Sources and contamination assessment of heavy metals in the green land soils in Tongzhou District,Beijing
[Objective]The types of land use in Tongzhou District of Beijing have changed greatly.Heavy metals in the soil of green land were investigated,source analysis and risk assessment were carried out to understand whether the current use of green land meets the requirements of cleanliness and safety,and suggestions on risk prevention and control of heavy metals were given.[Method]The pH values and total amounts of heavy metals including Cd,Cr,Pb,Hg,As,Cu,and Zn in 60 surface soil samples from the study area were determined.Source apportionment was carried out using Principal Component Analysis and the Absolute Principal Component Scores-Multiple Linear Regression(APCS-MLR)receptor model.The assessment of heavy metal element pollution was conducted using the Geo-accumulation Index method and the Potential Ecological Risk Assessment method.[Result]The average contents of 7 heavy metals Cd,Cr,Pb,Hg,As,Cu and Zn in the soil were 0.53,47.87,11.95,0.25,6.71,4.64 and 51.21 mg·kg-1,while the average content of the remaining elements were below the background.All of the samples'heavy metal concentrations were less than the screening values for Soil Pollution Risk Control Standards for Agricultural Land(GB 15618-2018).Principal component analysis demonstrated that Cd,Pb,Hg and As were influenced by human sources,including coal combustion,traffic pollution,industrial and agricultural activities pollution;Zn originated from natural sources and was related to the soil parent material;Cu and Cr were mixed sources reaulted by soil parent materials and agricultural pollution.The contribution rates of sources calculated by APCS-MLR were as follows,a certain amount of Cd accumulated on the surface came mostly from human sources(92％);Hg was from source 3(29％),source 1(17％),source 4(13％),and there were also 35％unknown sources,which were suggested as mixed sources.Moreover,sources 1,3,and 4 were all anthropogenic sources,while source 2 was a natural source.Environmental quality evaluation of green soil was investigated through the ground accumulation index,which illustrated that Cd and Hg performed a higher ecological risk response.Most of the comprehensive potential risk values in the study area were slight and medium potential ecological risks,only few points were belonged to severe ecological risks.[Conclusion]The study shows that the overall risk level of green land soil in Tongzhou District is in the middle and low risk.The main elements causing the risk are Cd and Hg,which are the priority control elements of ecological risk,and can be controlled from the control of coal burning,traffic and industrial emissions.[Ch,5 fig.4 tab.32 ref.]
green land soilheavy metalcontamination assessmentsource apportionment
万方数据
维普
