Distribution of Particulate Matter and Affiliated Chemicals Emitted from Beef Cattle Feedyards

Within the west Texas region, beef cattle feedyards are a source of particulate matter (PM). This PM is comprised mostly of manure, and has previously been implicated as a mechanism of transport for manure-affiliated chemicals off of feedyards into the surrounding environment. Manure-affiliated chemicals include veterinary pharmaceuticals, administered to cattle for growth promotion and maintenance of health, that may have deleterious effects following exposure in non-target organisms. Previous research has documented steroids and antibiotics in feedyard-emitted PM; this dissertation provides the first quantitation of the beta agonist ractopamine in feedyard-emitted PM. Quantitation of these chemicals in PM has, to this point, been conducted within or adjacent to feedyard boundaries, which provides limited information with regards to fate in the environment. This dissertation examined the persistence of veterinary pharmaceuticals and elevated PM concentrations up to 5 km downwind of feedyards. Dramatic reductions in PM concentration and a corresponding reduction in pharmaceutical concentration (per m3 air) were observed in the first km downwind of feedyards; no reduction, however, was observed in pharmaceutical concentrations per g PM at any distance. To examine the transport of feedyard-emitted PM on a regional scale, dust storm samples in Lubbock, TX and a variety of source samples from the west Texas region were characterized based on both concentrations of trace elements and microbial community. Results indicate a difference in composition for dust storms on different dates, which entered Lubbock from different directions, including an increase in microbes associated with cattle operations in a storm that passed through a region with a high concentration of feedyards and dairies prior to reaching Lubbock. Overall, this research begins to address the data gaps that exist regarding the transport of feedyard PM and affiliated chemicals after they exit feedyard boundaries.