Removal Efficiency, Accumulation and Biochemical Response of Lemna minor L. Exposed to Some Heavy Metals

Abstract

Both terrestrial and aquatic plants can be used for removing various pollutants such as hydrocarbons, heavy metals, etc via phytotechnology. This study applied different concentrations of Cd, Pb, and Cr (1, 4, and 8) mg/L to evaluate heavy metal removal and toxicological effects on Lemna minor L. in laboratory experiments for 12 days. At the beginning and the end of experiments, the parameters were measured, including fresh weight, relative growth rate (RGR), total chlorophyll, protein, and proline content, as well as other parameters measuring at the end of experiments such as metal remaining in water, removal efficiency, and bioconcentration factor(BCF) in plant. The results demonstrated a decrease in metal concentrations in aqueous solution at all treatments with different values. The highest removal efficiencies were Pb >Cr >Cd, respectively. It was 88.8 % at the 1 mg/L of lead and 22.22 % at 8 mg/L of Cd. The toxicological effects on plants as a response to selected metals were increased with increasing concentrations and periods of exposure. The reduction in fresh, dry weight, t. chlorophyll, and protein content were more in Cd>Cr>Pb respectively compared with increased in control treatments. The highest reduction at 8 mg/L of Cd were 0.329 µg/gram, 18.656 % for total chlorophyll and protein content respectively. The result showed the proline content increased with increasing concentration and the value was highest in Cd>Cr>Pb. The results suggest that Lemna minor L. is a good candidate for treating polluted water with heavy metals.