Analysis of an Industrial Plume in Texas City, TX

During the Second Texas Air Quality Study (TexAQS-II) the Baylor University Aztec aircraft was able to follow a plume originating from the industrial complex in Texas City on September 20, 2006. Aboard instrumentation allowed for measurements of formaldehyde (HCHO), ozone (O3), nitrogen oxides (NO/NO2), carbon monoxide (CO), and sulfur dioxide (SO2). The HCHO measurements indicate that HCHO/CO ratios may vary with aging of this industrial plume. Smallest ratios are found closer to the emission source and suggest that HCHO emissions are up to 2-4% of the CO emissions found in this plume. In this area of the plume no obvious photochemical production occurs as identified by almost constant Ox values and thus indicating the primary nature of this HCHO. In this plume area HCHO is highly correlated with SO2 making the latter compound an ideal surrogate to track this emission source. HCHO emissions were found to be up to 18% of the SO2 emissions in this plume. We utilized the Community Multiscale Air Quality (CMAQ) model to further investigate the processes and reactions in this plume. From the observations and modeling results we conclude that apart from traffic-related primary HCHO emissions industrial releases of HCHO may be non-negligible and may potentially serve as an appreciable source for OH in the early morning.