Gaseous nitrogen emissions from anaerobic swine lagoons: Ammonia, nitrous oxide, and dinitrogen gas

Seventy-five percent of swine (Sus scrofa) production systems in North Amer ica use anaerobic or liquid-slurry systems for waste holding or disposal. A ccurate emissions data and emission factors are needed for engineering, pla nning, and regulatory agencies. These data are used For system design and e valuation of the effect of animal concentrations on the regional soil, surf ace and ground waters, and atmospheric environments. Noninvasive techniques were used to evaluate trace gases without disturbing the meteorology or la goon system being measured. Micrometeorological and gas sensors were mounte d on a submersible barge in the renter of the lagoon for use with flux-grad ient methodology to determine trace gas fluxes, without disturbing atmosphe ric transport processes, over extended periods. Collateral measurements inc luded lagoon nutrient, dissolved gas concentrations, and sludge gas mass fl ux. Ammonia emissions varied diurnally and seasonally and were highly corre lated with windspeed and water temperature. Nutrient loading measurements s howed that mobile ions, which were nonvolatile, were constant throughout fo ur successive lagoons. Immobile ions concentrated primarily in the sludge l ayer of the first lagoon. Measurements of denitrification N-2 losses sugges t as much N-2-N lost as from NH3-N. Ammonia gas emissions are not as large a percentage of total nitrogen input to the lagoons as previously thought b ut unaccounted-for nitrogen requires further research.