重金属Cd-Cu复合污染对苍耳生长及叶绿素荧光特性的影响

Effects of Heavy Metal Cd-Cu Combined Pollution on the Growth and Fluorescence Characteristics of Xanthium sibiricum Patrin ex Widder

采用盆栽土培法研究Cd(0～50mg/kg)单一污染及与Cu(0～500mg/kg)复合污染对苍耳(Xanthium sibiricum Patrin ex Widder)生长及叶绿素荧光特性的影响。生长特性研究结果表明:Cd(<30mg/kg)与Cu(<50mg/kg)复合污染时,生长指标(生物量、根系表面积及株高)显著大于单一Cu或Cd污染下的生长指标,且随着Cd与Cu复合浓度的增加而逐渐下降;Cd与Cu复合污染在低浓度下表现为拮抗效应,高浓度下表现为协同作用。生理特性研究结果表明:与单一Cd污染相比,Cd(<50mg/kg)与Cu(<50mg/kg)复合污染时,最大荧光产量(Fm)、光化学效率(Fv/Fm)及电子传递速率(ETR)明显较大,而初始荧光(Fo)明显较小(p<0.05),表明Cu能一定程度上缓解Cd对苍耳的毒害作用。苍耳对重金属的富集及转移系数计算结果表明:与单一Cd污染相比,Cd(<15mg/kg)与Cu(<100mg/kg)复合污染时,苍耳对Cd的富集系数明显较大,表明Cu能有效促进苍耳对Cd的富集;Cd(<50mg/kg)与Cu(<100mg/kg)复合污染时,苍耳对Cd的转移系数明显较小,表明Cu不能有效促进苍耳把Cd从地下部转移到地上部。苍耳可以考虑作为修复Cd-Cu复合污染的候选植物种之一。

Effect of Cd(0-50mg/kg)single pollution and Cu(0-500mg/kg)combined pollution on the growth and fluorescence characteristics of Xanthium sibiricum Patrin ex Widder was studied by potted soil culture method.Study of the growth characteristics shows that when Cd(<30mg/kg)and Cu(<50mg/kg)are combined,the growth indexes(biomass,root surface area and plant height)are significantly greater than that under single Cu or Cd pollution,and the indexes gradually decrease with the increase of the complex concentration of Cd and Cu;the combined pollu-tion of Cd and Cu shows antagonistic effect at low concentration,and synergistic effect at high concentration.The study results of the physiological characteristics show that when Cd(<50mg/kg)and Cu(<50mg/kg)are combined,the maximum fluorescence yield(Fm),photochemical efficiency(Fv/Fm)and electron transfer rate(ETR)are significantly larger than those of single Cd contamination,and the initial fluorescence(Fo)is significantly smaller(p<0.05),indicating that Cu can alleviate the toxic effects of Cd on Xanthium sibiricum Patrin ex Widder.Compared with single Cd pollution,when Cd(<15mg/kg)and Cu(<100mg/kg)are combined,the enrichment coefficient of Cd is significantly larger,indicating that Cu can effectively promote the enrichment of Cd by Xanthium sibiricum Patrin ex Widder;when Cd(<50mg/kg)and Cu(<100mg/kg)are combined,the transfer coefficient of Cd is significantly smaller,indicating that Cu can not effectively promote the transfer of Cd from the underground to the ground.Xanthium sibiricum Patrin ex Widder can be considered as one of the candidate plant species for repairing CdCu complex pollution.