A Comparative Study of Down - Deep Hydrophone Seismic Refraction Survey and Drill Logs for the Determination of Near Surface Layer Velocity and Thickness Over ‘Galos’ Field, Niger Delta, Nigeria

Uphole acquisition was conducted to determine the weathering thickness and velocity of strata layer, in essence obtain values for static correction to be used in the processing of reflection data. Drill logs from each Uphole point was used in conjunction with the theoretical interpretations as a physical set of data to aid in making inferences for boundary distinction. Fifty two (52) Uphole locations were drilled and logged. Each location was drilled to 66m and logged to 60m. Litho logy from the bore samples reveals dominantly sand and clay units. The sand sizes ranges from fine to coarse.The records / playbacks have good signal quality with distinct first break times. The UDISYS interpretation software guided by surface (shot depth) correction and shot offset correction displayed a two-layered case. Analysis on the weathering thickness and velocities within the prospect area reveals that uphole locations have weathering thickness ranging from 2.7m to 11.0m. The highest velocity within the weathering layer is 924m/s (254m/s to 924) while the velocity of the consolidated layer ranges from 1528ms to 1927ms. Appreciably, this correlates with the formation samples collected at various uphole lithology logs. More so, it is of interest to note that low velocity layer / weathering thickness within the prospect area synchronized with previous study of the Niger Delta weathering velocity layer. Keywords: Drill-hole, down-deep, Critical angle, Near surface, weathering layer

Contamination assessment of dumpsites in Ughelli, Nigeria using the Leachate Pollution Index method

The leachate pollution index (LPI) technique has been used to quantify pollution potential in Ughelli, Nigeria. Water samples were collected from boreholes around four dumpsites for laboratory analysis and estimation of their LPI. The values were found to be 11.95, 11.32, 8.47 and 10.08, for Omotor Dumpsite (OD), Iwhreko Dumpsite (ID), Divine Dumpsite (DD) and Ughelli Market Dumpsite (UMD) respectively. These values are higher than the standard of 7.378. Therefore, Leachate characterization and the LPI values revealed that the groundwater in the area has been impacted due to leachate percolation. It is recommended that remediation procedures should be put in place as soon as possible for better water quality in the area.Keywords: Pollution index; remediation; biodegradation; water quality; hydrogeochemical analysis, pollutant variable

Delineation of Groundwater Contamination Using Self Potential Method in Effurun, Delta State, Nigeria

Spontaneous Potential profiling has been carried out around a dumpsite in Effurun near Warri, Delta State, Nigeria. This is with a bid to determine qualitatively the presence of contaminant in the groundwater around the area due to electrochemical and electrokinetic processes arising from arbitrary disposal of both domestic and industrial waste. The study was carried out by engaging two different electrode configurations, which include the gradient and the fixed base arrays. This is to reduce or eliminate cumulative errors and electro - telluric noise connected with variations in the earth's magnetic field and other cultural sources. The data acquisition was carried out along the two orthogonal traverse lines. Electrode spacing of 5 m and 10 m in both techniques were adopted. Also, the data was acquired during the raining and dry season, to determine the effect of climatic changes on leachate generation and migration. The profiles generated show high positive potential of up to 70 mV outside the dumpsite area to as low as -60 mV around the dumpsite area using the gradient array, and 120 mV to -30 mV using the fixed base array in both the raining and dry seasons. This low and negative potential readings around the dumpsite area could be the confirmation of the redox activities taking place at depth, and contaminating the aquifer and groundwater.Keywords: electrokinetic, electrochemical, contaminant, self potential, electrode

Evaluation of the protection and hydraulic characteristics of the aquifer formation using second order geoelectric indices and pumping test in Aghalokpe, Nigeria

In this work, the vertical electrical sounding method and the borehole pumping test analysis were used to investigate the study area and to assess the geoelectrohydraulic parameters and aquifer protective capacity. Fifteen (15) Vertical electrical sounding (VES) stations spread across the study area with a maximum electrode separation, AB/2 of 200 m were occupied. The results provide information on aquifer electrical and hydraulic properties which included the aquifer resistivity, aquifer thickness and depth, longitudinal unit conductance, transverse resistance, hydraulic conductivity and transmissivity. The aquifer resistivity values ranged from 503–18914 Ωm, with a depth for adequate water production given as 14 m to a maximum of 22 m. The calculated longitudinal conductance and inferred protective capacity ranged from 0.0141 - 0.167 mho, indicating weak to moderate capacity. The borehole pumping test data was analysed using the Cooper-Jacob method in determining the aquifer parameters. The hydraulic conductivity (K) value mea sured from a reference well was combined with DarZarrouk parameters to estimate the transmissivity and hydraulic conductivity values of the aquifer across the area. The results showed that the aquifer transmissivity values varied from 198.8 m2/day to 1473.6 m2/day with an average of 459.8 m2/day, while hydraulic conductivity values varied from 5.7 m/day to 66.7 m/day, with an average of 31.1 m/day. These estimated parameters indicate that even though the area has high aquifer potential due to its transmissivity and hydraulic conductivity values, it is prone to contamination due to its poor protective capacity. Keywords: Geoelectric indices, Aghalokpe, Aquifer parameters, Pumping test, Dar- Zarrou

Tooth shade presentations at a University Teaching Hospital

Aim: To determine common tooth shades among randomly selected subjects in our hospital.Background: Dento-facial aesthetics is a subject of concern to everyone. Disharmony in colour between natural and prosthetic teeth is a common cause of dissatisfaction with prosthetic rehabilitation. The pattern of tooth shade presentation in our centre is yet to be reported.Materials and Methods: This comparative observational study was conducted in a tertiary hospital among 300 randomly selected adult subjects  who had full complement of upper anterior teeth. Vita Classic shade guide was employed for the study. To prevent bias, the identification codes on the shade tabs were blinded. An upper left central incisor was employed as the index tooth. Standard principles for tooth shades selection were followed. The shade tab that matched or close to the index tooth was selected for every individual. Age and gender of the subjects were recorded.Chi Sq statistical test was performed to determine the relationship between gender and tooth shades. The level of significance was set at p ≤ 0.05.Results: Most of the subjects were females, 162 (54.0%) and the age range was18-75yrs. The commonest tooth shade among the subjects was Vita Classic A2 (15.7%) followed by A1 (12.7%) and A3 (10.3%). No case of D1 (0%) was seen and only 2 cases (0.7%) of C4 were encountered. Overall, shade A was the most frequently encountered Hue, 142 (47.3%) followed by shade B, 71 (23.7%). Shade C was the least encountered Hue, 36 (12.0%). There was no statistically significant relationship between gender and shade(χ²=12.799,P=0.618).Conclusion: The commonest tooth shade among the subjects was Vita Classic A2 and the least was D1. Shade A was the most frequently  encountered Hue. Keyword: aesthetics, shade guide, tooth shad

Descriptive analysis for physico-chemical parameters of leachate and groundwater resistivity in the sedimentary basin, Southern Nigeria: A case study

Geostatistical analysis has been applied in the investigation of groundwater contamination in three dumpsites and a Control site in Warri and its environs in Southern Nigeria. This was to map the impact of contaminant emanating from indiscriminate dumping of domestic and industrial wastes on groundwater in the area. Sixteen (16) VES stations were occupied in the three dumpsites and the control site studied using the Schlumberger configuration. From each of the site, water samples were collected from boreholes, hand dug wells, and swamps, close to VES stations for chemical analysis and statistical evaluation using multiple regression analysis and Two - way Analysis of Variance (ANOVA). Aquifer resistivity ranges from 15 Ωm to 215 Ωm in the dumpsites area, and 336 to 884 Ωm in the control site. Hydro-geochemical analysis of water samples showed values of parameters that are higher around the dumpsites when compared to the control site, with the results for conductivity, nitrates, iron, lead and total viable bacteria count exceeding the standard permissible limits. A correlation of aquifer resistivity and hydro-geochemical analysis parameters show that resistivity of groundwater is significantly related to its physico-chemical properties with a contribution of 49.2 %. Also, at the significant level, P<0.05, the contribution, R2 value (0.513) show that 51.3% of the presence of Total Viable Bacteria Count is attributed to groundwater resistivity in Warri and its environs.Keyword: Multiple regressions, Bacteria count, Leachate, Sounding curve, Permissible Limi

Lithological Identification and Underground Water Conditions in Jeddo Using Geophysical and Geochemical Methods

Resistivity soundings and hydrogeochemical methods were carried out in order to establish the characteristics of the aquifer in Jeddo, Southern Nigeria. Results of the resistivity sounding revealed that the formation is made up of clay, clayey sand, and fine- to coarse-grained sand. The mean depth of the aquifer was obtained as 12.7 m while the aquifer resistivity ranged from 161 to 1728 Ωm. The mean value of transmissivity obtained for the aquifer is 169 m2 day−1 while analysis of the transmissivity revealed that about 6% of the study area has greatest potential for a productive aquifer. The study also revealed that the underground water flows in the northeast–southwest direction. The hydro geochemical analysis of water samples showed that some parameters such as lead, color and pH exceeded the permissible limits, which were established by Federal Environmental Protection Agency and the World Health Organization. It is concluded from the water quality index (WQI) that the groundwater is of poor quality and requires some remediation before it can be used for domestic and industrial purposes