Assessment of algae as mercury bioindicators in acid mine drainage waters and their potential for phytoremediation
Date
2014-07-22
Authors
Tshumah-Mutingwende, Rosamond Rosalie Marigold Setswa
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Abstract
The use of algae as heavy metal bioindicators in aquatic environments has
received much attention. In this study, the performance of a common freshwater
living green alga, Cladophora sp. as a mercury bioindicator and its potential for
phytoremediation applications was assessed by various parameters which included
the influence of contact time, pH, initial mercury concentration and the presence
of competing metal cations. A rapid uptake of mercury by Cladophora sp. was
displayed. More than 99% of mercury in solution was removed within the first 5
min of contact and equilibrium was attained after 10 min. High adsorption
capacities of 800 mg kg-1, 530 mg kg-1 and 590 mg kg-1 at pH 3, 6.5 and 8.5
respectively were obtained at the optimum mercury concentration of 1.0 mg l-1.
Competitive adsorption studies showed that the selectivity of heavy metal cations
by Cladophora sp. was in the following order: Hg2+ ˃Fe2+˃Cu2+˃ Zn2+ ˃ Co2+.
These results indicate that living Cladophora sp. algae are suitable for use as
mercury bioindicators in AMD waters and are also suitable for the removal of
mercury in AMD conditions.