氨气是大气酸性成分的主要中和剂，是影响区域空气质量、大气能见度以及酸性沉降的重要因素。研制了基于开放光程近红外可调谐半导体激光吸收光谱(Tunable diode laser absorption spectroscopy，TDLAS)技术的大气NH；浓度连续监测系统，并对北京城区大气NH₃浓度进行了两个星期的连续检测。检测结果表明，北京城区大气具有较高的NH₃浓度，且具有明显的日变化周期特征，基本特点是白天浓度低，夜晚浓度高且变化相对平缓。相关性研究表明，非农业排放源，特别是城市交通的机动车尾气排放是北京城区大气NH₃的主要来源。

Gaseous ammonia is the most important neutralization agent of atmospheric acids,it plays an important role in regional air quality,atmospheric visibility,and acid deposition. An open-path near infrared tunable diode laser absorption spectroscopy(TDLAS) based on atmospheric NH₃ successive monitor system has been developed,and has been used to achieve successive measurements of atmospheric NH₃ concentration in the urban area of Beijing for two weeks. The experimental results show that the atmospheric NH₃ concentration in the urban area of Beijing is high,and has a very clear diurnal variation cycle,,the general characteristics of diurnal variation are the lowest value in the daytime and the highest value at night. Correlation studies show that the nonagricultural emission is the main contribution of atmosphere NH₃ in the urban area of Beijing,especially the emissions of city transportation vehicles