Ambient Ammonia and Ammonium Observed at a Remote Mountain Site in Western China

摘要

The average concentration of NH_3 and NH_4~+ were 17.2±15.6 ppb and 0.57±0.34 □ μg/m~3 at WLG station. NH_3 concentrations were highest in summer and lowest in winter at WLG, while highest NH_4~+ concentrations occurred in summer. The soils emission, cattle grazing, air temperature and gas-to-particle conversion reactions have important influences on this seasonality. At WLG site, NH_3 is primarily in the gas phase during all seasons, and NH_x is strongly influenced by local NH_3 sources and dry deposition of NH_3. More future studies are needed to pin down the sources/causes of ammonia and ammonium aerosol in the remote atmosphere of western China, and to study the potential impacts of the transport of regional pollution from populated eastern China and from other parts of the world.