tailieunhanh - Source Identification of Volatile Organic Compounds in Houston, Texas

The complexity of the volatile organic compound (VOC) mixture in the Houston area makes studies of the air quality in that area very challenging. In this paper, a novel factor analysis model, where the normal chemical mass balance model was augmented by a parallel equation that accounted for wind speed and direction, temperature, and weekend/weekday effects, was fitted with a multilinear engine (ME) to provide identification and apportionment of the VOC sources at the La Porte Municipal Airport site in Houston during the Texas Air Quality Study (TexAQS) 2000. The analysis determined the profiles and contributions of nine sources and the corresponding wind speed, wind direction, temperature, and weekend factors. The reasonableness of. | Environ. Sci. Technol. 2004 38 1338-1347 Source Identification of Volatile Organic Compounds in Houston Texas WEIXIANG ZHAO PHILIP K. HOPKE t AND THOMAS KARL Department of Chemical Engineering Clarkson University Box 5708 Potsdam New York 13699-5708 and The National Center for Atmospheric Research Atmospheric Chemistry Division . Box 3000 Boulder Colorado 80307 The complexity of the volatile organic compound VOC mixture in the Houston area makes studies of the air quality in that area very challenging. In this paper a novel factor analysis model where the normal chemical mass balance model was augmented by a parallel equation that accounted for wind speed and direction temperature and weekend weekday effects was fitted with a multilinear engine ME to provide identification and apportionment of the VOC sources at the La Porte Municipal Airport site in Houston during the Texas Air Quality Study TexAQS 2000. The analysis determined the profiles and contributions of nine sources and the corresponding wind speed wind direction temperature and weekend factors. The reasonableness of these results not only suggests the high resolving power of the expanded factor analysis model for source apportionment but also provides the novel and effective auxiliary information for more specific source identification. In addition a new approach to estimate the measurement uncertainty and the details of determining the source number and dealing with missing values are also presented as important parts of the data analysis process. This study demonstrates the feasibility of the expanded model to identify sources in complex VOC systems and extract useful information for locating VOC emitters and controlling their emissions in the Houston area. Introduction Volatile organic compounds VOC are organic chemicals that easily vaporize at room temperature. Many VOCs have been found to have adverse effects on air quality and human health 1 . For example long time exposure to benzene will .