南水北调东线典型湖泊流域抗生素时空分异特征及风险辨识

The East-Route of the South-to-North Water Diversion Project is a large-scale infrastructure project that can settle water shortage in north of China. The control of Nansi Lake pollution is a key problem to the East-Route. Due to the vast polluting emissions from breeding industry in the Nansi Lake basin, antibiotics problems are highlighted. On the base of the antibiotics pollution sources and basin characteristics of the Nansi Lake basin, and detection and analysis of antibiotics in the Nansi Lake basin during wet season, normal season, dry season, and diversion period, the temporal and spatial distribution of antibiotics will be discussed by means of cluster analysis, discriminant analysis and principal component analysis. According to the sampling analysis of antibiotics in water/sediment in different period and sites, such as discharge ports, upstream and downstream of gate dam, and inlets and outlets of wetlands, we also select typical rivers to analyze the effect of artificial jamming to antibiotics migration behaviors. Based on related data that effect the risk of antibiotics excavated from antibiotics pollution sources and operation of gate dam and wetland, and the relationships between risk index and risk factors, the risk evaluation indicator system and the method will be established to identify risk level of antibiotics pollution sources and weak links of risk process, and then the environmental risk regulation strategy can be optimized for environmental security of the South-to-North Water Diversion Project.

南水北调东线工程是解决北方地区水资源短缺问题的特大基础设施项目，南四湖流域治污是东线工程成败的关键。南四湖流域养殖业等抗生素使用量大，抗生素问题凸显。本项目调研南四湖流域抗生素污染源及流域特征，通过丰水期、平水期、枯水期和调水期南四湖流域出、入湖河流抗生素等污染物检测分析，运用聚类分析、判别分析、主成分分析等方法，探讨抗生素时空分异特征；选取典型河流，通过抗生素污染源排放口、闸坝上下游、湿地进出口等不同时期水/沉积物采样分析，剖析闸坝调蓄、湿地工程等人为干预对抗生素迁移行为的影响；挖掘抗生素污染源、闸坝湿地运行对流域抗生素风险影响等相关数据，厘清各因素与污染源风险值的关系，构建南四湖流域抗生素污染源风险辨识指标体系，建立抗生素污染源风险等级及风险环节辨识方法，优化流域尺度环境风险调控策略，为南水北调水环境安全保障提供决策支持。

本项目主要以抗生素为研究对象，对南水北调东线南四湖流域主要入湖河流水及沉积物中抗生素时空分异特征进行研究，辨识其环境风险，并探讨该流域污水处理厂、湿地系统等对抗生素迁移的影响。主要研究成果如下：.①南四湖30条主要入湖河流表层水和沉积物中均检出14种抗生素，水和沉积物中抗生素浓度范围分别为nd-693.69 ng•L-1和nd-207.241 μg•kg-1。其时空分布规律为：南四湖30条入湖河流表层水和沉积物抗生素总浓度均表现出枯水期>平水期>丰水期，上级湖>下级湖。.②基于风险熵值法计算得出：从时间上看，枯水期抗生素风险>平水期抗生素风险>丰水期抗生素风险，从不同营养级看，抗生素风险从大到小依次为algae>plant> invertebrate>fish。.③南四湖流域典型河流小沙河表层水和沉积物中均检出23种抗生素，水中抗生素浓度范围为nd-517.316 ng•L-1，沉积物中抗生素浓度范围为nd-496.047 μg•kg-1；小沙河表层水中抗生素总浓度呈现枯水期>丰水期>平水期；沉积物中抗生素总浓度呈现出丰水期>平水期>枯水期。.④南四湖6个典型湿地的水中诺氟沙星（NOR）和磺胺喹恶啉（SQL）浓度最高，总浓度分别为251.080 ng•L-1和77.352 ng•L-1；沉积物中氧氟沙星（OFL）和诺氟沙星（NOR）浓度最高，总浓度分别为805.768 μg•kg-1和427.959 μg•kg-1。.⑤小沙河湿地段丰水期对抗生素的去除率（88.26%）远高于平水期（27.76%）和枯水期（27.76%）；丰水期6个湿地系统对水中抗生素的去除率分别为88.26%（小沙河湿地）、86.85%（墨子湿地）、80.71%（微山湖湿地）、44.69%（二级坝湿地）、81.23%（郭河湿地）、55.20%（滨湖湿地）。.⑥南四湖30条主要入湖河流表层水通过主成分分析-多元线性回归方程（PCA-MLR）估算得出枯水期主要污染源为B（济宁）、C（枣庄）和D（徐州）共源：66.8%；平水期主要污染源为A（菏泽）源：78.5%；丰水期主要污染源为B源：59.6%。.⑦小沙河表层水通过PCA-MLR模型估算得出枯水期主要污染源为S（污水厂）和L（养殖场）共源：50.7%；平水期主要污染源为：S和L共源：58%；丰水期主要污染源为：S和L共源：52.4%。