Moisture Sorption Characteristics of Dehydrated in-shell African Walnut (Tetracarpidium conophorum)

Moisture sorption isotherms are useful thermodynamic tools for determining water interactions within food systems and providing information that can assist in optimizing food processing operations such as drying, mixing, packaging and storage, as well as to maximize retention of quality parameters such as colour, aroma, texture, and nutrient. Moisture sorption isotherm characteristics of African walnut were evaluated at three different temperatures (28, 33 and 38°C) and relative humidity range of 11.20 - 97.00 % using gravimetric method; five mathematical models (GAB, BET, Peleg, Smith and Ferro Fontan) were fitted into the experimental data. Sorption isotherms of the dehydrated walnut gave type II (S-shaped) isotherms according to BET classification. Temperature had significant effect on the equilibrium moisture content (EMC). A nonlinear regression analysis method was used to evaluate the constants of sorption models. The models were evaluated statistically by calculating coefficient of determination (R2), the mean relative percentage error (P) and the reduced chi-square (λ2). The BET model gave the best fit for the obtained data among the tested models with R2 value of 0.9892. Calculated monolayer moisture (Mo) content from BET ranged from 5.018 to 7.922% db for adsorption and 9.842 to 10.143% db for desorption respectively

Soil Contamination and Risk Assessments on Selected Dumpsites within the Basement Complex and Sedimentary Formations of Ogun State, South-western Nigeria

The concentrations of inorganic elements in soils of Saje, Ita-Oshin, Premier, and Oke-Diya dumpsites were determined using an X-Ray Fluorescence spectrometer to assess the soil quality through chronological changes with depths. A soil core sampler collects 56 samples at 20, 40, 60, and 80 cm depths. Saje showed high mean concentrations of Ca, K, Fe, Rb, and Ti at all depths, while Oke-Diya revealed high mean concentrations of Ca, K, Fe, Rb, Ti, Mn, Zn, V, Cr, and Ni at all depths. These concentrations were in a closed range suggesting a build-up of elements in the soil profiles. Oke-Diya had the highest pollution index, followed by Saje, and the contaminations were from anthropogenic and geologic sources. The mean concentrations of Fe, Zn, Ni, Mn, Ti, K, and Ca were high at all depths in Ita-Oshin, and in Premier, the mean concentrations of K and Fe were high at all depths. Premier had the lowest pollution index. Ita-Oshin and Premier enrichment factors showed geologic sources. Saje and Oke-Diya revealed unacceptable non-carcinogenic risks for adults and children, and Ita-Oshin and Premier recorded acceptable limits. Saje and Oke-Diya samples had high carcinogenic risks for adults due to Cr, Pb, and As. Elements Cr and As in Ita-Oshin, and Pb in Premier evinced unacceptable carcinogenic risks for adults. Saje, Oke-Diya, and Premier indicated unacceptable carcinogenic risks for children due to Cr. The study showed toxins build-up in the soil system, and the study areas are not suitable for growing crops and sinking water wells for agricultural and domestic uses

Delineation of Leachate Plume Migration Using Electrical Resistivity Imaging on Lapite Dumpsite in Ibadan, Southwestern Nigeria

A geophysical investigation involving 2D resistivity survey was carried out on Lapite dump site that has been in operation since 1998 in ancient city of Ibadan, Southwestern Nigeria. The aim was to map the conductive leachate plume and extent of migration of leachate plumes in the subsurface for possible groundwater contamination. The 2D resistivity survey was carried out using Campus Tigre model resistivity meter with Wenner array configuration of electrode spacing distance ranging from 5 - 25m. A total of nine (9) 2D resistivity profiles with length ranging between 80 and 120 m were conducted within the dump site. A control profile of 2D resistivity survey was also carried out at about 300 m away from the dump site. The obtained resistivity data was interpreted using both RES2DINV and RES3DINV respectively. The 2D and 3D inverse resistivity models of the subsurface revealed the extent of leachate plumes with resistivity values less than 10 Ωm and allowed the location of leachate, clay soil, bedrock and seepage path from the dumpsite to be clearly delineated. There may be possible contamination of shallow groundwater system in the nearest future if proper mitigation measures are not taken into consideration at the dumpsit

Assessment of groundwater contamination around active dumpsite in Ibadan southwestern Nigeria using integrated electrical resistivity and hydrochemical methods

Investigation of groundwater contamination due to leachate migration in a solid waste disposal site was done using both geophysical and hydrochemical methods. The main goals were to delineate groundwater contamination due to leachate percolation and thus assessment of quality of groundwater from nearby hand-dug wells bordering the dumpsite for drinking purpose. A total of ten resistivity traverses were acquired within and outside the dumpsite using Wenner configuration with constant electrode separation ranging from 5 to 25 m. The 2D resistivity data were processed and inverted using RES2DINV and RES3DINV softwares, respectively. Geochemical assessment of groundwater samples were carried out according to APHA standards while hydrochemical facies of the sampled groundwater was evaluated using Piper Trilinear software. The inverse resistivity models of the subsurface from 2D and 3D imaging revealed low resistivity value less than 10 X m suspected to be leachate while 3D inverse sections allowed delineation of leachate, weathered layer, bedrock and seepage path from the dumpsite. The extent of migration was more pronounced in the southern part of the dumpsite, hence possible contamination of shallow groundwater system as dumpsite ages. The results of physico-chemical analyses showed the groundwater samples to be within the limits of WHO/NSDWQ for drinking purpose. However, higher values of concentrations of most analyzed parameters were noticed in well 1 due to its nearness to dumpsite and well 10 due to agricultural activities, respectively. Interpretation of Piper diagram showed CaHCO3 to be dominant facie in the area while alkaline earth metals (Ca2þ; Mg2þ) and weak acids (HCO3 -, CO3-) are dominant cations and anions during both climatic seasons. Groundwater in the study area is of hard, fresh and alkaline in natur

Investigation of Sub Soil Corrosion Using Electrical Resistivity Method: Federal University Oye Ekiti Phase II Campus as a case study

Electrical Resistivity survey was carried out with the aim of identifying the degree of soil corrosion associated with the sub soil of the Federal University Oye Ekiti phase II. The sub soil resistivity of the area was surveyed and evaluated using Ohmega resistivity meter. The sub soil resistivity parameters were used to delineate the degree of the sub soil corrosion. Four electrodes were inserted into the soil/rock using the Wenner profiling, vertical electrical sounding and Dipole- Dipole array along the traverses with a spacing of 5m and n =1 to 5.In this method, artificially generated electric current(I) was injected into the ground via two current electrodes while the resulting potential difference (V) is measured by another pair of electrodes. The survey revealed that the Southwest and Northwest regions of the study area were associated with high resistivity (200-500 Ω-m).This implies that the soil structure of the region is not corrosive, while the southeast region was associated with low resistivity (20-80 Ω-m) value which implies that the sub soil structure is corrosive. The degree of corrosion increases from the western to eastern part of the study area which may be due to bedrock topography. Of all the layers investigated, the topsoil layer is highly corrosive compare to other layers

Ground Magnetic Attributes For Subsurface Structural Analysis of Foundation Beds in a Sedimentary Terrain in Southwestern Nigeria: OSUSTECH Permanent Site as a case study

The structural failure such as subsidence, collapse and cracking of the walls of buildings in Nigeria has posed a threat or a significant potential hazard to the community in the affected areas. These hazards include gross loss of valuable lives and properties that always accompany such structural failure. Therefore there is need for subsurface structural analysis. The Stop-And-Go method was used for the acquisition of the data. This method is good for subsurface investigation at depths below 30 metres (100 feet). Data for this study were taken at a 10 metres station spacing which is about half that of the expected depth of target. The method requires the technique of measuring total field components at discrete points along the traverses distributed regularly throughout the survey area of interest. The raw data were processed to remove diurnal variations from the total field data measured from the base station. Interpretation of the ground magnetic data revealed that the study area comprises zones underlain with thin to thick overburden. In all the profiles, the regions A and B are associated with the high magnetic values except in the profile 4 in which only region E is associated with high magnetic values. Thus, the region E in the profile 4; the regions A and B in the profiles 1, 2, 3 and 5 are competent zones for the sitting of structures. It can be deduced that the regions of high magnetic susceptibility and high resistivity are competent zones for construction of high rise buildings and other engineering structures. While the regions of low magnetic susceptibility and low resistivity could pose problem of subsidence of the buildings around the region

Effect of Magnesium Addition on the Cell Structure of Foams Produced From Re-melted Aluminum Alloy Scrap

Closed-cell foams were produced from re-melted aluminum alloy scrap that contained 0.13 wt pct Mg magnesium in the as-received state and higher levels after adding 1, 2, or 5 wt pct Mg. The excess Mg gave rise to the fragmentation of long oxide filaments present in the scrap alloy into smaller filaments and improved its distribution and wetting by the Al matrix. Foaming the re-melted scrap alloy containing 1, 2, and 5 wt pct Mg excess showed stability and good expansion in comparison to the scrap alloy containing 0.13 wt pct Mg only, but the cells became non-equiaxed when the Mg concentration was high (≥2 wt pct excess) due to cell wall rupture during solidification. Compressibility and energy absorption behavior were studied for scrap alloy foams containing 1 wt pct Mg excess, which is the optimum level to obtain good expansion, stability, and uniform cell size. Foams with densities in the range of 0.2 to 0.4 g cm−1 produced by holding at the foaming temperature for different times were used for the investigation. A uniform cell structure led to flatter stress plateaus, higher energy absorption efficiencies, and reduced “knockdown” in strength compared with commercial foams made by gas bubbling. The mechanical performance found is comparable to that of commercial foams made by a similar method but the expected costs are lower

Evaluation of seasonal variation of water quality using multivariate statistical analysis and irrigation parameter indices in Ajakanga area, Ibadan, Nigeria

Abstract The variation of groundwater quality across different regions is of great importance in the study of groundwater so as to ascertain the sources of contaminants to available water sources. Geochemical assessment of groundwater samples from hand-dug wells were done within the vicinity of Ajakanga dumpsite, Ibadan, Southwestern, Nigeria, with the aim of assessing their suitability for domestic and irrigation purposes. Ten groundwater samples were collected both in dry and wet seasons for analysis of physicochemical parameters such as: pH, EC, TDS, Na+, K+, Ca2+, Mg2+, $$\text{HCO}_{3}^{ - }$$ HCO3- Cl−, $$\text{SO}_{4}^{2 - }$$ SO42- , $$\text{NO}_{3}^{2 - }$$ NO32- principal component analysis (PCA) and cluster analysis (CA) were used to determine probable sources of groundwater contamination. The results of the analyses showed the groundwater samples to be within permissible limits of WHO/NSDWQ, while elevated values of concentrations of most analyzed chemical constituents in water samples were noticed in S1 and S10 due to their nearness to the dumpsite and agricultural overflow, respectively. Groundwater in the study area is of hard, fresh and alkaline nature. There are very strong associations between EC and TDS, $$\text{HCO}_{3}^{ - }$$ HCO3- and $$\text{CO}_{3}^{2 - }$$ CO32- in both seasons. PCA identified five and three major factors accounting for 95.7 and 88.7% of total variation in water quality for dry and wet seasons, respectively. PCA also identified factors influencing water quality as those probably related to mineral dissolution, groundwater–rock interaction, weathering process and anthropogenic activities from the dumpsite. Results of CA show groups based on similar water quality characteristics and on the extent of proximity to the dumpsite. Assessment for irrigation purpose showed that most of the water samples were suitable for agricultural purpose except in a few locations

EVALUATION OF GROUNDWATER POTENTIAL OF ODEDA LOCAL GOVERNMENT AREA, OGUN STATE, SOUTHWEST NIGERIA

Evaluation of groundwater potential in Odeda Local Government Area, Ogun State, Southwestern Nigeria, has been carried out in this study using Vertical Electrical Sounding method. The study area is underlain by Precambrian Basement Complex rocks of Southwestern Nigeria. These rocks are inher-ently characterized by low porosity and permeability. The interpretation of thirty (30) vertical electrical sounding (VES) conducted using the Schlumberger electrode array shows four geo-electric layers in the subsurface within the study area. The overburden thickness varies from 5.9 to 39 m across the study area. This was used to prepare the groundwater potential map which assisted in the zoning of the area into low, medium and high groundwater potential zones. The study showed that about 60% of the study area falls within the low/medium rated groundwater potential zone while the remaining 40% constituted the high groundwater potential zone. Hence, the groundwater potential rating of the area is generally low

Groundwater Assessment of Hand Dug Wells around Open Landfill in Ibadan Metropolis for Domestic and Irrigation Purposes

Geochemical assessment of groundwater samples from hand-dug wells within the vicinity of Aba-Eku dumpsite was carried out for domestic and irrigation purposes. Ten groundwater samples were collected both in dry season and wet season for analysis of physico-chemical parameters: pH