Origins of fine aerosol mass in the Baltimore–Washington corridor: implications from observation, factor analysis, and ensemble air parcel back trajectories
2002; Elsevier BV; Volume: 36; Issue: 28 Linguagem: Inglês
10.1016/s1352-2310(02)00399-0
ISSN1873-2844
AutoresL.‐W. Antony Chen, Bruce G. Doddridge, Russell R. Dickerson, Judith C. Chow, Ronald C. Henry,
Tópico(s)Air Quality Monitoring and Forecasting
ResumoChemically speciated fine particulate matter (PM2.5) and trace gases (including NH3, HNO3, CO, SO2, NOy) have been sampled at Fort Meade (FME: 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. Measurements over a 2-year period include eight seasonally representative months. The PM2.5 shows an annual mean of 13 μg m−3 and primarily consists of sulfate, nitrate, ammonium, and carbonaceous material. Day-to-day and seasonal variations in the PM2.5 chemical composition reflect changes of contribution from various sources. UNMIX, an innovative receptor model, is used to retrieve potential sources of the PM2.5. A six-factor model, including regional sulfate, local sulfate, wood smoke, copper/iron processing industry, mobile, and secondary nitrate, is constructed and compared with reported source emission profiles. The six factors are studied further using an ensemble back trajectory method to identify possible source locations. Sources of local sulfate, mobile, and secondary nitrate are more localized around the receptor than those of other factors. Regional sulfate and wood smoke are more regional and associated with westerly and southerly transport, respectively. This study suggests that the local contribution to PM2.5 mass can vary from 60% in winter.
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