Accumulation of Heavy Metals by Some Aquatic Macrophytes in Estuarine Zone of River Tapi, Surat, Gujarat, India
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Aquatic plants are known to accumulate metals from their environment. The study focuses on assessment of heavy metal accumulation in certain aquatic macrophytesin comparison with water and sediments for phytoremediation. The aim of this study is to measure the concentrations of Cd, Co, Cu, Pb and Zn in four different species of aquatic macrophytes collected from estuarine zone of Tapi river near Surat city of Gujarat. Plants along with surface sediments and water were analyzed for Cd, Co, Cu, Pb and Zn contamination. The plant species selected were : Eichornia cressipes (Mart.)Solms-Loub (root and shoot) Persicaria glabra (Willd.)M.Gomez (root, stem and leaf) Pistia stratiotes L. (root and shoot) and Ceretophyllum demersum L. (whole plant). Samples were analyzed for heavy metals by AAS (Atomic Absorption Spectrophotometer). The greater accumulation of heavy metals was observed in the shoot of Pistia stratiotes. The lowest content was observed in Ceretophyllum demersum. Based on the concentration observed in the river's vegetation, the five heavy metals arranged in the descending order are : Pb > Cu > Zn > Co > Cd. The results of concentration of heavy metals in selected plants were compared with the standard, normal and critical toxicity range in plants. The detected value of Cd falls within normal range, while that of Co, Cu, Pb and Zn were within the critical range. However, Co and Cu showed the highest accumulation with alarming toxicity levels, which areconsidered as one of the most hazardous pollutants in river. Species like Persicaria glabra and Pistia stratiotes are also proposed as bioremediants, which are the most useful plant species in phytoremediation studies due to their ability to accumulate heavy metals in high concentration and their availability throughout the year.