The concentrations of four heavy metals (Pb, Cd, Zn and Cu) in the leaves of two submerged aquatic plants Potamogeton nodosus Poir. and Ceratophyllum demersum L. and the corresponding water and sediment samples were studied in Lake Abha; southwestern Saudi Arabia. Results showed that the concentrations of the four metals in the sediments, especially Cd and Pb were much higher than in the water. Based on the concentrations of the metals in Lake's water and sediment, the four metals are arranged in the following increasing order: Cd>Cu>Pb>Zn. Comparing the two plant species, Potamogeton nodosus showed higher capacity for the accumulation of Pb, Cd, and Zn. The highest concentrations of Pb, Cd, and Zn were found in the leaves of Potamogeton nodosus (26.8, 3.9 and 77.3 µg g-1 DW; respectively), while Cu in the leaves of Ceratophyllum demersum reached 25.5 µg g-1 DW. Significantly positive correlations were observed between the concentrations of Zn, Cu and Cd in the leaves of both aquatic plants and in the water, suggesting the potential use of the two plants for the monitoring of these metals. Results indicated also that the two species have high capabilities to remove heavy metals directly from the contaminated water. The potential use of these plants in wastewater treatment worths further exploration.
Key words: Potamogeton nodosus Poir., Ceratophyllum demersum L., heavy metals, contaminated water, sediment, bioaccumulation.
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