侵蚀作用下水库消落带磷素的迁移转化机制

The water level fluctuating zone of reservoir environment is significant affected by both surrounding water and terrestrial ecosystems. The topography and landscape feature varies under erosion conditions. The highly complex variation of the environmental conditions have greatly affected the transport and transformation processes of phosphorus. Transport and transformation of phosphorus in the water level fluctuating zone of reservoir has aroused great concern in recent years. Related studies commonly focused on the influence of physical and chemical properties of water and sediment interface on phosphorus transport and transformation, and the soure-pool function of the water level fluctuating zones. Few studies have focused on its environmental behavior under erosion conditions, caused by the cyclical changes of water levels fluctuation and runoff erosion. In this study, the water level fluctuating zones of the Danjiangkou Reservoir is selected as the study site with an opportunity of the first water diversion of "The South-to-North Water Transfer Project (Middle Route)" in 2014. Based on the development of modern measurement methods and related modelling studies, the erosion and processes will be traced by real time monitoring. In this study, the topography and landscape feature changes caused under erosion conditions, and the relationship between particle concentration and transport and transformation characteristic of phosphorus will be described; the phosphorus enrichment and release under the anti-natural flood blight conditions will be assessed. The specific objectives of this study are to: reveal the characteristic and transport mechanisms of exogenous runoff from different land use/landscape feature regions; reveal the influence of the topography and landscape feature variation on phosphorus transportation and retention; quantitatively reveal the phosphorus transport and transformation mechanisms under erosion conditions. This study might provide theoretical and practical basises for the effective ecological restoration and conservation on water level fluctuating zones of reservoirs.

由于水域及周边陆域生态系统的共同影响，水库消落带发生着严重的侵蚀现象，造成了消落带坡面形貌及景观特征的变迁，影响了磷素的迁移转化规律。目前，消落带磷素行为的相关研究主要集中在水-沉积物界面理化性质的影响及源汇转换上，缺乏针对侵蚀冲刷与淤积过程的磷素迁移转化机制研究。本项目拟选取南水北调中线工程水源地--丹江口水库的消落带为研究对象，分析反季节水位波动、外源径流冲刷共同作用下消落带形貌及景观变化规律，以颗粒浓度变化为轴线，探讨不同陆域景观背景的影响、磷素迁移过程对消落带坡面形貌及景观变化的响应、反季节水位波动下消落带磷素的行为趋势，研究固体浓度效应的微观机理及颗粒浓度变化与磷素的迁移转化特征的关系。阐明侵蚀作用下消落带磷素迁移转化机制，为水库消落带生态修复与管理奠定理论基础。

由于水域及周边陆域生态系统的共同影响，水库消落带发生着严重的侵蚀现象，造成了消落带坡面形貌及景观特征的变迁，影响了磷素的迁移转化规律。本项目选取南水北调中线工程水源地——丹江口水库的消落带为研究对象，开展了相关文献计量分析、原位样品分析、消落带侵蚀观测、模拟降雨冲刷试验、野外水位波动模拟实验、吸附解吸试验、交叉型吸附等温式构建、颗粒物微观信息表征、磷素地表迁移行为定量化表达模型构建等研究，分析了固体浓度效应的微观机理及颗粒浓度变化与磷素的迁移转化特征的关系，研究了反季节水位波动、径流冲刷共同作用下消落带磷素迁移转化规律。主要研究结果如下：（1）利用XRF、BET、SEM、FTIR等微观表征方法和Intra-particle diffusion、交叉型吸附等温式等模型，获取了消落带沉积物理化性质及颗粒物组成特征，明确了消落带颗粒物对磷素的吸附解吸特征及微观机制；（2）揭示了颗粒物粒径及浓度变化、pH、反季节水位波动等因素对消落带磷素迁移转化的影响；（3）证明了磷素-消落带颗粒物体系中存在固体浓度效应，并基于“第三相理论”解释了固体浓度效应影响；（4）将磷素迁移行为的主控因子及不同地貌和景观特征等影响因素参数化，开发了定量刻画磷素迁移过程的分布式模型，并在多个流域应用。本研究成果为消落带生态修复与流域管理提供了科学依据，为水库磷污染综合防控的整体工程布局和单点工程设计提供了技术支持。