Jul 2026· Sriwijaya Journal of Environment· Vol 11, pp. 85-94· 0 citations· 20 references
Abstract
Background: Oil spillage is a major driver of soil degradation in the Niger Delta, yet integrated, site-specific assessments coupling metals, polycyclic aromatic hydrocarbons (PAHs) and quantitative risk remain scarce.
Objective: This study assessed the contamination status, source structure and ecological and human-health risk of soils at a crude-oil spill site in Okpohovor, Udu Local Government Area, Delta State, Nigeria.
Methods: Soils from five points (S1–S5) and a control station were sampled at two depths (0–15 and 15–30 cm). pH, electrical conductivity, total organic carbon, particle size and nine metals were determined by flame atomic absorption spectrophotometry, and 16 priority PAHs by GC–MS. Pollution indices, principal component analysis (PCA), one-way ANOVA with effect sizes, and BaP-equivalent, hazard-index and incremental lifetime cancer-risk models were applied.
Results: Soils were strongly acidic (pH 3.00–3.70) and sandy. All metals were below Department of Petroleum Resources (DPR) target values except cadmium (0.05–2.55 mg/kg), which reached the pollution range in 60% of samples. Clay differed significantly between sites (F=10.133, p=0.013, η²=0.890). PCA separated a lithogenic Pb–Cr–Ni–Fe association (PC1, 32.0%) from a cadmium-driven signal. The ecological risk index (9–263) was cadmium-dominated. ΣPAH reached 81,327 µg/kg from mixed petrogenic–pyrogenic sources; hazard indices were mostly below 1 but total cancer risk exceeded 1×10⁻⁶.
Conclusion: Cadmium and carcinogenic PAHs are the priority contaminants, posing food-chain and public-health risks that warrant targeted remediation and sustained monitoring.
Borehole water is a major drinking water source in Owerri West LGA, Imo State, Nigeria, but fuel
stations within residential areas raise concerns over groundwater contamination by polycyclic
aromatic hydrocarbons (PAHs). This study assessed concentrations of the 16 USEPA priority
PAHs in borehole water near three fuel stations (Nekede, Orogwe, Obinze), evaluated health risks
to adults and children, and identified probable contamination sources. Twenty-seven samples were
collected in the dry season from fuel-station and nearby residential boreholes (25–625 m away).
Physicochemical parameters were analyzed per APHA (2017); PAHs were extracted (USEPA
Method 3510C) and quantified by GC-MS. Health risk was assessed using the USEPA (2014)
deterministic model, with source apportionment via diagnostic ratios and PCA. All
physicochemical parameters met WHO/USEPA limits. Total PAHs (Σ16PAHs) ranged from
0.112–0.217 mg/L, with benzo(a)pyrene exceeding the USEPA limit (0.01 µg/L) in all fuel-station
boreholes. Hazard quotients were below 1, but benzo(a)pyrene cancer risk (7.15×10⁻⁵ adults;
1.67×10⁻⁴ children, Nekede) exceeded the USEPA threshold (1×10⁻⁶), with children ~2.3 times
more at risk. Diagnostic ratios indicated predominantly pyrogenic sources with petrogenic
contribution from fuel leaks. Despite meeting potability standards, the water posed unacceptable
carcinogenic risk, warranting setback regulations and household treatment.
D. L., Oze R. N., B. A. et al.· INTERNATIONAL JOURNAL OF CHE...· 0 citations
Aim: This study assessed the ecological risk posed by six heavy metals [lead (Pb), zinc (Zn), nickel (Ni), copper (Cu), chromium (Cr), and cadmium (Cd)] in soils and surface waters.
Study Design: Soil samples were collected at two depths (0–15 and 15–30 cm) from 12 stations across Onna, Mkpat Enin, Eastern Obolo, and Uyo in Akwa Ibom State. Surface-water samples were also collected, and Uyo served as the reference location.
Methodology: Composite soil samples were collected using a stainless-steel soil auger. Following acid digestion, metal concentrations were determined by atomic absorption spectrophotometry (AAS). The contamination factor (CF), degree of contamination (C-deg), geoaccumulation index (Igeo), single-metal ecological risk factor, and comprehensive potential ecological risk index (RI) were calculated using average-shale background values and the methods of Müller and Hakanson.
Results: Except for nickel at Onna Station 3 (57.5 mg/kg), which exceeded the adopted agricultural and residential soil guideline values, soil-metal concentrations were below the relevant limits. In surface water, lead and nickel exceeded the adopted WHO guideline values at all four locations, whereas chromium and cadmium exceeded the guidelines at two locations. Most CF and Igeo values indicated low contamination, although cadmium showed the greatest relative enrichment at several stations.
Conclusion: Although several stations, including the reference location, showed moderate-to-considerable single-metal risk from cadmium, RI remained below 150 at all soil stations, indicating low overall potential ecological risk. The results provide baseline information for environmental monitoring and remediation prioritisation in the studied oil-producing areas.
U. U. Ubong, A. D. Akpan, U. G. Isotuk· Asian Journal of Physical an...· 0 citations
The Niger Delta region of Nigeria is highly vulnerable to environmental pollution due to extensive
oil exploration and industrial activities, resulting in the contamination of aquatic ecosystems with
heavy metals and polycyclic aromatic hydrocarbons (PAHs). This study assessed the
concentrations of heavy metals and PAHs in surface water and sediments of the Khana LGA,
Rivers, Rivers State, to evaluate potential ecological and human health risks. Surface water and
sediment samples were collected from selected sampling stations within rivers in Zaakpon, Kaani,
and Bane communities in Gikana LGA and analyzed using standard physicochemical and
spectroscopic techniques, including Atomic Absorption Spectroscopy (AAS) for heavy metals and
Gas Chromatography-Mass Spectrometry (GC-MS) for PAHs. Results indicated that the mean
concentrations of heavy metals in surface water were Pb (0.285 ± 0.019 mg/L), Cd (0.013 ± 0.004
mg/L), Cr (0.044 ± 0.005 mg/L), and Fe (1.894 ± 0.196 mg/L), with several exceeding WHO and
NSDWQ limits. Sediment samples exhibited higher metal accumulation, with Cu (14.771 ± 1.074
mg/kg), Pb (29.279 ± 3.161 mg/kg), Fe (1826.925 ± 10.798 mg/kg), and Zn (136.356 ± 6.317
mg/kg), indicating sediments act as long-term sinks for metal pollutants. For PAHs, total
concentrations in water ranged from 0.167 to 1.256 mg/L (mean: 0.477 ± 0.075 mg/L), with
carcinogenic PAHs (∑cPAHs) at 0.121 ± 0.024 mg/L, exceeding WHO and USEPA guidelines.
Sediment PAH concentrations were substantially higher, ranging from 6.994 to 20.178 mg/kg
(mean: 11.866 ± 1.274 mg/kg), with both low and high molecular weight PAHs present, reflecting
mixed petrogenic and pyrogenic sources. The study concludes that the Khana Rivers are heavily
contaminated with both heavy metals and PAHs, posing serious environmental and human health
risks. Urgent interventions are recommended, including continuous monitoring of water quality,
enforcement of environmental regulations, remediation of polluted sediments, and community
awareness programs to mitigate exposure to toxic contaminants. The findings provide a crucial
baseline for future ecological risk assessment and pollution management in oil-impacted riverine
systems of the Niger Delta.
Wisdom Osamudiamen Clifford-Osawaru· IIARD International Journal...· 0 citations
This study evaluated the concentrations of polycyclic aromatic hydrocarbons (PAHs) in soil, water, and edible plants within cashew nut processing clusters in Enugu, Nigeria. Following liquid–liquid and solid–liquid extractions, the concentration of sixteen PAHs congeners were determined using gas chromatography coupled with a flame ionization detector (GC‐FID). To predict the potential sources of these PAHs, a diagnostic ratio guide was employed and principal component analysis was performed. Mutagenic equivalent concentration, human health risk assessment, and ecological risk assessment were performed. The identified PAHs had concentration range: 786.31–2589.46 µg/kg in soil, 33.78–5476.37 µg/L in water, and 561.47–3047.84 µg/kg in vegetables. Except for one location, the vegetables had higher levels of low molecular weight PAHs, while high molecular weight PAHs were more prevalent in the water. The results showed that the studied location has a fair amount of PAH pollution, mostly from pyrogenic sources though the source apportionment models predicted multi‐sources. The ecological risk assessment indicated acenaphthene to be the most contributing contaminant while the health risk evaluations indicated that consumers of water and vegetables from this area may have risk for non‐carcinogenic health problems. There were substantial mutagenic equivalent quantities, and BaP metabolites were probably responsible. The study reveals that inefficient burning of biomass and fossil fuels has resulted in significant levels of PAH contamination in the surrounding cashew nut processing clusters, and these activities should be controlled.
Edidiong S. Akwaowo, H. Abugu, J. Ihedioha· CLEAN - Soil, Air, Water· 0 citations
Heavy metal contamination poses significant ecological and public health concerns due to its persistence, toxicity, and bioaccumulative potential of toxic metals, threatening environmental quality and sustainable development. This study evaluated the distribution, pollution status, health risks, and sources of heavy metals in soils from industrial, agricultural, and residential areas of Rivers State, Nigeria, using Inductively Coupled Plasma–Mass Spectrometry (ICP-MS). Elevated concentrations of As, Mn, Se, Zn, and Co were detected across the study locations. Arsenic recorded the highest concentration in the Trans-Amadi industrial area (366.8 mg/kg), while Mn and Zn reached maximum concentrations of 1312 mg/kg and 327.9 mg/kg in Woji and Egi, respectively, exceeding the DPR limits for soil HMs. Pollution indices, including contamination factor, geo-accumulation index, enrichment factor, pollution load index, and Nemerow Integrated Pollution Index, revealed moderate to severe contamination, with the industrial zone exhibiting a NIPI value of 12.5. Health risk assessment identified ingestion as the dominant exposure pathway. Hazard quotient values for As (9.15) in the children category exceeded USEPA-acceptable limits, indicating potential non-carcinogenic risks. Carcinogenic risk assessment identified arsenic as the principal carcinogenic contaminant, with ingestion-derived Incremental Lifetime Cancer Risk (ILCR) values in the industrial area exceeding the USEPA maximum acceptable lifetime cancer risk threshold (1 × 10−4), particularly among children, whereas the carcinogenic risks associated with the other investigated metals generally remained within acceptable or tolerable limits. Source identification indicated that industrial emissions, vehicular activities, waste disposal, and agricultural practices were the primary contributors to heavy metal accumulation. These findings provide critical scientific evidence for targeted remediation, pollution prevention, and informed health-risk environmental management to protect soil quality, ecosystem integrity, and public health. The study supports evidence-based policies that advance sustainable land management, environmental protection, and progress in Rivers State, Nigeria.
Soils around petrol filling stations are exposed to polycyclic aromatic hydrocarbons (PAHs) from fuel spillage, storage tank leakage, and incomplete combustion of petroleum products. This study assessed the levels, distribution, sources and health risk of the 16 USEPA priority PAHs in soils around petrol filling stations in Kogi Central (Zone 1: Ajaokuta, Okene) and Kogi West (Zone 2: Obajana, Lokoja), Kogi State, Nigeria. Twelve soil samples from filling stations and four controls were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). Surrogate (o-terphenyl) recoveries ranged from 94.0 to 101.6%. Total PAH (Σ16PAHs) concentrations ranged from 0.540 to 5.90 µg/kg, with mean values of 2.55 µg/kg in Zone 1 and 3.45 µg/kg in Zone 2 (combined mean 3.00 µg/kg). A two-sample t-test showed significantly higher PAH concentrations at filling stations than controls (t = -2.30, p = 0.038), with no significant difference among the four towns (p = 0.094). Low molecular weight (2-3 ring) PAHs dominated the distribution (65.7%), followed by 4-ring (30.2%) and 5-6 ring PAHs (4.12%). All individual and total PAH concentrations were below the Dutch maximum permissible concentrations, indicating unpolluted soils. Diagnostic ratios (LMW/HMW = 1.91; Ant/(Ant+Phe) = 0.77; Flt/(Flt+Pyr) = 0.90; BaA/(BaA+Chr) = 0.68) revealed a predominantly pyrolytic origin for the PAHs, with a minor petrogenic contribution. The mean benzo[a]pyrene equivalent concentration (BaPeq) was 0.0595 µg/kg, far below the 600 µg/kg Canadian soil quality guideline, denoting low carcinogenic potential. The results supply baseline data for PAH monitoring in the study area and complement previously published data for Kogi East.
J. A. Kadili, Godwin John, I. S. Eneji et al.· FUDMA Journal of Sciences· 0 citations
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