Bio-accumulation and toxicity of lead (Pb) in Lemna gibba L (duckweed).

The vascular aquatic plant Lemna gibba (duckweed) was exposed during seven days to lead (Pb) at concentrations ranging from 50 to 300 mg/L in a greenhouse with controlled photoperiod and temperature. The effects of Pb on growth of Lemna gibba were examined during 13 days in the same experimental design. The maximum accumulation of lead by Lemna gibba occurs during the third day in the 50 mg/L test, and at the sixth day, lead in all test concentrations produces approximately a 100% inhibitory effect on duckweed growth.