This study evaluates the performance of AERMOD, the current U.S. Environmental Protection Agency (EPA) regulatory model, in simulating particulate matter (PM 10 and PM 2.5 ) dispersion from a poultry pullet facility. At the source, the daily mean PM 10 and PM 2.5 concentrations with strong diurnal patterns were estimated to be 436.01 ± 166.77 μg m −3 and 291.09 ± 105.81 μg m , respectively. The modeled hourly PM concentration showed acceptable accuracy relative to the measured PM concentrations downwind of the source. Increasing the averaging period from hourly to daily resulted in improved prediction. The simulations revealed that PM concentrations at and beyond the property line of the poultry facility were within the National Ambient Air Quality Standards. This study suggested that AERMOD is effective in predicting and assessing the impacts of PM downwind of poultry facilities.Implications: Sampling and monitoring of PM emission around concentrated animal feeding operations (CAFOs) can be both time-consuming and costly. This makes dispersion modeling an alternative method for air quality assessment around CAFOs. The acceptable performance of the current EPA regulatory model, AERMOD, in modeling PM 10 and PM 2.5 dispersion around the pullet poultry facility suggested that this model can effectively predict PM downwind concentrations at and around CAFOs and can be used as a tool to assess the impacts of PM at downwind locations.
Open-lot, concentrated animal feeding operations (CAFOs) in the southern High Plains, such as cattle feedyards and open-lot dairies, generate fugitive emissions of particulate matter that occasionally reduce downwind visibility. The long-path visibility transmissometer (LPV) is used to measure total atmospheric extinction, a direct measure of path-averaged visibility impairment. To our knowledge, no researchers have used transmissometry to quantify aerosol concentrations downwind of open-lot livestock facilities. This work compares time-resolved PM 10 mass concentration (µg m-3) and atmospheric extinction (km-1) data measured simultaneously along the downwind boundary of a commercial cattle feedyard to compute "extinction efficiency," which is the change in atmospheric extinction that results from a unit change in PM mass concentration. Expected values for the actual extinction efficiency (as contrasted with dry extinction efficiency) of total suspended particulate (TSP) and its fraction less than 10 microns aerodynamic equivalent diameter (PM 10) are 0.2-0.4 and 0.3-2.9 m 2 g-1 , respectively. Determination of the humidity-dependent atmospheric extinction efficiency of feedyard dust will facilitate the use of transmissometry as an intuitive, reliable, and real-time surrogate for measuring PM mass concentration.
The flow and dispersion around the obstacles is important to understand the pollution problem in the urban areas. This study presents the preliminary results of the experiment carried out at Dugway Proving Ground, Utah. It shows that the presence of obstacles has a significant effect on the structure of the plume. Both horizontal plume spread (σ y ) and vertical plume spread (σ z ) are higher in arrays of obstacles compared to without obstacle configuration. It is also observed that the concentrations in arrays of obstacles are generally lower than those without obstacles. The modeling results show that the Gaussian plume model for the timeaveraged concentration in the near-field can provide important information with few input parameters. The information obtained from the controlled conditions of the model canopy can be useful for interpreting data from real urban areas.
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