Source-oriented probabilistic risk assessment of polycyclic aromatic hydrocarbons in coal-mining streams: Coupling Monte Carlo simulation, positive matrix factorization, and risk models.

Soil heavy metals in a typical coal mining cluster of Northern China: Pollution, source apportionment, and eco-health risks

Summary Coal mining activities can alter soil heavy-metal accumulation and risk patterns. To identify pollution characteristics, sources, and ecological and health risks, 88 surface soil samples from Tongchuan Town, Ordos City, were analyzed using enrichment factor, potential ecological risk index, positive matrix factorization, soil physicochemical analysis, and Monte Carlo-based health risk assessment. Heavy-metal concentrations were generally low and regional pollution risk was controllable, although Cd exceeded the agricultural soil risk screening value at some sites. Cd and Hg showed local enrichment and dominated ecological risk, with over 60% of sites at moderate or higher risk. Industrial-traffic sources contributed the most (44.09%), followed by natural sources (34.06%), coal-related emission-atmospheric deposition (16.35%), and mining disturbance-agricultural inputs (5.50%). Soils were strongly alkaline, with low organic matter and nitrogen and potassium deficiencies. Health risks were acceptable; oral ingestion was dominant, Cr and As were key contributors, and children were more sensitive.

Linking cadmium source uncertainty to crop accumulation and health risk in mining-impacted agricultural soils using Cd isotopes and receptor modelling

Distribution, source and ecological risk assessment of Polycyclic Aromatic Hydrocarbons in cultivated land of Liuxin Area, Xuzhou, China

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.

Soil Quality, Pollution Indices and Health Risk of Metals and PAHs at a Crude-Oil Spill Site in Okpohovor, Delta State, Nigeria

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.

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

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.

From risk to response: Causal effects of soil heavy metal ecological risk on microbial community assembly in mining area.

Accurate ecological risk assessment is essential for pollution prevention and risk control of heavy metals (HMs) in mining areas. Herein, a hierarchical ecological risk assessment framework integrating source apportionment, risk characterization, and bacterial community analysis was proposed, and causal pathways between HM risk and bacterial diversity was established using Mantel analysis and structural equation modeling. Source apportionment revealed As, Cd, Cu, Pb and Zn in industrial land and nearby agricultural soils were primarily influenced by mining activities, whereas those in distant agricultural soils were governed by agricultural and mining activities. Unlike traditional indices, site-specific risk quotient provided more realistic ecological risks. The potentially affected fractions (PAFs) for As, Cd, Cu, Pb, and Zn were 25.44%, 2.42%, 39.76%, 13.42%, and 18.06%, respectively, while multi-substance PAF (msPAF) for HMs ranged from 27.34% to 98.98%. The distributions of both PAF and msPAF decreased outward from mining area, exhibiting a concentric circular pattern. Chloroflexota was the most dominant phylum, followed by Pseudomonadota, Bacillota, Actinomycetota, and Acidobacteriota. Causal inference revealed that indirect soil degradation contributed more to alterations in bacterial α-diversity compared with direct effects of msPAF-based risks. Collectively, these findings provide an effective hierarchical risk assessment methodology applicable to similar mining areas.