Pollution des eaux superficielles et des nappes en milieu urbain : cas de la zone industrielle de Douala-Bassa (Cameroun)

Une étude a été menée dans la zone industrielle de Douala-Bassa afin d'évaluer l'ampleur de la pollution des cours d'eau et des nappes superficielles et de prédire la vulnérabilité de ces dernières. L'étude est basée sur l'analyse des eaux issues de deux campagnes de terrain portant chacune sur 7 prélèvements dans les eaux de surface et 8 dans les eaux souterraines. Outre les analyses physico-chimiques de base, la particularité de l'étude a porté sur la caractérisation de la matière organique et la dynamique de métaux lourds, notamment le plomb, lenickel et le cuivre. Les résultats montrent que les eaux de surface sont neutres (pH 6,2), peu minéralisées (conductivité moyenne 262 mS/cm) et peu turbides (7 NTU) à l'amont. Elles s'enrichissent ensuite dans leréseau où elles deviennent acides (pH 5,8), plus minéralisées (623 à 818 mS/cm) suite aux apports générés par les activités industrielles et domestiques. Les eaux de surface sont polluées (carbonique organique total, 13,0 mg/l ; turbidité 168 NTU). Une source potentielle de pollution au nickel et en matière organique est observée dans les eaux souterraines qui compromet l'exploitation durable de cette ressource en eau

An overview of anti-diabetic plants used in Gabon: Pharmacology and Toxicology

© 2017 Elsevier B.V. All rights reserved.Ethnopharmacological relevance: The management of diabetes mellitus management in African communities, especially in Gabon, is not well established as more than 60% of population rely on traditional treatments as primary healthcare. The aim of this review was to collect and present the scientific evidence for the use of medicinal plants that are in currect by Gabonese traditional healers to manage diabetes or hyperglycaemia based here on the pharmacological and toxicological profiles of plants with anti-diabetic activity. There are presented in order to promote their therapeutic value, ensure a safer use by population and provide some bases for further study on high potential plants reviewed. Materials and methods: Ethnobotanical studies were sourced using databases such as Online Wiley library, Pubmed, Google Scholar, PROTA, books and unpublished data including Ph.D. and Master thesis, African and Asian journals. Keywords including ‘Diabetes’ ‘Gabon’ ‘Toxicity’ ‘Constituents’ ‘hyperglycaemia’ were used. Results: A total of 69 plants currently used in Gabon with potential anti-diabetic activity have been identified in the literature, all of which have been used in in vivo or in vitro studies. Most of the plants have been studied in human or animal models for their ability to reduce blood glucose, stimulate insulin secretion or inhibit carbohydrates enzymes. Active substances have been identified in 12 out of 69 plants outlined in this review, these include Allium cepa and Tabernanthe iboga. Only eight plants have their active substances tested for anti-diabetic activity and are suitables for further investigation. Toxicological data is scarce and is dose-related to the functional parameters of major organs such as kidney and liver. Conclusion: An in-depth understanding on the pharmacology and toxicology of Gabonese anti-diabetic plants is lacking yet there is a great scope for new treatments. With further research, the use of Gabonese anti-diabetic plants is important to ensure the safety of the diabetic patients in Gabon.Peer reviewedFinal Accepted Versio

Analysis and field-evaluation of the CERES models'soil components: Nitrogen transfer and transformation

International audienc

Nitrogen-15 tracers combined with tensio-neutronic method to estimate the nitrogen balance of irrigated maize

8 tables 5 graph.International audienc

Transfer of moisture through the unsaturated zone in the tropical forest using the neutron probe

Knowledge of moisture content is crucial in assessing spatial and temporal movement of water through the unsaturated zone. Moisture storage is also important for monitoring the soil water balance and for validation of water balance models. The purpose of this work was to determine and analyse moisture content profiles at point locations in the unsaturated zone of a lateritic soil around Nsimi, south of Cameroon. Neutron probe has been connected to a set of tensiometers in an area of 60 ha. A comparative study between a site covered with vegetation and a site uncovered was conducted to assess the influence of vegetation in the process of moisture transfers. The results showed that the spatial distribution of moisture profiles varied according to the site and the texture of the soil, with in general increasing of moisture from the surface horizon toward the deeper layers. The mean values of moisture varied from θm= 0,397 cm3/cm3 on barren site, against θm= 0,429 cm3/cm3 in vegetation. Values of suction were generally strong in surface and at depth, but weak in the intermediate layers

Rainfall Variability along the Southern Flank of the Bambouto Mountain (West-Cameroon)

This paper presents the rainfall variability along the southern flank of the Bambouto mountain. Data were collected from rain gauges, while spatial variability was estimated through daily recorded data. Monthly and annual data were used to draw isohyetes via the triangular method, with linear interpolations between observation points. Results show that rainfall is highly variable along the slope. Daily rainfall amounts range from 0.1 mm to 120 mm. Mean yearly rainfall is 1918.1 mm. Rainfall amount doesnot have a linear relationship with altitude. Dschang is characterised by abnormally high rainfall. Following a North-South direction, rainfall decreases from Dschang to a Melang-Loung-Djuttitsa axis. From this axis, the gradient reverses as rainfall increases rapidly towards the Mélétan mountain. The existence of the relatively dry zone within the hillside seems to be due to the influence of two air masses. The first is cold and very wet which moves from the Mamfe basin to the summit zone whereit starts to warm up as it flows towards Melang and Loung where temperature increases. The second comes from the south to south-east monsoon which is also impoverished during the ascension to higher altitudes. It is also likely that a third air mass from the dry harmattan is involved depending on the position of the ITCZ.Key words: rainfall, spatial variability, gradient, slope, mountai

Soils and their distribution on Bambouto volcanic mountain, West Cameroon highland, Central Africa

Morphological, physical and chemical studies were carried out on soils of Mount Bambouto, a volcanic mountain of the West Cameroon highland. These studies show that the soils of this region can be divided into seven groups according to Soils Taxonomy USA [Soil taxonomy: a basic system of soil classification for making and interpreting soils surveys: USDA Agriculture Handbook 436: Washington, DC, US Government Pronting Office, 1975, 754]: lithic dystrandept soils, typical dystrandept soils, oxic dystrandept soils, typical haplohumox soils, typical kandiudox soils, tropopsamment soils and umbriaquox soils. A soils map of this region at scale 1:50,000 has been drawn up, using the seven soils groups above as soil cartography units. These soils are organised into of three main categories: soils with andic characteristics in the upper region of the mountain (lithic dystrandept soils, typical dystrandept soils and oxic dystrandept soils); ferrallitic soils in the lower part of the mountain (typical haplohumox soils and typical kandiudox soils) and imperfectly developed soils (tropopsamment soils and umbraquox soils)