Source apportionment of fine aerosol mass and chemical composition in the Baltimore-Washington corridor

PM2.5 and Electric Power Generation:Recent Findings and Implications?

L.-W. Antony Chen ; Bruce G. Doddridge ; Russell R. Dickerson

Others  :  http://www.netl.doe.gov/publications/proceedings/02/PM25/2.2.2Chen_s.pdf
PID  :  24888

来源: CEUR

【 摘 要 】

As the primary field experiment for the Maryland Aerosol Research and CHaracterization (MARCH-Atlantic) study, chemically speciated PM2.5 and trace gases (NH3, HNO3, CO, SO2, NOy, etc) have been sampled at Fort Meade (39.10°N, 76.74°W; elevation 46 m MSL), Maryland, since July 1999. FME is suburban, located in the middle of the Baltimore-Washington corridor, and generally downwind of the highly industrialized Midwest. The PM2.5 at FME is expected to be of both local and regional sources. The goal of this study is to investigate the origins of PM2.5 mass based on the daily/seasonal variation of PM2.5 chemical compositions. 24-hr average PM2.5 data acquired over a 2-year period, including 8 seasonrepresentative months, are presented here. Major mass contributing species in PM2.5 includes sulfate, nitrate, ammonium, and carbonaceous material. Ammonium sulfate dominates in summer (> 50%) but its fraction decreases to ~ 30% in winter when more ammonium nitrate is formed due to lower temperatures. Carbonaceous material, including elemental carbon (EC) and organic carbon (OC), accounts for 25 – 35% of the PM2.5 mass. Good correlations are observed between EC, CO, and NOy, EC and a large fraction of OC likely result from mobile emissions in the B-W corridor. Crustal material (Al, Si, Ca, Fe, K, etc) and sea salt (Na+ and Cl-) aerosols are minor, contributing to < 5% of the PM2.5 mass. Reconstructed PM2.5 mass is calculated, and it generally agrees with the gravimetric mass except a deficit probably resulting from the unaccounted H2O. [First Paragraph]