Bioassay analysis of efficacy of phytoremediation in decontamination of coal mine effluent

• Azolla pinnata and Lemna minor significantly alter physicochemical parameters of coal mine effluent.
• Phytoremediation efficacy in detoxification of effluent was analyzed by fish bioassays.
• Tissues metal accumulation reduction was higher in fish exposed to Lemna minor remediated effluent.
• Macromolecules concentration of fish tissues exposed to both the phytoremediated effluents improved significantly.
• The values of condition factor and organosomatic indices of fish exposed to remediated effluents were not equivalent to their values in wild ones.

Phytoremediation efficacy of Lemna minor and Azolla pinnata in decontaminating metals from coal mine effluent (CME) was analyzed using bioassays. Catfish Heteropneustes fossilis were exposed to both the phytoremediated CMEs for the metal bioaccumulation analysis and biochemical alteration in seven vital tissues. Gross concentration of metals accumulated in liver, kidneys, air breathing organs (ABO), skin and muscle were greater in fish exposed to A. pinnata remediated CME (AP-CME) than those exposed to L. minor remediated CME (LP-CME). Total protein concentrations of all the tissues were greater in fish exposed to LP-CME than to AP-CME. Glycogen concentrations were greater in muscle, brain, ABO and skin of LP-CME exposed fish. In remaining tissues (liver, kidneys and gills) concentrations of glycogen were more in AP-CME exposed ones. Total lipid and total DNA concentrations were greater in most of the tissues of fish exposed to LP-CME than to AP-CME. The total RNA concentrations were elevated only in muscle, liver, kidneys and brain of LP-CME exposed fish; in rest of the tissues (gills, ABO and skin) it was greater in AP-CME exposed fish. The values of condition factor (K) and organosomatic index (OSI) of fish exposed to LP-CME and AP-CME were insignificant to those of wild fish. However, the improvements in the biomolecules concentration of tissues of fish exposed to either of the phytoremediated effluent were not equivalent to their concentration in the wild fish. Thus, decontamination of CME by either of these macrophytes was not complete and prolonged exposure of even phytoremediated CMEs exerts deleterious effects on the fish.