典型工业园区周边农田土壤重金属污染及生态危害评价

Assessment for heavy metal pollution and potential ecological hazard of farmland soil around typical industrial parks

为评价四川某工业园区周边农田土壤重金属污染程度及其潜在生态危害。采用石墨炉原子吸收分光光度法、冷原子吸收分光光度法和X射线荧光光谱法,分别对研究区域农田土壤中的Cd、Hg、As、Pb、Cr、Cu、Zn、Ni的含量进行测定,采用单项污染指数法、内梅罗综合污染指数法、污染负荷指数和潜在生态危害指数法对研究区域农田土壤重金属污染及潜在生态危害进行评价。结果表明,23个采样点中8种重金属含量存在一定差异,Cd和Zn的平均含量超过风险筛选值,其余重金属平均值均未超过风险筛选值。Pearson相关性分析表明Pb与Cd、As、Pb、Zn相互之间有极显著相关性。8种重金属均呈正态(或近似正态)或对数正态(或近似对数正态)的分布。8种重金属的单项污染指数顺序为Cd>Zn>Pb>Cu>Cr>As>Ni>Hg,其中Cd呈重度污染,Zn处于轻度污染,其余6种重金属相对处于清洁状态;综合污染指数顺序为Cd>Pb>Zn>Cu>As>Cr>Ni>Hg,重金属Cd、Pb、Zn为重度污染,As和Cu为中度污染,Cr为轻度污染状态,Ni处于警戒状态,Hg处于相对清洁状态。污染负荷指数评价表明,除18^(#)和13^(#)点处于无污染状态,其余点位均处于中等污染状态或强污染状态。区域污染负荷指数PLI_(zone)为2.36,为强污染状态。8种重金属的潜在生态风险指数顺序为Cd>Hg>As>Pb>Cu>Ni>Zn>Cr,潜在生态危害综合指数RI平均值为237.74。因此,Cd和Zn为研究区域农田土壤重金属污染的主要元素,不同采样点的不同重金属含量存在一定差异。研究区域农田土壤重金属污染处于很强状态,具有中等生态危害风险,Cd污染的潜在生态危害相对较大,值得高度关注。

To evaluate the heavy metal pollution and potential ecological harm of farmland soil around an industrial park in Sichuan Province,the contents of Cd,Hg,As,Pb,Cr,Cu,Zn and Ni in the farmland soil of the study area were determined by graphite furnace atomic absorption spectrometry,cold atomic absorption spectrometry and X-ray fluorescence spectrometry,respectively.The heavy metal pollution and potential ecological hazards of farmland soil in the study area were evaluated by single pollution index method,Nemerow comprehensive pollution index method,pollution load index and potential ecological hazard index method.The results showed that there were some differences in the contents of eight heavy metals in 23 sampling points.Except for the Cd and Zn,the average contents of the rest heavy metals did not exceed the risk screening value.Pearson correlation analysis showed that Pb was highly significantly correlated with Cd,As,Pb and Zn.8 kinds of heavy metals were in normal(or approximate normal)or logarithmic normal(or approximate logarithmic normal)distribution.The order of single pollution index of eight heavy metals was Cd>Zn>Pb>Cu>Cr>As>Ni>Hg,in which Cd was of heavily polluted and Zn was of slightly polluted,the rest 6 kinds of heavy metals are relatively in clean level;the comprehensive pollution index was in the order of Cd>Pb>Zn>Cu>As>Cr>Ni>Hg,heavy metals Cd,Pb and Zn were in severely polluted,As and Cu were in moderately polluted,Cr was in slightly polluted,Ni was in alert,and Hg was in relatively clean level.The pollution load index evaluation shows that,except for 18^(#)and 13^(#) points in pollution-free state,the rest points are in medium or heavy pollution state.The regional pollution load index PLI_(zone) is 2.36,indicating a heavy pollution state.The order of the potential ecological risk indexes of the eight heavy metals was Cd>Hg>As>Pb>Cu>Ni>Zn>Cr,and the average value of the comprehensive index RI of potential ecological risk was 237.74.Therefore,Cd and Zn are the main pollution elements of heavy metal in farmland soil in the study area,and there are certain differences of heavy metal contents in different sampling points.The heavy metal pollution of farmland soil in the study area is in a heavy pollution state,with medium ecological risk.The potential ecological risk of Cd pollution is relatively high,which needs more attention.