城市绿化树种香樟不同器官对土壤重金属的富集特征

为了了解不同土壤重金属浓度梯度及污染梯度下香樟不同器官的富集特征,测定了香樟树叶、树枝、树干和根际土壤中6种重金属元素(Cu、Zn、Pb、Cr、Mn、Ni)的含量.结果表明: 香樟地上部分重金属含量因器官、元素种类、根际土壤重金属浓度的不同而存在差异.香樟树叶和树枝重金属含量的大小顺序均为:Mn＞Zn＞Cu＞Cr＞Pb＞Ni,树干重金属含量为:Mn＞Zn＞Cr＞Pb＞Ni＞Cu.树叶对Mn的富集系数较高,为2.409;树干对Ni的富集系数较高,分别为树叶、树枝的8.6和17倍,且在不同土壤重金属浓度梯度下,香樟树干对Cu、Zn、Pb、Cr、Ni的富集系数均明显高于其他器官.香樟地上部分器官对Cu、Zn、Pb、Cr、Mn、Ni 6种重金属元素的综合富集能力大小顺序为:树叶＞树干＞树枝.随着土壤重金属污染等级的增加,香樟地上部分各器官的富集系数均逐渐降低.研究区域平均胸径为22 cm的单株香樟对重金属元素富集效能的大小顺序为:树叶＞树干＞树枝,其中树干对Cu、Zn、Pb、Cr、Ni的积累量均显著高于树叶和树枝.表明香樟对6种重金属元素均有一定的富集能力,并且树干对Pb和Ni的富集效能明显,分别占地上部分总积累量的82.7%和91.9%,能很好地富集并稳固土壤中的Pb和Ni,可作为修复治理土壤重金属污染的备选树种.

Characteristics of heavy metal enrichment efficiency in different organs of urban green tree Cinnamomum camphora.

The objective of this study was to explore the enrichment efficiency of heavy metals in Cinnamomum camphora organs under soil heavy metal concentration and pollution gradients. The compartments of the organs were leaf, branch, trunk, and rhizosphere soils, while the heavy metals under investigation were Cu, Zn, Pb, Cr, Mn and Ni. The results showed that the concentration of heavy metals was significantly different by organs, types of heavy metals, and concentration of rhizosphere soil heavy metals. Heavy metal concentration in leaf and branch followed the order of Mn ＞ Zn ＞ Cu ＞ Cr ＞ Pb ＞ Ni, while in trunks it followed the order of Mn ＞ Zn ＞ Cr ＞ Pb ＞ Ni ＞ Cu. The enrichment coefficient of Mn in leaf had the maximum of 2.409, and that of Ni in trunk was 7.6 and 16 times higher than that in leaf and branch, respectively. In addition, the enrichment coefficients of Cu, Zn, Pb, Cr and Ni in the truck were much higher than the other organs under diffe-rent soil heavy metal concentration gradients. The heavy metal enrichment capacities of Cu, Zn, Pb, Cr, Mn and Ni followed the order of leaf ＞ trunk ＞ branch. As the pollution gradient increased, the heavy metal enrichment coefficient decreased gradually. The heavy metal enrichment efficiency of C. camphora (DBH=22 cm) followed the order of leaf ＞ trunk ＞ branch, and the enrichment of Cu, Zn, Pb, Cr and Ni in trunk was significantly higher than in the other organs. The study showed that the C. camphora had a certain enrichment capacity to absorb heavy metals of Cu, Zn, Pb, Cr, Mn and Ni in soils. The enrichment efficiency of Pb and Ni in trunk was significantly higher than the other organs, which accounted for 82.7% and 91.9% of the total accumulation. Thus, C. camphora has the potential to be an alternative option in phytoremediation of heavy metal contaminated soils.