Abstract View
Consideration of Dynamic Gas-Particle Partitioning in National-Scale Emission Inventories
BENJAMIN MURPHY, Aditya Sinha, Quanyang Lu, Claudia Toro, Amara Holder, Ying Hsu, Madeleine Strum, Hugo Denier van der Gon, Justine Geidosch, Ingrid George, Andrew Grieshop, Michael Hays, Darrell Sonntag, George Pouliot, Havala Pye, David Simpson, Allen Robinson, United States Environmental Protection Agency
Abstract Number: 146
Working Group: Instrumentation and Methods
Abstract
Conventional particle emission measurement and inventory methods (i.e. the EPA National Emission Inventory) characterize total particle mass and composition as the mass of material collected on a filter (e.g. Teflon, glass fiber or quartz) or with an online technique (e.g. aerosol mass spectrometer) during typical operation. Standard protocols for measuring PM emission factors exist for important sources like wood combustion, vehicle exhaust, or energy generation, and some of these protocols account for ambient processes such as particle enhancement from vapor condensation during cooling. However, this accounting is variable across source categories and among countries. For condensable organic matter, additional shifts in gas-particle partitioning are possible as plumes dilute to ambient concentrations and temperatures. Chemical transport model studies have clearly demonstrated the importance of these processes when predicting ambient particle concentrations, both in the U.S. and elsewhere.
Our goal is to improve existing EPA emissions estimation techniques with up-to-date knowledge of organic aerosol volatility. We demonstrate methods for applying speciation profiles to PM emission factors that distribute the organic emissions into lumped groups consistent with the Volatility Basis Set framework and consider complications from several issues including potential missing semivolatile organic compounds. We also discuss potential inconsistencies between speciation profile datasets and emission factor databases and make the case for greater harmonization and detailed emissions reporting, particularly for sources with high organic contribution. We focus on efforts involving engine-exhaust sources with profiles now available in the SPECIATEv5.0 database (https://www.epa.gov/air-emissions-modeling/speciate) and profiles recently developed for open and controlled combustion of biomass measured in lab and field studies. These efforts involve offline measurements that can be readily applied to other sources and source classes as well.