HgCl_2对铜绿微囊藻的急性毒性效应研究

Acute toxicity of HgCl_2 on the alga Microcystis aeruginosa

研究了铜绿微囊藻在HgCI_2胁迫下的生理指标变化。试验以藻OD_(680).值的变化及光合色素质量浓度为指标检测藻种生长状况,研究了不同质量浓度HgCl_2对微囊藻的毒性效应。结果表明,0.05～1.00mg/L的HgCI_2各处理组对藻种的生长均有抑制作用,且胁迫质量浓度与生长抑制间呈现正相关。随着HgCl_2质量浓度的升高,藻光合色素质量浓度降低。1 mg/L组抑制程度最显著,藻液由黄绿色变为白色,颜色变化明显,72 h生长抑制率为5076%,96 h叶绿素a合成抑制率为90.09%。胁迫96 h后,各处理组叶绿素和类胡萝卜素的比值均比对照组低,Hg对叶绿素的影响比类胡萝卜素更为显著。

This paper is to engage in a study of the toxic effects of HgCl/on the Microcystis aeruginosa and some experiments on the al- gae growth situation in hoping to find the changes of the OD value and photosynthetic pigments content in the algae ceils in the exponential phase. For this purpose, we have traced the characteristic absorption wavelengths and studied the inhibition to the micro algae growth which is pertaining to the Microcystis aeruginosa though analyzing the toxic effects of different concentrations of HgCl2 on the Microcystis aeruginosa. The results of our experiments show that 0.05 - 1.0 mg/L of HgCl2 would produce an inhibition effect on the growth of Microcystis aeruginosa in comparison with the contrast experiment. With the increase of the concentrations of HgCI2, the suppression ratio tends to increase correspondingly. On the other hand, the correlation of the growth with Hg2 ＋ concentrations of Microcystis aeruginosa proved to be significantly negative（ p 〈 0.05）. The most serious inhi- bition turned to be 1.0 mg/L HgCl2. In our experiments, we have detected that the Liquid algae（1.0 mg/L HgC12）changed its color of significantly（from the blue-green into yellowish-brown after 24 h exposured, and then it turned to yellow-white after 48 h exposured, and finally at the end of the experiment into white ）. However, no changes were found with the other groups from our macroscopic obser- vation. A brief summary can be made like this： its 72 h growth inhi- bition rate was 50.76%, 96 h of chlorophyll a synthesis inhibition rate was 90.09 %, while we could find the growth of micro algae through microscope, which indicate that the dead cells shape abnor- mally, with the cellular atrophy and not floating. The growth inhibi- tion rate of each exposure group was found to be 12.64%, 20.37%, 29.98 %, 50.70 % after the 72 h exposure. The result of the sum- mary of MANOVA on the OD680 of Microcystis aeruginosa exposed to different HgCl2 concentrations for different time lengths reveal that the stress time did more harm than the stress concentrations, though they may have the same effect on the photosynthetic pigments. However, the stress concentration did more affect than the stress time. Howev- er, when the concentration of HgCl2 was higher than 0. 1 mg/L, the chlorophyll a content of the algae would drop fleetly. The inhibition rate of chlorophyll a synthesis was found equal to 51.7 %, 64.47 %, 90.09%, with the Concentration of HgCl2 being 0.3 - 1 mg/L,after 96 h exposure. And after 96 h exposure, it would do more harm to the Chlorophyll than to Carotenoids.