浅水湖泊滩地淹露交替区底泥典型抗生素污染释放机理研究

The mechanism study of contaminant release from sediments in the submerging-emerging cycling region of shallow lake beach is still unsubstantial, especially under the effect of different hydrodynamic disturbances. In this project, the norfloxacin (NOR) release dynamics from sediment in the alternately submerged-emerged region of shallow lake beach, is planned to be revealed. The driving mechanism of hydrodynamic characteristics, such as water-sediment interface shear stress, turbulence intensity, mixing intensity, etc., on NOR release from the wetting-drying cycling sediments will be focused. The key dynamic factor influencing the sediment release will be clarified, and the pressure-response relationships between the key factors and NOR emission flux will be built. The critical hydraulic condition corresponding to the maximum NOR concentration in overlying water under different submerged-emerged cycles pattern will be captured, of which the quantitative criterion will be identified. The dynamic model of NOR release from sediment in alternately submerged-emerged region of shallow lake beach will be established. The research achievements will lay the scientific foundations for the revelation of release laws of antibiotics pollutants from lake beach sediment under submerged-emerged cycles, and the control of these emerging contaminants in lake environment.

目前针对浅水湖泊滩地淹露交替区域底泥，在湖滩往复振荡水流扰动下的污染释放研究仍较为欠缺。本次申请的项目旨在揭示浅水湖泊滩地淹露交替区底泥典型抗生素污染物－诺氟沙星污染释放机理，着重探究滩地振荡水流动力要素如沉积物－上覆水界面剪切力、脉动强度、掺混强度等对淹漫覆盖－退水出露循环底泥NOR释放的胁迫行为与作用机制；厘清主导淹露交替底泥NOR释放的关键特征因子，并揭示其对污染物净释放通量的压力－响应关系；捕捉沉积物在不同干湿循环模式条件下上层水体中最大NOR浓度所对应的临界水流运动状态，提出量化的临界水力判据；构建多因子复合驱动的浅水湖泊滩地淹露交替区底泥NOR内源释放模块，为浅水湖泊抗生素污染内源释放机理的揭示以及将来的防控铺垫理论基石。

目前针对浅水湖泊滩地淹露交替区域底泥，在湖滩往复振荡水流扰动下的污染释放研究仍较为欠缺。本项目选取平原河网地区典型浅水湖泊江苏省骆马湖为研究对象，开展了浅水湖泊诺氟沙星(NOR)等典型喹诺酮抗生素(QNs)原观调查，在此基础上构建了淹露循环底泥污染物释放动水模型水槽试验系统，针对骆马湖滩地不同干湿交替行为底泥，进行不同淹露循环和全浸没静水条件下沉积物NOR释放过程的模拟，揭示湖泊滩地底泥NOR的污染释放机理。本项目取得的重要结果为：(1)调查了骆马湖水体、沉积物以及水生动物等多相介质中NOR等典型QNs的赋存水平，研究了目标污染物在调水期和非调水期的分布特征，并评估对人体的健康风险；(2)构建了淹露循环底泥污染物释放动水模型水槽试验系统，针对湖泊滩地不同高程底泥，探明了滩地底泥不同干湿循环模式、动力要素对NOR释放净通量的影响行为与作用机制；(3)厘清了主导干湿循环模式底泥NOR释放的关键动力特征因子，揭示其对沉积物污染物净释放通量的压力－响应关系，探寻了底泥不同干湿循环模式条件下NOR释放量最大对应的上覆水流状态；(4)针对浅水湖泊滩地淹露交替区域，构建了多因子复合驱动的非稳态底泥NOR内源释放模块。项目研究为完善湖泊内源释放理论，准确把控湖泊内源污染释放量，全面揭示抗生素污染物在浅水湖泊天然环境中归趋行为与将来的防控铺垫理论基石，具有重要的学术意义与工程应用价值。