Study on bioaccumulation and translocation of trace metals by, Eichhornia crassipes and Pistia stratiotes from selected fresh water ecosystems of Goa

Abstract

Aquatic species show different capacities for metal uptake and can accumulate trace metals in roots, stems and/or leaves thereby improving the lake ecosystems. Present study compares the trace metal bioaccumulation and translocation capabilities of two aquatic macrophytes viz. Eichhornia crassipes, and Pistia stratiotes from selected fresh water bodies of Goa. Trace metals from water were extracted using APDC (ammonium pyrorolidene dithio carbamate) and MIBK (methyl isobutyl ketone). Root and shoot samples of selected macrophytes were digested using nitric acid and were aspirated for detection of trace metals using Atomic Absorption Spectrophotometer. Metal concentration in water except Zinc, exceeded the drinking water limits prescribed by WHO. Lotus lake was more contaminated as compared to Curtorim lake as far as trace metal concentration is concerned. Aquatic macrophytes showed absorption of trace metals in the following order for E. crassipes - Fe>Cu>Mn>Zn>Ni>Pb and for P. stratiotes – Cu>Mn>Fe> Zn>Pb>Ni. Absorbed metals were accumulated and translocated in the plant body. Differences in bioaccumulation and translocation factor (BAF and TF) indicate the preferential accumulation/uptake and translocation of metals due to morphological and anatomical peculiarities of selected species. Both aquatic plants have rapid growth rate, high biomass yield, show uptake of a large amount of trace metals, the ability to transport metals in aboveground parts of plants is high, so also the mechanism to tolerate metal toxicity is very high. Environmental factors like pH, solar radiation and nutrient availability greatly influence phytoremediation potential and growth of these plants. BAF and TF were higher than 1 in most of the metals analyzed in case of both the species thus proving to be highly potential for phytoremediation of aquatic bodies contaminated with trace metals.