丹江口水库是南水北调中线工程的水源地,也是我国规模最大的饮用水水源保护区,农业面源污染是影响其水质的首要因素,合理估算其水源区农业面源污染物的流失量对确保该水库水质有着重大意义.在实地调研的基础上,采用分形理论估算了丹江口水库水源区河南省所在区域2013年TN、TP的流失量,并与输出系数法的结果进行比较.结果表明:两种方法都显示该区域污染物的流失以氮为主,其中分形理论结果显示TN流失量是TP流失量的7.156倍(输出系数法为6.773);禽畜养殖产生的污染物流失量最多,占总流失量的69.93％(输出系数法为70.28％),农田化肥产生的污染物流失量占总流失量的21.99％(输出系数法为21.74％);无论是TN、TP的流失总量,还是二者的总流失量,两种算法配对t检验的P值(双侧)均小于0.05,具有统计学意义;分形方法考虑了下垫面对污染物流失的影响,而输出系数法只是简单地将各区域的流失率平均化,故分形方法所得结果比输出系数法更为可靠.研究显示,运用分形方法来研究区域面源污染是适宜的,同时也拓展了流域尺度面源污染的计算方法.%The Danjiangkou Reservoir is the water source of the South-to-North Water Transfer Project,and is also the largest protected zone for drinking water sources in China.Agricultural non-point source pollution is the primary factor that negatively affects its water quality.Therefore,it is of great importance to reasonably estimate the pollution load of agricultural non-point sources in the region to ensure the reservoir water quality.Fractal theory was applied to estimate total nitrogen (TN) and total phosphorus (TP) load in the Danjiangkou Reservoir catchment areas in Henan Province in 2013 by onsite investigation.The results from the fractal theory model were compared to those from the coefficient method.Both methods showed that nitrogen dominates the pollution load in the area,with TN load being 7.156 (6.773 by output coefficient method)times that of TP.The pollution load from livestock farming was the most important contributor,accounting for 69.93％ (70.28％ by output coefficient method)of the total;the.pollution load from farmland accounted for 21.99％ (21.74％ by output coefficient method).The P values (double side)from the paired t-test by the two algorithms were less than 0.05 regardless of the total load of TN,TP,or total load of the two,which indicated the analysis is statistically significant.The results of the fractal method,which considered the effects of the underlying surface,were better than those of the output coefficient method,which simply averaged the loss rate of the same pollutant from different areas.Thus,it is appropriate to use the fractal method to study regional non-point source pollution,but also extends the calculation method of non-point source pollution in watershed scale.
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