重工业源引起的流域水环境风险累积特征与传导趋势研究

Currently, basin has been become one of the region that facing largest ecological pressure and environment risk. As the association of water ecological risk in the internal of basin, it has important practical significance to explore the risk associated mechanism and spatial conduction characteristics for protection of watershed environmental health and maintenance of the ecological safety. With the rapid industrialization process, aquatic environmental risks in basin had been strengthened severely especially in the heavy industrial area, and risk assessment results had become one of the manager's bases for decision making. The traditional methods for water environmental risk assessment is mostly based on the status analysis of a single pollutant or ecological event, and the complex risk conduction path and difficult quantitative become the major bottleneck which are restricting risk prediction research. Taizihe River Basin, a typical heavy industry area basin in northeast China, will be selected as the study case and heavy industrial sources will be selected as the risk source. Based on environment risk assessment theory, this project will seek the risk cumulative characteristics and conduction trends of industrial source in the heavy industrial area by using macro-microscopic combination method include GIS habitat analysis and exposure-response monitoring. The research contents includes: (1) build conceptual model through identifying industrial factors, associated elements and key node of water environment risk; (2) calculate cumulative risk value in node based on response model; (3) analyze release direction, path chain and coefficient of risk at each node based on the risk-based energy theory and river network distribution, and draw a spatial conduction trends diagram of water environmental risks for Taizihe River Basin. This project breaks the traditional concept, and the objective is to reveal the cumulative characteristics and spatial conduction trends of aquatic environment risk. Research results of this project will provide a support for theory and method of aquatic environment risk research for basin, and also provide a priority order for the management of the complex basin water environment, as well as against the outbreak of aquatic environment risk event.

快速的工业化进程导致重工业区流域水环境风险加剧，风险评价结果已成为管理者决策依据之一。传统的水环境风险评价多基于单一污染物或生态事件的风险现状分析，风险传导路径复杂且定量困难成为制约风险预测研究的主要瓶颈。本项目打破以往单纯的现状评价理念，以东北典型重工业区流域-太子河流域为研究对象，针对重工业风险源，应用GIS空间分析和暴露-响应监测等宏观与微观相结合的手段，一方面通过选取关键节点并计算其所在区域的水环境风险，揭示风险累积特征；一方面通过构建风险传导路径链，探讨风险传导趋势。具体内容包括：辨析风险源、因子、终点、节点等关联路径链，构建概念模型，并计算风险累积值；基于风险能量理论，结合流域河网分布确定风险释放方向、传导路径链及系数，绘制风险空间分异与趋势图。项目旨在揭示流域水环境风险累积特征与转移趋势，为风险评价与预测研究提供理论和方法支持，同时为现阶段复杂的流域水环境管理提供科学依据。

本研究以重工业区域太子河流域为研究区，筛选了风险源、压力因子、生境和响应终点，构建了水环境风险响应概念模型；提出了流域水环境传导路径等概念，测试了节点主要水质指标，计算了风险等级系数及综合风险指数，揭示了风险传导趋势；评价了Zn、Cu、Pb、Cd、Cr、和As的水体健康风险和沉积物生态风险，揭示了太子河流域重金属风险时空分布特征。研究表明，风险源主要包括采掘业、石油化工、冶金工业和装备制造业，生境为水域、耕地、林地、草地和城镇用地。研究区包括轻微风险区1个（R4），低风险区1个（R6），中等风险区2个（R3和R5），高风险区1个（R7），极高风险区2个（R1和R2）。太子河上游为主要风险累积区，中、下游为主要的风险传导释放区，对风险贡献最大的是TN和NH3-N，氮元素的超标构成节点水质主要风险源。丰、枯水期风险最高值均出现在下游断面，其中唐马寨、小姐庙、三岔河和古城子均呈现较高综合风险值。太子河主要重金属污染物为Cd和As，所引起的人体健康危害的个人年均风险均高于国际辐射防护委员会（ICRP）推荐的最大可接受风险水平。非致癌有毒化学物质Zn、Pb和Cu所引起的人体健康危害的个人年均风险集中在10-8•a-1和10-9•a-1水平，未超过推荐标准。沉积物重金属在所有点位均有极高生态风险，枯水期的风险高于丰水期。R4虽然处于相对最低风险水平，但重金属评价结果显示仍具有较高风险，因此，太子河流域整体水环境风险水平较高。