Application of EPA CMB8.2 model for source apportionment of PM(2.5) in Corpus Christi, Texas.

摘要

Corpus Christi, located in South Texas along the Gulf of Mexico, is a fast growing urban region in Texas and it is considered to be a near non-attainment area for ozone. Continuous Ambient Monitoring Stations (CAMS) maintained by Texas Commission on Environmental Quality (TCEQ) measures various pollutants and meteorological parameters. The study region is currently in compliance with the National Ambient Air Quality Standards (NAAQS) for PM2.5. However, an increasing trend was observed in the PM levels since 2003 and the study region was found to be impacted by both regional and local sources during episodes of high PM.; Filter samples were collected once in six days by TCEQ at CAMS635 (an urban site) starting in 2001 and at CAMS314 (a coastal site) since 2003. The filters were sent to Research Triangle Institute, North Carolina for gravimetric and chemical analysis. Speciation data from the two monitoring sites was obtained for the study period of 2003--2005 from TCEQ for this study. Twenty five key chemical species (ionic and elemental species) in PM were considered for a compositional analysis and source apportionment. Chemical Mass Balance (CMB8.2), a receptor model developed by the United States Environmental Protection Agency (U.S EPA), was used for the source apportionment analysis. The sample dataset consisted of two hundred and twenty samples. Thirteen source profiles were chosen from EPA's SPECIATE library to better characterize the composition and distribution of fine particulate matter in the urban airshed.; The results from the analysis highlighted key species and major contributing source types affecting the urban site (CAMS635) and the coastal site (CAMS314). These included secondary sulfates, secondary organic aerosols, light duty vehicles, heavy duty vehicles, marine aerosol, petroleum industry, residential wood combustion and field burning. The dominant source types that were common in both the urban and coastal sites included sources of secondary sulfates (42% at the urban and 37% at the coastal) and sources of secondary organic aerosols (20% and 13%, respectively). Additional sources that had minor impacts included paved and unpaved road dust, food and agricultural activities and crustal material. The contribution of marine aerosols was observed to be higher at CAMS314 than CAMS635 as CAMS314 is located closer to the coast.