Abstract: A case study of Xinqi Village,Wukang Town,Deqing County of Zhejiang Province was carried out,through investigation of pollution sources and water environment for analysis of sources and characteristics of the rural non-point source pollution(NPSP) in small watersheds in the river-net plain regions and estimation of load and proportion of different non-point source pollutions in the study area.Results show that aquaculture,rural domestic sewage and crop farming are the main sources of non-point source pollution in the study area.The discharge of nitrogen and phosphorus pollutants from aquaculture accounts for 31.73% and 21.59%,respectively,of the total pollution load;rural domestic sewage is the major contributor to the total phosphorus pollution load,accounting for 39.48% of the total;excessive application of N and P fertilizers in crop farming contributes 27.69% and 28.53%,respectively,to the total N and P pollution loads;and livestock and poultry rearing contributes the lowest proportion,being only 10.75% and 10.40%,respectively,to the total N and P pollution load.The use of large quantities of livestock and poultry manure in crop farming for soil building transfers the portion of pollution load from livestock and poultry breeding industry to crop farming.The farmlands cultivated with watermelon,winter jujube and grape are the highest in phosphorus pollution load per unit area;the grain crop fields the lowest,and the strawberry fields the lowest in nitrogen pollution load per unit area.It is,therefore,recommended that the focal point of the control of agricultural non-point source pollution be shifted from traditional grain crop cultivation regions to high-input intensive farming areas and reasonable engineering and technical measures be adopted to reduce the discharge of wastewater from aquaculture and rural domestic sewage.

Key words: north Zhejiang, small watershed in river-net plain region, rural non-point source pollution, nitrogen, phosphorus