土壤钝化剂对黑土中铜的原位固定作用

采用盆栽试验研究3种钝化剂(粉煤灰、磷灰石和膨润土)对黑土中铜(Cu)的化学形态、生物积累和有效性的影响。结果表明:3种钝化剂能显著降低Cu污染黑土中水提取态(DW)、TCLP提取态和二乙基三胺五乙酸-三乙醇胺(DTPA-TEA)提取态Cu含量,其中以膨润土的效果最为明显;Tessier连续提取测定发现,3种钝化剂显著降低非残留态Cu(水溶态和交换态、碳酸盐结合态、铁锰氧化物结合态和有机结合态)含量(p<0.01),增加残留态Cu含量,表明3种钝化剂通过改变黑土中Cu的化学形态,降低了黑土中Cu的可淋失性和生物有效性;与对照相比,添加钝化剂能显著降低水稻地上部分的Cu含量(p<0.01),如在400Cu mg/kg处理的土壤上,添加2.5%的粉煤灰、磷灰石和膨润土使米粉中的Cu含量分别降低21.8%,22.7%和31.9%。土壤中可淋失态和生物有效态Cu的分析表明,钝化剂主要是通过改变土壤中Cu的化学形态,降低土壤中Cu的生物有效性,以降低Cu在水稻中的积累;试验表明,Cu污染土壤中施用钝化剂可以修复Cu污染,降低水稻Cu污染风险。

Situ Stablization of Copper in Black Soil by the Addition of Soil Amendments

Three amendments(coal fly ash,apatite,and bentonite) were applied to the two levels(200,400 mg/kg) of Cu-treated soil(udic agriboroll) at the rate of 1.5% and 2.5% in order to evaluate the in situ stabilization potential of soil amendments.The addition of three kinds of amendments to Cu-treated soil were found significantly to decrease the concentration of water-soluble,TCLP(toxicity characteristics leaching procedure)-extractable,and DTPA-extractable Cu.The most obvious effect was found in the soils amended with bentonite.The results showed that soil amendments significantly led to reduction of non-residual Cu(including water/exchangeable,carbonate,Fe-Mn oxides and organic-bound fractions)(p<0.01) and increased in residual Cu in soil.This indicated that three amendments changed the chemical forms of Cu in soil,which reduced the leachablity and bioavailability of Cu.Compared to non-amended soil treated with 400 Cu mg/kg,the addition of coal fly ash,apatite,and bentonite at the rate of 2.5% reduced the concentrations of Cu in grains by 21.8%,22.7% and 31.9%,respectively.The decreased uptake,accumulation of Cu by rice grown in amended soil was clearly related to the decrease of leachable and phytoavailable fraction of Cu.The possible mechanisms for in situ stabilization of Cu in soil was mainly through chemsorption of Cu associated with amendments and precipitation of insoluble Cu-like minerals.It is concluded that these amendments could effectively reduce the bioaccessibility and leachability of Cu in soil.