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Accumulation of Heavy Metals in Maga-Pouss Rice Fields (Far-North Region, Cameroon) and Transfer to Rice Grains

Agricultural Sciences 2024年第3期15卷 311-326页

作者： Diane Madomguia Gilbert Bello Basokdou Kalieu W. Appoline Isabelle Patrice Kuitekam Dongo Edouard Nya serge hubert zebaze togouet Department of Hydraulics and Water Management National Advanced School of Engineering University of Maroua Maroua Cameroon Research Center of Global Studies with Multidisciplinary Units (CREGUM) Maroua Cameroon National Laboratory of Analysis of Agricultural Inputs and Products Ministry of Agriculture and Rural Development Messa-Yaoundé Cameroon Department of Animal Physiology and Biology Faculty of Sciences University of Yaoundé I Yaoundé Cameroon

Monitoring of heavy metals contamination of agricultural products and their transfer and bioaccumulation in crops like rice has become a hot topic worldwide over the last two decades. The present study was carried out to determine the accumulation of heavy metals in rice fields and their transfer to rice grains. Soil, irrigation water and rice grains samples were gathered in Maga-Pouss, Far-North, Cameroon. Concentrations of six heavy metals (lead, cadmium, zinc, copper, iron and mercury) were evaluated by Atomic Absorption Spectrophotometer (AAS). Mercury was not detected in this study. Average concentrations of metals were in this order (in mg/kg): Fe (188.60 ± 97.06) > Pb (63.63 ± 7.11) > Cd (2.59 ± 0.29) > zn (1.10 ± 1.05) > Cu (0.80 ± 0.73) in water and Pb (105.50 ± 31.11) > Fe (105.50 ± 31.11) > Cu (45.93 ± 14.39) > zn (22.52 ± 6.40) > Cd (3.15 ± 0.49) in soil. Water in Maga-Pouss rice fields appears to be more harmful than the soil, notably for lead, cadmium and copper. In rice grains, heavy metals were found in this order (mg/kg): Fe (188.01 ± 82.62) > Cu (27.20 ± 0.00) > zn (23.61 ± 12.42) > Pb (19.50 ± 19.91) > Cd (2.02 ± 1.05). The mean bioconcentration factor (BCF) of metals from soil to rice grains was in the following order: Fe (2.60) > zn (1.05) > Cd (0.64) > Cu (0.59) > Pb (0.18). From water to rice grains, the order is: Cu (37.26) > zn (22.49) > Cd (6.97) > Pb (2.74) > Fe (1.94). Rice field pH and electrical conductivity favored the uptake of lead, copper and cadmium by rice grains. The findings of this study will be good documentation for risk assessment, and decision-making by environmental managers in this region.

关键词： Heavy Metals Rice Field Bioconcenration Factor Maga-Pouss Accumulation

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Spatiotemporal Distribution of Cladocera and Rotifer of the Mangrove Waters of Mouanko(Coastal Cameroon): Influence of Some Abiotic Variables

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Open Journal of Ecology 2022年第10期

作者： dongmo rodrigue nanfack kueppo eric joselly kouedeum gabriel bertrand zambo georges patrick thiery moanono kayo raoul polycarpe tuekam togouet serge hubert zébazé1

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Outcomes of Hemodialysis Patients in Public Centres in Abidjan from September 2018 to October 2021: Data from the Renal Registry of Cote d’Ivoire

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Open Journal of Nephrology 2024年第3期14卷 413-426页

作者： Sery Patrick Diopoh Arthur Kanganga serge Didier Konan Kolo Claude Ouattara Marie-Dominique Kouadio Mohamed Alex Moudachirou Kouamé hubert Yao Department of Medicine and Medical Specialties University Flix Houphout-Boigny Abidjan Cote dIvoire National Centre for Prevention and Treatment of Renal Failure Abidjan Cte dIvoire

Background: Hemodialysis is the most widely used renal replacement therapy in developing countries such as Cote d’Ivoire. Objective: To study the outcome of chronic hemodialysis patients in public centres in Abidjan using data from the Renal Registry of Cote d’Ivoire (2RCI). Method: This was a prospective analytical cohort study of End Stage Kidney Disease (ESKD) patients undergoing iterative hemodialysis in the network of public hemodialysis centres in Abidjan and who had been registered in the 2RCI register by September 2018. Results: Our study involved 363 cases out of 379 patients registered in the 2RCI registry database in 2018. The mean age of the patients was 47.3 ± 12.1 years, with a male predominance (sex ratio 1.97). In 70.24% of cases, they had no health insurance. The average duration of dialysis for our patients was 6.94 ± 4.1 years, with extremes of 2 and 28 years. This duration was less than 5 years in 44.3% of cases, between 6 and 10 years in 42.9% and more than 10 years in 12.6% of cases. The comorbidities found were hypertension in 95.6% of cases, diabetes in 7.8% and HIV in 4.6%. Anemia was found in 68% of cases and stroke in 8.6%. During the study period, 161 deaths were observed, representing a mortality rate of 44.35%. Acute lung oedema (29.8%), stroke (6.8%) and other cardiovascular diseases (19.3%) were the main causes of death. In multivariate analysis, factors such as age ≥ 65 years (HR = 3.66;CI 95% = 1.55 - 8.67;p = 0.003), “married/coupled” status (HR = 2.02;CI 95% = 1.24 - 3.31;p = 0.005) and normal weight at the start of dialysis (OR = 9.59, CI95% = 4.19 - 21.95;p = 0.001) were associated with the risk of death. Conclusion: Hemodialysis is performed in Abidjan on young patients. The mortality rate after three years of dialysis is very high. Hence the need to pursue the policy of decentralizing public centres and optimizing access to dialysis in terms of quality and quantity in order to improve patient survival.

关键词： Chronic Hemodialysis Death Renal Registry Cote d’Ivoire

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Spatiotemporal Distribution of Cladocera and Rotifer of the Mangrove Waters of Mouanko (Coastal Cameroon): Influence of Some Abiotic Variables

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Open Journal of Ecology 2022年第10期12卷 689-710页

作者： Dongmo Rodrigue Nanfack Kueppo Eric Joselly Kouedeum Gabriel Bertrand zambo Georges Patrick Thiery Moanono Kayo Raoul Polycarpe Tuekam togouet serge hubert zébazé Laboratory of Hydrobiology and Environment Faculty of Sciences University of Yaounde I Yaounde Cameroon Department of Biological Sciences Faculty of Sciences University of Bamenda Bamenda Cameroon

The Mouanko mangrove is subjected to major anthropogenic activities such as agriculture, fishing and deforestation, hence information on Cladocerans and Rotifers amongst other aquatic organisms in order to monitor and manage this ecosystem is vital. The aim of this work is to study the physicochemical parameters of the environment that influence the diversity and spatiotemporal distribution of Cladocerans and Rotifers in the mangrove waters of Mouanko. This study was carried out from November 2019 to October 2020 at 8 sampling stations. Both biological and physico-chemical sampling and analyses were done following standard recommendations. The results of the phyico-chemical analyses revealed that the waters of the Mouanko mangroves were slightly basic (7.64 ± 0.71 UC), moderately oxygenated (69.56% ± 14.29%) with low levels of nutrients [ NO -2 (0. 06 ± 0.05 mg/L), NH+4 (0.39 ± 0.3 mg/L) and PO3-4 (up to 0.12 mg/L)] and high values of electrical conductivity (up to 6531.04 μS/cm), salinity (up to 3.71‰). 15 species of Cladocerans and 30 species of Rotifers were identified accounting for a total abundance of 612 ind/L. The species richness was higher in freshwater influenced zones (40 taxa) compared to marinewater influenced zones (17 taxa). Among these species, the Cladocera, Penilia avirostris was the most abundant in marinewater influenced zones (84 ind/L) while the Rotifer, Keratella tecta was the most abundant in freshwater influenced zones (64 ind/L). Shannon-Weaver’s diversity and Pielou’s equitability indices indicated that freshwater influenced zones host a diverse community with a tendency towards equi-partition of species while marinewater influenced zones revealed the opposite. The low levels of organic pollution indicator variables recorded and the high diversity of the freshwater influenced zones population studied attested to the low level of anthropization in this environment. High salinity and electr

关键词： Cladocera Rotifers Spatio-Temporal Distribution Abiotic Variables Coastal Cameroon

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Accumulation of Heavy Metals in Maga-Pouss Rice Fields (Far-North Region, Cameroon) and Transfer to Rice Grains

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Agricultural Sciences（农业科学） 2024年第3期 311页

作者： Diane Madomguia Gilbert Bello Basokdou Kalieu W.Appoline Isabelle Patrice Kuitekam Dongo Edouard Nya serge hubert zebaze togouet

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Self-assembly of colloidal polymers from two-patch silica nanoparticles

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Nano Research 2020年第12期13卷 3371-3376页

作者： Weiya Li Bin Liu Céline hubert Adeline Perro Etienne Duguet serge Ravaine CNRS CRPPUMR 5031Univ.BordeauxPessac33600France CNRS ICMCBUMR 5026Univ.BordeauxPessac33600France CNRS Bordeaux INPISMUMR 5255Univ.BordeauxTalence33400France

We report the formation of colloidal polymers consisting of disk-like silica nanoparticles(NPs)with polystyrene(PS)chains at the bottom of their two cavities assembled through reduction of the solvent quality for the PS chains and linked by hydrophobic *** show that this NPs assembly exhibits a two-stage process involving reaction-controlled polymerization and diffusion-controlled *** polymer networks are produced by the incorporation of three-patch NPs,which serve as branching points between the colloidal *** co-assembling preformed homopolymers composed of patchy NPs of different sizes or surface chemical groups,block copolymers are also *** study provides insight into the process of self-assembly of two-patch NPs by precisely designing the components to generate colloidal analogues of linear macromolecular chains.

关键词： colloidal polymers nanoparticles patchy self-assembly

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Phytoplankton Dynamics of Mokolo and Mopa Ponds in Bertoua City (East-Cameroon)

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Open Journal of Ecology 2020年第7期10卷 482-496页

作者： Janvier Kengne Tenkeu Gwladys Joelle Mogue Kamdem Nectaire Lie Nyamsi Tchatcho Narcisse Mvondo Isabelle Appoline Kalieu Wilfried Takam serge hubert zebaze togouet Laboratory of General Biology Faculty of Science University of Yaounde I Yaounde Cameroon Department of Aquatic Ecosystems Management Institute of Fisheries Science of Yabassi University of Douala Douala Cameroon

This study aims to improve the understanding of algal community’s dynamics in response to different environmental factors in two dam ponds (Mokolo and Mopa) in the city of Bertoua (East-Cameroon). Physicochemical and biological analyzes were carried out monthly by direct sampling at the surface and using Van Dorn bottle at 1 m depth. The organisms were collected using transparent glass vials of about 500 ml and fixed with 2.5 ml of a lugol solution, then analyzed using the Utermôhl method. Physicochemical analyzes show low transparency (75 cm) of the ponds despite their shallow depth (≤150 cm), high levels of dissolved oxygen (>60%), BOD5 (>30 mg/L) and chlorophyll “a” (>30 μg/L). These data made it possible to categorize the Mokolo and Mopa ponds as hypereutrophic with nitrogen as the limiting factor for eutrophication. Biological data show quite diversified ponds with 138 species identified in Mokolo Pond and strongly dominated by Diatoms with 2951 ind. representing 46% of the total abundance. In Mopa Pond, 147 species were identified, mainly represented by Chlorophyceae with 3629 ind. representing 52% of the total abundance. Azpeitia africana

关键词： Bertoua Dynamics Hypereutrophic Phytoplankton Ponds

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Comparing Freshwater Benthic Macroinvertebrate Communities in Forest and Urban Streams of the Coastal Ecological Region of Cameroon

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Open Journal of Ecology 2019年第12期9卷 521-537页

作者： Fils Mamert Onana serge hubert zebaze togouet Antoine Arfao Tamsa Nectaire Lié Nyamsi Tchatcho Siméon Tchakonte Ernest Koji Armel William Yemtsa Yemeli Abigaelle Natacha Sandrine Mouto Makong Department of Aquatic Ecosystems Management Institute of Fisheries and Aquatic Sciences University of Douala Douala Cameroon Department of Animal Biology and Physiology Faculty of Science University of Yaoundé I Yaoundé Cameroon Microbiology and Biotechnology Laboratory Saint Jerome Polytechnic Institute Saint Jerome Catholic University of Douala Douala Cameroon Department of Animal Biology and Physiology Faculty of Sciences University of Douala Douala Cameroon

In this study conducted in the coastal zone of Cameroon, biological indices and functional feeding groups of benthic macroinvertebrates were used to assess the health status of two urban streams. For a better diagnosis, two streams located in coastal forest zone were used as a reference. Benthic macroinvertebrates were sampled monthly over a 3-month period (from May to July 2017) in six urban stations and six forest stations. Measurements of the physicochemical variables were done simultaneously. Physicochemical analysis revealed that urban streams are strongly polluted with high content of decaying organic matters, while forest streams are slightly polluted as indicated by the Principal Component Analysis. Concerning benthic macroinvertebrates, urban streams are poorly diversified with the proliferation of taxa tolerant to water pollution and belonging to the functional feeding groups of collectors-gatherers. Inversely, forest streams are more diversified and dominated by sensitive taxa, most belonging to the functional feeding groups of predators and shredders. These marked differences between biological indices and feeding mode of benthic macroinvertebrates in forest and urban rivers confirm the reliability of benthic macroinvertebrates as good indicators of freshwater ecosystem in the coastal zone of Cameroon.

关键词： Urban and Forest Streams Benthic Macroinvertebrates Water Pollution Biological Indices Functional Feeding Groups

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zooplankton Dynamics of the Kienke Estuary (Kribi, South Region of Cameroon): Importance of Physico-Chemical Parameters

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Open Journal of Ecology 2021年第12期11卷 837-869页

作者： Essomba Biloa Rachel Eliane Noah Ewoti Olive Vivien Tuekam Kayo Raoul Polycarpe Sob Nangou Paul Bertrand Tchakounté Siméon Onana Fils Mamert Nyamsi Tchatcho Nectaire Lié zebaze togouet serge hubert Institute of Fisheries and Aquatic Sciences of Yabassi University of Douala Douala Cameroon Laboratory of Hydrobiology and Environment Faculty of Science University of Yaounde 1 Yaounde Cameroon Laboratory of Microbiology Department of Biological Science Faculty of Science University of Bamenda Bamenda Cameroon

All Cameroonian estuarine systems, like the Kienke estuarine system (urban area of the port city of Kribi), are considered, as everywhere in the world, as unstable and vulnerable coastal ecosystems insofar as they are influenced by anthropogenic activities (port facilities, industrial facilities), without forgetting climate change. The present work was initiated in order to assess the influence of the seasonal evolution of physico-chemical parameters on the dynamics of zooplankton in the estuarine system of the Kienke. A study to assess the influence of seasonal evolution of some physico-chemical parameters on zooplankton population dynamics was conducted from June 2016 to August 2017 in the Kienke estuarine system (Kribi, South Cameroon Region). Samples were collected in five (05) sampling points at the lower stream, at the confluence and then at 100 meters from the bank at sea following a monthly frequency. The Kienke estuary was characterized by spatio-temporal variations of physico-chemical parameters. These parameters are high temperature, relatively high electrical conductivity and salinity, and a relatively basic hydrogen potential (pH). Nutrients (ammonia nitrogen, nitrates and orthophosphates) were relatively low in the Kienke estuary. The organic pollution index (OPI) indicated moderate to high water pollution. At the surface and at depth, during the long dry season (December to February), zooplankton densities were very low in the Kienke estuarine system. But rather high during the main rainy season (August to October). The results show that 105 species of zooplankton belonging to 46 families grouped into four orders were identified. At the surface, 52 species of zooplankton belonging to 23 families and 4 orders were identified, while at depth, 53 species of zooplankton belonging to 23 families were also identified. The most abundant group was the Copepods represented by the following species: Tropocyclops confinis Kiefer, 1930;Mesocyclops

关键词： Dynamics Kienke Estuary Kribi Physico-Chemical zooplankton

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Spatio-Temporal Variation of Dinoflagellates of the Genera Ceratium (Schrank 1793) and Protoperidinium (Bergh 1881) in Relationship with Some Abiotic Variables in the Atlantic Coast of Kribi (South Region—Cameroon)

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Open Journal of Marine Science 2022年第4期12卷 161-184页

作者： François Désiré Owona Edoa Gloria Eneke Takem Pascale Banga Medjo Anselm Crépin Mama Gabriel Bertrand zambo Joselly Éric Kouedeum Kueppo Tahir Safia Mahamat serge hubert zebaze togouet Laboratory of Hydrobiology and Environment Faculty of Science University of Yaoundé 1 Yaoundé Cameroon Hydrological Research Center Institute of Geological and Mining Research of Cameroon Yaoundé Cameroon Ecosystem and Aquatic Resources Laboratory Institute of Fisheries and Aquatic Sciences of Yabassi University of Douala Douala Cameroon

A study to list Dinoflagellates species belonging to the genera Ceratium and Protoperidinium and some abiotic factors associated with them was carried out in the Kribi coast from February 2020 to February 2021 following a monthly sampling frequency. For the inventory, 60 L of water including 20 L on the surface, 20 L in the trophogen layer and 20 L in the tropholytic layer were filtered through a sieve of 20 μm and the retentate obtained was fixed whith lugol for identification and counting operations using an Olympus microscope. The morphotypes of the taxa were filmed using an Omax Toupvix eye camera. Physico-chemical results showed very good water oxygenation (89.35%), low Suspended Solid concentration (6.36 ± 4.71 mg/L), basic pH (8.53 ± 0.4 U.C), average salinity of 15.87 ± 3.1 g/L and conductivity around 26.73 ± 4.96 mS/cm. The average water temperature hovered around 29.51°C ± 1.28°C. The average values of nitrates and orthophosphates showed a progressive enrichment of the waters of the studied section with nitrate (1.52 ± 0.87 mg/L) and orthophosphate (1.84 ± 3.98 mg/L). This work allowed to identify 17 species of the genera Ceratium and 22 of Protoperidinium. The genera Protoperidinium was the most diverse while it was the taxa belonging to the genera Ceratium that had the highest densities. Ceratium furca was the only spatially and seasonally regular species with occurrence frequencies of 75.31% and 79.16% respectively. According to similar studies, 06 species reconized harmful were inventoried during this study. These are Ceratium furca, Ceratium fusus, Ceratium tripos, Protoperidinium divergens, Protoperidinium steinii, Protoperidinium crassipes. Temperature and oxygen are the abiotic factors that showed more affinities with the taxa inventoried in view of the significant correlations obtained. With a view to preventing blooms on the Cameroonian Atlantic coast, regular monitoring of the harmful species identified is desirable.

关键词： Ceratium Protoperidinium Abiotic Factors Atlantic Coast Kribi

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