不同重金属钝化材料对土壤胶体的影响

摘要

为明确钝化修复对土壤胶体中重金属分布的影响,以微米羟基磷灰石、纳米羟基磷灰石、磷灰石、生物质电厂灰和石灰为供试材料,采用室内培养方法研究5种钝化材料对土壤胶体含量及土壤胶体中重金属含量的影响.结果表明,与对照相比,石灰处理土壤胶体含量最大(119 g·kg-1,增幅为131％),其次为微米羟基磷灰石(118 g·kg-1,增幅为130％)、纳米羟基磷灰石(115 g·kg-1,增幅为124％)、磷灰石(82.9 g·kg-1,增幅为61.7％)和生物质电厂灰处理(80.6 g·kg-1,增幅为57.1％).磷灰石、生物质电厂灰和石灰处理显著降低了土壤胶体Cd含量,降幅为12.1％～24.0％;微米羟基磷灰石、纳米羟基磷灰石和磷灰石处理均显著降低土壤胶体中Cu含量,降幅为14.2％～20.5％.此外,5种钝化材料显著增加Cd和Cu在土壤胶体中的分配比例,其中添加w为1％的纳米羟基磷灰石(NHA)处理Cd分配百分比最大,为69.9％,增幅为154％;添加w为0.2％的石灰(LM)处理Cu分配百分比最大,为47.5％,增幅为135％.可见,钝化修复过程中可能会增加土壤胶体含量及胶体中重金属的分配比例.因此,在钝化修复过程中有必要增加对土壤胶体和土壤胶体中重金属含量的监测,加强对钝化修复过程的风险管控.%An in-lab incubation experiment was conducted to explore effects of soil amendments,i.e.micro-hydroxyapatire,nano-hydroxyapatite,apatite,ash from biomass burning power plants and lime,used to remedy heavy metals contaminated soils on content of soil colloid,and content and distribution of heavy metals in the colloid.Results show that the soil treated with lime was the highest in content of soil colloid (119 g · kg-1,131％),and then followed by the other four in a decreasing order,that is,the soils treated with micro-hydroxyapatite (118 g · kg-1,130％),with nano-hydroxyapatite (115 g · kg-1,124％),with apatite (82.9 g · kg-1,61.7％) and with power plant ash (80.6 g · kg-1,57.1％).The treatment with lime,power plant ash or apatite decreased the content of Cd in the colloid significantly or with a rate ranging from 12.1％ to 24.0％,while the treatment with apatite,micro-hydroxyapatite ornano-hydroxyapatite decreased the content of Cu in the colloid significantly or with a rate ranging from 14.2％ to 20.5％.Besides,the use of any of the five soil amendments increased the distribution ratios of Cd and Cu in the soil colloid,especially the use of nano-hydroxyapatite with an application rate being 1％,which increased the distribution ratio of Cd,up to 69.9％ or by 154％,and the use of lime which increased the distribution ratio of Cu in soil colloid up to 47.5％ or by 135％.The findings of this study demonstrate that the use of soil amendments to remedy heavy metals contaminated soils may increase the content of soil colloid and distribution ratios of heavy metals in the colloid.It is necessary to monitor the content of soil colloid and the content of heavy metals in the soil colloid during soil remediation,so as to intensify risk management of the soil remediation orocess.