Occurrence, Health Risk and Source Apportionment of Polycyclic Aromatic Hydrocarbons in Borehole Water Around Fuel Stations in Owerri West Local Government Area, Imo State, Nigeria
Aug 2026· INTERNATIONAL JOURNAL OF CHEMISTRY AND CHEMICAL PROCESSES· 0 citations
Abstract
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.
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.
Peter Mamuro Eguvbe, Solomon Erhajemu Ogoron, E. W. Odali et al.· Sriwijaya Journal of Environ...· 0 citations
Heavy metal contamination in recreational soils may present environmental and public health concerns, particularly in areas exposed to traffic, commercial activities, and other anthropogenic inputs. This study assessed the concentrations, pollution status, ecological risk, and human health risks associated with selected heavy metals in playground soil collected from Filin Police Station, Batagarawa Local Government Area, Katsina State, Nigeria. Topsoil samples were collected from three locations at a depth of 0–10 cm using a systematic sampling approach. Heavy metal concentrations were determined using atomic absorption spectrophotometry after sample preparation and acid digestion. The results were used to estimate the geo-accumulation index, enrichment factor, contamination factor, pollution load index, potential ecological risk index, target hazard quotient, hazard index, and incremental lifetime cancer risk. Iron (1.42 ± 0.0201 mg/kg), manganese (1.34 ± 0.0045 mg/kg), and chromium (1.27 ± 0.0125 mg/kg) had the highest measured concentrations, while cadmium (0.09 ± 0.0010 mg/kg) and copper (0.04 ± 0.0048 mg/kg) occurred at the lowest levels. The geo-accumulation index, contamination factor, pollution load index, and potential ecological risk index generally indicated low contamination and low ecological risk. However, enrichment factor values suggested possible anthropogenic influence for chromium, lead, and zinc. Health risk estimates indicated that dermal exposure was the main contributor to non-carcinogenic risk in both children and adults. Chromium, nickel, and cadmium indicated potential carcinogenic concern for children, while lead, chromium, and nickel indicated potential carcinogenic concern for adults.
Abdullahi Nasir, A. Usman, Aliyu Ibrahim Yaradua et al.· Asian Journal of Applied Che...· 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.
The spatial distribution, sources and ecological risk of 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs) in surface soil from Liuxin area, Xuzhou, China was investigated in this study. Gas chromatography-mass spectrometry (GC-MS) analysis revealed ΣPAH concentrations ranging from 115.66 to 373.53 ng∙g-1 (mean: 196.26 ng∙g-1), with phenanthrene (Phe) exhibiting the highest mean concentration (51.18 ng∙g-1). Spatial analysis demonstrated a southeast-to-northwest concentration gradient, with maximum PAH levels observed in southeastern zones. PAH composition showed dominance of low-molecular-weight species (2,3 rings: 46.7 %), followed by 5,6 ring PAHs (28.3 %), and 4-ring compounds (24.9 %). Source apportionment using molecular diagnostic ratios (DR) and positive matrix factorization (PMF) identified four primary contributors: coal-fired power generation & metallurgical emissions (34%), biomass combustion (31%), diesel fuel combustion/leakage (29%), traffic emissions (6%). Ecological risk assessment employing Dutch soil quality standards revealed localized exceedances in southeastern areas, particularly for fluoranthene (Fla) and Phe. However, toxic equivalency quotients (TEQs) remained low, with incremental lifetime cancer risks (ILCRs) below 10-6 for all exposure pathways. These findings indicate that while PAH contamination warrants monitoring, current levels pose negligible carcinogenic risk to the local population.
Jinxian He, Chen-Long Ding, Pei-Lin Sun et al.· Environmental Research Commu...· 0 citations
Polycyclic aromatic hydrocarbons (PAHs) are persistent semi-volatile organic contaminants generated mainly during the incomplete combustion of organic materials and petroleum-derived fuels. This study assessed PAH levels in indoor and outdoor air and estimated the associated inhalation health risks in Akpajo, Alesa and Aleto communities of Eleme Local Government Area, Rivers State, Nigeria, an industrially and traffic-influenced area of the Niger Delta. Twelve 24-hour integrated air-sampling conditions were evaluated across three communities, two seasons (dry and wet) and two microenvironments (indoor and outdoor). Airborne particulate-bound PAHs were collected using a high-volume air-sampling approach, solvent-extracted with dichloromethane:n-hexane (1:1, v/v), concentrated and quantified by gas chromatography-mass spectrometry. Method quality control included internal-standard calibration, field and method blanks, duplicate checks, surrogate recovery assessment, blank correction, and limits of detection and quantification. Statistical analysis was based on descriptive statistics, including range, arithmetic mean, pooled congener totals, community means, seasonal means and indoor-outdoor means. Total PAH concentrations ranged from 7.40 µg/m³ in Alesa wet-season indoor air to 30.55 µg/m³ in Aleto dry-season outdoor air. The mean total PAH concentration was highest in Aleto (21.41 µg/m³), followed by Akpajo (11.80 µg/m³) and Alesa (10.39 µg/m³). Dry-season air had a higher mean total PAH concentration (18.18 µg/m³) than wet-season air (10.88 µg/m³), while outdoor air (15.75 µg/m³) exceeded indoor air (13.32 µg/m³). Anthracene, pyrene, benzo(k)fluoranthene, naphthalene, fluorene and phenanthrene were the dominant contributors to the pooled PAH burden. Non-detected high-molecular-weight PAHs were reported as below the method detection limit rather than as true zero values. Screening-level risk assessment showed that children had higher estimated lifetime average daily dose and incremental lifetime carcinogenic risk than adults under the same sampling conditions. The highest child ILCR occurred in Aleto dry-season outdoor air (4.12E-04), while several child-risk estimates exceeded 1.00E-04, indicating potential concern under the assumptions used. The findings indicate measurable PAH contamination, higher dry-season burden and greater screening-level risk estimates for children. Routine monitoring, emission reduction, dust control and targeted public-health communication are recommended.
O. N. Nwidaa, T. Ideriah, O. Bull et al.· Journal of applied chemical...· 0 citations
Mineral exploitation and energy consumption contribute to significant environmental pollution, threatening ecological stability and human health, especially in large coal mining areas. To evaluate environmental risks in the Yulin coal mining area, a study was carried out on polycyclic aromatic hydrocarbons (PAHs) in a representative river across different seasons. Multivariate statistical analysis and a positive matrix factorization (PMF) model were employed for source identification and quantitative allocation. To assess ecological-health risks linked to PAH concentrations and source orientation, an integrated methodology was applied, combining Monte Carlo simulation (MCS), PMF, and risk assessment models. Among all PAHs, BaA, BaP, BbF, InP, and DahA exhibited elevated concentrations, surpassing USEPA threshold values at many sampling sites. Seasonal variations were observed, with ∑PAH concentrations averaging 185.11 and 128.22 ng∙L-1 in the dry and wet seasons, respectively. PAHs in Kuye River were primarily influenced by coking/petroleum, coal combustion, traffic emissions, and fuel-wood burning, contributing 37.39%, 34.78%, 14.40%, and 13.44%, respectively, to total concentrations. Ecological risks associated with these source-specific PAHs were classified as moderate, mainly attributed to BaA derived from coal combustion sources. Non-carcinogenic risks for all population groups were within safe limits based on the USEPA hazard quotient threshold. In contrast, under conservative exposure assumptions, the average total carcinogenic risks for all six population groups associated with source-specific PAHs exceeded the USEPA acceptable risk level, with a relatively high probability of risk exceedance. Females aged 2 -15 years showed the highest estimated risks, and dermal exposure was estimated as the primary pathway. In addition, traffic emission sources and BaP were inferred as potential priorities for controlling carcinogenic risks. These results are screening-level estimates based on default parameters and require validation using local data. The findings highlight the importance of probabilistic risk assessment methods based on specific pollution sources and provide a scientific basis for comprehensive PAH risk assessment and prevention strategies in coal mining areas.
Ying Dong, Xinlin He, Ya-ning Zhang et al.· Ecotoxicology and Environmen...· 0 citations
