title: Freshwater microcosms-based assessment of eco-toxicological effects of a chemical effluent from the Pilcam industry in Cameroon.
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, macroinvertebrates 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.
authors.affiliation: Laboratory of General Biology, Department of Animal Biology and Physiology, Faculty of Science, University of Yaounde I, Cameroon. monkiedje@yahoo.com
authors.forename: A
authors.initials: A
authors.lastname: Monkiedje
authors.forename: T
authors.initials: T
authors.lastname: Njinel
authors.forename: A L
authors.initials: AL
authors.lastname: Meyabeme Elono
authors.forename: S H
authors.initials: SH
authors.lastname: Zebaze
authors.forename: N
authors.initials: N
authors.lastname: Kemka
authors.forename: P B
authors.initials: PB
authors.lastname: Tchounwou
authors.forename: J E
authors.initials: JE
authors.lastname: Djomo
mesh_terms: D000818:Animals; D044822:Biodiversity; D002163:Cameroon; D023681:Cichlids; D017753:Ecosystem; D056890:Eukaryota / Q000187:drug effects; D005618:Fresh Water / Q000737:chemistry*; D007221:Industry; D007448:Invertebrates / Q000187:drug effects; D010933:Plankton / Q000187:drug effects; D014867:Water / Q000592:standards; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D014877:Water Pollution, Chemical / Q000009:adverse effects*
chemical_list: D014874:Water Pollutants, Chemical; D014867:Water