrations. RWC was the largest source,
contributing 29–31% of measured PM2.5. Hardwood and softwood
combustion accounted for 16–17% and 12–15%, respectively. Secondary
ammonium nitrate and motor vehicle emissions accounted for 31–33% and
9–15%, respectively. The gasoline vehicle contribution (3–10%) was
comparable to the diesel vehicle contribution (5–6%). The cooking
contribution was 5–19% of PM2.5. Fresno source apportionment results
were consistent with those estimated in previous studies.
Citation: Chow, J. C., Watson, J. G., Lowenthal, D. H., Chen, L. W. A., Zielinska, B., Mazzoleni, L. R., and Magliano, K. L.: Evaluation of organic markers for chemical mass balance source apportionment at the Fresno Supersite, Atmos. Chem. Phys., 7, 1741-1754, doi:10.5194/acp-7-1741-2007, 2007.