Tiered ecological risk assessment combined with ecological scenarios for soil in abandoned industrial contaminated sites

Redeveloping abandoned contaminated industrial sites can effectively relieve urban land shortages. An economical and accurate ecological risk assessment (ERA) approach that guides remediation measures for enormous sites is therefore needed. A tiered ERA approach that combined with ecological scenarios is proposed in this study. At first step, prospective land use of site and the bioavailability of contaminants were integrated to create six ecological scenarios and different protection goals assigned to each ecological scenario. Industrial information and soil parameters of specific sites were then obtained to identify major contaminants and matching scenario. With collected toxicity data, tiered ERA combining a hazard quotient (HQ) and joint probability curve (JPC) was used to assess the ecological risk, under corresponding scenario. Recommendations for regulatory management were given based on the ERA and the tolerance of decision makers to ecological risks. This approach was validated using case studies at four abandoned industrial contaminated sites. The results indicated that the ecological scenarios defined as II and V matched with each site, respectively, and that Cd, Cu, Ni, and Pb were the major contaminants and had different ecological risk values under different ecological scenarios. Different remediation measures should be adopted to address different levels of ecological risk. The results demonstrated that the combination of a tiered ERA with matching ecological scenarios effectively reduced workloads and improved ERA accuracies for abandoned industrial contaminated sites with redevelopment potential.