Available online at www.sciencedirect.com Journal of Hazardous Materials 158 (2008) 359–365 Screening of native plants and algae growing on fly-ash affected areas near National Thermal Power Corporation, Tanda, Uttar Pradesh, India for accumulation of toxic heavy metals S. Dwivedi, S. Srivastava, S. Mishra, B. Dixit, A. Kumar, R.D. Tripathi ∗ Ecotoxicology and Bioremediation Group, National Botanical Research Institute, Rana Pratap Marg, Lucknow 226001, India Received 20 November 2007; received in revised form 23 January 2008; accepted 23 January 2008 Available online 2 February 2008 Abstract The present investigation was carried out to screen native plants growing in fly-ash (FA) contaminated areas near National Thermal Power Corporation, Tanda, Uttar Pradesh, India with a view to using them for the eco-restoration of the area. A total number of 17 plants (9 aquatic, 6 terrestrial and 2 algal species) were collected and screened for heavy metal (Fe, Zn, Cu, Mo, B, Si, Al, Cr, Pb, Cd, Hg and As) accumulation. Differential accumulation of various heavy metals by different species of plants was observed. Hydrilla verticillata was found to be the most efficient metal accumulator among 9 aquatic plants, Eclipta alba among 6 terrestrial plants and Phormedium papyraceum between 2 algal species. In general, the maximum levels of most metals were found in terrestrial plants while the lowest in algal species. However, translocation of the metals from root to shoot was found to be higher in aquatic plants than terrestrial ones. These results suggest that various aquatic, terrestrial and algal species of plants may be used in a synergistic way to remediate and restore the FA contaminated areas. © 2008 Published by Elsevier B.V. Keywords: Algae; Aquatic plants; Fly-ash; Phytoremediation; Terrestrial plants 1. Introduction Fly-ash (FA), a resultant of combustion of coal at high tem- perature, has been regarded as a problematic solid waste [1]. The global generation of coal FA is estimated to be above 600 million tonnes [2]. In India only, annual production of FA is about 120 million tonnes by 82 power plants, which is expected to cross the figure of 150 million tonnes in the coming years [3]. Since, Indian coal is rich in ash content [4]; it has posed seri- ous disposal and ecological problems and caused large tracts of arable and non-arable land to become unusable. Dumped FA may also adversely affect the environment by mobilization of its fine particles and hazardous constituents contaminating air, water, soil and vegetation [5]. Despite negative environmental impact of FA, coal continues to be a major source of power production in India and therefore FA disposal is a major envi- ∗ Corresponding author. Tel.: +91 522 2205831–35x222; fax: +91 522 2205836/39. E-mail address: tripathi rd@rediffmail.com (R.D. Tripathi). ronmental issue. In recent times, attempts have been made to utilize FA for various purposes, such as for manufacturing of bricks [6] and as a soil amender [7]. However, these practices utilize only limited proportion (<15%) of FA and huge amounts remains unutilized. Fly-ash is largely alkaline in nature and contains many essen- tial elements like S, B, Ca, Mg, Fe, Cu, Zn, Mn and P along with toxic metals, such as Cr, Pb, Hg, Ni, As and Cd [8,9]. FA appli- cation to soil at a low rate has been reported to promote the growth of the plants [10] through improvement of soil conduc- tivity, organic carbon, microbial activity [6], soil porosity and water holding capacity [11]. This raises the possibility of using phytoremediation as an applicable technology to remediate the FA contaminated areas as well as to restore these for beneficial purposes [12]. The technology uses plants to remove toxic ele- ments from the contaminated sites through their accumulation in harvestable shoot parts (i.e. phytoextraction) or to immobi- lize metals in soils or sediments by root uptake, adsorption onto roots or precipitation in the rhizosphere (i.e. phytostabilization) [13]. A number of terrestrial plants particularly the members of Brassicaceae have been found to be good accumulator of 0304-3894/$ – see front matter © 2008 Published by Elsevier B.V. doi:10.1016/j.jhazmat.2008.01.081