Distribution, source and ecological risk assessment of polycyclic aromatic hydrocarbons in cultivated land of Liuxin area, Xuzhou, China

Polycyclic aromatic hydrocarbons in surface sediments of Pinghai Bay, a subtropical semi-enclosed embayment in China: Distribution, source apportionment, and ecological risk assessment.

This study investigated the occurrence, spatial distribution, source apportionment, and ecological risk of 16 priority polycyclic aromatic hydrocarbons (PAHs) in surface sediments of Pinghai Bay, a typical subtropical semi-enclosed bay in Fujian, China, is increasingly subjected to anthropogenic pressures from intensive aquaculture, offshore wind farm activities, and coastal urban development. However, systematic data on the occurrence, sources, and ecological risks of PAHs in its surface sediments remain scarce, hampering effective environmental management. Twenty-five sediment samples were collected in November 2024 and analyzed using gas chromatography-mass spectrometry (GC-MS). Total PAH concentrations ranged from 20.6 to 206.2 ng/g dw (mean 70.4 ng/g dw), indicating a low overall contamination level. PAHs exhibited a distinct nearshore-high, offshore-low distribution pattern, with the high-concentration zone (stations P01-P06, > 100 ng/g dw) primarily associated with intensive coastal human activities including domestic coal combustion in coastal villages, small fishing vessel operations, and agricultural runoff from terrestrial streams flowing into the bay. Three-ring PAHs were the most abundant (45.58%), implying mixed sources from petroleum release and combustion processes. PAH concentrations were moderately and significantly positively correlated with TOC (R2 = 0.43, p < 0.01). Integrated ecological risk assessment based on Effects Range-Low/Effects Range-Median, Mean Effects Range-Median Quotient, Toxic Equivalents and Risk Quotient consistently indicated low ecological risk across the study area, with marginally elevated risk in nearshore zones. These results provide valuable baseline data for pollution control and environmental management of subtropical small- to medium-sized semi-enclosed bays.

Soil polycyclic aromatic hydrocarbons in energy chemical industrial plants of Northwest China: Sources and health risk implications from a field-based study.

Polycyclic aromatic hydrocarbons (PAHs) in soils of energy chemical industrial plants pose considerable ecological and health risks. However, comprehensive studies between petrochemical and coal chemical plants in arid Northwest China remain limited. In this study, 75 surface soil samples (0-20 cm) were collected from 15 large-scale plants (four petrochemical and 11 coal chemical plants) across the region. Sixteen priority PAHs (∑PAHs) were quantified, and source apportionment was conducted using diagnostic ratios and principal component analysis-multiple linear regression (PCA-MLR). In addition, health risks were evaluated using toxic equivalence factors and incremental lifetime cancer risk (ILCR) models. Results showed a stark contrast in PAHs concentrations, with coal chemical plants averaging 4652.2 ng/g and reaching up to 188,506.0 ng/g at a coal tar processing site, compared to 225.6 ng/g in petrochemical plants. Four-ring PAHs were predominant, accounting for 64.5% and 52.1% of total PAHs in coal chemical and petrochemical soils, respectively, indicative of high-temperature combustion sources. PCA-MLR analysis identified coal combustion as the dominant source at coal chemical sites (96.5%), while petrochemical sites exhibited mixed sources, including oil leakage (49.6%) and vehicular emissions (25.6%). Health risk assessment revealed that ILCR values exceeded the US EPA threshold of 10-6 at seven sampling points in coal chemical plants, with the highest risk observed at site BXT-2 (1.99 × 10-4), primarily driven by dermal and oral exposure to benzo[a]pyrene. These findings highlight the urgent need for stricter control of high-temperature industrial processes and improved management of hazardous waste in energy chemical industrial plants.

Polycyclic Aromatic Hydrocarbon (PAHs) Pollution Status of Soil, Water, and Edible Vegetables Within Cashew Nut Processing Clusters in Enugu, Nigeria

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.

Distribution, sources, and risk assessment of polycyclic aromatic hydrocarbons in riparian soils along a transect of the Liuxi River, South China

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.

Environmental and Spatial Analysis of Soil Contamination by Polycyclic Aromatic Hydrocarbons (PAHs) Near Maysan Refinery Using GIS Techniques, Southern Iraq

This study aimed to determine and evaluate the distribution and concentration of polycyclic aromatic hydrocarbons (PAHs), total organic carbon (TOC), pH, and electrical conductivity (EC) in selected industrial soils from several facilities within the Maysan Refinery and in soils collected from urban areas surrounding the refinery in southern Iraq. Ten soil samples were collected from a depth of 15 cm. PAH concentrations were determined using GC–MS analysis, while extraction was performed using a Soxhlet apparatus. TOC values were calculated according to the Walkley and Black method. The analyses showed variations in the concentrations of hydrocarbon compounds among the samples. The highest concentration of PAHs was recorded inside the Maysan Refinery, particularly in Sample 3 collected near the oil tanks, where the total concentration reached 10.73093 ppm. This high concentration of aromatic compounds was attributed to the presence of carcinogenic aromatic hydrocarbons, especially Acenaphthylene, which showed a significant concentration of 4.2959 ppm, indicating potential environmental contamination in the refinery soils. In contrast, the lowest total concentration of aromatic compounds was approximately 0.004911 ppm in Sample 7, collected near the refinery garage. Chemical analyses revealed that TOC concentrations varied among the samples. The highest TOC value was recorded near the oil pumps at approximately 8.59%, whereas the lowest value was observed in agricultural land outside the refinery at approximately 1.09%. These variations were attributed to differences in pollutant distribution and the locations of oil spills. In general, the highest pollutant levels were recorded near the oil tanks, and soil type had a significant effect on the distribution of hydrocarbon concentrations. These hydrocarbons contained carcinogenic pollutants such as Acenaphthylene, whereas the agricultural soils were free from such contaminants.