Abstract
The impact of five heavy metals, copper (Cu), chromium (Cr), zinc (Zn), cadmium (Cd) and lead (Pb) at sub-lethal concentrations (0.05, 0.5, 5 μmol L?1) on the growth and photosynthesis of Chlorella vulgaris was studied through 96 h exposure experiments. The results showed that the effects of five metals on the growth of Chlorella vulgaris were dependent on both metal concentrations and exposure time. It was found that 5 μmol L-1 Cu, Cr, Zn, Cd and Pb significantly inhibited the growth of Chlorella vulgaris and the effect became weaker with the increase of exposure time. Different effects on chlorophyll fluorescence were found for different metals, among which Cu and Cr had an inhibiting effect and Zn and Cd promoted it. The effects of heavy metals on the growth and photosynthesis of Chlorella vulgaris are independent of each other; and they are not causally related.
Highlights
The impact of sub-lethal concentrations (0.05, 0.5, 5 μmol L−1) of the heavy metals copper (Cu), chromium (Cr), zinc (Zn), cadmium (Cd) and lead (Pb) on the growth and photosynthesis of Chlorella vulgaris was studied during 96 h exposure experiments
The effects of heavy metals on algae have received significant attention and have been extensively studied, the exposure concentrations in those studies were necessarily high to calculate LC50 or EC50 values, and little information is available for evaluating the effects of these metals at sub-lethal concentrations
There was no significant effect under the 0.05 μmol L−1 treatment when Cd or Zn was added to the medium (P > 0.05), though an inhibiting effect was found when the same concentration of Cu, Cr or Pb was added (P
Summary
The impact of sub-lethal concentrations (0.05, 0.5, 5 μmol L−1) of the heavy metals copper (Cu), chromium (Cr), zinc (Zn), cadmium (Cd) and lead (Pb) on the growth and photosynthesis of Chlorella vulgaris was studied during 96 h exposure experiments. The effects of heavy metal exposure upon algae manifest in suppressed cell division, inhibited growth rate, restrained enzyme activity and reduced photosynthesis [8,9,10]. Toxic effects of five heavy metals (Cu, Cr, Zn, Cd, Pb) at sub-lethal concentrations (0.05, 0.5 and 5 μmol L−1) on the growth and photosynthesis of Chlorella vulgaris were analyzed and compared, with the results intending to provide a more theoretical basis upon which to judge the toxic effects of heavy metals
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