城市湖泊流域面源污染的源-汇效应研究——以武汉市东湖为例

The source-sink effect between urban diffuse pollution and Lake watershed: A case study in East Lake of Wuhan

随着城市点源污染控制不断完善,城市面源污染已成为危害中国城市水体的重要污染源。由城市土地利用变化引起的地表径流污染是导致湖泊水质恶化和富营养化的主要因素,加强面源污染的源-汇效应研究是控制、管理流域污染的重要途径之一。研究选取中国最大的城市湖泊武汉市东湖为研究对象,运用遥感和GIS技术,进行流域划分和地类解译,建立土地利用基础数据库,后对水质统计数据进行定量化处理,通过建立了地类——湖泊水质关系模型,科学地分析了用地与水质的关系,并对城市湖泊水质的季节动态、影响因素进行了初步探索。研究结果表明土地利用和气候变化对流域内湖泊水质的影响显著。其中,农田和建设用地是城市湖泊面源污染的主要来源,绿地和坑塘水面能够有效的截流、吸收污染物,起到保护湖泊水质的作用;受降水、温度等气候因子的影响,湖泊水质状态呈现季节性波动。研究选取东湖为研究对象,研究面源污染的源-汇效应,具有代表性,对于更好保护城市湖泊,合理利用湖泊资源提供了理论依据。

Although urban point source pollution control has been strengthened in recent years, urban diffuse pollution has become a major source impeding sustainable water development in China. Surface runoff pollution caused by land use change in urban areas is one of the fatal factors causing eutrophication and the deterioration of water environment. As a result, research on source-sink effect would be of significance on pollution control and management, especially in the watershed. We take East Lake in Wuhan as the study area in our research. After the watershed division and land use classification from ETM remotely sensed images, we establish a land-use database thorugh GIS. Then a regression model is set up in an attempt to explore the relationship between lake water quality and different land use types. Analysis is also made on the seasonal dynamics and the influential factor of lake water quality. The results show that land use and climate change exert great influencs on water quality in a watershed. Farmland and construction land are the main source of lake diffuse pollution. Meanwhile green fields and pond water can obstruct and absorb pollutants effectively, which plays a key role in protecting the environment of lakes. Due to physical factors such as precipitation and temperature, water quality presents obvious seasonal fluctuations. Through research on east lake, we discuss source-sink effect of diffuse pollution, which would be meaningful for the protection and rational utilization of lake resource.