Effect of Pyridine and Formaldehyde on a Macrophyte (lemna Minor L.) and a Sludge Worm (tubifex Tubifex Müller) in Fresh Water Microcosms

Pyridine, a suspected genotoxic and formaldehyde, a potent carcinogen, are present in several industrial wastewater including commercial solvent, resin and pesticide manufacturing industries. The extent of pyridine and formaldehyde toxicity in aquatic organisms is unknown. Therefore, in present study the toxicity of pyridine and formaldehyde were investigated in artificial aquatic ecosystem (microcosm) using two freshwater organisms of different trophic levels i.e. a common duckweed; Lemna minor L. and an oligochaete; Tubifex tubifex Müller. In microcosm, formaldehyde was found to be more toxic to chlorophyll (21 days IC50 = 0.08±0.02 mgL-1), protein (21 days IC50 = 0.15±0.02 mgL-1) and biomass (21 days IC50 = 0.18±0.02 mgL-1) contents of L. minor than pyridine. In addition, pyridine was found growth supportive to L. minor at concentration of 0.1-0.3 mgL-1. Formaldehyde was found more toxic than pyridine for T. tubifex. Lethal concentrations for formaldehyde were 0.08±0.004 (LC10–21 days), 0.2±0.03 (LC25–21 days) and 0.39±0.05 mgL-1 (LC50–21 days). For pyridine, lethal concentrations were 0.85±0.08 (LC10-21 days), 2.14±0.2 (LC25-21days) and 4.27±0.3 mgL-1 (LC5021days). The concentration and time dependent decrease in growth rate, soluble protein and glycogen content was observed. To overcome the stress situation, high-energy requirement of worms lead to protein and glycogen catabolism. The results of present study might be an important consideration while assessing the hazards of materials to aquatic organisms or when deriving water quality criteria for aquatic organisms.