Transition Metals in Decomposing Macrophytes in a Wetland System

Abstract

The present work provides the baseline information on concentrations of select transition metals (iron, manganese, copper, zinc, nickel, lead and chromium) in seven macrophytes and their changes in the course of their decomposition in the wetlands of Keoladeo National Park, Bharatpur, India. Litterbag experiments were carried out in nylon litterbags of two different mesh sizes (0.14 and 0.375 mm) in the field and in the laboratory water tanks. The macrophytes selected for the study were Paspalum distichum, Paspalidium punctatum, Cyperus alopecuroides, Pseudoraphis spinescens, Ipomoea aquatica, Neptunia olearhiza and Hydrilla verticillata, which dominate the aquatic vegetation of the wetland system. On the whole there was no notable influence of mesh size on the release of metals from the decomposing plant matter. In field condition the level of Cr, Ni and Pb in plant matter at the end increased while their levels decreased in water indicating the uptake and accumulation of metals in plants from the surrounding water column during decomposition.