Bioassay analysis of efficacy of phytoremediation technology in decontaminating the toxic effluent released during recovery of metals from polymetallic sea nodules

Efforts have been made to analyse the efficacy of decontamination by phytoremediation technology using fish bioassay method. For this purpose Fish (L. rohita) were exposed to raw effluent, Lemna minor phytoremediated & Azolla pinnata phytoremediated effluent separately for a period of 20 days. Heavy metal analysis, different haematological and biochemical parametres were studied in the blood of raw effluent exposed and phytoremediated effluent exposed fish. Concentration of metals in the blood of the fish exposed to phytoremediated effluents was found to be less than those exposed to raw PMN effluent, perhaps due to decreased concentration of the metals in both the phytoremediated effluents. Different blood profiles like TEC, TLC, Hb, Ht, MCV, MCH, MCHC and differential leukocyte count also improved in phytoremediated effluent exposed fish when compared to raw effluent exposed ones. Concentration of proteins, lipids, glucose, cholesterol & activities of certain enzymes like AST, ALT, ALP, SOD, catalase, lipid peroxidase and lactate dehydrogenase of the blood also showed significant improvement due to phytoremediation of the effluent. Hence exposure to the phytoremediated effluents caused less damage in the fish in comparison to those exposed to raw effluent. However improvement in the health of phytoremediated effluent exposed fish did not reach to the levels of control wild fish.