Research On Evaluation Of Core Removal Rate And Health Risk Assessment Of Direct-push Drilling Rigs In Typical Sites

In recent years,with the acceleration of urbanization,a large number of contaminated sites left after the relocation of heavy polluting industrial enterprises need to be investigated and repaired for re-planning and utilization.At present,in the process of site survey and sampling in my country,soil samples collected by drilling equipment are often severely compressed,which makes it impossible to accurately grasp the actual pollution status of the site.In response to this practical problem,the research selected a direct push drill rig commonly used in site sampling surveys in China and abroad as the research object to explore the influence of soil properties on its sampling effect,and on this basis,select a typical contaminated site for pollution identification and health risk assessment are expected to provide reference for the investigation of contaminated sites in China.The main contents and conclusions are as follows:(1)Taking the four basic properties of moisture content,bulk density,porosity,and particle size distribution as the influencing factors.The direct push drill rig was used to collect soil from different types of sites,and then analyze the correlation between these four properties and the core rate of the sample in both the horizontal and vertical directions.It was found that the coring rate was significantly positively correlated with the bulk density at different depths at each point,and was also significantly positively correlated with the content of silt sand at different points at the same depth.However,combining the two directions,there is no obvious correlation between the compression of the soil and these parameters.Therefore,the direct push drill rig is suitable for most stratums and can meet the requirements of survey and sampling in most sites in China.(2)According to the survey and sampling analysis results of a typical waste electrical appliance dismantling site by a direct push drill,the concentration of pollutants in the dismantling area is generally higher than that in the non-dismantling area,and the pollutants are mainly concentrated in the soil surface miscellaneous fill.In the eighty-nine samples collected at seventeen points,the content of Cd is ND-15.3 mg·kg^-1,Hg is ND-3.1 mg·kg^-1,As is 2.2-38.1 mg·kg^-1,and Zn is 57-2470 mg·kg^-1.All samples did not exceed the standard.The content of Cu is 11-2870 mg·kg^-1and 1 sample exceeded the screening value by 0.44times;The content of Cr(?)is 13-426 mg·kg^-1,and 1 sample exceeded the screening value by 0.71 times.The content of Pb is 17-1350 mg·kg^-1,and 5 samples exceeded the screening value with the maximum exceeded the standard by 2.4 times;The content of Ni is 8-2240mg·kg^-1,and 8 samples exceeded the screening value with the maximum exceeding 13.9 times.The content of PAHs is 0.96-2023.17?g·kg^-1,and PBDEs is ND-4993.37?g·kg^-1,all samples did not exceed the standard.The content of total PCBs is ND-397.56?g·kg^-1,and one sample exceeded the screening value by 1.84 times.In this typical site,there are 5 pollutants that exceed the screening value of the first type of land used in the"Technical Guidelines for Risk Assessment of Contaminated Land in Zhejiang Province",which are Ni,Pb,Cr(III),Cu and PCBs.(3)Through the human health risk assessment of pollutants that exceed the screening value,Ni have two points respectively,which have carcinogenic risks,and Ni and Cu have three and one points respectively,which are unacceptable.Non-carcinogenic risk.Inhalation of particulate matter is the only way for Ni to have a carcinogenic risk.Oral intake is the main way for Cu to have a non-carcinogenic risk.Oral intake and skin contact are total PCBs that have a carcinogenic risk,and Ni has a non-carcinogenic risk.The total carcinogenic and non-carcinogenic risk assessment results showed that all points with unacceptable risks are basically concentrated in the dismantling area.In order to protect human health,the risk control value of this typical site pollutant should be based on the smaller value of the control value under the two effects of carcinogenic and non-carcinogenic,respectively Ni-475 mg·kg^-1 and Cu-1950mg·kg^-1,indicating that the two pollutants of concern in the soil of the dismantling area need to be repaired before they can be developed and utilized.