ACUTE TOXICITY OF A NIGERIAN ARMAMENT FACTORY EFFLUENT ON OREOCHROMIS NILOTICUS (LINNAEUS+)

Abstract

Effluents from a Nigerian armament factory were characterized using standard methods. The acute toxicity of this effluent on Oreochromis niloticus was determined in a 96h static bioassay under laboratory conditions, in 3%, 6%, 9%, 12% and 15% effluent concentrations. The effluent was generally acidic. Fourteen parameters had values above the Federal Environmental Protection Agency (FEPA) limit. The values for ammonia (x=3.0. mg/l), cyanide (x=2.27mg/l), sulphide (x=2.8 mg/l), and total alkalinity (x=403.0 mg/l) were consistently higher than FEPA approved limits in all batches of effluent investigated. Some heavy metals such as Nickel and chromium and also ammonia were consistently high in all the three batches of effluents analysed. The Effluent caused mortality to Oreochromis niloticus. This mortality was dose – dependent and occurred in all effluent concentration used. The 96h LC50 was 4.16% while the lethal time (LT) was 21 hours for the 15% effluent concentration and 84 hours for the 6% effluent concentration. Hyperactivity and disorientation were observed in all fish before death and dead fish was observed to have oedematous gills and copious mucus deposition on the gills and body.