Geochemical assessment of groundwater pollution from sewage effluents in the University Campus of Ibadan,southwestern Nigeria

Sewage effluent is often rich in toxic constituents leading to environmental hazard. Continuous discharge of sewage effluents into an agricultural training farm in University of Ibadan is polluting groundwater used for cultivation of vegetables and cereals, as also for drinking, thus posing risk to human health. The study area is underlain by Precambrian banded gneisses. The study is based on seven groundwater samples and twenty-three soil samples collected from seven trial pits. The samples have been analysed using AtomicAbsorption Spectrophotometric and Inductively Coupled Plasma- Emission Spectroscopy respectively.Water analyses data show that the concentrations of Fe, Pb and Cd have exceeded the WHO (2006) drinking-water quality guidelines. Correlation coefficient of water shows that the coefficient corresponding to zero has a percentage of 29, whereas 71 % of correlation is either from the same source or from different source of enrichment. The correlation analysis of soil samples shows that 92.9% of the elements have the same source. The enrichment factor and geo-accumulation analyses confirm enrichment of Cu, Cd, Fe, Pb, Zn, Sr, Ba, Mn, Ni and La concentrations contributing to the pollution. All the metals analysed in the soil sample from the farm have anthropogenic influence.     

Predicting moisture content of soil from thermal properties using artificial neural network

Monitoring of soil moisture contents is an important practice for irrigation water management. The benefit of periodic soil water content data includes improved irrigation scheduling in order to optimize water usage for improved crop productivity. However, the in situ equipment for measuring soil water contents have high maintenance and operation cost and are highly affected by neighboring soil conditions, and some have overwhelming calibration and data interpretation, whereas the common standard laboratory procedure requires much effort and can be time-consuming for large dataset. The objective of this study is to evaluate the applicability of artificial neural network (ANN) to predict moisture content of soil using available or measured thermal properties (thermal conductivity, thermal diffusivity, specific heat, and temperature) of soil. We used both multilayered perception (MLP) and radial basis function (RBF) types of ANN. The study area is a farmland situated within the premises of the University of Ibadan campus. Thermal properties were measured with KD2 Pro at 42 points along seven transects. Soil samples were also collected at these points to determine their moisture contents in the laboratory. ANN analysis carried out effectively predicted the soil moisture content with very low root-mean-square error (RMSE) and high correlation coefficient (R) of approximately 0.9 for the two methods evaluated. The overall results suggest that ANN can be incorporated to predict the moisture content of soil in this area where thermal properties are known.     

Hydrocarbon reservoir characterization of “AY” field,deep-water Niger Delta using 3D seismic and well logs

Three-dimensional seismic and well log data from nine wells were used for the characterization of “AY” field in the deep-water, Niger Delta. Result shows that the field has a complex structural arrangement consisting of series of northeast-southwest-trending and northwest-dipping synthetic faults. Petrophysical evaluation of the available well logs helped in identifying 11 hydrocarbon-bearing sands noted as A1000, A1100, A1200, A2000, B2000, B2100, C3000, C3100, D4000, D4100, and E5000. Reservoirs A1000, A1100, A1200, A2000, B2000, C3000, and D4000 are gas-bearing sands while reservoirs B2100, C3100, D4100, and E5000 are oil bearing. The average effective porosity of these reservoirs ranges from 0.168 to 0.292; water saturation is estimated to be between 0.177 and 0.59 and net-to-gross (NTG) ratio from 0.081 to 0.734. Considering the uncertainty in the input petrophysical parameters as well as structural uncertainty particularly in fluid contact, the total hydrocarbon reserves in the field were estimated to vary between 266.942 and 334.457 Bscf and 132.612 and 150.036 MMbbl for gas and oil volumes, respectively.     

The use of multivariate statistical analysis in the assessment of groundwater hydrochemistry in some parts of southwestern Nigeria

Arabian Journal of Geosciences - Turabah area is located in the southwestern Arabian Shield of Saudi Arabia. The present study aims to shed light on the origin and mechanism of formation of the...