Evaluating the fate of organic compounds in the Cameroon environment using a level III multimedia fugacity model

A level III fugacity model was developed to evaluate the fate of chemicals in the Cameroon environment. The model required as input physical-chemical properties, mode and amount of chemical released and environmental characteristics. These were used to predict the distribution of the chemical in the environment, quantify intermedia transfer processes and the major loss mechanisms from the environmental compartments. Five pesticides (endosulfan, chloropyrifos, cypermethrin, deltamethrin and -cyhalothrin) representing volatile, water soluble and persistent compounds were selected for model evaluation. Furthermore, a sensitivity analysis was performed to identify the key input parameters. Model simulations indicated significant differences in the fate of the chemicals that could be explained by the variation in physical-chemical properties. The log KOW, emission rate to water (EW), volume of the water compartment (VW) and the half-life in water and sediment were identified the as the key parameters influencing the predicted water concentrations. The model developed introduces a cost effective and simple method for screening and identifying priority chemicals. It could also be used to perform baseline exposure and risk assessment of chemicals used in Cameroon where very little data is available for exposure to chemicals due to the huge costs associated with setting up a monitoring program

Nitrate and ammonium levels of some water bodies and their interaction with some selected properties of soils in Douala metropolis, Cameroon

The present study examined the nitrate (NO3-) and ammonium (NH4+) levels of Rivers Wouri and Dibamba and some streams that feed them. The interaction of NO3- and NH4+ with some soil properties was also investigated. It was necessitated by the usage of these rivers for livelihood, despite the deposition of discharges into these streams. Twenty eight (28) surface water and four soil samples were collected from various sites within the Douala metropolis. The water was analysed for pH, electrical conductivity (EC), NO3-, NH4+ while the soil was analysed for particle size and cation exchange capacity (CEC). In both cases, standard methods were used. The NO3- and NH4+ levels were higher than the WHO threshold levels in some sites. Nitrate and NH4+ levels of 341.6 and 632.8 mg/l, respectively, were observed in some sites in Dibamba River despite the high level of clay in this area. The values in the Wouri River were low, contrary to the low level of clay in this area. This trend was also reflected in the streams that feed both rivers. The NH4+/NO3- molar ratio was low in areas proxy to the industries reflecting industrial source of  pollution. The continuous use of water from Rivers Wouri and Dibamba for domestic purposes is variably unsafe and needs attention.Key words: Nitrate, ammonium, water bodies/quality, soils, Douala metropolis

Contribution of some water bodies and the role of soils in the physicochemical enrichment of the Douala-Edea mangrove ecosystem

The effect of enrichment of water bodies could be of serious crises to the mangrove ecosystem. Changes in physicochemical properties of some water bodies in the Douala-Edea mangrove ecosystem was investigated alongside the potential role of soils in controlling these parameters. Water and soil samples within the Douala industrial zones were collected in February 2010 and analysed using standard methods. The concentrations of cations and chlorides (Cl-) in the rivers increased from upstream to downstream and with depth. These parameters were not distinct with other anions which showed higher fluctuations around confluences. Many anomalies were obtained in streams and wells at vicinity of the industries. Mean Cl- concentrations in streams and wells around River Wouri (135.1 and 57.9 mg/l, respectively) were higher than those around River Dibamba (59.3 and 38,2 mg/l, respectively). A low retention capacity of the soils was observed by the non significant (P > 0.05) relationship between the clay fraction and cation exchange capacity (CEC). This makes the mangrove  ecosystem vulnerable to the increase nutrient from anthropogenic activities as indicated by the occurrence of Nypa Palms (Nypa fructicans) and Water Hyacinths (Echhornia cassipes). It is therefore imminent that the Douala-Edea Mangrove Ecosystem is being degraded.Key words: Soils, water, physicochemical properties, mangrove ecosystem

Utopias, Transgressions and Hybridity: Amadou Secks's Representation of Postcoloniality in Saaraba

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Chinua Achebe: Things Fall Apart

This lecture on Chinua Achebe\u27s Things Fall Apart, delivered at Lawrence University on March 4, 2002, was designed for students and faculty in the college\u27s Freshman Studies program. Freshman Studies, a multidisciplinary introduction to the liberal arts, has been the cornerstone of the Lawrence curriculum for over fifty years. The lecturer, Lifongo Vetinde, is an assistant professor of French at Lawrence. Vetinde holds the M.A. and the Ph.D. from the University of Oregon. He has presented papers and led panels at conferences of the Modern Language Association and has published numerous book reviews

Chinua Achebe: Things Fall Apart

This lecture on Chinua Achebe\u27s Things Fall Apart, delivered at Lawrence University on March 5, 2001, was designed for students and faculty in the college\u27s Freshman Studies program. Freshman Studies, a multidisciplinary introduction to the liberal arts, has been the cornerstone of the Lawrence curriculum for over fifty years. The lecturer, Lifongo Vetinde, is an assistant professor of French at Lawrence. Vetinde holds the M.A. and the Ph.D. from the University of Oregon. He has presented papers and led panels at conferences of the Modern Language Association and has published numerous book reviews