Browsing by Author "Nyame, F."
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Item Geochemical and Sr‐Nd isotopic records of Paleoproterozoic metavolcanics and mafic intrusive rocks from the West African Craton: Evidence for petrogenesis and tectonic setting(Geological Journal, 2018-03) Sakyi, P.A.; Anum, S.; Su, B.X.; Nude, P.M.; Su, B.C.; Asiedu, D.K.; Nyame, F.; Kwayisi, D.Metavolcanics and mafic intrusive rocks of the Paleoproterozoic Birimian terrane in the southeastern part of the West African Craton, Ghana, were analyzed for major and trace elements and Nd and Sr isotopic data to constrain the geodynamic evolution of the Birimian Supergroup. The metavolcanic rocks consist of metabasalts, meta-andesites, and amphibolites, whereas the mafic intrusions are mainly gabbros, hornblendites, and dolerites. The rocks are tholeiitic in composition and show the classic features of arc magmatism. The metavolcanics display significant enrichments in large ion lithophile elements (LILE) and light rare earth elements, relative to high field strength elements (HFSE) and heavy rare earth elements. The multielement patterns of the rocks also show positive Pb, Ba, Th, and Sr and negative Nb, Ta, and Ce anomalies that are typical characteristics of subduction-related magmas. They also have La/Nb ratios <3 and La/Ta ratios <43 that are similar to other Archean and Birimian greenstone belts in West Africa. The rocks have εNd (2.1 Ga) values of -0.96 to +2.60, and Nd model ages of 2.24-2.51 Ga (TDM1) and 2.16-2.45 Ga (TDM2), indicating their juvenile character with possible contributions from pre-Birimian crustal materials in their sources. The εNd values suggest a depleted source and further indicate that they were probably produced in an almost entirely oceanic environment with minor influence from the continental crust. The Nd isotopic results are consistent with the island arc model, which views Paleoproterozoic terranes of the West African Craton in the context of subduction-accretion processes. Accordingly, these processes may have played a role in the formation of the Columbia supercontinent during the Paleoproterozoic (2.1-1.8 Ga) orogenic events.Item Geochemistry and geochronology of granitoids in the Kibi-Asamankese area of the Kibi-Winneba volcanic belt, southern Ghana(Journal of African Earth Sciences, 2015-02) Anum, S.; Sakyi, P.A.; Su, B.-X.; Nude, P.M.; Nyame, F.; Asiedu, D.; Kwayisi, D.In Ghana the West African Craton is represented by Birimian and Tarkwaian rocks with extensive granitoid bodies. Granitoids from Asamankese area of the Kibi-Winneba volcanic belt, southern Ghana were analysed for major and trace element contents and found to be characterised by highly-fractionated REE, enrichments, in LILE, and depletion in Nb, Ta and Sr. The LILE enrichment relative to strong Nb-Ta depression, indicates that these granitoids were emplaced in an active margin. Based on field relations, geochemical composition and geochronological data, the granitoids from the Kibi-Asamankese area can be divided into three types, namely; the Eburnean biotite granodiorite (2133-2127. Ma) and hornblende granodiorite (2147. Ma), and the Pre-Eburnean gneissic biotite granite (2193. Ma). The geochemical data of the studied rocks plot in the tholeiitic field, whereas on the A/CNK-A/NK diagram, they generally fall within the metaluminous field, with A/CNK values between 0.69 and 0.88. U-Pb dating of zircons in the granitoids yielded ages ranging from 2193 to 2127. Ma, which are among the oldest ages obtained from the granitoid plutons in Ghana. Such high-precision geochronological data indicate that magmatism occurred over a time-span of about 70. Ma. This provides further evidence that the period 2.1-2.2. Ga was one of the important stages of Birimian magmatism that led to the generation of the granitoids. From the above-mentioned ages, it is possible to link the geological activities to crustal processes and establish the cyclic geotectonic evolution in the West African Craton over time as part of an arc-back-arc basin system. © 2014 Elsevier Ltd.Item Gold mining in Ghana's forest reserves: A report on the current debate(Area, 2006-06) Hilson, G.; Nyame, F.This paper examines the debate surrounding a recent decision made by the Ghanaian government to permit gold exploration - and potentially, mining - in 'protected' forest reserves. In 2001, four mining companies were awarded mineral exploration concessions in forested regions of the country, and have since put forward applications to mine for gold. Notwithstanding the sharp divide in opinion on the issue, the continued uncertainty surrounding the implications of the proposed activities makes further research on the ground imperative in the short term. Work aiming to elicit indigenous perspectives on the projects, as well as research that facilitates dialogue between and/or among stakeholder parties, should be prioritized. © The Authors. Journal compilation © Royal Geographical Society (with The Institute of British Geographers) 2006.Item Leaching of trace metals from mixed electronic waste using four extraction methods(Science and Development, 2017) Donkor, A.; Owusu, G.; Banson, S.A.; Ziwu, C.; Bonzongo, J.; Nyarko, S.; Tawiah, R.; Asante, I.; Nyame, F.Rapid developments in technology in recent times, coupled with increasing demands for electronic products, have led to a rapid increase in electronic waste (e-waste) in the environment. The leaching of metals from e-wastes into the environment is a potential health and environmental hazard. The present study investigates the leaching potential of fourteen metals (Ag, Al, As, Ca, Cd, Cr, Cu, Fe, K, Mg, Na, Ni, Pb and Zn) in mixed waste printed circuit boards (PCBs) and plastic housing (PH) from recycling/dump sites. The assessment was carried out using rain water, deionized water, synthetic precipitation leaching procedure (SPLP) solution and seawater over a period of 192 hours at regular intervals. The data obtained was compared to TCLP and WET limits. The toxicity characteristic potential of the elements extracted by these solvents were in the order deionized water>rainwater>SPLP>seawater. The levels of the 14 elements studied were generally low and in varying concentrations, with Ca, K, Mg and Na being relatively higher in all the leaching fluids. The results further proved that leaching from PCBs and PH was a significant source of trace metals from recycling/dump sites. Therefore, proper handling and disposal of these waste materials should be encouraged to lessen their impact on the environment.Item Public Perception of E-Waste Management and Disposal Practices in Accra Metropolis, Ghana(Science and Development, 2017) Owusu, G.; Donkor, A.; Ziwu, C.; Nyarko, S.; Bonzongo, J.; Dubey, B.; Asante, I.; Nyame, F.The electrical/electronic industry is one of the fastest growing sectors in the world today. The increasing demand for newer electrical/electronic equipment and the shorter lifespan of these products leads to the generation of large volumes of e-wastes (electrical and electronic wastes) in the environment. Unlike the developed nations, there is lack of public awareness and proper legislation to effectively manage these wastes in most developing nations, including Ghana. In this study, a survey was carried out on 800 respondents to determine their knowledge of e-waste management practices and the effects on humans and the environment. The results generally revealed a low level of awareness, with most participants showing little or no interest in their environment. The majority of respondents identified reselling and recycling of used electrical and electronic equipment (UEEE) as the most appropriate and safe disposal methods. There was a correlation between level of education and knowledge of: (i) toxic chemicals in e-waste, (ii) human health and environmental impact and (iii) disposal methods for e-waste using a Chi-square test, a fact emphasized by Principal Component Analysis (PCA). Thus, there is the need for programmes to educate and create general awareness for this class of wastes as a potential source of pollutants.Item Water quality status of dugouts from five districts in Northern Ghana: Implications for sustainable water resources management in a water stressed tropical savannah environment(Environmental Monitoring and Assessment, 2009-07) Cobbina, S.J.; Anyidoho, L.Y.; Nyame, F.; Hodgson, I.O.A.This study was primarily aimed at investigating the physicochemical and microbial quality of water in 14 such dugouts from five districts in the northern region of Ghana. Results obtained suggest that except for colour, turbidity, total iron and manganese, many physicochemical parameters were either within or close to the World Health Organisation's acceptable limits for drinking water. Generally, colour ranged from 5 to 750 Hz (mean 175 Hz), turbidity from 0.65 to 568 nephelometric turbidity units (NTU; mean 87.9 NTU), total iron from 0.07 to 7.85 mg/L (mean 1.0 mg/L) and manganese from 0.03 to 1.59 mg/L (mean 0.50 mg/L). Coliform counts in water from all the dugouts in both wet and dry seasons were, however, above the recommended limits for drinking water. Total and faecal coliforms ranged from 125 to 68,000 colony forming units (cfu)/100 mL (mean 10,623 cfu/100 mL) and <1 to 19,000 cfu/100 mL (mean 1,310 cfu /100 mL), respectively. The poor microbial quality, as indicated by the analytically significant presence of coliform bacteria in all samples of dugout water, strongly suggests susceptibility and exposure to waterborne diseases of, and consequent health implications on, the many people who continuously patronise these vital water resources throughout the year. In particular, more proactive sustainable water management options, such as introduction to communities of simple but cost-effective purification techniques for water drawn from dugouts for drinking purposes, education and information dissemination to the water users to ensure environmentally hygienic practices around dugouts, may be needed. © Springer Science+Business Media B.V. 2010.