Review on characteristics of PAHs in atmosphere, anthropogenic sources and control technologies

Enrichment and detection of polycyclic aromatic hydrocarbon in tea and coffee using phenyl-functionalized NiFe2O4@Ti3C2TX based magnetic solid-phase extraction

Polycyclic aromatic hydrocarbons (PAHs) are commonly found in various environmental matrices and have received significant attention due to their toxic effects on ecosystems and environmental health. In this study, a specific magnetic composite material derived from MXene, known as phenyl-functionalized NiFe2O4@Ti3C2TX, was designed and synthesized using a simple method. This composite material was used to develop an effective magnetic solid-phase extraction (MSPE) method for enriching trace polycyclic aromatic hydrocarbons (PAHs) in tea and coffee samples. The eluted PAHs were analyzed via gas chromatography-tandem mass spectrometry. Under optimal conditions, this method exhibited excellent linear relationships for 16 PAHs within the ranges of 0.001-25 and 0.0005-25 μg/L, with correlation coefficients exceeding 0.9979. The limits of detection for the target PAHs ranged from 0.1 to 0.3 ng/L. The effectiveness of the proposed method was evaluated by analyzing tea and coffee samples, and the satisfactory spiked recoveries of PAHs ranged from 84.5% to 112.6%.

Removal of benzo[a]pyrene from the soil by adsorption coupled with degradation on saponin-modified bentonite immobilized crude enzymes

Bentonite is a non-metallic mineral with montmorillonite as the main component. It is an environmentally friendly mineral material with large reserves, wide distribution, and low price. Bentonite can be easily modified organically using the surfactant saponin to obtain saponin-modified bentonite (Sap-BT). This study investigates the immobilization of crude enzymes obtained from Trametes versicolor by physical adsorption with Sap-BT. Thus, saponin-modified bentonite immobilized crude enzymes (CE-Sap-BT) were developed to remove benzo[a]pyrene. Immobilization improves the stability of free enzymes. CE-Sap-BT can maintain more than 80% of activity at 45 °C and after storage for 15 d. Additionally, CE-Sap-BT exhibited a high removal rate of benzo[a]pyrene in soil, with 65.69% after 7 d in highly contaminated allotment soil and 52.90% after 6 d in actual soil contaminated with a low concentration of benzo[a]pyrene at a very low laccase dosage (0.1 U/3 g soil). The high catalytic and removal performance of CE-Sap-BT in contaminated sites showed more excellent practical application value.

Distribution characteristics, source analysis and ecological risk assessment of polycyclic aromatic hydrocarbons in surface sediments from the western Honghai Bay of China

The distribution characteristics and risk levels of PAHs in surface sediment in the Honghai Bay of China are studied in this paper. The results showed that the concentration of total PAHs in this area ranged from 100.65 ng·g-1 to 241.31 ng·g-1, with an average concentration of 158.83 ng·g-1. The tricyclic PAHs were the main components in the detected PAHs. PAH pollution levels in this region were low and moderate as compared with adjacent areas. Traceability results showed that the sediment PAHs mainly originate from coal and biomass combustion. PAHs concentrations at some stations were above the Environmental Quality Reference Level. The PAHs toxicity and ecological risk level in surface sediments in the area was determined to be low to moderate by toxicity equivalence testing and risk entropy value assessment.

Dissolved PAHs in the Beibu Gulf and adjacent waters of the South China Sea: Physical and biochemical processes-driven distributional variations

Polycyclic aromatic hydrocarbons (PAHs) in semi-enclosed gulfs are influenced by physical and biochemical processes, which haven't been well understood. This study aims to investigate the spatial distribution and vertical profiles of dissolved PAHs in the Beibu Gulf (BG) and adjacent waters of the South China Sea, along with hydrological, meteorological, and biochemical variables. Particularly relevant are the effects of atmospheric pressure, salinity, ammonium, chlorophyll-a, as well as riverine inputs (RI), sea currents, and upwelling. In surface seawater, the total concentrations of eight dissolved PAHs (∑8PAHs) were 7.76 ± 2.16 ng/L, with a distribution pattern of western Guangdong waters (WGWs) > BG > Qiongzhou Strait (QS). ∑8PAHs in the northern BG (9.10 ± 2.00 ng/L) was significantly higher than that in the southern BG (6.65 ± 1.54 ng/L) (p < 0.01), suggesting that local anthropogenic activities and unique environmental characteristics significantly influenced PAHs distribution. In water column, PAHs in BG displayed enrichment in surface and bottom but decreased in medium water, while those in WGWs and QS decreased with increasing depth. Source apportionment concluded that PAHs in QS and WGWs were primarily from petroleum sources, and PAHs in BG were mainly from coal combustion. RI, combined with circulation, coastal current, and intrusion of SCS water influenced the surface PAHs distribution in BG, with eddy impacts observed. Specifically, regarding the surface PAHs distribution, differences in atmospheric pressure may influence the air-sea exchange of PAHs, especially positively affecting 4-ring PAHs. Salinity factors further corroborated the contribution of RI to 3-ring PAHs, followed by the regulation of PAHs through biological pumps (ammonia and chlorophyll-a). Moreover, upwelling-induced biodegradation and resuspension affected the vertical distribution of PAHs. While most PAHs posed a negligible risk, coking-generated fluorene posed a moderate risk to ecosystems due to changes in the energy structure, warranting further investigation into its toxicological impacts.

Spatiotemporal variations of PM2.5 organic molecular markers in five central cities of the Yangtze River Delta, East China in autumn and winter: Implications for regional and local sources of organic aerosols

Information on the spatiotemporal variations in the composition and sources of organic aerosols (OA) is needed to identify regional influences and to establish effective control measures. Here, 23-h PM2.5 samples were collected in five central cities of the Yangtze River Delta in eastern China, including Nanjing, Suzhou, Wuxi, Changzhou, and Zhenjiang, every three days from 2020/09/01 to 2021/02/28. Each sample was analyzed for water-soluble inorganic ions, organic carbon (OC), elemental carbon (EC), and organic molecular markers (OMMs). Generally, the major components of PM2.5, including NH4+, SO42-, NO3-, OC, and EC, exhibited similar temporal patterns across the five cities. In all OMM groups, the concentrations of PAHs, oxygenated PAHs, and secondary products of isoprene showed strong correlations (r = 0.79±0.050 - 0.93±0.028) and low coefficient of divergence (COD = 0.22±0.024 - 0.30±0.033) between sampling sites, indicating a homogeneous spatial distribution of industrial emissions and biogenic secondary OA in autumn and winter. Other OMMs showed wider r (e.g., steranes and hopanes, 0.20 - 0.80) and COD (0.26 - 0.69) ranges for all site pairs, probably due to the influence of local emissions. Based on the source apportionment results using Positive matrix factorization, the biomass burning factor dominated the contribution to OC and EC in winter and showed strong correlations (r = 0.84±0.063) between the sampling sites, indicating regional transport of emissions from biomass burning and fossil fuel combustion in the heating season. Traffic-related factors had the greatest spatial heterogeneity (r = 0.27±0.19 - 0.51±0.16) and contributed significantly to OC at their maximum levels.

A mechanistic study on the interaction effects between legacy and pollutants of emerging concern: A case study with B[a]P and diclofenac

To study the intricate toxicological mechanisms triggered by exposure to mixed pollutants, we exposed zebrafish embryos to legacy and emerging pollutants through binary mixtures of benzo[a]pyrene (B[a]P) and diclofenac (DFC). The combination of next-generation transcriptomics and toxicopathology disclosed instances where exposure to mixtures did not attain the expected sum of acute effects of individual toxicants, indicating potential antagonism. Despite overall higher mortality in DFC treatments, the same antagonistic trend was noted in genotoxicity and molecular pathways related to RNA turnover, cell proliferation, apoptosis and cell-cycle control. The formation of oedemas in the heart cavity and yolk sac can be an adverse outcome (AO) resulting from exposure to DFC isolated or combined, whose potential key events (KEs) may involve cell cycle arrest and apoptosis via p53 and MAPK pathways. From the findings it can be hypothesised that, rather than genotoxicity, the molecular initiating event (MIE) maybe inflammation triggered by oxidative stress. Nonetheless, the exact role of ROS in the process needs further clarification. Impaired eye function by action of DFC and B[a]P combined may be another AO, in the case caused by ocular degeneration following the suppression of biologic processes and molecular functions involved in eye development and its functionalities, possibly linked to hindered regulation of the expression of hsf4 and cryaa. Altogether, toxicopathology suggests predominance of antagonistic effects, but its integration with mechanism suggests that interactions between DFC and B[a]P in environmentally-relevant concentrations that may lead to hindrance of key functions such as the control of inflammation and cell cycle. These outcomes suggest potentially severe implications for health and survival, in case of prolonged chronic exposure to combined toxicants.

Archetypes of Spatial Concentration Variability of Organic Contaminants in the Atmosphere: Implications for Identifying Sources and Mapping the Gaseous Outdoor Inhalation Exposome

Whereas inhalation exposure to organic contaminants can negatively impact human health, knowledge of their spatial variability in the ambient atmosphere remains limited. We analyzed the extracts of passive air samplers deployed at 119 unique sites in Southern Canada between 2019 and 2022 for 353 organic vapors. Hierarchical clustering of the obtained data set revealed four archetypes of spatial concentration variability in the outdoor atmosphere, which are indicative of common sources and similar atmospheric dispersion behavior. "Point Source" signatures are characterized by elevated concentration in the vicinity of major release locations. A "Population" signature applies to compounds whose air concentrations are highly correlated with population density, and is associated with emissions from consumer products. The "Water Source" signature applies to substances with elevated levels in the vicinity of water bodies from which they evaporate. Another group of compounds displays a "Uniform" signature, indicative of a lack of major sources within the study area. We illustrate how such a data set, and the derived spatial patterns, can be applied to support the identification of sources, the quantification of atmospheric emissions, the modeling of air quality, and the investigation of potential inequities in inhalation exposure.

Decontamination promotes the release of incorporated organic contaminants in hair: Novel insights into non-invasive biomonitoring

Human hair is increasingly employed as a non-invasive biomonitoring matrix for exposure to organic contaminants (OCs). Decontamination procedures are generally needed to remove external contamination from hair prior to analysis of OCs. Despite various existing decontamination protocols, their impacts on internally incorporated (endogenous) OCs in hair remain poorly understood. This study aims to quantitatively assess the impact of decontamination procedures on endogenous OCs in hair, and investigate optimal decontamination processes and factors influencing the removal of endogenous OCs. In this study, guinea pig was exposed to 6 OCs (triphenyl phosphate (TPHP), tris(1,3-dichloro-2-propyl) phosphate (TDCPP), and tri-n-butyl phosphate (TNBP), bisphenol A (BPA), perfluorooctanoic acid (PFOA), and phenanthrene (PHE)), and 6 decontamination procedures with different solvents (methanol, n-hexane, acetone, ultrapure water, Triton X-100, and sodium dodecyl sulfate) were used to rinse exposed guinea pig hair. All OCs and three metabolites (diphenyl phosphate (DPHP), dibutyl phosphate (DBP), and bis(1,3-dichloro-2-propyl) phosphate (BDCPP)) were detected in the majority of washing solutions. The decontamination procedures apparently resulted in the release of endogenous OCs from hair. The percentages of residual OCs in hair exhibited a linear or exponential decrease with more washing cycles. Furthermore, the residuals of OCs in hair washed with organic and aqueous solvents showed negative correlations with molecular weight, polarizability, and their initial concentrations. Although these findings need to be validated with a broader range of OCs, the results obtained in this study provide compelling evidence that current hair decontamination procedures have significant impacts on the analysis of endogenous OCs in hair. Therefore, it is important to interpret quantitative data on hair OC concentrations with caution and to thoroughly consider each decontamination procedure during analysis.

Oxidation of Polycyclic Aromatic Hydrocarbons (PAHs) Triggered by a Photochemical Synergistic Effect between High- and Low-Molecular-Weight PAHs

Photooxidation of polycyclic aromatic hydrocarbons (PAHs), which are widely observed in atmospheric particulate matter (PM), largely determines their atmospheric fate. In the environment, PAHs are highly complex in chemical composition, and a great variety of PAHs tend to co-occur. Despite extensive investigation on the photochemical behavior of individual PAH molecules, the photochemical interaction among these coexisting PAHs is still not well understood. Here, we show that during photooxidation, there is a strong photochemical synergistic effect among PAHs extracted from soot particles. We find that neither small PAHs with low molecular weights of 200-350 Da and 4-8 aromatic rings (named PAHsmall) nor large PAHs with high molecular weights of 350-600 Da and 8-14 aromatic rings (named PAHlarge) undergo photooxidation under red-light irradiation (λ = 648 nm), even though PAHlarge can absorb light with this wavelength. Interestingly, when PAHlarge is mixed with PAHsmall, substantial photooxidation is observed for both PAHlarge and PAHsmall. Comparisons of in situ infrared (IR), high-resolution mass spectrometry, and electron paramagnetic resonance analysis indicate that the presence of PAHsmall inhibits the light quenching effect arising from the π-π stacking of PAHlarge. This leads to the formation of singlet oxygen (1O2), which initiates the photooxidation. Our findings reveal a new mechanism for the photooxidation of PAHs and suggest that complex atmospheric PAHs exhibit distinct photoreactivity from simple systems.

Quantitative analysis of four PAHs in oily sludge by surface-enhanced Raman spectroscopy (SERS) combined with partial least squares regression (PLS) based on a novel nano-silver-silicon coupling substrate

Polycyclic aromatic hydrocarbons (PAHs) present in oily sludge generated by the petroleum and petrochemical industries have emerged as a prominent concern within the realm of environmental conservation. The precise determination of PAHs holds immense significance in both petroleum geochemistry and environmental protection. In this study, a combination of surface-enhanced Raman spectroscopy (SERS) and solid-liquid extraction was employed for the screening of PAHs in oily sludge. Methanol was utilized as the extraction solvent for PAHs, while nanosilver-silicon coupling substrates were employed for their detection. The SERS spectrum was acquired using a portable Raman spectrometer. The nano silver-silicon coupling substrate exhibits excellent uniformity, with relative standard deviations (RSDs) of Phenanthrene, Fluoranthrene, Fluorene and Naphthalene (Phe, Flt, Flu and Nap) being 2.8%, 1.08%, 1.41%, and 5.44% respectively. Moreover, the limits of detection (LODs) achieved remarkable values of 0.542 μg/g, 0.342 μg/g, 0.541 μg/g, and 5.132 μg/g. The quantitative analysis of PAHs in oily sludge was investigated using SERS technology combined with partial least squares (PLS). The optimal PLS calibration model was optimized by combining spectral preprocessing methods and using the SiPLS (Synergy interval partial least squares)-VIP (Variable Importance in Projection) hybrid variable selection strategy. The prediction performance of the D1st (First derivative)-WT (Wavelet transform)-SiPLS-VIP-PLS model was deemed satisfactory, as evidenced by high R2P values of 0.9851, 0.9917, and 0.9925 for Phe, Flt, and Flu respectively; additionally, the corresponding MREP values were found to be 0.0580, 0.0668, and 0.0669 respectively. However, for Nap analysis, the D1st-WT-PLS model proved to be a better calibration model with an R2P value of 0.9864 and an MREP (Mean relative error of prediction) value of 0.0713. In summary, SERS technology combined with PLS based on different spectral pretreatment methods and mixed variable selection strategies is a promising method for quantitative analysis of PAHs in oily sludge, which will provide new ideas and methods for the quantitative analysis of PAHs in oily sludge.

Increasing contamination of polycyclic aromatic hydrocarbons in Chinese soils

China is facing a serious threat PAHs contaminated soil. To better understand the current state of soil PAH pollution in China and contribute to the development of feasible prevention and control measures and policies in the future. This study examines the spatiotemporal distributions of soil Polycyclic Aromatic Hydrocarbons (PAHs) pollution in China since 2000, and investigates the key factors influencing changes in levels of soil PAHs. The results of the survey on soil PAHs concentration levels in 716 areas were analyzed by visualization of ArcGIS pro data, correlation analysis and linear regression analysis, it was found that the increase in soil PAH pollution in China is concerning. The analysis indicates significant regional disparities, with pollution levels in the north being higher than in the south. Over the 20-year period, the median level of PAHs in soil increased by 476.8 μg/kg. Construction land areas that heavily rely on fossil fuels and industrial activities exhibit significantly higher concentrations of polycyclic aromatic hydrocarbons (PAHs) compared to other land use types. The study identifies key socio-economic factors linked to rising PAH levels, including energy consumption (notably coal and oil), industrial and domestic waste production. Coal consumption is highlighted as the leading factor in PAH concentration changes in 18 provinces, followed by industrial waste in 6 provinces. Future projections up to 2030 suggest continued influence of these factors on soil PAH levels. The research emphasizes the urgent necessity for comprehensive soil management policies to address the growing PAH pollution, offering insights into its dynamics and contributing factors in China.

Environmental contamination with polycyclic aromatic hydrocarbons and contribution from biomonitoring studies to the surveillance of global health

This work presents an integrated overview of polycyclic aromatic hydrocarbons' (PAHs) ubiquity comprising environmental contamination in the air, aquatic ecosystems, and soils; characterizes the contamination in biota; and identifies main biomonitors and human exposure to PAHs and associated health risks. Urban centers and industrial areas present increased concentrations in the air (1344.4-12,300 versus 0.03-0.60 ng/m3 in industrial/urban and rural zones) and soils (0.14-1.77 × 106 versus 2.00-9.04 × 103 versus 1.59-5.87 × 103 ng/g in urban, forest, and rural soils), respectively. Increased concentrations were found in coastal zones and superficial waters as well as in sediments (7.00 × 104-1.00 × 109 ng/g). Benzo(a)pyrene, a carcinogenic PAH, was found in all environmental media. Mosses, lichens, tree leaves, bivalves, cephalopods, terrestrials' snails, and honeybees are good biomonitors of biota contamination. More studies are needed to improve characterization of PAHs' levels, distribution, and bioaccumulation in the environmental media and assess the associated risks for biota and human health. Actions and strategies to mitigate and prevent the bioaccumulation of PAHs in the environment and trophic chains toward the WHO's One-Health Perspective to promote the health of all ecosystems and human life are urgently needed.

Chronological evaluation of polycyclic aromatic hydrocarbons in sediments of tangxun lake in central China and impacts of human activities

This study sheds light on the contamination of polycyclic aromatic hydrocarbons (PAHs) in Tangxun Lake sediments, an urban lake reflecting environmental changes in Central China. By analyzing sediment cores from both the inner and outer areas of the lake, we determined the historical trends and sources of PAHs over the past century. The results reveal a significant increase in PAHs concentrations, particularly since the 1980s, coinciding with China's rapid urbanization and industrialization. Using diagnostic ratios and Absolute principal component score-multivariate linear regression (APCS-MLR) methods, we identified petroleum combustion, coal combustion, and biomass combustion as the primary sources of PAHs in the lake sediments. The spatial analysis indicates higher PAHs levels in the inner lake, likely due to its closer proximity to industrial activities. Moreover, by comparing PAH trends in Tangxun Lake with those in other urban, suburban, and remote lakes across China, based on data from 49 sedimentary cores, we highlight the impact of regional socio-economic dynamics on PAH deposition. These insights are crucial for developing effective pollution mitigation strategies and promoting sustainable development in rapidly urbanizing regions.

Migration of fluoranthene, phenanthrene, and pyrene in soil environment during the growth of Brassica rapa subsp. chinensis

The escalating concern surrounding fluoranthene (FLN), phenanthrene (Phe), and pyrene (Pyr), underscores the urgency to investigate their dynamics in the context of agricultural ecosystems. Brassica rapa subsp. chinensis (Bok choy), a globally consumed vegetable, holds particular significance in this scenario. This study explores the migration and transformation of FLN, Phe, and Pyr from soil to Brassica rapa subsp. chinensis during its growth. The germination rates of seeds in these treatments varied, with soil+Bok choy and soil+FLN+Bok choy treatments showing higher rates (77.8 %), while soil+mix+Bok choy exhibited the lowest rate (11.1 %) after 3 days. Analyzing the distribution of FLN, Phe, and Pyr in Brassica rapa subsp. chinensis parts after 30 days revealed a sequence of accumulation in stem> root> leaf. This study provides information on practical implications for regulating the soil-plant migration and transformation of FLN, Phe, and Pyr, offering valuable insights for migration of PAHs pollution in agricultural settings.

A study on source identification of contaminated soil with total petroleum hydrocarbons (aromatic and aliphatic) in the Ahvaz oil field

The oil industry in Khuzestan province (Southwest Iran) is one of the main reasons contributing to the pollution of the environment in this area. TPH, including both aromatic and aliphatic compounds, are important parameters in creating pollution. The present study aimed to investigate the source of soil contamination by TPH in the Ahvaz oil field in 2022. The soil samples were collected from four oil centers (an oil exploitation unit, an oil desalination unit, an oil rig, and a pump oil center). An area outside the oil field was determined as a control area. Ten samples with three replicates were taken from each area according to the standard methods. Aromatic and aliphatic compounds were measured by HPLC and GC methods. The positive matrix factorization (PMF) model and isomeric ratios were used to determine the source apportionment of aromatic compounds in soil samples. The effects range low and effects range median indices were also used to assess the level of ecological risk of petroleum compounds in the soil samples. The results showed that Benzo.b.fluoranthene had the highest concentration with an average of 5667.7 ug/kg in soil samples in the Ahvaz oil field. The highest average was found in samples from the pump oil center area at 7329.48 ug/kg, while the lowest was found in control samples at 1919.4 ug/kg-1. The highest level of aliphatic components was also found in the pump oil center, with a total of 3649 (mg. Kg-1). The results of source apportionment of petroleum compounds in soil samples showed that oil activities accounted for 51.5% of the measured PAHs in soil. 38.3% of other measured compounds had anthropogenic origins, and only 10.1% of these compounds were of biotic origin. The results of the isomeric ratios also indicated the local petroleum and pyrogenic origin of PAH compounds, which is consistent with the PMF results. The analysis of ecological risk indices resulting from the release of PAHs in the environment showed that, except for fluoranthene, other PAHs in the oil exploitation unit area were above the effects range median level (ERM) and at high risk. The results of the study showed that soil pollution by total petroleum hydrocarbons (TPH), both aromatic and aliphatic, is at a high level, and is mainly caused by human activities, particularly oil activities.

Abundance and sources of particulate polycyclic aromatic hydrocarbons and aromatic acids at an urban site in central China

We conducted a simultaneous field study of PM2.5-bound particulate polycyclic aromatic hydrocarbons (PAHs) and aromatic acids (AAs) in a polluted city Zhengzhou to explore the concentration, sources and potential conversion pathways between PAHs and AAs in different seasons. The average concentrations of PM2.5, 28PAHs and 8AAs during the sampling period were 77 µg/m3, 75 ng/m3, and 283 ng/m3, respectively. The concentration of both 28PAHs and 8AAs were highest in winter and lowest in summer with ratios of 6.3 and 2.3, respectively. PAHs with 5-7 rings were the main components of PAHs (52%), followed by 4 rings PAHs (30%) and 2-3 rings PAHs (18%). According to the source appointment results obtained by positive matrix factorization, the main sources of PAHs were combustion and vehicle emissions, which account for 37% and 34%, respectively. 8AAs were divided into three groups, including four benzene dicarboxylic acids (B2CAs), three benzene tricarboxylic acids (B3CAs) and one benzene tetracarboxylic acid (B4CA). And interspecies correlation analysis with PM2.5 source markers were used to investigate potential sources. Phthalic acid (o-Ph) was the most abundant specie of 8AAs (157 ng/m3, 55% of 8AAs), which was well correlated with sulfate. Meanwhile, B3CAs and B4CA were highly correlated with sulfate and weakly correlated with levoglucosan, suggesting that secondary formation was their main source. As logical oxidation products of PAHs, o-Ph and B3CAs showed good correlations with a number of PAHs, indicating possible photochemical oxidation pathway by PAHs. In addition, O3, NO2, temperature and relative humidity have positive effects on the secondary formation of B3CAs.

Indoor air quality in subway microenvironments: Pollutant characteristics, adverse health impacts, and population inequity

Rapidly increasing urbanization in recent decades has elevated the subway as the primary public transportation mode in metropolitan areas. Indoor air quality (IAQ) inside subways is an important factor that influences the health of commuters and subway workers. This review discusses the subway IAQ in different cities worldwide by comparing the sources and abundance of particulate matter (PM2.5 and PM10) in these environments. Factors that affect PM concentration and chemical composition were found to be associated with the subway internal structure, train frequency, passenger volume, and geographical location. Special attention was paid to air pollutants, such as transition metals, volatile/semi-volatile organic compounds (VOCs and SVOCs), and bioaerosols, due to their potential roles in indoor chemistry and causing adverse health impacts. In addition, given that the IAQ of subway systems is a public health issue worldwide, we calculated the Gini coefficient of urban subway exposure via meta-analysis. A value of 0.56 showed a significant inequity among different cities. Developed regions with higher per capita income tend to have higher exposure. By reviewing the current advances and challenges in subway IAQ with a focus on indoor chemistry and health impacts, future research is proposed toward a sustainable urban transportation systems.

Distinct anthropogenic signatures: A comparative analysis of polycyclic aromatic hydrocarbons in sediments from two southeastern Chinese bays

Sansha and Luoyuan Bay are influenced by different industrial structure, but the sources and pollution status of polycyclic aromatic hydrocarbons (PAHs), especially alkylated PAHs, are poorly understood. We studied 25 PAHs in surface sediments from the two bays. The results showed that PAHs concentrations in Sansha and Luoyuan Bay sediment range from 6.54 to 479.28 ng/g and 118.82 to 2984.09 ng/g, respectively. Alkylated PAHs dominated in Sansha (48.86 % of Σ25PAHs), while 3-ring PAHs dominated in Luoyuan (36.32 % of ∑25PAHs). Results of sources analysis indicated oil spills as the main PAHs source in Sansha, and domestic emissions and fossil fuel combustion in Luoyuan. Ecological risk assessment of showed low sediment risk, but in Luoyuan was higher than in Sansha. Compared with Luoyuan Bay, Sansha Bay emits less industrial pollutants, so the pollution is lower than Luoyuan Bay. Increased attention to protecting Luoyuan Bay is recommended.

The modification of surface basicity and its role in naphthalene oxidation: The effect of the basic sites introduced by Ce

A series of V-xCe/Ti catalysts was prepared by a step impregnation method with gradual increased Ce amount. Compared to the commercial V-W/Ti catalysts, the V-xCe/Ti catalysts exhibited considerably higher COx selectivity during the oxidation of naphthalene (Nap), and less intermediates or by-products were detected both in gas phase and on the surface of the catalysts. Through a series of characterizations, it was found that abundance of weak basic sites in the form of OH was introduced by Ce, as well as the oxygen vacancies caused by the redox cycle of V4++Ce4+↔V5++Ce3+. The weak basic sites introduced by Ce could greatly enhance the Nap adsorption, and the Nap adsorbed was quickly converted to naphthol on Ce-OH. Furthermore, V existed at a high valence with the interaction of V and Ce, and the oxygen vacancies also increased the Oads and OOH. It improved the redox ability and the regeneration of Ce-OH on V-xCe/Ti catalysts. The intermediates could be further oxidized, and the Ce-OH consumed in the reaction could recover quickly. Therefore, almost 100% Nap conversion and a high COx selectivity was observed in the V-xCe/Ti catalysts system.

Evidence of economic development revealed in centennial scale sedimentary records of organic pollutants in Huguangyan Marr Lake

Sedimentary records of polycyclic aromatic hydrocarbons (PAHs) and phthalates could reflect energy consumption and industrial production adjustment. However, there is limited knowledge about their effects on variations of PAH and phthalate compositions in the sediment core. The PAH and phthalate sedimentary records in Huguangyan Maar Lake in Guangdong, China were constructed, and random forest models were adopted to quantify the associated impact factors. Sums of sixteen PAH (∑16 PAH) and seven phthalate (∑7 PAE) concentrations in the sediment ranged from 28.8 to 1110 and 246-4290 μg/kg dry weight in 1900-2020. Proportions of 5-6 ring PAHs to the ∑16 PAHs increased from 32.0 %-40.7 % in 1900-2020 with increased coal and petroleum consumption, especially after 1980. However, those of 2-3 ring PAHs decreased from 30.7 % to 23.6 % due to the biomass substitution with natural gas. The proportions of bis (2-ethylhexyl) phthalate to the ∑7 PAEs decreased from 52.3 %-29.1 % in 1900-2020, while those of di-isobutyl phthalate increased (13.7 % to 42.3 %). The shift from traditional plasticizers to non-phthalates drove this transformation, though the primary plastic production is increasing. Our findings underscore the effectiveness of optimizing energy structures and updating chemical products in reducing organic pollution in aquatic environments.

The effect of bioturbation on the release behavior of polycyclic aromatic hydrocarbons from sediments: A sediment-seawater microcosm experiment combined with a fugacity model

The effects of two benthonic species, Perinereis aibuhitensis and Matuta planipes Fabricius, on the release of polycyclic aromatic hydrocarbons (PAHs) from sediments were investigated using a sediment-seawater microcosm. A Level IV fugacity model was used to simulate the behavior and fate of PAHs in the environment. This study revealed that both benthos significantly influenced the release of PAHs, and Matuta planipes Fabricius had a stronger disturbance effect than another. The final concentrations of Matuta planipes Fabricius group, Perinereis aibuhitensis group and the control group in the seawater phase reached 10.8, 9.94 and 7.90 μg/L, respectively. There were certain differences in the behaviour of the two benthonic species. Matuta planipes Fabricius caused more sediment resuspension, while Perinereis aibuhitensis increased the total organic carbon (TOC) content in the environment. The vertical concentration distribution of sediment indicated that vertical mixing was slightly stronger in the Matuta planipes Fabricius group than that in the Perinereis aibuhitensis group. The fugacity model effectively simulated the release behavior of PAHs, providing insight into PAH transport and distribution. The results demonstrated that bioturbation could promote the release of PAHs from seawater. The amount of PAHs released was significantly correlated with the biological habits of the benthos.

Rapid and Comprehensive Analysis of 41 Harmful Substances in Multi-Matrix Products by Gas Chromatography-Mass Spectrometry Using Matrix-Matching Calibration Strategy

Harmful substances in consumer goods pose serious hazards to human health and the environment. However, due to the vast variety of consumer goods and the complexity of their substrates, it is difficult to simultaneously detect multiple harmful substances in different materials. This paper presents a method for the simultaneous determination of 41 harmful substances comprising 17 phthalates (PAEs), 8 organophosphate flame retardants (OPFRs), and 16 polycyclic aromatic hydrocarbons (PAHs) in five types of products using the matrix-matching calibration strategy. The method employs an efficient ultrasonic extraction procedure using a mixture of dichloromethane and methylbenzene, followed by dissolution-precipitation and analysis through gas chromatography-mass spectrometry. Compared with previous experiments, we established a universal pretreatment method suitable for multi-matrix materials to simultaneously determine multiple harmful substances. To evaluate the effects of the matrix on the experimental results, we compared neat standard solutions and matrix-matching standard solutions. The results demonstrated that all compounds were successfully separated within 30 min with excellent separation efficiency. Additionally, the linear relationships of all analytes showed strong correlation coefficients (R2) of at least 0.995, ranging from 0.02 mg/L to 20 mg/L. The average recoveries of the target compounds (spiked at three concentration levels) were between 73.6 and 124.1%, with a relative standard deviation (n = 6) varying from 1.2% to 9.9%. Finally, we tested 40 different materials from consumer products and detected 16 harmful substances in 31 samples. Overall, this method is simple and accurate, and it can be used to simultaneously determine multiple types of hazardous substances in multi-matrix materials by minimizing matrix effects, making it an invaluable tool for ensuring product safety and protecting public health.

Atmospheric polycyclic aromatic hydrocarbons in India: geographical distribution, sources and associated health risk-a review

Atmospheric distribution of polycyclic aromatic hydrocarbons and associated human health risks have been studied in India. However, a comprehensive overview is not available in India, this review highlights the possible sources, and associated cancer risks in people living in different zones of India. Different databases were searched for the scientific literature on polycyclic aromatic hydrocarbons in ambient air in India. Database searches have revealed a total of 55 studies conducted at 139 locations in India in the last 14 years between 1996 and 2018. Based on varying climatic conditions in India, the available data was analysed and distributed with four zone including north, east, west/central and south zones. Comparatively higher concentrations were reported for locations in north zone, than east, west/central and south zones. The average concentrations of ∑PAHs is lower in east zone, and concentrations in north, west/central and south zones are higher by 1.67, 1.47, and 1.12 folds respectively than those in east zone. Certain molecular diagnostic ratios and correlation receptor models were used for identification of possible sources, which aided to the conclusion that both pyrogenic and petrogenic activities are the mixed sources of PAH emissions to the Indian environment. Benzo(a)pyrene toxicity equivalency for different zones is estimated and presented. Estimated Chronic daily intake (CDI) due to inhalation of PAHs and subsequently, cancer risk (CR) is found to be ranging from extremely low to low in various geographical zones of India.

Dust dynamics: distribution patterns of semi-volatile organic chemicals across particle sizes in varied indoor microenvironments

An extensive analysis of the distribution patterns of three distinct classes of semi-volatile organic chemicals (SVOCs)-phthalates (PAEs), organophosphate flame retardants (OPFRs), and polycyclic aromatic hydrocarbons (PAHs)-across four distinct size fractions of dust (25, 50, 100, and 200 μm) was conducted. The dust samples were sourced from AC filter, covered car parking lots, households, hotels, mosques, and car floors. To generate the four fractions, ten dust samples from each microenvironment were pooled and sieved utilizing sieving apparatus with the appropriate mesh size. Selected SVOCs were quantified utilizing gas chromatography-mass spectrometry in electron impact (EI) mode. Results unveiled diverse contamination levels among dust fractions, showcasing car parking lot dust with the lowest chemical contamination, while car floor dust displayed the highest levels of PAHs and OPFRs, peaking at 28.3 µg/g and 43.2 µg/g, respectively. In contrast, mosque and household floor dust exhibited the highest concentrations of phthalates, with values of 985 µg/g and 846 µg/g, respectively. Across the analyzed microenvironments, we observed a trend where concentrations of SVOCs tended to rise as dust particles decreased in size, forming a visually striking pattern. This phenomenon was particularly pronounced in dust samples collected from car floors and parking lots. Among SVOCs, PAEs emerged as the predominant contributors with > 90% followed by OPFRs and PAHs. The high levels of OPFRs in car floor dust align logically with the fact that numerous interior components of cars are treated with OPFRs, within a compact indoor microenvironment, to comply to fire safety regulations. Furthermore, petroleum products are a major source of PAHs in the environment and all the sampled cars in the study had combustion engines. Consequently, car dust is more likely to be polluted with PAHs stemming from petroleum combustion. Although previous investigations have noted an increase in heavy metals and brominated flame retardants with decreasing dust particles, this is the first study analyzing these SVOCs in different fractions of dust from various microenvironments. However, aside from two specific microenvironments, the observed pattern of escalating SVOC concentrations with smaller dust particle sizes was not corroborated among the examined microenvironments. This divergence in concentration trends suggests the potential involvement of supplementary variables in influencing SVOC distributions within dust particles.

Biochars assisted phytoremediation of polycyclic aromatic hydrocarbons contaminated agricultural soil: Dynamic responses of functional genes and microbial community

A biochar-intensified phytoremediation experiment was designed to investigate the dynamic effects of different biochars on polycyclic aromatic hydrocarbon (PAH) removal in ryegrass rhizosphere contaminated soil. Maize and wheat straw biochar pyrolyzed at 300 °C and 500 °C were amended into PAH-contaminated soil, and then ryegrass (Lolium multiflorum L.) was planted for 90 days. Spearman's correlations among PAH removal, enzyme activity, abundance of PAH-ring hydroxylating dioxygenase (PAH-RHDα), and fungal and bacterial community structure were analyzed to elucidate the microbial degradation mechanisms during the combined remediation process. The results showed that 500 °C wheat straw biochar had higher surface area and more nutrients, and significantly accelerated the phytoremediation of PAHs (62.5 %), especially for high molecular weight PAH in contaminated soil. The activities of urease and dehydrogenase and the abundance of total and PAH-degrading bacteria, which improved with time by biochar and ryegrass, had a positive correlation with the removal rate of PAHs. Biochar enhanced the abundance of gram-negative (GN) PAH-RHDα genes. The GN PAH-degraders, Sphingomonas, bacteriap25, Haliangium, and Dongia may play vital roles in PAH degradation in biochar-amended rhizosphere soils. Principal coordinate analysis indicated that biochar led to significant differences in fungal community structures before 30 days, while the diversity of the bacterial community composition depended on planting ryegrass after 60 days. These findings imply that the structural reshaping of microbial communities results from incubation time and the selection of biochar and ryegrass in PAH-contaminated soils. Applying 500 °C wheat straw biochar could enhance the rhizoremediation of PAH-contaminated soil and benefit the soil microbial ecology.

Photodegradation of polycyclic aromatic hydrocarbons on soil surface: Kinetics and quantitative structure-activity relationship (QSAR) model development

Polycyclic aromatic hydrocarbons (PAHs) have attracted much attention because of their widespread existence and toxicity. Photodegradation is the main natural decay process of PAHs in soil. The photodegradation kinetics of benzopyrene (BaP) on 16 kinds of soils and 10 kinds of PAHs on Hebei (HE) soil were studied. The results showed that BaP had the highest degradation rate in Shaanxi (SN) soil (kobs = 0.11 min-1), and anthracene (Ant) was almost completely degraded after 16 h of irradiation in HE soil. Two quantitative structure-activity relationship (QSAR) models were established by the multiple linear regression (MLR) method. The developed QSAR models have good stability, robustness and predictability. The model revealed that the main factors affecting the photodegradation of PAHs are soil organic matter (SOM) and the energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital (Egap). SOM can function as a photosensitizer to induce the production of active species for photodegradation, thus favoring the photodegradation of PAHs. In addition, compounds with lower Egap are less stable and more reactive, and thus are more prone to photodegradation. Finally, the QSAR model was optimized using machine learning approach. The results of this study provide basic information on the photodegradation of PAHs and have important significance for predicting the environmental behavior of PAHs in soil.

Characteristics of polycyclic aromatic hydrocarbons (PAHs) removal by nanofiltration with and without coexisting organics

Polycyclic aromatic hydrocarbons (PAHs) are contaminants of great concern owing to their persistence, toxicity, and bioaccumulation in aquatic environments. In this study, nanofiltration (NF) was used to investigate the removal of naphthalene (NAP) and phenanthrene (PHE) using three membranes of NF270, NF90, and DK. Subsequently, we examined the effects of coexisting organics on PAHs removal. Based on the results, DK was determined to be the optimal membrane for removing PAHs by comparing the membrane flux and pollutant rejection. The membrane flux reached 34.32 L/m2·h, and the NAP and PHE rejections were 92.21% and 97.85%, respectively, at transmembrane pressure (TMP) of 5 bar using DK. Coexisting organics decreased the membrane fluxes of NF270 and DK in the following order: protein > glucose > humic acid. The NAP and PHE rejections were obviously improved using NF270 in the following order: humic acid > protein > glucose. The PHE rejection was slightly improved using DK. A low concentration of organics could reduce the NAP rejection using DK; however, the NAP rejection could be restored at high concentrations of organics, except for humic acid. Coexisting organics could cause severe membrane fouling. The order of the effect of different coexisting organics on membrane fouling was protein > humic acid > glucose. The total investment and operating costs were about 1.47 and 0.187 million dollars, respectively, for treating PAHs solution using DK when the feed flow was 300 m3/d.

Global trade-driven transfer of atmospheric polycyclic aromatic hydrocarbon emissions and associated human inhalation exposure risk

Polycyclic aromatic hydrocarbons (PAHs) are of significant public concern because of their toxicity and long-range transport potential. Extensive studies have been conducted to explore the source-receptor relationships of PAHs via atmospheric transport. However, the transfer of trade-driven regional and global PAHs is poorly understood. This study estimated the virtual PAHs emission transfer embodied in global trade from 2004 to 2014 and simulated the impact of international trade on global contamination and associated human inhalation exposure risk of PAHs. Results show that trade-driven PAHs flowed primarily from developed to less-developed regions, particularly in those regions with intensive heavy industries and transportation. As the result, international trade resulted in an increasing risk of lung cancer induced by exposure to PAHs (27.8% in China, 14.7% in India, and 11.3% in Southeast Asia). In contrast, we found decreasing risks of PAHs-induced lung cancer in Western Europe (63.2%) and the United States (45.9%) in 2004. Our findings indicate that final demand and emission intensity are the key driving factors contributing to rising and falling consumption-based PAHs emissions and related health risk respectively. The results could provide a useful reference for global collaboration in the reduction of PAHs pollution and related health risks.

Sources and influences of atmospheric nonpolar organic compounds in Nanchang, central China: Full-year monitoring with a focus on winter pollution episodes

Nonpolar organic compounds (NPOCs) are found in atmospheric aerosols and have significant implications for environmental and human health. Although many studies have quantitatively estimated the sources of NPOCs in different cities, few have evaluated their main influencing factors (e.g., emissions and meteorological conditions) at relatively long (e.g., different seasons) and short timescales (e.g., several days during pollution episodes). A better understanding of this issue could optimise strategies for dealing with organic contamination in atmospheric particulate matter. NPOCs (including n-alkanes, PAHs and hopanes) in fine particulate matter (PM2.5) were sampled daily at Nanchang, China, from 1 November 2020 to 31 October 2021. Analyses of specific biomarkers and diagnostic ratios indicate that the NPOCs mainly had anthropogenic sources. The quantitative estimates of a positive matrix factorization model show that fossil fuel and biomass combustion were the main sources of n-alkanes (contributing 64.8 %), while vehicle exhaust was the main source of PAHs (47.0 %) and hopanes (52.3 %). Seasonally, the contributions from coal and/or biomass combustion were higher in autumn and winter (40.2-56.3 %) than in spring and summer (25.7-44.3 %), while contributions from natural plants, petroleum volatilization and vehicle exhaust were higher in spring and summer (14.7-63.5 %) than in autumn and winter (8.1-48.9 %). Redundancy analysis shows that increased emissions, especially from coal and/or biomass combustion, are the main cause of increases in NPOCs, during both annual sampling periods and winter pollution episodes. Over the year, higher temperature and longer sunshine hours correspond to lower NPOC concentrations. In winter pollution episodes, increases in temperature and relative humidity correspond to increases in NPOC concentrations. Our results suggest that controlling primary emissions, especially from coal and biomass combustion, may be an effective way to prevent increases in NPOC concentrations.

Characterisation of polycyclic aromatic hydrocarbons associated with indoor PM0.1 and PM2.5 in Hanoi and implications for health risks

Polycyclic aromatic hydrocarbons (PAHs) associated with indoor PM pose a high risk to human health because of their toxicity. A total of 160 daily samples of indoor PM2.5 and PM0.1 were collected in Hanoi and analysed for 15 PAHs. In general, the concentrations of carcinogenic PAHs (car-PAHs) accounted for 21% ± 2%, 19.1% ± 2%, and 26% ± 3% of the concentrations of 15 PAHs in PM2.5, PM0.1-2.5, and PM0.1, respectively. Higher percentages of car-PAHs were found in smaller fractions (PM0.1), which can be easily deposited deep in the pulmonary regions of the human respiratory tract. The concentrations of 15 PAHs were higher in winter than in summer. The most abundant PAH species were naphthalene and phenanthrene, accounting for 11%-21% and 19%-23%, respectively. The PAH content in PM0.1 was almost twice as high as those in PM2.5 and PM0.1-2.5. Principal component analysis found that vehicle emissions and the combustion of biomass and coal were the main outdoor sources of PAHs, whereas indoor sources included cooking activities, the combustion of incense, scented candles, and domestic uses in houses. According to the results, 60%-90% of the PM0.1-bound BaP(eq) was deposited in the alveoli region, whereas 63%-75% of the PM2.5-bound BaP(eq) was deposited in head airways (HA), implying that most of the particles deposited in the HA region were PM0.1-2.5. The contributions of dibenz[a,h]anthracene and benzo[a]pyrene were dominant and contributed from 36% to 51% and 31%-50%, respectively, to the carcinogenic potential, whereas benzo[a]pyrene contributed from 30% to 49% to the mutagenic potential for both size fractions. The incremental lifetime cancer risk, simulated by Monte Carlo simulation, was within the limits set by the US EPA, indicating an acceptable risk for the occupants. These results provide an additional scientific basis for protecting human health from exposure to indoor PAHs.

Critical review on the formations and exposure of polycyclic aromatic hydrocarbons (PAHs) in the conventional hydrocarbon-based fuels: Prevention and control strategies

Polycyclic aromatic hydrocarbons (PAHs) are widely present in the atmosphere and primarily originate from the incomplete burning of fossil fuels and biofuels. Exposure to PAHs leads to harmful effects on human health and the environment. Diesel engines are a major source of PAH production in the transportation sector. Various approaches have been employed to reduce PAH emissions from diesel engines, including the use of biodiesel, green gaseous fuels, exhaust gas recirculation, exhaust after-treatment, and genetically modifying biodiesel with nanoparticles. This review focuses on PAH emissions from different generations of fuels and examines the remedial control actions taken to mitigate PAH formation. The study underscores the necessity for effective regulation of emissions from diesel engines, especially in developing countries where the reliance on fossil fuels is significant. Biodiesel has shown promise in reducing PAHs and carcinogenic pollutants, with higher biodiesel concentrations resulting in lower PAH formation. Replacing diesel with biodiesel and optimizing engine operating conditions are feasible methods to reduce PAH levels in the atmosphere. The use of nanoparticles in fuel blends and higher oxygen content in combustion chambers are also considered potential strategies for pollutant reduction. Additionally, the utilization of hydrogen and ammonia as secondary fuels has been explored as promising alternatives to fossil fuels. The study highlights the importance of further research on the presence of residual PAHs in the atmosphere and the implementation of strategies to curtail vehicular emissions.

Raman spectroscopy combined with partial least squares (PLS) based on hybrid spectral preprocessing and backward interval PLS (biPLS) for quantitative analysis of four PAHs in oil sludge

Polycyclic aromatic hydrocarbons (PAHs) contained in a large amount of oily sludge produced in petroleum and petrochemical production has become one of the main environmental protection concerns in the industry. The accurate determination of PAHs is of great significance in the field of petroleum geochemistry and environmental protection. In this study, Raman spectroscopy combined with partial least squares (PLS) based on different hybrid spectral preprocessing methods and variable selection strategies was proposed for quantitative analysis of phenanthrene, fluoranthrene, fluorene and naphthalene (Phe, Flt, Flu and Nap) in oil sludge. At first, PAHs in oily sludge was extracted by solid-liquid extraction with methanol as extractant, and Raman spectra of 21 oily sludge samples were collected by portable Raman spectrometer. And then, the influence of first derivative (D1st), wavelet transform (WT) and their hybrid spectral preprocessing on the predictive performance of the PLS calibration model was discussed. Thirdly, biPLS (backward interval partial least squares) was used to optimize the input variables before and after the hybrid spectral preprocessing methods, and the influence of biPLS and the hybrid spectral preprocessing sequence on the predictive performance of the PLS calibration model was discussed. Finally, the predictive performance of the PLS calibration model was optimized according to the results of leave-one-out cross-validation (LOOCV) method. The results show that the biPLS-D1st-WT-PLS calibration model established by using biPLS first to select the characteristic variables, followed by hybrid spectral preprocessing of the characteristic variables, has better prediction performance for Flt (determination coefficient of prediction (R2P) = 0.9987, and the mean relative error of prediction (MREP) = 0.0606). For Phe, Flu and Nap, the WT-biPLS-PLS calibration model has a better predictive effect (R2P are 0.9995, 0.9996 and 0.9983, and MREP are 0.0426, 0.0719 and 0.0497, respectively). In general, portable Raman spectroscopy combined with PLS calibration model based on different hybrid spectral preprocessing and variable selection strategies has achieved good prediction results for quantitative analysis of four PAHs in oily sludge. It is a new strategy to firstly select the characteristic variables of the original spectra, and secondly to preprocess the characteristic variables by the hybrid spectral preprocessing, which will provide a new idea for the establishment of quantitative analysis methods for PAHs in oily sludge.

Levels and sources of polycyclic aromatic hydrocarbons (PAHs) near hospitals and schools using leaves and barks of Sambucus nigra and Acacia melanoxylon

Polycyclic aromatic hydrocarbons (PAHs) are among the most studied organic compounds in urban environments, due to their known threat to human health. This study extends the current knowledge regarding the ability of different vegetative parts of different tree species to accumulate PAHs. Moreover, exposure intensity to PAHs in areas frequented by population susceptible to adverse health effects of air pollution is evaluated. For this, leaves and barks of Sambucus nigra (S. nigra) and Acacia melanoxylon (A. melanoxylon) were collected at urban areas in the Andean city of Quito, at seven points near hospitals and schools. A methodology, previously developed, for the extraction, purification, and quantification of PAHs associated with the leaves and bark of S. nigra was employed and also validated for leaves and bark of A. melanoxylon. The total PAH level varied from 119.65 ng g-1 DW (dry weight) to 1969.98 ng g-1 DW (dry weight) with naphthalene (Naph), fluoranthene (Flt), pyrene (Pyr), chrysene (Chry), and benzo[a]pyrene (BaP) predominating in all samples. The results indicate that the leaves and bark of tree species studied have certain abilities to bio-accumulate PAH according to their molecular weight. The leaves of S. nigra and bark of A. melanoxylon showed the highest ability to accumulate PAHs, mainly those with high and medium molecular weight, respectively. The highest incidence of light molecular weight PAHs was found in the leaves of A. melanoxylon. Furthermore, coal combustion, biomass burning, and vehicle emissions were identified as the main PAHs sources. Concentrations of PAHs associated with tree species suggest an affectation in areas frequented by populations susceptible to air pollution. This fact shows the importance of regulatory scheme to significantly improve the air quality in the city integrating a knowledge-based decision-making.

When aerobic granular sludge faces emerging contaminants: A review

The evolution of emerging contaminants (ECs) has caused greater requirements and challenges to the current biological wastewater treatment technology. As one of the most promising biological treatment technologies, the aerobic granular sludge (AGS) process also faces the challenge of ECs. This study summarizes the recent progress and characteristics of several representative ECs (persistent organic pollutants, endocrine disrupting chemicals, antibiotics, and microplastics) in AGS systems that have garnered widespread attention. Additionally, the biodegradation and adsorption mechanisms of ECs were discussed, and the interactions between various ECs and AGS was elucidated. The importance of extracellular polymeric substances for the stabilization of AGS and the removal of ECs is also discussed. Knowledge gaps and future research directions that may enable the practical application of AGS are highlighted. Overall, AGS processes show great application potential and this review provides guidance for the future implementation of AGS technology as well as elucidating the mechanism of its interaction with ECs.

Degradation of polycyclic aromatic hydrocarbons in aquatic environments by a symbiotic system consisting of algae and bacteria: green and sustainable technology

Polycyclic aromatic hydrocarbons (PAHs) are genotoxic, carcinogenic, and persistent in the environment and are therefore of great concern in the environmental protection field. Due to the inherent recalcitrance, persistence and nonreactivity of PAHs, they are difficult to remediate via traditional water treatment methods. In recent years, microbial remediation has been widely used as an economical and environmentally friendly degradation technology for the treatment of PAH-contaminated water. Various bacterial and microalgal strains are capable of potentially degrading or transforming PAHs through intrinsic metabolic pathways. However, their biodegradation potential is limited by the cytotoxic effects of petroleum hydrocarbons, unfavourable environmental conditions, and biometabolic limitations. To address this limitation, microbial communities, biochemical pathways, enzyme systems, gene organization, and genetic regulation related to PAH degradation have been intensively investigated. The advantages of algal-bacterial cocultivation have been explored, and the limitations of PAHs degradation by monocultures of algae or bacteria have been overcome by algal-bacterial interactions. Therefore, a new model consisting of a "microalgal-bacterial consortium" is becoming a new management strategy for the effective degradation and removal of PAHs. This review first describes PAH pollution control technologies (physical remediation, chemical remediation, bioremediation, etc.) and proposes an algal-bacterial symbiotic system for the degradation of PAHs by analysing the advantages, disadvantages, and PAH degradation performance in this system to fill existing research gaps. Additionally, an algal-bacterial system is systematically developed, and the effects of environmental conditions are explored to optimize the degradation process and improve its technical feasibility. The aim of this paper is to provide readers with an effective green and sustainable remediation technology for removing PAHs from aquatic environments.

Emission factors of oxygenated polycyclic aromatic hydrocarbons from ships in China

The rapid growth of maritime traffic, transportation, and fishery activities has increased shipping emissions and degraded the air quality in coastal areas. As a result, controlling ocean-based pollution sources have become increasingly important. This study investigated the real-world emission characteristics of oxygenated polycyclic aromatic hydrocarbons (OPAHs, a group of highly toxic semi-volatile organic compounds) from five types of offshore ships using diesel oil: small and medium fishing ships, tug boats, ferry, and engineering ships, under various driving mode. Both gaseous and particle emission factors (EF) of four specific OPAHs were determined in our study. Among the OPAHs species emitted from ships, 9-fluorenone (9FO; 72%) and anthrathrace-9,10-quinone (ATQ; 25%) were the most abundant. The arithmetic mean of the sum of gaseous OPAHs EFs for all ships in this study was 2.5 ± 4.4 mg/kg fuel burned, and the mean particulate OPAHs EF was 4.7 ± 7.9 mg/kg. Small fishing ships had the highest total OPAHs EFs (31.0 ± 17.0 mg/kg). Apart from small fishing ships, there was no significant difference in the total EF of OPAHs for the other four types of ships. The emissions of the four OPAHs are predominantly in the particulate phase. There were no significant differences in the emissions of the four OPAHs under different driving mode. According to estimates, the annual OPAH emissions from the four types of ships in Hainan in 2017 were approximately 4.2 (range: 2.7-7.0) tons, dwarfing the OPAH emissions from diesel-powered on-road vehicles in China (23.5 kg).

Molecular distribution, sources and potential health risks of fine particulate-bound polycyclic aromatic hydrocarbons during high pollution episodes in a subtropical urban city

Abundance of fine particulate-bound 16 priority polycyclic aromatic hydrocarbons (PAHs) was investigated to ascertain its sources and potential carcinogenic health risks in Varanasi, India. The city represents a typical urban settlement of South Asia having particulate exposure manyfold higher than standard with reports of pollution induced mortalities and morbidities. Fine particulates (PM2.5) were monitored from October 2019 to May 2020, with 32% of monitoring days accounting ≥100 μgm-3 of PM2.5 concentration, frequently from November to January (99% of monitoring days). The concentration of 16 priority PAHs varied from 24.1 to 44.6 ngm-3 (mean: 33.1 ± 3.2 ngm-3) without much seasonal deviations. Both low (LMW, 56%) and high molecular weight (HMW, 44%) PAHs were abundant, with Fluoranthene (3.9 ± 0.4ngm-3) and Fluorene (3.5 ± 0.3ngm-3) emerged as most dominating PAHs. Concentration of Benzo(a)pyrene (B(a)P, 0.5 ± 0.1ngm-3) was lower than the national standard as it contributed 13% of total PAHs mass. Diagnostic ratios of PAH isomers indicate predominance of pyrogenic sources including emissions from biomass burning, and both from diesel and petrol-driven vehicles. Source apportionment using receptor model revealed similar observation of major PAHs contribution from biomass burning and fuel combustion (54% of source contribution) followed by coal combustion for residential heating and cooking purposes (44%). Potential toxicity of B[a]P equivalence ranged from 0.003 to 1.365 with cumulative toxicity of 2.13ngm-3. Among the PAH species, dibenzo[h]anthracene contributed maximum toxicity followed by B[a]P, together accounting 86% of PAH induced carcinogenicity. Incremental risk of developing cancer through lifetime exposure (ILCR) of PAHs was higher in children (3.3 × 10-4) with 56% contribution from LMW PAHs, primarily through ingestion and dermal contact. Adults in contrast, were more exposed to inhale airborne PAHs with cumulative ILCR of 2.2 × 10-4. However, ILCR to PM2.5 exposure is probably underestimated considering unaccounted metal abundance thus, require source-specific control measures.

Analysis of PAHs content, source and risk assessment in surface sediments from Laizhou Bay and Bohai Bay

To understand the levels of PAHs and ecological risks to the marine environment in Laizhou Bay and Bohai Bay, 33 sediment samples were collected in the region for analysis. PAH concentrations ranged from 98.22 ng·g-1 (dw) to 239.01 ng·g-1 (dw). PAHs in the region are at low to medium pollution levels compared to studies worldwide. Diagnostic ratios and PCA indicate that PAHs are primarily sourced from fuel combustion. PAHs carried into the Bohai Sea by means of river water and sediment are more likely to settle to the seafloor as opposed to diffuse. This results in a slightly higher proportion of low-ring PAHs than high-ring PAHs. Low-ring PAHs accounted for 56 % of the total. Low-ring PAHs are key contributors to ecosystem risk. The SQGs and RQ∑PAHs show that PAHs do not pose a considerable ecological danger within the region.

Air pollution prevention in central China: Effects on particulate-bound PAHs from 2010 to 2018

Long-term trends in particulate-bound polycyclic aromatic hydrocarbon (PAH) concentrations in air in Zhengzhou (a severely polluted city in central China) between 2010 and 2018 were studied to assess the effectiveness of an air pollution prevention and control action plan (APPCAP) implemented in 2013. The PM2.5, sum of 16 PAHs (Σ16 PAHs), benzo[a]pyrene (BaP), and BaP toxic equivalent concentrations were high before 2013 but 41%, 77%, 77%, and 78% lower, respectively, after the APPCAP. The maximum daily Σ16 PAHs concentration between 2014 and 2018 was 338 ng/m3, 65% lower than the maximum of 961 ng/m3 between 2010 and 2013. The ratio between the Σ16 PAHs concentrations in winter and summer decreased over time and was 8.0 in 2011 and 1.5 in 2017. The most abundant PAH was benzo[b]fluoranthene, for which the 9-year mean concentration was 14 ± 21 ng/m3 (15% of the Σ16 PAHs concentration). The mean benzo[b]fluoranthene concentration decreased from 28 ± 27 ng/m3 before to 5 ± 4 ng/m3 after the APPCAP (an 83% decrease). The mean daily BaP concentrations were 0.1-62.8 ng/m3, and >56% exceeded the daily standard limit of 2.5 ng/m3 for air. The BaP concentration decreased from 10 ± 8 ng/m3 before to 2 ± 2 ng/m3 after the APPCAP (a 77% decrease). Diagnostic ratios and positive matrix factorization model results indicated that coal combustion and vehicle exhausts were important sources of PAHs throughout the study period, contributing >70% of the Σ16 PAHs concentrations. The APPCAP increased the relative contribution of vehicle exhausts from 29% to 35% but decreased the Σ16 PAHs concentration attributed to vehicle exhausts from 48 to 12 ng/m3. The PAH concentration attributed to vehicle exhausts decreased by 79% even though vehicle numbers strongly increased, indicating that pollution caused by vehicles was controlled well. The relative contribution of coal combustion remained stable but the PAH concentration attributed to coal combustion decreased from 68 ng/m3 before to 13 ng/m3 after the APPCAP. Vehicles made dominant contributions to the incremental lifetime cancer risk (ILCRs) before and after the APPCAP even though the APPCAP decreased the ILCRs by 78%. Coal combustion was the dominant source of PAHs but contributed only 12-15% of the ILCRs. The APPCAP decreased PAH emissions and changed the contributions of different sources of PAHs, and thus strongly affected the overall toxicity of PAHs to humans.

Upwelling impact and lateral transport of dissolved PAHs in the Taiwan Strait and adjacent South China Sea

The spatial distribution and depth profile of dissolved polycyclic aromatic hydrocarbons (PAHs) were investigated in the western Taiwan Strait (TWS) and northeastern South China Sea (SCS) during the southwest monsoon for a comprehensive study of spatial distribution, potential sources, upwelling, and lateral PAHs transport flux to assess the impacts of oceanic processes. The concentrations of ∑14PAHs were 33 ± 14 ng L-1 and 23 ± 11 ng L-1 in western TWS and northeastern SCS, respectively. A minor difference in potential sources in different areas was shown in principle component analysis results, which illustrated mixed sources (petrogenic and pyrogenic) in western TWS and petrogenic sources in northeastern SCS. An "enrichment in surface or deep but depletion in medium water" distribution pattern of PAHs depth profile during summertime was observed in Taiwan Bank, which was potentially influenced by the upwelling. The greatest lateral ∑14PAHs transport flux was found along the Taiwan Strait Current area (43.51 g s-1), followed by those along South China Sea Warm Current and Guangdong Coastal Current areas. Though the oceanic response to PAHs varied relatively slowly, the ocean current was a less-dominant pathway for PAHs exchange between the SCS and the East China Sea (ECS).

Burkholderia cepacia immobilized onto rGO as a biomaterial for the removal of naphthalene from wastewater

As one of the polycyclic aromatic hydrocarbons (PAHs), naphthalene is of serious environmental concern due to its carcinogenicity, persistence and refractory degradation. In this study, a new functional biomaterial based on Burkholderia cepacia (BK) immobilized on reduced graphene oxide (rGO) was prepared, resulting in the removal of 99.0% naphthalene within 48 h. This was better than the 67.3% for free BK and 55.6% for rGO alone. Various characterizations indicated that reduced graphene oxide-Burkholderia cepacia (rGO-BK) was successfully synthesized and secreted non-toxic and degradable surfactants which participated in the degradation of naphthalene. The adsorption kinetics and degradation kinetics conformed best to non-linear pseudo-second-order and pseudo-first-order kinetic models, respectively. Demonstrated in this work is that removing naphthalene by rGO-BK involved both chemically dominated adsorption and biodegradation. As well, GC-MS analysis revealed two things: firstly, that the degraded products of naphthalene were dibutyl phthalate, diethyl phthalate, phthalic acid, and benzoic acid; and secondly, two potentially viable biodegradation pathways of naphthalene by rGO-BK could be proposed. Finally, for practical application experiment, the rGO-BK was exposed to river water samples and generated 99% removal efficiency of naphthalene, so this study offers new insights into biomaterials that can remove naphthalene.

In vitro toxicity and lung cancer risk: Atmospheric particulate matter from a city in southeastern Brazil impacted by biomass burning

The effects of PM10 on human health were investigated using samples collected in São Carlos city (São Paulo state), by the determination of the concentrations of PAHs and derivatives, together with evaluations of cytotoxicity and the formation of ROS in in vitro tests. In 2016, the mean concentrations of PM10, ΣPAHs, Σoxy-PAHs, Σnitro-PAHs, Σsaccharides, and Σions were 21.12 ± 9.90 μg m-3, 1.47 ± 1.70 ng m-3, 0.37 ± 0.31 ng m-3, 0.84 ng m-3, 119.91 ± 62.14 ng m-3, and 5.66 ± 4.52 μg m-3, respectively. The PM10 concentrations did not exceed the limit thresholds set by national legislation, however, the annual lung cancer risk calculated was 2.59 ± 1.22 cases per 100,000 people, in the dry season, which accounts for the annual risk (April to September). Moreover, the carcinogenic activities of the PAHs mixture were more than 1000-fold higher in the dry season (dry season: BaPeq = 0.30 ng m-3; wet season BaPeq = 0.02 ng m-3). The concentrations of most analytes were also higher during the dry season, as had already been demonstrated in the same city. This was due to reductions in precipitation, relative humidity and air temperature, and increased biomass burning, which was the main source of PM10 in the city in 2016 (contribution rate of more than 50%). Toxicological results also showed the negative impacts of PM10, exposure to PM10 extracts for 72 h reduced the viability of A549 and MRC5 cells, and the formation of ROS was observed. The cellular responses obtained using combined and individual extracts of PM10 differed and were sometimes associated with specific compounds. These demonstrate the importance of monitoring PM toxicity using different approaches and the main anthropogenic sources' contribution. Therefore, to improve air quality and human health, existing legislation needs to be modified to incorporate these tests.

CeO2-Based Porous Carbonaceous Frameworks as Antioxidant Nanozymes for Scavenging Reactive Oxygen Species and Adsorbing Benzo[a]pyrene

Barbecue smoke, car exhaust, cigarette smoke, and other waste gases contain toxic reactive oxygen species (ROS) and polycyclic aromatic hydrocarbons (PAHs). Herein, CeO2-based porous carbonaceous frameworks (CeO2 PCFs) were explored as antioxidant nanozymes to scavenge ROS and absorb benzo[a]pyrene (B[a]P). Using cerium-based frameworks as the precursors, CeO2 PCFs were constructed by high-temperature calcination. Due to excellent superoxide dismutase-like and catalase-like activity, CeO2 PCFs could effectively eliminate superoxide radical, hydroxyl radical, and hydrogen peroxide. The 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) free radical scavenging assay had substantiated free radical scavenging ability of CeO2 PCFs. In addition, with a large surface area and porous structure, CeO2 PCFs could adsorb B[a]P efficiently. The designed CeO2 PCFs may provide a new opportunity as scavengers of ROS and absorbents of PAHs in some harmful gases.

Emission profiles, source identifications, and health risk of polycyclic aromatic hydrocarbons (PAHs) in a road tunnel located in Xi'an, China

Understanding the sources and characteristics of PM2.5-bound PAHs from traffic-related pollution can provide valuable data for mitigating air contamination from traffic in local urban regions. However, little information on PAHs is available regarding the typical arterial highway-Qinling Mountains No.1 tunnel in Xi'an. We estimated the profiles, sources, and emission factors of PM2.5-bound PAHs in this tunnel. The total PAH concentrations were 22.78 ng·m-3 and 52.80 ng·m-3 at the tunnel middle and exit, which were 1.09 and 3.84 times higher than that at the tunnel entrance. Pyr, Flt, Phe, Chr, BaP, and BbF were the dominant PAH species (representing approximately 78.01% of total PAHs). The four rings PAHs were dominant (58%) among the total PAH concentrations in PM2.5. The results demonstrated that diesel and gasoline vehicles exhaust emissions contributed 56.81% and 22.60% to the PAHs, respectively, while the corresponding value for together brakes, tyre wear, and road dust was 20.59%. The emission factors of total PAHs were 29.35 μg·veh-1·km-1, and emission factors of 4 rings PAHs were significantly higher than those of the other PAHs. The sum of ILCR was estimated to be 1.41×10-4, which accorded with acceptable level of cancer risk (10-6-10-4), PAHs should not ignored as they still affect the public health of inhabitants. This study shed light on PAH profiles and traffic-related sources in the tunnel, thereby facilitating the assessment of control measures targeting PAHs in local areas.

Polycyclic Aromatic Hydrocarbons in Topsoils Along the Taipu River Banks in the Yangtze River Delta, China: Occurrence, Source and Risk Assessment

Taipu River is an important transboundary river and drinking water source in the Yangtze River Delta, China. This study collected 15 topsoil samples along the Taipu River banks and subsequently determined the polycyclic aromatic hydrocarbons (PAHs) concentrations, sources, and ecological and health risks. The sum of toxic 15 PAHs concentrations ranged from 83.13 to 28342.53 ng/g, with a mean of 2828.69 ng/g. High molecular weight (HMW) PAHs were the dominant components and Indene (1,2,3, -cd) benzopyrene (InP) accounted for the highest proportion in individuals. The average PAH concentration in residential land was the highest, followed by those in industrial and agricultural land. The PAH concentration was positively related to contents of total carbon, total nitrogen, ammonium nitrogen, and aminopeptidase activity in soils. The mixed combustion of biomass, coal, and petroleum and traffic emissions could be the primary PAH contributors. The total PAHs at over half of sampling points had relatively high risk quotients and incremental lifetime cancer risk (ILCR) values, posing potential or great ecological threats and health risks.

Ecological pollution and health risk monitoring assessment of polycyclic aromatic hydrocarbons and heavy metals in surface water, southeastern Nigeria

Polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) are predominant pollutants linked with anthropogenic activities across a host of environmental mediums. The level of pollution, ecological and health risk were assessed in surface water from Ekulu in Enugu metropolis, Nigeria for 17 PAHs and selected HMs (As, Cd, Cr, Cu, Pb, Ni, Zn) components. PAHs and HMs were determined using a gas chromatography-flame ionization detector (GC-FID) and atomic adsorption spectrophotometer (AAS). The total PAHs in station A (3.17mg/l), B (1.51mg/l), and C (1.83mg/l) were due to high molecular weight (HMW) PAHs than low molecular weight (HMW) PAHs. HMs contents were within USEPA and WHO minimum contamination levels (MCL) except Cr and Pb. The molecular diagnostics of PAHs showed that incomplete combustion of carbonaceous compounds was dominant, while petrogenic was insignificant across all samples. The ecological indices of PAHs and HMs varied from medium to high pollution due to anthropogenic activities that pose a threat to the ecosystem. The non-carcinogenic models showed that hazard index (HI) ranged from PAHs (0.027 - 0.083) and HMs (0.0067 - 0.087) which is less than unity implying no adverse health issues. The lifetime cancer risk (LCR) for PAHs (4.21×10-4 - 9.61×10-4) and HMs (1.72×10-5 - 3.98×10-5) suggested significant cancer risk is possible over some time for a population of 1 in 10,000 and 100,000 for both PAHs and HMs exposure for 70 years. Therefore, there is an urgent need for proper pollution control and mitigation plan to preserve both age groups from being continuously exposed to anthropogenic activities in the Ekulu River and further study should be carried out to monitor the available toxicants.

Source apportionment and health impact assessment of atmospheric particulate matter in the city of São Carlos, Brazil

In this study, positive matrix factorization method was used for source apportionment of PM₁₀ in the city of São Carlos from 2015 to 2018. The annual mean concentrations of PM₁₀, 15 PAHs, 4 oxy-PAHs, 6 nitro-PAHs, 21 saccharides, and 17 ions in these samples were in the ranges 18.1 ± 6.99 to 25.0 ± 11.3 μg m^-3 for PM₁₀, 9.80 × 10^-1 ± 2.06 to 2.03 ± 8.54 × 10^-1 ng m^-3 for ΣPAHs, 83.9 ± 35.7 to 683 ± 521 pg m^-3 for Σoxy-PAHs, 1.79 × 10^-2 ± 1.23 × 10^-1 to 7.12 ± 4.90 ng m^-3 for Σnitro-PAHs, 83.3 ± 44.7 to 142 ± 85.9 ng m^-3 for Σsaccharides, and 3.80 ± 1.54 to 5.66 ± 4.52 μg m^-3 for Σions. For most species, the concentrations were higher in the dry season than in the rainy. This was related not only to the low rainfall and relative humidity characteristic of the dry season but also to an increase in fire spots recorded in the region between April and September every year from 2015 to 2018. A 4-factor solution provided the best description of the dataset, with the four identified sources of PM₁₀ being soil resuspension (28%), biogenic emissions (27%), biomass burning (27%), and vehicle exhaust together with secondary PM (18%). Although the PM₁₀ concentrations were not above the limit established by local legislation, the epidemiological study showed that by reducing PM_2.5 concentrations to the level recommended by the WHO, approximately 35 premature deaths per 100,000 population could be avoided annually. The results revealed that biomass burning continues to be one of the main anthropic sources of emissions to the atmosphere in the region, so it needs to be incorporated into the existing guidelines and policies to reduce the concentration of particulate matter to within the limits recommended by the WHO, in order to avoid premature deaths.

Seasonal variation, spatial distribution, and sources of PAHs in surface seawater from Zhanjiang bay influenced by land-based inputs

This study was carried out for a comprehensive understanding of the concentrations, seasonal variation, spatial distribution, sources, and land-based inputs of polycyclic aromatic hydrocarbons (PAHs) in surface seawater from Zhanjiang Bay (ZJB). Although the PAHs were ubiquitous, their concentrations were relatively low, and significant seasonal trends and spatial distributions were observed. Based on the diagnostic ratios and composition profiles, the PAHs found in this study mainly originated from coal/biomass burning, and petroleum and its combustion played an important role in the wet seasons. Furthermore, the PAHs from land-based inputs had seasonal variations, spatial distributions, sources, and composition profiles similar to those in ZJB seawater. By combining the cases of energy structure, residential and industrial layouts, maritime traffic, and activities related to ports and mariculture, this study concluded that PAHs in ZJB seawater are greatly influenced by land-based inputs, atmospheric deposition and human activities.

Simple multi-residue analysis of persistent organic pollutants and molecular tracers in atmospheric samples

We present a simple, selective and sensitive analytical method to quantitatively determine a wide range of halogenated persistent organic pollutants and molecular tracers in atmospheric samples. Identification and quantification was carried out by high-resolution gas chromatography, hyphenated with low-resolution mass spectrometry operating in electron impact (EI) and electron capture negative ionization (ECNI) mode. Optimization on a number of instrumental parameters was conducted to obtain ultra-trace detection limits, in the range of few fg/m³ for organohalogen compounds. Repeatability and reproducibility of the method was thoroughly evaluated. The analysis was validated with standard reference materials and successfully applied to actual atmospheric samples. The proposed multi-residue method provides a precise, affordable and practical procedure of sample analysis for environmental research laboratories with conventional instrumentation on a routine basis.•A simple combination of alumina, florisil and silica gel adsorbents was applied to sufficiently isolate polychlorinated biphenyls, organochlorine pesticides, polycyclic aromatic hydrocarbons, long chain n-alkanes, hopanes and steranes.•Full elution was achieved in two successive fractions, using small volumes of n-hexane and n-hexane/dichloromethane to recover all target substances.•To maximize analytical response, optimization was applied for three operating parameters in ECNI mode: i) ion source temperature; ii) emission current; and iii) electron energy.

Biomonitoring of atmospheric PAHs using fir and spruce needles in forests in the vicinity of mountain villages

The aim of the study was to use chemical analyses of spruce and fir needles to determine environmental exposure to polycyclic aromatic hydrocarbons (PAHs) in forests surrounding small mountain towns, including popular tourist destinations. The Beskid Mountains in Poland were chosen as the study area because they are very popular with tourists. The 6- and 12 month old needles were collected in two consecutive years from permanent study plots. Two vintages of needles were used to determine the differences between seasons in the profile of deposited pollutants. Some of plots were located away from roads and buildings, while others were located near tourist destinations. The comparison plots were located in the centre of a tourist resort, near a highway, and in a forest localised in the industrial city characterised by a high degree of urbanization. The analyses of 15 PAHs content showed that the amount and type of compounds retained by the needles were influenced not only by the proximity and amount of the surface emitters, but also by the location of the research sites above sea level. The results obtained can be explained, among other things, by the phenomenon of smog, which is not uncommon in the study region in autumn and winter.