Persistent Nonagricultural and Periodic Agricultural Emissions Dominate Sources of Ammonia in Urban Beijing: Evidence from 15N Stable Isotope in Vertical Profiles

• DOI: 10.1021/acs.est.9b05741
• Publication Date: 2019-12-10T03:47:36Z
• Authors: Yangyang Zhang; Katherine B. Bene...; Aohan Tang; Yele Sun; Yunting Fang; Xuejun Liu
• Keywords: Apportionment; Mixing ratio

Ammonia (NH3) emission reduction is key to limiting the deadly PM2.5 pollution globally. However, studies of long-term source apportionment vertical NH3 are relatively limited. On basis one-year measurements weekly profiles δ15N–NH3 at 5 heights (2, 15, 102, 180, and 320 m) on a 325-m meteorological tower in urban Beijing, we found that concentrations generally remained stable with height. increased obviously as function height cold seasons (with heating) decreased warm fertilization), indicating stronger human-induced seasonal variation via regional transport higher altitudes. Relatively near ground surface suggested strong local emission. The results isotopic mixing model (SIAR) indicate using measured only would overestimate contribution agricultural emissions NH3. By an estimation initial δ15N–NH3, nonagricultural sources contributed ∼72% average. Our study suggests (i) both persistent periodic drive atmospheric concentration its distribution Beijing; (ii) based likely underestimates fossil fuel contribution, if combined NHx isotope effects not considered.