泾河流域农业非点源污染解析

Analysis of Agricultural Non-Point Source Pollution in the Jinghe River Basin

为研究泾河流域农业非点源污染状况及空间分布特点,采用输出系数模型估算泾河流域2017年农业非点源污染TN、TP、NH_3-N和COD产生量,再利用等标污染负荷法和聚类分析进行评价,结合ArcGIS软件得到污染物年产生量空间分布图,最后利用径流分割法进行验证。结果表明:2017年泾河流域TN、TP、NH_3-N、COD输出负荷分别为124 857.49、5 023.19、26 655.73、258 961.52 t,各污染物空间分布较一致;从污染物角度分析,首要污染物是TN,从污染源角度分析,TN、TP、NH_3-N等标污染负荷中土地利用贡献率最大,COD等标污染负荷中最大的污染源是畜禽养殖,等标污染负荷从西北至东南呈递减趋势,最大值均出现在环县;采用聚类分析法将泾河流域32个县(区)划分为6个污染等级,流域中上游区域污染水平最高,同时提出3种污染防治对策;运用径流分割法对模拟结果进行合理性分析,COD和NH_3-N的相对误差为3.07%、26.87%,具有一定合理性。

In order to study the non-point source pollution status and spatial distribution characteristics of the Jinghe River Basin,the output coefficient model was used to estimate the pollution yield of agricultural non-point source pollution in the Jinghe River Basin in 2017,and then the equivalent pollution load was used.The method and cluster analysis were used to evaluate the spatial distribution map in combination with ArcGIS software.Finally,the runoff segmentation method was used for verification.The results show that a)the output loads of TN,TP,NH3-N and COD in the Jinghe River Basin in 2017 are 124857.49 t,5023.19 t,26655.73 t and 258961.52 t respectively,and the spatial distribution of pollutants is consistent.b)From the perspective of pollutants,the primary pollutant is TN(65.86%).From the perspective of pollution sources,the land use contribution rate of TN,TP and NH3-N is the largest.The largest pollution source of COD and other standard pollution loads are livestock and poultry breeding.The load is decreasing from northwest to southeast,and the maximum pollution load is in Huanxian County.c)Cluster analysis divides 32 counties in Jinghe River Basin into 6 pollution levels,and the pollution level in the upper reaches of the basin is the highest.Three kinds of prevention and control measures are proposed.d)The rationality analysis of the simulation results is carried out by the runoff segmentation method.The relative errors of COD and NH3-N are 3.07% and 26.87%,and the simulation error is in a certain range,which is reasonable.