菹草在低浓度含铜尾水净化过程中的毒性研究

Tolerance of Potamogeton crispus to Toxicity in Purifying Low Concentration Copper Containing Tailwater

将菹草(Potamogeton crispus)种植于不同浓度的含游离态(CuSO4)和螯合态(EDTA-Cu)铜离子模拟尾水中,定期观测菹草在不同浓度、不同形态含铜尾水中的生长状况,并用水下饱和脉冲叶绿素荧光仪测定菹草光合作用PSⅡ有效荧光产量(Fv/Fm)、光化学荧光淬灭系数(qP)和非光化学荧光淬灭系数(qN)等指标,以研究菹草在低浓度含铜尾水净化过程中的生态效应。结果表明,菹草对铜离子有吸附或富集作用,且对CuSO4的吸附或富集能力大于EDTA-Cu。CuSO4对菹草的毒性作用小,且对菹草生长有一定的促进作用;随着铜离子浓度(0.01、0.3、0.5和1.0 mg·L-1)的递增,CuSO4各试验组菹草叶片数增加量分别是对照组的292.5%、390.0%、155.0%和45.0%。而EDTA-Cu在试验浓度范围内对菹草的生长影响较小,毒性作用不明显。随游离态和螯合态铜离子浓度的提高,相对光合电子传递速率(RET)、Fv/Fm、qP和qN变化明显,表明一定浓度的铜离子增强了菹草的光电子传递速率和份额,铜离子对PSⅡ反应中心的毒性作用较小,可以促进其光合作用。

In simulated tailwaters different in concentration of CuSO4 and EDTA-Cu, Potamogeton crispus was planted.Growth of the plants was monitored regularly and PSⅡ effective fluorescence yield （Fv / Fm ）, photochemical quenching（qP ） and non-photochemical quenching （qN） of photosynthesis of the plants were determined with a underwater saturationpulse chlorophyll fluorescence analyzer （DIVING-PAM） to explore ecological response of the plants in purifying low con-centration copper containing tailwater. Results show that P. crispus could adsorb and enrich copper ions, the capacity of ab-sorbing CuSO4 is higher than of EDTA-Cu. CuSO4 was less toxic to the plant and more or less conducive to the growth ofthe plant. In CuSO4 treatments when CuSO4 concentration was 0. 01, 0. 3, 0. 5 and 1. 0 mg·L-1, the number of leavesper plant was 292. 5%, 390. 0%, 155. 0% and 45. 0%, as many as that in the control, respectively. However, EDTA-Cudid not have much effect or much toxicity on growth of the plant when it was within the range of concentrations in the test.With rising concentration of CuSO4 and EDTA-Cu, RET, Fv / Fm, qP and qN varied significantly indicating that a certainconcentration of copper ion can increase the transfer rate and share of photoelectrons and promote photosynthesis and isquite low in toxicity to PSⅡ reaction center of the plants as well.