Evaluating and Clustering Analysis of Non-point Source Pollution in Chongqing Three Gorges Reservoir Region

Point and non-point source pollution are the main pollutant source in the Chongqing Three Gorges Reservoir Region,with the latter accounting for 77.85% of the total loadings.Non-point source pollution which generally occurred over an intermittent period from sporadic sources and closely correlated with climatic events is the main pollution source in Chongqing Three Gorges Reservoir region.On the basis of data in 2000,the non-point source pollution is evaluated by using the method of equivalent pollution loading,including rural domestic waste,solid waste,fertilizer runoff,pesticide runoff,poultry and livestock farm,soil erosion,surface flow of city and so on in Chongqing Three Gorges Reservoir region.The 40 administrative districts in Chongqing Three Gorges Reservoir region are divided into 8 areas according to the results of cluster analysis and equivalent pollution loadings.The main nutrients of non-point source pollution were total phosphorus,total nitrogen,ammonia nitrogen,chemical oxygen consumption etc,among which total phosphorus and total nitrogen amounted to 96.4% loadings.The main pollution sources were fertilizer runoff,soil erosion,poultry,livestock farm,rural domestic waste,pesticide runoff,solid waste and surface flow of city etc,among which loadings from fertilizer runoff,soil erosion,poultry and livestock farm accounted for 95.2%.The sum of mean evaluation indexes in each area varied fromⅠto Ⅷ,indicating the differences of non-point source pollution among different areas.In addition,non-point source pollution in each area showed its specific characteristics,which provided scientific basis for controlling non-point source pollution.