Dunaliella salina as marine microalga highly tolerant to but a poor remover of cadmium

Cadmium tolerance and removal in the marine microalga Dunaliella salina were studied in cultures exposed to different metal concentrations (5-120 mg Cd l−1) for 96 h. This microalga can be included in the group of microalgal species most tolerant to cadmium due to the high value of EC50 that it possesses (48.9 mg Cd l−1 at 96 h of culture). The greater percentage of cadmium removed was obtained in cultures exposed to 5 mg Cd l−1 at 96 h, but removing only 11.3% of the added cadmium. In all cultures, the quantity of cadmium removed intracellularly was much lower than the bioadsorbed quantity and it was proportional to the sulfhydryl group levels. Both the Freundlich and Langmuir adsorption models were suitable for describing the short-term biosorption of cadmium by living cells of D. salina.