Observations and Modeling of Ozone Photochemistry in Plumes from Petrochemical Facilities near Houston, TX.

Comprehensive airborne measurements of ozone and its precursors, as well as other secondary photochemical products were made during the Texas 2000 Air Quality Study in the plumes of power plants, petrochemical facilities and the Houston urban plume. These measurements indicate particularly rapid and efficient ozone formation as a result of the collocation of significant emissions of NOx and reactive alkenes (mainly ethene and propene) at some of the petrochemical facilities. In a two dimensional Lagrangian plume model the emission rates of NOx, as well as, ethene and propene were adjusted by comparison with the observations downwind from isolated petrochemical facilities. While adopted and reported NOx emission rates compare reasonably well for these facilities, the reported alkene emission rates are much lower than the observation based estimates. The model, using the observation based emission rates, reproduces the observed formation of ozone and other secondary products such as formaldehyde, acetaldehyde and the partitioning of the reactive nitrogen species well in the plumes of petrochemical facilities.