Atmospheric NH3 and NO2 concentration and nitrogen deposition in an agricultural catchment of Eastern China Original Research Article

To assess the atmospheric environmental impacts of anthropogenic reactive nitrogen in the fast-developing Eastern China region, we measured atmospheric concentrations of nitrogen dioxide (NO2) and ammonia (NH3) as well as the wet deposition of inorganic nitrogen (NO3− and NH4+) and dissolved organic nitrogen (DON) levels in a typical agricultural catchment in Jiangsu Province, China, from October 2007 to September 2008. The annual average gaseous concentrations of NO2 and NH3 were 42.2 μg m−3 and 4.5 μg m−3 (0 °C, 760 mm Hg), respectively, whereas those of NO3−, NH4+, and DON in the rainwater within the study catchment were 1.3, 1.3, and 0.5 mg N L−1, respectively. No clear difference in gaseous NO2 concentrations and nitrogen concentrations in collected rainwater was found between the crop field and residential sites, but the average NH3 concentration of 5.4 μg m−3 in residential sites was significantly higher than that in field sites (4.1 μg m−3). Total depositions were 40 kg N ha−1 yr−1 for crop field sites and 30 kg N ha−1 yr−1 for residential sites, in which dry depositions (NO2 and NH3) were 7.6 kg N ha−1 yr−1 for crop field sites and 1.9 kg N ha−1 yr−1 for residential sites. The DON in the rainwater accounted for 16% of the total wet nitrogen deposition. Oxidized N (NO3− in the precipitation and gaseous NO2) was the dominant form of nitrogen deposition in the studied region, indicating that reactive forms of nitrogen created from urban areas contribute greatly to N deposition in the rural area evaluated in this study.