Soil Heavy Metal Pollution Characteristics and Ecological Risk Assessment——A Case Study of a Typical Agricultural Land in Chizhou City
In order to investigate the soil heavy metal pollution and ecological risk of a certain agricultural land,surface soil samples of a typical agricultural land in Chizhou City were collected and analyzed for the content of 8 heavy metals,Cd,As,Ni,Hg,Pb,Cr,Cu and Zn.The ecological risk of heavy metal pollution was evaluated by single factor index method,Nemerow comprehensive pollution index method and potential ecological hazard index method.The results show that:The average contents of Cd,As,Ni,Hg,Pb,Cr,Cu and Zn were 0.71,25.80,33.31,0.23,33.17,46.59,37.15 and 130.28 mg·kg-1,respectively.The contents of Cd,As and Ni all exceeded the screening values stipulated by national standards to varying degrees.In addition,the average and median values of other heavy metals exceeded the background values except Cr.The average value of single factor evaluation pollution index of each heavy metal element is Cd>As>Cu>Hg>Ni>Zn>Cr>Pb,and the average value of single index of Cd is light pollution level,and other heavy metals are pollution-free level.In the surface soil samples,the proportion of priority protection and safe utilization were 15% (6/40)and 85% (34/40),respectively,and the pollution at each point was in the controllable range.The proportions of safety,warning line,light,moderate and severe pollution levels in Nemero's comprehensive pollution evaluation were 7.5%,15%,45%,30% and 2.5%,respectively.The average composite index was 1.77,exceeding the warning line level and belonging to the mild pollution level.Cd was the most important influencing element,which was consistent with the results of single factor evaluation.The single factor potential ecological risk(Ei)index of the eight heavy metals was Hg>Cd>As>Cu>Ni>Pb>Cr>Zn,and the average comprehensive potential ecological risk(RI)of heavy metals in soil was 194.73,indicating a moderate ecological risk level.Among them,Cd was the heavy metal element with the highest pollution risk in the study area.Hg is a heavy metal with high potential ecological risk,so it is necessary to strengthen the risk control of Cd and Hg.The acidification trend of farmland soil in this region is an important factor in the accumulation of heavy metals.Other human activities increase the risk of heavy metal accumulation,so it is necessary to strengthen the measures for the safe utilization of the soil effects.
agricultural landheavy metal pollutionpollution characteristicsevaluation of ecological risk
国家科技期刊平台
NSTL
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