Review on non-point source pollution in Miyun Reservoir

Miyun Reservoir is a unique surface water source of table-water for Beijing City, where most pollutants contaminating the reservoir are from non-point sources (NPS). This paper reviews a number of recent studies on NPS pollution in the watershed from the pollutant load and distribution, evaluation and prediction; and summarizes the factors and mechanisms of pollution as well as pollution control and management strategies. NPS pollution mainly comes from soil erosion, irrational chemicals utilization, livestock and poultry wastes, and byproducts of aquaculture. About 70% COD, 70% BOD₅, 90% NH₃-N, 70% TN and 90% TP in the reservoir water come from NPS pollution; but NPS pollutant load differs with precipitation, land use type, chemical load, degree of crop cover, etc. Along with the prediction of the trend of change of NPS pollutants, the findings and limitations of the studies are discussed and prospective pollution control, water quality protection and future research directions proposed. It is suggested that further studies should be conducted on agricultural NPS pollution, the process of pollutant movement, the change mechanism of pollution concentration and their management strategies.