Elevated concentrations of heavy metals in water caused by mining activities create significant risks to the environment. Traditional biological methods used to assess heavy metal-related toxicity in aquatic environments are lengthy and labor intensive. Real-time biomonitoring approaches eliminate some of these limitations and provide a more accurate indication of toxicity. This study describes the performance of a flow-through and floating design microbial fuel cell (MFC) biosensors for real-time detection of copper (Cu) and other heavy metal-related toxicity in aquatic environments. Several biomonitoring tests were carried out using Cu and mining effluents as toxicants. The biosensors were able to detect, in real-time, Cu-related toxicity at concentrations as low as 35 - 40 μg L-1, as confirmed by a Daphnia assay. A comparison of the floating biosensor's outputs with Daphnia magna survival rates showed a linear correlation with a coefficient of determination (R2) higher than 0.9. In addition, the flow-through biosensor was shown to be able to detect differences in the quality of two mining effluents with different compositions of heavy metals. Finally, the biosensor's real-time field performance was investigated in two aquatic environments in the Sudbury, Ontario region of Canada.
Keywords: Aquatic toxicity; Biomonitoring; Biosensing; Copper; Daphnia assay; Real time.