Review on ammonia in ambient air:sampling,measurement and source apportionment via nitrogen isotopes
Gaseous ammonia(NH3)is a key precursor in the formation of PM2.5 in the atmosphere.To enhance the precision of identifying NH3 sources through isotopic techniques and alleviate urban air PM2.5 pollution,this paper reviews recent researches on the following aspects:methods for sampling and quantifying gaseous NH3,techniques for determining or estimating its nitrogen isotope ratios,the nitrogen isotope compositions and fractionations of NH3 in air and emitted from diverse sources,the isotopic compositions of NH4 in atmospheric particulate matter and rain-fall,as well as the source apportionment of atmospheric NH3.Several recommendations for future research are ac-cordingly proposed.The minimum amount of samples should be determined before collecting air samples with passive method considering nitrogen isotope fractionation of NH3.It is necessary to clarify the nitrogen isotope compositions of ammonia from biomass combustion,natural soils,oceans,sewage plants,vegetation,and other potential sources.The nitrogen isotopic variation mechanism for ammonia from diverse sources needs to be further investigated.Both mass concentrations and isotopic compositions of gaseous NH3 and particulate NH4+should be measured simultane-ously with higher temporal resolution to explore the mechanism of nitrogen isotope fractionation during the formation of particulate NH4+.Additionally,exploring the isotopic fractionation of gaseous NH3 under diverse meteorological conditions and air pollution status is recommended.
万方数据
维普
