A survey of total nitrogen abundance in pullet and laying hen houses in Alberta, Canada

Ammonia (NH3) is the most abundant alkaline gas in the atmosphere and a major contributor to aerosol formation in ambient air, impacting climate and human health. Agricultural practices are a major atmospheric source of NH3 in the troposphere, yet observations of N-based compounds in agricultural settings have been sparse. This paper describes measurements of total nitrogen (Nt) and carbon dioxide (CO2) in 14 Alberta laying hen facilities. Mixing ratios of Nt and nitrogen oxides (NO and NOx) were monitored using a commercial chemiluminescence (CL) instrument equipped with an automated inlet filter valve to differentiate between gas-phase and total (i.e., gasand aerosol-) phase, and mixing ratios of CO2 were monitored using a non-dispersive infrared sensor (NDIR). The Nt budget was dominated by gas-phase NH3 whose mixing ratio varied greatly between barns, from 0.2 to 16 parts-per-million by volume (ppmv) and median level of 2.1 ppmv, compliant with the industry's NH3 standard of < 25 ppmv. Observed NOx levels were in the range of 1.5 to 22.3 parts-per-billion by volume (ppbv), median 11.3 ppbv, and were negligible compared to Nt. Mixing ratios of CO2 ranged from 629 to 2185 ppmv (median 1639 ppmv). Emission rates (ER) of NH3 were estimated from the observed CO2 enhancements relative to ambient air and an assumed ER of CO2 of 71.5 g d-1 bird-1 which ranged from 0.005 to 0.136 g d-1 bird-1 (median 0.046 g d-1 bird-1). This work is the first examination of air quality in Alberta poultry barns from a total nitrogen perspective and sets a baseline for future studies.