The Investigation And Evaluation Of Chromium Slag Pollution Site Of Yongqing Chemical Plant In Gansu Province

With China's industrial modernization process and industrial restructuring,due to the imperfect legal system,there leaves a large number of chromium slag contaminated sites.The traditional contaminated site investigation method using sampling and analysis has the shortcoming of high cost,long cycle and other deficiencies.Therefore,it is necessary to explore an efficient and economical method of investigation.In recent years,high-density resistivity method has been widely used in contaminated site investigation,and achieved good results.In this thesis,high-density resistivity method and Luoyang shovel were used to detect and verify the semi-arid and homogeneous loess chromium slag contaminated sites in Yongqing Chemical Plant.The results find that high-density resistivity method can quickly and accurately detect the pollution range and pollution degree of contaminated sites.Three different configuration of electrodes,including Wenner device,the dipole device and the differential device,were employed during the field investigation.The detection effect of Wenner device and the differential device are much better than the dipole device.The inversion method and T ratio method are used for the data analysis.The inversion method is more effective.The contents of 12 kinds of elements such as Cr,As,Ni and Pb were measured.The results showed that the water content of the collected soil samples was uniform and the average water content was 20.13%.The loess site were polluted by Cr and were partially polluted by As.Based on the results of field investigation and laboratory analysis,the ecological risk assessment and health risk assessment of the chromium slag contaminated site in Yongqing Chemical Plant were carried out.The results show that the original chrome slag piling site has a strong potential ecological risk,high risk of carcinogenicity and non-carcinogenic;also there is a slight ecological risk,moderate carcinogenic risk and non-carcinogenic risk around the original chrome slag piling site and the original production plant.The Hydrus-1D software was used to simulate and predict the migration of chromium in the vertical direction of unsaturated homogeneous loess under irrigation and rainfall conditions.It showed that trace amount of chromium had penetrated into the cobble layer,and the invasion rate was gradually increased.Finally,according to the pollution situation,geological conditions and economic value of Yongqing chemical plant contaminated site,combined with the characteristics of remediation methods of various contaminated sites,it is suggested to use engineering measures and phytoremediation methods to repair the contaminated sites.