| In order to fully understand the pollution sources and pollutants of small watershed in Chaohu Jiyu river,this research adopts the soil erosion model?RUSLE?and runoff curve model?SCS-CN?,combined with the GIS space analysis function,the basin non-point source pollution in detail the type,quantity and distribution characteristics of the investigation and analysis of four types of main pollution sources and estimation of nitrogen and phosphorus nutrient loss,quantitative reveal watershed spatial distribution characteristics of nitrogen and phosphorus nutrient losses,such as through equivalent pollution load and equivalent standard pollution index methods to evaluate the major pollution sources,and put forward the related policy pollution prevention advice,to work of soil and water conservation and ecological environment recovery and protection in this area to provide theoretical basis and scientific reference,to explore suitable for small watershed non-point source pollution of quantitative research methods,the results show that:Agricultural non-point source pollution is caused by Jiyu river basin of non-point source pollution type,the main pollution of COD in circulation of 275.186 t/a,TN loss of104.041 t/a,TP loss of 9.692 t/a,total amount of pollutant loss of 388.919 t/a.Soil and water loss is the most main watershed non-point source pollution caused by the carrier,in 2016,the total amount of soil erosion in Jiyu river is 14979 t·a-1,the range of89.76%of the basin was microscopically eroded,less than 11 percent of the erosion was minor or above,the average soil erosion intensity is 197.40 t·km-2·a-1;The soil nitrogen and phosphorus loss caused by soil erosion were 78.461 t/a and 26.196 t/a,the dissolved nitrogen and phosphorus loss accounted for 72.39%and 57.92%respectively,in the area of gently topography,rainfall and surface runoff carries is the main form of soil nutrient loss.In 2016,the total amount of pollutant loss in the Jiyu river basin was 493.576 tons,and the loss of COD,TN and TP accounted for 55.75%,36.98%and 7.27%respectively.The amount of COD,TN and TP respectively accounted for 3.66%,48.58%and 47.76%respectively.The pollution load rate of TN and TP is more than 90%,which is the main pollutant in the basin.In 2016,the pollution sources of rural domestic living,soil and water loss,animals'feces and chemical fertilizers pollution sources in the Jiyu river basin accounted for50.92%,21.2%,17.76%and 10.12%respectively.The equivalent standard discharged amount of soil and water loss,rural domestic living sources,chemical fertilizer sources,animals'feces sources,accounted for 55.75%,17.16%,14.72%and 12.38%respectively.The soil nitrogen and phosphorus nutrient loss caused by soil erosion is the key pollution source of water environment degradation.The source of agricultural source pollution is the main source of pollution in the basin. |
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