and reeds (Phragmites) all show potential. Overall, plants like this offer a poten-
tially effective method for the decontamination of effluent, one with negligible
energy input and at low cost.
Experiments with water hyacinth (Eichhornia crassipes) show uptake of up to
Cd, Co, Pb, Hg, Ni and Au from contaminated fresh water, with a total biomass
production of 600 kg Ha–1day–1. Seaweeds can be used to accumulate iodine
from sea water and as indicators of local metal contamination.244 Section N – Human uses of plants