The absorption of metal ions byEichhornia crassipes

Abstract

Uptake of metals by whole Eichhornia crassipes plants and excised roots was studied using a bioassay system. Results indicate that in time-series bioassay at concentration of 10 mg L-1 of either Zn or Cu, rapid uptake by whole plants occurred during the first 4 h, but subsequently levelled off after 48 h. A greater proportion of metals absorbed remain in the root system rather than being translocated to other parts of plant. When treated with different combinations of both Cu and Zn, some synergistic effect of metals appeared to have occurred as indicated by enhanced uptake when bioassays involved combination of metals. Absorption kinetics of monovalent K+ by excised Eichhornia roots after a 24-h treatment, indicated an initial linear trend over the range of 1-10 mg K L-1 , but subsequently levelled off at 15 mg K L-1 concentration with Vmax of 7.5 x 1 o-6 M K g-1 dry tissue h-1 and Km of 1.1 x 1 o-3 M K. Potentiometric titrations revealed existence of pH-dependent charge densities on root system which have variable affinities for cations and helps explain the ability of Eichhornia roots to absorb and accumulate large amounts of metal ions especially at high pH of media.

Water quality improvement through macrophytes—a review

“…Muramoto and Oki (1983) conclude that Eichhornia crassipes is capable in bioaccumulation of heavy metals (Pb, Cr, Cu, Cd, and Zn) from contaminated water. Nor (1990) studied on absorption of heavy metals by Eichhornia crassipes. Tiwari et al (2007) explained that heavy metals Pb, Zn, Mn show greater affinity towards bioaccumulation in their study.…”

“…Presence of higher concentration of heavy metals in plants signifies the biomagnification. Eichhornia crassipes has the unique property to accumulate heavy metals Cd, Cu, Pb and Zn from the root tissues of the plant (Muramoto and Oki 1983;Nor 1990). Pinto et al (1987) demonstrated that the Eichhornia crassipes would also remove silver from industrial wastewater for subsequent recovery with high efficiency in a short time.…”

Comparative assessment of Azolla pinnata and Vallisneria spiralis in Hg removal from G.B. Pant Sagar of Singrauli Industrial region, India

“…The ability of aquatic plants to accumulate toxic metals from water and their physiological impact is well documented (Rai et al 1995;Gupta and Chandra 1996;Sinha et al 1996;Rai 2007b, c;Rai and Tripathi 2007a, b). Many free floating, emergent and submerged species have been identified as potential accumulators of heavy metals (Nasu et al 1984;Sela et al 1989;Nor 1990;Sinha and Chandra 1990;Sinha et al 1993;Rai 2007a). Such plants could be utilized for the amelioration of water quality and for reducing the pollution load in water bodies.…”

Effective utilization of an aquatic weed in an eco-friendly treatment of polluted water bodies

“…Water hyacinth, has the unique property to accumulate heavy metals such as cadmium, copper, lead and zinc in the root tissues of the plant 42 (Muramoto et.al. 1983) and (Nor 1990). In Hong Kong, water hyacinth has been used for freshwater treatment.…”