三峡库区典型小流域非点源氮磷污染的来源与负荷

选择三峡库区典型小流域——忠县石宝镇石盘丘小流域,通过对其2007—2009年主要土地利用类型降雨径流中氮磷流失形态与含量进行连续监测,研究三峡库区非点源氮磷污染的来源与负荷。结果表明,三峡库区非点源氮磷污染的来源主要是居民点、柑橘果园和坡耕地,三者累计贡献了76%以上的小流域氮磷污染负荷,因此非点源污染控制的关键是拦截居民点、柑橘果园和坡耕地的暴雨径流。水稻田作为三峡库区主要的农耕地,对径流、泥沙和养分具有显著的截留和净化作用,对来自居民点的氮磷去除效率都在56%~98%之间,因此水稻田合理管理与化肥高效利用是三峡库区非点源污染负荷减控的重要途径。

Source and Load of Non-Point Source Nitrous and Phosphorus Pollution of Typical Small Watersheds in the Three Gorges Reservoir Area

The paper selects Shipanqiu Small Watershed,an typical small watershed situated at Shibao Township of Zhongxian County in the Three Gorges Reservoir area and studies the source and load of non-point source nitrous and phosphorus pollution of the reservoir area through continuous monitoring on the forms and content of nitrous and phosphorus loss in rainfall runoff of main land use types during the period from 2007 to 2009.The outcomes show that the source of non-point source nitrous and phosphorus pollution of the reservoir area mainly comes from residential areas,citrus orchards and sloped lands.The nitrous and phosphorus pollution load of the three areas makes up more than 76% of that of the small watersheds.Thus,the key point of non-point source pollution control is to intercept storm runoff from residential areas,citrus orchards and sloped lands.Paddy fields are the main cultivated land of the reservoir area,having the functions of interception and purification for runoff,sediment and nutrient of small watersheds and the efficiency of de-nitrogen and de-phosphorus from residential area is between 56% and 98%.Thus,the rational management and effective utilization of fertilizer of paddy fields are the main important ways for load reduction of non-point source pollution of the reservoir area.