Soil Pollution Investigation And Atrazine Distribution Characteristics And Risk Assessment In A Producing Pesticide Factory

With the advancement of industrialization in China,soil pollution is getting intense.To effectively reduce the mass incidents caused by soil pollution,China has issued a series of technical documents that strictly require soil pollution investigation and risk assessment on construction land.However,the related work is mainly focused on the abandoned and relocated enterprises,instead of the enterprises in production,let alone the research on the producing pesticide enterprises.More importantly,the few related research claimed that the pollution status of producing enterprises was universal and the risk was too high to ignore.Therefore,it is very necessary to make full pollution investigation and risk assessment of producing pesticide enterprises,so as to master its pollution status and risk situation.Herein,this work selected a producing pesticide factory in Shandong Province as the research object,and analyzed the distribution of pollution sources and main contaminants on the site based on the collected data.29 points were set for stratified sampling(the surface layer is 0.0～2.0 m,the middle layer is 2.0～4.0 m,and the deep layer is 4.0～6.0 m)to determine the concentration of heavy metals,VOCs,SVOCs and organic pesticide indicators.In addition,the main characteristic pollutant(atrazine)was sampled at a fixed point,and the content of atrazine in the soil at different periods(February 2019,May,October,and February 2020)was determined.Next,environmental quality assessment was carried out to clarify the pollution status of the site,and the distribution characteristics of atrazine pollution were analyzed.On this basis,the risk assessment of atrazine pollution was carried out,some relevant parameters of the second-type land use model in the national risk assessment guidelines were revised,and the difference of the risk assessment results before and after the parameter revision were analyzed.The main contents and conclusions are as follows:(1)Through the investigation of the pollution status of the site,it is determined that the key pollution areas are the production workshops,raw materials and finished products warehouses,hazardous waste warehouses,storage tank areas,and the representative pollutants are toluene,xylene and atrazine.Soil Environmental Quality of Construction Land Soil Pollution Risk Management and Control Standards(For Trial Implementation)(GB 36600-2018)was selected as the reference standard for the second type of soil screening value,and the single factor index method was employed to evaluate the soil environmental quality in this work.Results illustrated that the soil environment in the research area has been polluted by atrazine to a certain degree,along with some seriously polluted area.Additionally,there was no pollution of other elements.(2)Classical statistical methods and geostatistical methods were used to analyze the test data of atrazine in the sampled soil in February 2019,and it was found that the spatial distribution of atrazine in the pesticide production site had obvious regularity:In the horizontal direction,the soil pollution of each layer showed a trend of spreading around the original drug production workshop;in the vertical direction,the pollution degree of the surface soil and the middle soil in all areas of the site is similar,which is higher than that of the deep soil(not exceeding the standard).Due to the different nature of the soil layer and production mode,there exists a big difference in the vertical distribution of atrazine in the soil of the producing pesticide plant and the relocated one.(3)According to the sampling data of four periods,it was found that the spatial and temporal distribution of atrazine in producing pesticide site had obvious regularity:in the horizontal direction,distribution characteristics of atrazine in each soil layer in different periods are basically paralleled to that of February 2019.In the vertical direction,atrazine distribution was mainly affected by natural factors,and showed a trend of gradual migration from the surface layer to the middle layer,and the concentration of atrazine in the deep soil remains basically unchanged.After a year of investigation,it was found that the company’s production activities contributed to atrazine contamination in the soil in areas where pesticide preparations were produced and downwind areas.Therefore,pollution sources in pesticide production areas should be checked,and pollution prevention and control should be strengthened during the production of atrazine(4)Based on the collected data(the attendance of employees in producing pesticide enterprises,etc.),the parameters of adult height(Ha),adult body weight(BWa)and average time of carcinogenic effects(ATca),adult exposure frequency(EFa),adult daily soil intake(OSIRa)were revised,and the assessment results before and after the modification were obtained:Before parameters modification,the site restoration was strongly required with the total carcinogenic risk of unacceptable 2.74E-06.Satisfactory,after parameters modification,the total carcinogenic risk is acceptable 8.49E-07.In addition,through the sensitivity analysis of the modified parameters,it can be found that the sensitivity parameters(EFa,ATca,BWa,OSIRa)have a greater influence on the assessment results.Consequently,in the risk assessment of producing pesticide sites,the accuracy of the above sensitivity parameters should be ensured as far as possible.