A model-based exploratory study of sulfur dioxide dispersions from concentrated animal feeding operations in the Southeastern United States

In the Southeastern U. S. there are Concentrated Animal Feeding Operations (CAFOs) that emit a variety of gases, including SO2. Sulfur is emitted as reduced sulfur compounds and can react in the atmosphere to produce SO2. It is expected that the concentration and spread of SO2 emissions from these sources would differ between wet and dry periods. In this research, SO2 emissions from locations representing CAFOs and its dispersion over the southeastern U.S. were simulated through sensitivity experiments using the Weather Research and Forecasting-Chemistry (WRF- Chem) model. Simulations were performed for dry periods and precipitation events that occurred over western Kentucky between July 7 and 13 July 2012. The study found that spatial coverage of SO2 dispersion originating from these locations was reduced during precipitation events and expanded during dry periods. The average concentration of SO2 over the study area was also higher during the breaks between precipitation events than during precipitation. The highest concentrations of SO2 exceeding 1,000 pptv remained within close range of the emission locations for the majority of the simulations, except for when local surface wind speeds were high. Most emissions from the locations remained limited to the surface and lower levels of the atmosphere (850 mb).