ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-10-9487-2010 Occurrence of gas phase ammonia in the area of Beijing (China) Ianniello A. 1 Spataro F. 1 Esposito G. 1 Allegrini I. 1 Rantica E. 1 Ancora M. P. 1 Hu M. 2 Zhu T. 2 CNR – Institute of Atmospheric Pollution Research, Via Salaria Km 29.3, CP10, 00015 Monterotondo S., Rome, Italy State Key Joint Laboratory for Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, China 07 10 2010 10 19 9487 9503 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/10/9487/2010/acp-10-9487-2010.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/10/9487/2010/acp-10-9487-2010.pdf

The atmospheric concentrations of gaseous ammonia have been measured during two field campaigns in the winter and in the summer of 2007 at Beijing (China). These measurements were carried out by means of diffusion annular denuders coated with phosphorous acid. The results were discussed from the standpoint of temporal and diurnal variations and meteorological effects. The daily average NH<sub>3</sub> concentrations were in the range of 0.20–44.38 μg/m<sup>3</sup> and showed regular temporal variations with higher concentrations during summer and with lower during winter. The temporal trends seemed to be largely affected by air temperature because of agricultural sources. No diurnal variability was observed for gaseous NH<sub>3</sub> levels in both winter and summer seasons. The highest ammonia value of 105.67 μg/m<sup>3</sup> was measured in the early morning during the summer period when stable atmospheric conditions occurred. The diurnal winter and summer trends of ammonia showed a weak dependence on the air temperature and they were affected nearly by wind direction suggesting regional and local source influences. Ammonia was also correlated with the atmospheric mixing in the boundary layer, and, with NO<sub>x</sub>, CO and PM<sub>2.5</sub> air concentrations supporting the hypothesis that the traffic may be also an important source of ammonia in Beijing.

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