狗牙根根际土壤pH、有机质含量及重金属形态分布

pH,organic matter and speciation distribution ofheavy metals in rhizospheric soil ofCynodson dactylon

摘要:

以矿渣土和自然土为基质,对狗芽根进行盆栽实验,测量种植前后土壤pH值、有机质(SOM)及5种重金属Pb、Zn、Cd、Cr、Cu全量及弱酸提取态(F1)、可还原态(F2)、可氧化态(F3)、残渣态(F4)的形态含量。结果表明:与种植前相比,狗牙根种植100 d后土壤的pH均下降0.10~0.25个单位,变化率为1.31%~3.21%,有机质含量均上升,相对增加0.163%~1.854%。两种土壤的5种重金属含量不同,自然土为Zn＞Cu＞Pb＞Cr＞Cd,矿渣土为Zn＞Pb＞Cu＞Cr＞Cd。各重金属含量在狗牙根种植100 d后均下降,其中,自然土的5种重金属变化特征为Cd＞Zn＞Cr＞Pb＞Cu,而矿渣土的变化特征为Cd＞Cr＞Cu＞Pb＞Zn。5种重金属均以残渣态形态为主,弱酸提取态含量在各金属价态中占比均较低。4种存在形态都有变化,其中弱酸提取态、可还原态和可氧化态含量降低,而除Cd外,残渣态含量升高。综合分析表明,狗牙根是重金属污染土壤修复的较好的物种之一。

Abstract:

Cynodon dactylon plants were grown in pots filled with either slag soil or natural soil.Soil pH,organic matter (SOM),total content of Pb,Zn,Cd,Cr ,Cu,and different forms of heavy metals including extracted (F1),reducible (F2),oxidizable (F3) and residual (F4) forms were measured before and after culture.After 100 days,soil pH decreased by 0.10~0.25 unit (1.31%~3.21%),while soil organic matter content increased by 0.163%~1.854%.The natural and slag soil contained different levels of heavy metals,which followed an order of Zn＞Cu＞Pb＞Cr＞Cd in the natural soil,and an order of Zn＞Pb＞Cu＞Cr＞Cd in the slag soil.The content of all five heavy metals decreased after planting Cynodon dactylon for 100 days,with an order of Cd＞Zn＞Cr＞Pb＞Cu in the natural soil,and an order of Cd＞Cr＞Cu＞Pb＞Zn in the slag soil.All those five heavy metals were mainly in the form of residue,while the content of weak acid extraction state accounted for a relatively low proportion in each metal valence state.After planting Cynodon dactylon for 100 days,the contents of weak acid extracted state,reducible state and oxidizable state all decreased,while the residue state of all five metals except Cd increased.Our results showed that Cynodon dactylon is an ideal species for the remediation of heavy metal contaminated soil.