Atmospheric Ammonia Emissions from a Dairy

Gaseous ammonia (NH₃) emissions at high concentrations can damage human and animal respiratory systems. NH₃ environmental impacts include aerosol formation, altering atmospheric chemistry, terrestrial and aquatic eutrophication, soil acidification and global warming. Preindustrial NH₃ emissions are estimated to be 21 Tg yr^-1 while current emissions are estimated to be 47 Tg yr^-1 with most of the increase coming from domestic animals (Galloway et al., 1995). There is a lack of detailed emission data from the United States and there are many problems with applying emissions estimates from Europe due to the difference in farming practices between the two regions. Feed and manure management practices can have a large impact on emissions. We are studying NH₃ emissions at the WSU dairy located near Pullman, WA to provide a detailed emission inventory of the various sources at the dairy. The dairy has approximately 170 milking cows housed in open air barns and the waste from the milking cows is stored in liquid slurry lagoons until it is applied to grass fields in the late summer. NH₃ is measured using a short-path spectroscopic absorption near 200 nm with a sensitivity of a few ppbv and a time resolution of a few seconds. The open air short-path method is advantageous because it is self calibrating and avoids inlet wall adherence which is a major problem for most NH₃ measurement techniques. As part of the detailed emission inventory, NH₃ fluxes were determined from the milking stalls, main slurry lagoon and the application of slurry to the fields with a large sprinkler using a SF₆ tracer technique and a dense point Gaussian plume model. NH₃ emission fluxes from various parts of the dairy will be presented.