Institute of Applied Science and Technology

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    The Role of Quality Seed in Rice Production - A Case Study of the Dawhenya Irrigation Scheme
    (University of Ghana, 2018-05) Nwaleh, A. K. B.
    Rice, which is considered as one of the most agriculturally significant crops in the world, responsible for providing two thirds of the total calorie intake of more than 3 billion people in Asia and one third of the total calorie intake of mainly 1.5 billion people in Africa and Latin America is plagued by many difficulties in production particularly in developing countries. Though its consumption is on the rise in Ghana, domestic production has been reported to be disproportionate to consumption demands. The low domestic production figures are linked to the fact that many Ghanaian farmers use seeds of low quality. Since the rehabilitation of the Dawhenya irrigation scheme, by the Korean International Development Agency (KOICA) between 2011 and 2013 which cost US$ 3.6 million, the site has been facing declining yields in rice production with the project average yield falling from 6.7 t/ha to 5.2 t/ha within 3 cropping seasons. The dip in yield figures was attributed to many factors such as bad agronomic practices, high irrigation charges, the quality of water used in the cultivation of the crop and the unavailability of quality seeds. This study therefore aimed at examining the role that quality seeds used by farmers at the Dawhenya irrigation scheme play in the yield decline by weighing the quality of the seeds physically, conducting germination percentage tests, moisture content test and seed health status with that of the criteria recommended by International bodies. The mindset of the farmers was first evaluated to know their perception on what the actual cause of declining yield at the site is. Samples of the seeds of 30 randomly selected farmers were then taken to the National Seed Testing Laboratory at the Ghana Seed Inspectorate Division (GSID), Pokuase for the quality tests of the seeds. The analysis showed that the seeds used by the farmers (Farmer saved seeds) at the site was up to the required standards and in some cases above the standards in most areas of quality. It was therefore concluded that the quality of the seeds used in the cultivation of rice at the site was not a factor University of Ghana http://ugspace.ug.edu.gh iii that contributed to the perceived decline at the site and that the perception of the farmers which was largely attributed to the high cost of production of the commodity may be the cause of the yield decline in their respective fields at the Dawhenya Irrigation Scheme. Implications of this study may be that when steps are taken to reduce the cost of production of rice at this site, production of the commodity would increase and consequently improve rice production in the country.
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    Thermal Hydraulic and Safety Analysis of Heat Transfer and Distribution in the Ghana Research Reactor-1 (Gharr-1) Core Using Star-Ccm+ Cfd Code
    (University of Ghana, 2016-07) Mangena, S.; Emi, G.R.; Agbodemegbe, V.Y.; University of Ghana, College of Basic and Applied Sciences, Institute of Applied Science and Technology
    Operational power of a nuclear reactor core is limited by thermal considerations. In principle, the allowable core power is restricted by the rate at which the heat can be transferred from the fuel to the coolant. Unlike in conventional combustion facilities where the heat is released in gas-flows, heat in the nuclear reactor core is mainly released in the structural material. If not properly removed the structural materials inevitably melt causing release of radioactive material. STAR-CCM+ CFD code was used to perform thermal hydraulic analysis of the Miniature Neutron Source reactor also known as the Ghana Research Reactor-1 (GHARR-1). The reactor has a Highly Enriched Uranium (HEU) core consisting 344 fuel pins arranged in 10 multi-concentric circle layers at a pitch distance of 10.95 mm. The present study however considered only the first two concentric rings with varying power of 15 to 30kW. The choice of the first two concentric rings was informed by the results of the computation of local power peaking factors based on power densities. The result indicates that the maximum radial peaking factor of 2.02 occurred at the mid-plane of the core while the maximum axial peaking factor of 1.57 was at the region of the second ring. The extent of the domain considered in this work was also limited by the computational resources available. Analysis of the temperature, pressure, mass flow rate and turbulent intensity in the first two concentric rings was performed to assess the steady state Thermal hydraulic behaviour of GHARR-1 core under natural convection cooling. Computational simulation was performed at 15 and 30 kW at a fixed mass flow rate of 0.11 kg/s. The mass flow rate was varied from 0.11 to 0.15 kg/s in steps of 0.02 kg/s at a fixed power of 30 KW. Effective heat transfer and cooling of the reactor was achieved at the maximum coolant mass flow rate. Surface Average temperature increased along the flow channel from the inlet to the outlet in conformity with operating trends reported in the GHARR-1 Safety Analysis Report. The highest surface average temperature in the normal operating power range (15-30kW) was observed to be 296.21K at 30 kW and coolant mass flow rate of 0.11kg/s. The hottest channel is located between the inner and outer ring on the triangular pitch distance bounded by rods 4, 5 and 14. The hottest segment has a temperature of 301.85K and is located at an axial distance of 0.2020cm. This is below the maximum cladding Temperature of 333.15K hence the reactor is operating safely. Computed Distribution of the mass flow rate generated in the domain varies proportionally with the assigned inlet mass flow rate for the normal operating powers (15-30kW) A turbulence surge at the inlet due to instantaneous injection of fluid coupled with a drop as a result of development of the flow was observed. A general turbulence buildup was also observed as the flow develops and the fluid stabilises. Turbulent intensity was observed to peak at the upper part of the fuel rods consistent with the predictions of the GHARR-1 Safety Analysis Report. All computed accident situation temperatures were below the melting point of the U-Al alloy satisfying regulatory requirements for safe operations.
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    Study of Heat Transfer in Circular Tubes with Supercritical Fluid by the STAR-CCM+ CFD Code
    (University of Ghana, 2015-07) Woko, L. F.; Agbodemegbe, V. Y.; Debrah, S. K.; University of Ghana, College of Basic and Applied Sciences, Institute of Applied Science and Technology
    Supercritical Cooled-Water Reactor (SCWR) which is planned to be deployed by 2030 derives its concept from Light Water Reactors (Boiling Water Reactor (BWR), Pressurized Water Reactor (PWR) and Fossil Fired Coal Plant but with a simpler design. Due to the strong variations of density at supercritical pressure, the SCWR is likely to inherit some of the issues related to the LWR’s in terms of heat transfer (e.g. thermal crisis). This research was undertaken in order to better understand the phenomena of heat transfer as applied to SCWR and also to test the applicability of Reynolds-Average Navier-Stokes (STAR-CCM+ CFD code). Kim’s et al., (2005) data which employs supercritical CO2 as a simulant of water at 8 MPa was used to test the applicability. The computational simulation by STAR-CCM+ on the prediction of a 2-D axisymmetric heat transfer of carbon dioxide at supercritical pressure flowing upward through heated cross-section of a circular tube was performed with six (6) low-Reynolds number models; -epsilon AKN, EB, standard low- Re and V2F with two -ω turbulence models; SST and standard Wilcox with low y+ wall treatment. The results of heat fluxes of 20, 23, 30 and 40 kW/m2 and mass flux of 314 kg/m2s were compared to the experimental data of Kim et al., (2005). The Standard low- Reynolds turbulence models were seen to have better capabilities to predict the heat transfer behaviour of supercritical CO2 as observed in the experiment. The -ω models did not perform favourably in the prediction of heat transfer deterioration. The V2F turbulence model performed better than the other models quantitatively when compared to the experimental data. The results of the simulation has been found to be able to reproduce the general features exhibited in the experimental data even though they over predicted the observed heat transfer deterioration both quantitatively and qualitatively.
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    Chemical and Isotopic Composition of Rainwater in the Coastal, Forest and Mountainous Areas of Volta Region of Ghana
    (University of Ghana, 2014-07) Kretchy, S. M.; Akiti, T. T.; Adomako, D.
    Harvesting rainwater for domestic use is one of the oldest technologies developed by man. In Ghana, groundwater utilization challenges posed by dry wells and high levels of contaminants such as iron, fluoride and other minerals in some geological formations makes harnessing of rainwater for household use inevitable. Whiles researchers are looking for efficient ways of dealing with contaminants associated with these water sources, focus is gradually shifting to the development of enhanced methods for rainwater harvesting. In this study, rainwater samples were collected from Akatsi ( a coastal zone), Amedzofe (high altitude zone) and Kpando ( a forest zone) in the Volta region of Ghana and analyzed for the physico-chemical parameters such as pH, electrical conductivity (EC), total dissolved solids (TDS), colour, turbidity, alkalinity, Ca2+, K+, Na+, Mg2+, NO3-, NH4+, pH, Cl-, and SO42-. The results showed that, pH values of the Akatsi, Amedzofe and Kpando rainfall ranges from 5.40 to 6.85, 4.3 to 6.3 and 4.76 to 6.00 respectively. Amedzofe showed a relatively low pH with 13.70% ranging from 4 to 5, 82.40% of the rainfall events fell within pH of 5 to 6 and 3.90% had pH less than 7 but greater than 6. About 96.10% of the total rainfall events had pH less than 6. EC, TDS, turbidity and colour were generally low with higher values recorded at Akatsi while Amedzofe recorded the lowest values. The concentration of major ions and element-to-sodium ratios showed clear variations with higher levels found in Akatsi (coastal zone) and lower levels found in Amedzofe. Anion order of dominance in Akatsi, Kpando and Amedzofe are HCO3- >SO42- >Cl->NO3-, HCO3- >SO42- >Cl->NO3-and HCO3- >Cl-> SO42- >NO3- respectively, while cation order of dominance are Na+>Mg2+>Ca2+, Ca2+> Na+>Mg2+and Na+> Ca2+>Mg2+ for Akatsi, Amedzofe and Kpando respectively. Isotopic composition of rainwater was also determined for the three areas. Akatsi (coastal zone) presents high values of δ18O and δ2H, whereas rainwater in Amedzofe was characterized by low values of δ18O and δ2H, Kpando on the other hand was intermediately high. The Local Meteoric Water Line for the study area using rainfall greater than 20mm was defined as δ2H =7.453 δ18O + 8.621 (n=45; R2=0.907, rain > 20mm). Isotope fractionation in precipitation, including depletion in both δ18O and δ2H is primarily due to the rainout and the altitude effects with temperature effect being insignificant. The calculated altitude effect shows a gradual lapse rate of δ18O and δ 2H of about -0.2‰/100 m and -1.5 ‰/100 m for Akatsi and Amezofe respectively. Amedzofe and Kpando showed an altitude effect of -0.15‰ /100 m. and -2 ‰/100 m for δ18O and δ2H respectively. The groundwater in the study area is mainly of meteoric origin with different months of recharge. The plot of δ18O and EC shows that, mineral dissolution is the main factor controlling the groundwater salinization in Akatsi while Amedzofe and Kpando groundwater chemistry are mainly controlled by evaporation.
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    Study of the Radiological Impact of Small-Scale Mining Activities at Dunkwa-On-Offin in the Central Region, Ghana
    (University of Ghana, 2014-07) Emmanuel, M.; Darko, O. E.; Faanu, A.
    Small-scale (and artisanal) mining has been defined differently around the world. However, in Ghana, small-scale (gold) mining is defined as ―mining (gold) by any method not involving substantial expenditure by an individual or group of persons not exceeding nine in number or by a co-operative society made up of ten or more persons‖. The activities in the mining sector have increased in recent times and as at 2008, a total of 212 mining companies were awarded mining leases and exploration rights. These mining operations consequently turn out large volumes of solid and liquid wastes in the form of waste dams; slime dams, tailings dams, which could contain elevated levels of NORM. Small-scale mining activities pollute rivers and streams nearby that serve as sources of drinking water for communities downstream. These activities are common in the study area. The general aim of the studies is to assess the radiological exposure to members of the general public living in Dunkwa community and its surrounding communities due to NORMS as a result of the small-scale mining activities. Direct gamma spectrometry and iMatic P-F Gas-less Automatic Gross Alpha/Beta counter was used to determine the concentration of naturally occurring radionuclides 226Ra, 232Th and 40K, and gross alpha and gross beta activity concentration respectively in the soil and water samples. The mean values of the gross-α and gross-β activity concentrations in the water sources were 0.002±0.001 Bq/L and 0.029±0.016 Bq/L respectively which are also below the WHO recommended guideline values for drinking water. The gross-α and gross-β activity concentrations of most soil samples in the study area are below the activity concentration of the control sample. The mean activity concentrations measured for 226Ra (238U), 232Th and 40K in the soil samples were 25.4±11.1, 29.4±15.6 and 225.9±93.8 Bq/kg respectively. For the water samples the mean activity concentrations were 4.7±1.5, 2.7±0.4, 53.9±11.6 Bq/L for 226Ra (238U), 232Th and 40K respectively. The total annual effective dose to the public was estimated to be 0.95 mSv. The results obtained in the study area are within the recommended world average values with the exception of mean activity concentration 232Th and committed annual effective dose of the water samples. The results thus indicate an insignificant exposure of the general public. The radiological hazard assessment as a result of 226Ra (238U), 232Th and 40K were also established. The radium equivalent activity (Raeq), External hazard index (Hex) and Internal hazard index (Hin) varied in the range 32.8-173.4 Bq/kg, 0.1-0.4 and 0.1-0.6 with mean values of 87.0±38.9 Bq/kg, 0.2±0.1 and 0.3±0.1 respectively. The values of the Raeq, Hex and Hin are below the acceptable values. Hence soils from the study area that could be used for building purposes might not pose any significant radiological hazard.
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    Impact of Anthropogenic Activities on the Water Quality of Songor Lagoon, Ada, Greater Accra Region
    (University of Ghana, 2014-06) Sackey, J.; Adotey, D.; Dampare, S.
    Wetlands are vital ecosystems with important social, economic and environmental functions. The Ada Songor lagoon (located in the Dangbe East district, Greater Accra Region), is an internationally designated wetland (Ramsar site). Intense anthropogenic activities have impacted negatively on the quality of water and sediment in the lagoon. The study assessed the extent of heavy metal, pesticide residues and nutrients contamination of surface water and sediment in the Ada Songor Lagoon. The objective of the study was achieved through the determination of physico-chemical parameters [pH, temperature, electrical conductivity (EC), salinity, total dissolved solids (TDS), alkalinity, turbidity, biological oxygen demand (BOD), total hardness)]; the nutrients load (SO42-, PO43-, NO3-) using UV-Visible Spectrophotometry; major ions (Na+, K+, Ca2+, HCO3-); trace metals (Cd, Cr, Ni, Pb, Co, Zn, Cu, As and Hg) using Atomic Absorption Spectrometry (AAS); and, pesticides residues [organochlorines (OC’s), and synthetic pyrethroids by gas chromatography-electron capture detection (GC-ECD) and organophosphorus (OP’s) by gas chromatography-pulse flame photometric detection (GC-PFPD)]. Na and K contents were determined by Flame Emission Photometry. The water temperature (25.7 to 26.6 oC), fall in the range of 25 to 30 oC suitable for sustainability fish and aquatic organisms. The pH range (8.18 to 9.70) which is typical of coastal waters in Ghana is ideal for aquatic organisms. The TDS range (591 to 1,046 mg/L) is not ideal for water birds spawning since it make it harder for them to find food. BOD ranges from 1.19 to 5.35 mg/L. The pattern of ionic dominance in the lagoon during the present study was K+ > Na+ > Ca2+ > Mg2+. The cationic dominance pattern was
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    Dose Reduction in General Radiography While Maintaining Diagnostic Confidence for Selected Examinations in Selected Hospitals in the Ashanti Region, Ghana
    (University of Ghana, 2014-07) Amponsah, E.; Boadu, M.; Schandorf, C.; University of Ghana, College of Basic and Applied Sciences , Institute of Applied Science and Technology
    The objective of the study is to explore the potential for dose reduction in the selected X-ray facilities for the selected examinations and to ensure that images obtained after the reduction of dose are satisfactory for diagnosis.DAP were measured on a total of 327 patients for chest (PA), skull (PA/LAT), lumbar spine (AP/LAT), abdomen (AP) and pelvis (AP) examinations at COCL, MNDH, TAFH and MMGH. The effective dose incurred by patients per examination was estimated using a PCXMC version 1.5. In order to explore the potential for dose reduction, an anthropomorphic woman phantom was used. Seventy-five radiographs were obtained from the phantom studies at COCL, MNDH and TAFH for the image quality assessment. An experienced senior radiologist at the Korle-Bu Teaching Hospital performed the image quality assessment, which was based on the CEC 1996 image criteria. The range of the mean DAP and the effective dose recorded for the patient dose assessment for the selected examinations at the selected facilities is (21.1 – 752.1) μGy.m2 and (0.007 – 1.402) mSv respectively. The range of the DAP and the effective dose from the phantom studies were (15.1 – 200.1) μGy.m2 and (0.03 – 0.70) mSv respectively. In all, there was an overall average dose reduction of 49.7% in the DAP values for the selected examinations at COCL, MNDH and TAFH.
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    Extending the Shelf-Life of Cocoyam Leaves (Xanthosoma Sagittifolium) Through Blanching, Irradiation and Low Temperature Storage
    (University of Ghana, 2013-07) Afrifa, T. J.; Takyi, E. E. K.; Appiah, V.
    Cocoyam leaf (Xanthosoma sagiitifolium) (‘Kontommire‟) is arguably one of the most readily available and cheap indigenous leafy vegetable that is commonly consumed in Ghana. It is noted to be a good source of minerals, vitamins and soluble fibre when consumed in its fresh (not raw though) state. However, this vegetable is highly perishable. Dehydration methods and jute sack storage are usually used for its preservation. However, these lead to discolouration, loss of some nutrients, and exposure to microbial contamination thus reducing the general acceptability by consumers. In view of this, a study was conducted to process and preserve the leaves in their fresh state. Preservation methods investigated were: refrigeration, steam blanching, gamma irradiation and a combination of these methods. The effect of the various preservation methods on some physicochemical properties (moisture content and dry matter by gravimetric method, vitamin C (ascorbic acid) was determined by iodometric titration method, crude protein was determined by Kjeldahl method, colour change using a Minolta CR310 colorimeter , pH using the Mettler Toledo pH meter (model:T3KfTLH); phytochemical properties (total phenolic using the Folin ciocalteau method and total flavonoids using aluminium chloride colorimetric method); microbial quality (total viable count, total coliforms, yeast and moulds count using serial dilution); consumer acceptance using a 9-point hedonic scale to assess the colour, texture and odour. The best packaging material for effective storage was also investigated. Fresh, fully opened leaves of cocoyam which were two (2) weeks old were collected from the Biotechnology and Nuclear Agriculture Research Institute (BNARI) farm and used for the study. They were decontaminated by washing in fifty (50) % of brine solution and shredded and apportioned for the various treatments, packaged into zip-lock polyethylene bags and hermetically sealed bags. The shelf-life study lasted for three weeks with sampling at weekly intervals. Data obtained were analysed using the Statgraphics Centurion (16th edition). Results showed that, all the preservation methods as well as the packaging materials used increased the moisture content of the fresh cut cocoyam leaves significantly University of Ghana http://ugspace.ug.edu.gh xxi (p<0.05) during storage and reduced the dry matter content. However, the moisture content of samples stored in hermetically sealed polyethylene bag was higher than that of the zip-lock polyethylene bag. Also blanching and its combinations showed significantly (p<0.05) higher moisture content. Vitamin C content also reduced significantly (p<0.05) with all the preservation methods and packaging materials used. However, while the reduction was significantly low in refrigeration (4±2ᵒC) storage and its combinations, it was significantly high in ambient temperature (30±2ᵒC) storage. Radiation doses of 0.5 kGy to 2 kGy also significantly reduced vitamin C. Crude protein content in all the processed leaves increased significantly (p<0.05) during storage but was significantly higher in samples stored in hermetically sealed polyethylene bag. The colour of all the preserved cocoyam leaves was significantly affected by storage. However, the control and samples irradiated at 0.5kGy did not significantly affect the green colour but doses of 1 kGy, 1.5 kGy and 2 kGy reduced the yellowing of the cocoyam leaf under refrigeration storage. Storage increased total phenolic and total flavonoid content in all preservation methods used but had significance only under refrigeration storage and also irradiation dose of 1.5 kGy recorded the highest amount during storage. Microbiological quality assessment of the processed leaves also showed that blanching treatment significantly reduced the total viable count of the cocoyam leaf but increased the yeast and mould growth when stored for longer period. Samples stored in hermetically sealed bag package and ambient temperature (30 ᵒC) also had increase in the total viable count, yeast and mould count and total coliform count during storage. However, refrigeration after irradiation at 0.5 kGy to 1.5 kGy recorded a less count of microbial load in samples stored in hermetically sealed polyethylene bag after two weeks of storage. Pseudomonas fluorescens and Pseudomonas viridiflava, and Citrobacter spp were identified in samples stored by refrigeration.Sensory evaluation of the processed leaves showed that samples stored in zip-lock polyethylene bag were the most acceptable. Refrigeration alone in combination with radiation dose of 0.5 kGy and 1 kGy preserved the cocoyam leaf for three Cocoyam leaf (Xanthosoma sagiitifolium) (‘Kontommire‟) is arguably one of the most readily available and cheap indigenous leafy vegetable that is commonly consumed in Ghana. It is noted to be a good source of minerals, vitamins and soluble fibre when consumed in its fresh (not raw though) state. However, this vegetable is highly perishable. Dehydration methods and jute sack storage are usually used for its preservation. However, these lead to discolouration, loss of some nutrients, and exposure to microbial contamination thus reducing the general acceptability by consumers. In view of this, a study was conducted to process and preserve the leaves in their fresh state. Preservation methods investigated were: refrigeration, steam blanching, gamma irradiation and a combination of these methods. The effect of the various preservation methods on some physicochemical properties (moisture content and dry matter by gravimetric method, vitamin C (ascorbic acid) was determined by iodometric titration method, crude protein was determined by Kjeldahl method, colour change using a Minolta CR310 colorimeter , pH using the Mettler Toledo pH meter (model:T3KfTLH); phytochemical properties (total phenolic using the Folin ciocalteau method and total flavonoids using aluminium chloride colorimetric method); microbial quality (total viable count, total coliforms, yeast and moulds count using serial dilution); consumer acceptance using a 9-point hedonic scale to assess the colour, texture and odour. The best packaging material for effective storage was also investigated. Fresh, fully opened leaves of cocoyam which were two (2) weeks old were collected from the Biotechnology and Nuclear Agriculture Research Institute (BNARI) farm and used for the study. They were decontaminated by washing in fifty (50) % of brine solution and shredded and apportioned for the various treatments, packaged into zip-lock polyethylene bags and hermetically sealed bags. The shelf-life study lasted for three weeks with sampling at weekly intervals. Data obtained were analysed using the Statgraphics Centurion (16th edition). Results showed that, all the preservation methods as well as the packaging materials used increased the moisture content of the fresh cut cocoyam leaves significantly University of Ghana http://ugspace.ug.edu.gh xxi (p<0.05) during storage and reduced the dry matter content. However, the moisture content of samples stored in hermetically sealed polyethylene bag was higher than that of the zip-lock polyethylene bag. Also blanching and its combinations showed significantly (p<0.05) higher moisture content. Vitamin C content also reduced significantly (p<0.05) with all the preservation methods and packaging materials used. However, while the reduction was significantly low in refrigeration (4±2ᵒC) storage and its combinations, it was significantly high in ambient temperature (30±2ᵒC) storage. Radiation doses of 0.5 kGy to 2 kGy also significantly reduced vitamin C. Crude protein content in all the processed leaves increased significantly (p<0.05) during storage but was significantly higher in samples stored in hermetically sealed polyethylene bag. The colour of all the preserved cocoyam leaves was significantly affected by storage. However, the control and samples irradiated at 0.5kGy did not significantly affect the green colour but doses of 1 kGy, 1.5 kGy and 2 kGy reduced the yellowing of the cocoyam leaf under refrigeration storage. Storage increased total phenolic and total flavonoid content in all preservation methods used but had significance only under refrigeration storage and also irradiation dose of 1.5 kGy recorded the highest amount during storage. Microbiological quality assessment of the processed leaves also showed that blanching treatment significantly reduced the total viable count of the cocoyam leaf but increased the yeast and mould growth when stored for longer period. Samples stored in hermetically sealed bag package and ambient temperature (30 ᵒC) also had increase in the total viable count, yeast and mould count and total coliform count during storage. However, refrigeration after irradiation at 0.5 kGy to 1.5 kGy recorded a less count of microbial load in samples stored in hermetically sealed polyethylene bag after two weeks of storage. Pseudomonas fluorescens and Pseudomonas viridiflava, and Citrobacter spp were identified in samples stored by refrigeration.Sensory evaluation of the processed leaves showed that samples stored in zip-lock polyethylene bag were the most acceptable. Refrigeration alone in combination with radiation dose of 0.5 kGy and 1 kGy preserved the cocoyam leaf for three weeks with minimal effect whereas blanching, irradiation only and ambient temperature storage preserved the leaf for only a week. It is recommended that cut-leafy vegetables should be preserved by packaging in zip-lock polyethylene bags and stored in a refrigerator at a temperature of 4± weeks with minimal effect whereas blanching, irradiation only and ambient temperature storage preserved the leaf for only a week. It is recommended that cut-leafy vegetables should be preserved by packaging in zip-lock polyethylene bags and stored in a refrigerator at a temperature of 4±2ᵒC
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    Hydrogeochemistry and Isotopic Study of the Origin of Underground Mine Water at Golden Star Bogoso/Prestea Limited (New Century Mines)
    (University of Ghana, 2014-07) Gibrilla, I.; AKITI, T. T.; Adotey, K. D.;
    Hydrogeochemical study of the origin of underground mine water at Golden Star Bogoso/ Prestea Limited (New Century Mines) was carried out to determine the geochemical processes controlling surface water, groundwater and underground mine water and to identify the source of recharge to the underground water in the mines; investigate the hydrochemical facies of groundwater in the various aquifers (gallaries), and identify the relationship between surface water and groundwater, and underground mine water using hydrogeochemistry and stable isotope technique. Water from seventeen (17) surface water bodies, ten (10) hand-dug wells, eleven (11) boreholes and twenty-one (21) underground mine water samples were collected within Prestea in the Prestea-Huni Valley district of Western Region of Ghana between October 2013 and March 2014.The objectives of the study was achieved through the determination of pH, temperature, TDS, salinity, alkalinity, electrical conductivity, anions (SO42-, HCO3-, Cl-, PO43-, NO3-), major cations (Ca2+, Mg2+, Na+, K+) and trace elements (As, Cd, Cu, Fe, Mn, Pb and Zn). Arsenic,(As), was determined by Hydride Generation Atomic Absorption Spectrometry (HG-AAS). Levels of Cd, Cu, Fe, Mn, Mg, Pb and Zn were determined by Flame Atomic Absorption Spectrometry (FASS). The contents of Na+ and K+ were determined by Flame Photometry. Measurement of the levels of SO42-, PO43- and NO3- were achieved by UV-Visible spectrophotometry. Titrimetry was used for the determination of alkalinity, HCO3- and Cl-. Temperature, pH, Conductivity, Salinity and Total Dissolved Solids (TDS) of the surface water, groundwater and underground mine water were all assessed. The stable isotopes (δ2H and δ18O) compositions of the waters were determined using the Liquid-Water Isotope Analyzer [based on Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) via laser absorption]. The determined Levels of major cations (in ranges, meq/L) for the various waters were as follows: Surface Water: Ca [0.64-33.00], Mg [0.44-18.87], Na [0.12-5.59] and K [0.01-0.24]; Groundwater: Ca [1.01-5.39], Mg [0.76-2.32], Na [0.61-3.57] and K [0.11-3.57]; Underground mine water: Ca [5.91-43.00], Mg [3.61-14.50], Na [0.28-4.14] and K [0.83-0.96];.The determined Levels of major anions (in ranges, meq/L) for the various waters were as follows: Surface Water: SO4 [3.00-49.30], HCO3 [0.94-9.02], Cl [0.64-3.28], PO4 [0.01-3.06] and NO3 [0.01-0.17]; Groundwater: SO4 [2.15-5.96], HCO3 [0.28-2.38], Cl [0.69-3.89], PO4 [0.01-2.00] and NO3 [0.01-1.36]; Underground mine water SO4 [5.48-8.98], HCO3 [2.22-8.02], Cl [0.16-6.90], PO4 [0.10-3.23] and NO3 [0.08-0.43]. Strong correlation between HCO3- and SO42- demonstrate the formation of H2SO4 while groundwater and underground mine water traversing through pyrite bearing shale may dissolve heavy metals into groundwater. The variation of surface water, groundwater and underground mine water hydrogeochemistry revealed the dominance of Ca2+ > Mg2+ > Na+ > K+ as relative abundance of cation, and the dominance of relative anions SO42- > HCO3- > Cl- > PO43-> NO3-. The Piper trilinear diagram indicated water types from GSBPL (NCM) corresponded to the NaCl or Na - HCO3 – Cl, Ca – Mg – SO4 - Cl (water type) and mixed water type Ca – Mg – HCO3 – Cl. The study approach includes geochemical analysis and conventional graphical plots (Bivariate) of the hydrochemical data to assess the geochemical evaluation of processes. The result suggested different natural hydrogeochemical processes such as simple ion exchange, leaching and dissolution, evaporation and oxidation-reduction are the key factors. The influence on the species of groundwater and underground mine water chemistry is the leaching and dissolution of weathered rock with limited cation ion (reverse ion exchange) at few locations. Evaporation and oxidation-reduction are not among the major hydrochemical processes controlling the hydrochemistry of groundwater and underground mine water. Gibbs diagram also confirms the dominant process as the leaching and dissolution of minerals. Stable isotope composition measurements (in ranges ‰) for surface water [δ18O (-2.16 to +0.47); δ2H(-6.66 to +3.02)], hand-dug wells [δ18O (-2.28 to -0.87); δ2H(-6.48 to +0.58)], boreholes [δ18O (-2.23 to -0.48); δ2H(-8.88 to -1.68)] and underground mine water [δ18O (-2.22 to -0.95 ); δ2H(-8.54 to -1.00)]. This result indicates that stable isotopes (δ18O and δ2H) in the water samples from the GSBPL (NCM) clustered closely along the Global Meteoric Water Line (GMWL), suggesting an integrative and rapid recharge from meteoric origin (rainfall). Consequently, majority of the water samples are mainly meteoric water with little or no isotopic variations. Finally, recharging relationships were identified for these water samples; groundwater at Himan [borehole (HBH2)] and River Ankobra [ARaW (DS)]; surface water at Prestea [PUWF (DS)] and underground mine water at Prestea Central Shaft [UD-17F]; and surface water at Ankobra [ASP] and Prestea [PUWM(MS)], a borehole at Prestea [PBH6] and underground mine water at Prestea Central Shaft [UD-17B].
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    Hydrogeochemistry and Isotopic Study of the Origin Of Underground Mine Water At Golden Star Bogoso/Prestea Limited (New Century Mines)
    (University, 2014-07) Gibrilla, I.; Akiti, T. T.; Adotey, K.D.
    Hydrogeochemical study of the origin of underground mine water at Golden Star Bogoso/ Prestea Limited (New Century Mines) was carried out to determine the geochemical processes controlling surface water, groundwater and underground mine water and to identify the source of recharge to the underground water in the mines; investigate the hydrochemical facies of groundwater in the various aquifers (gallaries), and identify the relationship between surface water and groundwater, and underground mine water using hydrogeochemistry and stable isotope technique. Water from seventeen (17) surface water bodies, ten (10) hand-dug wells, eleven (11) boreholes and twenty-one (21) underground mine water samples were collected within Prestea in the Prestea-Huni Valley district of Western Region of Ghana between October 2013 and March 2014.The objectives of the study was achieved through the determination of pH, temperature, TDS, salinity, alkalinity, electrical conductivity, anions (SO42-, HCO3-, Cl-, PO43-, NO3-), major cations (Ca2+, Mg2+, Na+, K+) and trace elements (As, Cd, Cu, Fe, Mn, Pb and Zn). Arsenic,(As), was determined by Hydride Generation Atomic Absorption Spectrometry (HG-AAS). Levels of Cd, Cu, Fe, Mn, Mg, Pb and Zn were determined by Flame Atomic Absorption Spectrometry (FASS). The contents of Na+ and K+ were determined by Flame Photometry. Measurement of the levels of SO42-, PO43- and NO3- were achieved by UV-Visible spectrophotometry. Titrimetry was used for the determination of alkalinity, HCO3- and Cl-. Temperature, pH, Conductivity, Salinity and Total Dissolved Solids (TDS) of the surface water, groundwater and underground mine water were all assessed. The stable isotopes (δ2H and δ18O) compositions of the waters were determined using the Liquid-Water Isotope Analyzer [based on Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS). via laser absorption]. The determined Levels of major cations (in ranges, meq/L) for the various waters were as follows: Surface Water: Ca [0.64-33.00], Mg [0.44-18.87], Na [0.12-5.59] and K [0.01-0.24]; Groundwater: Ca [1.01-5.39], Mg [0.76-2.32], Na [0.61-3.57] and K [0.11-3.57]; Underground mine water: Ca [5.91-43.00], Mg [3.61-14.50], Na [0.28-4.14] and K [0.83-0.96];.The determined Levels of major anions (in ranges, meq/L) for the various waters were as follows: Surface Water: SO4 [3.00-49.30], HCO3 [0.94-9.02], Cl [0.64-3.28], PO4 [0.01-3.06] and NO3 [0.01-0.17]; Groundwater: SO4 [2.15-5.96], HCO3 [0.28-2.38], Cl [0.69-3.89], PO4 [0.01-2.00] and NO3 [0.01-1.36]; Underground mine water SO4 [5.48-8.98], HCO3 [2.22-8.02], Cl [0.16-6.90], PO4 [0.10-3.23] and NO3 [0.08-0.43]. Strong correlation between HCO3- and SO42- demonstrate the formation of H2SO4 while groundwater and underground mine water traversing through pyrite bearing shale may dissolve heavy metals into groundwater. The variation of surface water, groundwater and underground mine water hydrogeochemistry revealed the dominance of Ca2+ > Mg2+ > Na+ > K+ as relative abundance of cation, and the dominance of relative anions SO42- > HCO3- > Cl- > PO43-> NO3-. The Piper trilinear diagram indicated water types from GSBPL (NCM) corresponded to the NaCl or Na - HCO3 – Cl, Ca – Mg – SO4 - Cl (water type) and mixed water type Ca – Mg – HCO3 – Cl. The study approach includes geochemical analysis and conventional graphical plots (Bivariate) of the hydrochemical data to assess the geochemical evaluation of processes. The result suggested different natural hydrogeochemical processes such as simple ion exchange, leaching and dissolution, evaporation and oxidation-reduction are the key factors. The influence on the species of groundwater and underground mine water chemistry is the leaching and dissolution of weathered rock with limited cation ion (reverse ion exchange) at few. locations. Evaporation and oxidation-reduction are not among the major hydrochemical processes controlling the hydrochemistry of groundwater and underground mine water. Gibbs diagram also confirms the dominant process as the leaching and dissolution of minerals. Stable isotope composition measurements (in ranges ‰) for surface water [δ18O (-2.16 to +0.47); δ2H(-6.66 to +3.02)], hand-dug wells [δ18O (-2.28 to -0.87); δ2H(-6.48 to +0.58)], boreholes [δ18O (-2.23 to -0.48); δ2H(-8.88 to -1.68)] and underground mine water [δ18O (-2.22 to -0.95 ); δ2H(-8.54 to -1.00)]. This result indicates that stable isotopes (δ18O and δ2H) in the water samples from the GSBPL (NCM) clustered closely along the Global Meteoric Water Line (GMWL), suggesting an integrative and rapid recharge from meteoric origin (rainfall). Consequently, majority of the water samples are mainly meteoric water with little or no isotopic variations. Finally, recharging relationships were identified for these water samples; groundwater at Himan [borehole (HBH2)] and River Ankobra [ARaW (DS)]; surface water at Prestea [PUWF (DS)] and underground mine water at Prestea Central Shaft [UD-17F]; and surface water at Ankobra [ASP] and Prestea [PUWM(MS)], a borehole at Prestea [PBH6] and underground mine water at Prestea Central Shaft [UD-17B].