砷浓度、形态及碳酸氢盐对蜈蚣草吸收砷的影响

为了探讨超富集植物蜈蚣草在处理高砷地下水方面的可行性,研究了水培条件下砷的浓度、形态和碳酸氢盐(HCO-3)对超富集植物蜈蚣草吸收砷的影响。实验中使用了浓度为0.1～100mg·L-1的As(III)和As(V)溶液。HCO-3处理中,HCO-3浓度范围为0.5～20mmol·L-1,As(III)或As(V)的浓度为5mg·L-1。结果表明,在水培条件下,蜈蚣草具有明显的耐高砷特征。当介质砷含量高达100mg·L-1时,砷的去除率可达到80%,且对As(III)的吸收效率高于As(V)。植物体内砷形态研究表明,蜈蚣草体内2种形态砷的含量与外源砷形态有一定的关系,As(V)处理条件下,植物体中的As(V)比例较As(III)处理高。高浓度的HCO-3(20mmol·L-1)处理对蜈蚣草地上部分生物量没有明显影响,但是抑制了地下部分的生长,并且对砷的吸收表现出明显的抑制作用。

Effects of Arsenic Concentration, Species and Bicarbonate on Arsenic Uptake by Hyperaccumulator Pteris vittata L.

Arsenic concentration, species and bicarbonate concentration on arsenic uptake were investigated to evaluate the feasibility of arsenic removal from high arsenic groundwater using hyperaccumulator Pteris vittata L. by hydroponic experiments. As(III) or As(V) solutions at concentrations between 0.1 and 100 mg·L^-1 were used. In HCO₃^- treatments, the concentration of HCO₃^- in solutions was in the range of 0.5 and 20 mmol·L^-1 with 5.0 mg·L^-1 As(III) or As(V). Results showed that Pteris vittata L. could tolerate high-concentration arsenic. When As concentration was up to 100 mg·L^-1, removal efficiency of As by Pteris vittata L. reached 80%. Arsenic uptake of Pteris vittata L. was higher in
As(III) treatments than that in As(V) treatments. Contents of As species in plants were in association with that in solution. The ratio of As(V) to total As in plants of As(V) treatments was higher than that of As(III) treatments. High concentrations of HCO₃ ^- (20 mmol·L^-1) had no significant effect on root biomass, while it inhibited the growth of fronds. Moreover, high concentrations of HCO₃ ^-resulted in great suppression in plant As uptake, regardless of As(III) and As(V) treatments.