A.A. Alabi, A.O. Adewale, J.O. Coker and O.A. Ogunkoya
Geophysical and geotechnical techniques were used to investigate the sub-surface information of a proposed site for a hostel construction at Federal University of Agriculture, Abeokuta. Ten vertical electrical sounding (VES) stations were adopted. Typical sounding curves obtained include the HA, KH, AKH and KQH types, of which the AKH-type consists of 40% of the survey points, and a maximum of five geo-electric sub-surface layers were delineated. Laboratory analyses were performed to investigate particle size distribution, Atterberg limit, compaction limit, California bearing ratio (CBR) and specific gravity. The CBR revealed that all soil samples, except L4, are mechanically stable and have high load-bearing capacity. The Atterberg limit test and the geo-electric section showed that the second layer of VES 4 is composed of sandy clay with high plastic index and low liquid limit, which may pose a threat to the foundation of any engineering structure. VES locations 5, 6 and 8 were identified as high groundwater potential zones suitable for optimum groundwater abstraction. The study area is suitable for both shallow and deep foundations, however VES 4 and VES 5 require reinforcement.
Aderemi A. Alabi, Johnson O. Aina, Adebambo O. Adewale and Abass A. Ajanaku
We assessed the effect of different land use types on the physical and chemical properties of soil. We analysed three cases. Nine soil samples were taken at different depths (0–10, 10–20 and 20–30 cm) from three locations, namely, sawmill, dumpsite and market. Analyses were carried out to determine the influences on the physical and chemical properties of the soil. All the land types had considerably high sand contents, with minor silt and clay. Available phosphorus and the exchangeable bases were significantly (p ≤ 0.05) affected by land use and soil depth. Moisture content (p ≤ 0.05) was significantly affected by land use, while bulk density (p ≤ 0.01) was significantly affected by soil depth. Soil organic matter and carbon were also generally low in all three locations. Consequently, ameliorative land management practices have to be adopted to prevent nutrient loss and land degradation.
A.A Alabi, V Makinde, A.O Adewale, J.O Coker and T.J Aluko
The aeromagnetic data of Idogo, Southwestern Nigeria, have been used to study the lithology and to determine the magnetic source parameters within Idogo and its environs. Idogo lies between latitudes 6°30′N and 7°00′N and between longitudes 2°30′E and 3°00′E. The magnetic anomaly map, the regional geology, the analytic signal and the local wavenumber were used to identify the nature and depth of the magnetic sources in the region. Data enhancement was carried out to delineate the residual features relative to the strong regional gradients and intense anomalies due to the basin features. The estimated basement depth using the horizontal gradient method revealed depths ranging between 0.55 km and 2.49 km, while the analytic signal amplitude and local wavenumber methods estimated depth to the magnetic sources to range from 0.57 km to 4.22 km and 0.96 km to 2.43 km, respectively. Depth computations suggested the presence of both shallow and deep sources. The total magnetic intensity values ranged from 3.1 nT to 108.3 nT. The area shows magnetic closures of various sizes in different parts of the area trending West, with prominence at the centre and distributed East–West.
B.O. Adetoye, A.B. Alabi, T. Akomolafe, P.B. Managutti, N. Coppede, M. Villani, D. Calestani, A. Zappetini and C. Maurizio
One-dimensional (1D) zinc oxide (ZnO) nanostructures (nanorods) were synthesized on a glass slide and fluorine-doped tin oxide (SnO2/F or FTO) coated glass (FTO/glass) by a wet chemical method. The structural, morphological and optical analyses of the as-deposited ZnO nanostructures were performed by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and UV-Vis spectroscopy, respectively. The XRD results showed that the nanostructures as-deposited on the glass and the FTO/glass substrates were of ZnO wurtzite crystal structure, and the crystallite sizes estimated from the (0 0 2) planes were 60.832 nm and 64.876 nm, respectively. The SEM images showed the growth of densely oriented ZnO nanorods with a hexagonal-faceted morphology. The UV-Vis absorption spectrum revealed high absorbance properties in the ultraviolet range and low absorbance properties in the visible range. The optical energy band gap of the ZnO nanostructure was estimated to be 3.87 eV by the absorption spectrum fitting (ASF) method.