Assessing the emission sources and reduction potential of atmospheric ammonia at an urban site in Northeast China

Atmospheric ammonium and ammonia have brought negative environmental impacts and adverse health effects. However, ammonia emissions are generally less regulated worldwide. This study analyzed ammonium pollution character, quantified the dominant ammonia emission sources, and assessed ammonia reduction potential in urban Harbin (China). The results showed that ammonium recorded low concentration in the non-heating season (1.34 ± 1.57 μg/m³), and recorded sharply increased concentration (6.50 ± 7.02 μg/m³) and relative abundance in the heating season. It was closely correlated with vehicle-related pollutants (CO) in non-heating season, while with biomass burning-related pollutants (K⁺, Cl⁻) in the heating season. Bayesian Mixing Model emphasized the increasing contribution of biomass burning and decreasing contribution of fertilizer as the pollution levels escalate. The results from the thermodynamic equilibrium model showed that a 50%–60% ammonium decrease could bring marketable decrements of the aerosol pH, aerosol water content, ammonium nitrate concentration, and inorganic ion mass. The results of this study would provide scientific bases for ammonia emission reduction and haze pollution control in urban Harbin.