摘要
采用改进的BCR提取法结合ICP-MS测定厦门某国道旁土壤中重金属Fe、Mn、Cr、Cu、Ni、Pb、Zn、V、Sr的赋存形态,分析其形态与土壤性质之间的相关性,运用风险评价编码(RAC)法和次生相与原生相分布比值(RSP)法评估重金属生物有效性。结果表明:表层土壤重金属含量随路基距离的增加先降低后增高,在距路基0～1 m处含量最高,说明国道旁重金属受交通运输影响较大;垂直剖面土壤中Cu、Zn、Mn、Pb、Sr含量随土壤深度的增加而降低,其含量峰值主要出现在表层0～10 cm处。表层土壤中Pb、Cu、Zn、Mn、Sr的可提取态比例随距路基距离增加先降低后升高; Ni、Zn、Cu、Sr、Mn和V可提取态比例随垂直剖面深度增加而降低。元素各形态含量随元素总量的增加而增加,各形态间存在一定的相关性,重金属化学形态受土壤性质的影响。表层土壤中大部分重金属RAC值呈两端高中间低的趋势。其中Zn、Sr和Mn在距路基0～1m处风险较高,以交通活动来源为主;其余重金属在低风险范围内,但Cu受到交通活动、水泥厂的显著影响; Fe、V和Pb以自然来源为主。垂直剖面土壤重金属的RAC值呈整体下降趋势,Cu、Sr、Ni和Zn的高风险主要发生在表层,受到交通源的影响,其它重金属的风险低且以自然源为主。
Chemical species of heavy metals,including Fe,Mn,Cr,Cu,Ni,Pb,Zn,V and Sr,in surface and profile soil samples beside a national highway were investigated using a modified BCR extraction procedure combined with ICP-MS. The correlation between the chemical species of heavy metals and the soil properties was analyzed,and the bioavailabilities of heavy metals were evaluated by methods of the risk assessment code( RAC) and the ratio of secondary phase to primary phase( RSP). The results showed that concentrations of heavy metals in topsoil initially decreased and then increased with the distance from the road,and all the highest concentrations of heavy metals were found at 0-1 m away from the highway,indicating the significant effect of traffic. The concentrations of Cu,Zn,Mn,Pb and Sr in the vertical soil profile decreased with the increase of depth,and the peak values were mainly found at the 0 ～ 10 cm layer. The extractable proportions of Pb,Cu,Zn,Mn and Sr in topsoil were high at both ends and low in the middle of the distance from the roadbed,and the extractable proportions of Ni,Zn,Cu,Sr,Mn and V decreased downward along the soil profile. The concentrations of elements in different chemical forms correlated positively with their total amounts in soil,and there was a certain correlation,which is affected by the soil properties,among elemental concentrations of different chemical fractions. The RAC values of most heavy metals in the topsoil initially decreased and then increased with the distance from the road. The high risk of Zn,Sr and Mn occurred at 0-1 m from the road,implying the great effect of traffic. Cu was significantly influenced by the traffic and a cement plant,Fe,V and Pb derived mainly from natural sources. The RAC values of elements in the soil profile decreased with the depth. The soil profile had been polluted by Cu,Sr,Ni and Zn in different degrees with the high risk mainly occurred in the surface layer. The risks of other natural derived heavy metals were relatively low.
引文
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