城市典型湖泊水-沉积物系统多环芳烃迁移及归趋研究

With the rapid development of urbanization, the hot concerns on persistent organic pollutants in urban ecosystem always focus on the variety of their environmental behaviors and the responding mechanism to urbanization. The Dianshan Lake, as an important drinking water source district in Shanghai, receives polycyclic aromatic hydrocarbons (PAHs) via atmospheric dry/wet deposition, sewage discharge and surface runoff, causing more and more serious pollution problem. However, few study reported the multi-media distribution characteristic, transfer mechanism and fate model in the water-sediment system of the Dianshan Lake under the driving of urbanization. Therefore, this study will deeply reveal the occurrence characteristic, transfer process and key impacting factors of PAHs in the truly dissolved phase - colloid - suspended particle matter - sediment system, analyze the temporal variation rule of PAHs contents in the lake sediment cores, and discriminate the historical variation of input routes and pollution sources by means of compound-specific carbon isotope technology. All the aims are in order to explore the coupling relationship between urbanization development and lake cycle of PAHs from the perspective of space-time. Based on the aforementioned results, this study will further construct a level IV fugacity model to simulate the seasonal variation of multi-media transfer of PAHs for the convenience of forecasting and early warning, providing theoretical support and scientific basis for the security of water quality and aquatic product.

伴随城市化的快速发展，城市系统内持久性有机污染物的环境行为变化及其对城市化响应机制研究一直是人们关注的焦点。当前上海重要的饮用水源地-淀山湖在大气沉降、污水排放和地表径流等混合污染源输入下多环芳烃（PAHs）污染问题日益突出，然而对城市化驱动下淀山湖水-沉积物系统中PAHs多介质分布特征、迁移机制及归趋模拟的研究还很不足。因此，本项目拟从系统层面深入揭示淀山湖PAHs在真溶解态-胶体-悬浮颗粒物-沉积物中的赋存特征、迁移分配过程及关键影响因子，同时分析湖泊沉积柱中PAHs含量的时间演变规律，并集成有机单体稳定碳同位素示踪技术辨析湖泊PAHs输入路径及来源的历史变化，从时空角度探讨城市化发展与淀山湖PAHs迁移循环的耦合关系。在上述基础上，构建四级逸度模型来模拟PAHs多介质迁移的季节性变化以进行预测预警，为保证淀山湖水质和水产品安全提供理论支持和科学依据。

快速城市化发展所带来的土地利用/土地覆被变化（LUCC）已经极大改变了城市系统内污染物的物质循环规律和模式。上海环淀山湖（饮用水源地）流域作为新兴的城市化区域，正面临日益突出的PAHs污染问题。因此，本研究重点调查了淀山湖多相系统中PAHs的迁移循环过程，深入探讨了溶解水-悬浮颗粒物-沉积物-生物系统中PAHs的时空赋存特征、分配机制和关键影响因子，揭示了城市LUCC与整个上海湖泊沉积物中PAHs含量的耦合关系，比较并分析了不同城市化区域湖泊沉积柱中PAHs历史演变和源差异，同时构建了QWASI模型实现了对PAHs多介质季节变化的预测预警。主要研究结果如下：（1）系统阐明了PAHs在淀山湖溶解水相、悬浮颗粒相、表层沉积相、水生植物、优势鱼种等多个环境介质中的含量分布特征和时空变化规律，并评估了PAHs的生态和人体健康风险；（2）联合正定矩阵因子分析（PMF）模型和土地利用回归（LUR）模型，辨析了遍布上海的33个湖泊表层沉积物中PAHs富集规律和潜在来源，模拟预测了LUCC对PAHs沉积归趋的影响；（3）重建并比较了新兴和早期城市化区域湖泊沉积柱中PAHs和EC的污染累积史，构建了扩展的随机影响模型，定量评价了城市化发展过程中社会经济因子变动对湖泊PAHs和EC历史累积的影响；（4）构建了PAHs多介质逸度模型，模拟了淀山湖大气、水体和沉积物三大主相中PAHs的季节性变化，通过模型校正、不确定性分析和灵敏度分析等手段确定了模型有效性及关键影响因子。项目成果将为未来环淀山湖流域及其他正在快速发展中的城市区域污染防控和管理提供科学依据。