Geo-electrical investigation of Leachate Impact on Groundwater: A Case Study of Ile- Epo Dumpsite, Lagos, Nigeria

In the past few decades, disposal sites have been filled with household refuse and different kinds of potentially dangerous industrial waste in an uncontrolled manner which poses an enormous risk for the environment, and are the main sources for groundwater contamination. With the aim of assessing impact of leachate on the underlying aquifers by determining and delineating possible leachate infiltration into the aquifer matrix ,Constant Spacing Traversing (CST) was carried out using Wenner array and spacing between 10-60 m along four 160 m – 180 m profiles. The results revealed the aquifer is characterized by low resistivity response generally below 4.5 ohm-m depicting possible contamination of the underlying aquifer from Oke-Odo landfill. The surface of the waste landfill is characterized by differential decomposition of waste as zones of advanced decomposition and fresh waste are reflected as low and high resistivity respectively. The absence of leachate in the aquifer 100 m from the studied area suggests that the leachate has not spread to this area, therefore, safe for groundwater exploitation. This study demonstrated the expeditiousness and effectiveness of the resistivity technique as a tool for geo-environmental mapping of leachat

Ex Ante Economic Impact of Genetically Modified (GM) Cowpea in Benin

The net impact of pest-resistant GM crops on the welfare of both producers and consumers in developing countries is currently unknown and subject to speculation. This study uses choice-based conjoint protocol to estimate the net impact of pest-resistant Genetically Modified (GM) cowpea on net social welfare in Benin given price and income risks. Results imply that Bt cowpea will increase expected net social welfare by about $US 50 million per year in Benin given no inefficiencies in the seed sector. If inefficiencies in the seed sector are such that cowpea growers can access Bt cowpea seeds only 50$US 11 million per year.Crop Production/Industries,

Application of geoelectrical and chemical methods for groundwater assessment in Isheri-North, Ogun state, Nigeria

Geoelectrical 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 4.8-15.1m. 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 - 6.1m 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 91.7-159m 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.Keywords: Electrical Resistivity, Groundwater, Aquifer, Geoelectric Sectio

Integrated approach for groundwater assessment in Yetunde Brown, Ifako, Gbagada, Lagos State, Nigeria

The poor quality of potable water sourced from boreholes and hand dug wells at Yetunde Brown, Gbagada, Lagos informed the integration of geophysical, physicochemical and Water Quality Index (WQI) to assess the condition of groundwater in the study area. Twenty-Five (25) Vertical Electrical Sounding (VES) data were acquired and complemented with water samples collected from three boreholes and two hand-dug wells within the neighborhood of the study area. The VES data were partially curve matched and inverted. Physicochemical parameters were measured in water samples. The results of the VES data revealed four to five geo-electric layers which correspond to the topsoil (with layer thickness and resistivity values from 0.6 to 1.3 m and 20.1 to 361.4 Ωm respectively), clay (with layer thickness and resistivity of 1.7 to 5.2 m and 2.8 to 22.1 Ωm), sandy clay (with layer thickness and resistivity values of 2.8 to 5.9 m and 12.4 to 56.8 Ωm) and clayey sand (with layer thickness and resistivity values of 23.8 to 31.8 m and 7.2 to 94.2 Ωm). The sand in VES 7, 9, 12-18 and 20 has resistivity values ranging from 151 to 331.5 Ωm. The depth to the identified aquifers fluctuates between 23.8 and 90.4 m. The measured iron, chloride and lead ions are above World Health Organization (WHO) recommendation for potable water in some water samples. WQI calculated reflected poor quality for two boreholes only, which could be due to the unconfined aquifers delineated in the second and fourth geo-electric layers making the water vulnerable to contamination. The study recommended that bore hole should be sunk at VES 7, 9, 12, 13, 18 and 20 at depth between 31.8 to 66.6 m for exploitation of good quality water.Keywords: Groundwater, Electrical resistivity, Water quality index, physicochemical analysis, Aquife

Reservoir fluid determination from angle stacked seismic volumes in ‘Jay’ field, Niger Delta, Nigeria

The study was carried out to investigate the dissimilar seismic amplitude responses observed in sandstone reservoirs with the same fluid saturation. This challenge now informed the analysis of different amplitude responses from the ‘Jay’ Field in order to verify the reservoirs fluids around and away from well location based on the integration of Amplitude Variation with Angle (AVA) and seismic inversions. The well log data provided were used to identify hydrocarbon bearing zones and Poisson Ratio analysis. Anomalies from the AVA analysis were investigated using the elastic impedance inversion of the near and far volumes. Crossplots of Lambda-Mu-Rho inversion were produced to relate reservoir incompressibility and rigidity modulus for lithology and fluid determination. Sand E exhibited amplitude increase with angles at well point and also away from well location (red triangle). The approximate elastic impedances of the inverted seismics are almost similar to the log estimates, an indication of good correlation. Integration of incompressibility (Lambda-Rho) and rigidity (Mu-Rho) modulus analyses reveals the presence of gas saturation in reservoir Sand G because low Lambda-Rho coincides with high Mu-Rho from both log estimates and inverted seismics. In the case of Sand D, high Lambda-Rho coincides with high Mu-Rho because it is oil saturated. This study has helped to differentiate the fluids in Sands D and G despite having similar AVA responses. The methods adopted in this work can be useful in hydrocarbon detection from seismic data in fields with similar geological setting.Keywords: Amplitude Variation with Angles; Elastic Impedance; Near and Far offsets; Full stack seismic volum

Geo-electrical investigation of Leachate Impact on Groundwater: A Case Study of Ile- Epo Dumpsite, Lagos, Nigeria

In the past few decades, disposal sites have been filled with household refuse and different kinds of potentially dangerous industrial waste in an uncontrolled manner which poses an enormous risk for the environment, and are the main sources for groundwater contamination. With the aim of assessing impact of leachate on the underlying aquifers by determining and delineating possible leachate infiltration into the aquifer matrix ,Constant Spacing Traversing (CST) was carried out using Wenner array and spacing between 10-60 m along four 160 m \u2013 180 m profiles. The results revealed the aquifer is characterized by low resistivity response generally below 4.5 ohm-m depicting possible contamination of the underlying aquifer from Oke-Odo landfill. The surface of the waste landfill is characterized by differential decomposition of waste as zones of advanced decomposition and fresh waste are reflected as low and high resistivity respectively. The absence of leachate in the aquifer 100 m from the studied area suggests that the leachate has not spread to this area, therefore, safe for groundwater exploitation. This study demonstrated the expeditiousness and effectiveness of the resistivity technique as a tool for geo-environmental mapping of leachate

Mineral analysis reveals extreme manganese concentrations in wild harvested and commercially available edible termites

Termites are widely used as a food resource, particularly in Africa and Asia. Markets for insects as food are also expanding worldwide. To inform the development of insect-based foods, we analysed selected minerals (Fe-Mn-Zn-Cu-Mg) in wild-harvested and commercially available termites. Mineral values were compared to selected commercially available insects. Alate termites, of the genera Macrotermes and Odontotermes, showed remarkably high manganese (Mn) content (292-515mg/100gdw), roughly 50-100 times the concentrations detected in other insects. Other mineral elements occur at moderate concentrations in all insects examined. On further examination, the Mn is located primarily in the abdomens of the Macrotermes subhyalinus; with scanning electron microscopy revealing small spherical structures highly enriched for Mn. We identify the fungus comb, of Macrotermes subhyanus, as a potential biological source of the high Mn concentrations. Consuming even small quantities of termite alates could exceed current upper recommended intakes for Mn in both adults and children. Given the widespread use of termites as food, a better understanding the sources, distribution and bio-availability of these high Mn concentrations in termite alates is needed

Variability in traditional processing of gari: a major food security product from cassava

Cassava is a major crop for food security in Nigeria and its principal processed form is gari. Gari processing practices were observed in the southwest (Oyo State) and southeast (Benue State) of Nigeria using two complementary approaches: 1) semi-quantitative surveys with processors (n=123) and 2) actual detailed measurements at processing units (n=7). Size of processing operations and type of practices differed significantly between the two States. There were also intra-State differences, influenced by ethnicity and customs. Variability of processing practices should be considered whilst seeking to improve processing productivity and introducing nutritious varieties of cassava to feed fast-growing Nigerian population

Geo-electrical investigation of Leachate Impact on Groundwater: A Case Study of Ile- Epo Dumpsite, Lagos, Nigeria

In the past few decades, disposal sites have been filled with household refuse and different kinds of potentially dangerous industrial waste in an uncontrolled manner which poses an enormous risk for the environment, and are the main sources for groundwater contamination. With the aim of assessing impact of leachate on the underlying aquifers by determining and delineating possible leachate infiltration into the aquifer matrix ,Constant Spacing Traversing (CST) was carried out using Wenner array and spacing between 10-60 m along four 160 m – 180 m profiles. The results revealed the aquifer is characterized by low resistivity response generally below 4.5 ohm-m depicting possible contamination of the underlying aquifer from Oke-Odo landfill. The surface of the waste landfill is characterized by differential decomposition of waste as zones of advanced decomposition and fresh waste are reflected as low and high resistivity respectively. The absence of leachate in the aquifer 100 m from the studied area suggests that the leachate has not spread to this area, therefore, safe for groundwater exploitation. This study demonstrated the expeditiousness and effectiveness of the resistivity technique as a tool for geo-environmental mapping of leachat