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Freshwater Microcosms-Based Assessment of Eco-toxicological Effects of a Chemical Effluent from the Pilcam Industry in Cameroon
Laboratory of General Biology, Department of Animal Biology and Physiology, Faculty of Science, University of Yaounde I, P.O. Box 812, Cameroon
Molecular Toxicology Research Laboratory, NIH-Center for Environmental Health, College of Science, Engineering and Technology, Jackson State University, 1400 Lynch Street, P.O. Box 18540, Jackson, Mississippi, USA
Laboratory of Animal Biology, University of Dschang, Cameroon
* Author to whom correspondence should be addressed.
Received: 28 January 2004; in revised form: / Accepted: 16 June 2004 / Published: 30 September 2004
Abstract: We studied the acute toxicity of a raw effluent from a battery manufacturing plant (Pilcam) in Douala, Cameroon, to a freshwater fish (Oreochromis niloticus), and subsequently evaluated its sub-acute effects on water quality and the biota in freshwater microscosms. The acute toxicity test was based on 96 hrs static renewal bioassays that resulted in 96-h LC50 and LC90 values of 16 and 20.7% (v/v), respectively. The sub-acute experiments were conducted by exposing several species of aquatic organisms (plankton, macro-invertebrates and mollusks) to lower effluent concentrations [1.6%, 8.0%, 16% (v/v)] for six weeks, and monitoring their survival rates, as well as the physical and chemical characteristics of water. These concentrations were based on 10%, 50%, and 100% of the 96 h - median lethal concentrations (LC50) of the effluent to the freshwater fish, Oreochromis niloticus. Significant effects on functional parameters, such as, chlorophyll-a and total protein could not be demonstrated. However, the activity of alkaline phosphatase was significantly inhibited at all concentrations tested. Phytoplankton, zooplankton, macro-invertebrate communities and snails were negatively affected by the effluent application at concentrations ≥ 8% (v/v), with chlorophyta, ciliates, ostracoda, annelida, planaria and snails being the most sensitive groups. The snails were eliminated after 24 h exposure from microcosms treated with effluent at concentration ≥ 8% (v/v). Effluent exposure also caused significant effects on water quality parameters (DO, pH, hardness, conductivity, color, turbidity, ammonia) in general at concentrations ≥ 8% (v/v). Temperature and alkalinity were not significantly affected. Overall, data from this research indicate that a dilution of the Pilcam effluent down to 1.6% does not provide protection against chronic toxicity to aquatic organisms. Further studies are needed to determine the no observable adverse effect level (NOAEL), as well as a chronic reference concentration for this effluent.
Keywords: Industrial chemical effluent; aquatic microcosm; ecotoxicological effects; water quality
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Monkiedje, A.; Njine, T.; Meyabeme Elono, A.L.; Zebaze, S.H.; Kemka, N.; Tchounwou, P.B.; Djomo, J.E. Freshwater Microcosms-Based Assessment of Eco-toxicological Effects of a Chemical Effluent from the Pilcam Industry in Cameroon. Int. J. Environ. Res. Public Health 2004, 1, 111-123.
Monkiedje A, Njine T, Meyabeme Elono AL, Zebaze SH, Kemka N, Tchounwou PB, Djomo JE. Freshwater Microcosms-Based Assessment of Eco-toxicological Effects of a Chemical Effluent from the Pilcam Industry in Cameroon. International Journal of Environmental Research and Public Health. 2004; 1(2):111-123.
Monkiedje, A .; Njine, T.; Meyabeme Elono, A. L.; Zebaze, S. H.; Kemka, N.; Tchounwou, P. B.; Djomo, J. E. 2004. "Freshwater Microcosms-Based Assessment of Eco-toxicological Effects of a Chemical Effluent from the Pilcam Industry in Cameroon." Int. J. Environ. Res. Public Health 1, no. 2: 111-123.