Spatial-temporal variability of dry and wet deposition of atmospheric nitrogen in different ecological regions of Shaanxi

The objective of this experiment was to study the spatial-temporal variability of dry and wet deposition of atmospheric nitrogen in different ecological regions of Shaanxi Province. Measurements were made at five monitoring sites in four different ecological regions from November 2009 to October 2010. The amounts of total inorganic nitrogen( TIN) deposition were 4.7 kg / hm2at Yulin,11.9 kg / hm2at Luochuan,25.8 kg / hm2at Xi' an,31.9 kg / hm2at Yangling,and 19. 2 kg / hm2at Ankang. Wet deposition accounted for 62 to 96% of the TIN deposition,ranging from 2.9 kg / hm2at Yulin, 10.4 kg / hm2at Luochuan,24.8 kg / hm2at Xi'an,27.7 kg / hm2at Yangling,and 16.3 kg / hm2at Ankang. Dry deposition accounted for 4 to 38% of the TIN deposition,ranging from 1.8 kg / hm2at Yulin,1.5 kg / hm2at Luochuan,1.0 kg / hm2at Xi'an,4.1 kg / hm2at Yangling,and 2.9 kg / hm2at Ankang. Wet deposition and rainfall were positively correlated,whereas dry deposition and rainfall were negatively correlated. Ammonium nitrogen( NH+ 4-N) deposition amounts were 2.0 kg / hm2at Yulin,6.4 kg / hm2at Luochuan,17.0 kg / hm2at Xi' an,17.2 kg / hm2at Yangling,and 11.0 kg / hm2at Ankang. These amounts accounted for 44 to 66% of the TIN deposition. Nitrate nitrogen( NO-3-N) amounts were 2.6 kg / hm2at Yulin,5.5 kg / hm2at Luochuan,8.8 kg / hm2at Xi'an,14.7 kg / hm2at Yangling,and 7.3 kg / hm2at Ankang. These amounts made up34 to 56% of the TIN deposition. Nitrogen deposition is mainly in the form of NH+ 4-N in all regions except Yulin.