[Ecological risk assessment of contaminated soil using improved "Weight of Evidence"approach:A case study of electroplating site in Jingjiang, Jiangsu, China].

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.