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Journal01 Aug 2026
Hydro-Physicochemical Quality and Microbial Safety of Water Used by Food Vendors in Oke-Owa, Ogun, Southwestern Nigeria: Implications for WASH, Hydrological Vulnerability, and Public Health
Inadequate hygiene and unsafe water in informal food-vending areas present serious public-health hazards particularly in the fast-urbanizing areas of Nigeria. In this paper, the hydro-physicochemical quality, microbial contamination and hygienic determinants of the water sources used by 100 food vendors were evaluated in Oke-Owa Community, Ijebu-Ode, Ogun State. The samples of water collected at five widespread sources of vendors were evaluated in terms of pH, TDS, alkalinity, hardness, ORP, ions, and heavy metals by using the standard guidelines of American Public Health Association. E. coli, Salmonella spp, and total count of coliform was measured using microbiological tests. The findings indicated that the water was very acidic (pH 4.00 – 4.50), low TDS (21.5 – 30 ppm), zero alkalinity, low traces of hardness, and high ORP (159 – 232 mV) meaning that it had high oxidizing capacity and low buffering capacity. Contamination with microorganisms was extreme: E. coli was detected in 74 5 percent of samples, Salmonella spp. in 68 percent and the average TCC of 8.36 ± 2.03 × 10 CFU/mL. Logistic regression revealed that training of vendors and access to clean water were significantly associated with compliance to hygiene. The result of Principal Component Analysis revealed three behavioral domains that include personal hygiene, cross-contamination control, and environmental sanitation. Results point to hydrological instability, inadequate water governance, and water sanitation and hygiene (WASH) deficits that all increase health vulnerabilities. The adoption of the World Health Organization Water Safety Plan strategies is vital in protecting the health of the people in informal markets.
Read MoreJournal01 Aug 2026
Field Evaluation of a Tide-Driven Siphon Biostimulation System for Subsurface Hydrocarbon Remediation in Opu-Nembe, Nigeria
This study designs, constructs, and field-validates the long-term performance of a zero-power, Tide-Driven Siphon Biostimulation (TDSB) system. The installation is configured to accelerate the in-situ degradation of persistent total petroleum hydrocarbon (TPH) mass entombed within low-permeability cohesive clays following the 38-day uncontained wellhead blowout at the Santa Barbara South Well-1 (OML29) in Nembe, Bayelsa State, Nigeria. A pilot-scale field implementation was executed across three independent, randomized treatment plots containing nested monitoring clusters. Subsurface fluid delivery lines were charged with an amphiphilic rhamnolipid biosurfactant and dissolved macronutrient solution (C:N:P 100:10:1). Soil cores (n=9 replicates per milestone) were extracted from a core depth profile of 0.75m to 1.25m over a 24-month horizon. Residual hydrocarbon concentrations were quantified via gas chromatography-mass spectrometry in compliance with US EPA Method 8015C standards. Changing structural soil parameters were derived using triaxial shear cell testing under ASTM standard guidelines. Field data confirm that the system successfully harnessed the natural potential energy of local semi-diurnal spring tides (2.2m maximum head). When the rising tide head differential breached the network's check- valve activation threshold (ÄHtidal > + 0.4m) , the gravity feed lines automatically pulsed the remediation solution into the clay matrix, overriding capillary entry resistance. Over the 24-month monitoring timeline, the TDSB network dropped mean subsurface soil TPH concentrations from an acute baseline of 42,500±1,850mg/kg down to 92±8mg/kg, successfully clearing the national EGASPIN intervention target limit (5,000mg/kg), while traditional natural attenuation control fields remained stalled at 8,450±520mg/kg due to severe macronutrient exhaustion. This accelerated hydrocarbon removal eliminated internal pore-fluid blocks, driving an increase in structural mineral confining stress from a liquefied state of -20.0kPa back to a consolidated baseline of +33.4kPa to stabilize the slopeface against further erosion. These pilot-scale findings suggest that leveraging natural hydrostatic cycles provides a viable, zero-power mechanism to remediate deep contaminant sinks in isolated basins. Coastal remediation frameworks should incorporate tidal potential head variations to eliminate the need for external electrical grids during in-situ soil remediation campaigns.
Read MoreJournal01 Aug 2026
Geotechnical Characterization and Deformation Susceptibility Assessment of Lateritic Subgrade Materials along Six Road Corridors in Ondo and Edo States, Southern Nigeria
Residual soils formed by in-situ weathering are widely used as pavement subgrade in humid tropical regions, yet the reliability of plasticity-based classification for anticipating subgrade competence across contrasting weathering regimes remains poorly quantified outside site-specific case studies. This study examines ninety-five subgrade soil samples collected along six road corridors totalling approximately 180 km in Ondo and Edo States, southern Nigeria, forming two geographically separate corridor networks that span basement-complex (schist belt) and coastal-plain sedimentary terrains. Particle size distribution, Atterberg limits, compaction characteristics and California Bearing Ratio were determined in accordance with BS 1377:1990, using British Standard heavy compaction, and soils were classified using the AASHTO system. Liquid limit ranged from 15.2 to 65.2%, plasticity index from 7.3 to 45.1%, maximum dry density from 1.13 to 2.43 g/cm³, and four-day soaked CBR from 1 to 47%. Thirty-six samples (38%) classified as A-7-6, with a mean soaked CBR of 5.9%, and 61 of 95 samples (64%) recorded soaked CBR below the 10% benchmark adopted here for subgrade assessment. Soaked CBR differed significantly among AASHTO groups (Kruskal–Wallis H = 23.3, p < 0.001), although the ordering was partial rather than monotonic, with adjacent groups statistically indistinguishable. Plasticity index showed a stronger bivariate correlation with soaked CBR (r = - 0.49) than the clay-size fraction (r = +0.39), the latter being positive and sensitive to influential observations. The results indicate that plasticity indices, rather than grain-size composition alone, provide the more dependable first-order screening of subgrade risk in this terrain.
Read MoreJournal01 Aug 2026
Induced Soil Liquefaction and Critical Hydraulic Gradient Variations in Estuarine Mudflats Subjected to Hydrophobic Hydrocarbon Infusion in Opu-Nembe, Nigeria
This study investigates the mechanisms driving widespread riverbank slumping and monotonic soil liquefaction in the intertidal zones of the Nembe estuarine network following the 38-day, uncontained, high-pressure crude-oil blowout at Santa Barbara South Well-1 (OML 29). Undisturbed organic-rich silty clay cores (Chikoko soils) were collected along the CC-01 core axis across 47 impacted communities under macrotidal conditions. Geotechnical index profiling and fluid-interaction screening followed ASTM D4318 and ASTM D2216, while high-pressure cyclic triaxial shear testing (ASTM D5311) and automated pneumatic shear-cell systems quantified multiphase soil behaviour and fluid-dependent strain anomalies. The dataset calibrated an extended Bishop multiphase effective- stress tensor model incorporating nonlinear log-likelihood change-point analysis to identify structural degradation thresholds during 2.0-m semidiurnal tidal oscillations. Crude-oil infusion induced severe hydrophobicity, increasing Water Drop Penetration Time beyond 3,600 s and forming an impermeable surface crust. During rapid low-tide drawdown, this crust acted as a hydraulic seal, restricting pore-fluid dissipation and causing excess pore-oil pressure to accumulate behind slope faces. Effective vertical confining stress approached zero, triggering sudden monotonic fluidization. H ydrocarbon lubrication of clay platelets reduced cohesion (c ' ) from 12.50 to 4.20 kPa and friction angle (ö ' ) from 31.8° to 2.3°. The critical hydraulic gradient declined by 38.2%, enabling normal tidal seepage forces to exceed slope-yield resistance and i nitiate catastrophic rotational bank collapse. These failures displaced contaminated topsoil into anoxic horizons 0.5–1.5 m deep, burying weathered polycyclic aromatic hydrocarbons (PAHs) and trace heavy metals. This geotechnical entombment limits oxygen-dependent biodegradation and atmospheric weathering, creating persistent pollutant reservoirs that slowly leach into groundwater and the coastal food web. Conventional shoreline washing is therefore inadequate; recovery requires non-destructive bank stabilization combined with targeted subsurface biostimulation to treat concealed contaminant sinks safely. The findings establish a process-based basis for predicting delayed slope failure and designing safer, site-specific remediation across similar oil-impacted estuarine environments.
Read MoreJournal01 Aug 2026
Geoelectric Delineation of Aquifer Units in Bayelsa State, Nigeria: A Review of Case Studies and Groundwater Management Implication
Groundwater is Bayelsa State's principal dependable water source, but development is complicated by heterogeneous Niger Delta sediments, shallow water tables, flooding, contamination and possible saline influence. This structured narrative review synthesises geoelectric aquifer studies published from 2010 to 2026 and evaluates their management implications. Publications were identified, screened and compared by survey design, curve type, layer sequence, aquifer resistivity, depth, thickness, hydraulic properties, protective capacity, vulnerability and validation. Evidence is concentrated in Yenagoa, Ogbia, Otuoke, Opolo-Epie and Elebele and consistently indicates multilayer aquifers of fine- to coarse-grained sand separated locally by discontinuous clay, silty-clay and sandy-clay units. Schlumberger vertical electrical sounding has delineated productive horizons, guided drilling depth, assessed overburden protection and extended sparse pumping-test information. Reported parameters vary because of genuine facies changes and differences in electrode spread, sounding density, inversion, classification thresholds and calibration. Resistivity alone cannot uniquely distinguish clay, freshwater sand, saline groundwater or contamination; borehole logs, pumping tests, hydrochemistry and microbiological analyses remain essential. The review recommends locally calibrated interpretation, integrated VES-ERT investigations, systematic monitoring and abstraction control, a unified state groundwater database, wider coastal coverage and regional aquifer correlation to support sustainable development and protection.
Read MoreJournal01 Aug 2026
Integrated Geotechnical-Mineralogical Characterization of Crystalline Basement Soils: Implications for Pavement Design and Performance in Tropical Terrains
In tropical regions, soils derived from crystalline basement rocks are widely used in road construction; however, their engineering performance is often inadequately characterized due to limited spatial sampling and insufficient integration of geological controls. This study evaluates the geotechnical and mineralogical characteristics of crystalline-derived soils to assess their suitability for pavement applications. Fifty samples collected across multiple lithological units were analyzed for index properties, compaction parameters, California Bearing Ratio (CBR), and mineral composition using X-ray diffraction (XRD). The soils are predominantly fine-grained, with fine content ranged up to 59.6% and generally poor gradation. Atterberg limits indicate low to moderately high plasticity (liquid limit: 14.3–53%; plasticity index: 1.0 - 24.0%), while soil activity ranges from 0.3 to 2.85, schist-derived soils exhibiting the highest variability (mean 1.85) across the lithologies. Compaction results show mean maximum dry density and optimum moisture content of 1.80 Mg/m³ and 16.9%, respectively. Unsoaked CBR values (40–54%) indicate moderate strength, but a marked reduction under soaked conditions (18–25%) reflects significant moisture susceptibility. XRD analysis reveals that the dominant clay minerals, expressed as mean values are kaolinite (31.5%), pyrophyllite (18.7%), chlorite (18.4%, and illite (15.7%). This finding offers a mechanistic explanation for the observed swelling behavior and the pronounced reduction in strength under saturated conditions which highlights the need for careful material selection and appropriate stabilization measures in pavement design. The study demonstrate that variations in parent lithology and clay mineral assemblages exert a strong control on the engineering performance of the soils, thus emphasizing the importance of integrating mineralogical data with conventional geotechnical testing to improve the reliability of subgrade evaluation in crystalline basement terrains.
Read MoreJournal01 Aug 2026
Soil Erodibility Characterization of the Southwestern Nigerian Basement and Sedimentary Terrains Using Geochemical and Geotechnical Techniques
Our lack of full understanding of the factors affecting erodibility in all geological terrains, especially the combined geochemical and geotechnical effects, remains a challenge in geotechnical engineering. In this research, the erodibility of soils from basement and sedimentary terrains, Southwest Nigeria, was investigated through a combined geotechnical-geochemical approach. The soil samples from Akure (Basement Complex of Nigeria) and Ode-Irele (sedimentary basin) were tested for classification, consistency limits, compaction, California Bearing Ratio (CBR) and X-ray fluorescence (XRF). The findings reveal that basement soils have higher sesquioxides (Al O + Fe2O ) content, laterization, bonding, cohesion (as high as 120.2 kPa), internal friction angle (as high as 32.9°) and CBR values (as high as 70 %), well-graded, coarse grained clayey soil and classified as CI - CH soils. By contrast, sedimentary soils contain higher SiO , lower cohesion (2.0 kPa), well-graded, coarse grained silty sand soil and classified as CL - ML soil type. Soils found on basement terrain have better bonding, are less erodible and are more amenable to stabilization than sedimentary terrain soils (STS). In comparison, STS have lower cohesion-frictional characteristics, higher erosion, soil loss, and soil degradation potential. The greater soil loss ratio and erodibility factors for STS reflect their susceptibility to environmental degradation and landslides. These variations in soil properties reflect different geological formation histories, which result in different degrees of weathering, soil structure and permeability. This study underscores the need to consider terrain-specific soil characteristics for erosion risk analysis and infrastructure development.
Read MoreJournal01 Aug 2026
Integrated 2D Electrical Resistivity Tomography and Hydrochemical Assessment of Hydrocarbon Contamination around Oil Tank Farms in Apapa, Southwestern Nigeria
Oil spills from tank farms in Apapa, southwestern Nigeria, pose significant risks to groundwater, surface water, and soil due to the area's geologically vulnerable coastal materials. This study assessed the environmental impact of oil spillage at two facilities, Wesb Oil and Rein Oil, focusing on subsurface conditions and water quality. Two - dimensional Electrical Resistivity Tomography (ERT) using a Wenner array was conducted along four traverses to delineate subsurface structures. In addition, physicoche mical, geochemical, and microbiological analyses were performed on water samples from both sites and a control location. ERT results identified two to three geoelectric layers, with high-resistivity anomalies (>110 Ùm) at Wesb Oil, indicating the presence of the hydrocarbon plume. The Water quality analysis showed marked deviations from World Health Organization standards. All samples were acidic, while Wesb Oil recorded elevated salinity, electrical conductivity, total dissolved solids, biochemical oxygen demand, and heavy metal concentrations, indicating severe contamination. Microbiological results revealed high microbial loads, including fecal contamination at Wesb Oil and the control site, as well as hydrocarbon-utilizing microorganisms, confirming petroleum pollution and associated health risks. In contrast, Rein Oil showed no detectable contaminant plume, likely due to effective containment measures that limited hydrocarbon infiltration. Overall, Wesb Oil is significantly polluted and poses a serious threat to groundwater and the surrounding ecosystem, whereas Rein Oil demonstrates better environmental management. It is recommended that bioremediation and improved containment systems such as concrete floor around the gantry be implemented at Wesb Oil, alongside continuous environmental monitoring to protect public health and ensure sustainability.
Read MoreJournal01 Aug 2026
Hydrogeophysical and Geotechnical Characterization of Soil and Groundwater at Two Crude Oil Spill Sites in Central and Eastern Niger Delta
Crude oil spills in the Niger Delta continue to impair shallow soils, groundwater quality, ecosystem services, and the geotechnical behaviour of near-surface sediments. This study presents an integrated geochemical, hydrogeological, geotechnical, and geoelectrical characterization of two spill-impacted communities, Agbura in Bayelsa State and Bodo in Rivers State. Five boreholes and nine vertical electrical soundings were established at each site to evaluate contaminant distribution relative to spill source, groundwater flow direction, depth of infiltration, and textural controls on contaminant mobility. Groundwater and soil samples were analysed for physicochemical parameters, total petroleum hydrocarbon (TPH), and selected heavy metals, while grain-size and Atterberg-limit tests were used to classify soils and infer hydraulic behaviour. Hydraulic-head contouring showed northeast–southwest flow at Agbura and northwest–southeast flow at Bodo, indicating preferential migration toward downslope receptors. Groundwater close to the spill centres recorded elevated turbidity, chemical oxygen demand, biochemical oxygen demand, and TPH, with the poorest quality at closest to spill sites in both communities. Water quality index status ranged from good to unsuitable, and heavy-metal pollution indices showed moderate to high pollution intensity near the impact points.The soils comprise clay, sandy clay, clayey sand, silty sand, and poorly graded sand, with average hydraulic conductivity of 3.11 × 10?6 m/s at Agbura and 8.53 × 10?6 m/s at Bodo. Corresp ondingly, spill-affected geoelectric layers displayed anomalously high resistivity, commonly between 500 and 2000 Ùm. The results demonstrate that the combined use of geochemical testing, geotechnical evaluation, and geoelectrical sounding provides a robus t basis for site screening, vulnerability assessment, and remediation planning in coastal deltaic terrain.
Read MoreJournal01 Aug 2026
Integrated Geotechnical and Geophysical Evaluation of Soils for Determination of Building Site Suitability in Parts of Bayelsa State
Assessment of foundation conditions in the Niger Delta is complicated by shallow groundwater, lateral lithologic variability, and weak fine-grained near-surface deposits. This study evaluates building-site suitability in selected parts of Bayelsa State, southern Nigeria, using an integrated geotechnical–geophysical approach. Borehole logging, laboratory determination of index properties, Standard Penetration Testing (SPT), Vertical Electrical Sounding (VES), and Multichannel Analysis of Surface Waves (MASW) were combined to characterize lithology, moisture condition, resistivity structure, stiffness, and bearing competence. The shallow subsurface is dominated by soft clay, silty clay, and sandy clay, whereas deeper horizons consist mainly of clayey sand, silty sand, and dense to poorly graded sand. Moisture content ranges from 18.3 to 41.1%, liquid limit from 22 to 73%, and plasticity index from 6 to 41%, indicating wet and moderately to highly plastic shallow soils. SPT N-values increase from about 6 to 20 with depth, reflecting progressive improvement in competence. VES delineates 4–6 geoelectric layers, with shallow conductive clay-rich zones showing resistivity values of 35–63 Ùm in Amassoma and Tombia, whereas deeper sandy units in Opolo attain up to 3278 Ùm. MASW-derived shear-wave velocity increases from about 176 to 606 m/s with depth. Comparative bearing-capacity estimates from SPT, MASW, and laboratory testing show close agreement, with shallow values generally below 85 kPa and deeper sandy horizons commonly exceeding 120 kPa and reaching about 213 kPa. The results demonstrate that the upper 2–3 m are generally unsuitable for untreated shallow foundations, whereas deeper sandy horizons constitute the preferred competent founding strata.
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