Alkyl Polycyclic Aromatic Hydrocarbons Research Articles

Gas–particle partitioning and dry deposition of atmospheric parent, alkylated, nitrated and hydroxyl polycyclic aromatic hydrocarbons over the Bohai sea and northern Yellow sea in autumn

To elucidate the gas–particle partitioning characteristics and dry deposition contributions of polycyclic aromatic hydrocarbons (PAHs) in the marine environment, 23 integrated air samples were collected during a research cruise in the northern Yellow Sea (NYS) and Bohai Sea (BS) in mid-autumn 2020. The atmospheric concentrations of 23 parent PAHs (PPAHs), 18 alkylated PAHs (APAHs), five nitrated PAHs (NPAHs), and seven hydroxyl PAHs (OPAHs) in gaseous and particulate phases were measured simultaneously. The total concentrations of 53 PAHs varied from 8.77 to 348 ng/m3. The 2-ring and 3-ring PPAHs and APAHs had lower particle-bound fractions than those of the NPAHs and OPAHs. For the gas–particle partitioning of the PAHs, the gas–particle partitioning coefficients (Kp) estimated using an octanol–air partition coefficient (KOA)–based model and KOA/soot–air partition coefficient (KSA) dual model (KOA–KSA dual model) were lower than the Kp measured in the field. Underestimation of the Kp commonly occurred with these models, but the KOA–KSA dual model was more suitable than the KOA–based model for gas–particle partitioning of the 53 atmospheric PAHs in the BS and NYS. The estimated atmospheric dry deposition fluxes of the 53 PAHs ranged from 631 to 14,345 ng/m2/day. The BS receives a PAHs load of up to 117 tons/year. The study provides background information on the occurrence and environmental fate of PAHs and could be vitally important for environmental safety management for the Northwest Pacific Ocean.

Contamination Characteristics and Risk Assessment of Polycyclic Aromatic Compounds in Surface Dust of Suntuan Mining Area in Huaibei

The Suntuan mining area of Huaibei is a typical coal resource mining base in the Huainan-Huaibei areas in North China. Previous environmental studies related to surface dust in coal mining areas mainly focused on heavy metals and water-soluble ions, with little research on polycyclic aromatic compounds (PACs). In this study, gas chromatography-triple tandem quadrupole mass spectrometry (GC-MS/MS) was used to determine the contents of 16 parent polycyclic aromatic hydrocarbons (16PAHs), alkyl polycyclic aromatic hydrocarbons (aPAHs), and some oxygenated polycyclic aromatic hydrocarbons (OPAHs) in surface dust from the Suntuan mining area and surrounding environment. The results showed that the ΣPACs concentration range of surface dust in the Suntuan mining area was 283.8-36852.5 μg·kg-1 (mean:4114.2 μg·kg-1). ΣaPAHs (mean:2593.8 μg·kg-1) was 2.4 times higher than Σ16PAHs (mean:1074.9 μg·kg-1), which was the main contributor to PAC pollution. The composition of 16PAHs and aPAHs in surface dust was dominated by low molecular polycyclic aromatic hydrocarbons. The average OPAH content was 445.6 μg·kg-1. At the same time, PAC pollution was mainly concentrated around the mining area and near the road of a coal gangue landfill. Based on the positive matrix factor (PMF) analysis, it was inferred that the study area was mainly affected by petroleum sources, followed by coal and biomass combustion, and traffic sources and petroleum product leakage accounted for a relatively small proportion. Based on the ratio and distribution pattern of 16PAHs and aPAHs, it was inferred that when Σ16PAHs/ΣPACs<0.25, it was mainly polluted by the coal mining area. The results of PMF combined with lifetime carcinogenic risk (ILCR) showed that there were potential carcinogenic risks for children near the study area, mainly from coal and biomass burning and coal mining. There are many coal mining areas in Huaihe River Basin in China. The results of this study can provide reference for pollution prevention and control of PACs in these coal mining areas.

One-pot synthesis of a poly(styrene-acrylic acid) copolymer-modified silica stationary phase and its applications in mixed-mode liquid chromatography

As modified ligands with a wide range of sources, abundant functional groups, and good biocompatibility, polymers have been widely used in the development of silica-based chromatographic stationary phases. In this study, a poly(styrene-acrylic acid) copolymer-modified silica stationary phase (SiO2@P(St-b-AA)) was prepared via one-pot free-radical polymerization. In this stationary phase, styrene and acrylic acid were used as functional repeating units for polymerization and vinyltrimethoxylsilane (VTMS) was used as a silane coupling agent to link the copolymer and silica. Various characterization methods, such as Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), N2 adsorption-desorption analysis, and Zeta potential analysis, confirmed the successful preparation of the SiO2@P(St-b-AA) stationary phase, which had a well-maintained uniform spherical and mesoporous structure. The retention mechanisms and separation performance of the SiO2@P(St-b-AA) stationary phase in multiple separation modes were then evaluated. Hydrophobic and hydrophilic analytes as well as ionic compounds were selected as probes for different separation modes, and changes in the retention of the analytes under various chromatographic conditions, including different methanol or acetonitrile contents and buffer pH values, were investigated. In reversed-phase liquid chromatography (RPLC) mode, the retention factors of alkyl benzenes and polycyclic aromatic hydrocarbons (PAHs) on the stationary phase decreased with increasing methanol content in the mobile phase. This finding could be attributed to the hydrophobic and π-π interactions between the benzene ring and analytes. The retention changes of alkyl benzenes and PAHs revealed that the SiO2@P(St-b-AA) stationary phase, similar to the C18 stationary phase, exhibited a typical reversed-phase retention behavior. In hydrophilic interaction liquid chromatography (HILIC) mode, as the acetonitrile content increased, the retention factors of hydrophilic analytes gradually increased, and a typical hydrophilic interaction retention mechanism was inferred. In addition to hydrophilic interaction, the stationary phase also demonstrated hydrogen-bonding and electrostatic interactions with the analytes. Compared with the C18 and Amide stationary phases prepared by our groups, the SiO2@P(St-b-AA) stationary phase exhibited excellent separation performance for the model analytes in the RPLC and HILIC modes. Owing to the presence of charged carboxylic acid groups in the SiO2@P(St-b-AA) stationary phase, exploring its retention mechanism in ionic exchange chromatography (IEC) mode is of great importance. The effect of the mobile phase pH on the retention time of organic bases and acids was further studied to explore the electrostatic interaction between the stationary phase and charged analytes. The results revealed that the stationary phase has weak cation exchange ability toward organic bases and electrostatically repels organic acids. Moreover, the retention of organic bases and acids on the stationary phase was influenced by the analyte structure and mobile phase. Thus, the SiO2@P(St-b-AA) stationary phase could provide multiple interactions, as demonstrated by the separation modes described above. The SiO2@P(St-b-AA) stationary phase showed excellent performance and reproducibility in the separation of mixed samples with different polar components, indicating that it has promising application potential in mixed-mode liquid chromatography. Further investigation of the proposed method confirmed its repeatability and stability. In summary, this study not only described a novel stationary phase that could be used in RPLC, HILIC, and IEC modes but also presented a facile "one-pot" preparation approach that could provide a new route for the development of novel polymer-modified silica stationary phases.

Effects of Alkylation on Potency of Benz[a]anthracene for AhR2 Transactivation in Nine Species of Freshwater Fish.

Polycyclic aromatic hydrocarbons (PAHs) are naturally occurring or anthropogenic organic chemicals that can activate the aryl hydrocarbon receptor 2 (AhR2) and induce toxicity in fishes. Alkyl PAHs are more abundant than nonalkylated PAHs in certain environmental matrices and there is growing evidence that alkylation can increase potency, dependent on the position of alkylation. However, it is unknown if the effect of alkylation on potency is conserved across species. In addition, relatively little is known regarding the extent of interspecies variation in sensitivity to PAHs and alkyl PAHs. Therefore, objectives of the present study were to characterize potency of benz[a]anthracene (BAA) and three alkylated homologues representing different alkylation positions in nine phylogenetically diverse species of fish using a standardized in vitro AhR2 transactivation assay. BAA and each alkylated homologue activated the AhR2 in a concentration-dependent manner in each species. Position-dependent effects on potency were observed in every species, but these effects were not consistent across species. Interspecies variation in sensitivity to AhR2 activation by each PAH was observed and ranged by up to 561-fold. Alkylation both increased and decreased the range of interspecies variation and sensitivity, but the potency of each alkylated homologue relative to BAA ranged by less than an order of magnitude among species. These results represent an early step toward the consideration of alkylated homologues for more objective ecological risk assessments of PAHs to native fishes. Environ Toxicol Chem 2023;42:1575-1585. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Organic geochemical evidence of human-controlled fires at Acheulean site of Valdocarros II (Spain, 245 kya)

Among the outstanding questions about the emergence of human-controlled fire is the systematic recurrence between the geochemical remains of fire and its preservation in the archaeological record, as the use of fire is considered a technological landmark, especially for its importance in food cooking, defensive strategies, and heating. Here we report fossil lipid biomarkers associated with incomplete combustion of organic matter at the Valdocarros II site, one of the largest European Acheulean sites in Spain dated to marine isotopic stage (MIS) 8/7 (~ 245 kya) allowing a multiproxy analysis of human-controlled fire use. Our results reveal isolated cases of highly concentrated and diverse polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs (APAHs), along with diagnostic conifer-derived triterpenoids in two hearth-like archaeological structures. The presence of combustion byproducts suggests the presence of anthropogenic (controlled) fires at Valdocarros—one of the oldest evidence of fire use in Europe-in association with Acheulean tools and bones. Hominins possibly used fire for two main activities, as a means of defense against predators and cooking. Our results help to better delineate major gaps in our current knowledge of human-controlled fire in the context of the Middle-Pleistocene in Europe and suggest that human ancestors were able to control fire before at least 250 kya.

Parent and alkylated polycyclic aromatic hydrocarbon emissions from coal seam fire at Wuda, Inner Mongolia, China: characteristics, spatial distribution, sources, and health risk assessment.

The Wuda coalfield in Inner Mongolia is a vital coal base in China, and it is the hardest-hit area for coal fires (spontaneous combustion of coal seams and coal gangue). Using gas chromatography-mass spectrometry, this work tested the concentration and analyzed the characteristics, distribution, sources, and health risks of polycyclic aromatic compounds (PACs) in the surface soil of the Wuda District, including the coal mine, coal fire, agricultural, and background areas. The soil of coal mine and coal fire area were heavily polluted with PACs, with mean concentrations of 9107 and 3163µgkg-1, respectively, considerably higher than those in the agricultural (1232µgkg-1) and background areas (710µgkg-1). Alkyl polycyclic aromatic hydrocarbons (APAHs) were the dominant pollutants among these PACs, accounting for 60-81%. Alkyl naphthalenes and alkyl phenanthrenes are the primary pollutants in APAHs, accounting for 80-90% of the total amounts. Additionally, using the positive matrix factorization method, it can be concluded that the primary PAC sources are petrogenic sources, coal and biomass combustion, coal fires, and vehicle emissions. Finally, according to the cancer risk values of 16 PAHs, only the coal mine area showed a potential cancer risk. However, this result lacks a risk assessment of APAHs and underestimates the actual risk. The results of this study improved the understanding of PAC pollution in coal fire and surrounding areas and provided a reference for environmental and health risk investigations.

Contamination characteristics of polycyclic aromatic compounds from coal sources in typical coal mining areas in Huaibei area, China

The Huaibei area is rich in coal resources and serves as the main energy production base in East China. However, serious environmental consequences are associated with coal mining and utilization. With increasing reports on distribution and risks by polycyclic aromatic compounds (PACs), the potential pollution of coal sources must be addressed. Here, the PAC concentrations in the topsoil, coal, and coal gangue of a typical coal mining area in Huaibei were evaluated. The mean ΣPACs in topsoil, coal, and coal gangue were 1528.3, 274,815.8, and 10,908.3 μg·kg−1, respectively. Alkyl polycyclic aromatic hydrocarbons (aPAHs) were identified as primary contributors to PACs, and the concentrations of oxygenated PAHs (oPAHs) were significantly higher in coal and coal gangue than in topsoil. PAC pollution was mainly concentrated in the coal mine area and near the coal gangue landfill road. Not only sixteen high priority pollutant PAHs (16PAHs), but PAH derivatives also contributed to the organic pollution from coal sources. Principal components analysis, multiple linear regression, characteristic ratios, and positive matrix factor analysis were used to trace PAC sources. The characteristic ratios for organic pollution from coal and gangue particles involving 16PAHs, aPAHs, and oPAHs were proposed. Further, the high–ring 16PAH ratio was also found suitable for coal mining areas. The Monte–Carlo risk assessment showed that coal particles were highly carcinogenic, and despite the low carcinogenicity of coal gangue and topsoil, they might also serve as potential carcinogens. This study aimed to disseminate knowledge on PACs from coal and coal gangue, provide a useful background for efficient resource utilization of coal gangue, and a reference for tracing PAC sources in coal mine environment media.

Important But Overlooked Potential Risks of Substituted Polycyclic Aromatic Hydrocarbon: Looking Below the Tip of the Iceberg

Substituted polycyclic aromatic hydrocarbons (PAHs) are PAH derivatives in which substituents replace hydrogen atoms on the aromatic benzene ring, or N/S/O atoms replace carbon atoms in aromatic rings. Compared to unsubstituted PAHs, some substituted PAHs have higher pollution levels and more significant toxicity than their parent PAHs (p-PAHs), and the International Agency for Research on Cancer (IARC) lists them as possible human carcinogens, which harm human health but lack sufficient examination. This paper summarizes and discusses the environmental occurrence and distribution, toxicity, and impacts of substituted PAHs on human health and compares with the 16 representative priority-controlled PAHs (PAHs16). According to occurrence of PAHs in various environmental media, it is shown that the mean concentration of individual substituted PAH in the air is higher than that of individual PAH16. The mean concentration of individual substituted PAH in the soil varies widely among different countries, with a difference of 100,000 times between the lowest level (Italy) and the highest level (USA). The mean individual alkylated PAH (APAHs) and oxygenated PAH (OPAHs) are the most abundant in surface water and sediments. In the aspect of toxicity effects, some substituted PAHs have been proved to have similar or identical toxicity as PAHs16. We summarize existing problems and propose future priority research areas through the analysis of the occurrence and toxicity of substituted PAHs in the environment, which is important for further research and regulation of substituted PAHs.Graphical Abstract

Contamination characteristics and risk assessment of polycyclic aromatic compounds in soil from industrial park of Wuda District, Inner Mongolia, China

ABSTRACT Industrial Park of Wuda District is typical of industrial parks associated with coal bases in North China. Previous studies on this industrial park have focused mainly on inorganic components, such as mercury, fluorine, and water-soluble ions, with little research on polycyclic aromatic compounds (PACs). In this study, the contamination characteristics and potential health risks of alkyl polycyclic aromatic hydrocarbons (aPAHs) and 16PAHs in soil of the industrial park were examined. Under the combined influence of its own enterprises and the upwind coal fire area, the average concentration of ΣPACs was 10,176 μg·kg−1 and ranged from 177 to 42,794 μg·kg−1, exceeding the threshold for severe pollution. The average concentration of aPAHs was 7146 μg·kg−1, which was approximately twice that of the 16PAHs (3029 μg·kg−1). The parent 16PAHs were dominated by medium and high carbon rings, while the aPAHs were dominated by alkylnaphthalenes and alkylphenanthrenes. PACs were concentrated in areas of heavy polluting enterprises such as coal chemical industries and coal-fired power plants that generate point source pollution. Using the characteristic ratio method and positive matrix factorisation (PMF) analyses, it was inferred that the study area was mainly affected by petroleum sources (coal and weathered coal gangue particles) and coal fire residue, followed by wastes from coal and biomass combustion. Coal coking and transportation sources have had fewer impacts. Additionally, the toxicity levels of PACs in the soil of the industrial park exceeded regulatory thresholds. The incremental lifetime cancer risk (ILCR) was in the range of 1.0 × 10−7 to 1.7 × 10−5, indicating that the PACs in the industrial park pose a potential threat to human health. Owing to the presence of publicly accessible areas affected by coal mining, coal fire, and industrial parks in North China, the potential for widespread PAC pollution is worth consideration and investigation.

Alkylated Polycyclic Aromatic Hydrocarbons Are the Largest Contributor to Polycyclic Aromatic Compound Concentrations in the Topsoil of Huaibei Coalfield, China.

Alkyl polycyclic aromatic hydrocarbons (APAHs) are more toxic and persistent than their parent compounds. Here, the concentrations, composition profiles, and spatial distribution of polycyclic aromatic compounds (PACs) in 127 topsoil samples from Huaibei coalfield were analyzed. The PAC concentrations in different functional areas were significantly different: mining area > industrial area > residential area > agricultural area. APAHs were the major contributors to PACs, accounting for 71–83% of total PACs. Alkylnaphthalenes and alkylphenanthrenes were the primary APAH components, accounting for 83–87% of APAHs. Principal component analysis showed that petrogenic source, coal and biomass combustion, and vehicle emissions were the primary sources of PACs. By comparing the fingerprint information of soil, coal, and coal gangue, it was hypothesized that the petrogenic source of PAC pollution in typical mining areas and surrounding areas are coal particle scattering and coal gangue weathering. Some coal mining and industrial areas potentially pose risks to children, whereas others do not. There are limited evaluation criteria for alkyl PAHs; hence, the estimated risk is likely lower than the actual risk. In addition to the conventional 16 PAHs, it is critical to consider a broader range of PACs, especially APAHs.

Contamination characteristics of alkyl polycyclic aromatic hydrocarbons in dust and topsoil collected from Huaibei Coalfield, China.

Alkyl polycyclic aromatic hydrocarbons (APAHs) are more toxic and persistent than their parent compounds. In this study, the concentrations of polycyclic aromatic compounds (PACs) in dust, topsoil and coal gangue from Huaibei Coal mine, China were analyzed by gas chromatography-mass spectrometry, confirming APAHs were the dominant pollutants. The mean concentrations of APAHs were substantially higher than those of 16 PAHs in both dust and topsoil. The mean concentration of APAHs in dust was 9197µgkg-1, accounting for 80% of the total mean concentration of PACs. The mean concentration of APAHs in topsoil was 2835µgkg-1, accounting for 77% of the mean concentration of PACs. Alkyl naphthalenes and alkyl phenanthrenes were the primary pollutants in APAHs. Their mean concentrations in dust and topsoil were 7782µgkg-1 and 2333µgkg-1, respectively. This accounted for 85% and 82% of the concentration of APAHs, respectively. Additionally, low-molecular-weight APAHs dominated the PACs of the coal mine, exhibiting petrogenic characteristics; distribution of C1-C4 NAP and C1-C4 PHE exhibited "bell shape" pattern indicated as petrogenic source. Source identification indicated that the PACs were mainly derived from petrogenic sources and vehicle emissions, followed by biomass and coal burning. Fingerprinting information of dust and topsoil were consistent with coal gangue, indicating that PACs are most likely derived from coal gangue. Coalfields comparable to our study area are widely distributed in China. Therefore, investigating PAC pollution derived from coal gangue warrants further attention.

Growth of Sphingobium barthaii KK22 on 1-ethylnaphthalene reveals diverse oxidative transformations and a complex metabolite profile

Alkylated polycyclic aromatic hydrocarbons (APAHs) are major components of crude oils and petroleum-contaminated sediments and include the relatively water insoluble polyalkyl chain-alkylated PAHs (CA-PAHs). Little is known regarding CA-PAH transformation by microorganisms and therefore biodegradation pathways have not been established. Biotransformation of the CA-PAH 1-ethylnaphthalene (1-EN) by soil bacterium Sphingobium barthaii KK22 was investigated by gas chromatography and comprehensive liquid chromatography electrospray ionization tandem mass spectrometry analyses. 1-EN was utilized as a sole source of carbon and energy by strain KK22 and 200 mg/L of 1-EN as a nonaqueous phase liquid was depleted from culture media in approximately 5 days. 1-EN was oxidized through the aromatic rings, the alkyl moiety and through both the aromatic rings and the alkyl moiety resulting in a diverse metabolite profile that included different carboxylic acid metabolites and conjugation products. Transformation products were organized to construct the first extensive description of 1-EN transformation to the TCA cycle by a bacterium. Key biotransformation products such as 1-naphthoic acid and 3-ethylcatechol were identified and results of independent transformation assays using 1-methylnaphthalene and 1-naphthoic acid confirmed results from 1-EN assays. This work shows that sphingomonads may be versatile contributors to the reduction of CA-PAHs in contaminated environments.

Alkylation of Benz[a]anthracene Affects Toxicity to Early-Life Stage Zebrafish and In Vitro Aryl Hydrocarbon Receptor 2 Transactivation in a Position-Dependent Manner.

Polycyclic aromatic hydrocarbons (PAHs) are structurally diverse organic chemicals that can have adverse effects on the health of fishes through activation of aryl hydrocarbon receptor 2 (AhR2). They are ubiquitous in the environment, but alkyl PAHs are more abundant in some environmental matrices. However, relatively little is known regarding the effects of alkylation on the toxicity of PAHs to fishes in vivo and how this relates to potency for activation of AhR2 in vitro. Therefore, the objectives of the present study were to determine the toxicity of benz[a]anthracene and three alkylated homologs representing various alkylation positions to early life stages of zebrafish (Danio rerio) and to assess the potency of each for activation of the zebrafish AhR2 in a standardized in vitro AhR transactivation assay. Exposure of embryos to each of the PAHs caused a dose-dependent increase in mortality and malformations characteristic of AhR2 activation. Each alkyl homolog had in vivo toxicities and in vitro AhR2 activation potencies different from those of the parent PAH in a position-dependent manner. However, there was no statistically significant linear relationship between responses measured in these assays. The results suggest a need for further investigation into the effect of alkylation on the toxicity of PAHs to fishes and greater consideration of the contribution of alkylated homologs in ecological risk assessments. Environ Toxicol Chem 2022;41:1993-2002. © 2022 SETAC.

Emission Characteristics of Gas-and Particle-Phase Polycyclic Aromatic Hydrocarbons from Cooking

Polycyclic aromatic hydrocarbons (PAHs) play a key role in the formation of secondary organic areole and ozone. This study sampled three commercial Chinese restaurants and a food plant in Shenzhen to analyze the emission characteristics of PAHs, especially the alkyl PAHs in both gas and particle phases. The results showed that the ρ(total PAHs)in the particle and gas phase were (1381.6±140.5) ng·m-3, (1030.2±116.4) ng·m-3, (908.3±111.9) ng·m-3, and (838.0±93.5) ng·m-3 in the food plant, Sichuan, Cantonese, and Zhejiang restaurants, respectively. More than 60% of the PAHs were distributed in the gas phase, especially the lower molecular weight PAHs (lower than Chrysene). The gas phase proportion of naphthalene was the highest, with over 75% of it distributed in the gas phase. However, the PAHs with a higher molecular weight than that of benzo(b)fluorescence were mainly distributed in the particle phase. The total concentration of alkyl PAHs emitted from cooking was much lower than that of the corresponding parent PAHs, and the distribution characteristics of alkyl PAHs were quite different from those of other emission sources. The linear fitting of lgKp and lgPL showed that the slopes of the three commercial restaurants ranged from -0.25 to -0.28, whereas for the food plant, the value was -0.18, which indicates that the gas-particle partitioning of PAHs were not in equilibrium.

Quantitative Method of Alkyl Polycyclic Aromatic Hydrocarbons in Surface Soils of Coal Mines

Quantitative Method of Alkyl Polycyclic Aromatic Hydrocarbons in Surface Soils of Coal Mines

Chemical characterization of particulate organic matter from commercial restaurants: Alkyl PAHs as new tracers for cooking

Cooking is one of the primary sources of particulate organic matter (POM) in urban environments. Numerous experiments have been performed to investigate the composition of POM generated during cooking. However, there still remain substantial uncertainties in our knowledge regarding the emission characteristics of alkyl polycyclic aromatic hydrocarbons (PAHs) from cooking. In addition, previous studies have selected several tracers for Chinese cooking; however, these results were acquired based on observations in the Pearl River Delta region of China, and only four of the eight Chinese cooking styles were tested. Therefore, the organic compositions of the PM2.5 emitted from four Chinese cooking restaurants in different cities are examined to investigate the emission characteristics of alkyl PAH and to verify whether the selected tracers vary with geographical location and cooking styles. In this study, C1- and C2-phenanthrenes/anthracenes, and C1-pyrenes were detected in the PM2.5 from the four tested restaurants, but the concentrations of these PAH alkyl homologues were all at low levels, and also much lower than the corresponding parent PAHs. However, the distribution pattern of the alkyl PAHs in the cooking fumes was significantly different from that in the PM from other emission sources. Additionally, some candidate tracers for cooking such as levoglucosan were less influenced by cooking styles or geographical location. Thus, these alkyl PAHs in conjunction with other specific tracers for cooking were utilized to estimate the contribution of cooking to ambient organic carbon. The results showed that the estimates from the chemical mass balance model that includes alkyl PAHs will be higher than the model that does not, and in the case of high alkyl PAHs ambient concentrations, the model that includes alkyl PAHs will provide more reasonable results.

Selective dealkylation of alkyl polycyclic aromatic hydrocarbons towards innovative upgrading process of practical heavy oil

A silica-monolayer loaded on alumina with weak Brønsted acid sites and large pore size can selectively dealkylate alkyl polycyclic aromatics to long-chain alkanes and polycyclic aromatics for production of chemicals and fuel.

Prediction of octanol-water partition coefficients for alkyl-PAHs based on the solvation free energy

Octanol-water partition coefficients (KOW ) are of great importance in assessing the environmental fate and risk of hydrophobic organic pollutants including alkyl-polycyclic aromatic hydrocarbons (alkyl-PAHs). Due to the time-consuming and laborious of experimental determination of KOW , it is desirable to develop a rapid and accurate prediction model for the KOW of alkyl-PAHs. In this study, a prediction model for log KOW of alkyl-PAHs was developed according to the thermodynamic relationship between KOW and the solvation free energy from n-octanol phase to aqueous phase (ΔGOW ). ΔGOW values of alkyl-PAHs were calculated by the SMD model. The effect of dimer formation on the partition behaviour and partition coefficient was explored. After taking the effect of dimer formation into account, the goodness-of-fit, predictive ability, and robustness of the prediction model was significantly improved. The developed model in this study had the superiorities of universal application domain, low dependence on the experimental values and clear model mechanism.

Nontarget Screening of Polycyclic Aromatic Compounds in Atmospheric Particulate Matter Using Ultrahigh Resolution Mass Spectrometry and Comprehensive Two-Dimensional Gas Chromatography.

Polycyclic aromatic hydrocarbons (PAHs) are mutagenic and carcinogenic. 16 PAHs as priority pollutants listed by the US Environmental Protection Agency were usually monitored. Therefore, multiple potentially toxic polycyclic aromatic compounds (PACs) are not monitored. In this study, atmospheric particulate matter samples from Beijing were analyzed using atmospheric pressure photoionization (APPI) Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry and comprehensive two-dimensional gas chromatography-time-of-flight (GC × GC-TOF) mass spectrometry. The FT-ICR data detected high molecular weight PAHs, alkylated PAHs (APAHs) and heteroatom PAHs. The GC × GC-TOF data tentatively identified 386 PACs in five categories of identification confidence. Twenty-one spectra in the unknown class were manually resolved. Eighty-two PACs with high identification confidence were proposed for further research. The identities of five PAHs and five APAHs that are currently not regulated were confirmed using available standards and quantified in some samples. Some of these PACs, such as dibenzo[a,e]pyrene (C22H14) and 1-methylpyrene (C17H12), should be of concern because of their contamination levels and the high toxicities of themselves and/or their derivatives. This study highlights the possibility of expanding the traditional lists of PAHs to improve pollution control and risk assessment accuracy.

Bioprospecting of potential petroleum hydrocarbon degraders using bacterial strains isolated from soils around transformer installation areas

ABSTRACT The study assessed the contamination levels of the soils around transformer installation areas in Ile-Ife, which were contaminated with transformer oil. Contamination levels are determined by using some soil physicochemical properties (pH, electrical conductivity, and organic matter) and also identifying some hydrocarbon utilizing bacteria in the oil-contaminated soils. Soil samples were collected from transformer oil-contaminated and uncontaminated soils at 5−15-cm depth. Soil physicochemical properties were determined using standard methods. The soil samples were screened for hydrocarbon-degrading bacteria; the isolates were duly identified using the matrix-assisted laser desorption/ionization-time of flight/mass spectrometry technique. The growth rate of the bacterial isolates in the hydrocarbon medium was monitored. Thereafter, the residual oil was analyzed quantitatively and qualitatively using gravimetric and gas chromatography–mass spectrometry techniques, respectively. The results of the physiochemical parameters of the oil-contaminated soils showed that the soils had mean values of pH (5.01 ± 0.22), electrical conductivity (574.45 ± 63.35 µs/cm), and soil organic matter (50.53 ± 5.67 g/kg). The chromatogram of the residual oils from the biodegradation process showed the efficacy of Providencia stuartii and Bacillus pseudomycoides in degrading alkyl polycyclic aromatic hydrocarbons (PAHs), cycloalkanes, unsaturated alkanes, and unsaturated-branched alkanes, while Providencia rettgeri could adequately degrade cycloalkenes, cycloalkanes, unsaturated alkanes, and unsaturated-branched alkanes. In this study, novel hydrocarbon-degrading bacterial isolates were identified, and the extent of their hydrocarbon and complex organic compound utilization was shown, it suggests the need for further studies to explore their potentials in bioremediation programs.