城市地表水表层沉积物重金属污染特征与潜在生态风险评估:以永康市为例

Pollution Characteristics and Potential Ecological Risk of Heavy Metals in Urban Surface Water Sediments from Yongkang

为了解永康市城区地表水沉积物中重金属的污染特征,对永康市122个地表水表层沉积物中Ti、Cr、Mn、Co、Ni、Cu、Zn、As、Pb和Fe共10种重金属含量进行分析,解析重金属的来源并评价其潜在生态风险.结果表明,10种重金属的含量顺序为:Fe>Ti>Mn>Zn>Cr>Cu>Pb>Ni>As>Co,与金衢盆地土壤重金属元素背景值相比,除Ti外,其它9种重金属超标1.17~3.78倍;大多数重金属之间存在极显著相关性,说明大多数重金属之间存在相似污染来源,主要为五金制造等工业污染和交通污染;地积累指数评价结果显示,沉积物中重金属的污染程度依次为:Cr>Zn>Ni>Cu>Fe>As>Pb>Mn>Ti,Cr、Zn、Cu和Ni这4种元素部分样区达到中度污染或偏重污染;9种重金属潜在生态风险大小为:Cu>As>Ni>Cr>Pb>Co>Zn>Mn>Ti,Cu和As对综合生态风险指数平均贡献分别是22.84%和21.62%,其他7种元素平均贡献合计55.54%,综合潜在生态风险指数(RI)中89.34%为低生态风险,10.66%为中等生态风险.综合以上分析,永康市城区地表水沉积物重金属污染整体较轻,局部污染严重.

In order to understand the pollution characteristics of heavy metals in surface water sediments of Yongkang,we analyzed the concentrations of 10 heavy metals including Ti,Cr,Mn,Co,Ni,Cu,Zn,As,Pb and Fe in 122 sediment samples,explored the underlying source of heavy metals and then assessed the potential ecological risks of those metals by methods of the index of geoaccumulation and the potential ecological risk. The study results showed that: 10 heavy metal contents followed the order: Fe > Ti > Mn> Zn > Cr > Cu > Pb > Ni > As > Co,all heavy metals except for Ti were 1. 17 to 3. 78 times higher than those of Zhejiang JinhuaQuzhou basin natural soils background values; The concentrations of all heavy metals had a significantly correlation between each other,indicating that those heavy metals had similar sources of pollution,and it mainly came from industrial and vehicle pollutions; The pollution extent of heavy metals in sediments by geo-accumulation index( Igeo) followed the order: Cr > Zn > Ni > Cu > Fe > As > Pb >Mn > Ti,thereinto,Cr,Zn,Cu and Ni were moderately polluted or heavily polluted at some sampling sites; The potential ecological risk of 9 heavy metals in sediments were in the following order: Cu > As > Ni > Cr > Pb > Co > Zn > Mn > Ti,Cu and As contributed the most to the total potential ecological risk,accounting for 22. 84% and 21. 62%,others had a total of 55. 54%,through the ecological risk assessment,89. 34% of the potential ecological risk indexes( RI) were low and 10. 66% were higher. The contamination level of heavy metals in Yongkang was slight in total,but was heavy in local areas.