Particulate Emissions from a Beef Cattle Feedlot Using the Flux-Gradient Technique
2014
Bonifacio, Henry F. | Maghirang, Ronaldo G. | Trabue, Steven L. | McConnell, Laura L. | Prueger, John H. | Razote, Edna B.
Data on air emissions from open-lot beef cattle (Bos taurus) feedlots are limited. This research was conducted to determine fluxes of particulate matter with an aerodynamic diameter ≤10 μm (PM₁₀) from a commercial beef cattle feedlot in Kansas using the flux-gradient technique, a widely used micrometeorological method for air emissions from open sources. Vertical PM₁₀ concentration profiles and micrometeorological parameters were measured at the feedlot using tapered element oscillating microbalance PM₁₀ samplers and eddy covariance instrumentations (i.e., sonic anemometer and infrared hygrometer), respectively, from May 2010 through September 2011, representing feedlot conditions with air temperatures ranging from −24 to 39°C. Calculated hourly PM₁₀ fluxes varied diurnally and seasonally, ranging up to 272 mg m⁻² h⁻¹, with an overall median of 36 mg m⁻² h⁻¹. For warm conditions (air temperature of 21 ± 10°C), the highest hourly PM₁₀ fluxes (range 116–146 mg m⁻² h⁻¹) were observed during the early evening period, from 2000 to 2100 h. For cold conditions (air temperature of −2 ± 8°C), the highest PM₁₀ fluxes (range 14–27 mg m⁻² h⁻¹) were observed in the afternoon, from 1100 to 1500 h. Changes in the hourly trend of PM₁₀ fluxes coincided with changes in friction velocity, air temperature, sensible heat flux, and surface roughness. The PM₁₀ emission was also affected by the pen surface water content, where a water content of at least 20% (wet basis) would be sufficient to effectively reduce PM₁₀ emissions from pens by as much as 60%.
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