Identification Of Polycyclic Aromatic Hydrocarbons Research Articles

Strong observational support for the [formula omitted] timeline in the early universe

JWST’s recent discovery of well-formed galaxies and supermassive black holes only a few hundred Myr after the big bang seriously challenges the timeline predicted by ΛCDM. Now, the latest identification of polycyclic aromatic hydrocarbons (PAHs) at z=6.71, together with these earlier inconsistencies, makes the time compression problem in this model quite overwhelming. We consider the timeline associated with the formation and growth of PAH grains based on current astrophysical models and argue that their appearance at z=6.71 favors the structure formation history in Rh=ct rather than that of Planck-ΛCDM. We estimate the time at which they must have started growing in each case, and then trace their history through various critical events, such as the end of the ‘dark ages’, the beginning of Pop III star formation, and the onset of reionization. Together, these three distinct discoveries by JWST, viz. high-z galaxies, high-z quasars and the surprisingly early appearance of PAHs, all paint a fully consistent picture in which the timeline in ΛCDM is overly compressed at z≳6, while strongly supporting the expansion history in the early Universe predicted by Rh=ct.

The Cosmic Timeline Implied by the JWST Reionization Crisis

JWST's discovery of well-formed galaxies and supermassive black holes only a few hundred Myr after the big bang, and the identification of polycyclic aromatic hydrocarbons (PAHs) at $z=6.71$, seriously challenge the timeline predicted by Lambda CDM. Moreover, the implied bright UV-irradiation of the early Universe suggests a reionization history much too short to comply with the observed evolution of the hydrogen ionization fraction, $x_ HII (z)$. A recent analysis of reionization after JWST by Munoz:2024 has concluded that the Lambda CDM timeline simply cannot accommodate the combined JWST- Planck observations even if exotic fixes are introduced to modify the standard reionization model. In this paper, we argue that this so-called `photon budget crisis' is more likely due to flaws in the cosmological model itself. We aim to re-analyze the data in the context of established astrophysics with $R_ h =ct$ as the background cosmology, an approach that has already been shown to mitigate the tension created by the too-early appearance of galaxies, quasars and PAHs. We employ the standard reionization model using the JWST-measured UV luminosity function in the early Universe and the timeline and physical conditions in both Lambda CDM and $R_ h =ct$. The former has already been fully probed and discussed by Munoz:2024 and we here merely redo the calculation to ensure consistency with their pioneering work. We then contrast the predicted reionization histories in these two scenarios and compare them with the data. We confirm that the reionization history predicted by Lambda CDM is in significant tension with the observations, and demonstrate that the latter are instead in excellent agreement with the $R_ h =ct$ timeline. Together, the four anomalies uncovered by JWST, including the newly discovered reionization `crisis' discussed in this paper, provide strong evidence against the timeline predicted by Lambda CDM and in favor of the evolutionary history in $R_ h =ct$.

One year of active moss biomonitoring in the identification of PAHs in an urbanized area—prospects and implications

Classical monitoring of air pollution provides information on environmental quality but involves high costs. An alternative to this method is the use of bioindicators. The purpose of our work was to evaluate atmospheric aerosol pollution by selected polycyclic aromatic hydrocarbons conducted as part of annual active biomonitoring (“moss-bag” technique) with the use of three moss species: Pleurozium schreberi, Sphagnum fallax, and Dicranum polysetum. The gas chromatography-mass spectrometry (GC–MS) was utilized to determine certain 13 polycyclic aromatic hydrocarbons (PAHs). Three seasonal variations in PAH concentrations have been observed as a result of the study. A fire on the toilet paper plant caused an increase of five new compounds: benzo(k)fluoranthene (BkF), benzo(a)pyrene (BaP), indeno(1.2.3)-cd_pyrene (IP), dibenzo(a.h)anthracene (Dah), and benzo(g.h.i)perylene (Bghi) in proximity after 8 months of exposure compared to previous months. The effect of meteorological conditions on the deposition of PAHs (mainly wind direction) in mosses was confirmed by principal component analysis (PCA). Dicranum polysetum moss accumulated on average 26.5% more PAHs than the other species, which allows considering its broader use in active biomonitoring. The “moss-bag” technique demonstrates its feasibility in assessing the source of PAH air pollution in a long-term study. It is recommended to use this biological method as a valuable tool in air quality monitoring.

Source identification of polycyclic aromatic hydrocarbons (PAHs) in soils around crude oil contaminated area in Ohaji/Egbema, Imo State

ABSTRACT This study aims to determine the source of polycyclic aromatic hydrocarbons (PAHs) in the soils surrounding an area in Ohaji/Egbema, Imo State, that has been contaminated by crude oil. Soil samples were collected in the study area using a soil auger at a depth of 0–20 cm at three sampling locations (sample A, sample B, and sample C) in the Mmahu community in Ohaji/Egbema. In each of the sampling locations, twenty sub-samples were collected from twenty sampling points and pooled together to form representative samples for each of the sampling locations. Prior to GC-MS analysis, the composite samples were air-dried, sieved through a 2-mm mesh, and then kept in pet bottles that had been previously cleaned. The GC-MS investigations were carried out using a Shimadzu Model 2010 GC-MS (Shimadzu, Japan) fitted with an HP-5 MS fused silica column. This was used to quantify the 16 USEPA priority PAHs in the studied soils. The sum of the 16 USEPA priority PAHs in the sample locations ranged from 0.0192 mg/kg in the control sample to 10.73 mg/kg in sample A. Compared to high molecular weight PAHs (4–6 rings), the total concentration of low molecular weight PAHs (2–3 rings) was found to be substantially greater. According to the PAH molecular diagnostic ratio, all sampling points had low to high molecular mass ratios >1, which suggests that the origin of the PAH contamination was petrogenic. The petrogenic source of contamination was attributed to oil spillage around the study area. The knowledge of source identification of PAHs in soils helps in the determination of the most appropriate remediation strategy in order to prevent further contamination and minimise the risks to human health and the environment.

Distribution and source identification of polycyclic aromatic hydrocarbons (PAHs) with PCA-MLR and PMF methods in the topsoil of Chengdu at SW, China

In spite of extensive studies on the features of polycyclic aromatic hydrocarbons (PAHs) as typical persistent organic pollutants (POPs) in cities, lack of understanding on the distribution and source characteristics of PAHs in big city with basin climate that can easily accelerate the pollution. Therefore, we sampled and analyzed PAHs from forty-five topsoil samples evenly distributed in Chengdu and the data shows that: (1) concentrations of ∑16PAHs in the study area ranged from 88.56 to 4448.34 ng/g, with a mean value of 739.07 ng/g, which is a lower level compared to similar cities, the distribution and proportion of LMW-PAHs show that the migration of pollution is blocked by the topography of the basin; (2) principal component analysis-multiple linear regression (PCA-MLR) and positive matrix factorization (PMF) indicated that combustion of fossil fuels and biomass is the most important source of PAHs in Chengdu; (3) the toxic equivalency factors of benzo[a]pyrene indicated a low risk of ∑16PAHs in all areas in Chengdu; (4) the inherited lifetime carcinogenic risk (ILCR) showed a relatively low level of potential risk in the region, while female inhabitants in several regions seem to suffer from higher health risks. Overall, our case study of PAHs in the topsoil at Chengdu city at SW China indicates that the PCA-MLR analysis is useful to identify the source of PAHs in the urban region with complicated pollution source.

Polycyclic aromatic hydrocarbons (PAHs) in coal preparation plant products: A contributor to environmental pollution

Coal and coal gangue are petrogenic sources of polycyclic aromatic hydrocarbons (PAHs), which cause adverse impacts on the environment. Raw coal, cleaned coal, slime, slack gangue, and lump gangue from the Pingshuo No. 1 Coal Preparation Plant, China, were analyzed to determine the concentrations and compositions of 16 priority parent PAHs (16PAHs) and their alkylated derivatives (aPAHs). The ∑16PAH and ∑aPAH concentrations in the samples ranged from 18.7 to 139.2 mg/kg and 22.2 to 262.3 mg/kg, respectively, and ranked as follows: cleaned coal > raw coal > slime > lump gangue > slack gangue. Coal gangues had a higher proportion and lower degree of alkylation of 4–6-ring PAHs than coals. A summary analysis of references related to coal and coal gangue diagnostic ratios showed that their ratios could not be used to differentiate them from other PAH sources, indicating that the release of particulate coal and coal gangue would increase the uncertainty of environmental PAH identification results. The diagnostic ratios of coal gangue were relatively concentrated, and comparing the ratio distribution could reveal the coal gangue source PAHs. The toxicity risk of slack gangue was higher than that of lump gangue based on the benzo[a]pyrene-equivalent concentration; hence, more attention should be given to its escape to the environment.

Characterization of scrubber water discharges from ships using comprehensive suspect screening strategies based on GC-APCI-HRMS

An extended suspect screening approach for the comprehensive chemical characterization of scrubber discharge waters from exhaust gas cleaning systems (EGCSs), used to reduce atmospheric shipping emissions of sulphur oxides, was developed. The suspect screening was based on gas chromatography coupled with high-resolution mass spectrometry (GC-HRMS) and focused on the identification of polycyclic aromatic hydrocarbons (PAHs) and their alkylated derivatives (alkyl-PAHs), which are among the most frequent and potentially toxic organic contaminants detected in these matrices. Although alkyl-PAHs can be even more abundant than parent compounds, information regarding their occurrence in scrubber waters is scarce. For compound identification, an in-house compound database was built, with 26 suspect groups, including 25 parent PAHs and 23 alkyl-PAH homologues. With this approach, 7 PAHs and 12 clusters of alkyl-PAHs were tentatively identified, whose occurrence was finally confirmed by target analysis using GC coupled with tandem mass spectrometry (GC-MS/MS). Finally, a retrospective analysis was performed to identify other relevant (poly)cyclic aromatic compounds (PACs) of potential concern in scrubber waters. According to it, 18 suspect groups were tentatively identified, including biphenyls, dibenzofurans, dibenzothiophenes and oxygenated PAHs derivatives. All these compounds could be used as relevant markers of scrubber water contamination in heavy traffic marine areas and be considered as potential stressors when evaluating scrubber water toxicity.

Improvements on the analysis methods of asphalt fumes generated in asphalt production and construction

Asphalt fumes are generated when producing and processing asphalt materials, and polycyclic aromatic hydrocarbons (PAHs) are commonly used as indicators to evaluate the hazardous potentials of asphalt fumes. However, the quantitative analysis of PAHs in asphalt fumes remains a challenge. Particularly, the influences of matrix compounds in asphalt fumes on PAH quantification have not been evaluated, even though matrix effect may lead to biased results. To address such a research gap, this study (1) examined the matrix effect in analyzing PAHs in asphalt fumes, (2) evaluated the effectiveness of clean-up methods, and (3) assessed the effectiveness of different methods for matrix effect compensation. Asphalt fumes from seven asphalt materials or conditions were collected and analyzed. Four clean-up methods were evaluated for their influences on PAH identification and matrix effect mitigation. Two approaches were experimented for matrix effect compensation. This study found an obvious matrix effect in the quantitative analysis of PAHs in asphalt fumes. None of the clean-up methods can effectively remove the matrix effect, but both the standard addition calibration (SAC) method and the internal standard calibration (ISC) method can compensate such effect. The findings are expected to assist in accurate quantification and evaluation of PAHs in asphalt fumes.

Synergistic cancer risk assessment from PM1 bound metals and PAHs in the Indo-Gangetic Region

The atmospheric particulate matter (PM) contains a significant amount of human carcinogens such as metals and Polycyclic Aromatic Hydrocarbons (PAHs). Previous studies have clearly shown that these carcinogens pose serious health issues due to the inhalation of particulate matter. Since the synergistic roles of these carcinogens are rarely considered, these studies frequently underestimate the health risk to humans. The current research aims to bridge this information gap by estimating the synergistic carcinogenic risk assessment owing to PM1 bound metals and PAHs across the densely populated Indo-Gangetic Plain (IGP). The carcinogenic risk assessment was conducted in accordance with the USEPA guidelines on these various PM1 bound components. The Incremental Lifetime Cancer Risk (ILCR) due to heavy metals, such as Lead (Pb) and Chromium (Cr), was found beyond the acceptable limit (> 10−4). The risk due to PM1 bound USEPA PAHs was also significantly higher (> 10−5). This study further estimated the potential toxicity from broad domain of environmental PAHs present in ambient air by considering relevant estimation factors from existing literature. The projected risk from these diverse environmental PAHs was of the order 10−4. Further, source identification of PAHs based on diagnostic isomer ratios revealed that diesel exhaust, biomass burning, and coal combustion are the dominant PAHs sources. Moreover, the exposure to these pollutants is higher in winter and post-monsoon periods. Overall, the synergistic carcinogenic risk found from metals and PAHs was of the order 10−3. In a nutshell, inhalation of PM1 bound heavy metals and PAHs at IGP can result in the development of 1000 cancer cases per million population, which is the highest value compared to other parts of the world. The present study demands immediate policy interventions not only for the reduction of particulate pollution, but also for the reduction of carcinogenic species from the ambient air in order to improve human health.

Methodical approaches to the detection polycyclic aromatic hydrocarbons in ambient air (analytical review)

Among the persistent organic pollutants of atmospheric air, a special place is occupied by a group of polycyclic aromatic hydrocarbons (PAHs) or polyarenes due to their high carcinogenic hazard. In view of the ubiquitous presence of these substances in the atmospheric air, low values of hygienic standards and values of reference concentrations (RfC) for chronic inhalation exposure, the qualitative and quantitative identification of PAHs is the critical task. Purpose is to analyze modern methodological approaches used in laboratory practice to determine polyarenes in atmospheric air on the base of Russian and foreign sources. The paper considers modern methods for the analytical control of PAHs in atmospheric air, officially approved in the Russian Federation and presented in the world literature. The search for literary sources was carried out using the PubMed, RSC Publishing, Springer Nature, SCOPUS, eLIBRARY.RU databases. An analysis of the methodological and scientific and technical literature on methods for the determination of PAHs in atmospheric air made it possible to identify the main directions of methodological developments used in modern laboratory practice for the analytical control of polyarenes in air. The advantages and disadvantages of specific methods, individual stages of analysis, conditions for sampling, storage and transportation of samples, which together can lead to false positive or false negative results, are presented. Conclusion. Modern methods for the analysis of polyarenes in atmospheric air are the result of continuous improvement in the technique of performing individual analytical procedures, the development of new methodological approaches to solving analytical problems, the emergence of new, more advanced measuring and auxiliary equipment, which makes it possible to develop highly sensitive and highly selective methods for measuring toxicants in the human environment at the level of MPCdaily average, MPCone-time and RfC for chronic inhalation exposure.

Polyaromatic Hydrocarbons (PAHs) present in aqueous ethanol, dichloromethane, and n-hexane extracts of Pumpkin (Cucurbita pepo) seed

The study evaluated the quantity of Polyaromatic hydrocarbon (PAH) present in aqueous ethanol (Aq. EtOH), dichloromethane (DCM), and n-hexane (n-hex) extracts of pumpkin (Cucurbita pepo) seed. Aliquots of dried extracts, gotten from the ground C. pepo, were subjected to Gas Chromatography Flame-Ionization Detector (GC-FID) analysis for quantitative identification of polycyclic aromatic hydrocarbons (PAHs) present in the samples. The procedure ensured that the analytical process had quality assurance and quality control. From the result, only naphthalene was present in all three samples (Aq. EtOH and DCM; 0.05ppm, n-hex.; 0.03ppm). Out of the eight (8) PAHs identified with potential carcinogenic effects by Environmental Protection Agency (EPA), only one, Fluorine, was present in only the n-hex extract (0.04ppm). From the result, DCM had more PAHs (5 PAHs) compared to n-hexane (4 PAHs) and Aq. EtOH (2 PAHs). The quantity of fluorine obtained from the extract is lower than the recommended daily intake in line with the European Union (EU) limits for fluorine, which is 0.05 ppm d-1 or mg kg−1 d−1. Owing to the fact that only one chemical compound of public health importance (on the EPA priority list) was found, which was far below the standard daily intake limit by calculation, it is safe to suggest that the C. pepo seed used in this study may pose minimal or no risk to exposed organisms. This study is important in investigating extracts intended for experimental purposes, for contaminants and other inherent compounds that may be noxious to the biological system.

Polycyclic Aromatic Hydrocarbons from Bottled Water: A New Automated Solid Phase Extraction Method and Simulation of Cancer Risk

Considering the adverse effects of polycyclic aromatic hydrocarbons (PAHs) on human health and the complexity of their detection in water resources, this study was developed to assess the performance of a new automated device for the identification of PAHs in water based on the solid-phase extraction and to simulate the cancer risk of 16 priority PAHs by Monte Carlo technique. All operational modes of extraction were automatically performed using the proprietary software program. Three spiked aliquots of PAHs including 100, 500, and 1000 ng/L were used to evaluate the performance of the automated-solid phase extraction (SPE) apparatus. The time of extraction in the automatic-SPE apparatus was 50±4 minutes for simultaneous extraction of 4 water samples, which was four times faster than that of manual-SPE apparatus. The mean recoveries of PAHs were 89.22±4.94, 91.70±4.45, and 94.61±6.28% in spiked samples, with a mean of 91.84±5.22%. Except for naphthalene, all obtained recoveries were in an acceptable range (85-115%). The results of Monte Carlo simulation showed that the cancer risk attributable to eight detected PAHs including naphthalene, fluorene, phenanthrene (Phe), benzoanthracene, chrysene, benzo(k) fluoranthene, indeno(cd)pyrene, and dibenzo(a,h)anthracene ranged from 0.05E-6 to 0.11E-6, with the cancer risk of 0.012E-6 having the highest probability (P=0.82). Additionally, this simulation showed that 99% of the probability density of cancer risk was located within the range lower than 0.05E-6. Our results showed that the novel automated-SPE apparatus could be utilized for the extraction of PAHs from water resources with a good recovery (85%-115%), high operational speed, and potential for separation of solvents from the air in the drying step. Therefore, this device can be used for the extraction of trace PAHs and similar organic compounds from water resources.

Shifts of the new functional marker gene (pahE) of polycyclic aromatic hydrocarbons (PAHs) degrading bacterial population and its relationship with PAHs biodegradation

Identification of polycyclic aromatic hydrocarbons (PAHs) degrading bacterial populations and understanding their responses to PAHs are crucial for the designing of appropriate bioremediation strategies. In this study, the responses of PAHs-degrading bacterial populations to different PAHs were studied in terms of the compositions and abundance variations of their new functional marker gene (pahE) by gene-targeted metagenomic and qPCR analysis. Overall, PAHs species significantly affected the composition and abundance of pahE gene within the PAHs-degrading bacteria in each treatment and different pahE of PAHs-degrading bacteria involved in the different stages of PAHs degradation. Noted that new pahE genotypes were also discovered in all PAHs treatment groups, indicating that some potential new PAHs-degrading bacterial genera were also involved in PAHs degradation. Besides, all three PAH removal rates were significantly positively related with pahE gene abundances (R2 = 0.908 ~ 0.922, p < 0.01), demonstrating that pahE could be a good indicator of PAHs degradation activity or potential. This is the first study focusing on the dynamic changes of the pahE gene within PAHs-degrading bacterial community during the degradation of PAHs in mangrove sediment, providing novel insights into the use of pahE gene as the functional marker to indicate PAH degradation.

Occurrences, Sources, and Human Health Risk Assessments of Polycyclic Aromatic Hydrocarbons in Marine Organisms From Temperate Coastal Area

The pollution characteristics of 16 polycyclic aromatic hydrocarbons (PAHs) in marine organism species (6 species of fishes and 2 species of crustaceans) from the coastal area of the East China Sea were determined. The concentrations of 16 PAHs in the studied organisms ranged from 29.73 to 87.02 ng/g dw and 2- and 3-ring PAHs were the most abundant compounds in the aquatic organisms. The habitat, diet and predator-prey relationship have posed potential effects on the PAH accumulation in marine organisms. The source identification of PAHs was performed by using the molecular diagnostic ratios and principal component analysis (PCA). The results showed that the main sources of PAHs in the marine organisms were coal combustion, followed by mixture of gasoline combustion, oil combustion, crude oil spill and vehicle emissions. The incremental lifetime cancer risk of human via ingestion process of marine organisms in this sea area was also estimated and the assessment showed that it posed an acceptable but non-negligible risk to human health.

Detection of polycyclic aromatic hydrocarbons using a high performance-single particle aerosol mass spectrometer

The real-time detection of the mixing states of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs in ambient particles is of great significance for analyzing the source, aging process, and health effects of PAHs and nitro-PAHs; yet there is still few effective technology to achieve this type of detection. In this study, 11 types of PAH and nitro-PAH standard samples were analyzed using a high performance-single particle aerosol mass spectrometer (HP-SPAMS) in lab studies. The identification principles ‘parent ions’ and ‘mass-to-charge (m/z) = 77’ of each compound were obtained in this study. It was found that different laser energies did not affect the identification of the parent ions. The comparative experiments of ambient atmospheric particles, cooking and biomass burning emitted particles with and without the addition of PAHs were conducted and ruled out the interferences from primary and secondary organics on the identification of PAHs. Besides, the reliability of the characteristic ions extraction method was evaluated through the comparative study of similarity algorithm and deep learning algorithm. In addition, the real PAH-containing particles from vehicle exhaust emissions and ambient particles were also analyzed. This study improves the ability of single particle mass spectrometry technology to detect PAHs and nitro-PAHs, and HP-SPAMS was superior to SPAMS for detecting single particles containing PAHs and nitro-PAHs. This study provides support for subsequent ambient observations to identify the characteristic spectrum of single particles containing PAHs and nitro-PAHs.

Source identification and health risk assessment of PAHs in surface soils from the vicinity of Arad-Kouh processing and disposal complex, Tehran, Iran

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) as ubiquitous pollutants can pose potential environmental and also human health risks. Therefore, this study was conducted for detecting, identifying the sources and evaluating the health risks of PAHs in topsoils in vicinity of Arad-Kouh processing and disposal complex, Tehran, Iran in 2020. In so doing, a total of 30 surface soil samples were collected from 10 sampling sites adjacent to Arad-kouh complex. After extraction of analytes, the gas chromatography/mass spectrometry (GC–MS) method was used to determine the rates of PAH compounds in surface soil samples. Based on the results obtained, the total concentrations (µg kg−1) of 16 PAHs ranged from 863 to 1384 with a mean of 1123. PAHs with 4–6 rings in their molecules with 65.3% of ∑16PAH mass dominated the PAH profiles. Molecular diagnostic ratios (MDRs) indicated that most of PAH compounds could originate from pyrogenic sources. The total incremental lifetime cancer risks (ILCRs) of PAH compounds with an average value of 4.20E-05 (ranging from 3.02E-05 to 5.23E-05), indicating a low potential carcinogenic risk of PAH compounds in the study area, especially through dermal contact. Although, the ILCRs values showed negligible adverse health effects from direct ingestion and inhalation of PAH compounds in the study area, regular and periodic monitoring of content and sources identification of PAHs in different environments and efforts to mitigate of their pollution for human health maintenance are recommended.

Seasonal trend and source identification of polycyclic aromatic hydrocarbons associated with fine particulate matters (PM2.5) in Isfahan City, Iran, using diagnostic ratio and PMF model.

Particulate matters (PMs) and their associated chemical compounds such as polycyclic aromatic hydrocarbons (PAHs) are important factors to evaluate air pollution and its health impacts particularly in developing countries. Source identification of these compounds can be used for air quality management. The aim of this study was to identify the sources of PM2.5-bound PAHs in Isfahan city, a metropolitan and industrialized area in central Iran. The PM2.5 samples were collected at 50 sites during 1year. Source identification and apportionment of particle-bound PAHs were carried out using diagnostic ratios (DRs) of PAHs and positive matrix factorization (PMF) model. The results showed that the concentrations of PM2.5 ranged from 8 to 291μg/m3 with an average of 60.2 ± 53.9μg/m3, whereas the sum of concentrations of the 19 PAH compounds (ƩPAHs) ranged from 0.3 to 61.4ng/m3 with an average of 4.65 ± 8.54ng/m3. The PAH compounds showed their highest and lowest concentrations occurred in cold and warm seasons, respectively. The mean concentration of benzo[a]pyrene (1.357ngm-3) in December-January, when inversion occured, was higher than the Iranian national standard value showing the risk of exposure to PM2.5-bound PAHs. Applying DRs suggested that the sources of the PAHs were mainly from fuel combustion. The main sources identified by the PMF model were gasoline combustion (23.8 to 33.1%) followed by diesel combustion (20.6 to 24.8%), natural gas combustion (9.5 to 28.4%), evaporative-uncombusted (9.5 to 23.0%), industrial activities (8.4 to 13.5%), and unknown sources (2.8 to 15.7%). It is concluded that transportation, industrial activities, and combustion of natural gas (both in residential-commercial and industrial sectors) as the main sources of PAHs in PM2.5 should be managed in the metropolitan area, particularly in cold seasons.

Sources and composition of chemical pollution in Maritime Antarctica (King George Island), part 1: Sediment and water analysis for PAH sources evaluation in the vicinity of Arctowski station

The paper presents a study regarding the identification of polycyclic aromatic hydrocarbons (PAHs) in fresh waters and surface sediments on the western shore of Admiralty Bay over four sampling seasons from 2017 to 2018. The results were compared to literature data from 2016 to provide a more comprehensive image of the environmental fate of PAHs over the years. The highest value of Σ PAHs was 82.9 ng/L and 445 ng/g dw in water and sediment samples, respectively. The analysis of PAH indicator ratio values showed that pyrogenic or mixed sources contribute to the PAH pollution in Antarctic sediments and water more than does petroleum. The main source is the combustion of biomass (e.g. as a result of fires) and coal, and PAHs are mostly associated with the activity of stations or are transported to a lesser extent by long-range atmospheric transport (LRAT) from South America. The values of the ΣLMW/ΣHMW ratio in sediments indicate that petrogenic sources contribute to PAH contamination, but among the six PAH ratios tested, petrogenic sources were identified as dominant in approximately 17–19% of cases. Lack of coherence in the obtained results confirms the mixed origin of PAHs in the studied samples. Although the differentiation of PAHs sources is still ambiguous, caution is recommended in light of the Antarctic system's evident and rapid response to global and local PAH emissions, and the dependency of accumulation and release cycle processes on weather conditions. A reduction in petrol usage in favour of renewable energy sources, and restriction of tourism are strongly recommended for better preservation of the pristine Antarctic environment.

Environmental occurrence, spatial distribution, and source identification of PAHs in surface and groundwater samples of Abou Ali River-North Lebanon

This paper assesses the concentrations, spatial distribution, compositional patterns, and sources of polycyclic aromatic hydrocarbons (PAHs) in the dissolved aqueous phase along the Abou Ali River course. The 16 priority PAHs, listed by the USEPA, were investigated in surface- and groundwater samples for 2years starting August 2015 and ending in March 2017. Statistical analysis was done by using the ANOVA test at p < 0.05. The spatial distribution analysis and illustration were done using the ARC GIS software. The total PAHs concentration in surface and groundwater samples varied between not detected to 15.162ngmL-1 and not detected to 0.635ngmL-1, respectively. The highest concentration of PAHs in surface water was observed at site S16, downstream of the river. However, the absence of PAHs was noticed at sites S1 and S2 of the upstream. The contamination levels of PAHs were found to be high in surface water samples, and low in groundwater samples. The 5- and 6-ring PAHs were the most abundant species among others in surface water samples, whereas the 3-ring PAHs were the most abundant in groundwater. Pyrogenic inputs deriving from fuel combustion, incineration, and miscellaneous burning were found to be the main PAH sources in surface and groundwater without ignoring the contribution of petrogenic inputs in some areas.

Emission characteristics and source identification of polycyclic aromatic hydrocarbons (PAHs) from used mineral oil combustion

Presently, the characteristic of hazardous polycyclic aromatic hydrocarbons (PAHs) emission from used mineral oil (UMO) combustion in the industrial scenario is poorly explored and elucidated. In this work, the emission characteristic and source identification of 16 PAHs emitted from atomization combustion of five kinds of UMO and two types of base oil were investigated. The influence of temperature (600–1000 °C) and excess air ratio (0.8–1.4) on PAHs emission were assessed. Regarding emission factor (EF) and distribution of specific PAHs, high similarities were observed for combustion of different UMOs. EFs of PAHs were within the range between 61.58 µg g−1 and 105.03 µg g−1 (800 °C, stoichiometric air). The 2- and 3-ring PAHs made up more than 70% of the total PAHs in the flue gas, with the naphthalene accounting for 30.7%–48.1%. Over 80% of the emitted PAHs was partitioned into gas phase. The EFs of PAHs showed a parabolic trend with temperature and peaked at 800 °C. Higher temperature can decrease the total PAHs emission but lead to the enrichment of high-ring PAHs. Adequate air supply can efficiently reduce PAHs formation, especially at high temperatures. More than 95% of the total PAHs was eliminated when the excess air ratio was increased from 0.8 to 1.4 at 900 °C. Temperature influence on PAHs emission can be greatly weakened in high excess air level. The PAHs emitted from UMO combustion were randomly irrelevant to the original PAHs in UMO.