镧、铈及重金属元素铬、锌对竹叶眼子菜的毒害作用

Toxic Effects of Lanthanum, Cerium, Chromium and Zinc on Potamogeton Malaianus

研究了镧、铈及重金属元素铬、锌对高等沉水植物竹叶眼子菜(PotamogetonmalaianusMiq.)的毒害作用。结果表明,La3+,Ce3+,Zn2+在低浓度范围内,均能诱导叶绿素、蛋白质合成,但浓度过高时却对叶绿素、蛋白质起破坏作用;而Cr6+处理却使上述两指标随其浓度的升高逐渐降低。4种离子对竹叶眼子菜的保护酶系统存在不同的影响,低浓度条件下,诱导过氧化氢酶(CAT)、过氧化物酶(POD)活性升高,当污染加重时,这两种酶的活性却随处理浓度的升高逐渐下降;超氧化物歧化酶(SOD)活性变化与CAT、POD相反,它在低处理浓度情况下酶活下降,随处理浓度的加大酶活诱导上升,其活性变化趋势与·O-2产生速率正好相反。随4种离子处理浓度增高,MDA含量呈升高趋势,并与4种离子的处理浓度之间皆呈极显著正相关。4种离子的毒性强度依次为Cr6+>Ce3+>Zn2+>La3+。Cr6+对竹叶眼子菜的致死浓度为0 5～1mg·L-1,Ce3+,Zn2+为3～5mg·L-1,La3+为7～10mg·L-1。镧、铈同重金属元素铬、锌对竹叶眼子菜的毒害机制相似。

The toxic effects of rare earth elements such as lanthanum, cerium and heavy metal elements such as chromium, zinc on Potamogeton malaianus Miq. were studied. The results show that the contents of chlorophyll and soluble protein increase to a certain degree and then decrease under La^(3+), Ce^(3+), Zn^(2+) stress, while a constantly dropping tendency appears under Cr^(6+) stress. The four ions have different effects on protective enzyme systems of Potamogeton malaianus. They can induce rises of the activities of catalase (CAT) and peroxides (POD) at lower concentration, however, with the increasing concentration, and the activities decline. The change of SOD activity is exactly opposite to that of CAT activity and POD activity, it falls at first and rises later. An increasing tendency of MDA content appears with the increasing concentration. The toxicities of La^(3+), Zn^(2+), Ce^(3+) and Cr^(6+) become more serious in the order. The lethal concentration of Cr^(6+) to Potamogeton malaianus ranges from 0.5 to 1 mg·L^(-1), that of Ce^(3+) and Zn^(2+) ranges from 3 to 5 mg·L^(-1), and that of La^(3+) ranges from 7 to 10 mg·L^(-1). The toxic mechanism of La^(3+), Ce^(3+) is similar to that of Cr^(6+), Zn^(2+).