ARSENIC BIOACCUMULATION BY MICROALGAE ISOLATED FROM CONTAMINATED SOILS

Soil, sediment and water contamination with arsenic is, nowadays, a huge environmental problem worldwide that can affect the human health. In Brazil there are reports of soil contamination with As in areas close to gold mines, mainly in the Minas Gerais State. Some microalgae have been considered in bioremediation strategies for contaminated soils and water. Such organisms are able to accumulate toxic methals and methalloids. There are reports that some algae can assimilate and metabolize inorganic arsenic converting it into less toxic organic forms through biomethylation. The purpose of this study was to evaluate the potential for bioaccumulation of As by microalgae Chlorella and Ankistrodesmus isolated from contaminated soils. After obtaining unialgal cultures, organisms were transferred to medium containing increasing amounts of arsenic (0, 0.5, 5 and 10 mg L^-1) in three replications. Microalgae were kept under photoautotrophic conditions (22 ± 1ºC, 16/8 h light/dark fotoperiod under fluorescent light at 120 μmols fótons m^-2 s^-1) in a growing chamber. Contents of As bioaccumulated and remaining in the medium were determined by ICP-OES after 0, 48, 120 and 288 h of exposure. Both genera were able to bioaccumulate arsenic from the medium. Bioaccumulation increased as the As contents increased in the medium, reaching close to 13% of the As added to the higher dose. The results suggest potential use of these microalgae in remediation strategies for contaminated areas.