5种栎树幼苗对铅锌尾矿砂的耐性与植被恢复前景

Tolerance and vegetation restoration prospect of seedlings of five oak species for Pb/Zn mine tailing

通过盆栽试验,评价栎属植物在铅锌尾矿中的生长响应及植被恢复前景.分析比较了覆瓦栎、猩红栎、樱皮栎、舒玛栎和白栎5种栎树幼苗在铅锌矿砂中生长30个月后的生物量、根系形态及其对营养元素和重金属的吸收及转移特征.结果表明:5种栎树在矿砂中均能生长,其中,猩红栎和白栎的生物量较对照有下降趋势,其他3种栎树的生长与对照相比无显著差异;栎树根系生物量均较对照有不同程度增加(猩红栎除外),且仅猩红栎侧根形态学参数较对照有所减少.重金属胁迫下,栎树根系和茎中营养元素浓度较对照无显著变化.5种栎树体内重金属浓度均较低,且其生物富集系数和转移系数均小于1.但樱皮栎叶片和茎中Cd浓度分别为22.4和15.1 mg·kg^-1,转移系数为2.3,显著高于其他4种栎树.除猩红栎以外,其他参试栎树均可作为有潜力的污染土壤修复树种.其中舒玛栎的耐性较高、生物富集系数和转移系数较低,是适合在尾矿区造林和生态修复的优选树种.

A pot experiment was conducted to evaluate the growth response and vegetation restoration prospect of seedlings of five oak species for the phytoremediation of lead/zinc(Pb/Zn)mine tailings.Seedlings of Quercus imbricaria,Q.coccinea,Q.pagoda,Q.shumardii,Q.fabri were transplanted into pots containing Pb/Zn mine tailings to comparatively examine their biomass,root morphology,absorption and transfer characteristics of nutrient elements and heavy metals 30 months later.The results showed that all the seedlings could survive in the Pb/Zn tailings after 30 months.The biomass of Q.coccinea and Q.fabri decreased in Pb/Zn tailings compared with the control,while no significant difference were found for other three species.Compared with the control,root biomass was increased to some extent in Pb/Zn tailings except Q.coccinea.The lateral root morphological parameters were reduced only for Q.coccinea.Under heavy metal stress,nutrient concentrations of root and stem of oak seedlings did not change compared with the control.Generally,the concentrations of heavy metals in plant tissues were low,and the values of bioconcentration factor(BCF)and translocation factor(TF)were less than 1.Q.pagoda could accumulate more Cd,with concentrations of 22.4 and 15.1 mg·kg^-1 in leaf and stem,respectively,and could translocate more Cd from root to shoot with TF of 2.3.Our results suggested that the seedlings of tested oak species could be used as the potential species for contaminated soil.Q.shumardii had the highest tole-rance with a low BCF and TF,implying that they were better potential candidates for afforestation and ecological restoration of mine tailings.