区域地下水环境风险评价技术方法

针对我国在地下水环境风险评价技术方法储备不足的问题,提出区域地下水环境风险评价技术方法应遵循逐级筛选、分类分级评价的思路,突出对不同尺度的控制,将区域地下水尺度划分为区域(流域、平原)、局部地区(城市、单元)和场地(水源地、污染场地)3个层次. 通过分析区域地下水环境中风险源—受体—危害分析—生态终点的暴露响应途径,提出适宜大尺度区域地下水环境风险的评价方法；选用区域土地利用类型表征区域污染源,以地下水水质以及供水量变化为生态终点,采用相对风险模型分析大尺度区域环境风险. 针对大尺度区域内高环境风险区,采用源—路径—受体控制模型建立城市区域尺度地下水污染风险评价理论模型,并结合当地污染源特征、水文地质条件及水质现状进行局部地区地下水污染风险评价. 针对局部地区的高污染风险区,基于健康风险评价理论,突出水质安全保障,确定小尺度场地地下水健康风险的内涵与评价方法,提出场地地下水健康风险评价流程采用过程模拟方法确定污染物在包气带—地下水中的迁移转化,定量分析其对人体健康的影响. 下辽河平原区域地下水环境风险评价结果显示,高环境风险区位于沈阳浑河冲洪积扇区域,而细河是区域内地下水高健康风险区,应有针对性地采取保护措施. 

Technique for Assessing Environmental Risk of Regional Groundwater

Methods for assessing groundwater environmental risks are urgently needed to prevent pollution and facilitate development of scientific and rational groundwater protection measures. Methods for assessing regional groundwater environmental risk were developed, and a classification and grading evaluation process was conducted following step-by-step regional risk screening plan. During the process, different regional scales were high lighted and divided into three main levels:large-scale (basins, plains), middle-scale (city, unit) and small-scale (water sources, pollution site). For the large-scale areas, based on the way of “risk source-receptor-endanger-ecological endpoint,” the analysis of regional groundwater environment at a large scale was established. Land use types were employed to indicate the regional pollution sources, quantity and quality of groundwater were the ecological endpoints, and the relative risk model (RRM) analysis was applied for evaluation of regional environmental risks. For the high risk regions in the large scaled areas, the “source-path-receptor” model was applied for groundwater pollution risk assessment for the urban scale, combining with the characteristics of local pollution source, hydrogeological condition and regional groundwater quality, to describe the risk of contamination area. The process simulation method, a small-scale groundwater environmental health risk assessment based on the theory of health risk assessment, with the purpose of security water supply, was taken for the detailed risk area, to determine the migration of contaminants in the unsaturated zone-groundwater and the effects of quantitative analysis on human health. The developed methods were subsequently applied to identify the key risk areas in the Lower Liaohe River Plain. The results showed that the Hun River Alluvial and Flood Fan is at higher environmental risk of contamination, while the Xi River has a higher groundwater health risk; accordingly, appropriate protective measures should be taken for regional groundwater prevention.