The Relative Importance of Primary and Oxidized Hydrocarbons in the Houston Urban and Ship Channel Plumes

During the Texas Air Quality Study (TexAQS 2000) an in-situ gas chromatograph was used on board the National Center for Atmospheric Research (NCAR) Electra aircraft for the acquisition and immediate analysis of ambient air samples for light alkanes, alkenes, aldehydes, ketones, alcohols, benzene and toluene. In addition, canister samples were acquired for later analysis for a larger group of NMHCs. These data, together with fast measurements of ozone, formaldehyde, CO2 and a smaller group of NMHCs by proton transfer mass spectrometer (PTr-MS) have been used to demonstrate the dominant role played by light alkenes and aldehydes in ozone production downwind of the dense Houston 'Ship Channel' petrochemical complex. In addition, significant slower ozone production capacity from both the 'Ship Channel' complex and the surrounding urban region is shown to be exported in the form of ketones and alcohols. The localized nature of the predominant source region of propene in particular, allows a rough estimate of its surface source strength to be made from the aircraft acquired data. This analysis indicates that current available emissions inventory data may seriously underestimate such emissions