Time-varying PM10 emissions from open-lot dairies and cattle feedyards | Conference Paper individual record

Typical PM emission-factor studies for dairies and feedyards have involved measuring ground-level concentration as close to the plume centerline as weather predictions permit, followed by dispersion modeling using a single-valued emission factor to match the 24-hour average concentration. Using AERMOD as our dispersion-modeling platform, we confirm that the 24-hour average emission factor cannot reproduce the hourly average concentrations throughout the day and vastly underpredicts the magnitude of the evening dust peak. Moreover, matching a single concentration measurement near the plume centerline is not as rigorous a dispersion-modeling test as attempting to match an entire transverse cross-section of the plume along the downwind boundary. We report preliminary results of two intensive monitoring campaigns at an open-lot dairy and a cattle feedyard during summer 2009 in which seven real-time PM10 monitors were distributed across the downwind boundary of the open-lot area. Using AERMOD with a time-varying emission flux to match predicted and measured concentrations along the full, transverse cross-section of the aerosol plume. We show that, granting the constraints of the Gaussian modeling algorithm, the emission flux from open lots cannot be assumed time-invariant within a 24-hour period. Moreover, the time-variant emission fluxes estimated from one-hour average concentration data appear to confirm that (a) dust-emitting animal behaviors increase during a three- to four-hour interval around sundown in the feedyard and (b) vehicle traffic and the animals' feeding behavior during the morning hours contribute significantly to the daily average PM10 flux.

author list (cited authors)
Auvermann, B. W., Bush, K. J., Marek, G. W., Heflin, K., Wilhite, W. B., & Sakirkin, S.
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