陕西省不同生态区大气氮沉降量的初步估算

2008年,对陕西省4个不同生态区5个监测点的干湿沉降输氮量进行为期1年的观测研究,旨在对不同生态区大气氮沉降量进行初步估算。结果表明,2008年各生态区总无机氮(TIN)沉降量在8.25～16.12kg·hm-2之间,其中以地处长城沿线风沙草原生态区的榆林地区最小,渭河谷地农业生态区的杨凌地区最大。榆林、洛川、西安、杨凌以及安康地区NH4+-N沉降量分别为3.10、3.66、8.60、9.14和9.96kg·hm-2,NO3--N沉降量分别为5.15、7.54、6.29、6.98和5.66kg·hm-2,NH4+-N沉降量的不同是造成TIN沉降量之间差异的主要原因。各生态区湿沉降输氮量为6.57～14.43kg·hm-2,干沉降输氮量为1.19～2.74kg·hm-2,均显示出一定的时间变异性。受降雨量影响,湿沉降量在降雨量大的夏秋季较高,降雨量小的冬春季较低;干沉降量则与之相反,可能是由于雨水的冲刷作用和冬春季节扬尘天气较多引起的。

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 NH+4-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 NO-3-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 NH_4-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.