School of Nuclear and Allied Sciences
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Item Identification of Harmful Algal Blooms (HABs) Toxins in Seawater and Shellfish along the Coast of Ghana(University Of Ghana, 2019-07) Denutsui, D.Algal toxins can accumulate in fish and shellfish in the marine environment and thus cause these essential seafood products to be poisoned. The toxins and the algae containing them are routinely surveyed in Europe, North America, Japan and other developing countries. Interestingly, there is scarce or no information on the occurrence of toxin-causing algae in most African nations, including Ghana, apart from the North African countries and South Africa. The study identified and evaluated the distribution of harmful and potentially toxic phytoplankton causing harmful blooms of algae; the distribution of harmful phytoplankton along the coast of Ghana was evaluated. This was achieved through: (i) identification and characterization of harmful and potentially toxic phytoplankton species along the Central Coastline of Ghana; (ii) assessment of the distribution of the harmful phytoplankton; (iii) evaluation of the influence of the environmental driving factors {(Temperature, DO, Nutrients [PO43-, NO3-, SiO4] and Trace Elements [Zn & Fe]} on the distribution of HABs in Ghanaian Waters; (v) evaluation of the levels of iron (Fe) and zinc (Zn) in seawater and Hg, Mn, Cu, Zn, Fe and Cd in algae and establish the correlation between the levels of the essential elements and the presence of algae; (vi) isolation of the potentially Harmful Algal Bloom(HABs) species and assessment the level of toxicity of successful cultures and; (vii) investigation of the toxin effects of HABs in selected shellfish (Oysters, Bloody cockle and Clams) [Profiling of Toxins]. Seawater samples from five beaches (Tema, Accra Lighthouse, Bortianor-Tsokomey, Gomoa Nyanyanor and Ekumfi-Narkwa) were collected monthly between January 2014 to February 2018. Diatoms generally dominated the phytoplankton community; however, twelve (12) harmful species which are mostly thecate dinoflagellates. Five of the identified species (Lingulodinium polyedra, Gonyaulax spinifera, Dinophysis caudata, Dinophysis fortii, Alexandrium spp) were toxin producers (potentially causing diarrheic and paralytic shellfish poisoning). With the aid of the Ocean Data View and SPSS software, it was observed that temperature, pH, dissolved oxygen, phosphate, nitrate, zinc and Fe were the environmental driving forces influencing the availabilities of the harmful algal species. The densities of species varied seasonally (wet and dry). Critical densities (6200 cells/L) of Lingulodinium polyedra were recorded in December 2016 at Gomoa Nyanyanor; indicating its abundance in the five study areas. Preliminary observations from the study revealed the possible presence of Alexandrium spp, one of the most toxic genera among the HABs species. Principal Component Analysis (PCA) used to establish possible associations between algae and the physicochemical parameters revealed two distinct clusters corresponding to the sampling seasons (wet and dry seasons). The wet season (upwelling), established proliferation of diverse species whilst in the dry season less diverse species proliferated, but with high densities. Successful isolation and cultures of Alexandrium sp, Prorocentrum sp, Prorocentrum micans, Levanderina fissa and Coolia sp were achieved. Prorocentrum micans, Levanderina fissa and Coolia canarensis were successfully identified to species level by DNA sequencing. Toxin profile of successful cultures of Alexandrium sp, Prorocentrum sp, and Coolia sp, as well as of shellfish (Oysters, Bloody cockle and Clams) were ascertained. Three toxins [two (2) Paralytic Shellfish Poisoning) toxins, i.e. GTX2,3 GTX1,4; and one (1) Diarrheic Shellfish Poisoning toxin (an okadaic acid)] were identified in algae. A strain of Alexandrium spp was found to contain two gonyautoxins (GTX2,3) with 1.875×10-6 ng/cell and GTX1,4 with 1.502×10-4 ng/cell; while Prorocentrum spp were found to have toxicity of 2.65×10-4 ng/cell okadaic acids. Seven (7) bloody cockle samples tested positive to lipophilic toxins, Okadaic acids (OA) and Dinophysistoxins (DTX2). The levels of okadaic acids and dinophysistoxins ranges between 16 to 19 μgOA/kg and 3-6 μg OA/kg respectively. Three Bloody Cockle samples tested positive for traces of Paralytic Shellfish Poisoning toxins, Gonyautoxins (GTX2,3) and decarbamoylsaxitoxin (dcSTX). Interestingly, lipophilic toxins were identified in Ghanaian coastal waters. Okadaic acid and Dinophysistoxin (DTX2) quantified in bloody cockles may be attributed to Dinophysis species, although a partial contribution by Prorocentrum species cannot be ignored. The average concentration of dissolved Zn and Fe in studied coastal waters ranged from 0.021 to 0.23 mg/L and 0.05 to 0.204 mg/L, respectively. The highest concentrations were recorded at Gomoa Nyanyanor and Tema, while Accra Light House had the lowest levels. Studied coastal waters with high Zn and Fe concentrations showed corresponding high concentrations of phytoplankton species. The coastal water of Accra Light House with low levels of Zn and Fe showed low counts of phytoplankton. From the results, among the metals analysed for, the concentration of Cd was found to be below the detection limit (Cd<0.006). Mercury concentration detected from the total microalgae ranged from 10.05 to 18.29 (μg/kg). Other metals concentrations in the microalgae were in the ranges of 162.00 to 4418.90 (μg/kg) for Zn, 4533 to 24567 (μg/kg) for Fe and 225.10 to 2121.46 (μg/kg) for Mn. and 154.50 to 497.90 (μg/kg) respectively. Overall, the study identified the presence species of harmful algal blooms and biotoxins in the studied portion of the Ghanaian coastal waters. Apart from Accra Light House were just minute traces of harmful algal blooms species were present, the rest of the studied coastal waters had HABs well distributed. Generally, biotoxins were not identified in shellfish from the studied waters, except Ekumfi Narkwa were biotoxins were identified in only bloody cockles.Item Studies of Rare Earth Elements and Associated Radioactivity in the Coastal Sand of the Central and Western Regions of Ghana(University of Ghana, 2017-07) Abey, J.A.Beach sands are known host of different heavy minerals, which occur mostly as placer deposits and are of great importance to the electronics, metallurgy, medical, defense, and automobile industries. Typical examples of such heavy minerals are the rare earth-associated minerals (e.g. monazite, bastnaesite, xenotime and euxenite). Some of these rare earth elements-containing ores are known to occur in association with naturally occurring radioactive uranium (U-238) and thorium (Th-232). Limited studies are available on identification of rare earth element fingerprints in the coastal sands of Ghana. Also, the relationship between the Naturally Occurring Radioactive Materials (NORMs) and the Rare Earth Elements (REEs) in Ghanaian coastal sands has not been well studied. The study developed an analytical procedure for mapping out the composition of rare earth elements in beach sands via the pathfinder role of naturally occurring radioactivity along the coast of the Central and Western regions of Ghana. This was achieved through: (i) assessment of naturally occurring radionuclides (238Th, 232Th and 40K) using Gamma Spectrometry and ascertaining the presence of REEs-associated minerals using bromoform (density = 2.89 g/cm³) prior to petrography of the heavy mineral concentrates; (ii) investigation of REEs in coarse, medium and fine fractions using Lithium Metaborate Fusion Method using Inductively Coupled Plasma Mass Spectrometry (ICP-MS); (iii) development of chemical method in the separation of selected REEs (Pr, Nd, Sm, Eu); and (iv) establishment of geospatial distribution pattern to aid exploration of REEs minerals. Beach sand samples were collected from 15 locations in the Central region (Gomoa Fetteh, Senya Beraku, Winneba, Mankwadze, Apam, Mumford, Dago, Akra, Ekumpoano, Edumafa, Anomabu, Cape Coast, Elmina, Dutch Komenda and Kafodzizi) and 10 locations in the Western region (Shama, Abuesi, Sekondi, Takoradi, Cape Three Points, Egyembra, Axim, Esiama and Sanzule) along the coastline of Southwestern Ghana. The average concentrations of 238U, 232Th and 40K in the beach sands of the Central and Western regions of Ghana were found to contain the United Nations Scientific Committee on Effects of Atomic Radiation (UNSCEAR) recommended permissible levels (35; 30; and 400 Bq/Kg respectively) for radionuclides; with mean activity concentrations (ranges) of 1.3 ± 0.47 to 31.50± 3.31 Bq/Kg (238U); 0.7± 0.04 to 71.70± 4.55 Bq/Kg (232Th); 73.9± 6.72 to 1775.5± 28.35 (40K) for the Central region. In the Western region, the mean activity concentration ranged fom 1.0 ± 0.03 to 5.6± 0.24 Bq/Kg (238U); 0.8± 0.04 to 3.8± 0.14 Bq/Kg (232Th); and 18.6± 0.23 to 343.2± 18.35 (40K). Beach sand dose rate in the Central region and Western region ranged from 4.13 to 132.39 (nGy/hr) and 1.78 to 19.32 (nGy/hr) respectively; with a total average across the two regions being 11.40 (nGy/hr). The annual effective dose in the Central region ranged from 0.0051 to 0.1624, while that for the Western region ranged from 0.002 to 0.024; total average for the two regions was 0.014 mSv/Yr. High radioactivity levels (Bq/Kg) (238U; 232Th; 40K; Raeq) observed in the beach sands of Dago (31.5±3.31; 71.7±4.55; 1775.5±28.35; 258.21); Akra (4.1±1.13; 2.0±0.51; 81.6±6.39; 12.66); and Ekumpoano (27.2±5.8; 6.2±1.20; 69.7±8.12; 33.67) of the Central region exceeded the individual radioactivity levels of the Western region. Heavy minerals such as Zircon, Rutile and Amphibole were identified in the beach sands of the Central and Western regions. The minerals found are known to concentrate REEs and are indicative of shore-derived minerals. Rare earth elements were found in beach sands at both regions. Total Rare Earth Elements (TREEs) distribution in the beach sands of the Central region ranged as coarse fraction (6.33 to 13.30 ppm); medium fraction (8.56 to 53.15 ppm) and fine fraction (16.67 to 795.01 ppm). The sum of Light Rare Earth Elements (LREEs); Heavy Rare Earths (HREEs); and ratio of light to heavy rare earth (LREE/HREE) distribution in the Central region were: coarse fraction (5.56 to 11.77 ppm; 0.64 to 1.53 ppm; 5.81to 9.89); medium fraction (7.72 to 48.13 pm; 0.84 to 5.02 ppm; 5.83 to 9.95); and fine fraction (14.98 to 727 ppm; 1.69 to 74.53 ppm; 4.43 to 10.79). The TREE distribution in the beach sands of the Western region varies as follows; coarse (5.69 to 29.78 ppm); medium (9.51 to 85.58 ppm) and fine fraction (24.3 to 86.28). The sum of light LREEs, HREEs and ratio of light to heavy rare earth (LREE/HREE) distribution in the Western beach sands were: coarse fraction (5.07 to 26.08 ppm; 0.62 to 3.70 ppm; 6.67 to 10.11); medium fraction (8.47 to 76.8ppm; 1.04 to 8.78 ppm; 3.97 to 9.56) and fine fraction (21.6 to 77.46 ppm; 2.7 to 17.63 ppm; 2.76 to 8.78). Despite the prominence of REE- fingerprints in the beach sands of Dago, Akra and Ekumpoano in the Central region, the corresponding increase in radioactivity concentrations at these locations (Dago, Akra and Ekumpoano) suggest strong influence of the geology of these areas. The sharp decrease in the concentration of total REEs in the beach sands of Akra shows an anomaly despite the fact that the sampling points are along the same trend. The geospatial observation of the coastline along the Central region showed that the sampling location at Dago and Ekumpoano are on probable geological faults and have differing geology. The study has also revealed that the radioactivity distribution in the beach sands serves as pathfinders to potential rare earth elements deposits in the Central region. Although heavy REEs were found in relatively higher concentrations in the beach sands of the Western region, the REEs in the fine fractions of the Central region exceeded that of the Western region. Consequently, the renewable energy target which relies on selected rare earth elements is achievable if more resources are committed towards potential sources of the REEs in-land.Item Characterization of Atmospheric Particulate Matter at E-Waste Landfill Site in Agbogbloshie, Accra(University of Ghana, 2017-07) Ahiamadjie, H.A year-long investigation has been carried out on atmospheric particulate matter (APM). Elemental composition,mass concentration, sources contributions and their ngerprints were determined in APM samples collected, in Agbogbloshie scrap market, between May 2010 and April 2011. PM2:5 and PM102:5 size fractions of APM were collected 24-hourly on 47 mm diameter nuclepore lters of pore sizes 0.4 μm and 8 μm respectively, using the Gent sampler. Gravimetric analyses were carried out to determine the APM mass concentrations. The minimum, maximum and annual mean mass concentration values for PM2:5 obtained for the sampling site throughout the period of investigation were 35.43 ( g=cm3), 349.68 ( g=cm3) and 88.62 ( g=cm3) respectively. For PM10��2:5, the minimum, maximum and annual mean mass concentration values obtained were 76.83( g=cm3), 448.67 ( g=cm3) and 138.31 ( g=cm3) respectively. These measured concentration levels are all substantially higher than the WHO, USEPA, EU, JAPAN EQS, UK National Air quality objective, World Bank and Canada air quality standards. Particle Induced X-Ray Emmission (PIXE), Particle Induced Gamma Emmission (PIGE) and Energy Dispersive X-Ray Fluorescence (EDXRF) were used to determine elemental composition and concentration of the atmospheric particulate matter. The ve most abundant elements in coarse fraction PM102:5 are Si average 6545.05 (range: 261.3359950.56) ngm��3, Al average 3743.25 (range: 218.9424719.25) ngm��3, Fe average 12464.77 (range: 182.0818982.45) ngm��3 , Cl average 5918.47 (range: 587.76 15796.13) ngm��3, Na average 4040.17, (range: 418.2515010.32) ngm��3. In the ne fraction (PM2:5) concentrations reordered were in the following order: Si average 5466.44 (range: 1339.9361029.16) ngm��3 , Al average 3073.44 (range: 888.7425389.05) ngm��3, Fe average 1877.57 ( range : 769.2819569.65) ngm��3, Cl average 4972.86 (range: 1533.3616741.73) ngm��3, Na average 3163.27 (range: 1295.1515887.22) ngm��3. Enrichment Factor evaluation was rst used as one of the means to separate elements in terms of natural and anthropogenic sources. PMF was employed in ngerprint and source contributions identi cations, PMF resolved ve sources each for both PM2:5 and PM10��25. The following sources were identi ed for the PM2:5:E-waste burning (49%), Industrial activities (23%), vehicular tra c (16%), resuspended dust (7%) and sea spray (5%). In the coarse fraction, soil dust (45%),biomass burning (17%), Heavy oil burning (16%),sea spray (12%) and e-waste burning (10%) were apportioned. Natural sources (45%) were the major contributors in the coarse fraction while anthropogenic sources(88%) were the major contributors in the ne fraction. E-waste burning contributions were identied in both fractions. In this work, the following elements (Zn, As, Br, Sn, Cd, Hg, Pb) have been identi ed as ngerprint for e-waste burning and this source contributed 49% of the pollutants identied in the study area.Item Numerical Simulation of Dispersion of Emissions from Tema Oil Refinery in Ghana(University Of Ghana, 2015-07) Affum, H. A.; Affum, H.AThe petrochemical industry is a major contributor of industrial air pollutants which are known to have dire consequences on human health and the environment, neccesitating research into their dispersion and transport. The objective of the study, therefore, is to simulate the dispersion and transport of pollutants emitted during the processing of crude oil by the Tema Oil Refinery in the Greater Accra region of Ghana using the California Pu_ (CALPUFF) modeling system. This thesis couples the Weather Research and forecasting Model (WRF) with the non-steady state California Pu_(CALPUFF) modelling system to simulate the dispersion and transport of emissions from the refinery in a coastal urban/industrial area in Ghana. The mass balance approah was employed to estimate the refinery emission rates which were used as input for the dispersion model. Emission rates of five species were estimated - SO2, NO2, PM2:5, CO2 and VOCs. The transport and dispersion of SO2, NO2 and PM2:5 were modelled over the period between 2008 - 2013 and their impact on 38 identified receptors investigated. Simulation results showed that the radius of impact of the emissions is approximately 10 km. As a result of the prevailing predominant south-westerly winds in the study area, concentrations of emissions at receptors located upwind of the emission source were found to be higher as the winds carried the pollutant clouds in their direction. Conversely, south and south-western receptors, relative to the refinery, on the other hand, were minimally impacted. Concentrations of SO2 and NO2 at 2 out of the 38 receptors exceeded the regulatory limit of the World Health Organisation and Ghana's Environmental Protection Agency. It can be concluded, therefore, that SO2 and NO2 emissions from the refinery do not pose any danger to the larger population and the general environment nearby. PM2:5 levels at 36 receptors however exceeded the WHO guideline value leading to the conclusion that the refinery operations could pose some dangers to the environment regarding PM2:5. The dispersion model results were compared with measurements at the same location in order to validate the model. Similarly, observations from two meteorological stations were compared with results from the meteorological model. The performance evaluation, with the aid of statistical measures revealed that the models' performance were acceptable.Item Modelling Radionuclides Transport and Fate in Groundwater Systems: A Case Study of Newmont Akyem Goldmine in Ghana(University of Ghana, 2015-12) Adukpo, O.K.; Darko, E.O.; Fletcher, J.J.; University of Ghana, College of Basic and Applied Sciences School of Nuclear and Allied SciencesIt has been established that radionuclides accumulates during mining and mineral ore processing, leaching into water bodies and thus increases natu- rally occuring radioactive materials (NORM) concentration levels. In this work, theoretical and experimental methods have been used to study ra- dionuclides transport and fate in groundwater systems at the Newmont Akyem Goldmine in the Eastern Region of Ghana. Radiation doses from radionuclides in groundwater have been modeled by considering advection- di_usion equation in underground system. A mathematical model using a numerical solution based on the _nite di_erence method has been used to describe the transport processes of radionuclides in the groundwater systems under continuous distraction as a result of mining activities. A code written in Matlab was used to compute the numerical solutions of the advection-di_usion equations using available site speci_c parameters. The results of the model predict an increasing concentration of radionuclides of the U-Th Series and the potential radiation doses through consump- tion of groundwater in the study area. The solutions may prove useful for simpli_ed analysis of radionuclide transport in groundwater. Analyti- cal solution was used to verify the results from the numerical model with some experimental data obtained from gamma ray spectroscopy analysis. For experimental veri_cation two sampling zones were earmarked: within 5 kilometers radius and 10 kilometers radius from the mine concession. The average annual committed e_ective doses from theoretical and experimen- tal methods were 1.14 _Sv and 1.05 _Sv respectively. The trend of results of measurement from the gamma spectrometry analysis agreed with the model objective especially wells and boreholes that take their sources from the mine area.