OPEN-PATH TRANSMISSOMETRY TO DETERMINE ATMOSPHERIC EXTINCTION EFFICIENCY ASSOCIATED WITH FEEDYARD DUST

Open-lot, concentrated animal feeding operations (CAFOs) in the southern High Plains, such as cattle feedyards and open-lot dairies, generate fugitive emissions of particulate matter that occasionally reduce downwind visibility. The long-path visibility transmissometer (LPV) is used to measure total atmospheric extinction, a direct measure of path-averaged visibility impairment. To our knowledge, no researchers have used transmissometry to quantify aerosol concentrations downwind of open-lot livestock facilities. This work compares time-resolved PM10 mass concentration (g m-3) and atmospheric extinction (km-1) data measured simultaneously along the downwind boundary of a commercial cattle feedyard to compute "extinction efficiency," which is the change in atmospheric extinction that results from a unit change in PM mass concentration. Expected values for the actual extinction efficiency (as contrasted with dry extinction efficiency) of total suspended particulate (TSP) and its fraction less than 10 microns aerodynamic equivalent diameter (PM10) are 0.2-0.4 and 0.3-2.9 m2 g-1, respectively. Determination of the humidity-dependent atmospheric extinction efficiency of feedyard dust will facilitate the use of transmissometry as an intuitive, reliable, and real-time surrogate for measuring PM mass concentration.

OPEN-PATH TRANSMISSOMETRY TO DETERMINE ATMOSPHERIC EXTINCTION EFFICIENCY ASSOCIATED WITH FEEDYARD DUST Academic Article