Responses of green algae and diatom upon exposure to chromium and cadmium

In this study, the detrimental effects of trace metals on the growth of phytoplankton and the phytoremediation potential of microalgae from Vietnam are elucidated. Two green algae Scenedesmus accuminatus var biseratus and Scenedesmus protuberans, along with the diatom species Cyclotella sp., were exposed to chromium (Cr) and cadmium (Cd) at three distinct concentrations ranging from 5-761 µgl-1 and 18-667 µgl-1, respectively, over a period of 14 days. The results indicated that S. acuminatus var biseratus and Cyclotella sp. were relatively tolerant to Cr, even at the highest test concentration, while the growth rate of S. protuberans was significantly inhibited when exposed to 660 µgl-1 of Cr. Only Cyclotella sp. showed a high Cd tolerance, whereas Cd at concentrations of 493 and 607 µgl-1 prohibited the growth rate of S. acuminatus and S. protuberans, respectively. Moreover, at the concentrations tested, all three algal species could remove 90-100% of the Cr out of the test medium. The diatom Cyclotella sp. could reduce up to 99% of Cd whereas the two green algae could only do not remove more than 13% of Cd from the test medium. We strongly recommend the Cyclotella sp. as a candidate for phytoremediation in metal-contaminated water. Our results contribute vital information toward solutions that environmental experts and managers are searching for to resolve pollution caused by trace metal contaminants.