岷江下游11种杂草对重金属的富集特征

Accumulation Characteristics of Heavy Metals in Weed Plants from a Catchment of Lower Minjiang River

为了解岷江下游11种杂草不同部位(根、地上部)中5种重金属(As、Cd、Cu、Pb、Zn)的含量特征,选取五通桥段典型集水区,采用野外调查与室内分析相结合的方法,探讨该区杂草对重金属的富集和转运能力。结果表明,集水区土壤除Cd污染严重外,整体污染较轻。11种草本植物重金属含量为Zn>Pb>Cu>As>Cd,且根系都对As有明显的滞留效应。淡竹叶、巴天酸模、一点红、云南海金沙、铁芒箕、麦冬、绣球藤、酸浆草和蜈蚣草植株都存在地上部均有2种或者2种以上的重金属含量高于根部。11种杂草对重金属As富集能力都不强,富集系数和转运系数均小于1。铁芒箕和蜈蚣草对重金属Cd、Cu、Pb、Zn,淡竹叶、一点红、云南海金沙和酸浆草对Cd、Pb、Zn,麦冬对Cd和Cu,绣球藤对Cd和Zn的富集系数和转运系数都大于1,这些植物均具有超富集植物的一些重要特征,具有成为超富集植物的潜力。

Phytoremediation of soil heavy metals has drawn much attention. In this study, we investigated content and distribution of 5 heavy metals(As, Cd, Cu, Pb and Zn) in different parts of 11 weed plants collected from a typical catchment of Minjiang River in Wutongqiao District of Sichuan Province.(1)Soil p H and organic matter were 5.57 and 12.94 μg·g-1, respectively.(2)The soils were polluted heavily by Cd, but less by the others.(3)The content of heavy metals in weed plants was Zn>Pb>Cu>As>Cd, with As mainly accumulated in the roots.(4)The plants with two or more heavy metals higher in above-ground than in below-ground were Lophatherum gracile, Rumex patientia,Emilia sonchifolia, Lygodium yunnanense, Dicranopteris dichotoma, Ophiopogon Japonicus, Clematis montana, Oxalis corniculata and Pteris vittata.(5)All weed plants showed a weaker capacity to accumulate As, as indicated by As bio-accumulation and transfer index of lower than 1. Both bio-accumulation and transfer index were more than 1 for Cd, Cu, Pb, Zn in D. dichotoma and P. vittata, Cd, Pb and Zn in L.gracile, E. sonchifolia, L. yunnanense and O. corniculata, Cd and Cu in O. Japonicus, and Cd and Zn in C. montana. The results indicate that these weeds have the potential to rehabilitate heavy metal-polluted soils.