Phytoextraction of Heavy Metals by Some Aquatic Macrophytes in Fresh Water Stretch of River Tapi at Surat City, Gujarat, India

The study was conducted to measure the concentrations of Cd, Co, Cu, Pb and Zn in five different species of aquatic macrophytes collected from fresh water stretch of Tapi river at 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), Hydrilla verticillata (L. f. ) Royle (whole plant), 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 root of Pistia stratiotes. The lowest content was observed in the stem of Eichornia cressipes. Based on the concentration observed in the river's vegetation, the five heavy metals arranged in the descending order are Zn greater than Cu greater than Pb greater than Co greater than 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 are considered as one of the most hazardous pollutants in river. Species like Hydrilla verticillata, Persicaria glabra and Pistia stratiotes are also proposed as phytoremediants, 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.