Bioaccumulation of Metals by Algae From Acid Mine Drainage: A Case Study of Frongoch Mine (United Kingdom)

Abstract

Acid mine drainage (AMD) contains high concentrations of potentially toxic metals, which contaminates receiving watercourse. In Frongoch Mine (United Kingdom), it is unclear the distribution of metals on indigenous algae and whether these species of algae can accumulate metals. This study investigated the role of indigenous algae for metals removal from AMD and examined if metals can be adsorbed on the surface or/and bioaccumulated in algae. Sequential extraction procedure was applied for algae samples collected from AMD water to identify the forms in which metals are found in algae. Concentrations of Fe, Pb, Zn, Cu, and Cd in algae were determined. AMD samples were found to have pH 3.5 to 6.9 and high concentrations of Zn (351 mg/L) and Pb (4.22 mg/L) that exceeded water quality standards. Algae Ulothrix sp. and Oedogonium sp. were the two main species in the Frongoch AMDs. Concentrations of metals in algae ranged from 0.007 to 51 mg/g and the bioconcentration factor of metals decreased in the following order: Fe>>Pb>>Cu>Cd>Zn. Zn, Cu and Cd were found to be adsorbed on algae surface and bioaccumulated in the algae while Pb and Fe mainly bioaccumulated in the algae. Indigenous algae can be considered as a biogeochemical barrier to bioaccumulate algae and as a bioremediation method. Also, indigenous algae could be used as a bioindicator for the assessment of water pollution at Frongoch Mine and other metal mines.