复杂污染场地的风险管理挑战及应对

复杂污染场地中土壤和地下水介质的非均质性、污染物形态归趋变化的复杂性是导致复杂污染场地调查、风险评估与修复过程存在较大不确定性的主要原因.基于侵入式采样和实验室样品分析等高成本调查技术无法理想反映复杂场地的真实污染分布，简单的定值风险评估结果则具有较大的不确定性，线性化场地管理技术体系不能适应复杂污染场地风险管理面临的不确定性挑战.结合国内外实践经验，本文提出"二精一优"的场地风险管理技术方法体系，即:①基于"有效数据理论"的定量测试与半定量实时监测技术相结合的精准调查技术；②基于污染物形态归趋规律，综合采用基于生物有效性、多证据和概率分析等多种手段的精细化风险评估技术；③动态调整优化的非线性场地风险管理技术框架. 

Challenges and Response to Risk Management of Complex Contaminated Sites

In recent years, with the acceleration of urbanization and the adjustment of industrial structure of China, contaminated sites in urban areas are sustainably cleaned and redeveloped. However, due to the heterogeneity of soil and groundwater pollution, the management of contaminated sites faces many uncertainties although China has issued a series of environmental laws, regulations and technical standards. This paper reviewed the major challenges of the regulatory approaches in risk management, especially in complex contaminated sites, and drew the following conclusions: (1) The heterogeneity of the soil matrix and geologic conditions in soil organic maters, soil particular sizes, permeability and hydraulic conductivity and complexity of fate and transport of contaminants are the major uncertainty issues facing the current regulatory site investigation and risk assessment. (2) Current site investigation approach based on intrusive sampling and sample analyzing in laboratories can not provide the reliable visualization of site contamination, and the fixed-value risk assessment approach may not properly deal with the uncertainty of the complexity of the sites. This paper further introduced high resolution site characterization and adaptive management methods: (1) to improve the quality of the site investigation based on 'effective data' concept by combining the 'precise' data generated by analytical method and the 'screening data' generated by screening tools; (2) to apply a tiered risk assessment framework by incorporating bioaccessibility/bioavailability and multi-line of evidence and probabilistic risk assessment approach for coping with the uncertainty; and (3) to adopt adaptive site management framework for dynamically optimizing remediation process.