广州郊区三类工业企业周边农田土壤重金属污染及生态风险评价

Heavy Metal Pollution and Ecological Risk Assessment of Farmland Soil Around Three Types of Industrial Enterprises in Guangzhou Suburb

【目的】以广州郊区典型的三类工业企业(电镀工业、印染纺织业和五矿稀土业)周边农田土壤为研究对象,评价重金属污染及其潜在生态风险程度,分析成因,为广州工业企业周边农田土壤重金属污染防治和修复提供参考依据。【方法】采集工业企业周边农田土壤共39个样品,采用污染负荷指数法分析土壤中重金属的污染程度,采用潜在生态风险指数法评价土壤重金属潜在生态风险程度。【结果】电镀工业和印染纺织业周边农田土壤重金属含量累积相对较多,综合重金属负荷等级为轻度污染;各类型周边土壤Cd、Hg存在较大潜在生态风险,其他重金属(As、Pb、Cr、Cu、Zn、Ni)为低风险;Cd潜在生态风险最高,风险系数均值在48.20-61.24之间。Hg潜在生态风险次之,风险系数均值在25.46-59.42之间,Zn潜在生态风险系数最小,潜在生态风险系数均值在1.13-2.73之间。各重金属潜在生态风险程度由强到弱依次为Cd>Hg>As>Cu>Ni>Pb>Cr>Zn;三家工业企业周边农田土壤状况处于轻微生态风险和中等生态风险,综合潜在生态风险程度依次为电镀工业>稀土工业>印染纺织业。【结论】工业活动所产生的重金属污染物会通过干湿沉降、污水灌溉、废弃物淋溶和粉尘等方式进入土壤,是农田重金属污染的重要来源。为抑制农田土壤向较重风险转变,提升农田土壤环境质量,确保农田土壤环境安全,应采取有效措施加强工业企业周边农田土壤环境监测和污染风险管控,尤其应加强对土壤Cd和Hg的污染治理。

【Objective】With farmland soil around three typical types of industrial enterprises(electroplating industry,printing and dyeing textile industry and minmetals rare earth industry)in Guangzhou suburb as the research object,the heavy metal pollution and potential ecological risk degree were evaluated and the causes were analyzed with a view to provide a reference basis for heavy metal pollution prevention and remediation of farmland soil around industrial enterprises in Guangzhou.【Method】A total of 39 soil samples were collected from farmland around the industrial enterprises.The pollution load index method was used to analyze the pollution degrees of heavy metals in the soil,and the potential ecological risk index method was used to evaluate the potential ecological risk degrees of heavy metals in the soil.【Result】The heavy metal content in the farmland soil around the electroplating industry and printing and dyeing textile industry was relatively high,and the comprehensive heavy metal load level was slightly polluted.Cd and Hg in the surrounding soils of different types had greater potential ecological risks,while other heavy metals(As,Pb,Cr,Cu,Zn,Ni)had lower ecological risks.Cd had the highest potential ecological risk,with the average risk coefficient ranging from 48.2 to 61.24.Hg had the second highest potential ecological risk,with the average risk coefficient ranging from 25.46 to 59.42.The potential ecological risk coefficient of Zn was the lowest,with the average value ranging from 1.13 to 2.73.The of potential ecological risks degree of heavy metals(from strong to weak)were showed as:Cd>Hg>As>Cu>Ni>Pb>Cr>Zn.The soil conditions of the farmlands around the three industrial enterprises were in slight ecological risk and medium ecological risk,and the comprehensive potential ecological risk degree ranked as:electroplating industry>rare earth industry>printing and dyeing textile industry.【Conclusion】Heavy metal pollutants from industrial activities will enter the soil through dry and wet deposition,sewage irrigation,waste leaching and dust,which are important sources of farmland heavy metal pollution.In order to restrain the transformation of farmland soil to more serious risks,improve the quality of farmland soil environment,and ensure the safety of farmland soil environment,effective measures should be taken to strengthen the monitoring of farmland soil environment around industrial enterprises and pollution risk control,especially to strengthen the soil Cd and Hg pollution control.