利用着生藻类稳定同位素识别河流上游农业面源污染源研究

As agriclutural non-point source pollution (NPS) has become a major cause of environmental degradation, identifying the pollution source is the foundation for the NPS control in watersheds. River upstream is the key area for water quality safety of the entire watershed. However, for the land use type, terrain and river wate volume, the upstream area is easily affected by NPS. In China, continuous and comprehensive monitoring data are lack in most of upstream area of rivers. Though mechanism models, including SWAT and AnnAGNPS, have been widely used for NPS load estimation, they are not suitable for many upstream areas of Chinese watershed. The complex data preparation, American data structure and research background were all the limiting factors for these models well applied in China. In this project, the periphyton would be used as an indicator to identify the NPS pollution source in the upstream area of the Hun River. The Hun River is the major river of the Dahuofang reservoir which is the major water source in Liaoning Province. Combined with field survey and laboratory simulation, the stable isotope analysis techniques would be used to study the 15N and 18O stable isotopic composition in the periphyton which would grow in simulated NPS river water. The reaction of 15N and 18O in periphyton affected by pollutants concentration, time variation and their interaction of different NPS sources would be further studied. Based on the data got from above studies, we try to construct a model which could describe the relation of the periphyton stable isotopes to different NPS sources. Together with the model and field survey data the main NPS nitrogen source in the upstream of the Hun River would be identified. This study would provide a new way of NPS sources identifying and a theoretical basis technical support for the NPS load reduction in the upstream area of China.

农业面源污染已成为水环境质量下降的重要原因，明确污染源是治理的关键。河流上游对流域水环境安全具有重要影响，也是易受农业面源污染影响的区域。针对我国河流上游区普遍缺乏全面的监测资料，相关机理模型数据准备繁杂、应用效果受影响的实际情况，利用着生藻类作为指示生物，借助稳定同位素分析技术，通过室内模拟结合野外调查的方法，研究着生藻类稳定同位素组成对不同面源污染源的响应。深入探讨污染物浓度、污染时间等交互作用下藻类的稳定同位素组成变化规律，力图构建典型着生藻类稳定同位素比例组成与污染源、污染物浓度及污染时间的耦合模型，结合实地调查识别主要污染源，形成技术流程。以此作为河流上游小流域农业面源污染源识别的新途径，识别主要氮污染源。研究结果将有助于以更加有效的方法确定小流域农业面源污染的主要来源，也为量化入河污染物提供技术手段，为小流域面源污染负荷削减、保障河流水质提供理论依据和技术支撑。