Particulate emissions from a beef cattle feedlot using the flux-gradient technique

Area of Science:

• Environmental Science
• Agricultural Engineering
• Atmospheric Science

Background:

• Limited data exists on air emissions from open-lot beef cattle feedlots.
• Particulate matter (PM) emissions are a concern for air quality and animal agriculture.

Purpose of the Study:

• To quantify particulate matter (PM) fluxes from a commercial beef cattle feedlot.
• To investigate diurnal and seasonal variations in PM emissions.
• To assess the impact of environmental factors on PM emissions.

Main Methods:

• Utilized the flux-gradient technique, a micrometeorological method for measuring air emissions.
• Employed tapered element oscillating microbalance PM samplers and eddy covariance instrumentation.
• Collected data over 16 months across a wide temperature range (-24 to 39°C).

Main Results:

• Hourly PM fluxes varied diurnally and seasonally, with a median of 36 mg m⁻² h⁻¹ and peaks up to 272 mg m⁻² h⁻¹.
• Warm conditions showed highest PM fluxes in the early evening, while cold conditions peaked in the afternoon.
• PM emissions were strongly correlated with friction velocity, temperature, sensible heat flux, and surface roughness.

Conclusions:

• Pen surface water content significantly impacts PM emissions; ≥20% moisture reduced emissions by up to 60%.
• Understanding these emission dynamics is crucial for developing effective mitigation strategies in cattle feedlots.