Chapter 5 - Phytorestoration of abandoned ash-ponds by native algal strains

Abstract

The present study was carried out to screen diversity of native algal strains growing in the vicinity of heavy metal polluted ponds and ditches near National Thermal Power Corporation, Kanti, Bihar, India with a view to use them for the phytorestoration of the area. The present data revealed a total of 28 species of algal strains, which constitutes 12 blue-green algae (BGA), 9 green algae (GA), and 7 diatom species. Overall, nine dominant in terms of high biomass producing algal strains were selected and evaluated for metal uptake potential viz. Anabaena, Phormidium, and Oscillatoria from BGA; Hydrodictyon, Oedogonium, and Spirogyra from GA including Cymbella and Navicula from diatoms. All the selected algal strains were analyzed for seven heavy metals viz. Fe, Cu, Zn, Ni, Cr, Cd, and As accumulation. Differential accumulation of various heavy metals by different algal species was observed. Among these, the maximum accumulation of heavy metals was shown by Anabaena followed by Phormidium, Nostoc, Spirogyra, Navicula, Oscillatoria, Oedogonium, Hydrodictyon, and Cymbella species. Most of the algal species showed a high population density with better growth performance on fly ash polluted sites without any visible toxicity symptoms. Moreover, the dominant BGA species like Anabaena and Nostoc play an important role in the maintenance of soil fertility by the addition of organic matter, soil moisture, and nitrogen fixation. It indicates the suitability of these algal floras for the ecological restoration of the metal-polluted water bodies with the recovery of valuable metals.