Study On Soil Sampling Layout Method In Industrial Site Based On Conceptual Site Model

At present,soil pollution in China is becoming more serious increasingly.Mastering soil pollution status is an important basis for soil pollution prevention and supervision.Investigations of soil pollution are needed in industrial sites with intended use changes,aiming to identify soil pollution and provide a basis for further detailed investigations.Judgemental sampling method is a commonly useful sampling method.When using this method to collect soil samples,it is often difficult to accurately capture soil pollution points due to insufficient consideration of site characteristics,incomplete site information,and inconsistent estimation of various factors.Based on the low quantitative degree of the existing soil sampling professional judgment point layout method,it is of great significance to construct a quantitative evaluation of soil sampling method and apply it to identify soil pollution in industrial sites.Based on the conceptual site model(CSM),this paper constructs the evaluation index system of soil sampling points based on the characteristics of industrial site pollution sources and the process of pollutant migration and transformation,and determines the index weight.The evaluation value of soil sampling points was determined by weighted summation of indexes layer by layer,the evaluation grade of soil points was divided and the soil sampling points were determined.A soil sampling method is formed,which includes the evaluation index system,evaluation method,evaluation grade of soil sampling points and determination of soil sampling points.Finally,a typical industrial site in Chongqing was selected for case analysis.The constructed method was applied to determine soil sampling points,and the effectiveness of the layout method was verified by sampling and testing results.The main conclusions of this research are as follows:(1)Based on the analysis of the components of CSM and the content of each element,it is clear that the human health risks of the soil on the site mainly originate from the release process of pollutants and the process of migration and transformation in the environmental medium.The characteristics of the site pollution source and the influencing factors of the migration and transformation process of pollutants in the environmental medium are explored.There are 8 second-level indicators including pollutant type,pollutant emission form,pollutant discharge amount,distance from the pollution source,surface hardening of the structure and seepage prevention measures,soil,groundwater and meteorology,and 20 third-level indicators screened for By issuing questionnaires and collecting opinions,two evaluation methods are used to obtain the weight of each indicator.An evaluation index system for soil sampling points including2 first-level indicators such as pollution source and pollutant migration and transformation,8 second-level indicators such as pollutant type and 20 third-level indicators,and the weight of each index has been constructed.(2)The soil sampling points evaluation indicators are divided into site basic indicators and site indicators.The basic indicators of the site include all three-level indicators in the second-level indicators of pollutant type,pollutant discharge form,pollutant discharge amount,meteorology,soil,and groundwater.Point indicators include all three levels of indicators in the distance from the pollution source,the surface hardening of the structure and the anti-seepage measures.The value of the indicator may change with the change of the point position.The evaluation value of soil sampling sites is obtained by summing the comprehensive scores of site basic indicators and site indicators,which are divided into three levels of "high,medium,and low" using the equal spacing method.Collecting samples of soil samples at points with an evaluation grade of medium and above,which forms a systematic soil sampling method.(3)2 typical industrial sites in Chongqing including a pesticide and chemicals manufacture site and an electroplating manufacture site were selected for case analysis.The constructed soil sampling method was used to evaluate the soil points in the site and screen the soil points,and then soil samples was collected and tested.The results showed that the percentages of chloroform,hexavalent chromium,nickel,and 1,2-dichloroethane in the middle-grade soil points where sampling was performed were100%,75%,50%,and 40% respectively.All soil samples with a medium evaluation level have identified soil pollution to varying degrees;soil samples with a low evaluation level don’t ha pollutants detected in all soil samples.The test results are basically consistent with the predicted results of the soil sampling method,which indicates that the soil sampling method constructed in this study can be better applied to the identification of soil pollution in industrial sites.