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- ItemOpen AccessApplication of geoelectrical and chemical methods for groundwater assessment in Isheri-North, Ogun state, Nigeria(Journal of Science and Technology (Ghana), 2015) Adeoti, L; Bello, M.A; Olatinsu, O.B; Adiat, K.A.NGeoelectrical investigation and chemical analyses were carried out at Isheri North area of Ogun State in order to assess the groundwater quality at shallow depth and its deep potential zone for groundwater development. The study area has been selected for investigation due to infiltration of the polluted Ogun River. Forty-three (43) Schlumberger Vertical Electrical Soundings (VES) and chemical analyses of water samples from one hand dug well and two shallow boreholes in the study area were carried out. Four to five geoelectric layers which correspond to top soil, clayey sand, sandy clay, clay and sand were delineated. The longitudinal conductance values (0.02 - 0.106mhos) of the topsoil in the area reveal its poor to weak protective capacity, thus exposing the underlying clayey sand to contamination as reflected from its resistivity values ranging from 4.8-15.1Ωm. This low resistivity zone at shallow depth (3 – 26m), occasioned by infiltration, was further ascertained by high values of conductivity, turbidity, total hardness, TDS, Cl, Fe, and Mn ions in the analyzed water samples taken at depth ranges from 9 – 16m. The results of the analyzed water samples from this shallow zone are beyond international standards for drinking water. The underlying clay resistivity values ranged between 1.9 - 6.1Ωm and thickness varied from 50.8 - 100.5m. This acts as the seal for the underlying aquifer (sand layer). The resistivity of the sand layer varied from 91.7-159Ωm with a depth interval of 101.7-109.4m and 73.4-82.3m in VES 1 and VES 14 respectively. This constitutes the deep aquifer units in the study area. The longitudinal conductance values of the overburden above the profound aquifer units varied between 10.5-33.0 mhos and are indicative of very good to excellent protective capacity rating. Thus, the underlying deep aquifer units are well protected from being contaminated.
- ItemOpen AccessApplication of Geophysical and Geotechnical Methods to Site Characterization for Construction Purposes at Ikoyi, Lagos, Nigeria(Journal of Earth Sciences and Geotechnical Engineering, 2011) Oyedele, K.F; Oladele, S; Adedoyin, OAbstract An integrated geophysical and geotechnical survey was carried out in a proposed engineering site at Ikoyi, Lagos, Nigeria. The survey aimed to image shallow subsurface with a view to evaluate the stratigraphy and competency of the shallow formation as foundation materials. Geotechnical investigation involving Cone Penetration Testing (CPT) and Standard Penetration Testing (SPT) were carried out on the site. Geophysical technique involving Vertical Electrical Sounding (VES) was also implemented and the data were processed, inverted and interpreted. Geophysical and geotechnical tests showed good agreement. Four to five subsurface layers were delineated within the study area: the topsoil loose sand, peat/clay, sandy clay, sand and clay. This indicates good correlation with the soil layers in bore logs. The existence of loose sand, peat and clay near at the surface is capable of being inimical to building structures. The subsurface layers up to the depth of 16 m are mechanically unstable with low penetration resistance value which may not serve as good foundation materials. Shallow foundation is considered unsuitable for the intended building. In view of unsuitability of shallow foundation in this area, structures in this area should be safely founded in competent and mechanically stable coarse sand through pilling.
- ItemOpen AccessApplication of Three Electrical Resistivity Arrays to Evaluate Resolution Capacity of Fractured Zones at Apatara Farms, Iwo, Osun State, Nigeria(Journal of Applied Sciences and Environmental Management, 2017) Adeoti, L; Afolabi, O.S; Ojo, A; Ishola, S.KThe study applied three different electrical resistivity arrays (Wenner, dipole-dipole, and Pole-dipole) based on their resolution capacity to delineate fractured zones at Apatara Farm in Iwo, Osun State, Nigeria. Theoretical apparent resistivity data were computed for each model and contaminated with 5% Gaussian noise as a further concession to real field conditions. The simulated results revealed that the Wenner array gave the least error in trying to reconstruct the true model when the fractured zone is placed near the subsurface. However, when the fractured zone is placed at a depth beyond 5 m, the Dipole-Dipole array gave a better resolution than Pole-Dipole and Wenner array in decreasing order of resolution. The study further revealed that the Wenner array is less susceptible to edge effect at shallow depth while Dipole-dipole is more susceptible to edge effect at deeper depth followed by the Pole-dipole array. 2D electrical resistivity field measurements were carried out to confirm the results of the numerical simulation in the same field using the same parameters. The inverted resistivity images showed that the fractured zones are well delineated by the Dipole-dipole and Pole-dipole arrays but poorly resolved by the Wenner array. The study has demonstrated the usefulness of numerical modelling for imaging of fractured zone necessary for hydrogeological purpose and through modelling, the user has unlimited power to image or simulate a real-world scenario seamlessly before carrying out the actual field survey.
- ItemOpen AccessApplication of uphole seismic refraction survey for subsurface investigation: a case study of Liso Field, Niger Delta, Nigeria(World Applied Sciences Journal, 2013) Adeoti, L; Ishola, K.S; Adesanya, O; Olodu, U; Bello, M.AIn this paper, an uphole refraction survey was carried out at the location of LISO Field in Niger Delta Nigeria in order to determine/estimate the thickness and velocities of the strata with a view to ascertaining the suitability of these layers for seismic reflection data acquisition and engineering structures. A hole drilled to a depth below the weathered layer contained hydrophones positioned at specific depths and dynamite charge as source of seismic energy. The uphole data were acquired using OYO McSeis seismograph. The time- distance plot obtained using IXsexsegy software was used for picking the first breaks arrivals of the signals. The depth of the weathered layer was obtained from these plots. The upsphere software was used to obtain the velocity of the different layers. The cuttings collected during the borehole drilling reveal sand, clay and gravel in which the sand sequence vary in sizes. Analyses of well-log show that the area of study is a two-layer model and the near surface geology is comparatively stable and inhomogeneous with moderate velocity contrast. The average thickness of the weathered layer to the top of the consolidated layer is 4.8m with an average velocity of 466m/s. The weathering thickness ranges from 2.9-8.9m and the velocity ranging from 362m/s to 689m/s. The consolidated layer velocities ranges from 1642m/s to 1884m/s with an average of 1746m/s sufficient enough to support engineering structures. In order to correct for weathering or statics a datum of about 6m deep would be required as this will eliminate the effect of the weathered layer on any proposed engineering structure to be developed in the area or its environs. This will also be suitable for the acquisition of good quality seismic data in the area. Also, mathematical linear regression models were generated relating the velocities of the layers and depth of the weathered layer which could be used for the prediction of one parameter in the absence of others provided they are within the same geologic environment.
- ItemOpen AccessAssessment of groundwater prospect and aquifer protective capacity using resistivity method in Olabisi Onabanjo University campus, Ago-Iwoye, Southwestern Nigeria.(Elsevier, 2018) Bayewu, O. O; Oloruntola, M. O; Mosuro, Laniyan, T. A; G. O; Ariyo, S. O and Fatoba J. O.Electrical resistivity investigation was carried out at Olabisi Onabanjo University campus, Ago-Iwoye, Southwestern Nigeria with the aim of evaluating groundwater potential and aquifer protective capacity of the overburden units in the area. The underlain rocks are predominantly porphyroblastic and banded gneiss, quartz schist and biotite-hornblende granite. Twenty-Four Vertical Electrical Sounding (VES) were probed using Schlumberger array with maximum current electrode spacing (AB/2) of 100 m at each point using the OHMEGA Allied resistivity meter.The data were interpreted using the partial curve matching and computer iteration programme using WINRESIST. Parameters such as overburden thickness, basement resistivity, reflection coefficient and longitudinal conductance were calculated and used for evaluating the groundwater potential and aquifer vulnerability of the study area. Thepredominant VES curve types obtained are KH, H, A, AKH, HKH and HA. The geoelectric sections show that the area is underlain by 3–5 layers: the topsoil (72.4–1735.6Ωm), clay/clayey sand/sand/laterite (18.9–1349.5Ωm), fractured basement (430.7–1021.4Ωm) and the fresh basement (433.3–7146.4Ωm). The plotted isopach map showed an overburden thickness range of 4.9–28.2 m with values greater than 20 m at the south-eastern and south-western parts of area.The reflection coefficient range is between 0.62 and 0.98 while protective capacity range is between 0.03 and 0.28. Groundwater potential of the area were classified as high (overburden thickness > 13 m and reflection coefficient < 0.8);medium(overburden thickness > 13 m and reflection coefficient≥0.8); and low (overburden thickness < 13 m and reflection coefficient > 0.8). The protective capacity rating falls between poor to moderate, thus, vulnerable to infiltration of leachate and other surface contaminants. The study therefore helped in identifying favourable groundwater potential and the aquifer vulnerability of the area.
- ItemOpen AccessAssessment of heavy metal bioremediation potential of bacterial isolates from landfill soils(Elsevier, 2021) Oziegbe, O.; Oluduro, A. O.; Oziegbe, E. J.; Ahuekwe, E. F.; Olorunsola, S. J.
- ItemOpen AccessAssessment of Heavy Metals Leaching in Groundwater of Industrial Areas of Nigeria(2015) Ojekunle, Z.O.; Rasak, A.M.; Mustapha, D.Z.; Ojekunle, V.O.; Sangowusi, R.O.; Oyebanji, F.F.; Adekitan, A.A.; OdjegbaPollution of ground water with heavy metals from industrial activities has caused a major threat to human life exposing man to series of diseases, crippling disability and death. This study was carried out to determine the concentration of heavy metals leaching into groundwater from the industrial activities and to assess their long term effect on life of the people and the resultant aquifer. The study was carried out at 10 different locations which are all located in Ikeja industrial areas. The water samples collected were subjected to physical, chemical, heavy metal and bacteriological analysis in order to determine their level of pollution. Samples were prepared according to the standard methods using atomic absorption spectrophotometry for heavy metals determination. The result of the analysis shows that heavy metals in water samples had an average pH mean value of 5.20 indicating the acidity of the water sampled, while the average electrical conductivity, temperature and total acidity of were 0.64µs/cm 29.70 o C and 29.60 respectively. The average mean concentration of the chemical and heavy metals were 0.132 mg/l, 0.040 mg/l, 0.279 mg/l, 0.148 mg/l, 0.026 mg/l, 0.0055 mg/l, 0.00266 mg/l and 0.0097 mg/l for calcium, magnesium, sodium, potassium, iron, cadmium, lead, and chromium respectively. The parameters analysed were at varying concentrations in the groundwater with parameters such as nitrate, phosphate, and pH exceeding the World Health Organization (W.H.O) standard, it was observed that the sample collected from Neimeth pharmaceuticals exceeded the permissible level for iron and lead having the value of 0.0391mg/l and 0.0627mg/l, while most of the water samples analysed falls within the permissible limit in accordance with the WHO standards. Adequate care must be taken for further prevention and handling of chemical discharges from industries. The need for the treatment of the groundwater and control of human activities in the area to prevent further contamination must also be put be in place.
- ItemOpen AccessAssessment Of Potentially Toxic Elements (PTEs) in Soil Within Some Selected Automobile Workshops in Lagos, South West Nigeria(2019) Odukoya, A.M; Uruowhe, B.O; Dada, A.This study has evaluated the levels of selected Potentially Toxic Elements (PTES) in some mechanic workshops in Lagos Southwest Nigeria. Twenty-five top soil samples were collected and analysed for six PTEs using ICP-MS. The mean values of the PTEs decrease in the order of Zn >Pb> Cu > Ni > As > Cd and the ranges were as follows: Zn (178 - 1273 mglkg); Pb (52.3 - - Smz g); Cu (30.6 - 102 mglkg); Ni (12.5 - 51 mglkg); As (1.73 - 22.3 mg/kg) and Cd (0.45- _. - mglkg). The following indices of pollution and health risks were calculated: the pollution index (PI), pollution load index (PU), potential ecological risk index (PERI), hazard index (HI), on-carcinogenic risk and carcinogenic risk index. All the toxic elements were higher than crus tal a 'erage values except for Ni. Based on PU and PERI, the soil samples can be classified as erately polluted with Ni and highly polluted with Cu, Zn, As, Cd, andPb. The potential logical risk index (PERI) ranged between 171.55 - 1084.88 and indicated moderate to very .gh risk in the study area. The calculated Hazard Index (HI) for only ingestion and dermal ;' + -ays were >1 and posed non carcinogenic health risks to both children and adults. The ~ er risk values for Ni, As and Cd were within the acceptable benchmark of 1 in 10,000 (10-4) 1,000.000 (10-6) therefore posed no carcinogenic health risks in the study area. Some PTEs ~ ysed constituted high non carcinogenic risk in the study area with children athigher risk than . and Co, Pb and As from both the ingestion and dermal pathwaysare the major contributor e health risk.
- ItemOpen AccessAssessment of Potentially Toxic Elements Pollution and Human Health Risk in Soil of Ilesha Gold Mining Site, Southwest Nigeria.(Journal of the Geological Society of India, 2018) Odukoya, A.M; Olobaniyi, S.B; Oluseyi, T.OThe paper presents results of research to determine the health risk of potentially toxic elements (PTEs) in soils of gold mining area in Ilesha, Southwestern Nigeria. Eighteen top soil samples were collected and analysed for PTEs using ICPMS. The pollution level in soils were assessed using pollution load index (PLI) and potential ecological risk index (PERI). The human health risk was assessed using hazard index (HI), non-carcinogenic risk index and carcinogenic risk index. All the PTEs were higher than crustal average values except Fe and follow the order Mn > Ba > Cr > Zn > Cu > Ni > Pb > Co >Fe > As > Cd. The soil samples can be classified as unpolluted to moderately polluted (0.18-1.23) and low risk (15.28-94.24) based on PLI and PERI respectively. The values of hazard Index (HI) calculated for child and adult population for all the pathways were <1 and pose no obvious non carcinogenic risk to the population except for ingestion pathway where 33% of the samples showed value >1 in child population. As, Co, Cd and Pb constituted high cancer risk in the study area with child at higher risk than adult. The Total Cancer Risk (TCR) in the study area based on all the pathways ranges between 0.19 -3.86 and 0.18-3.58 for child and adult respectively and the ingestion route seems to be the major contributor to excess lifetime cancer risk followed by the dermal pathway.
- ItemOpen AccessBaseline evaluation of freshwater–saltwater interface in coastal aquifers of Badagry, south‑western Nigeria(Springer, 2019) Oloruntola, Moroof, Adetayo, Olateju, Ganiyu, Sadiq Folorunso, Bayewu Mosuro, AdewaleThis study focused on the evaluation of the baseline condition of saline water–groundwater interface in the coastal aquifers along Badagry, south-western Nigeria. Geologically, Badagry lies within the coastal sands and recent alluvium of the Dahomey Basin. Two-dimensional electrical resistivity tomography (2D-ERT) data along 15 survey lines were acquired in the study area, adopting the Wenner electrode arrays system with minimum spacing of 10 m. Ninety-one water samples were also collected, and their physical parameters were measured using hand-held devices. The (2D-ERT) data were processed and interpreted with the aid of DiProWin software. Sandy topmost layer, freshwater sand, brackish water sand and saline water sand were delineated from the study. Brackish water sand and freshwater sand layers were dominant in areas with high proximity to the Atlantic Ocean located in the south, which were not observed in the northern part of the mapped area. The study established the freshwater–saltwater interface at a depth of 10 m and above, in areas around the coast, while the interface occurs at depth greater than 50 m in areas 3–5 km from the coastal area. Observations from the pH and the TDS show that 87.3% of the samples are slightly acid, while less than 12.7% of them are slightly alkaline, while the TDS vary from 8 to 520 mg/l. The EC of the samples varies from 13 to 1140 µS/cm. All water samples are fresh groundwater, which confirms the occurrence of freshwater aquifer even in areas closer to the Atlantic Ocean.
- ItemOpen AccessBiogeochemical and engineering characteristics of soils and groundwater around a dumpsite(Earth Sciences Research Journal, 2013) Odukoya, A.M; Oresanya, O; Abimbola, A.FAn active dumpsite in Lagos south-western Nigeria was monitored to test natural attenuation efficiency in reducing contaminants by determining soil and groundwater biogeochemical and engineering properties within and around the site. From the Casagrande Plasticity Chart, the soil could be classified as clay or silt having intermediate to high plasticity; unsaturated zone thickness was 10-20m and permeability was low (1.96x10-5 to 41.8x10-5 m/s). Appropriate microorganisms, such as bacteria, viruses and fungi which are required for natural attenuation, were naturally present. Nutrients such as calcium, copper, magnesium, manganese, potassium, sodium and zinc, as well as electron donor (organic carbon) and electron acceptor (oxygen, nitrate, sulphate and iron), were also present in various amounts for effective natural attenuation. All the parameters analysed in water samples came within Environmental Protection Agency standards, except Fe, Na, Cl, NO3 , Al, Ba, Ni, total bacteria and total fungi. Phenol and total viral count were not detected in the two boreholes studied, but they showed values as high as 10,000 MPN/100ml and 230 CFU/100ml, respectively, in leachate. The concentration of contaminants in the soil was very high and inversely proportional to depth.
- ItemOpen AccessBiostratigraphy and Paleoecology of a Section of Shagamu Quarry (Southwestern Nigeria)(Pearl Research Journals, 2015) Ojekunle, V.O; Talabi, O.H; Ojekunle, Z.O.; Shanxiong, C.; Adewole, A.A.Twenty one representative samples collected from the quarry of West African Portland Cement Factory in Ogun State, 60km from Lagos state were treated for microfauna as well as studying the Lithological contents in other to establish the Biostratigraphy, Paleoecology and Lithology of the exposed strata. The treated microfauna content yielded Planktonic and Benthonic foraminifera along with Ostracods. These are studied to interpret the Biostratigraphy and Paleoecology of the study area. The Planktonic foraminifera species includes; Globorotalia aequa, Globorotalia acuta, Globorotalia pseudobulloides, Globigerina triculinoides. Benthonic foraminifera species includes; Bulimina asperoaculeata, Ammonia becarrii, Nonion costiferum, Bulimina paleocenica. The microfauna assemblages show diagnostic Paleocene to early Eocene age. This is established by the presence of Globigerina triculinoides and Globorotalia pseudobulloides as indicative of Paleocene to early Eocene trends. Paleontological deductions and reconstruction were made on the basis of foraminifera and ostracod assemblage. The combinations of Planktonic and Benthonic as well as the lithological characteristics of the study area reveals that the environment of deposition may be inner neritic with middle neritic influence due to partial exposure to the sea and these could be correlated with other areas in the world.
- ItemOpen AccessCHARACTERIZATION AND UTILIZATION OF CLAYS FROM ORIGO AND AWO SOUTHWESTERN NIGERIA(Zibeline International, 2019) Oziegbe, E. J.; Olarewaju, V. O.; Ocan, O. O.
- 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 AccessChemical composition of chromite and intergrown chlorite in metamorphosed ultramafic rocks (serpentinite and talc schist) of the Egbe-Isanlu schist belt, southwest Nigeria: genetic implications.(Journal of Mining and Geology, 2011) Olobaniyi, S.B; Mücke, AIn the Egbe-Isanlu schist belt serpentinite of dark and light greenish colours and whitish-grey talc schist occur. In these rocks black spots consisting of chromite are disseminated. Chromite is always intimately intergrown with chlorite . In serpentinite, chromite occurs first as compact and irregular crystals (up to 200 ìm) that may be associated with magnetite, ilmenite and sulphides or secondly as tiny crystals (5 ìm or smaller) which are concentrated within rectangular to rounded shaped outlines that represent the original shape of chromite grains. The latter type is predominantly developed in talc schist where tiny chromite crystals arranged in the herringbone structure are of subordinate abundance. The main end-members of the chromite solid solutions in serpentinite and talc schist are 2+ 3+ FeCr 0 (= chromite) and Fe Fe 0 (= magnetite) with the chromite-magnetite mole ratios generally higher in talc 2 4 2 4 schist than serpentinite. Chlorite has the composition of clinochlore and shows low level of chemical variability. However, Cr O and NiO occur in anomalously enhanced concentrations. Thermometric calculations suggest that 2 3 chlorite was formed or re-equilibrated within the greenschist metamorphic spectrum. This investigation revealed that, chromite originally contained in ultramafic rocks (= peridotite), inferred to be similar in composition to chromite of stratiform deposits, suffered chemical alterations during metamorphism. The original peridotite was transformed into serpentinite and talc schist while the altered chromite suffered a near complete loss of Al and Mg and the enrichment of Cr, Ti, Zn and Fe-concentrations.
- 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 AccessContamination assessment of surface and groundwater within and around two dumpsites(International Journal of Environmental Science & Technology, 2010) Odukoya, A.M; Abimbola, A.FGeochemical analyses of groundwater and streams flowing around abandoned and active dumpsites in Lagos, Southwestern Nigeria were carried out. Results show that water samples have generally low total dissolved solids with average values of 163.75 and 153.4 for abandoned and active dumpsites, respectively. pH ranges from 3.96- 8.34 while total hardness varies from 10-220 mg/L calcium carbonate (soft to slightly hard). Average concentrations of the dominant ions for abandoned and active dumpsites were 57.8 and 25.86 mg/L (Na) representing 40.7 and 46.3 % of the total cations respectively and Nitrate (av. 96.89 and 61.51 mg/L) representing 49.1 % and 40 %, respectively of the total anions. The pH, coliform count and concentrations of nitrate iron, manganese and sodium in most of the water samples were above the national drinking water standards proposed by the United States Environmental Protection Agency. Trace elements like silver, arsenic, beryllium, bismuth, cerium, cobalt, chromium, lithium selenium, tellurium, titanium, uranium, vanadium, tin and yttrium were below detection level for all the water samples while tungsten, thallium, molybdenum and lead were only present in surface and groundwater close to the dumpsites and also display values higher than recommended standards while cupper, zinc, aluminum, barium and strontium were present in most of the samples. The pollution index among all sites varied from 0.009 to 1.26 and 0.106 to 6.25 for abandoned and active dumpsites, respectively while the water around most of the dumpsite areas exceeded the acute and chronic effect levels proposed by the United States Environmental Protection Agency in 2007.
- ItemOpen AccessContamination Assessment of Toxic Elements in the Soil within and around two Dumpsites in Lagos, Nigeria.(Ife Journal of Science, 2015) Odukoya, A.MThis study assessed some contamination indices of trace elements in the soil within and around two dumpsites in Lagos, Southwestern Nigeria. This was with a view to assessing the degree of soil contamination. Thirty samples were collected from the two dumpsites, dried, disaggregated and sieved to <75um fraction for analysis of trace elements using aqua-regia digestion and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The soil generally showed background to minimum enrichment with arsenic, chromium, molybdenum and background to very high enrichment with cadmium, zinc, lead, Copper and nickel. Scandium, vanadium and strontium were only present in the active dumpsite with minimum enrichment while Lanthanum was present only in the abandoned dumpsite with background enrichment. The geo-accumulation index (Igeo) values for arsenic, chromium, molybdenum, manganese, lanthanum and arsenic, strontium, vanadium for active and abandoned dumpsites respectively were within background concentration. Chromium, scandium, molybdenum, nickel for active site and copper for the abandoned site fell in the class of moderate pollution. Cadmium, lead and zinc ranged between moderate pollution to strong pollution for the abandoned site while copper, cadmium, lead and i zinc fell within strong to extreme pollution for the active site. The grade of ecological risk indices (E ) for Chromium and Zn indicated low risk and low to moderate risk respectively for both dumpsites. Soil from the active dumpsite showed that arsenic fell within considerable risk, copper (moderate risk), lead and cadmium (very high risk). Soil from the abandoned dumpsite showed low to very high risk with copper, considerable to very high risk with arsenic, moderate to very high risk with lead and very high risk with cadmium. The potential ecological risk (RI) for the abandoned and the active dumpsites ranged between 43.86 to 1567.2 and 133.7 to 732.4 which indicated low to very high risk and very high risk respectively. The results of contamination degrees ranged between low and very high degree of contamination for both dumpsites.
- ItemOpen AccessDeformation Characteristics and Unloading Time for Passenger-Dedicated Railway Surcharge Preloaded Subgrade(Innovative Materials and Design for Sustainable Transportation Infrastructure, 2015-10) Ojekunle, V.O.; Shanxiong, C.; Yu, F.; Li, J.; Zhangjun, D.Analytical design of surcharge preloading schemes on soft soils were performed using the deformation characteristics corresponding to several surcharge preloading tests. To ascertain the reliability of this technique, investigative data were collected during the construction of a passenger dedicated railway line in China to deduce the design specifications and control standards. This was done by establishing an unloading time equation based on regression curve fitting method of the measured data; given that different types of settlement deformation gives corresponding unloading time calculations. Specific methods for the calculation of surcharge preloading and unloading time point for passengers dedicated line in the railway sector were also examined. Finally, measured data from the Wuhan-Guangzhou passenger line surcharge preloaded embankment were used to verify the design validity and reliability. The predicted results matched with the settlement deformation trend and the post-construction settlement strictly meet with the control standards.
- ItemOpen AccessDetermination of Ground Water Resources in Elekuro and Environs, Abeokuta(2015) Ojekunle, V.O.; Chen, S.; Ojekunle, M.O.; Oloruntola, M.O.; Li, J.Geophysical investigation of Elekuro and environs, Abeokuta, South western Nigeria was undertaken to explore the potential for further ground water development, considering the depth, thickness, resistivity and layer at which water can be obtained. The geo-electrical method used in the survey is Vertical Electrical Sounding. Six Vertical Electrical Soundings (VES) were conducted using the Schlumberger configuration covering the entire area. The VES data were subjected to an iteration software (WIN RESIST) which showed that the area is composed of top soil, weathered layer, fractured layer and basement. The result of a quantitative interpretation of the VES data obtained in a geophysical survey are represented by a geoelectric section which shows the sequence and relationship between the subsurface lithologies. The weathered layer and the fractured zone have been identified as the aquiferous in the area. The weathered layer is thicker in VES 1 and thinnest in VES 2, while the fracture basement is thickest in VES 1. Based on low resistivity values, overburden thickness and Reflection coefficient, VES1 has the highest and brightest potential for future groundwater exploration and development in addition to the existing ones.The study area falls within the basement complex of Southwestern Nigeria. The rocks are Precambrian in age as they lie between the pan African orogenic belts.