Study On Pollution Characteristics Of Industrial Sites In Chongqing And Sustainable Remediation Mode Of Contaminated Sites

During remediation of industrial contaminated in Chongqing,there are problems such as lack investigation,low resource utilization efficiency,and serious secondary pollution.The pattern of remediation have to be imroved.Domestic and foreign research shows that the sustainable remediation model puts forward new requirements for the management and restoration of industrial contaminated sites from the aspects of site investigation,restoration target,technology,decision-making,and whole process control of remediation,which points out the future direction of the remediation of industrial pollution sites.However,the sustainable remediation pattern of contaminated sites needs to be judged by sustainability evaluation.Different conclusions may be obtained under different site conditions,policy backgrounds and economic development levels.The evaluation and identification of sustainable restoration models are the key issues to be solved.There are three core problems to be solved in the evaluation and identification of the sustainable remediation model of contaminated sites in Chongqing:First is exploring the soil characteristics and pollution characteristics of industrial polluted sites in Chongqing,and the second is exploring the meaning of the sustainable remediation under the theory of ecological civilization construction in China,the third is to build a set of sustainable repair model evaluation system that is consistent with the domestic policy and is compatible with the current economic situation and repair technology level of Chongqing.Through the sustainability evaluation of typical cases in Chongqing,the sustainable restoration mode of contaminated sites in Chongqing was identified,and suggestions for improvement of contaminated sites in Chongqing were provided.The main conclusions of this study are as follows:(1)Heavy metals such as lead,copper,chromium and zinc and petroleum hydrocarbons are the main pollution factors in the soil of polluted sites in Chongqing.Heavy metal-petroleum hydrocarbon composite pollution is the main composite pollution type;Typical pollutants such as lead,copper,chromium,zinc,nickel,benzene,benzo(a)pyrene and petroleum hydrocarbons are mainly from typical industrials in Chongqing,Which included chemical,steel,electroplating,smelting,automobile manufacturing and railway,shipbuilding,aerospace and other transportation equipment manufacturing.there are some correlations in industrial sources between copper,chromium,zinc and nickel,benzene and benzo(a)pyrene,chromium and TPHs.(2)The pH range of soil samples in contaminated sites in Chongqing is between4.9 and 10.0,which is mainly alkaline;the bulk density ranges from 1.63 to 1.85 g/cm~3,with an average of 1.75 g/cm~3.The soil-rock ratio of contaminated sites in Chongqing is between 10%to 25%;the water content ranges from 15%to 30%;the soil properties are mainly loam and sandy loam,and the organic matter content is between 68 and 137g/kg.(3)The theoretical study of green sustainable remediation of contaminated sites shows that the interrelationship between the three major systems of environment,society and economy constitutes the basic connotation of sustainable concepts.The theory of ecological civilization construction further refines the considerations of“sustainability”:including promoting scientific and technological innovation,developing green industries,promoting energy conservation and emission reduction,developing circular economy,strengthening resource conservation,protecting and repairing natural ecosystems,and comprehensively promoting pollution prevention and control.Actively respond to climate change,strictly abide by the resource and environment ecological red line,raise the awareness of the ecological civilization of the whole people,and encourage the public to participate actively.The contaminated site restoration theory proposes a common pollution site restoration model.Some general conclusions about sustainable restoration models include that sustainable restoration of contaminated sites tends to be treated in situ rather than ectopic,preferring to use joint repair techniques rather than single repair techniques.(4)This study has developed a set of seven first-level indicators including human health,environmental quality,energy and resource conservation,economic input,economic benefits,social satisfaction,and comfort.Continue to repair the evaluation index system.The two sets of evaluation methods are used to form the weights of the six sets of indicators based on the opinions of the stakeholders.The index system and the index weights together constitute the evaluation system for the sustainable restoration mode of the contaminated sites in Chongqing.(5)The site ectopic repair mode is more sustainable than the in-situ repair mode and the off-site repair mode.It can further improve Chongqing by reducing transportation distance,improving soil recovery and utilization after repair,and increasing water recovery and utilization.The sustainability of the city's contaminated site restoration process.