We report on ancillary VOC and aerosol observations made at two air quality monitoring locations operated by the Texas Commission on Environmental Quality (TCEQ). These ancillary observations were made as part of ‘The Houston Triangle Campaign', a component of the larger Texas 2006 Air Quality Study.

The observations compliment other results presented at this conference by Berkowitz et al and Yu et al. Team members deployed an Aerodyne Time-of-Flight Aerosol Mass Spectrometer (C-ToF AMS) and an Ionicon Proton Transfer Mass Spectrometer (PTR-MS) at Deer Park (near the Houston Ship Channel) and an Aerodyne Quadrupole Aerosol Mass Spectrometer (Q-AMS) and an Ionicon PTR-MS at Bayland Park (on the west side of Houston) between September 15 and September 28, 2006. The AMS instruments measure simultaneous size distribution and composition of aerosol particles from approximately 50 to 100 microns while the PTR-MS measures volatile organic compounds (VOC) from 30-200 amu with detection limits of 50-100 ppt . Compounds measured by the AMS are limited to non-refractory species due to the method of vaporization and ionization, pyrolysis followed by electron impact.

AMS data taken at Deer Park and Bayland Park indicated that the particulate chemical composition at both sites exhibited either predominantly organic or predominantly sulfate species depending on the wind direction and other meteorological factors. These variations will be presented and discussed along with correlations with the VOC data from the PTR-MS instruments and other trace gas data. Source correlation using aerosol species, trace gases and meteorological data will be discussed. In particular, the AMS organic mass spectra will be deconvoluted into several classes of organic species using multivariate analysis techniques such as PCA (principle components analysis) or PMF (positive matrix factorization). Of particular interest will be the relative importance of hydrocarbon-like organic aerosol (HOA), which can often be an indicator of primary or directly emitted organic aerosol (POA), and different types of oxygenated organic aerosol (OOA) which are indicative of fresh or aged secondary organic aerosol (SOA). We will apply available SOA formation mechanisms in the comprehensive sectional aerosol box-model, Model for Simulating Aerosol Interactions and Chemistry (MOSAIC) to the time-correlated data from the AMS, PTR-MS and trace gas measurements evaluate gas-particle partitioning of semi-volatile organic species.