Evaluation of Heavy Metal Contamination in Chlorella vulgaris in the Southern City of Iraq Using Scanning Electron Microscopy and the Risk Assessment

Abstract

Heavy metals pose a significant threat to aquatic environments due to their widespread industrial use and untreated disposal into water. Studies have demonstrated that algae can effectively absorb and accumulate heavy metals from polluted areas. The present study investigated the ability of the green alga, Chlorella vulgaris to accumulate some heavy metals. Chlorella vulgaris was isolated and identified from water samples collected from the surface water of the Euphrates River. The alga was treated with different concentrations (10, 15, 20, and, 25 mg/L) of heavy metals (copper, lead, cadmium, and cobalt) for 14 days. Scanning electron microscopy (SEM) was used to examine the surface morphology of algae. The results showed that C. vulgaris can accumulate heavy metals. Cobalt was the highest accumulated metal followed by low accumulated metals of copper, lead, and cadmium. Heavy metal concentrations of cobalt, copper, lead, and cadmium were accumulated in C. vulgaris with concentrations of 0.57, 0.12, 0.05, and 0.02% dry weight, respectively. Cadmium was the most toxic metal to cell shape and contents, followed by cobalt. However, copper and lead showed no effect. The findings of the study suggest that C. vulgaris can be used in bioremediation to remove heavy metal contamination from water.