Farmland Non-point Source Pollution Load Estimation And Risk Assessment In Chaohu Lake Basin

Agricultural non-point source pollution(ANSP)has the characteristics of being extensive and lagging,and it is difficult to obtain data and be governed.By assessing the risk of TN and TP pollution in farmland via the TN and TP index method,the grade of pollution was divided and the key source areas for pollution in Chaohu Lake basin were identified.According to the risk level,specific measures ware proposed in order to provide references for the environmental protection decision-making and governance departments of the Chaohu Lake Basin to reduce the cost of ANSP treatment effectively.The main research results of this paper were as follows:(1)The result of Bibliometrical Analysis shows that the first three directions with highest degree of concern and large amount of articles are governance,models and current status.Relative to other hotspot regions in the country,the research efforts in Chaohu Lake basin should be increased.The hotspots were found by plotting term-co-occurrence graph with R language.The literature analysis shows that persuasiveness of governance and the innovation of models need to be further enhanced;the combination of models and 3 S is the trend;the determination of ecological compensation standards is a difficult problem;risk assessment is an effective way of governance.(2)Based on GIS and pollutants coefficients,a sub-basin load estimation method was proposed.The results indicate that the TN load range of Chaohu sub-basin was 0?4290983.5 kg and the TP load range was 0?893484 kg.The areas with higher load in Chaohu Lake basin are mainly distributed in Nanfei River basin,the downstream of the Hangbu-Fengle River,the downstream of the Baishitian River and part of the Yuxi River sub-basin.(3)The results of the risk assessment in Chaohu Lake basin shows that the areas with high risk of TN and TP loss of farmland in Chaohu were mainly distributed in Lujiang County,the south of Wuwei County,i.e.the upstream of Baishitian River,He County,i.e.part of Yuxi River sub-basin;the areas with moderate risk were mainly distributed in Hefei City,i.e.part of Nanfei River sub-basin,Chaohu City,Hanshan County,the north of Lujiang County and downstream of Hangbu-Fengle River.The areas with low risk were mainly distributed in Feixi County,i.e.Shiwuli River.Finally the targeted preventionand control measures were proposed base on this.