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This study assessed the mineralogical and geochemical characteristics of geophagic clays sold in some markets in Cameroon to ascertain their provenance, contamination status and human health risk. To achieve this, 40 samples from 13 markets in Cameroon were purchased and analysed using X-ray diffractometry, X-ray fluorescence and laser ablation inductively coupled plasma mass spectrometry for their mineralogy and geochemistry, respectively. The geophagic clays were dominantly made up of kaolinite and quartz. Their chemistry was dominated by SiO2, Al2O3 and LOI with means of 48.76 wt%, 32.12 wt% and 13.93 wt%, respectively. The major, trace and rare earth elements data showed that these geophagic clays were predominantly derived from felsic rocks. The contamination assessment indicated no enrichment of metals from anthropogenic sources, except for Zn in samples from Acacia, Madagascar and Mfoudi markets. The index of geo-accumulation indicated no contamination to moderate contamination of the clays. The non-carcinogenic index values for Fe, Co, Cr, Cu, Ni, Pb and Zn were generally less than 1, suggesting no non-carcinogenic risk exposure to children and adults consuming the geophagic clays from these metals. The carcinogenic risk index (TCR) for Ni and Cr were above 10−6, which implies that children and adults are vulnerable to minimal carcinogenic health risk. The TCR values from Ni posed the highest risk, especially to children consuming clays from some markets.
Georges-Ivo Ekosse; George Nkeng; Nenita Bukalo; Olaonipekun Oyebanjo. Geophagic Clays from Cameroon: Provenance, Metal Contamination and Health Risk Assessment. International Journal of Environmental Research and Public Health 2021, 18, 8315 .
AMA StyleGeorges-Ivo Ekosse, George Nkeng, Nenita Bukalo, Olaonipekun Oyebanjo. Geophagic Clays from Cameroon: Provenance, Metal Contamination and Health Risk Assessment. International Journal of Environmental Research and Public Health. 2021; 18 (16):8315.
Chicago/Turabian StyleGeorges-Ivo Ekosse; George Nkeng; Nenita Bukalo; Olaonipekun Oyebanjo. 2021. "Geophagic Clays from Cameroon: Provenance, Metal Contamination and Health Risk Assessment." International Journal of Environmental Research and Public Health 18, no. 16: 8315.
Eight kaolinitic materials from the Lokoundje River at Kribi were sampled and investigated for their physical, chemical, mineralogical and thermal characteristics in order to evaluate their potential suitability as raw materials in ceramics. The Lokoundje kaolinitic materials are clayey to silty clayey and are predominantly composed of kaolinite and quartz. The alkali (Na2O + K2O) content ranges between 1 and 2.5 wt.%; these low values do not favor vitrification of the ceramics but may be improved through flux amendment. The presence of goethite in some samples limits their utilization in white ceramics. The minerals content, color, metallic sound, cohesion, linear shrinkage, flexural strength, bulk density, water absorption and microstructure were determined. The XRD data reveal that kaolinite and goethite were transformed, respectively, into mullite and hematite. The colors of the fired products are characteristic of their mineral assemblage. The metallic sound is indicative of low vitrification which is confirmed by the presence of cracks due to low flux contents. The cohesion is good to very good, due to the abundance of kaolinite. The physicomechanical properties increase with temperature as well as densification. The geochemical data show that the Lokoundje alluvial clays are suitable for the manufacture of white stoneware tiles.
Paul-Désiré Ndjigui; Jean Mbey; Soureiyatou Fadil-Djenabou; Vincent Onana; Elie Bayiga; Christophe Enock Embom; Georges-Ivo Ekosse. Characteristics of Kaolinitic Raw Materials from the Lokoundje River (Kribi, Cameroon) for Ceramic Applications. Applied Sciences 2021, 11, 6118 .
AMA StylePaul-Désiré Ndjigui, Jean Mbey, Soureiyatou Fadil-Djenabou, Vincent Onana, Elie Bayiga, Christophe Enock Embom, Georges-Ivo Ekosse. Characteristics of Kaolinitic Raw Materials from the Lokoundje River (Kribi, Cameroon) for Ceramic Applications. Applied Sciences. 2021; 11 (13):6118.
Chicago/Turabian StylePaul-Désiré Ndjigui; Jean Mbey; Soureiyatou Fadil-Djenabou; Vincent Onana; Elie Bayiga; Christophe Enock Embom; Georges-Ivo Ekosse. 2021. "Characteristics of Kaolinitic Raw Materials from the Lokoundje River (Kribi, Cameroon) for Ceramic Applications." Applied Sciences 11, no. 13: 6118.
The demand for kaolinitic clays for various industrial applications is increasing globally. The present study evaluated the potential industrial applications of kaolins from the Eastern Dahomey and Niger Delta Basins, Nigeria. The colour, pH, electrical conductivity (EC), particle size distribution (PSD), plastic limits and liquid limits of the kaolins were determined. Mineralogical properties were assessed using X-ray diffractometry (XRD), scanning electron microscopy (SEM), and differential thermal analysis (DTA). The chemical compositions of the kaolins were determined using X-ray fluorescence spectrometry (XRF). The kaolins were generally acidic, with pH less than 7 with low EC. The moderate plasticity indices (PI ≥ 10%) for the kaolins suggested their potential use in the manufacturing of structural clay products without extrusion. Kaolinite was the only kaolin mineral present with anhedral–subhedral–euhedral crystals. The platy morphology of the kaolinites in the Cretaceous kaolins are very important in paper production. Other minerals present in the kaolins were quartz, muscovite, anatase and goethite. The major oxide contents of the kaolins were dominated by SiO2, Al2O3, Fe2O3 and TiO2. Based on chemical specifications, the raw kaolins are not suitable for most industrial applications except for the Cretaceous Lakiri kaolins in the paper and ceramic industries (except for TiO2 and K2O content). The study concluded that the kaolin deposits would require beneficiation for large-scale industrial applications.
Olaonipekun Oyebanjo; Georges-Ivo Ekosse; John Odiyo. Physico-Chemical, Mineralogical, and Chemical Characterisation of Cretaceous–Paleogene/Neogene Kaolins within Eastern Dahomey and Niger Delta Basins from Nigeria: Possible Industrial Applications. Minerals 2020, 10, 670 .
AMA StyleOlaonipekun Oyebanjo, Georges-Ivo Ekosse, John Odiyo. Physico-Chemical, Mineralogical, and Chemical Characterisation of Cretaceous–Paleogene/Neogene Kaolins within Eastern Dahomey and Niger Delta Basins from Nigeria: Possible Industrial Applications. Minerals. 2020; 10 (8):670.
Chicago/Turabian StyleOlaonipekun Oyebanjo; Georges-Ivo Ekosse; John Odiyo. 2020. "Physico-Chemical, Mineralogical, and Chemical Characterisation of Cretaceous–Paleogene/Neogene Kaolins within Eastern Dahomey and Niger Delta Basins from Nigeria: Possible Industrial Applications." Minerals 10, no. 8: 670.
The deliberate consumption of earthly materials is a universally recognised habit with health benefits and risks to those that practice it. Thirteen (13) samples comprising of six (6) Cretaceous and seven (7) Paleogene/Neogene geophagic kaolinitic materials, respectively, were collected and analysed for trace element concentrations (V, Cr, Co, Ni, Zn, Pb, and Fe), and possible risk on consumers’ health. The trace element compositions were obtained using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) and X-ray fluorescence spectrometry (XRF) analytical methods. Based on their average concentrations, Fe > V > Cr > Ni > Zn > Pb > Cu > Co and Fe > V > Cr > Zn > Cu > Pb > Ni > Co for the Cretaceous and Paleogene/Neogene geophagic clays, respectively. Iron concentrations were significantly higher in Paleogene/Neogene geophagic clays than in Cretaceous geophagic clays. The nutritional value of Cu and Zn were lower whereas, Cr and Fe were higher than the recommended dietary intake. The index of geoaccumulation (0 < Igeo ≤ 1) showed that the geophagic materials were uncontaminated to moderately contaminated by the trace elements. The overall hazard indices (HI) for non-carcinogenic effects showed that the geophagic clays pose threat to children (HI > 1) and no threat to adults (HI < 1) health. However, the carcinogenic risk indices (CRI) for Cr, Ni, and Pb were within acceptable cancer risks (10−6 < CRI < 10−4) for children and adults. Hence, based on the trace element s HI and CRI, this study concluded that the consumption of Cretaceous and Paleogene/Neogene geophagic kaolinitic clays poses no risks to adult health but children might suffer health risk if the geophagic clays are not beneficiated before ingestion.
Olaonipekun Oyebanjo; Georges-Ivo Ekosse; John Odiyo. Health Risk Evaluation of Trace Elements in Geophagic Kaolinitic Clays within Eastern Dahomey and Niger Delta Basins, Nigeria. International Journal of Environmental Research and Public Health 2020, 17, 4813 .
AMA StyleOlaonipekun Oyebanjo, Georges-Ivo Ekosse, John Odiyo. Health Risk Evaluation of Trace Elements in Geophagic Kaolinitic Clays within Eastern Dahomey and Niger Delta Basins, Nigeria. International Journal of Environmental Research and Public Health. 2020; 17 (13):4813.
Chicago/Turabian StyleOlaonipekun Oyebanjo; Georges-Ivo Ekosse; John Odiyo. 2020. "Health Risk Evaluation of Trace Elements in Geophagic Kaolinitic Clays within Eastern Dahomey and Niger Delta Basins, Nigeria." International Journal of Environmental Research and Public Health 17, no. 13: 4813.
Geothermal springs are natural geological phenomena that occur throughout the world. South Africa is blessed with several springs of this nature. Limpopo province contains 31% of all geothermal springs in the country. The springs are classified according to the residing mountain: Soutpansberg, Waterberg and Drakensberg. This study focused on the geothermal springs within the Soutpansberg region; that is, Mphephu, Siloam, Sagole and Tshipise. The study was aimed at assessing the occurrence and potential health risk associated with drinking water from geothermal springs within Soutpansberg. Geothermal springs and boreholes were sampled for a period of 12 months (May 2017–May 2018) to accommodate two major seasons in the study areas. The physicochemical and trace metal compositions of the geothermal springs and boreholes (tepid and hot) were analyzed using ion chromatography (IC) (Dionex Model DX 500) and inductively coupled plasma-mass spectrometer (ICP-MS). Trace metal concentrations of the geothermal springs and boreholes were within permissible drinking water guidelines by the South African National Standards (SANS) and World Health Organisation (WHO), with exception of mercury (Hg), which is high in summer season. The bioaccumulation from regular consumption could, however, result in negative effects. Pearson’s correlation revealed that there is a direct relationship between temperature and pH, and some of the trace metals (V, Zn, Hg, Pb). This implies dissolution of minerals (rock-water interaction) under slightly high temperature. Multivariate statistics further elucidate the relationship and possible sources of the trace metals. Therefore, it can be inferred that the rock-water interaction is the main geochemical process governing the release of trace metals in groundwater. Hazard Index values for both children and adults were higher than 1, and this implies that the communities are at high risk of non-cancer health effects. Further, As, Cr and Cd were found to be the highest contributors to the potential cancer risk in the study areas, with children having a higher risk than adults. Therefore, there is a need for clinical/epidemiological study, and regular monitoring and control measures, to verify actual prevalence of cancer and protect human health, particularly the children, within the study areas.
Olatunde Samod Durowoju; Georges-Ivo Ekosse Ekosse; John Ogony Odiyo. Occurrence and Health-Risk Assessment of Trace Metals in Geothermal Springs within Soutpansberg, Limpopo Province, South Africa. International Journal of Environmental Research and Public Health 2020, 17, 4438 .
AMA StyleOlatunde Samod Durowoju, Georges-Ivo Ekosse Ekosse, John Ogony Odiyo. Occurrence and Health-Risk Assessment of Trace Metals in Geothermal Springs within Soutpansberg, Limpopo Province, South Africa. International Journal of Environmental Research and Public Health. 2020; 17 (12):4438.
Chicago/Turabian StyleOlatunde Samod Durowoju; Georges-Ivo Ekosse Ekosse; John Ogony Odiyo. 2020. "Occurrence and Health-Risk Assessment of Trace Metals in Geothermal Springs within Soutpansberg, Limpopo Province, South Africa." International Journal of Environmental Research and Public Health 17, no. 12: 4438.
Hydrogen (D) and oxygen (18O) isotopic compositions of precipitation are useful tools to delineate the nature of precipitation, groundwater recharge and climatological investigations. This study investigated the isotopic composition of 12 rainfall occurrences at Thohoyandou, with the objective of generating the local meteoric water line (LMWL) and determining the factors controlling the isotopic composition of the rain. The delta (δ) values for D and 18O of the samples were determined using a Thermo Delta V mass spectrometer connected to a Gasbench. Thohoyandou rainwater showed a wide range of stable isotope values; δD values of the rainwater varied from −76.3‰ to +22.7‰ (SMOW) with a weighted mean of −9.8‰ and δ18O values ranged from −10.78‰ to +3.07‰ (SMOW) with a weighted mean of −2.7‰. δ-values of rainwater were more enriched during winter and more depleted during summer, due to the amount of rainfall and seasonal effect. The LMWL in Thohoyandou is defined by δD = 7.56δ18O + 10.64, which shows a similar slope to the global meteoric water line (GMWL) but with a slightly higher intercept, of 10.64‰ instead of 10‰. This implies that the process of rain formation in Thohoyandou occurred under equilibrium conditions which are not significantly affected by evaporation. The slightly higher d-intercept value above the GMWL reflects an additional supply of recycled moisture across the regions. This implies that there is no continental effect but inland moisture from various water bodies and vegetation.
Olatunde Durowoju; John Ogony Odiyo; Georges-Ivo Ekosse. Determination of isotopic composition of rainwater to generate local meteoric water line in Thohoyandou, Limpopo Province, South Africa. Water SA 2019, 45, 183-189 .
AMA StyleOlatunde Durowoju, John Ogony Odiyo, Georges-Ivo Ekosse. Determination of isotopic composition of rainwater to generate local meteoric water line in Thohoyandou, Limpopo Province, South Africa. Water SA. 2019; 45 (2):183-189.
Chicago/Turabian StyleOlatunde Durowoju; John Ogony Odiyo; Georges-Ivo Ekosse. 2019. "Determination of isotopic composition of rainwater to generate local meteoric water line in Thohoyandou, Limpopo Province, South Africa." Water SA 45, no. 2: 183-189.
Geothermal springs and boreholes within the Soutpansberg Group were sampled and analysed for their major ion chemistry and stable isotope compositions in order to ascertain the possible sources and geochemical processes of the waters. The temperature of the geothermal springs ranges from 41 °C to 49 °C (thermal/hot waters) and 53 °C to 69 °C (scalding/hyperthermal waters). The major water types are Na-Cl and Na-HCO3, which are typical of marine and deep groundwaters influenced by ion-exchange processes. The hydrochemical parameters suggest that thermal gradient, carbonate weathering, mineral dissolution, ion exchange, and evaporation are the main geochemical processes controlling the geothermal springs. The δ18O and δ2H values vary from −5.82‰ to −4.82‰ for δ18O and −33.5‰ to −24.6‰ for δ2H for all the geothermal spring water. The isotopic ranges of the groundwater are relatively smaller and more depleted than those of rainwater (δ2H = −9.8‰ and δ18O = −2.7‰). The δ2H and δ18O signatures reveal a significant infiltration before evaporation. The δ2H and δ18O values further confirm that the waters are of meteoric origin, which implies that modern rainfall is the fundamental component of recharge derived from the infiltration of local precipitation with significant contribution of another type of water in the deeper part of the aquifer. These results provide further insight into this basement aquifer, which is a vital resource for the region.
Olatunde Samod Durowoju; Mike Butler; Georges-Ivo Ekosse Ekosse; John Ogony Odiyo. Hydrochemical Processes and Isotopic Study of Geothermal Springs within Soutpansberg, Limpopo Province, South Africa. Applied Sciences 2019, 9, 1688 .
AMA StyleOlatunde Samod Durowoju, Mike Butler, Georges-Ivo Ekosse Ekosse, John Ogony Odiyo. Hydrochemical Processes and Isotopic Study of Geothermal Springs within Soutpansberg, Limpopo Province, South Africa. Applied Sciences. 2019; 9 (8):1688.
Chicago/Turabian StyleOlatunde Samod Durowoju; Mike Butler; Georges-Ivo Ekosse Ekosse; John Ogony Odiyo. 2019. "Hydrochemical Processes and Isotopic Study of Geothermal Springs within Soutpansberg, Limpopo Province, South Africa." Applied Sciences 9, no. 8: 1688.
The aim of the present study was the paleoenvironmental reconstruction of the prevailing environment under which the Lwamondo and Zebediela kaolin deposits were formed. Hence, this study reports deuterium and oxygen stable isotope values and trace and rare earth element concentrations for two samples of kaolin. Upper continental crust-normalised trace-element patterns reveal that large ion lithophile elements and high-field-strength elements are generally depleted in Lwamondo and Zebediela kaolins, whereas transition trace elements are generally enriched in these kaolins. Upper continental crust-normalised rare earth element (REE) patterns show that there is a slight enrichment of heavy REEs (HREEs) compared to light REEs (LREEs) in these kaolins. The δ18O and δD stable isotope values for kaolinite from Lwamondo ranged from 17.4‰ to 19.1‰ and from −54‰ to 84‰, respectively, whereas those values for kaolinite from Zebediela varied from 15.6‰ to 17.7‰ and from −61‰ to –68‰ for δ18O and δD, respectively. The REE patterns and the content of other trace elements indicate ongoing kaolinitisation in the Lwamondo and Zebediela kaolins with minimum mineral sorting. The sources of the kaolins varied from basic to acidic and these were derived from an active margin tectonic setting. Lwamondo kaolin was deposited in an oxic environment whereas Zebediela kaolin was deposited under suboxic/anoxic conditions. Based on the δ18O and δD values of the kaolinite, they formed in a supergene environment at temperatures generally below 40 °C.
Avhatakali Raphalalani; Georges-Ivo Ekosse; John Odiyo; Jason Ogola; Nenita Bukalo. Trace Element and Stable Isotope Geochemistry of Lwamondo and Zebediela Kaolins, Limpopo Province, South Africa: Implication for Paleoenvironmental Reconstruction. Minerals 2019, 9, 93 .
AMA StyleAvhatakali Raphalalani, Georges-Ivo Ekosse, John Odiyo, Jason Ogola, Nenita Bukalo. Trace Element and Stable Isotope Geochemistry of Lwamondo and Zebediela Kaolins, Limpopo Province, South Africa: Implication for Paleoenvironmental Reconstruction. Minerals. 2019; 9 (2):93.
Chicago/Turabian StyleAvhatakali Raphalalani; Georges-Ivo Ekosse; John Odiyo; Jason Ogola; Nenita Bukalo. 2019. "Trace Element and Stable Isotope Geochemistry of Lwamondo and Zebediela Kaolins, Limpopo Province, South Africa: Implication for Paleoenvironmental Reconstruction." Minerals 9, no. 2: 93.
Increased interest in paleoenvironmental studies is a result of climatic changes occurring at present and predicted for the future. Such studies could be done using the stable isotope compositions (δ2H and δ18O) of kaolins, which provide knowledge on the paleoenvironmental conditions prevailing during the time of kaolinisation. In this study, the stable isotopic compositions of clay-size fraction of kaolins occurring in Cretaceous and Tertiary Formations of the Douala Sub-Basin in Cameroon are presented, with the aim of reconstructing the paleoenvironmental conditions of the Sub-Basin. To achieve this, the clay-size fraction (< 2 μm fraction) of 8 kaolinite-rich samples were analysed for their δ2H and δ18O compositions, and results were reported as part per mil (‰) relative to the SMOW standard. The δ18O values of kaolins found in the Cretaceous–Tertiary Formations of the Douala Sub-Basin varied between +18.2 and +21.0‰, whereas the δ2H values varied between –69 and –53‰. Nine of the eleven samples plotted on the right of the supergene–hypogene line. Five of these nine samples plotted very close to the kaolinite line, which represents the composition of kaolinite in equilibrium with meteoric water at 20 °C; suggesting a supergene weathering origin of these kaolins. The determination of the temperature of kaolinisation yielded mean formation temperatures of 22 ± 2 °C and 27 ± 6 °C for Cretaceous and Tertiary kaolins, respectively. Excluding the two samples falling in the hypogene field, averages of kaolinisation temperatures were 20 and 25 °C during the Cretaceous and Tertiary periods, respectively. These temperatures are slightly below the present mean annual temperature in Douala (27 °C), thereby suggesting that the climate was becoming warmer from the Cretaceous to the Present. Therefore, Douala had a cooler and rainy climate during the Cretaceous, and the climate is gradually becoming hotter and more humid, favouring the refinement of existing kaolins and the kaolinisation of kaolin-forming minerals in the Sub-Basin.
Nenita Bukalo; Georges-Ivo Ekosse; John Ogony Odiyo; Jason Ogola. Paleoclimatic implications of hydrogen and oxygen isotopic compositions of Cretaceous–Tertiary kaolins in the Douala Sub-Basin, Cameroon. Comptes Rendus Geoscience 2019, 351, 17 -26.
AMA StyleNenita Bukalo, Georges-Ivo Ekosse, John Ogony Odiyo, Jason Ogola. Paleoclimatic implications of hydrogen and oxygen isotopic compositions of Cretaceous–Tertiary kaolins in the Douala Sub-Basin, Cameroon. Comptes Rendus Geoscience. 2019; 351 (1):17-26.
Chicago/Turabian StyleNenita Bukalo; Georges-Ivo Ekosse; John Ogony Odiyo; Jason Ogola. 2019. "Paleoclimatic implications of hydrogen and oxygen isotopic compositions of Cretaceous–Tertiary kaolins in the Douala Sub-Basin, Cameroon." Comptes Rendus Geoscience 351, no. 1: 17-26.
The deliberate consumption of soil (geophagia) is reported to be an old practice and not restricted to any particular age, gender or race group. The aim of this study was to investigate the prevalence of geophagic practices and causative reasons for geophagia in the Sekhukhune area, Limpopo Province, South Africa. The study also discovered different geophagia sites where soil is obtained within the villages. Data was obtained through a cross-sectional study using 200 participants (males and females), between the ages of 18 and 65 years living in two Sekhukhune villages. Geophagia was reported by 172 (86%) consumers from the 200 participants, of which 143 (71.5%) in the study were mostly single and 164 (82%) only had secondary level of schooling. A total of 129 (74.9%) consumers reported consuming the soil for more than five years and 122 (71%) consumed more than once a day. The traditional name for edible soil is mobu in the villages. It was also reported that craving from 81 (47%) consumers was the main reason for the practice and 166 (96.4%) preferred to collect their soils in the wild. Of the 172 consumers, 112 (65.4%) did not know that the soil they were consuming could be harmful, however 107 (62%) reported that constipation might be caused by the practice. It became clear that the practice is entrenched in the cultural behaviour of the people of this area.
M.V. Phakoago; G.E. Ekosse; John Ogony Odiyo. The prevalence of geophagic practices and causative reasons for geophagia in Sekhukhune area, Limpopo Province, South Africa. Transactions of the Royal Society of South Africa 2019, 74, 19 -26.
AMA StyleM.V. Phakoago, G.E. Ekosse, John Ogony Odiyo. The prevalence of geophagic practices and causative reasons for geophagia in Sekhukhune area, Limpopo Province, South Africa. Transactions of the Royal Society of South Africa. 2019; 74 (1):19-26.
Chicago/Turabian StyleM.V. Phakoago; G.E. Ekosse; John Ogony Odiyo. 2019. "The prevalence of geophagic practices and causative reasons for geophagia in Sekhukhune area, Limpopo Province, South Africa." Transactions of the Royal Society of South Africa 74, no. 1: 19-26.
Olaonipekun Oyebanjo; Georges-Ivo Ekosse; John Ogony Odiyo. Hydrogen and oxygen isotope composition of selected Cretaceous and Paleogene/Neogene kaolins from Nigeria: Paleoclimatic inferences. Applied Clay Science 2018, 162, 375 -381.
AMA StyleOlaonipekun Oyebanjo, Georges-Ivo Ekosse, John Ogony Odiyo. Hydrogen and oxygen isotope composition of selected Cretaceous and Paleogene/Neogene kaolins from Nigeria: Paleoclimatic inferences. Applied Clay Science. 2018; 162 ():375-381.
Chicago/Turabian StyleOlaonipekun Oyebanjo; Georges-Ivo Ekosse; John Ogony Odiyo. 2018. "Hydrogen and oxygen isotope composition of selected Cretaceous and Paleogene/Neogene kaolins from Nigeria: Paleoclimatic inferences." Applied Clay Science 162, no. : 375-381.
Detrital zircon geochronology is a reliable provenance tool used to trace known zircon age populations from their metamorphic or igneous source to their present location in sedimentary basins. This paper presents U/Pb LA-SF-ICP-MS data of detrital zircons in Cretaceous-Tertiary kaolins in the Douala Sub-Basin in order to determine their provenance. The minimum ages of parent rocks which kaolinised were determined using U-Pb LA-SFICP-MS dating of zircons in the kaolin deposits. Four main zircon populations were identified from radiogenic dating: the 1st between 550 and 650 Ma, the 2nd between 950 and 1050 Ma, the 3rd around 1600 Ma and the 4th between 2800 and 3200 Ma. These four zircon populations belong to the Proterozoic (Neo-, Meso- and Paleoproterozoic) and the Archean. The minimum ages of parent rocks which contained the primary minerals that were kaolinised, reflected by the youngest weighted averages of zircon populations varied between 588 ± 2 Ma and 612 ± 2 Ma, all belonging to the Ediacaran Period (Neoproterozoic), respectively. Ages of zircons in Cretaceous-Tertiary kaolins suggested that the zircons formed during two main tectonic events: the Eburnean orogeny, during which older zircons crystallised and the Pan-African orogeny, during which younger zircons crystallised. The main identified sources of these zircons are the Archean Ntem Complex, the Paleoproterozoic Nyong Group and the Neoproterozoic Yaounde Group.
Nenita Bukalo; Georges-Ivo Ekosse; John Ogony Odiyo; Jason Ogola. U/Pb LA-SF-ICP-MS dating of detrital zircons in Cretaceous-Tertiary kaolins in the Douala Sub-Basin, Cameroon: A Neoproterozoic provenance. Journal of African Earth Sciences 2018, 147, 554 -568.
AMA StyleNenita Bukalo, Georges-Ivo Ekosse, John Ogony Odiyo, Jason Ogola. U/Pb LA-SF-ICP-MS dating of detrital zircons in Cretaceous-Tertiary kaolins in the Douala Sub-Basin, Cameroon: A Neoproterozoic provenance. Journal of African Earth Sciences. 2018; 147 ():554-568.
Chicago/Turabian StyleNenita Bukalo; Georges-Ivo Ekosse; John Ogony Odiyo; Jason Ogola. 2018. "U/Pb LA-SF-ICP-MS dating of detrital zircons in Cretaceous-Tertiary kaolins in the Douala Sub-Basin, Cameroon: A Neoproterozoic provenance." Journal of African Earth Sciences 147, no. : 554-568.
The geochemistry of the <2 μm fractions of Cretaceous-Tertiary Kaolins from Eastern Dahomey and Niger Delta Basins, Nigeria was investigated to infer their paleoenvironment, provenance, and tectonic settings using major, trace, and rare earth elements (REE). Twenty-eight (28) samples comprising of fifteen (15) Cretaceous and thirteen (13) Tertiary kaolins, respectively, were collected. Geochemical compositions of the <2 μm fractions were obtained using X-ray fluorescence (XRF) Spectrometry and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS) analytical methods. Weathering indices such as chemical index of alteration (CIA, 96.98-99.39) and chemical index of weathering (CIW, 98.95-99.89) suggested intense chemical weathering under a wet tropical climatic condition. Ni/Co, V/Ni ratios and bivariate plot of V versus Ni indicated that they were deposited under marine oxygen-poor environment which is consistent with the horst and graben structural framework model of the Eastern Dahomey and Niger Delta Basins. The major, trace and REE data suggest that these deposits were derived from predominantly felsic source rocks with contributions from intermediate source rocks. The geochemical discrimination plots showed that the Cretaceous and Tertiary kaolins have been deposited in passive margin tectonic settings.
O.L.A.O.N.I.P.E.K.U.N. Oyebanjo; Georges-Ivo Ekosse; J.O.H.N. Odiyo. Geochemical characterisation of the <2 μm fractions of cretaceous-tertiary kaolins from eastern dahomey and Niger delta basins, Nigeria: Implications on paleoenvironment, provenance, and tectonic settings. Journal of African Earth Sciences 2018, 147, 402 -410.
AMA StyleO.L.A.O.N.I.P.E.K.U.N. Oyebanjo, Georges-Ivo Ekosse, J.O.H.N. Odiyo. Geochemical characterisation of the <2 μm fractions of cretaceous-tertiary kaolins from eastern dahomey and Niger delta basins, Nigeria: Implications on paleoenvironment, provenance, and tectonic settings. Journal of African Earth Sciences. 2018; 147 ():402-410.
Chicago/Turabian StyleO.L.A.O.N.I.P.E.K.U.N. Oyebanjo; Georges-Ivo Ekosse; J.O.H.N. Odiyo. 2018. "Geochemical characterisation of the <2 μm fractions of cretaceous-tertiary kaolins from eastern dahomey and Niger delta basins, Nigeria: Implications on paleoenvironment, provenance, and tectonic settings." Journal of African Earth Sciences 147, no. : 402-410.
This study examines the mineral composition and kaolinite crystallinity of Cretaceous and Paleogene/Neogene kaolins from Nigeria based on X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy data of the
O.M. Oyebanjo; Georges-Ivo Ekosse; John Ogony Odiyo. Mineral Constituents and Kaolinite Crystallinity of the <2 μm Fraction of Cretaceous-Paleogene/Neogene Kaolins from Eastern Dahomey and Niger Delta Basins, Nigeria. Open Geosciences 2018, 10, 157 -166.
AMA StyleO.M. Oyebanjo, Georges-Ivo Ekosse, John Ogony Odiyo. Mineral Constituents and Kaolinite Crystallinity of the <2 μm Fraction of Cretaceous-Paleogene/Neogene Kaolins from Eastern Dahomey and Niger Delta Basins, Nigeria. Open Geosciences. 2018; 10 (1):157-166.
Chicago/Turabian StyleO.M. Oyebanjo; Georges-Ivo Ekosse; John Ogony Odiyo. 2018. "Mineral Constituents and Kaolinite Crystallinity of the <2 μm Fraction of Cretaceous-Paleogene/Neogene Kaolins from Eastern Dahomey and Niger Delta Basins, Nigeria." Open Geosciences 10, no. 1: 157-166.
As a step in evaluating the quality of Cretaceous-Tertiary kaolins of the Douala Sub-Basin, their mineralogical characteristics were determined. The X-ray diffractometry technique was used to identify and quantify the mineral phases present in bulk and smectite > illite, with mean values of 33.01 > 11.20 > 4.41 wt %; and 72.23 > 10.69 > 4.69 wt %, in bulk and <2 μm fractions, respectively. The kaolins, micromorphologically, consisted of pseudo-hexagonal and thin platy particles; swirl-textured particles; and books or stacks of kaolinite particles. Three main reactions occurred during heating of the kaolins: a low temperature endothermic reaction, observed between 48 and 109 °C; a second low temperature peak, observed between 223 and 285 °C; and a third endothermic peak was found between 469 and 531 °C. In addition, an exothermic reaction also occurred between 943 and 988 °C in some of the samples. The absence of primary minerals such as feldspars and micas in most of these kaolins is an indication of intensive weathering, probably due to the humid tropical climate of the region. The different morphologies suggested that these kaolins might have been transported. Therefore, a humid tropical climate was responsible for the formation of Cretaceous-Tertiary kaolins of the Douala Sub-Basin through intense weathering of surrounding volcanic and metamorphic rocks.
Nenita N. Bukalo; Georges-Ivo E. Ekosse; John Ogony Odiyo; Jason S. Ogola. Mineralogical characteristics of Cretaceous-Tertiary kaolins of the Douala Sub-Basin, Cameroon. Journal of African Earth Sciences 2018, 141, 130 -147.
AMA StyleNenita N. Bukalo, Georges-Ivo E. Ekosse, John Ogony Odiyo, Jason S. Ogola. Mineralogical characteristics of Cretaceous-Tertiary kaolins of the Douala Sub-Basin, Cameroon. Journal of African Earth Sciences. 2018; 141 ():130-147.
Chicago/Turabian StyleNenita N. Bukalo; Georges-Ivo E. Ekosse; John Ogony Odiyo; Jason S. Ogola. 2018. "Mineralogical characteristics of Cretaceous-Tertiary kaolins of the Douala Sub-Basin, Cameroon." Journal of African Earth Sciences 141, no. : 130-147.
The geochemical characteristics of selected kaolins from Cameroon and Nigeria are presented, with an attempt to elucidate on their possible industrial applications by comparing them to world-known kaolin deposits. Major oxides concentrations were subjected to factor analyses in interpreting their relationships. Geochemical indices, including chemical index of alteration (CIA), chemical index of weathering (CIW) and the index of compositional variability (ICV) were computed and plotted on binary and ternary diagrams to determine the intensity of weathering of the kaolins and discriminate their different source rock types. Kaolinite was the major phase, followed by quartz, illite and goethite as minor phases. Minerals in trace phases included smectite, anatase, muscovite, gibbsite, microcline, palygorskite and calcite. Mean abundances of major oxides in wt% were: SiO
Nenita N. Bukalo; Georges-Ivo Ekosse; John Ogony Odiyo; Jason S. Ogola. Geochemistry of Selected Kaolins from Cameroon and Nigeria. Open Geosciences 2017, 9, 600 -612.
AMA StyleNenita N. Bukalo, Georges-Ivo Ekosse, John Ogony Odiyo, Jason S. Ogola. Geochemistry of Selected Kaolins from Cameroon and Nigeria. Open Geosciences. 2017; 9 (1):600-612.
Chicago/Turabian StyleNenita N. Bukalo; Georges-Ivo Ekosse; John Ogony Odiyo; Jason S. Ogola. 2017. "Geochemistry of Selected Kaolins from Cameroon and Nigeria." Open Geosciences 9, no. 1: 600-612.
The structural order of Cretaceous-Tertiary kaolins of the Douala Sub-Basin in Cameroon was determined in this study. This was achieved using Fourier Transform Infrared spectroscopy (FTIR) with attenuated total reflectance (ATR) on the Bomkoul, Dibamba, Ediki, Logbaba, Missole and Yatchika kaolins. Transmittance spectra of 20 samples were recorded in the mid-infrared regions (MIR). Results show that most of the kaolins had the four distinguishable bands in the hydroxyl (OH) stretching region, though the second transmittance band (3670 cm
Nenita N. Bukalo; Georges-Ivo Ekosse; John Ogony Odiyo; Jason S. Ogola. Fourier Transform Infrared Spectroscopy of Clay Size Fraction of Cretaceous-Tertiary Kaolins in the Douala Sub-Basin, Cameroon. Open Geosciences 2017, 9, 407 -418.
AMA StyleNenita N. Bukalo, Georges-Ivo Ekosse, John Ogony Odiyo, Jason S. Ogola. Fourier Transform Infrared Spectroscopy of Clay Size Fraction of Cretaceous-Tertiary Kaolins in the Douala Sub-Basin, Cameroon. Open Geosciences. 2017; 9 (1):407-418.
Chicago/Turabian StyleNenita N. Bukalo; Georges-Ivo Ekosse; John Ogony Odiyo; Jason S. Ogola. 2017. "Fourier Transform Infrared Spectroscopy of Clay Size Fraction of Cretaceous-Tertiary Kaolins in the Douala Sub-Basin, Cameroon." Open Geosciences 9, no. 1: 407-418.
Nine geophagic material samples were analysed in order to characterise their mineralogical and elemental constituents, and infer on their health threats. Most abundant mineral in the samples was quartz, followed by smectite, kaolinite and muscovite in minor; and microcline, plagioclase, and goethite in trace quantities. Dominant major oxides were SiO
Georges-Ivo Ekosse; Veronica Ngole-Jeme; Makia L. Diko. Environmental Geochemistry of Geophagic Materials from Free State Province in South Africa. Open Geosciences 2017, 9, 1 .
AMA StyleGeorges-Ivo Ekosse, Veronica Ngole-Jeme, Makia L. Diko. Environmental Geochemistry of Geophagic Materials from Free State Province in South Africa. Open Geosciences. 2017; 9 (1):1.
Chicago/Turabian StyleGeorges-Ivo Ekosse; Veronica Ngole-Jeme; Makia L. Diko. 2017. "Environmental Geochemistry of Geophagic Materials from Free State Province in South Africa." Open Geosciences 9, no. 1: 1.
Fifty-seven samples of soils commonly ingested in South Africa, Swaziland, Democratic Republic of Congo (DRC), and Togo were analyzed for the concentrations of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), lead (Pb), manganese (Mn), nickel (Ni), and zinc (Zn) and their bioaccessibility in the human gastrointestinal tract. Bioaccessibility values were used to calculate daily intake, and hazard quotient of each trace element, and chronic hazard index (CHI) of each sample. Carcinogenic risk associated with As and Ni exposure were also calculated. Mean pseudo-total concentrations of trace elements in all samples were 7.2, 83.3, 77.1, 15.4, 28.6, 24.9, 56.1, 2.8, and 26.5 mg/kg for As, Cr, Mn, Co, Ni, Cu, Zn, Cd, and Pb, respectively. Percent bioaccessibility of Pb (13–49%) and Zn (38–56%) were highest among trace elements studied. Average daily intake values were lower than their respective reference doses for ell elements except for Pb in selected samples. Samples from DRC presented the highest health risks associated with trace element exposure with most of the samples having CHI values between 0.5 and 1.0. Some samples had higher than unacceptable values of carcinogenic risk associated with As and Ni exposure. Results indicate low trace element exposure risk from ingesting most of the soil samples.
Veronica Ngole-Jeme; Georges-Ivo Ekosse; Sandile Phinda Songca. An analysis of human exposure to trace elements from deliberate soil ingestion and associated health risks. Journal of Exposure Science & Environmental Epidemiology 2016, 28, 55 -63.
AMA StyleVeronica Ngole-Jeme, Georges-Ivo Ekosse, Sandile Phinda Songca. An analysis of human exposure to trace elements from deliberate soil ingestion and associated health risks. Journal of Exposure Science & Environmental Epidemiology. 2016; 28 (1):55-63.
Chicago/Turabian StyleVeronica Ngole-Jeme; Georges-Ivo Ekosse; Sandile Phinda Songca. 2016. "An analysis of human exposure to trace elements from deliberate soil ingestion and associated health risks." Journal of Exposure Science & Environmental Epidemiology 28, no. 1: 55-63.
The Limpopo Province is the location of 31% of South Africa’s geothermal springs. The springs at Siloam and Tshipise are among those springs which fall into the ‘scalding category’ with average temperatures of 67.7°C and 54.6°C, respectively. The aim of this study was to determine the horizontal variation in trace element concentrations and soil indicators in surface soil associated with the geothermal springs at Siloam and Tshipise. Results show that, in general, the trace element concentrations present in the soil decrease with horizontal distance from the springs. Water and soil samples were collected from May to July 2014, with the soil sampled at 0–15 cm depth at 5 m intervals in the horizontal distance from the geothermal spring. The physicochemical parameters of the water were determined as well as the trace elements. The soil samples were digested using microwave digestion and trace elements were determined using an inductively coupled plasmamass spectrometer (ICP-MS). Soil indicators – pH, soil organic matter (SOM) and soil water retention (SWR) – were also determined. The resulting data were subjected to both descriptive and factor analyses. Results showed only one factor determining the variation in geothermal water, attributed to the rock–water interaction in the deep aquifer (geology); two factors were obtained for variation in soil indicators and trace element concentrations, attributed to spring geology and the soil pedogenesis. There was a strong correlation between the trace elements and soil indicators at the 95% confidence level. There is generally a positive correlation between the trace elements and soil indicators if the soil pH, SOM and SWR are high; in these instances most of the trace elements in the soil will also be relatively high. A two-factors-without-replication ANOVA (p ˂ 0.05) showed that there is a significant difference in trace element concentrations at different distances.Keywords: geothermal springs, trace metals, soil indicators, rock-water interactions, soil pedogenesis
Olatunde Durowoju; John Ogony Odiyo; Georges-Ivo Ekosse. Horizontal variation in trace elements and soil characteristics at Siloam and Tshipise geothermal springs, Limpopo Province, South Africa. Water SA 2016, 42, 694 .
AMA StyleOlatunde Durowoju, John Ogony Odiyo, Georges-Ivo Ekosse. Horizontal variation in trace elements and soil characteristics at Siloam and Tshipise geothermal springs, Limpopo Province, South Africa. Water SA. 2016; 42 (4):694.
Chicago/Turabian StyleOlatunde Durowoju; John Ogony Odiyo; Georges-Ivo Ekosse. 2016. "Horizontal variation in trace elements and soil characteristics at Siloam and Tshipise geothermal springs, Limpopo Province, South Africa." Water SA 42, no. 4: 694.