Cadmium Accumulation by Water Hyacinth and Salvinia Under Different Sulfur Concentrations

Abstract

Cadmium (Cd) accumulation by water hyacinth and salvinia under different sulfur (S) concentrations was studied. Plants were exposed during six days to 0 and 5 µM of Cd in nutrient solution with 0, 400 and 800 µM of S, and then S and Cd contents in tops and roots were determined. Sulfur content was always higher in S-treated plants, independent of the presence of Cd. Cadmium content in Cd-treated plants increased with the addition of S to the nutrient solution in both species. Water hyacinth roots accumulate an average of 1.4 time more Cd than those of salvinia. The increase in S concentration from 400 to 800 µM, however, usually did not result in additional increase in S nor in Cd accumulation. The molar Cd/S ratio after Cd treatment reached average values of about 4.8 in roots and 2.6 in tops in comparison to their respective controls. Both species, therefore, were Cd accumulators and the accumulation was larger in the roots under presence of S. Since water hyacinth produced larger root mass and accumulated more Cd, it showed larger capacity to remove Cd from aquatic systems contaminated with this metal, especially if S is available.