Particulate matter emission rates from beef cattle feedlots in Kansas—Reverse dispersion modeling

Abstract

Open beef cattle feedlots emit various air pollutants, including particulate matter (PM) with equivalent aerodynamic diameter of 10 μm or less (PM₁₀); however, limited research has quantified PM₁₀ emission rates from feedlots. This research was conducted to determine emission rates of PM₁₀ from large cattle feedlots in Kansas. Concentrations of PM₁₀ at the downwind and upwind edges of two large cattle feedlots (KS1 and KS2) in Kansas were measured with tapered element oscillating microbalance (TEOM) PM₁₀ monitors from January 2007 to December 2008. Weather conditions at the feedlots were also monitored. From measured PM₁₀ concentrations and weather conditions, PM₁₀ emission rates were determined using reverse modeling with the American Meteorological Society/U.S. Environmental Protection Agency Regulatory Model (AERMOD). The two feedlots differed significantly in median PM₁₀ emission flux (1.60 g/m²-day for KS1 vs. 1.10 g/m²-day for KS2) but not in PM₁₀ emission factor (27 kg/1000 head-day for KS1 and 30 kg/1000 head-day KS2). These emission factors were smaller than published U.S. Environmental Protection Agency (EPA) emission factor for cattle feedlots.

Implications

This work determined PM₁₀ emission rates from two large commercial cattle feedlots in Kansas based on extended measurement period for PM₁₀ concentrations and weather conditions, and reverse dispersion modeling, providing baseline information on emission rates for cattle feedlots in the Great Plains that could be used for improving emissions estimates. Within the day, PM emission rates were generally highest during the afternoon period; PM emission rates also increased during early evening hours. In addition, PM emission rates were highest during warm season and prolonged dry periods. Particulate control measures should target those periods with high emission rates.

Acknowledgments

This study was supported by U.S. Department of Agriculture (USDA) National Institute of Food and Agriculture Special Research Grant “Air Quality: Reducing Air Emissions from Cattle Feedlots and Dairies (TX and KS)” through the Texas AgriLife Research and by Kansas Agricultural Experiment Station. Some of the meteorological data were obtained from the Atmospheric Radiation Measurement (ARM) Program sponsored by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research, Climate and Environmental Sciences Division. Technical assistance provided by Darrell Oard, Dr. Jasper Tallada, Dr. Li Guo, Kevin Hamilton, and Howell Gonzales of Kansas State University; Sheraz Gill of San Joaquin Valley Air Pollution Control District; and Dr. James Thurman of EPA is acknowledged. Cooperation of feedlot operators and KLA Environmental Services, Inc., is also acknowledged.