Concentration, Size Distributions, and Transport of Agricultural Aerosols

Naruki Hiranuma
Texas A&M Univ.,
College Station, Texas

Agricultural fugitive dust is a significant source of localized air pollution in the semi-arid southern Great Plains. In the Texas Panhandle, daily episodes of ground-level fugitive dust emissions from the cattle feedlots associated with increased cattle activity in the early evenings are routinely observed. Here we present measurements of the concentrations and size distributions of agricultural aerosols measured at the nominal downwind edge of the open-air cattle feedlot during summers of 2006, 2007 and 2008. A GRIMM sequential mobility particle sizer and GRIMM 1.108 aerosol spectrometer were used to measure aerosol size distributions in the range of 10 nm to 10 Ám aerodynamic diameter. In addition to these continuous measurements at the downwind site, size distributions measurements collected further downwind (~5 km) will be used to observe and quantify aerosol dispersion and transport. In additional, coincident measurements of the aerosol hygroscopicity, chemical composition, and gas and particulate ammonia concentrations were collected at the feedlot. Relationships between these fundamental properties and the fate and transport of the aerosols will be discussed. The results of this study will provide important particulate emission data from a feedyard which is needed to improve our understanding of the role of agricultural particulates in local and regional air quality.