State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
Chemosphere. 2013 Feb;90(8):2288-96. doi: 10.1016/j.chemosphere.2012.10.093. Epub 2012 Nov 30.
Water quality in watersheds is severely impacted by nutrient enrichment as a result of agricultural activities. Understanding hydrological effects on P dynamics can optimize the ecological function of riparian wetlands to reduce nonpoint source pollution. The XiaZhuHu wetlands were selected for field P investigation, and two typical hydrological batch studies of 35 d each (a static column observation simulating the dry season, and a steady-flow flume observation simulating the rainy season) were conducted to understand sediment P dynamics and evaluate capacity of P immobilization. The average equilibrium P concentration of 0.02 mg L(-1) among the 31 sampled sediments was generally lower than the average dissolved reactive P concentrations in the overlying water, indicating an ecological role as a P sink. In static simulation observation, there was a fast-pace sorption process during the first 3d followed by a slower paced process, and the mass of P adsorbed per unit sediment surface (MPAS) reached 0.16 mg cm(-2). The temporal curves of P equilibrium between flowthrough water and top sediment (5 cm) were characterized as a quasi "V"-pattern, and the MPAS ranged from -0.04 to 0.46 mg cm(-2) during the steady-flow observation. The newly-trapped P was mainly found in Al-bound P and subsequently as Fe-bound P, which would be helpful for sediment P immobilization. Based on our findings, the sediment of the tested wetlands could retain external P from agricultural land by as much as 10-30 times the area of itself, which accounts for approximately 3.3-10% of the watershed area.
流域水质受到农业活动导致的养分富化的严重影响。了解水文对磷动态的影响，可以优化河岸湿地的生态功能，以减少非点源污染。选择下渚湖湿地进行野外磷调查，并进行了两个典型的水文批量研究，每个研究持续 35 天（模拟旱季的静态柱观测和模拟雨季的稳流水槽观测），以了解泥沙磷动态，并评估磷固定能力。在 31 个采样沉积物中，平均平衡磷浓度为 0.02mg/L，普遍低于上覆水中平均溶解反应性磷浓度，表明其具有作为磷汇的生态作用。在静态模拟观测中，在前 3d 内存在快速吸附过程，随后是较慢的吸附过程，单位沉积物表面吸附的磷量（MPAS）达到 0.16mg/cm2。在稳流观测过程中，穿透水和顶层沉积物（5cm）之间的磷平衡时间曲线呈现准“V”型，MPAS 范围为 0.04-0.46mg/cm2。新捕获的磷主要存在于 Al 结合磷中，随后是 Fe 结合磷，这有助于泥沙磷固定。根据我们的发现，受测试湿地的泥沙可以保留来自农业用地的外部磷，其保留量可达自身面积的 10-30 倍，约占流域面积的 3.3-10%。
