Research On Ecological Risk Assessment And Optimal Control Models For Remediated Groundwater Ecosystems

In recent years,groundwater contamination caused by petroleum products leakage from underground storage tanks and pipelines has become a major environmental concern.Petroleum pollutants may pose significant threats to the groundwater and the regional ecological environment.Therefore,it is increasingly desired to focus on petroleum contaminant remediation and ecological risk assessment in groundwater system be conducted.A naphthalene-contaminated aquifer impacted by a power plant in Anhui Province in China is selected as a case study.Firstly,the concentration of naphthalene in groundwater was simulated in this study,which has been treated for four periods based on pump technology.Secondly,this study presented a network environmental analysis with consideration of ecological risk assessment(ERA)within a naphthalene-contaminated groundwater remediation site.Finally,a bi-level optimization model is developed for groundwater remediation management,which can reflects the dependency relationships among different decision makers.The bi-level optimal strategies in four different remediation periods are then discussed based on stochastic inputs.By incorporating both direct and indirect ecosystem interactions,the risk conditions of the whole ecosystem and its components were quantified and illustrated by the ERA.In the bi-level optimal groundwater remediation management model,environmental and health-risk concerns were considered in the upper level,while economic concerns were in the lower one.The economic concerns must follow environmental and health-risk ones,which in turn must satisfy the economic concerns in an incentive manner to achieve their targets.The results demonstrated obvious effects caused by the groundwater remediation.The ecological risk was the lowest in ten years of remediation.Once the groundwater was contaminated,the contaminant's impact on soil micro-organisms was more significant than vegetation.But naphthalene had the most significant risk-impact on the herbivores and carnivores.As a result,when assessing the multi-receptor risk systems,the transmission and accumulation effect in communities can not be ignored.The bi-level strategies can not only satisfy the low cost of repair for decision makers by consulting the ratios of expectations,but also be able to achieve a lower ecological risk to avoid the result of single objective programming model of extreme,and further,these strategies can satisfy the different goals established by different decision makers.In summary,the results provide a scientific decision basis for the and risk assessment for the ecological systems exposed in petroleum contaminations.