Abstract

Floating ferns of the genus Salvinia have great potential for phytoremediation of heavy metals. To date, the effect of essential metals on the accumulation and transport of toxic metals by aquatic ferns has not been suitably established. The aim of this study was to compare the ability of floating leaves of Salvinia minima and Salvinia rotundifolia species to accumulate Cr from Cr(VI solutions containing very low (0.02 mg L⁻¹) and low (5 mg L⁻¹) Zn concentrations. After 7-day metal-exposure period, results showed that Zn increased Cr accumulation in S. minima leaves whereas in S. rotundifolia decreased significantly. Contrarily Zn accumulation did not show great differences between species. This fact may indicate that Zn interfere Cr(VI) uptake by S. rotundifolia. Bioconcentration factor (BCF) and translocation factor (TF) were affected differently by Zn in both Salvinia species. Membrane stability index (MSI) of both Salvinia species was decreased significantly by 5 mg L⁻¹ Zn concentration. Zn ions also increased hydrogen peroxide accumulation in fronds of Salvinia species. Total thiols (TT), non-protein thiols (NPT) and protein-bound thiols (PBT) were differentially affected by Cr(VI) and Zn ions. This study provides evidences on the involvement of different mechanisms against Cr(VI)/Zn toxicity in S. minima and S rotundifolia species.

摘要

Salvinia属的漂浮蕨具有重金属植物修复的巨大潜力。迄今为止，尚未适当地确定必需金属对水生蕨类植物积累和运输有毒金属的影响。本研究的目的是比较极小Salvinia和极小Salvinia rotundifolia种类的浮叶从Cr（VI溶液中的Zn浓度非常低（0.02 mg L ^-1）和低（5 mg L ^-1）的溶液中积累Cr的能力。经过7天的金属暴露时间后，结果表明锌增加了小叶链霉菌叶片中Cr的积累，而圆叶链球菌中明显减少。相反，锌的积累在种间没有显示出很大的差异。这一事实可能表明，锌会干扰圆叶链球菌对Cr（VI）的吸收。在两个萨尔维尼亚物种中，锌对生物富集因子（BCF）和转运因子（TF）的影响不同。两种Salvinia的膜稳定性指数（MSI）显着降低了5 mg L ^-1 Zn浓度。锌离子还增加了萨尔维尼亚叶片中的过氧化氢积累种类。Cr（VI）和Zn离子对总硫醇（TT），非蛋白硫醇（NPT）和与蛋白结合的硫醇（PBT）的影响不同。这项研究提供了证据证明S. minima和S rotundifolia物种对Cr（VI）/ Zn毒性具有不同的作用机制。