识别区域氮磷流失综合风险分布状况并对氮磷流失进行综合调控是控制非点源污染的有效措施.但传统的研究往往局限于氮或磷流失风险的单独评估和调控,以密云水库沿湖集约化农区东庄小流域为例,应用氮指数、磷指数及氮磷综合指数法,对区域氮磷流失风险进行综合评价.结果表明:流域氮、磷流失风险总体上较小,80％以上的区域均处于氮、磷流失的无风险或低风险区,但氮、磷流失的空间分布存在较大差异.其中氮流失的高度风险区集中在山地中土壤侵蚀指数较大的果园;而磷流失的高风险区域主要分布在河流沿岸的农业用地.氮磷综合风险指数显示,93.1％的区域处于无风险和低风险区,中度以上风险区占总面积的6.9％,主要集中在流域中部有着较高的肥料施用、地势陡峭且处在河流沿岸的农业用地或山地中.单独考虑氮指数或磷指数都难以反映区域氮磷流失的综合风险状况,容易忽略磷指数高氮指数低、氮指数高和磷指数低以及氮、磷风险在中等的区域.因此,在氮、磷流失风险评估基础上,进行氮磷流失风险的综合评价,可为氮磷流失的综合调控提供指导.%Identifying the integrated risk of nitrogen and phosphorus loss is essential for applying integrated management strategies to control the non-point source pollution effectively. However, most research focused on nitrogen or phosphorus risk assessment and management only. In this paper, with the case study in Dongzhuang watershed of Miyun reservoir, the nitrogen and phosphorus index, and integrated index were used to assessment the risk of the nitrogen and phosphorus loss at the intensively cultivated lakeshore region. The results showed, more than 80% of the research region was no risk in nitrogen loss and low risk phosphorus risk respectively, and the spatial distribution nitrogen and phosphorus losses were quite different, that the region with high risk of nitrogen loss were mainly the orchard at highland where had greater value of soil erosion index, but the region with high risk of phosphorus loss were mainly agricultural land along the river. The integrated nitrogen and phosphorus risk index, on the other hand, showed that 93.1% of the watershed was no risk and low risk in nitrogen and phosphorus loss, and 6.9% of the watershed, which was mainly agricultural land or land on the mountain with higher fertilizer input, steeper topography, and closing to river, had medium and high risk of nitrogen and phosphorus loss. It was indicated neither nitrogen or phosphorus index can reflect the integrated risk of regional nitrogen and phosphorus loss as the area with high value of P index but low value of nitrogen or with high value of nitrogen index but low value of phosphorus index or with both medium nitrogen and phosphorus index would be ignored. Therefore, an additional integrated the assessment of nitrogen and phosphorus loss risk was essential for making integrated management strategies for the effective control of non-point source pollution.
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