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- ItemOpen AccessFacies analysis of the Bida sandstone formation around Kajita, Nupe Basin, Nigeria.(Journal of African Earth Sciences, 1996) Olaniyan, O; Olobaniyi, S.BA cluster analysis program was performed on a fifty by six data matrix derived from a granulometric study of the Bida Sandstone Formation around Kajita, Nigeria. Six lithofacies were derived from extraction of clusters. These are conglomerates, coarse pebbly sandstones, pebbly sandstones, coarse-grained, medium-grained and fine-grained sandstones. The seventh facies, claystones, was characterised only on the basis of field observations because it was too fine for sieving. The facies occur in a succession of multistorey fining upwards sequences whose cyclothems are truncated in places. Each cyclothem represents coarse traction deposits in channels, and fine deposits in overbank areas respectively. They are interpreted as deposits of braided ephemeral streams.
- ItemOpen AccessSilicate facies iron-formation of the Egbe-lsanlu Palaeoproterozoic schist belt, southwest Nigeria(Journal of African Earth Sciences, 1997) ANNOR, A.E; Olobaniyi, S.B; MUCKE, AField, petrological, mineralogical and geochemical data on the Egbe-lsanlu Palaeoproterozoic schist belt are presented, high-lighting the main features of a silicate facies iron-formation, which hitherto had been described as a metamorphosed, impure sandstone. The iron-formation is relatively thin (max. 15 m) and concordantly interbedded with schistose, semi-pelitic, amphibolitic and talcose host rocks, with which it shares a common polyphase tectonometamorphic history. The last of these is the Pan-African overprint, during which time the iron-formation was locally silicified. The main constituent minerals are garnet (almandine-spessartine solid solution), amphibole (Mn and Ca bearing grunerite-cummingtonite solid solution), quartz and ilmenite. Magnetite was not observed. Geochemical data show that the iron-formation and metasediments are of different origins. The silicate facies iron-formation of lsanlu belongs to the Algoma-type and was derived by the metamorphism of a volcano-exhalative-sedimentary protolith, probably during Eburnian times.
- ItemOpen AccessGeochemical characterization of soils, sediments and waters around active and abandoned dumpsites in Lagos.(Chinese Journal of Geochemistry, 2006) Abimbola, A.F; Odukoya, A.MIn developing countries, large amounts of wastes are dumped daily in open dumping sites without proper management. This practice usually causes enhanced concentration of metallic ions in environmental media within and beyond the vicinity of such dumps with attendant adverse environmental and health risks. Hence the aim of this study is to assess and elucidate the physico- and metallic ions concentrations in three environmental media (soils, sediments and waters) around active (Ojota) and abandoned (Isolo) dumpsites in Lagos and also to do a comparative study with reference to possible environmental and health impacts. A total of eighty samples comprising water, sediments and topsoils were collected around the two dumpsites. The soil and sediment were dried, disaggregated and sieved to <75 ~tm fraction for analysis of the metallic ions using aqua-regia digestion technique and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The analysis of metallic ions and cations in water was carded out using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) while unacidified water samples were analyzed for anions concentrations using the DIONEX DX-120 Ion Chromatography techniques. Analytical results show that pH, NO3, Fe, Mn and Na in most of the water samples are above WHO and EPA standards. Also there are relatively strong correlations between NO3 and C1, SO4, Coliform, TDS and EC which are an indicator of water contamination especially in the direction of groundwater flow. The mean values of the significant metallic ions present in the water samples include Cu (16.29 and 38.0), Zn (535.71 and 667.0), A1 (0.27 and 0.19), Ba (42.86 and 55.0), Sr (80.0 and 136.0) and B (118.7 and 160.2) for active (Ojota) and abandoned (Isolo) dumpsites respectively. Soil samples revealed varied concentrations with the estimated average contamination factors of 3.86 and 5.71 (As), 1.60 and 1.93 (Mo), 3.41 and 4.24 (Zn), 0.93 and 2.23 (Cu), 7.71 and 12.64 (Pb), 8.71 and 9.21(Cd) for both active and abandoned sites respectively. All these metals with Ag are also significant and follow the same trend in the sediments. Ag, Bi, Sb, Ga, Sc, M_n, Ga and La in soil samples are only significant for samples close to the dumpsites while Bi, Be, Sb, Co, Cu, La and Cr are significant for sediments taken downstream. Most of the metallic ions show significant enrichment in both soil and sediments while A1, B, Ba and Sr are only significant in water. These may be attributed to the adsorption characteristics of the soil and sediments, and relatively high mobility and solubility of the metals in water, respectively. The overall contamination degrees for both active and abandoned dumpsites are 23 and 34 for water, 40 and 30 for soil, 62 and 25 for sediments, respectively, which indicate a very high degree of contamination and a considerable degree of contamination, respectively. It can be concluded that samples around the abandoned dumpsite show higher level of contamination than those of active dumpsite. This may be the result of total decomposition and chemical reactions of wastes within the abandoned dumpsite as a result of its abandonment for a long time without any treatment measure, thus resulting in leachates plume that migrated from the dumpsite to the soil, surface water, sediments and eventually to the groundwater within and beyond the vicinity of the dnmpsite.
- ItemOpen AccessCharacterization by factor analysis of the chemical facies of groundwater in the deltaic plain sands aquifer of Warri, western Niger delta, Nigeria(African Journal of Science and Technology, 2006) Olobaniyi, S.B; Owoyemi, F.BThis paper examines the hydrochemical facies of groundwater present in the Deltaic Plain Sands aquifer of Warri and its immediate environs, maps their areal distribution and attempts to explain the controlling processes responsible for the various facies. 60 water samples were collected from wells tapping the Deltaic Plain Sands aquifer of Warri and environs and analyzed for various parameters including pH, total dissolved solids (TDS), K, Na, Ca, Mg, Cl, HCO3 and SO4 after standard procedures. The data obtained were subjected to R-mode factor analysis. Three factors were extracted. Factor 1 includes K, Na, Cl, and EC and reflects the signature of saline water incursion resulting from seepages into the aquifer of water from the tide-influenced River Warri. Factor 2 has high loading values of Mg, Ca, HCO3 and pH and represents the processes of natural rainwater recharge and water-soil/rock interaction. Factor 3 includes SO4 and can be related to the dissolution of sulphides from interstratified peat within the geological formation, heavy vehicular activity and the petroleum refining process in the town. The areal distributions of the various factor scores indicate that factors 1 and 2 are enhanced close to the banks of River Warri and decreases away from them. A broad zone of groundwater interaction (mixing) between water species represented by factors 1 and 2 is thus created towards the riverbanks. The implication of this is that ionic concentration in the water decreases away from the banks of the river an indication that the quality of groundwater improves away from the river. Factor 3 is enhanced in the southeastern portion of the town where it is deemed to be caused by the dissolution by groundwater of sulphur bearing minerals within the geological formaton, and also in the central and northwestern portions of the town were it could be related to the rain-dissolution of sulphur bearing compounds from gaseous emanations arising from vehicles and the petroleum refining process respectively, which eventually as acid-rain recharges aquifers in the vicinity. This paper demonstrates the effectiveness of factor analysis in evaluating hydrochemical processes in coastal and industrial areas
- ItemOpen AccessHydrogeochemical and bacteriological investigation of groundwater in Agbor area, southern Nigeria(Journal of Mining and Geology, 2007) Olobaniyi, S.B; OGALA, J.E; NFOR, N.BAgbor, a town in southwestern Nigeria, is underlain by the Miocene to Recent Benin Formation. Groundwater occurrence within the formation has been investigated for its quality, from which inferences are drawn on its usability and the prevalent hydrogeochemical processes in the water systems. The results indicate a chemical attribute of low pH, low total dissolved solids (TDS) and salinity. Cationic concentrations including Na+, K+, Ca2+, Mg2+ have values ranging from 0.9 to 18.9 mg/l, 0.1 to 4.2 mg/l, 1.2 to 12.8 mg/l and 0.2 to 3.5 mg/l respectively. Concentration values of Fe2+, Zn2+, Mn2+ and Pb2+ range from 0.08 to 1.92mg/l, 0.12 to 4.35 mg/l, 0.0 to 0.42 mg/l and 0.0 to 0.04 mg/l respectively. Anions including HCO3-, CO3, Cl, SO4, NO3, PO4 have respective concentration values ranging from 1.0 to 10.0 mg/l, 0.1 to 0.9 mg/l, 3.2 to 24.0mg/l, 0.0 to 10.3 mg/l, 0.0 to 18.4 mg/l and 0.0 to 2.4 mg/l. The bacteriological constituents of the water samples include Total aerobic bacteria counts (5 - 535cfu/ml) and Total coliform (10 - 70MPN/100ml). A comparison of these results with various quality guidelines, suggests that the groundwater may be suitable in its untreated state for crop irrigation, but will require pH remediation and microbial disinfection to upgrade its quality for potability and use in food processing industries. Factor analysis reveals three main hydrogeochemical activities operative within the groundwater system. Factor 1 is dominant and can be related to water-soil interaction and incorporation of leached formation water along the groundwater flow path. Factor 2 is related to pollution by biochemical related substances resulting from agricultural practices in the area. Factor 3 indicates fresh groundwater recharge. An inter-play of these processes, and base exchange reactions produced dominant chloride water types (Ca-Cl, Ca-Mg-Cl, Mg-Ca-Cl, Na-Ca-Cl and NaCl), and localized occurrences of bicarbonate types (NaHCO3 and Na-Ca-HCO3 .
- ItemOpen AccessPhysical and Sanitary Quality of Hand-Dug Well Water from Oil-Producing Area of Nigeria(Environmental monitoring and assessment, 2007) Ejechi, B.O; Olobaniyi, S.B; Ogban, F.E; Ugbe, F.CThe physical ( pH, Dissolved Solids, Dissolved Oxygen, conductivity, water depth temperature) and bacteriological (Total coliforms, Faecal coliforms) characteristics of 22 hand-dug wells in oil-rich Niger Delta of Nigeria were investigated. All coliforms counts (Log10 MPN/100 ml) varied from well to well ranging from 0 to 6.0 although faecal coliform counts were markedly lower (0–3.5 vs 1.0 – 6.0). When both seasons were compared, faecal coliform counts were significantly higher (t test; P < 0.05) during the wet season whereas no significant difference was observed in respect of total coliforms. Unlike the total coliforms, faecal coliform counts increased in wells close to septic tanks during the wet season. Although a declining trend was observed during the wet season, the values of the physical parameters were within WHO limits. The pH was slightly acidic (Mean ± SD: dry season, 6.04 ± 0.66; wet, 6.43 ± 0.62) and may be attributed to emissions from gas flaring and petroleum refining activities, which is common in the area. While the total coliform counts reflected the unsanitary habits of the well users, the detection of faecal coliforms exceeding recommended numbers in 63% of the wells render them unfit for domestic use. The public health implication is obvious considering the increasing number of people using the wells due to the rapid urbanization of the oilrich region.
- ItemOpen AccessInvestigation of the hydrological quality of Ethiope River watershed, Southern Nigeria.(Journal of Applied Sciences and Environmental Management, 2007) Omo-Irabor, O.O; Olobaniyi, S.BThe surface and groundwater resources of the Ethiope river watershed have been investigated for its hydrological and quality characteristics. The results indicate that Ethiope River is perennial and fed by groundwater seepages, precipitation and surface run-off from adjacent areas. The lowest discharge rate of the river is recorded in June and increases steadily reaching its peak in October. The physico-chemical parameters of both water sources include, pH (5.28-7.06), turbidity (1.16 – 8.12 NTU), conductivity (65.00- 127.0 µs/cm), dissolved oxygen (4.40-7.60 mg/l) and total hardness (25.50 – 45.0 mg/l). Others include, Na+ (3.91 – 27.05 mg/l), K+ (3.91 – 8.73 mg/l), Ca2+ (3.21 – 9.60 mg/l), Mg2+ (1.46- 5.84 mg/l), HCO3 - (31.50-80.00 mg/l), Cl (17.55 –35.10 mg/l), SO4 2- (0.25-0.58 mg/l), NO3 2- (0.19-0.55 mg/l) and PO4 2- (0.20-19.00 mg/l). This physico-chemical quality is generally compatible with WHO guideline for domestic use. Nevertheless, the water samples consist of high microbial population including total coliform bacteria counts (39.00 – 1100 MPN/100ml) and Escherichia coli (21.00 – 305.00 MPN/100ml), which render both surface and groundwater unfit for domestic use without disinfection. An assessment of surface water-groundwater homogeneity using the parametric student’s t and F tests on selected constituents (chloride, nitrate, sulphate, phosphate, sodium, potassium, calcium and magnesium), indicate non-significance in the variation within the tested parameters except for nitrate. This suggests some groundwater-surface water intermixing or communication, and the activity of denitrifying bacteria in surface water. A groundwater pollution vulnerability assessment using DRASTIC model indicates moderately high pollution risk level for the aquifer system.
- ItemOpen AccessExtent and distribution of groundwater resources in parts of Anambra State, Southeastern, Nigeria.(Journal of Applied Sciences and Environmental Management, 2007) Nfor, B.N; Olobaniyi, S.B; Ogala, J.EThe extent and distribution of groundwater resources in parts of Anambra State, Nigeria has been investigated. The results show that the study area is directly underlain by four different geological formations including, Alluvial Plain Sands, Ogwashi-Asaba Formation, Ameki/Nanka Sands and Imo Shale, with varying water storage and yielding capacities. Borehole depths within the Alluvial Plain Sands are shallow (5-30m) yet the sands are excellent aquifers with high yields (3-5 litres/sec) especially along the Anambra West – Onitsha - Ogbaru L.G.A. axis. Elsewhere the yield is low (about 0.5litres/sec) and may dry up at peak dry season periods. The Ogwashi-Asaba Formation occurs in a north-southerly trend and underlies Ekwusigo, Nnewi North and South and Ihiala Local Government Areas. This formation consists of multiple aquifers and a depth to water table ranging from 50 to 110m. Within it, transmissivity values of 37.54 to 95.5m2 /day and a yield of up to 5litres/sec were recorded. The Ameki/Nanka Sands is a prolific water producer and underlies Aguata, Anaocha, Njikoka, Dunukofia, Oyi and Anambra East Local Government Areas. Four aquifer horizons were identified within this formation, designated; shallow, upper, middle and deep aquifers. The most exploited are the upper and middle aquifers, while the least, but most prolific is the deep aquifer with an average yield of 5litres/sec. Imo Shale, because of its sedimentological nature is a poor aquifer. The gravelly intercalations within this formation are usually too thin to sustain continuous water pumping. This study indicates that the extent and distribution of groundwater within the study area is controlled predominantly by lithology and other secondary factors including topography and nearness to source of recharge.
- ItemOpen Accesscomparative study of cement and lime stabilization on geotechnical properties of lateritic soils derived from pegmatite in Ago-Iwoye area, southwestern Nigeria.(NMGS, 2008) Oloruntola, M. O; Adeyemi, G. O and Oduneye, O. C.Samples of pegmatite-derived lateritic soil around Ago-Iwoye, southwestern Nigeria, were differently stabilized with varying quantities of lime and cement. This was aimed at establishing the influence of types and quantities of the stabilizers, if any, on the geotechnical properties of the soil. The plasticity, moisture-density relationship, CBR and unconfined compressive strength of the unstabilized samples and those that were stabilized with 2, 4, 6, 8, and 10% by weight of cement and lime respectively were studied. Stabilization of the studied soil with between 2 and 10% cement produced percentage increase of 7.26%, 97.38%, 31.15% and 68.18% iin the maximum dry density (MDD), unsoaked California bearing ratio (CBR), soaked CBR, cured unconfined compressive strength and uncured unconfined respectively. Percentage reduction of 13.40%, 58.20%, 59.90%, 66.67%, 75.71%, 21.27% and 40.79% were obtained respectively in the MDD, cured and uncured compressive strengths, linear shrinkage, plasticity index, plastic limit and liquid limit of the samples stabilized with between 2 and 10% of lime. While addition of cement improved all the geotechnical properties, addition of lime reduced the MDD, uncured and cured unconfined compressive strengths. The investigation has thus confirmed that cement is more appropriate than lime in the stabilization of the studied soil, with optimum amount of stabilizer needed being 8%
- ItemOpen AccessSurface and groundwater water quality assessment using multivariate analytical methods: a case study of the Western Niger Delta, Nigeria(Physics and Chemistry of the Earth, 2008) Omo-Irabor, O.O; Olobaniyi, S.B; Oduyemi, K; Akunna, JThis study investigates the natural and anthropogenic processes that influence the chemistry of surface and groundwater within the western Niger Delta region using multivariate statistical techniques. A total of 137 surface and groundwater samples were collected between 2003 and 2007 during the rainy and dry seasons, from 15 sites and analysed for their physico-chemical constituents. The chemical data set generated were subjected to Principal Component Analysis (PCA)/Factor Analysis (FA) and Hierarchic Cluster Analysis (HCA). PCA is a procedure for reducing data redundancy, while FA establishes the general relationship among variables. CA is used to detect spatial similarity among sampling sites. The results indicate five dominant processes or factors for surface water that explained 77.11% of the variance in the data set. In groundwater, the factors account for 80.55% of the total variance. Cluster analysis revealed a random spatial distribution of the chemical components investigated. This is consistent with the multipurpose nature of land use in the study area. The multiple natural and anthropogenic sources indicated by this study, and their unsystematic distribution show that proper land use planning and firm implementation of existing environmental laws is imperative in this oil producing region, in order to have effective surface water and groundwater resource management.
- ItemOpen AccessAn integrated approach to volume of shale analysis: Niger Delta example, Offrire Field(World Applied Sciences Journal, 2009) Adeoti, L; Ayolabi, E.A; James, P.LAn integrated approach for the estimation of volume of shale from a suite of logs comprising the gamma ray, neutron-density combination, resistivity, combination of different methods (total) was carried in an Old Niger Delta Field called Orire with a view to ascertaining the reservoir quality and mapping reservoir bodies for further petrophysical analysis. The volume of shale (Vsh) calculation based on naturally occurring gamma ray frequently overestimates shale volume when encounters radioactive sand as sand appears shaly. In this situation, a Vsh calculation from neutron-density data yields a more accurate shale volume but in the presence of gas or light hydrocarbon, this approach is less accurate. The deficiency in this method is now addressed by Vsh calculation from the resistivity data. To avoid overestimation or underestimation of shale volume from any of the methods, the three methods were integrated to obtain Vsh total which finds the minimum value of all the methods. This approach distinguishes properly permeable bed (sand) from non-permeable bed (shale). Also from this method, the depositional environment was easily inferred.
- ItemOpen AccessEngineering geophysical approach to progressive or sudden collapse of engineering structures in Lagos, Nigeria.(The Journal of American Science, 2009) Oyedele, K.FEvery cubic meter removed during excavation, every unusual loading applied to a natural foundation bed, every pile driven into the ground, every construction operation in which the existing condition of the earth’s crust is affected is associated with geological features of some kind. Preliminary investigations of the relevant subsurface geology should therefore be of considerable value not only to the resident engineer on construction work but also to the contactor who is undertaking the work. The subsurface engineering geophysical information available at the beginning of a job can be fully effective information during the construction operation as well as post construction works. This paper presents the need for engineering geophysical survey in engineering site characterization.
- ItemOpen AccessGeophysical and hydrogeological evaluation of rising groundwater level in the coastal areas of Lagos, Nigeria(Bulletin of engineering geology and the environment, 2009) Oyedele, K.F; Ayolabi, E.A; Adeoti, L; Adegbola, R.BThe paper reports the change in groundwater level observed in 30 wells in ten locations in southern Nigeria. Borehole data confirmed the electrical resistivity soundings which indicated the presence of topsoil, medium sand, sand, clayey sand and coarse sand. In some cases, there was little apparent change in the rate of groundwater rise, but from the data obtained it can be concluded that in the years 2000–2004 the average yearly rise was 0.3 m while between 2004 and 2007 it rose on average by 0.5 m. This rise in groundwater level has serious implications for both existing structures and the nature of the foundations for future building. The electrical resistivity survey was found to be a helpful tool in detailing the morphology of the groundwater surface and is recommended for ongoing monitoring.
- ItemOpen AccessTotal Dissolved Solids (TDS) mapping in groundwater using geophysical method.(New York Science Journal, 2009) Oyedele, K.FThe reliability of electrical resistivity measurements to delineate subsurface total dissolved solid (TDS) in groundwater in Lagos, Nigeria, has been examined. Data from parametric resistivity soundings were correlated with laboratory measurements to provide information on the degree of total salinity of each aquiferous unit, depths to iso-conductivity surfaces and the various usage to which the groundwater from the studied area can be put to. The study revealed that TDS contrasts inferred from resistivity data can be used for effective monitoring and economic evaluation of groundwater salination.
- ItemOpen AccessEvaluation of Sea water Intrusion in Freshwater Aquifers in a Lagoon Coast: A Case Study of the University of Lagos Lagoon, Akoka, Nigeria.(New York Science Journal, 2009) Oyedele, K.F; Momoh, E.IABSTRACT: A geophysical technique has been employed to investigate seawater intrusion into freshwater aquifers in the coastal environment of the Lagos lagoon at the University of Lagos campus, Akoka, south-western Nigeria. Electrical resistivity method employing the Schlumberger array was used to acquire data for six vertical electrical soundings to investigate the vertical extent of seawater intrusion. The study revealed that the subsurface in contact with the lagoon was invaded by saline oceanic seawater. The Schlumberger electrode array which utilized current electrode half spacing from 1m to 500m was used to acquire both resistivity and induced polarization data in the proximity of the Lagos lagoon. Typical curve types reported for coastal areas such as the KQ, KQQ, and HKQ were observed in the investigated area and 4-6 geoelectric layers were delineated at an average depth of 71m. The subsurface lithology comprised of fine through medium grained sand to coarse sand intercalated in most cases with sandy clay and clayey sand. The resistivity of the intruded saline water was found to range between 1.8-37.2Ωm at a depth interval of 0.7-79m and the thickness of saline layers was found to be greater in the proximity of the coastline. The result of the investigation revealed that even under non-pumping conditions, the study area suffers from acute saline water intrusion and could be aggravated if there is groundwater abstraction. Ways to check the seawater intrusion problem through artificial recharge have been proposed in the study.
- ItemOpen AccessSeismic refraction and resistivity studies of part of Igbogbo township, south-west Nigeria(Journal of Scientific Research and Development, 2009) Ayolabi, E.A; Adeoti, L; Oshinlaja, N.A; Adeosun, I.O; Idowu, O.ISeismic refraction shooting and Electrical resistivity depth sounding have been carried out at Igbogbo (Ikorodu area, Southwest Nigeria) to determine the structural setting of the subsurface materials and groundwater potential. A total of eighteen vertical electrical sounding using the schlumberger array of 500m maximum spread and twenty-seven seismic refraction data using forward and reverse shooting methods of lateral distance 42m along each profile were acquired within the study area. The results indicate the presence of three seismic refraction layers with the first layer having velocity 150-366m/s and thickness 1.0-3.3m, representing topsoil. The second refraction layer is composed of lateritic clay with thickness 4.5-10.5m and velocity 578-878m/s. The third refraction layer consists of sandy clay with velocity 1000- 2500m/s. The delineated refraction layers are characterized by increase in velocity with depth. The geoelectric sounding clearly show that the subsurface layers are characterized by topsoil, laterite, sandy clay, clayey sand, sand and clay with sand acting as aquifer units. The two thick aquifer units mapped are capable of sustainable industrial development in the area. The seismic refraction shooting was able to delineate three layers because of the energy source used which is consistent with the first three layers in geoelectric sounding. To attain deeper depths of penetration using seismic refraction method, a stronger energy source is recommended.
- ItemOpen AccessHydrogeochemical Study, Health Implications and Interpretation of Surface Water Analysis Around Rural Settlements of Ita sin and Oki-gbode, Southwestern, Nigeria.(Journal of Appli ed Sciences Research, 2010) Ikhane, P.R; Folorunso, A.F; Shonibare, O.L; Odukoya, A.M; Shomoye, C.OA total of twelve water sa mples were collected from two rivers in ltasin and Oki-Gbode nreas of lmobi, southwestern Nigeria, six (6) from each river and analyzed for chemical and physical quality parameters. The two water bodies serve the inhabilcHltS of these communities as source of drinking water, agricultural and domestic uses. The hydrochemical parameters deterlllinecl include major cntions and ani0ns using Induct ively Coupled Plnsrna Optical Emission Spectroscopy (ICI'-OES) and the ion Chromnlogrnphy methods to evaluate the water type, qunlity and usnge. The physicnl analysis of the water samples were determined and the resu lts indicate that the pl-1 and Total Dissolved Solids (TDS) values nmge from 4.4-5.5 and 2 1.00- 75.00 mg/L respectively, Electrica l Conductance (EC) ranges from 32.3 1- 1 15.39 mS/cm and Sodium Adsorption Ratio (SAR) from 1.62-3.39. Results of the chemical and physical analysis obtained for the ri ver water samples were assessed and compared with World Health Organizntion (W II O) and Standard Organization of Nigeria (SON) stan dards in order to deduce if the water satisfies all the· conditions for potability, irrigation and industrial use in low pressure boilers. 'Results obtained show that the Weller samples do not fit for drinking from the two standards c.mployed, but C
- ItemOpen AccessTechnical feasibility of direct application of the Nigerian tar sand deposits as road asphalt.(Pacific Journal of Science and Technology, 2010) Akinmosin, A; Shoyemi, A.OTar sand samples were collected at five locations in parts of Southwestern Nigeria, and were analyzed to determine their direct application as road asphalt surfacing material. Seven samples were selected out fifteen samples collected in the field for this analysis using the Marshall test method. The test involved determination of bitumen saturation, stability, flow, density, specific gravity, etc. on the samples. The stability values ranged from 14.0% to 40.0%; density ranged from 1.70kg/m3 to 1.92kg/m3 , and general specific gravity values of 1.01 and 1.92 were obtained for the bitumen and mixed aggregate, respectively. The Marshall test result indicates that two out of the seven samples (AG20 and AG8) can be applied directly, having flow values of 13mm and 15mm, respectively, and with a reasonably high bitumen saturation (>30%). Other samples with low stability and low bitumen saturation (<30%) require further analysis on Design Mix which was carried out in order to increase their stability. This involved the addition of certain materials like coarse aggregate and fillers to increase the stability and wearing course of the samples. Result of the Design Mix showed increase in specific gravity, density and stability values that are favorable for direct application.
- ItemOpen AccessGeophysical investigation of saline water intrusion into freshwater aquifers: A case study of Oniru, Lagos State(Scientific Research and Essays, 2010) Adeoti, L; Alile, O.M; Uchegbulam, OA total of five electrical imaging lines were measured using the wenner configuration. And a total of twelve VES was carried out within the area of investigation. The lines were aligned almost in a linearly NS azimuths, perpendicular to the ocean. The results were presented as profiles, multi-profiles, maps, pseudo sections and inverted sections. Interpretations of these results involve both qualitative and quantitative deductions from 1D and 2D geoelectric models. WingLink software was utilized for plotting, filtering, modeling and iterations of the resistivity data. From the quantitative interpretation and nearby well log data five distinct layers were identified. The layers are dry and unconsolidated sand, clayey sand, saline sand, saline clay and freshwater sand. The resistivity of the topsoil varies from 3259.59 Ohm-m on VES 2 - 67.04 Ohm-m on VES 12. The resistivity of the freshwater sand varies from 1649.76 Ohm-m on VES 6 - 158.28 Ohm-m on VES 10. The resistivity of the saline layer (saline sand/clay) varies from 2.06 Ohm-m on VES 12 - 39.88 Ohm-m on VES 3. The depth to saline/freshwater interface varies from 12.97 m on VES 8 - 63.01 m on VES 5. The quality of groundwater varies from poor polluted saline water saturated sand/clay through intermediate water quality clayey sand/sand to freshwater sand. The interpreted results show saline water plumes where they occur in different part of the area investigated. The 1D and 2D results correlate to a very high degree indicating saline water intrusion between depth interval of 13 and 64 m in the study area. Two major freshwater aquifers (shallow < 6 m and deep > 60 m) where delineated with most of them occurring unprotected. The results showed the effectiveness and usefulness of electrical resistivity and induced polarization method in mapping saline water intrusion problem in coastal areas.
- ItemOpen AccessSite Investigations of Subsurface Conditions Using Electrical Resistivity Method and Cone Penetration Test at Medina Estate, Gbagada, Lagos, Nigeria(World Applied Sciences Journal, 2010) Oyedele, K.F; Olorode, D.OSeveral buildings at Medina Estate, Gbagada, Lagos State, have undergone differential settlement of various degrees. An investigation was therefore carried out to unravel the prevalent subsurface geological conditions. 1D and 2D resistivity measurements alongside cone penetration tests were carried out within the undeveloped part of the estate. The results of the tests showed the site to be underlaid by various shades of clay occurring from existing ground to over 20m in many parts of the site. Sands of appreciable thickness were found to occur at depth range of 14 to over 25m in some parts of the site. The information obtained showed that the soil at shallow depths consists of an extensive layer of material of extremely low shear strength and a corresponding high volume of compressibility potential, thus making shallow foundation impossible except some form of soil improvement.