Preliminary Estimate of the Atmospheric Nitrogen Deposition in Different Ecological Regions of Shaanxi Province

Five monitoring sites were chosen in four different ecological regions of Shaanxi Province to conduct a one-year monitoring research on wet and dry nitrogen deposition,which was aimed to make preliminary estimate of the atmospheric nitrogen deposition amount in different ecological regions.The results showed that the amount of total inorganic nitrogen(TIN)ranged from 8.25 to 16.12 kg·hm-2 in the 5 monitoring sites,and the maximum was in Yangling located in Wei River Agro-ecological Region,while the minimum was in Yulin situated in the Windy and Sandy Region along the Great Wall.The deposition rate of NH4+-N was 3.10 kg·hm-2 in Yulin,3.66 kg·hm-2 in Luoshuan,8.60 kg·hm-2 in Xi'an,9.14 kg·hm-2 in Yangling,9.96 kg·hm-2 in Ankang,while the NO3--N rate were 5.15,7.54,6.29,6.98 and 5.66 kg· hm-2 respectively.The main reason to cause the difference of TIN amount was the different deposition amount of NH4+-N.Wet nitrogen deposition rate ranged from 6.57 to 14.43 kg·hm-2 and dry nitrogen deposition rate varied from 1.19 to 2.74 kg·hm-2.Both of them showed time variability.In summer and autumn,wet nitrogen deposition was higher than that in winter and spring because of the rainfall,whereas dry nitrogen deposition had opposite trend.This could be caused by the washing action of rainfall and greater amount of dust in winter and spring.