Cd^2+对紫球藻生长及光化学活性的影响

EFFECTS OF CD^(2+) STRESS ON THE GROWTH AND PHOTOCHEMICAL ACTIVITY OF PORPHYRIDIUM PURPUREUM

以紫球藻(Porphyridium purpureum)为供试材料,研究了5个不同浓度的Cd^(2+)对紫球藻的细胞密度、叶绿素a含量、藻红蛋白含量及ATP含量的影响,以及对紫球藻的最大光量子产额(Fv/Fm)、实际光量子产额(YII)、相对电子传递效率(ETR)及非光化学淬灭(NPQ)的影响,探讨了各荧光参数在不同浓度的Cd^(2+)胁迫下的变化规律。研究结果表明,在Cd^(2+)胁迫的6d内,紫球藻的生长速度显著下降,且Cd^(2+)的浓度越高,生长速度下降越快;Cd^(2+)胁迫显著的减少叶绿素a、藻红蛋白及ATP含量,且浓度越高,减少的幅度越大;在Cd^(2+)浓度低于200μmol/L时,紫球藻的叶绿素荧光参数Fv/Fm、YII及ETR呈现先下降后上升的趋势,而且随着胁迫时间的延长,下降幅度逐步增大;NPQ在低浓度下(<200μmol/L)呈现显著上升趋势,高浓度下(>500μmol/L)呈现显著下降趋势。因此,水体中浓度超过50μmol/L的Cd^(2+)就会显著影响紫球藻的生长及光化学活性,水生环境中不断累积的Cd^(2+)将会对紫球藻的生态平衡产生影响。

This study investigated the effects of Cd^2+on the biomass,chlorophyll a content,phycoerythrin content and ATP content,the maximum quantum yield of PSII(Fv/Fm),the effective photochemical yield of PSII(YII),the relative electron transfer rate(ETR)and non-photochemical fluorescence of quenching(NPQ)of the Porphyridium purpureum.The results showed that the growth rate of P.purpureum decreased significantly by the stress of Cd^2+in a dosage-dependent pattern.The content of chlorophyll a,phycoerythrin and ATP decreased significantly by Cd^2+stress with a dose-dependent way.The chlorophyll fluorescence parameters(Fv/Fm,YII and ETR)under Cd^2+stress were significantly lower than those of the control groups and decreased rapidly with increased Cd2+concentration.NPQ value increased significantly at low Cd^2+(<200μmol/L)and decreased significantly at high Cd^2+(>500μmol/L).Therefore,the gorwth and phtochemical activities of Porphyridium purpureum would be significantly affected by the concentration of the Cd^2+above 5μmol/L and the accumulation of Cd^2+would have an impact on the ecological balance of the Porphyridium purpureum in aquatic environment.