| Facing limited remediation resources of Chinese contaminated sites,how to effectively manage the contaminated sites and mitigate potential harms to human beings and ecosystems becomes hot topic.In China,the studies on categorized management of contaminated sites are still in the initial stage.This paper discusses the ranking system for the management of contaminated sites by establishing a comprehensive assessment model combining risk grading and risk importance grading.The review of the regulations and assessment methods for contaminated sites in different countries reveals that the common core concept of the ranking system for contaminated sites is to identify the sites with higher environmental and health risks for implementing remediation actions.However,different countries have different assessment frameworks,indicators and methods.Comparative analysis of the hazard ranking system of the United States and the national classification system of Canada gives insights to build up innovative indicator systems and assessment methods.This paper takes a similar framework as the Canadian national classification system and constructs the classification components for contaminated sites including three dimensions: contaminant characteristics,transmission pathway and contaminant exposure recipients.Meanwhile,the screening of assessment indicators not only consults the related studies of soil and groundwater risk assessment,but also takes the features of contaminated site investigation in China into consideration.The study proposes the risk expression coupling risk grading and risk importance grading,and after non-dimensionalization,the risk category of the contaminated sites can be qualified.An expert survey is conducted among experienced leading experts to determine the weights of different categories of indicators by the analytic hierarchy process.A fuzzy comprehensive evaluation model is constructed as an innovative classification system for contaminated sites based on the hierarchical structures.The subordinative degree of evaluation factor is described by triangular fuzzy numbers.A trial run of this model is implemented for a site of an original pesticide plant and the result classifies the site as high risk category,which shows that the model is generally practical and can be used as a decision making tool to determine the risk category of contaminated sites. |
