铜锌对铜钱草净化水中氮磷及抗氧化酶活性的影响

Effects of Zinc and Copper Ions on the Removal of TN and TP in Water by Hydrocotyle vulgaris and on the Antioxidant Enzyme Activities in Their Leaves

以铜钱草为供试植物,通过水培试验研究在铜、锌分别胁迫下,铜钱草净化水中氮磷的效果及其叶片中叶绿素、丙二醛、抗氧化酶活性的变化.结果表明,经过20天的培养,低浓度的铜锌(0.5、1.0mg/L的铜、锌和1.5mg/L的铜)提高了植株净化氮、磷的效果.低浓度的铜、锌处理(尤其是1.0mg/L)促使植株叶片中叶绿素总量、叶绿素а/β明显增加,且抗氧化酶活性增强导致丙二醛含量维持较低水平,说明植株叶绿体微结构完善、细胞内环境稳定,有利于植株对氮、磷的净化;与对照组相比,2.0mg/L锌处理明显降低了铜钱草对氮、磷的去除效果.主要缘于锌的胁迫通过降低叶绿素总量、叶绿素а/β值,且抑制抗氧化酶活性导致丙二醛含量明显高于其他各组(8.40μmol/gFW),使植株内环境出现氧化胁迫、生长受损所致.研究表明,铜钱草对铜、锌具有一定的耐受力,较低浓度的铜、锌有助于其对水体中的氮、磷的去除.

Using Hydrocotyle vulgaris as experimental plant, through the hydroponic experiments, the TN and TP removal capacity of plants and the variation of some physiological characteristics in their leaves including the chlorophyll contents, the MDA contents and the activities of antioxidant enzymes under the stress of Zn and Cu were investigated. The results indicated that Zn （0.5 and 1.0 mg/L） and Cu （0.5, 1.0 and 1.5 mg/L） increased the TN or TP removal capacities of Hydrocotyle vulgaris. The chlorophyll contents and the ratio of chlorophyll а to chlorophyll β in the leaves obviously increased after the plants were treated with Zn （1.0 mg/L） or Cu （1.0 mg/L）. Moreover, the levels of MDA were low due to the enhancement of the activities of antioxidant enzymes. All indicated that the micro-structure of chlorophyll grew perfectly and the innerenvironment of cells kept stable, which benefited the TN and TP removal abilities of Hydrocotyle vulgaris; However, besides of the decrease of the chlorophyll contents and the ratio of chlorophyll a to chlorophyll b, the treatment of 2.0 mg/L Zn in water resulted in the highest level of MDA （8.40μmol/gFW） than that in other treatment groups. It inferred that oxidative damage in the plants was adverse to the growth and the TN and TP removal of Hydrocotyle vulgaris. Results also indicated that Hydrocotyle vulgaris, at an extent, has tolerance to Zn and Cu, and the suitable contents of Zn and Cu benefit the TN and TP removal abilities of the plant.