Particulate matter emission rates from beef cattle feedlots in Kansas-reverse dispersion modeling

Open beef cattle feedlots emit various air pollutants, including particulate matter (PM) with equivalent aerodynamic diameter of 10 microm 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.     

Laboratory evaluation of dust-control effectiveness of pen surface treatments for cattle feedlots

Emission of particulate matter (PM) is one of the major air quality concerns for large beef cattle feedlots. Effective treatments on the uncompacted soil and manure mixture of the pen surface may help in reducing PM emission from feedlots. A laboratory apparatus was developed for measuring dust-emission potential of cattle feedlot surfaces as affected by pen surface treatments. The apparatus was equipped with a simulated pen surface, four mock cattle hooves, and samplers for PM with equivalent aerodynamic diam. ≤ 10 μm (PM(10)). The simulated pen surface had a layer of dry, loose feedlot manure with a compacted soil layer underneath. Mock hooves were moved horizontally on the manure layer to simulate horizontal action of cattle hooves on the pen surface. High-volume PM samplers were used to collect emitted dust. Effects of hoof speed, depth of penetration, and surface treatments with independent candidate materials (i.e., sawdust, wheat straw, hay, rubber mulch, and surface water application) on PM(10) emission potential of the manure layer were investigated. Our laboratory study showed PM(10) emission potential increased with increasing depth of penetration and hoof speed. Of the surface treatments evaluated, application of water (6.4 mm) and hay (723 g m(-2)) exhibited the greatest percentage reduction in PM(10) emission potential (69 and 77%, respectively) compared with the untreated manure layer. This study indicated application of hay or other mulch materials on the pen surface might be good alternative methods to control dust emission from cattle feedlots.