Heavy Metal Pollution in Lentic Ecosystem of Sub-tropical Industrial Region and Its Phytoremediation

摘要

Aquatic pollution pose a serious challenge to the scientific community worldwide, since, lakes/reservoirs find multifarious use and most often their water is used for drinking, bathing, irrigation and aquaculture. In this study, 9 metals and several physico-chemical parameters, collected from 4 sampling sites in a tropical lake receiving the discharge from thermal power plant, coal mine and chlor-alkali industry, during the years from 2004 to 2005, were analyzed. Pertaining to metal pollution, the most polluted site was Belwadah i.e. waters and sediments had the highest concentration of all the relevant metals. The Reference site was characterized by the presence of low concentrations of metals in waters and in sediments. Finally, after completion of the water quality monitoring, two month field phytoremediation experiments were conducted through the design of large enclosures at the discharge point of different polluted sites of the lake. During field phytoremediation experiments using aquatic macrophytes, marked percentage reduction in metals concentrations were recorded. The percentage decrease for different metals was in the range of 25% to 67.90% at Belwadah (with Eichhornia crassipes and Lemna minor), 25% to 77.14% at Dongia nala (with Eichhornia crassipes, Lemna minor and Azolla pinnata) and 25% to 71.42% at Ash pond site of G.B. Pant Sagar (with Lemna minor and Azolla pinnata). Such types of experiments are prerequisite for improved microcosm design and for the systematic extrapolation of information from experimental ecosystems to natural ecosystems.