Distribution,ecological risks,and sources of heavy metals in soil of typical agricultural areas in Liaocheng City
Typical agricultural areas in Liaocheng City were selected as the research object,84 shallow soil samples were collected and the content of 8 heavy metal elements was measured.The spatial distribution and potential ecological risks of heavy metals in soil were analyzed by using GIS and geostatistical methods,geoaccumulation index method,and potential ecological risk index method.The possible sources and contribution rates of heavy metals were identified through correlation analysis and Positive Matrix Factorization(PMF)model.The results indicate that:1)The average content of As,Cd,Cr,Cu,Hg,Ni,Pb,Zn in the study area is 1.05,1.16,1.28,1.06,1.08,1.05,1.07,and 1.11 times that of the background value of the soil environment in Liaocheng City.Except for the maximum value of Cd,which is slightly higher than the risk screening value standard for agricultural soil pollution in GB 15618-2018,all other elements are less than the risk screening value.2)The average geoaccumulation index of each heavy metal is Cr＞Cd＞Zn＞Pb＞Hg＞Cu＞As＞Ni in descending order.Among them,Hg and Cd have the greatest spatial variability and the highest degree of local accumulation,with 21.4％and 6.0％of the sampling sites being slightly to moderately polluted,respectively.3)The potential ecological risk assessment results indicate that Hg has a slight to strong ecological risk,while Cd has a slight to moderate ecological risk.The other elements are all of slight ecological risks,and the overall ecological risk is relatively low.4)The source analysis results of the PMF model indicate that there are four main sources of heavy metals in soil,namely natural sources caused by geological background,mixed sources of coal burning and transportation,industrial sources,and agricultural sources,with relative contribution rates of 25.33％,35.92％,22.40％,and 16.35％,respectively.As and Ni are mainly from natural sources,Cd,Zn,Pb,and Cu are mainly derived from coal-fired activities-transportation,Cr is mainly affected by the com-bined effects of geological background and atmospheric sedimentation from industrial sources,and Hg is mainly affected by agricultural activities such as fertilizer and pesticide application.
heavy metals in soilgeoaccumulation indexpotential ecological risk indexPMF modelsource parsing
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