TSP, PM₁₀, and PM_2.5 emissions from a beef cattle feedlot using the flux-gradient technique

Emissions data on air pollutants from large open-lot beef cattle feedlots are limited. This research was conducted to determine emissions of total suspended particulates (TSP) and particulate matter (PM₁₀ and PM_2.5) from a commercial beef cattle feedlot in Kansas (USA). Vertical particulate concentration profiles at the feedlot were measured using gravimetric samplers, and micrometeorological parameters were monitored with eddy covariance instrumentation during the nine 4- to 5-day intensive sampling campaigns from May 2010 through September 2011. Emission fluxes were determined from the measured concentration gradients and meteorological parameters using the flux-gradient technique. PM ratios based on calculated emission fluxes were 0.28 for PM_2.5/PM₁₀, 0.12 for PM_2.5/TSP, and 0.24 for PM₁₀/TSP, indicating that a large fraction of the PM emitted at the studied feedlot was in the coarse range of aerodynamic diameter, >10 μm. Median daily emission factors were 57, 21, and 11 kg 1000-head (hd)^-1 d^-1 for TSP (n = 20 days), PM₁₀ (n = 19 days), and PM_2.5 (n = 11 days), respectively. Cattle pen surface moisture contents of at least 20-30% significantly reduced both TSP and PM₁₀ emissions, but moisture's effect on PM_2.5 emissions was not established due to difficulty in measuring PM_2.5 concentrations under low-PM conditions.