Ecological risk assessment of soil in contaminated sites provides the scientific basis for accurately developing soil quality standards, confirming remediation targets, and making safe use of contaminated soil. It thus is a critical mean to protect soil health and safety. "Weight-of-Evidence" (WoE) has been widely used in ecological risk assessment due to its systematic, integrated and scientific properties. However, most current WoE approaches are poor in objectivity and comparability because they rely too much on expertise scoring in weighing and the difficulty to collect complete evidence bodies with quantitative and comprehensive information. Focusing on those issues above, we developed an improved framework of WoE approach for ecological risk assessment of contaminated site soil based on the "Four-Step" framework of EPA coupled with the concept of hierarchy. Assessment methods and procedures for each tier were unified. Weights were weighed quantitatively through multiple criteria decision analysis. The relative independence among bodies of evidence was assured by the pre-establishment of hierarchy. The "site specific" was stressed based on matrix trails and field investigation. Finally, a case study in an electroplating site in Jingjiang was conducted to verify the approach. Results of the case study suggested that the approach was practical and that the assessment results were objective, scientific, and accurate.
污染场地土壤生态风险评估能够为准确制定土壤环境质量标准、污染土壤修复目标、土壤修复后效果评估及安全利用提供科学依据,是保障土壤健康和安全的重要手段。“证据-权重法”由于具有系统性、整体性和科学性的特点在风险评估中应用广泛。然而,当前“证据-权重法”大多依赖专家打分法进行权重设置,并且在实际操作中难以获得定量化的、信息全面的完整证据链,风险评估结果缺乏客观性和可比性。针对以上问题,本研究耦合美国EPA的四步法与层级法构建了“证据-权重法”污染场地土壤生态风险评估框架,统一了每个层级的评估方法与程序。采用多标准决策分析对权重进行定量化,通过预先设置证据链之间的层级来保证其相对独立性,基于基质试验和野外调查保证场地的针对性。最后,以靖江某电镀场地为案例进行实证研究,结果表明: 所构建的方法具有较强的可操作性,评估结果具有较高的客观性、科学性和准确性。.
Keywords: bioaccumulation risk; chemistry risk; ecosystem risk; ecotoxicology risk; site specific.