岗南水库上游流域大气氮干湿沉降研究

Dry and wet deposition of nitrogen in the upstream basin of Gangnan Reservoir

以岗南水库上游流域为研究对象,在岗南水库及其控制流域设置5个采样点位,分析2015年7月至2016年6月流域大气氮素干、湿沉降通量时空分布特征。结果表明,岗南水库流域总氮干、湿沉降通量范围分别为17.7～134.7kg/(km^2·月)和9.9～386.8kg/(km^2·月)。大气干沉降以硝态氮和有机氮为主,春、夏季较高;湿沉降中氮素形态以氨态氮和硝态氮为主,夏季最高,春季次高,秋冬季较低。空间分布上,呈现出由西北向东南不断增加的趋势。利用大气氮素总沉降量、流域面积以及水库水面面积计算得到全流域大气总氮沉降入河负荷量为3 674t/a,直接沉降入库负荷量为105.16t/a。

In this study,we chose five sampling points in Gangnan reservoir basin to monitor nitrogen depositions.We analyzed the spatial and temporal distribution characteristics of dry and wet deposition fluxes of atmospheric nitrogen from July 2015 to June 2016.The results showed that dry and wet deposition fluxes of total nitrogen were 17.7-134.7 kg/(km 2·month)and 9.9-386.8 kg/(km 2·month)respectively.The nitrate and organic nitrogen were the dominant contributors to atmospheric dry deposition flux.Their amount was higher in spring and summer.The nitrogen forms in wet deposition were mainly ammonia nitrogen and nitrate nitrogen,the amount of which was higher in summer and spring and lower in fall and winter.In terms of spatial distribution,there was an increasing trend from the northwest to the southeast.Based on the total amount of atmospheric nitrogen deposition,watershed area,and reservoir surface area,we calculated the total atmospheric nitrogen deposition into river for the whole basin,which was 3 674 t/a.The direct nitrogen deposition into the Gangnan reservoir was 105.16 t/a.