Influence De L’exploitation Artisanale Du Sable Sur La Santé Et La Sécurité Des Artisans Et L’environnement: Cas De La Carrière De Nkol’Ossananga, Région Du Centre Cameroun

Sand is classified among the low value development minerals, even though it is massively used in the world. The exploitation of that construction mineral at Nkol’Ossananga, around Yaounde, is done by craftsmen in unsafe conditions, such as: the exposure to a wide range of diseases and the destruction of the environment. We carried out a study on occupational health and safety and environmental impacts on the Nkol’ossananga site. Our method consisted firstly of the bibliographic review, sandpit quarry investigations afterwards, and lastly the data analysis. Tabulation of results showed that the population in the site is essentially threatened by diseases such as dysentery (15%), fibromyalgia (25%), typhoid fever (55%), otalgia (10%), ocular pains (15%), and malaria (45%). Craftmen work without any personal protective equipment (PPE) and are often victims of drowning and bacterial infections. The high demand of sand in Yaoundé involves the development of the activity in other sites and, in consequence, there is a deforestation and disappearance of many animals and vegetables species. The soil and water pollution is also noticeable due to pouring of engines waste oil in the site

The Caldera of Mount Bambouto: Volcanological Characterization and Classification

Mount Bambouto culminates at 2744 m (Meletan Mountain) where an elliptical caldera of 16 × 8 km is found. Although that caldera has been a subject of numerous scientific works, complementary studies were needed to bring out additional data used to classify it through the Caldera DataBase of Geyer and Marti (2008). It emerges that Bambouto Caldera codes are 2 and 203 because it is respectively located in Africa and Central Africa according to the numbering system developed in the Catalog of Active Volcanoes of the World. The collapse type of the caldera is piecemeal; this relies on the fact that the caldera floor is uneven. Several rocks crop out in the caldera; accordingly, its code is B, I, T, P, and Ig viz. basalts, intermediate rocks, trachytes, phonolites, and ignimbrites. Bambouto depression is the ignimbrite caldera because it is associated with thick ignimbrite sheer, that ruled its collapse. The chemical analysis of rocks reveals that the magmatic series of Bambouto Caldera is of alkaline type. It has been built through the continental rifting of extensional type (RC-EXT). The collapse process has been followed by post-caldera protrusion of trachytic and phonolitic domes; then, its codes are Type-S and type-MS

Évolution volcanologique du mont Manengouba (Ligne du Cameroun) ; nouvelles données pétrographiques, géochimiques et géochronologiques<br /> Volcanological evolution of the mount Manengouba (Cameroon line), new petrographical, geochemical, and geochronological data

Le mont Manengouba est un complexe volcanique polygénique de la Ligne du Cameroun édifié au Quaternaire, entre 1,55 et 0 Ma, en trois phases principales. La première phase, de 1,55 à 0,7 Ma, correspond à la construction du volcan Elengoum. La deuxième, entre 0,7 et 0,56 Ma, est marquée par l'effondrement de la partie sommitale de l'Elengoum. La troisième, de 0,56 à 0 Ma, voit l'édification du volcan Eboga, puis la formation de la caldeira, et comporte une activité fissurale adventive à partir de 0,48 Ma. Les produits émis définissent une série alcaline sodique, allant des basaltes à néphéline à des trachytes. Toutes ces laves ont évolué par cristallisation fractionnée dans une chambre magmatique périodiquement réalimentée. The mount Manengouba is a polygenic volcanic complex of the Cameroon line, which was built in the Quaternary, between 1.55 and 0 Ma, during three stages. The first stage, from 1.55 to 0.7 Ma, corresponds to the building of the Elengoum volcano. The second, between 0.7 and 0.56 Ma, points to the collapse of the Elengoum summit. The third, from 0.56 to 0 Ma, fits with the erection of the Eboga volcano and its caldera sinking, and, from 0.48 Ma, with the adventive fissural activity. The products define an alkaline sodic series, from nepheline-bearing basalts to trachytes. All the lavas evolved by fractional crystallization in a periodically replenished magmatic chamber

The geodiversity of Lefo and Santa-Mbu Calderas (Bamenda Mountains, Cameroon Volcanic Line): Factor for socioeconomic activities

Lefo and Santa-Mbu calderas are located on the Bamenda Mountains. They are two geological structures that accompanied the construction of the Bamenda Mountains. The geological processes that accompanied their collapse gave them a significant number of geological features. These elements, known as geodiversity components, constitute real assets for ecosystem services in these more or less populated volcanic environments. The present work aims to highlight the ecosystem services of these two calderas in relation to the socio-economic activities they govern. To this end, field and laboratory work was carried out. They revealed that the ecosystem services of the two calderas include: (1) regulation services because the calderas are covered in places by forest reserves, notably that of Bali Ngemba and Bafut Ngemba, and by a grassland with trees that play a crucial role in climate regulation. In addition, these areas are subject to natural hazards such as mass movements and volcanic eruptions; (2) supporting services as they provide a base for human activities, a habitat for wildlife species; (3) provisioning services because the calderas have fairly fertile soils that favour a fairly diversified agricultural activity, making the floor of the Lefo caldera a coffee growing area. These calderas are covered by a herbaceous grassland that favours pastoral activity in the region. In addition, the rocks of these calderas are used in construction, especially in the foundations and walls of houses; (4) cultural services as they provide a setting for traditional ritual practices and plants with therapeutic properties. In addition, it has several geomorphosites whose scientific and additional values favour the implementation of geotourism and offer geological features that are indispensable for the understanding and functioning of the Volcanic Line of Cameroon. These calderas are undeniable assets for the balance of the ecosystem

Petrology, Geochemistry, and Geodynamic Implications of Basaltic Dyke Swarms from the Southern Continental Part of the Cameroon Volcanic Line, Central Africa

Basaltic dyke swarms in the southern continental part of the Cameroon Volcanic Line (Bangangte, Dschang, Manjo areas) are tholeiitic in composition with 46 to 50 wt.% SiO 2 and have moderate Mg-numbers (53–59), medium TiO 2 contents (1.48–2,05 wt.%), and flat to mildly enriched incompatible trace element patterns. Comparison with trace element patterns of representative Cenozoic basaltic rocks of the Cameroon Volcanic Line (Bana anorogenic complex, Mt. Bambouto, Adamawa Plateau basalts) indicates that these dykes are less enriched in light REE and show different incompatible trace element ratios (La/Yb: 5.7 to 8.6; Zr/Nb: 7.6 to 12.0; Ba/Th: 87.7 to 93.3). The trace element patterns of the dykes and their Sr- and Nd- isotope compositions, however, are similar to those of the pre-Cenozoic volcanic rocks of the Benue Trough in Nigeria. Our data therefore suggest that these dykes represent the magmatic history related to the break-up of Africa and South America and are unrelated to the Tertiary volcanism of the Cameroon Line

Resettlement preferences from landslide prone areas in Cameroon: Willingness to move, reasons to stay

© 2019 Information about resettlement preferences is an important prerequisite for the success of voluntary resettlement as a disaster risk reduction strategy. Yet, even in conditions where individual preferences for resettlement are met, resettlement programs may fail. In this study, we confront individual preferences for resettlement with obstacles to resettlement in order to identify conditions for success and failure of voluntary resettlement. Semi-structured interviews and focus groups discussions are combined with a structured household survey and a discrete choice experiment to elicit individual resettlement preferences among farmers living in the landslide-prone Bamboutos caldera, in Cameroon. A mixed logit model and a latent class model are used to assess resettlement preferences and to investigate differences in preferences between socioeconomic groups. We find that, in general, people are willing to resettle away from landslide prone areas to safer areas, but that preferences for resettlement conditions vary between socioeconomic groups. Wealthier households show a greater willingness to resettle, especially to locations with improved road infrastructure, while poorer respondents are less willing to resettle, especially when this can negatively affect their social network. Beyond individual preferences, resettlement strongly depends on group behavior, historical events and trust in institutions. The stumbling blocks in the Bamboutos caldera include border disputes at the resettlement location, the high cost of resettlement and administrative challenges. With this case study, we demonstrate the added value of complementing a discrete choice experiment with qualitative research, as it leads to an integrated view of the resettlement situation of the affected population.status: publishe

Resettlement preferences from landslide prone areas in Cameroon: Willingness to move, reasons to stay

International audienc

Validation d’une méthode de valorisation matière et énergie des huiles de vidange

More than 22,500 tons per year of waste lubricating oil are non-regulatory managed in Cameroon. They are burned in very dangerous conditions when they are not simply dumped in nature. Yet, these wastes are classified as very dangerous for human-beings. The aim of this work is to promote safer methods of disposal of waste lubricating oil in Cameroon by stressing on materials recovery and energetic valorisation in a steam boiler. A combined method of action of melted salt, distillation under low pressure and treatment on activated adsorbed earth (ASFDPRTTA) is efficacious for the task. The oil, treated by this method strips it of polluting chemical in order to obtain a fuel (ecofuel) meeting up the energetic and environmental expectations as required by standards. On the other hand, the fuel presents physicochemical features nearest to the ones of gasoil so that it has been used in a gasoil steam boiler without risk. Also, the fuel served as a base for the regeneration of a new lubricant (envilub) by adding additives in suitably chosen proportions. Our method is using a low cost investment, simple equipment at the point where inexperienced staff with a minimum of training can master it. It also permits job employment opportunities as well as environmental preservation.Au Cameroun, plus de 25 200 tonnes d’huiles de vidange sont gérées annuellement par des méthodes non réglementaires comme par exemple la combustion en foyers non adaptés, voire le rejet direct dans le milieu naturel. Or, ces huiles sont classées parmi les déchets dangereux tant pour l’homme que pour tous les compartiments de l’environnement. Ce travail a pour objectif la valorisation matière et énergie en chaudière de ces huiles par une méthode combinant l’action des sels fondus, distillation sous pression réduite et traitement sur terre absorbante activée (ASFDPRTTA). Il s’agit d’un enchainement de techniques chimiques simples dans des conditions opératoires particulières pour un résultat tout aussi particulier. L’huile usée, traitée par cette méthode, fournit un combustible (écofuel) avec des taux de polluants extrêmement réduits respectant les normes en vigueur. D’autre part, ce combustible présente des caractéristiques physico-chimiques très proches de celles du gazole, permettant son utilisation directe sans restriction dans une chaudière à gazole. Ce combustible a également été utilisé comme base pour la régénération d’un lubrifiant nouveau (envilub) moyennant l’ajout d’additifs dans des proportions convenablement choisies. Notre méthode à moindre coût, utilisant des équipements simples, peut être mise en œuvre par des personnes sans qualification spécifique, associant ainsi la création d’emploi et la préservation de l’environnement

Assessing impacts of sand mining on water quality in Toutsang locality and design of waste water purification system

This paper focuses on assessing and development of water purification system for addressing water quality effects associated with sand mining in Toutsang locality, West-Cameroon. The study approach involved field investigations, laboratory analysis and design of waste water treatment system. Water samples were randomly collected from the study into well-labeled containers and conveyed to Unité de Recherche d’Analyse des Sols et Chimie de l’Environnement, Faculté d’Agronomie et des Sciences Agricoles (FASA) at the University of Dschang for analysis. Results from the physico-chemical analysis show elevated levels of total suspended solids (TSS), magnesium (Mg), turbidity and iron (Fe) in water samples collected downstream of the River close to the mining site, which exceeds the World Health Organization (WHO) standards. Based on the results of the physico-chemical analysis, a waste water treatment comprising of sedimentation tanks is proposed to treat waste water from the sand mining site. The designed water treatment system can be used to treat contaminated water from sand mining sites for domestic use. The proposed model tank needs to be implemented to restore Toutsang Water quality for indoor purpose and household use

The Mount Manengouba, a complex volcano of the Cameroon Line: Volcanic history, petrological and geochemical features

International audienceThe volcanic story of Mount Manengouba is related to four chronological stages: (1) forming of the early Manengouba shield volcano between 1.55 and 0.94 Ma, (2) building of the Eboga strato-cone between 0.94 and 0.89 Ma, (3) caldera collapse and silicic extrusions of the Elengoum Complex between 0.89 and 0.70 Ma, and (4) intra-caldera and flank activity between 0.45 and 0.11 Ma. The volume of the volcano is calculated at 320 km3 ± 5%. The volcanic rocks are attributed to two magmatic outputs. The first and main magma generation produced the shield volcano, the strato-cone, and the syn- to post-caldera extrusions, displaying a complete series from basanites to trachytes (magmatic Group 1). The second magma generation is limited to the late and flank activity evolving from basanites to trachy-phonolite (magmatic Group 2). Both magmatic groups belong to the under-saturated alkaline sodic series. Petrological calculations locate the magmatic reservoir between 37 and 39 km in the upper mantle for the Group 1 lavas, and between 42 and 44 km for the Group 2 lavas. Trachytes were generated in a secondary crustal reservoir. Magmatic series evolve with medium to low pressure fractional crystallization of olivine, pyroxene, oxides, feldspar, and apatite. Significant crustal assimilation is evidenced in trachytes. The magma of Group 1 was generated with 3-6% of partial melting of a moderately enriched source containing 3-7% of garnet. Melting took place in the spinel to garnet transition zone located at 70-90 km and around 25 kb. The magma of Group 2 resulted from a slightly higher partial melting from a less garnet-rich source that indicates uprising of the melting column in the upper part of transition zone. Sr, Nd, and Pb isotope data of the Manengouba rocks and neighboring lavas are analyzed and compared with those of the mafic lavas of the CVL. Three source components are distinguished: a depleted component originated from the asthenospheric swell, a radiogenic component linked to the contaminated lithosphere of the Neoproterozoic mobile belt, and an enriched component or the lithosphere possibly related to pre-rifting magmatic processes