三峡库区面源污染现状与对策研究

STATUS OF NON-POINT SOURCE POLLUTION IN THE THREE GORGES AREA WITH DISCUSSION ON THE COUNTERMEASURES

三峡库区生态环境脆弱,坡耕地垂直分布明显,耕地利用方式不合理,库区耕地环境质量较差,水土流失严重。库区沿江工厂星落棋布,落后的生产工艺和小规模生产,使大量废水没经处理直接排放到库区各大河流。虽然目前长江流域水体的自净作用能将污水稀释,但随着三峡大坝的正式蓄水,部分区域水体污染将不可避免。通过对库区部分区域水体近几年的连续监测,水体总P、非离子氨、CODcr等指标有恶化趋势。库区土壤重金属监测结果表明,土壤重金属Cd、As含量明显增加,并且远大于当地土壤背景值。库区农畜产品蔬菜、茶叶、鱼Pb、Cd超标较严重。土壤N、P流失率较高。有效防止库区面源污染的对策一方面是控制工业点源、线源污染造成的面源污染,另一方面是控制农业自身造成的面源污染。主要措施有:加强库区环境管理和环保宣传力度;建立沿江生物隔离带;加强土地管理,加大农业工程投入,合理利用土地;大力提倡水土保持耕作法;扩大森林覆盖率,建立坡地立体复合农业生态系统;建立面源污染预警系统。

The distribution of farmland and sloping field is obviously vertical in the Three Gorges Area,and the utilization of the farmland and sloping field is nonrational.The environmental quality of the farmland has been bad with soil erosion being very serious.The factories in this region are scattered distributed in the area,because of the lower level of tchecnology and lower scale of production.A lot of untreated waste water has been discharged into the river system,although the river may have some self-purification ability.In some parts of the area,the continuous monitoring of the water revealed that all N,non-ion ammonia,CODcr have become worse.The monitoring of heavy metals in soil demonstrated the contents of Cd,as were much higher than the background.The Pb,Cd in vegetable,tea,fish and other animal products exceed the standard.The running-away of ratio of N,P in soil was high.The countermeasures for controlling the non-point source pollution were proposed,including the control of point source and line source,together with agricultural pollution.