Realizing additional benefits of federal air quality rules: particle water chemistry and biogenic secondary organic aerosol controllable fractions

Seminar | April 3 | 4-5 p.m. | 120 Latimer Hall

 Ann Marie Carlton, Department of Chemistry, UC Irvine

 College of Chemistry

Accurate description of the factors that control pollution fate and transport by atmospheric models aids effective air quality management. For example, models can safeguard human health from the deleterious effects of fine particulate matter (PM2.5) though analysis of optimal control strategies for precursor gases. Anthropogenic emissions facilitate formation of biogenic secondary organic aerosol (SOA) and add to atmospheric PM2.5. Previous experiments with EPA’s Community Multiscale Air Quality (CMAQ) model suggested anthropogenic primary organic aerosol (POA) emissions impact biogenic SOA to the largest extent. Those experiments included biogenic SOA formation processes from vapor pressure dependent semi-volatile partitioning, but not recently discovered condensed-phase chemistry involving aerosol liquid water (ALW). We conduct new CMAQ simulations with ALW-influenced chemistry and evaluate changes in predicted biogenic SOA, usually enhancement, due to individual pollutants and individual sources. The CMAQ simulations suggest SO2 emissions from electricity generating units (EGUs) and mobile sources of NOx emissions impact biogenic SOA to the greatest degree. Removal of controllable emissions of NOx, SO2 and POA from CMAQ inputs reduces nationally averaged biogenic SOA by 23%, 14% and 8%, respectively. Predicted ALW mass concentration response to anthropogenic emissions from specific source sectors is quantitatively evaluated for the first time with CMAQ and found to decrease by 10% and 35% in response to removal of controllable NOX and SO2 emissions, respectively. This work suggests ancillary benefits of existing and planned Federal NOX and SO2 air quality rules through simultaneous organic PM2.5 mass reductions.

 Light refreshments will be served at 3:50 at The Coffee Lab, 510-643-0572