High efficiency of livestock ammonia emission controls in alleviating particulate nitrate during a severe winter haze episode in northern China

Abstract

Although nitrogen oxide (NOx ) emission controls have been implemented for several years, northern China is still facing high particulate nitrate (NO-3 ) pollution during severe haze events in winter. In this study, the thermodynamic equilibrium model (ISORROPIA-II) and the Weather Research and Forecast model coupled with chemistry (WRFChem) were used to study the efficiency of NH3 emission controls on alleviating particulate NO-3 during a severe winter haze episode.We found that particulate-NO-3 formation is almost NH3-limited in extremely high pollution but HNO3- limited on the other days. The improvements in manure management of livestock husbandry could reduce 40% of total NH3 emissions (currently 100 kt month-1) in northern China in winter. Consequently, particulate NO-3 was reduced by approximately 40% (on average from 40.8 to 25.7 μgm-3). Our results indicate that reducing livestock NH3 emissions would be highly effective in reducing particulate NO-3 during severe winter haze events.