Biomagnification of Heavy Metals during Vemicomposting of Water Hyacinth by Earthworm

Heavy metals could be bio-concentrated by water hyacinth and might be further cumulated by earthworm via the bio-magnification effect during vemicomposting.In order to realize the biomagnification of heavy metals,the concentrations of Cd(Ⅱ),Cr(Ⅵ),Pb(Ⅱ),Cu(Ⅱ),Ni(Ⅱ) in the leaves and root of water hyacinth cultured in simulated wastewater,earthworms,and wormdung were tested.The results indicated that heavy metals could be bio-concentrated by water hyacinth and the growth rate of earthworms was decreased when the heavy meatals concentrations increased.Nevertheless,most of the heavy metals were distributed in the root.So it was relatively safe to feed earthworms with the leaves.Moreover,earthworms were somewhat patient towards low levels of heavy metals while most of the heavy metals were retained in their dung.