AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
A Hybrid Source-receptor Modeling Approach for Estimating Source Contributions to Trace Metals in Airborne Particulate Matter
QI YING, Jianlin Hu, Hongliang Zhang, Texas A&M University
Abstract Number: 471 Working Group: Source Apportionment
Abstract Estimating of regional concentrations of trace metals using a chemical transport model (CTM) is challenging in that speciation profiles needed to estimate their emissions are often unavailable or have significant uncertainties due to very limited source testing data. A hybrid source-receptor modeling approach is developed to calculate regional distribution of trace metals utilizing predicted regional source contributions to primary PM (PPM) mass concentrations from a source-oriented CTM and the nominal emission factors of the trace metals (g/g of PPM emitted) derived from a multilinear regression analysis. For a trace metal species with measured concentrations on multiple days, the multilinear regression analysis uses predicted source contributions to PPM to estimate the optimal emission factors of the trace metal for each source so that root mean square of the difference between the predicted and observed trace metal concentrations were minimized.
In this study, regional distributions of 13 trace metals (Al, As, Ba, Ca, Cr, Cu, K, Mn, Na, Pb, Si, Ti, Zn) as well as elemental carbon (EC) concentrations in airborne particulate matter (PM) in China and the contributions of six major sources (windblown dust, residential sources, transportation, power generation, industries and open burning) to these elements were estimated using the hybrid approach. Observed concentrations of trace metals on campus of the Beihang University, which is located at an urban location in Beijing, along with the predicted PPM concentrations at that location were used to derive the emission factors. The ability of the hybrid method in predicting trace metal concentrations was evaluated by comparing the predicted and observed concentrations of trace metals in Nanjing, a major city in the Yangtze River Delta that is about 1000 km south of Beijing, and in Chengdu, a major city in Western China.