Houston, Texas - Urban air quality studies

Urban zones represent areas in which significant amounts of gaseous pollutants and particulate matter are released into the atmosphere. The Houston-Galveston Brazoria Area (HGB), located close to the Gulf of Mexico, is the fourth largest metropolitan area in the United States. 
The University of Houston (UH) set up an air quality measurement facility at the University main campus on the roof of the 18-story tall North Moody Tower residence hall. The general information about this site is given in Table 1. This facility includes a 35 ft high sampling tower and is equipped with air chemistry measurements including O3, CO, NO, NO2, NO, PAN, PPN, MPAN, VOCs, and meteorological instrumentation. It also includes measurements of photolysis frequencies for O3, NO, HONO and HCHO and 16 other important photolysis reactions.
Aero-Laser equipment is used for the TexAQS II Radical Measurement Project (TRAMP) in 2006 and several other research programs.

Moody Progress Report

Further informations

Publications

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Article

Title: Deciphering the Role of Radical Precursors during the Second Texas Air Quality Study
Authors: E.P. Olaguer, B. Rappenglück, B. Lefer, J. Stutz, J. Dibb, R. Griffin, W.H. Brune, M. Shauck, M. Buhr, H. Jeffries, W. Vizuete and J.P. Pinto
Journal: J. Air Waste. Manage. Assoc.
Year: 2009
Volume: 59
Pages: 1258
DOI: 10.3155/1047-3289.59.11.1258
Web URL: http://www.tandfonline.com/doi/abs/10.3155/1047-3289.59.11.1258
Abstract: The Texas Environmental Research Consortium (TERC) funded significant components of the Second Texas Air Quality Study (TexAQS II), including the TexAQS II Radical and Aerosol Measurement Project (TRAMP) and instrumented flights by a Piper Aztec aircraft. These experiments called attention to the role of short-lived radical sources such as formaldehyde (HCHO) and nitrous acid (HONO) in increasing ozone productivity. TRAMP instruments recorded daytime HCHO pulses as large as 32 parts per billion (ppb) originating from upwind industrial activities in the Houston Ship Channel, where in situ surface monitors detected HCHO peaks as large as 52 ppb. Moreover, Ship Channel petrochemical flares were observed to produce plumes of apparent primary HCHO. In one such combustion plume that was depleted of ozone by large emissions of oxides of nitrogen (NOx), the Piper Aztec measured a ratio of HCHO to carbon monoxide (CO) 3 times that of mobile sources. HCHO from uncounted primary sources or ozonolysis of underestimated olefin emissions could significantly increase ozone productivity in Houston beyond previous expectations. Simulations with the CAMx model show that additional emissions of HCHO from industrial flares or mobile sources can increase peak ozone in Houston by up to 30 ppb. Other findings from TexAQS II include significant concentrations of HONO throughout the day, well in excess of current air quality model predictions, with large nocturnal vertical gradients indicating a surface or near-surface source of HONO, and large concentrations of nighttime radicals (~30 parts per trillion [ppt] HO2). HONO may be formed heterogeneously on urban canopy or particulate matter surfaces and may be enhanced by organic aerosol of industrial or motor vehicular origin, such as through conversion of nitric acid (HNO3). Additional HONO sources may increase daytime ozone by more than 10 ppb. Improving the representation of primary and secondary HCHO and HONO in air quality models could enhance the simulated effectiveness of control strategies.

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