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Comparative assessment of Azolla pinnata and Vallisneria spiralis in Hg removal from G.B. Pant Sagar of Singrauli Industrial region, India
(2009) Prabhat Kumar Rai; B.D. Tripathi
The aim of the present work was to monitor the Hg pollution in water and sediments of G.B. Pant Sagar located in Singrauli Industrial Region, India and to suggest the efficient aquatic plants for its phytoremediation. The study assessed the comparative potential of a free floating water fern Azolla pinnata and submerged aquatic macrophyte Vallisneria spiralis to purify waters polluted by Hg. Six days laboratory experiments have been conducted to mark the percentage removal of Hg at initial concentration of 0.1, 0.5, 1.0 and 3.0 mg L-1. The percentage removal of Hg was higher for A. pinnata (80-94%) than V. spiralis (70-84%). Likewise, the Hg accumulated in dry mass was much higher for A. pinnata and a high correlation (R2 = 0.91 for A. pinnata and 0.99 for V. spiralis) was obtained between applied Hg doses and accumulated amounts in biomass. A concentration dependent decrease in chlorophyll a, protein, RNA, DNA and nutrients (NO3- and PO43-) uptake was detected in A. pinnata and V. spiralis due to Hg toxicity. The decrease was more prominent in Azolla than Vallisneria. The results recommended the use of A. pinnata and V. spiralis to ameliorate the industrial effluents (thermal power, chlor-alkali and coal mine effluent) contaminated with Hg. © Springer Science+Business Media B.V. 2008.
Accumulation of chromium and zinc from aqueous solutions using water hyacinth (Eichhornia crassipes)
(2009) Virendra Kumar Mishra; B.D. Tripathi
Under present investigation Eichhornia crassipes (water hyacinth) has been tested for removal of two important heavy metals chromium (Cr) and zinc (Zn) from metal solution. This species was grown at four concentrations of Cr and Zn, i.e. 1.0, 5.0, 10.0 and 20.0 mg l-1 in single metal solution. This plant has performed extremely well in removing the Cr and Zn from their solution and was capable of removing up to 95% of zinc and 84% of chromium during 11 days incubation period. Removal of Cr at lower concentrations (1.0 and 5.0 mg l-1) was found harmless, without any symptom of toxicity but at 10.0 and 20.0 mg l-1, plants have shown some morphological symptoms of toxicity. On the other hand E. crassipes removed Zn safely at all the four concentrations, i.e. 1.0, 5.0, 10.0 and 20.0 mg l-1. In this case morphological symptoms of toxicity were not evident in the test plant. Biochemical parameters viz. protein, sugar and chlorophyll in experimental plants have shown a decreasing trend due to accumulation of Zn and Cr. Overall this methodology is safe for the removal of Zn and Cr and can be utilized at large scale after few further investigation. © 2008 Elsevier B.V. All rights reserved.

2009

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