杨树落叶前后重金属元素内外迁移循环规律研究

Transferring and cycling of heavy metals in and out of poplar tree before and after its leaf fallen

供试元素在杨树各部位的含量和贮量为Ｚｎ＞Ｃｕ＞Ａｓ＞Ｐｂ＞Ｃｄ，并与环境中相应元素浓度呈正相关．落叶时元素的迁移主要发生在叶、枝、根和干之间，叶中８～４８％的Ａｓ、Ｚｎ迁移至主干的皮与材中，而Ｃｕ、Ｐｂ、Ｃｄ贮量均有增加，Ｚｎ、Ａｓ的内循环占总循环量的４０％，Ｃｄ、Ｐｂ、Ｃｕ表现为外循环，占总贮量的１７～２７％．同时分析了植物对土壤重金属污染的净化效率．

The transferring of heavy metals in poplar tree during its leaf fallen mainly occurs in the parts of leaf-branch, root and trunk. 8～48% of As and Zn in leaf is transferred to bark and timber, and the storage of Cu, Ph and Cd is increased. The internal cycling rate of As and Zn occupies 40%, and the external one of Cd, Ph and Cu occupies 17～27% of their storage. The purification efficiency of soil heavy metals by plants is also discussed in this paper.