重金属胁迫对三角褐指藻生长及叶绿素荧光特性的影响

利用调制式叶绿素荧光仪研究了不同浓度的重金属Cu2+、Zn2+、Cd2+胁迫不同时间(24、48、72和96 h)后,三角褐指藻叶绿素荧光特性的变化情况.测定的主要参数有:光系统II(PSII)的最大光能转化效率(Fv/Fm)、PSII的潜在活性(Fv/Fo)、PSII的实际光能转化效率(Yield=ΦPSII)、相对光合电子传递效率(rETR)、光化学淬灭(qP)和非光化学淬灭(NPQ).研究结果表明,重金属(Cu2+、Zn2+、Cd2+)胁迫下三角褐指藻的叶绿素荧光参数Fv/Fm、Fv/Fo、Yield、rETR和qP均明显降低,并且随着重金属离子浓度的增加,胁迫时间的延长,下降幅度逐步增大;NPQ先上升后下降或者逐渐上升;细胞密度和叶绿素含量也显著降低.对3种重金属离子的半抑制浓度(EC50)的计算结果表明,3种重金属毒性大小顺序为Cd2+> Cu2+> Zn2+.

Effects of heavy metals stress on growth and chlorophyll fluorescence of Phaeodactylum tricornutum

The modulate chlorophyll fluorescence kinetics of Phaeodactylum tricornutum under different heavy metal concentrations (Cu2+, Zn2+, Cd2+) and different time ( 24h, 48h, 72h and 96h) were investigated with Water-PAM chlorophyll fluorometer. The main parameters were determined in the present study including the maximal photochemical efficiency of PSII (Fv/Fm), the potential activity of PSII (Fv/Fo), the actual photochemical efficiency of PSII in the light (Yield=ΦPSII), the relative electron transport rate (rETR), the photochemical quenching (qP) and the non-photochemical quenching (NPQ). The results showed that the fluorescence parameters Fv/Fm, Fv/Fo, Yield, rETR and qP of P. tricornutum all were decreased under the of stress heavy metals (Cu2+, Zn2+, Cd2+). The changed degree above the parameters was increased with the increase of heavy metal concentration and time. NPQ first was increased then decreased or increased with the exposure time under heavy metal stress. The cell density and chlorophyll content were also decreased under heavy metal stress. The EC50 (the effective concentration causing 50% inhibition) values showed that the toxicity results can be expressed as Cu2+>Cd2+>Zn2+.