Application of 2-D and 3-D Geo-electrical Resistivity Tomography and Geotechnical Soil Evaluation for Engineering Site Investigation:A Case Study of Okerenkoko Primary School,Warri-Southwest,Delta State,Nigeria

In the design of building structures,joint efforts must be decided to resolve the depth of competent layers across the intended site to safeguard the durability of civil engineering structures and to avert the disastrous consequences of structural failure and collapse.In this study,an integrated methodology that employed DC resistivity tomography involving 2-D and 3-D techniques and geotechnical-soil analysis was used to evaluate subsoil conditions for engineering site investigation at Okerenkoko primary school,in the Warri-southwest area of Delta State,to adduce the phenomena responsible for the visible cracks/structural failure observed in the buildings.The results obtained brought to light the geological structure beneath the subsurface,which consists of four geoelectric layers identified as topsoil,dry/lithified upper sandy layer,wet sand(water-saturated)and peat/clay/sandy clayey soil(highly water-saturated).The deeply-seated peat/clay materials(ρ≤20Ωm)were delineated in the study area to the depths of 17.1 m and 19.8 m from 2-D and 3-D tomography respectively.3-D images presented as horizontal depth slices revealed the dominance of very low resistivity materials i.e.peat/clay/sandy clay within the fourth,fifth and sixth layers at depths ranging from 8.68-12.5 m,12.5-16.9 m and 16.9-21.9 m respectively.The dominance of mechanically unstable peat/clay/sandy clay layers beneath the subsurface,which are highly mobile in response to volumetric changes,is responsible for the noticeable cracks/failure detected on structures within the study site.These observations were validated by a geotechnical test of soil samples in the study area.Atterberg’s limits of the samples revealed plasticity indices of zero.Thus,the soil samples within the depth analyzed were representatives of sandy soil that does not possess any plasticity.The methods justifiably provided relevant information on the subsurface geology beneath the study site and should be appropriated as major tools for engineering site assessment/geotechnical projects.

Achieving Sustainable Use and Management of Water Resources for Irrigation in Nigeria

Water resource is available in Nigeria to meet water demand for domestic,agricultural and industrial use.If well enhanced and protected from various source of pollution.However,less information is available on suitability of water resources for irrigation use in Nigeria.This article reviews literature of the past with regards to influence of geogenic and anthropogenic activities on water resource for irrigation purpose in Nigeria and also to explain the current state of suitability of water resource for irrigation studies in Nigeria and gaps in studies.It also summarizes future ways on water resource management and preventive measure for water resource pollution for irrigation use.Related articles were downloaded from Google scholar in water-related issues.This paper tends to review previous article on water resource in Nigeria,and its suitability for irrigation.The primary aim of this paper is to produce a synoptic overview of the water resources in Nigeria and its suitability for irrigation use.From paper reviewed it was observed that 89%of water resources was considered suitable for irrigation.

Evaluation of Heavy Metals Concentrations in Oreochromis niloticus and Clarias gariepinus from River and Aquaculture Systems within Owerri Metropolis,Imo State Nigeria

People tend to rely upon fish as a source of cheap animal protein and a vital resource to sustain life.Oreochromis niloticus(tilapia fish)and Clarias gariepinus(cat fish)were collected from two rivers(Nworie and Otamiri rivers)and two fish ponds(FUTO and Philip’s fish ponds in Owerri municipal).The heavy metals analyzed were mercury(Hg),cadmium(Cd),iron(Fe),nickel(Ni),zinc(Zn),lead(Pb),and chromium(Cr)using FS 240 Varianatomic absorption spectrophotometer(AAS)SpectrAA.Catfish accumulated high level of Hg concentrations(>1.40 ppm)in the sample sites,Cd concentration was also high in cat fish(8.33 ppm)sampled from Nworie river while the other sample sites recorded<1 ppm.Also,Fe recorded concentrations above 4 ppm with highest concentration of 30.8 ppm;however,tilapia fish accumulated more Fe concentrations than the cat fish.Heavy metals values in the fishes were above the maximum permissible limits of established standards for fish consumption.Data collected were subjected to t-test and analysis of variance(ANOVA),and there was no statistical difference(p>0.05)between the heavy metals contents of fishes from the rivers and fish ponds studied.The total heavy metals concentrations studied accumulated from the different sample sites were in this order:tilapia fish:Nworie river(5.96±4.36)>Otamiri river(4.87±3.32)>Philip’s pond(4.87±3.19)>FUTO pond(1.62±1.40)while in cat fish:Nworie river(4.02±1.66)>Philip’s pond(3.60±2.10)>Otamiri river(2.43±1.54)>FUTO pond(2.27±1.38).There is need for periodic monitoring and assessment of heavy metals in water bodies and various aquatic lives that serve as a source of food to human.

Assessment of Drought Vulnerability and Occurrence Zones in North Central Nigeria

Assessment of drought vulnerability and occurrence zones in North Central Nigeria was carried out in this study using standardized Precipitation Index (SPI). The Standardized Precipitation Index (SPI) 12 months’ time scale was computed from long-term rainfall data between 1960 and 2015 obtained from the Nigerian Meteorological Agency (NIMET) Abuja. The SPI results were further subjected to Mann-Kendal and Sen’s slope analysis for trend detection. To assess the vulnerability of drought and occurrence zones, the SPI and other geo-spatial techniques were employed to generate drought vulnerability maps for three epochs: 2000-2005, 2005-2010 and 2010-2015 respectively. The SPI values were interpolated using Inverse Weighted (IDW) techniques in ArcGIS10.5 to generate the vulnerability maps for the selected model years. The outcome of drought trend and vulnerability maps reveals increasing drought trend dominated by near normal and moderate conditions in Abuja, Ilorin and Lokoja while moderate and severe droughts were observed in Minna and Jos. The study therefore recommends holistic drought monitoring and management strategies in order to mitigate its adverse impact on water resources and rainfall-dependent agriculture.

Screening of Human Phycotoxin Poisoning Symptoms in Coastal Communities of Nigeria: Socio-Economic Consideration of Harmful Algal Blooms

A screening of human phycotoxin poisoning symptoms was done in the coastal communities of Nigeria, every quarter for one year, using structured questionnaires. A multi-stage sampling technique consisting of cluster, snowballing, convenience purposive and random sampling was applied in the study. Based on the responses, a total of 17 Harmful algal toxin-related poisoning symptoms were recorded from respondents, who experienced these symptoms from seafood consumption. The symptoms were Balance difficulty, Breathing difficulty, Burning sensation, Chills, Confusion, Diarrhea, Dizziness, Body itching, Headache, Memory loss, Mouth tingling, Muscle pain, Nausea, Rashes, Abdominal pain, Tiredness and Vomiting. These could be grouped into five categories of diseases namely, Respiratory, Gastrointestinal, Neurological, Dermatological, and Musculo-Skeletal symptoms. The most commonly experienced symptoms were vomiting (24%), mouth tingling (21%), Nausea (14%), diarrhea (11%), headache (10%), tiredness (9%) and body itching (8%) and the least were muscle pain, rashes, confusion, chills, dizziness, balance difficulty burning sensation, breathing difficulty and abdominal pain. Statistical analyses revealed a nexus and significant relationship between visible symptoms and: seafood;season;water colour;habitats/environment of dead seafood and age of respondents. Symptoms enlisted are reminiscent of harmful algal blooms, with grave consequences for public health, commercial fisheries, recreation, tourism, monitoring/management. Therefore, preventive measures, requiring routine monitoring of water bodies, coupled with greater public awareness is suggested for early detection of occurrence of toxin-producing symptoms.

Assessment of Geologic Controls of Flooding in Parts of OBIO/AKPOR L.G.A., Rivers State, Nigeria

Flooding of Municipal areas is a frequent environmental occurrence in Rivers State that occurs when rainfall runoff meets land surfaces with low water absorbing capacity or when it overwhelms drainage channels.In order to assess the flood situation in the study area,an integrated method which involves field-measurement,geographic information system(GIS),laboratory analysis of soil samples and topographic studies were employed.Digital elevation model of the study area reveals that the flooded areas are situated in areas with elevations lower than its surrounding,thereby acting as a natural basin to retain flood waters after rainfall.Four holes were drilled to depth of 3 m to obtain soil samples at 1 m sampling interval,from which laboratory analysis was carried out to determine some geotechnical parameters such as soil’s particle size,specific gravity,bulk density,porosity,moisture content,permeability and hydraulic conductivity.Results of the analysis show that permeability,hydraulic conductivity and porosity diminishes with respect to depth.The soil in the flooded areas have high fines content(silt and clay),high bulk density which increase with depth and a specific gravity that is typical of organic rich soils that contain sand mixed with a considerable amount of fines.At Nkpolu,mean permeability rates of 0.003 cm/sec,0.009 cm/sec and 0.033 cm/sec were obtained at 1,2 and 3 m respectively.At Eneka,mean permeability rates of 0.011 cm/sec,0.018 cm/sec and 0.014 cm/sec were obtained at 1,2 and 3m respectively,while at Rukpokwu,mean Permeability rates of 0.021 cm/sec was obtained at 1 m,while 0.006 cm/sec was obtained at 2 and 3 m respectively.The mean hydraulic conductivity for the locations under study is of the order of 10-4 ft/day.This study has shown that the flooded areas are located in low lying urban areas which act as basins,therefore,the top soil is crusted with highly compacted soil horizons beneath.With high and frequent rainfall in the region which generates a lot of runoff,in addition to poor drainage system,flooding in the study area occurs frequently.Therefore,construction and maintenance of efficient drainage channels for an effective solution to urban pluvial flooding in the study area are thereby recommended.

Use of Soil Physicochemical Properties in Assessment of Soil Erosion: A Case Study of Agbor, South-South Nigeria

The study area is one of the areas in the South-South region of Nigeria that has been ravaged by erosion.This has led to loss of infrastructures and impact on the livelihood of the inhabitants of the study area.In this study,the physio-chemical of soil in Agbor and its neighboring communities were assessed in eleven different locations.A total of eleven soil samples,consisting of 5 samples each at a depth of 0–200 cm were taken in accordance with the clarification of different horizons.The samples were air-dried,crushed and sieved in 2mm mesh sieve then subjected to analysis for both physical and chemical properties in the laboratory.The physiochemical analysis results showed that pH value ranges from 5.0 to 6.3 indicating very strongly acidic to strongly acidic.Bulk density ranged from 1.29 to1.35 indicating a slight increase due to the presence of sand fraction.And low level of porosity which ranged from 49.4 to 50.9.The low level obtained from Total Organic Matter(TOM)indicates intense rainfall and constant leaching.The low Ca,Mg,K+and Na+values indicate intense rainfall and leaching problems.The values obtained from Al3+,H+,EA and P revealed a slight increase and cause of acidity nature across eleven soil test sites.The properties showed by all soils revealed that they are vulnerable to weathering,leaching,easy removal by runoff and low resistivity.

Petroleum Filling Stations and Their Impact on the Environment in Nigeria

The poor state of the environment,especially in urban areas,has become a major global issue,with developing countries such as Nigeria voicing growing concern.There is a scarcity of knowledge on the environmental impact of PFSs as a result of the loss of life and property,as well as other serious socio-economic implications of non-compliance with PFSs siting criteria.The historical literature on the impact of residential buildings,the environment,and human health on PFSs in Nigeria,as well as the study’s gap,is examined in this research.It also outlines DPR compliance with PFSs location as well as established criteria for prohibiting PFS siting in Nigeria’s states.Relevant publications on PFSs-related topics were downloaded from Google Scholar.The goal of this study is to look back on a previous essay about PFSs in Nigeria and its impacts on the environment and human health.This study’s main purpose is to give a complete overview of Nigerian PFSs.According to the article analyzed,the majority of PFSs were located close to residents,with setbacks from the road and residential areas of less than 30 m in 90%of the filling stations.As a result,the landowners can band together to argue that a facility that is improperly sited cannot be built.A great deal of public participation is required.A campaign should be launched to raise awareness among filling station owners and other developers of the dangers of non-compliance with established norms.All violators of the established norms,as well as corrupt officials of enforcement agencies/bodies,should face open punishment so that others might learn their lessons.Finally,appropriate planning is required to allow future road expansion.

Performance Assessment of a Heat Recovery Unit Utilizing Turbine with Variable Inlet Guide Vanes Configuration for Application in Passenger Vehicles

This study explores the potentials of employing an Organic Rankine Cycle (ORC) system with variable inlet guide vanes (VIV) turbine geometry designed on a GT-Suite platform for effective exhaust heat recovery (EHR) application onboard passenger vehicles. The ORC model simulation was based on vehicle speed mode using R245fa as working fluid to assess the thermal performance of the ORC system when utilizing modified turbine geometry. Interestingly, the model achieved a very improved performance in contrast to the model without a modified turbine configuration. The results revealed the average 2.32 kW ORC net output, 4.93% thermal efficiency, 6.1% mechanical efficiency, and 5.0% improved brake specific fuel consumption (BSFC) for the developed model. As determined by the performance indicators, these promising results from the model study show the prospect of EHR technology application in the transportation sector for reduction in exhaust emissions and fuel savings.

Thyroid Disrupting Activities in Wastewater and Surface Waters: A Review of Their <i>In Vitro</i>Analyses

The developmental and reproductive effects of endocrine disruption on humans and wildlife rank among the most threatening of all environmental health concerns. Particularly vulnerable to chemical assaults are the hypothalamic-pituitary-gonadal (HPG) axis and the hypothalamic-pituitary-thyroid (HPT) axis of the endocrine system. While the effects of endocrine disrupting chemicals (EDCs) on the HPG axis have been the subject of intense research efforts, with comprehensive elucidation, a lot remains to be clarified on the effects of EDCs on thyroid functions. For instance, there are no clear-cut biomarkers of exposure and effects of thyroid disrupting chemicals (TDCs) in intact organisms. Consequently, a number of in vitro assays have been developed, and are particularly useful for the identification and mechanistic characterization of potential TDCs considering the increasing number of EDCs that are being released into the environment. However, with the in vitro assays, studies suggest that a plausible major mode of action of TDCs, thyroid hormone receptor (THR) agonist activity, is not environmentally relevant. Here, we reviewed in vitro detection of TDCs activities in wastewater and surface waters. Data strongly suggest that cell lines may be responsible for the less frequent detection of THR agonist activity in wastewater and surface water. It was concluded that the development of reporter gene assays with thyroid hormone function related cell lines, is required.

Investigation of Power Supply to Subsea Loads from High Voltage Electric Source Using Modular Direct Current Scheme

Subsea power converters have been identified in recent researches as a potential means of supplying power to subsea loads and this technology has been seen as a means to reduce the reliance on offshore platforms. This study analyses all electric subsea high power system for power generation and transmission in the offshore oil and gas industry for sustainable subsea development. In order to accomplish the analysis of power generation and transmission to subsea loads, the MAT lab SIMULINK software was employed to ascertain losses arising from the transmission of power to subsea systems. Data from Agbara and Akpo fields, all located in Nigeria, were analysed using the MSDC model as an alternative power source for power generation and transmission to all subsea loads. When the voltage loss between a step out distance at 30 km and 200 km was compared for the Akpo oil field, the plots indicate a significant loss in voltage. The RMS value of voltage loss increased from 0.8874 at a step out distance 30 km to 0.9449 for 200 km.

Hydrocarbon Play Assessment of “Oswil” Field, Onshore Niger Delta Region

Hydrocarbon play assessment of any field involves the evaluation of the production capacity of hydrocarbon reservoir unit in the field.This involves detail study of the reservoir petrophysical properties and geological interpretation of structures suitable for hydrocarbon accumulation in the field as observed from seismic reflection images.This study details the assessment of hydrocarbon play in OSWIL field onshore in Niger Delta,with the intent of appraising its productivity using a combination of seismic,well logs,petrophysical parameters and volumetric estimation using proven techniques which involves an integrated methodology.Two reservoir windows“R1”and“R2”were defined from five wells OSWIL-02,04,06,07 and 12.The top and base of each reservoir window was delineated from the wells.Structural interpretation for inline 6975 revealed two horizons(X and Y)and eight faults labelled(F1,F2,F6,F8,F10,F16,F17 and F18).Five faults(F1,F6,F10,F17 and F18)were identified as synthetic faults and dip basin wards while three faults(F2,F8 and F16)were identified as antithetic faults and dips landwards.Time-depth structural map at top of reservoirs R1 and R2 revealed structural highs and closures.These observations are characteristics of growth structures(faults)which depicts the tectonic style of the Niger Delta.Results of petrophysical evaluation for reservoirs“R1”and“R2”across the five wells were analysed.For reservoir“R1”effective porosity values of 27%,26%,23%,20%and 22%were obtained for wells OSWIL-04,12,07,06 and 02 respectively with an average of 23.6%,while for reservoir“R2”effective porosity values of 26%,22%,21%,24%and 23%for wells OSWIL-04,12,07,06 and 02 were obtained respectively with an average of 23.2%.This porosity values correspond with the already established porosity range of 28-32%within the Agbada formation of the Niger Delta.Permeability index of the order(K>100mD)were obtained for both reservoirs across the five wells and is rated very good.Hydrocarbon saturation(Shc)across the five wells averages at 61.6%for reservoir“R1”and 67.4%for reservoir“R2”.Result of petrophysical model for porosity,permeability and water saturation reveal that the reservoir system in R1 and R2 is fault assisted and fluid flow within both reservoirs is aided by presence of effective porosity and faulting.Volumetric estimation for both reservoirs showed that reservoir R1 contains an estimate of 455×106 STB of hydrocarbon in place,while reservoir R2 contains an estimate of 683×106 STB of hydrocarbon in place.These findings impact positively on hydrocarbon production in the field and affirm that the two reservoirs R1 and R2 are highly prospective.

Exergoeconomic Evaluation and Optimization of Dual Pressure Organic Rankine Cycle (ORC) for Geothermal Heat Source Utilization

In the present study, a dual-pressure organic Rankine cycle (DORC) driven by geothermal hot water for electricity production is developed, investigated and optimized from the energy, exergy and exergoeconomic viewpoint. A parametric study is conducted to determine the effect of high-stage pressure and low-stage pressure variation on the system thermodynamic and exergoeconomic performance. The DORC is further optimized to obtain maximum exergy efficiency optimized design (EEOD case) and minimum product cost optimized design (PCOD case). The exergy efficiency and unit cost of power produced for the optimization of EEOD case and PCOD case are 33.03% and 3.059 cent/kWh, which are 0.3% and 17.4% improvement over base case, respectively. The PCOD case proved to be the best, with respect to minimum unit cost of power produced and net power output over the base case and EEOD case.