河口水生态风险响应机制研究

As a sensitive important symbol of the ecological health of the basin end, estuary is the last barrier of whole watershed. The estuarine ecosystem is a complex giant system, a large number of substances, energy and information exchange are accompanied by each of its dynamic changes. However, the estuary of Haihe River Basin is facing the water pollution, habitat degradation, coastal erosion, estuarine siltation, and other environmental problems under the strong human activities, which resulting in increasing of water environment risk. Thus estuary risk had become the focus and hot topic of the science and water managers in relevant fields. On the basis of the researches at home and abroad, this project aim at the international frontier and hot issues and develop the model through improving and optimizing the parameter for the water ecological risk assessment. On the one hand, to determine the main source and stressors in the estuary area and to clear the response relationship between sources, stressors, habitats, and the endpoint through the analysis of human disturbance, pollution, river diversions, invasive species, global climate change and other key drivers. And then to optimize the relative risk model through considering the probability that source release stressors and expanding the exposure response coefficients, to build a risk assessment model that reflect the relationship of source, stressors, habitat and endpoint. On the other hand, water quality, water quantity and water ecosystem will be selected as the endpoints based on the environment characteristics in the estuary. Ecological risk value of the Haihe River estuary will be calculated based on the optimized model and risk maps will be drew. According to the results of risk, the dominant risk factors and stressors of estuary ecosystem will be analyzed, as well as risk response mechanism and the regional spatial variation would be revealed. At last, the uncertainty of assessment results and model parameters will be analyzed by using Monte Carlo simulation method. The research results provide a scientific basis and technical support for the risk management departments and policy makers of estuary or watershed.

河口作为流域最后的生态安全屏障，生态环境敏感脆弱，对于流域健康和水环境安全具有重要的地位和指示作用，已成为流域水生态恢复的瓶颈和焦点。本项目以生态毒理学为基础，应用风险等级图和暴露-响应等宏观与微观相结合的方法，通过辨析河口水生态风险源和胁迫因子、GIS生境分析、筛选响应指标构建响应路径，分析各路径间暴露-响应关系，构建风险响应网络关系，揭示风险响应机制和区域风险空间分异规律。以具有强人为干扰和复合环境污染为主要特征的海河流域河口为研究案例，以实验室和野外原位生态监测和模拟数据为基础，确定响应路径等级系数，对海河流域河口水生态风险进行诊断、评价和不确定性分析，揭示流域水生态风险响应机制，为河口生境恢复及流域风险管理部门和决策者提供科学依据和技术支持。

基于河口入海水量减少、水质恶化和生态系统退化交互影响的复杂性，建立适用于流域、子流域和河口等不同尺度下水生态风险评价模型与方法。基于现有水资源分区和流域生态水文分区方式，通过辨识风险源、胁迫因子以及生境和终点间的关系，构建了河口风险响应网络模型（RNM），增加了“风险源暴露”系数和“终点-生境”响应系数以减少不确定性。构建并应用水质-水量-水生态综合模型（APRFW模型），以水生态系统功能为表征，为流域内河口与其他生态单元进行生态系统健康比较研究提供科学方法。. 本项目对海河流域滦河口、海河口和漳卫新河口等进行研究，以生态毒理学为基础，采集并分析各河口水样、沉积物样品、浮游生物、底栖生物和天然生物膜等样品，辨析各河口生态系统中营养物质、重金属、多环芳烃等污染物的时空分布特征，揭示河口水生态风险响应机制。筛选河口水生态风险源、胁迫因子与响应指标1），确定海河河口7类主要风险源包括旱涝、海水入侵、污染型工业、水产养殖、船舶运输、水利工程和城镇化。2）确定三类13种胁迫因子包括物理因子（悬浮物、过度用水、水土流失、径流改变、入海水量减少、海岸侵蚀）、化学因子（需氧有机物、无机/有机毒物、内分泌干扰物、营养物）和生物因子（病原体和生境破坏）。3）分析三个尺度生态风险响应指标，包括微生物种群、生物膜群落和食物网系统。表层沉积物细菌的多样性指数沿上游至入海方向呈下降趋势。生物膜生物量和各种胞外酶活性比较结果表明：海河河口>滦河河口>漳卫新河河口，基质粒径是对生物膜群落影响较大的环境因子。光强、营养盐、淡水入流水量和溶解氧是影响海河河口GPP、R24和Pn最主要的环境因子。以上三尺度分别从分解者、群落和食物网角度反映河口物理、化学和生物因子的潜在生态风险。. 研究成果主要以论文和会议报告形式发表。项目资助发表论文12篇，其中SCI论文9篇。培养1名博士后、3名博士生及4名硕士生。