Application of a hybrid chemical transport-receptor model to develop region-specific source profiles for PM2.5 sources and to assess source impact changes in the United States

Abstract

A novel, hybrid chemical transport/receptor model approach is used to develop spatial fields of daily source impacts. The spatial-hybrid (SH) method uses source impact fields obtained from CMAQ simulations, which are then adjusted to better match species-specific observations. Specifically, the SH method assimilates modeled 36-km source impact estimates from CMAQ and ground observations from the Chemical Speciation Network (CSN) to produce source impacts that better reflect observed data. New source profiles are generated using source impact results from the SH method. The new source profiles reflect modeled and observed concentrations and also reflect secondary formation processes that are captured by CMAQ. Results of the application of this method suggest that the default source profiles used in emissions inventories may be inconsistent with observations. In this work, we present SH source impact fields over the year 2006. These results are then used to develop updated source profiles for fine particulate matter sources for the contiguous U.S. The profiles characterize the composition of 22 particulate matter species, including major ions, carbon species, and 17 metals. Sources analyzed include fossil fuel combustion, mobile sources, sea salt, biogenic emissions, biomass burning, as well as livestock operations, agricultural activities, metals processing, and solvents. Source profiles are evaluated by comparing results for two locations Atlanta, GA, and St. Louis, MO to previous studies.