Asian Journal of Microbiology, Biotechnology & Environmental Sciences Paper

BIOMONITORING OF TRACE ELEMENTS IN SOME SELECTED AQUATIC MACROPHYTES WITH REFERENCE TO LAKE CONTAMINATION: A CASE STUDY OF PARIYEJ COMMUNITY RESERVE, GUJARAT, INDIA

J. I. NIRMAL KUMAR, HIREN SONI, RITA N. KUMAR AND IRA BHATT

Abstract

A biomonitoring study was carried out at Pariyej reservoir, an internationally important wetland listed in Asian Directory of Wetlands, designated as a "Wetland of National Importance" and a proposed community reserve of Gujarat State, India, to ascertain the degree of trace element contamination. The study focused on assessment of trace element contamination in certain aquatic macrophytes used as biomonitors, in comparison with water and sediments (abiotic monitor) for heavy metal pollution. Good information was provided by analyzing the roots, stems and leaves of native aquatic plants (biomonitors) represented by seven species: Eichhornia crassipes, (Mart.) Solms, Echinochloa colonum (L.) Link, Hydrilla verticillata (L.f.) Royle, Ipoinoea aqua tica Forsk., Nelumbo nucifera Gaert.h., Typha angustata Bory & Chaub and Vallisneria spiralis L. alongwith surface sediments and water, were analyzed for Cd, Co, Cu, Ni, Pb and Zn contamination. The highest concentration of the trace elements was measured in Nelumbo nucifera and the lowest in Echinochloa colon um. Based on the concentration and toxicity status observed in the lake's vegetation, the six metals are arranged in the following decreasing order: Zn > Cu > Pb >Ni > Co > Cd. Compared with the standard, normal and critical toxicity range in plants, the detected values of Cd and Ph falls within normal range, while that of Co and Ni was within the critical range. However, Zn and Cu showed the highest concentration with alarming toxicity levels, which are considered as one of the most hazardous pollutants in Pariyej reservoir. Certain species of aquatic macrophytes are also proposed as biomonitors (and/or biofilters/absorbers) such as Typha angustata and Ipomoea aquatica, which are the two most useful plant species in biomonitoring studies due to their ability to accumulate elements in high concentration in the roots. The results showed the significant difference in accumulation of metals like Zn, Cu and Pb in different plant organs, which showed more accumulation in roots than that of stems and leaves. High positive correlation between combinations of different metal pairs in plant's root, stern or leaf system was established.