Investigating the Role of Coastal Atmospheric Processes and Fumigation Phenomenon in Air Pollutant Dispersion along the Gulf of Mexico Coast

The Gulf of Mexico coastal region (GCR) houses numerous oil refineries, including the Motiva refinery in Port Arthur, Texas, which significantly impact air quality by emitting various pollutants into the atmosphere. Understanding the dispersion and transport of these pollutants is crucial for assessing their impacts on coastal communities and marine ecosystems. In this modeling study of the summer of 2015, we investigated the dispersion of pollutants emitted from the refinery, with a specific focus on the influence of sea-land breeze circulation. Utilizing the CALPUFF model and high-resolution meteorological data downscaled from the Weather Research and Forecasting (WRF) model to 3 km, we examined the diurnal variability of wind and various air pollutants (PM10, PM2.5, SO2, NOx, and CO) in the GCR. During the daytime, from 7 am to 17 pm, a remarkable decrease in pollutant concentrations was observed. This decrease was attributed to the development of sea breeze, wherein cooler air from the sea replaced rising warm air over the land. The analysis demonstrates the potential benefits of increasing mixing height during sea breeze conditions, which contributes to enhanced pollutant dispersion and improved air quality management strategies in coastal areas. As the sea breeze advanced inland, it effectively dispersed the pollutants emitted from the refinery, resulting in reduced concentrations in the coastal region. The research findings reveal the crucial role of stack height and its interaction with the sea-land breeze in enhancing pollutant dispersion in the Gulf of Mexico coastal region. This study aimed to dissect the impact of fumigation on pollutant dispersion by conducting a comprehensive analysis using the WRF/CALPUFF modeling under varying boundary conditions. Three distinct scenarios were examined: a baseline scenario without specific boundary effects, a lake boundary scenario considering the lake's influence on concentration of pollutants, and a Gulf boundary scenario exploring the Gulf's impact. Surprisingly, while it was expected that the Gulf's vast expanse would strongly influence fumigation, results showed minimal impact on pollutant concentration. This led to a closer examination of other potential factors that might have a greater impact than the Gulf boundary, such as the distance of emission sources from the Gulf.