Aquatic environment

Effect of sorbed and desorbed Zn(II) on the growth of a green alga(Chlorella pyrenoidosa)


CHANG Guo-hua , CHEN Hao , CHEN Hai-liu , LI Wei , PAN Gang

DOI:

Received November 09, 2006,Revised January 10, 2007, Accepted , Available online

Volume 19,2007,Pages 1028-1031

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Toxic e ect of Zn(II) on a green alga (Chlorella pyrenoidosa) in the presence of sepiolite and kaolinite was investigated. The Zn-free clays were found to have a negative impact on the growth of C. pyrenoidosa in comparison with control samples (without adding any clay or Zn(II)). When Zn(II) was added, the algae in the presence of clays could be better survived than the control samples, which was actually caused by a decrease in Zn(II) concentration in the solution owing to the adsorption of Zn(II) on the clays. When the solution system was diluted, the growth of algae could be further inhibited as compared to that in a system which had the same initial Zn(II) concentration as in the diluted system. This in fact resulted from desorption of Zn(II) from the zinc-contaminated clays, although the e ect varied according to the di erent desorption capabilities of sepiolite and kaolinite. Therefore the adsorption and desorption processes of Zn(II) played an important part in its toxicity, and adsorption and desorption of pollutants on soils/sediments should be well considered in natural eco-environmental systems before their risk of toxicity to aquatic organisms was assessed objectively.

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