Search Results (1,629)

Polycyclic aromatic hydrocarbons (PAHs) play a central role in materials science due to their extended π-conjugated systems, with their stability and reactivity depending critically on their aromatic character. In this work, we systematically investigated the aromaticity and stability of a broad range of linear (acenes, phenacenes, biphenylenes, and cyclobuta-acenes) and belt-like (cyclacenes, cyclophenacenes, and cyclobiphenylenes) PAHs containing five to twelve benzene rings. A diverse set of aromaticity descriptors was employed, including geometric (HOMA), electronic (MCI, FLU) and magnetic (NICS) descriptors, plus the recently developed Q₂ indices, based on the components of the distributed multipole analysis (DMA) electric quadrupole tensor. These data were complemented by stability analyses using singlet–triplet energy splitting (ΔE_S–T) and fractional occupation number-weighted densities (N_FOD) values. Our results indicate that acenes and phenacenes follow a comparable aromatic trend, with inner rings possessing lower aromaticity and the edge rings showing a more pronounced aromatic character. A subtle difference is observed in the position of the most aromatic ring, which lies slightly closer to the interior in acenes. Phenacenes, however, exhibit greater overall stability, attributed to their armchair edges. For biphenylenes and cyclobuta-acenes, the antiaromatic cyclobutadiene moiety perturbs the aromaticity only in its direct neighborhood and preserves the aromaticity in the remaining chains. In belt-like systems, cyclacenes exhibit strong radical character and low stability, consistent with longstanding synthetic challenges, whereas cyclophenacenes display enhanced aromaticity and stability with extending size. Cyclobiphenylenes combine localized antiaromatic centers with preserved benzene-like aromaticity in rings distant from the cyclobutadiene unit. Full article

This study explored the potential of bacterial consortia to remediate real diesel-contaminated agricultural soils. Two consortia were tested: a native consortium isolated from contaminated soil and an exogenous consortium derived from vermicompost. Bacterial communities (consortia and soils) were characterized through high-throughput sequencing. Within 30 days, total petroleum hydrocarbons (TPH) were removed most efficiently by bioaugmentation with the native consortium (53.32%), followed by the exogenous vermicompost consortium (47.14%) and the indigenous microbiota (42.52%). Gas chromatography confirmed the reduction of polycyclic aromatic hydrocarbons (PAHs) with 2–5 rings; however, terphenyl, chrysene, and pyrene persisted. The highest TPH biodegradation rate was observed in the treatment inoculated with the native consortium (208.5 mg/kg per day), followed by the treatment with indigenous microbiota (181.8 mg/kg per day) and the exogenous consortium (161.9 mg/kg per day). Furthermore, hydrocarbon-degrading bacterial populations increased significantly during the first week but declined after day 21, showing a negative correlation with TPH concentrations across all treatments, indicating that the highest bacterial activity and degradation occurred during the first 14 days. Taxonomic analysis identified Actinobacteria as the most abundant phylum in the initial soil, whereas Proteobacteria dominated both the consortia and the bioremediated soils. Significant differences in community structure and composition were observed between the consortia according to their origin, influencing removal efficiency. Dominant genera shifted from Nocardioides and Streptomyces in untreated soil to Pseudomonas, Sphingobium, and Pseudoxanthomonas following biological treatments, while Nocardia, Rhodococcus, and Bacillus remained nearly constant. These findings underscore the effectiveness of adapted bacterial consortia in restoring real diesel-contaminated agricultural soils and highlight potential microbial succession patterns associated with biodegradation and soil ecological recovery. Full article

The novelty lies in combining chemical and ecotoxicological approaches to evaluate the safety of ashes from different fuels. Its practical relevance is in demonstrating that only mixed firewood ash shows sufficiently low toxicity for safe use in home gardens, offering guidance for sustainable household ash management. The use of ash in agriculture as a fertilizer has become a topic which is gaining growing attention because of its high nutrient content and its capacity to enhance soil structure. Ash from the combustion of wood, coal or plant biomass, although at first glance it seems to be a useless residue, contains a large amount of components essential for the healthy development of plants. These include potassium, phosphorus, magnesium, calcium and many microelements that can significantly affect the yield and condition of crops. For this reason, it was deemed necessary to investigate the toxicity of ashes produced during the burning of solid materials. The study material consisted of samples collected under controlled conditions resulting from the burning of the following materials: lumps of hard coal larger than 60 mm, hard coal graded between 25 and 80 mm, fine hard coal ranging from 8 to 25 mm, wood pellets, and a mixture of firewood types. A leaching procedure was then carried out to obtain eluates from the individual ash types. The analyses made it possible to determine and evaluate the extent to which polycyclic aromatic hydrocarbons (PAHs) leach from ashes originating from different fuels. Furthermore, the effect of fuel type on the transfer of these substances into the water environment was established. Carcinogenic equivalents of ash solutions, as well as the acute ecotoxicity of the eluates, were also assessed using Microtox^® biotests with luminescent bacteria Aliivibrio fischeri. Based on the results, it was shown that the eluate derived from the combustion of mixed firewood exhibited the lowest toxicity, both with respect to PAH-related indicators and Microtox^® outcomes. In our view, only this type of ash can be regarded as suitable for agricultural application in home gardens. Full article

As chemical exposures are increasingly emphasised as public health concerns, understanding how people perceive chemical risks is vital for shaping responsive and inclusive human biomonitoring (HBM) programmes. Public awareness not only influences individual behaviours but can also inform national policy priorities and scientific focus. This study reports findings from the Human Biomonitoring for Ireland (HBM4IRE) feasibility study, which conducted a social survey adapted from the HBM4EU framework. The survey assessed awareness and perceived harmfulness of 24 chemical groups among 218 Irish residents, distinguishing between experts (involved in chemical management) and non-experts. Lead, arsenic, mercury, pesticides, tobacco alkaloids, volatile organic compounds (VOCs), solvents, cadmium, polycyclic aromatic hydrocarbons (PAHs), and persistent organic pollutants (POPs) received the highest perceived harmfulness scores. Non-experts reported lower perceived harmfulness for substances such as phthalates, parabens, and Per- and polyfluoroalkyl substances (PFASs), indicating significant awareness gaps. These findings demonstrate convergence between public and expert views for well-recognised substances but also highlight gaps for certain emerging chemicals. This study highlights the importance of targeted, country-specific education campaigns and shows the added value of integrating public perceptions into HBM design and priority setting. Full article

Polycyclic aromatic hydrocarbons (PAHs) are toxic pollutants produced by the incomplete combustion of fuels and biomass. They are highly persistent and can accumulate in the food chain. Honey, a natural product susceptible to atmospheric deposition, has recently been recognized as an important bioindicator for monitoring environmental pollution. This systematic review examined 29 articles published from 2000 to 2025 analyzing the global presence, concentrations, and potential health risks of PAHs in honey. Results showed that the sum of polycyclic aromatic hydrocarbons (ΣPAHs) concentrations in honey ranged from below the detection limit to 166.83 µg/kg. Higher levels were observed in urban and industrial areas. Seventeen studies analyzed 16 PAHs prioritized by the US Environmental Protection Agency (EPA), with benzo[a]pyrene (BaP) being the most frequently detected, a highly toxic compound. Although most samples met international food safety standards, levels exceeding European regulatory limits were detected in some areas, raising concerns about local health risks. The results of this study emphasize the need for standardized analytical methods and routine monitoring to more accurately assess the exposure risk of PAHs in honey. Full article

People are exposed to mixtures of metals, per- and polyfluoroalkyl substances (PFAS), phthalates, and polycyclic aromatic hydrocarbons (PAH) rather than single chemicals, yet mixture inference is hampered by high dimensionality, correlation, missingness, and left-censoring below limits of detection (LOD). We analyzed 2013–2014 National Health and Nutrition Examination Survey (NHANES) biomarkers (n = 4367) to (i) recover latent, interpretable co-exposure structures and (ii) quantify how these mixtures relate to liver health. To denoise and handle censoring, we applied Principal Component Pursuit with LOD adjustment (PCP-LOD), decomposing the exposure matrix into a non-negative low-rank component (population co-exposure profiles) and a sparse component (individual spikes), and then used Bayesian Kernel Machine Regression (BKMR) to estimate nonlinear and interactive associations with AST, ALT, GGT, ALP, total bilirubin, and the Fatty Liver Index (FLI), retaining analytes with ≥50% detection. PCP-LOD revealed coherent clusters (e.g., long-chain PFAS grouping; shared metal loadings), while the sparse layer highlighted episodic phthalate elevations. BKMR indicated outcome-specific mixture effects: PAHs and selected phthalates showed consistently positive associations with ALP, GGT, and FLI; PFAS (PFOS, PFNA, PFOA) exhibited modest associations with ALP and bilirubin; metals displayed mixed directions. A joint increase in the overall mixture from the 25th to 75th percentile corresponded to an upward shift in FLI and a smaller rise in ALT. This censoring-aware low-rank-plus-sparse framework coupled with flexible mixture modeling recovers actionable exposure architecture and reveals clinically relevant links to liver injury and steatosis, motivating longitudinal and mechanistic studies to strengthen causal interpretation. Full article

This article reviews the research progress of BN-doped polycyclic aromatic hydrocarbons in the field of optoelectronics in recent years. Polycyclic aromatic hydrocarbons and their derivatives have attracted widespread attention in the field of organic optoelectronic materials due to their unique optical and electronic properties and thus are widely used in various fields such as organic light-emitting diodes (OLEDs), field-effect transistors (OFETs), and organic solar cells (OSCs). By introducing boron–nitrogen (BN) units to replace carbon–carbon (C-C) units in the framework of polycyclic aromatic hydrocarbons, the electronic structure and spatial configuration of conjugated molecules can be effectively regulated, thereby optimizing their optoelectronic properties. This article first outlines the structural characteristics of BN-doped polycyclic aromatic hydrocarbons, then explores their synthesis methods and properties, and provides a detailed overview of their applications in the field of optoelectronics. BN-doped polycyclic aromatic hydrocarbons have shown great potential for applications in both optical and electrical fields. Finally, this review points out that although the application of BN-embedded polycyclic aromatic hydrocarbons in optoelectronic devices is still in its early stages, facing difficulties in synthesis and insufficient stability, the rational design of BN to replace polycyclic aromatic hydrocarbons is expected to bring new opportunities for organic electronics and advance the development of this field. Full article

As attention to environmental risks from the PAHs in biochar production increases, developing a low-cost and easy-to-operate optimized pyrolysis process is urgent. The effect of extra biochar was investigated in order to minimize polycyclic aromatic hydrocarbons (PAHs) on biochar and residual tar for the development of a new fixed-bed pyrolysis process. Hence, the effect of extra biochar as a catalyst on the reduction effect on PAHs originating from corn stover pyrolysis was inspected and explored in this study. Pyrolysis was conducted at 500, 600, and 700 °C in a tube furnace reactor with corn stover as the biomass feedstock. Biochar prepared at 500 °C, 600 °C, and 700 °C was used as a catalyst by stacking extra biochar on top of the corn stover raw material. Then, the concentration of PAHs in corn stover biochar and residual tar inside the reactor was examined. The physicochemical characteristics, including morphology, pore structure, and chemical structures of extra biochar, were investigated separately. The results showed that, with stacking extra biochar, the concentrations of PAHs in corn stover biochar (7.15 mg/kg to 1.25 mg/kg) and residual tar (132.23 mg/kg to 101.10 mg/kg) inside the reactor decreased significantly at medium temperatures (500 °C). The concentrations of PAHs in corn stover biochar decreased from 9.14 mg/kg, 10.44 mg/kg to 3.66 mg/kg, 2.7 mg/kg. However, the concentrations of PAHs of residual tar inside the reactor increased significantly at medium temperatures (600 °C, 700 °C). In addition, the reaction mechanism of extra biochar as a catalyst to reduce PAHs in corn stover biochar was established. The results suggest that the measure of adding extra biochar reduced PAHs in resulting biochar effectively, but is not high enough to eliminate PAHs issues in the entire pyrolysis process completely. Full article

The Black Sea is a semi-enclosed basin subject to intense anthropogenic pressures and transboundary pollution, making reliable and comparable monitoring data essential for large-scale environmental assessments. However, national practices differ considerably, hindering data integration and coordinated reporting under international frameworks. This study, conducted within the Horizon 2020 project “Advancing Black Sea Research and Innovation to Co-develop Blue Growth within Resilient Ecosystems” (BRIDGE-BS), evaluated pollutant surveillance methodologies with a focus on heavy metals and priority organic contaminants (polycyclic aromatic hydrocarbons, polychlorinated biphenyls, organochlorine pesticides). Standard Operating Procedures (SOPs) were collected from institutions across Black Sea countries and systematically compared for water, sediment, and biota matrices. The analysis revealed shared reliance on internationally recognized techniques but also heterogeneity in sediment fraction selection, digestion and extraction conditions, instrumental approaches, and quality assurance/quality control (QA/QC) documentation. To complement this assessment, an intercalibration (IC) exercise was organized through the QUASIMEME proficiency testing scheme, accompanied by a follow-up structured questionnaire sent to participant institutions. While individual results remain confidential, collective feedback highlighted common challenges in calibration, blank correction, certified reference materials (CRMs) availability, digestion variability, instrument maintenance, and the reporting of uncertainty and detection limits. Together, these findings confirm that harmonization in the Black Sea requires not only improved comparability of laboratory methods but also the future alignment of assessment methodologies, including indicators and thresholds, to support coherent, basin-wide environmental evaluations under regional conventions and EU directives. Full article

This study investigates the viability of industrial hempseed oil as a sustainable extender oil in rubber compounding, addressing the urgent demand for alternatives to petroleum-based oils due to regulatory pressures on polycyclic aromatic hydrocarbons (PAH). We employed automated neural networks to analyze the physical and mechanical properties of rubber composites containing industrial hempseed oil, comparing them with six vegetable oils and three petroleum-based oils at extender oil concentrations from 0 to 30 phr. The results revealed that compounds with 20 phr of industrial hempseed oil and raw soybean oil exhibited the highest cure rate index values of 64.32 1/min. Rubber samples with industrial hempseed oil showed a significant 18% reduction in hardness compared to conventional oils, with the softest rubber measuring 40.5 Shore A hardness at 30 phr. Additionally, energy consumption during mixing was decreased by up to 12% for vegetable oil samples compared to mineral oils, enhancing processing efficiency. The neural network approach yielded more accurate predictions of the cure rate index, Shore A hardness, and power consumption during rubber mixing, with a validation performance exceeding 99.2%. Sensitivity analysis identified key factors, including oil content and surface tension, influencing rubber hardness. Overall, this study underscores the potential of industrial hempseed oil as an effective, eco-friendly substitute for conventional mineral oils, contributing to more sustainable practices in the rubber industry. Full article

This study examines the impact of an unintended fire at the Drava International plastic processing facility near Osijek, Croatia, on soil quality and the potential human health risks associated with agricultural soils within a 10 and 20 km radius. Surface soil samples (0–5 cm) were collected from ten locations within 10 km three days after the incident, and eight composite samples were taken from sites 10–20 km away 17 days’ post-event. Additionally, 18 control samples previously collected for soil fertility or quality monitoring were included for comparative analysis. In total, 36 agricultural soil samples were analyzed for pH, organic matter, total phosphorus, potassium, calcium, magnesium, and trace elements (Cr, Co, Ni, Cu, Zn, As, Pb). Eighteen post-fire samples were also analyzed for polycyclic aromatic hydrocarbons (PAHs), dioxins, and perfluoroalkyl substances (PFAS). Ecological risk was assessed using the pollution load index (PLI) and enrichment factor (EF), while human health risk was evaluated through the estimation of incremental lifetime cancer risk (ILCR) and individual carcinogenic risks (CRi) for As, Cr, Ni, and Pb. Results showed that concentrations of dioxins (TEQ LB and UB), dioxin-like PCBs, and non-dioxin-like PCBs in samples within 10 km were either below detection limits or present in trace amounts (4.0 × 10⁻⁶ mg/kg). PFAS compounds were not detected (<0.0005 mg/kg). The total concentration of non-dioxin-like PCBs ranged from 0.0023 to 0.0047 mg/kg, well below the maximum permissible levels. Post-fire contamination profiles revealed consistently higher PAH concentrations in the 0–10 km zone (mean 0.100 mg/kg) compared to the 10–20 km zone (mean 0.062 mg/kg). Twenty PLI values exceeded the threshold of 1 (range: 1.00–1.26), indicating moderate pollution, while the remaining values (PLI 0.82–0.99) suggested no pollution. EF values indicated minimal to moderate enrichment (EF < 2), supporting the conclusion that metal presence was predominantly geological with limited anthropogenic influence. All ILCR values for adults and children remained below the acceptable threshold of 1 × 10⁻⁴, indicating low carcinogenic risk under both pre- and post-fire conditions. CRi values followed a consistent decreasing trend across exposure pathways: ingestion > dermal absorption > inhalation. Full article

The excessive use of chemical fertilizers results in environmental issues, including loss of soil fertility, eutrophication, increased soil acidity, alterations in soil characteristics, and disrupted plant–microbe symbiosis. Here, we synthesize recent studies available from up to 2025, focusing on engineered biochar and its application in addressing issues of soil nutrient imbalance, soil pollution from inorganic and organic pollutants, soil acidification, salinity, and greenhouse gas emissions from fields. Application of engineered biochar enhanced the removal of Cr (VI), Cd²⁺, Ni²⁺, Zn²⁺, Hg²⁺, and Eu³⁺ by 85%, 73%, 57.2%, 12.7%, 99.3%, and 99.2%, respectively, while Cu²⁺ and V⁵⁺ removal increased by 4 and 39.9 times. Adsorption capacities for Sb⁵⁺, Tl⁺, and F⁻ were 237.53, 1123, and 83.05 mg g⁻¹, respectively, and the optimal proportion of polycyclic aromatic hydrocarbon (PAH) removal was 57%. Herbicides such as imazapyr were reduced by 23% and 78%. Low-temperature pyrolyzed biochar showed high cation exchange capacity (CEC) resulting from improved surface functional groups. Although biochar application led to a yield increase of 43.3%, the biochar–compost mix enhanced it by 155%. The analysis demonstrates the need for future studies on the cost-effectiveness of biochar post-processing, large-scale biochar aging studies, re-application impact, and studies on biochar–compost or biochar–fertilizer mix productivity. Full article

In this study, four polycyclic aromatic hydrocarbons (4PAHs: benz[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene (BaP)) were quantified in 110 herb and spice products marketed in South Korea. A validated gas chromatography–mass spectrometry (GC-MS) method achieved high sensitivity with limits of detection (LOD) ranging from 0.08 to 0.18 µg/kg and limits of quantification (LOQ) ranging from 0.24 to 0.55 µg/kg, with recoveries consistent with the Association of Official Analytical Chemists guidelines. Among the tested items, oregano contained the highest BaP concentrations with 7.13 µg/kg, while overall concentrations of the sum of 4PAHs remained below European Union limits. The BaP-based toxic equivalent (TEQ_BaP) and the toxic equivalent for the sum of 4PAHs (TEQ_Σ4PAHs) were 7.13 and 7.50 µg/kg, respectively, with oregano showing the highest values. Risk assessment using the margin of exposure (MOE) showed all values exceeded 10⁶, indicating negligible health concern. These findings provide a basis for continuous monitoring and regulatory management of PAHs in herbs and spices. Full article

Bottom sediments play a central role in regulating contaminant dynamics in aquatic systems. They act as both storage sites and reactive zones where contaminants undergo transformation, sequestration, or remobilization. Contaminants primarily enter sediments through anthropogenic activities, including agricultural runoff, industrial effluents, wastewater discharge, urban runoff, and mining operations. This review focuses on six major contaminant groups, including nutrients, heavy metals, pharmaceutical residues, pesticides, polycyclic aromatic hydrocarbons, and microplastics, and examines the mechanistic processes that govern their fate in sediments. The main mechanisms includesorption–desorption on minerals and organic materials, sedimentation, and redox processes that regulate metal immobilization and sulfide formation. The persistence and mobility of contaminants are also influenced by synergistic or antagonistic interactions among pollutants, microbial transformation of organic compounds, and oxidative degradation of microplastics by reactive oxygen species. Contaminants can affect benthic communities by causing toxic effects and oxygen depletion. They also may alter microbial and macrofaunal populations and contribute to bioaccumulation and biomagnification. Ultimately, these insights are important for predicting contaminant behavior and assessing ecological risks, which directly informs the development of effective environmental monitoring programs and sustainable sediment remediation strategies for the long-term protection of aquatic ecosystems. Full article

While many studies on the health effects of PM_2.5 exist, the risks of PM_2.5 species remain largely unexplored in Middle Eastern and North African countries. This study assesses, for the first time, the carcinogenic and non-carcinogenic health risks for elements, polycyclic aromatic hydrocarbons (PAHs), phthalates, polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs) bound to PM_2.5 in the Greater Cairo Area. A total of 59 samples were collected from an urban site in Dokki (November 2019–January 2020). Chemical analysis showed higher concentrations of PCDFs (5418 fg/m³) than PCDDs (1469 fg/m³), with DL-PCBs being the most abundant (6577 fg/m³). Health risk assessment for inhalation showed non-carcinogenic risks for all age groups, especially for newborns. Manganese (Mn) and lead (Pb) posed the highest elemental non-carcinogenic risk, while the hazard quotient (HQ) for PAHs exceeded 1 across all ages. PCDDs, PCDFs, and DL-PCBs showed an estimated cancer risk reaching 10⁻⁶ in adults, indicating a significant health concern. Key contributors to cancer risk included arsenic (As), chromium (Cr(VI)), and vanadium (V), which accounted for over 80% of the total elemental cancer risk. Major and trace elements posed the highest lifetime cancer risk, nearly 37 times the acceptable level. Full article