妫水河流域农耕区非点源磷污染危险性评价与关键源区识别

农业非点源磷污染是我国农村水环境面临的严重污染问题,由于非点源污染治理难度大,所以识别流域内磷流失的关键源区成为非点源污染控制的重点.本文在Hughes等的流域尺度磷分级方案的基础上,提出了修正的流域尺度磷分级方案,并运用到官厅水库上游妫水河农耕区的磷元素危险性评价.提出的新方案中包括8个评价因子,每个因子都有3个磷流失危险性等级,各评价因子均确定了定量分析方法.结果表明,从作物的人为管理角度来看,蔬菜地的磷肥管理方式最不合理,发生磷流失的可能性最高.研究区内大部分区域的土壤有效磷含量较高,但土壤侵蚀程度较小.评价结果图显示,研究区内磷流失危险性低的区域所占面积较小.根据评价结果,确定了研究区内磷流失的关键源区,分析了其空间分布特点,并提出了相应的控制管理对策.研究表明修正的流域尺度磷分级方案具有较高的可操作性和实用性.

Identification of Critical Area of Phosphorus Loss in Agricultural Areas of Guishui River Watershed by Phosphorus Loss Risk Assessment

Agricultural non-point sources pollution is one of severe problems for water environment of agricultural areas in China.Because of the big difficulties,identifying the critical source areas for phosphorus loss becomes the focal point of the non-point sources pollution control.A modified catchment scale phosphorus ranking scheme was developed for agricultural areas in Guishui River watershed.The new scheme included eight assessment factors,which had three phosphorus loss risk ranks respectively and selected quantitative analysis method.The result shows that the phosphorus fertilizer management of the vegetable fields is the most unfit method and has high phosphorus loss probabilities.Most study areas have high soil available phosphorus content and low soil erosion degree.The figure of the assessment result shows that the areas that are categorized as "low" phosphorus loss risk are small.Based on the figure of the result,the critical source areas were confirmed and the management strategies were brought forward according to the analysis on the distribute characteristics of the critical source areas.The result shows that the modified catchment scale phosphorus ranking scheme has operability and practicability to a certain extent.