Decontamination of Lead from aquatic environment by exploitation of floating macrophyte Azolla microphylla Kauf

Abstract

Increasing urbanization, industrialization and over population is one of the leading causes of environmental degradation and pollution. Heavy metals viz. Pb, Zn, Cd, As etc. are the toxic pollutants which show hazardous effects on all living beings. Lead is one such pollutant which disrupts the entire food chain and is lethal even at low concentration. The use of aquatic macrophytes, such as Azolla with hyper-accumulating ability is known to be an environmentally friendly option to restore polluted aquatic resources. The limitation of plant growth in the polluted medium can be used as a factor to determine plant tolerance capacity and the adverse toxic effect of these media. In the present work effect of lead toxicity was conducted on Azolla microphylla. Plants were cultured in Hoagland's medium which was supplemented with 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 mg/l of lead. The toxicity symptoms of Pb on A. microphylla showed chlorosis on leaves followed by significant decrease in the relative growth, biomass productivity and total chlorophyll content with increased concentrations. The presence of the ions resulted about 18.34%, 34.90%, 42.84% inhibition of biomass growth in comparison to control condition. With increase in Pb concentration there is decrease in root length noticed in A. microphylla. Increased concentrations of lead in the growth medium enhanced the bio- concentration factor of A. microphylla up to an optimum value of 1395.6 while the relative growth of plants were significantly decreased. It is concluded that A. microphylla is a potential candidate for the removal of Pb from polluted water bodies.