查干湖汇水区面源污染风险识别及管控

面源污染是我国流域面临的主要水环境问题，为了识别面源污染高风险区和潜在风险路径，实现流域水环境保护，以查干湖水质目标为约束条件，构建4类关键“源”景观.选取高程、坡度、土地利用类型、污染强度、距居民点距离、距公路距离、距铁路距离、距水体距离等8个评价因子构建阻力面，对查干湖汇水区面源污染风险区和风险路径进行识别，提出管控分区和治理措施.结果表明:①查干湖汇水区关键“源”景观有4类，分别为面源污染单位面积高负荷区、坡度>3°区域、污染传输通道和临湖区域，面积共126.33 km2.②查干湖汇水区面源污染高风险区即面源污染重点管控区，占汇水区总面积的27.10%，主要位于乾安灌区有字泡区域、查干湖及周边泡沼沿岸.区内现有耕地不再增加，同时对坡度较大的区域退耕还湿、退耕还草，并设置污染降解设施.③查干湖汇水区面源污染较高风险区即面源污染一般管控区，占汇水区总面积的20.23%.该区鼓励开展有机农业，发展生态旅游.④查干湖北岸和东南岸、库里泡周边设置一定宽度的植被缓冲带，汇水区设置生态降解渠道333.41 km，生态湿地节点9个.研究显示，污染排放强度是查干湖汇水区面源污染风险的主要威胁因素，需要重点加强查干湖汇水区乾安灌区有字泡、湖区北岸及东南岸的面源污染管控. 

Risk Identification and Control of Non-Point Sources Pollution in Chagan Lake Catchment Area

In order to identify the high risk areas and potential risk paths of non-point source pollution of Chagan Lake, four kinds of key source landscapes were constructed with the water quality target as the constraints. Resistance surface was built by eight assessment factors, including altitude, slope, land use, pollution intensity, and distance from residential land, road, railway and water area. The risk areas and risk paths of non-point source pollution were identified. The control measures were constructed. Our results showed that: (1) There were four types of key 'source' landscapes in Chagan Lake catchment area, which were the high load area of non-point source pollution, the area with gradient > 3°, the pollution transmission channel and the lakeside landscape, covering an area of 126.33 km2. (2) High risk area of non-point source pollution is the key control area, accounting for 27.10% of the total catchment area, located in Youzi Lake of Qian'an irrigation area, the lakefront areas and surrounding lake areas. The control measures in this area including: the existing cultivated land should increased, the area with higher slope should returned back to wetland or pasture, and pollution degradation facilities should be built. (3) The relatively high risk area of non-point source pollution is the general control area, accounting for 20.23% of the total catchment area. The organic agriculture and ecotourism in this area were encouraged. (4) Vegetation buffer zones should be constructed on the north bank and southeast bank of Chagan Lake, and on both sides of Kuli Lake. 333.41 km ecological degradation channels and 9 ecological wetland nodes in the catchment area should be planned. The results show that the pollution emission intensity is the main threat to non-point source pollution. It is necessary to strengthen the control of Youzi Lake of Qian'an irrigation area on the north bank and southeast bank of Chagan Lake.