铜、砷单一及复合污染对黑藻的毒性效应

摘要

The effects of Cu and As(Ⅴ) and their compound pollution on the growth, bioaccumulation capacity and superoxide dismutase ( SOD) activities of Hydrilla verticillata ( L. F. ) Royle ( H. Verticillata) were studied by indoor simulation experimentation. The results showed that the 4 d-EC50 of Cu and As(Ⅴ) for H. Verticillata was 2 and 12 μmol/L, respectively. Cu was more toxic to this plant than As(Ⅴ). Compared with the control treatment (0 μmol/L Cu + 5 μmol/L As(Ⅴ)), the growth of the plant was promoted when exposed to lower concentrations of Cu ( < 2 μmol/L) + 5 μmol/L As(Ⅴ) , and the accumulation of total arsenic as well as As( Ⅲ ) (which accounted for most of the total arsenic) also dramatically decreased. Moreover, the addition of As(Ⅴ) also inhibited Cu accumulation and increased SOD activities of H. Verticillata, as compared with the Cu single treatment. As a result, it appeared to have an antagonistic effect for lower concentrations of Cu +5 μmol/L As(Ⅴ). Although As and Cu accumulation were markedly inhibited at higher Cu concentrations ( ≤2 μmol/L) + 5μmol/L As(Ⅴ) in comparison with the single treatment, the growth of the plant was considerably inhibited. Additionally, SOD activities of the plant were strongly reduced (P < 0.05) by the compound pollution of Cu + As(Ⅴ) as compared with the single pollution. Therefore, higherconcentrations of Cu + 5 μmol/L As ( V ) presented a synergistic effect on H. Verticillata. In summary, this plant has high potential to be used for the phytoremediation of waters contaminated by Cu and As and their compounds at relatively low concentrations.%通过室内模拟试验,研究了铜(Cu)、五价砷[As(Ⅴ)]单一及复合污染对黑藻[Hydrilla verticillata(L.f.)Royle]生长、富集Cu和As的能力以及对超氧化物歧化酶(SOD)活性的影响.毒性测试结果表明,Cu和As(Ⅴ)对黑藻的4 d-EC50分别为2和12 μmol/L,单一Cu对黑藻的毒性远高于As(Ⅴ).复合污染试验结果表明,对于5μmol/L As(V)处理组,低浓度Cu[c(Cu)＜2μmol/L]的加入,促进了植物生长,降低了植物体内的As总量[w(As)],同时降低了植物体中占主要部分的三价砷的含量(w[As(Ⅲ)]).对于Cu处理组,As(Ⅴ)的加入同样抑制了黑藻对Cu的富集,SOD活性也高于单一Cu处理,可见在低浓度Cu处理下,Cu和As(V)之间存在拮抗作用；而高浓度Cu[c(Cu)≥2 μmol/L]的加入,虽然植物对Cu和As(Ⅴ)的富集与单一Cu和As(V)处理相比均显著降低,但植物生长受到抑制,SOD活性与单一处理相比也显著降低(P＜0.05),因此高浓度Cu处理下,二者对黑藻毒性起协同作用.总之,黑藻具有应用于处理低浓度Cu和As(V)单一及复合污染水体的潜力.