Polycyclic Aromatic Compounds Research Articles

Bioaccessible PAH influence on distribution of antibiotic resistance genes and soil toxicity of different types of land use.

For a better understanding of the dissemination of antibiotic resistance genes (ARGs) in natural microbial communities, it is necessary to study the factors influencing it. There are not enough studies showing the connection of some pollutants with the dissemination of ARGs and especially few works on the effect of polycyclic aromatic compounds (PAHs) on the spread of resistance in microbiocenosis. In this respect, the aim of the study was to determine the effect of bioaccessible PAHs on soil resistome. The toxicity and the content of bioaccessible PAHs and ARGs were studied in 64 samples of soils of different types of land use in the Rostov Region of Russia. In most soils, a close positive correlation was demonstrated between different ARGs and bioaccessible PAHs with different content of rings in the structure. Six of the seven studied ARGs correlated with the content of 2-, 3-, 4-, 5- or 6-ring PAHs. The greatest number of close correlations was found between the content of PAHs and ARGs in the soils of protected areas, for agricultural purposes, and in soils of hospitals. The diverse composition of microbial communities in these soils might greatly facilitate this process. A close correlation between various toxic effects identified with a battery of whole-cell bacterial biosensors and bioaccessible PAHs of various compositions was established. This correlation showed possible mechanisms of PAHs' influence on microorganisms (DNA damage, oxidative stress, etc.), which led to a significant increase in horizontal gene transfer and spread of some ARGs in soil microbial communities. All this information, taken together, suggests that bioaccessible PAHs can enhance the spread of antibiotic resistance genes.

Experimental and numerical investigation of soot growth and inception in an ammonia-ethylene flame

The effect of ammonia (NH3) addition on soot growth and inception is investigated in laminar co-flow NH3-ethylene (C2H4) diffusion flames. By comparing C2H4 flames with increasing% of NH3 by volume for the same carbon flow and flame height, the impact of NH3 addition on soot formation is identified. Experimental measurements of flame temperature, soot volume fraction, and primary particle sizes and number densities are compared with a numerical two-dimensional co-flow flame model to evaluate the contribution of NH3 to soot reduction in C2H4 flames. Experimental and numerical results show a significant reduction in the amount of soot formed and the diameter and the number of the primary particles suggesting reduced rates of soot growth and inception due to NH3 addition. The numerical model provides the understanding of how NH3 inhibits soot formation in the flame by analyzing the soot formation pathways and investigating the concentration of relevant gas phase species in the flame. While the impact of NH3 addition on the growth of soot particles is not fully captured by the model, the NH3’s reductive effect on the number of soot particles formed is well predicted. The results suggest that NH3 reduces soot by suppressing the concentration of methyl radicals which are responsible for forming odd numbered carbon species such as propargyl and cyclopentadiene. These species are found to be important contributors to the formation of large polycyclic aromatic compounds which are precursors of soot inception.

Interaction of Polycyclic Aromatic Hydrocarbon compounds in fish primary hepatocytes: From molecular mechanisms to genotoxic effects

Polycyclic Aromatic Hydrocarbons (PAHs) are persistent pollutants normally found in the environment as complex mixtures. Although several individual PAHs are classified as mutagenic and carcinogenic pollutants, the interaction effects between compounds in a mixture may trigger different toxicological mechanisms and, consequently, yield different effects to organisms which are not accounted for in risk assessment guidelines. Given the ubiquity of PAHs, understanding the mechanistic features of their mixtures is a pressing research need. Therefore, the present work aimed to disclose the interaction effects of three PAHs with different carcinogenic potential and chemical structure, in primary hepatocyte cells of gilt-headed seabreams (Sparus aurata). Hepatocytes were exposed to Phenanthrene (Phe), Benzo[a]pyrene (B[a]P) and Benzo[b]fluoranthene (B[b]F) and their mixtures at different proportions and several cellular responses were analyzed: cellular viability, CYP1A1 activity (EROD assay) and protein expression level (Western blot); transcript (mRNA) levels of CYP1A1, EPXH1 and GST-3 (qRT-PCR); genotoxic effects (DNA strand breakage) by the Comet assay. Results show that B[a]P induced CYP1A1 gene and protein expression increasing its activity and, therefore, increasing the production of metabolites that trigger genotoxic DNA damage (%). Most importantly, mixtures containing Phe and B[a]P increased even further CYP1A1 mRNA levels and DNA damage (up to 70 %) which suggests that, although Phe is considered a non-carcinogenic PAH, it potentiates CYP1A1 synthesis induced by B[a]P, increasing its genotoxicity. These findings indicate that the upregulation of CYP1A1 by carcinogenic PAHs will not weaken even when in mixtures with non-carcinogenic PAHs. On contrary, non-carcinogenic PAHs may potentiate the genotoxic effect of carcinogenic PAH and therefore mixture composition should be taken in account when assessing PAH toxicity. In fact, our results point to the need of redefining Environmental Risk Assessment protocols for mixtures of carcinogenic pollutants.

Investigation of the maturation effects on biomarker distributions in bituminous coals

Biomarkers in coal can evolve dramatically in terms of their concentration and distribution during coalification, limiting their use in source allocation of coal-derived pollution. Here we analyzed a broad range of aliphatics (i.e., 26 n-alkanes, 6 isoprenoids, 32 terpanes, 19 steranes) and 77 polycyclic aromatic compounds (PACs) in the Permo-Carboniferous and Late Triassic coals from the Chinese Huainan and Da Baoding coalfields, respectively. These coals, classifying as high volatile bituminous B to low volatile bituminous with vitrinite reflectance (Rr) values ranging from 0.71 to 1.74 %, show variable organic geochemical features owing to the combined effects of thermal maturity and organofacies. Changes in the n-alkanes and isoprenoids indicate the loss of aliphatic fractions associated with maturation owing to cracking of the long-chain alkanes. The stratigraphic changes in the pristane to phytane ratios (Pr/Ph), Pr/n-C17, and Ph/n-C18 reflect a control exerted by the depositional environment in the Huainan coals. In addition, principal component analysis (PCA) recognizes the Pr/n-C17, Ph/n-C18, carbon preference index (CPI), and odd-to-even predominance 2 (OEP 2) as organofacies sensitive indices. Intercomparison of the PAC distributions suggest different maturation pathways for the coals from the Huainan and Da Baoding coalfields. The demethylation processes related to coalification preferentially occur on the polymethyl substitutes that occur to a greater degree in the Da Baoding coals than in the Huainan coals. Nine PAC indices display distinctive patterns when plotting against Rr. The DMP-2 vs DBT:DBF cross-plot explicitly separates the Huainan and Da Baoding coals into three distinctive zones representing different depositional environments and sources of organic matter. Moreover, PCA explicitly discriminate the maturation sensitive indices (i.e., MNR, DNR-1, TrMN-1, TrMN, TeMN, MPR, and MPI-1) from organofacies sensitive indices (i.e., DMP-2 and DBT:DBF).

Combustion of crude oil during in-situ burning can introduce polycyclic aromatic compounds (PACs) into small-scale freshwater systems

In-situ burning (ISB) is the controlled combustion of an oil slick to remove large quantities of spilled oil from the aquatic environment. Prior to employing ISB as a remediation technique, an oil slick must often be corralled by physical or chemical means to achieve a sufficient thickness (typically >1 mm) for ignition. While ISB is an effective means to remove oil mass, less is known about the potential for ISB to mobilize polycyclic aromatic compounds (PACs) into the aquatic environment. The PACs are primary contaminants of concern in crude oil due to their environmental persistence and toxicity. We examined the potential for ISB to mobilize PACs into underlying waters in a series of small-scale burns conducted across a gradient of oil slick thicknesses (0–7 mm). Concentrations of PACs in underlying waters were evaluated and compared to reference conditions using an equivalent gradient of oil slick thicknesses that were not ignited. At thinner slick thicknesses (i.e. 0 – 4 mm) ISB enhanced the mobilization of total PACs, likely a result of heat transfer to underlying waters; this effect increased as slick thickness increased. Among thicker slicks (i.e. 4 – 7 mm), pyrogenic PACs became more prevalent and greater concentrations of 4-ring PACs were detected in underlying waters. The potential for PAC mobilization needs to be considered in scenarios where ISB may be the only viable oil spill remediation option (e.g. wetlands, marshes, or where oil is entrained) and in shallow systems susceptible to temperature changes.

Even allocation of benefits stabilizes microbial community engaged in metabolic division of labor.

Microbial communities execute metabolic pathways to drive global nutrient cycles. Within a community, functionally specialized strains can perform different yet complementary steps within a linear pathway, a phenomenon termed metabolic division of labor (MDOL). However, little is known about how such metabolic behaviors shape microbial communities. Here, we derive a theoretical framework to define the assembly of a community that degrades an organic compound through MDOL. The framework indicates that to ensure community stability, the strains performing the initial steps should hold a growth advantage (m) over the "private benefit" (n) of the strain performing the last step. The steady-state frequency of the last strain is then determined by the quotient of n and m. Our experiments show that the framework accurately predicts the assembly of our synthetic consortia that degrade naphthalene through MDOL. Our results provide insights for designing and managing stable microbial systems for metabolic pathway optimization.

INNOVATION OF BARRACUDA (Sphyraena sp.) CHIKUWA WITH MICROENCAPSULATION LIQUID SMOKE ADDITION IN SUPPORTING SDG's GOAL 2

Chikuwa is a product made from surimi, then grilled over fire. The result of roasting gives a smoked flavor to chikuwa. Smoke flavor can be obtained not only through the combustion process, which can produce Polycyclic Aromatic Hydrocarbon compounds. In order to support the implementation of SDG's goal 2, microencapsulated coconut shell liquid smoke can be used as a flavoring agent in barracuda chikuwa to replace the combustion process. The purpose of this study was to determine the effect of the addition of microencapsulated liquid smoke on the characteristics of barracuda chikuwa to support SDG's goal 2. The experimental laboratory research method uses a Completely Randomized Design. The research was conducted by producing microencapsulated liquid smoke and barracuda chikuwa. The test results showed that the use of microencapsulated liquid smoke with different concentrations had a significant effect on all test parameters (p< 0,05). The highest phenol content was 0,1085% and the highest antioxidant was 69,65%. The lowest water content was 51, 2% and the lowest TPC value was 3.36 log cfu/g. While the results showed the highest protein content was 17, 69% and the highest hardness was 450.75 gf. Based on the assessment of the hedonic test, the highest value was obtained by the addition of 1% microencapsulated liquid smoke, with a value of 8,39 < µ < 8,71. The addition of microencapsulated liquid smoke was able to increase the protein, phenol, antioxidant, and hardness levels of barracuda chikuwa, as well as reduce the water content and TPC value.

N-Alkanes and Polycyclic Aromatic Hydrocarbons in Deposition Dust and PM10 of Interiors in Touggourt Region, Algeria.

The occurrence of pollutants in environment displays its maximum impact on human health and on the global "quality" of life in the places where humans spend most of their time, i.e., indoors. A field study was undertaken in the region of Touggourt, Algeria. The goal was that of obtaining information on the main sources of indoor pollutant emissions (n-alkanes and polycyclic aromatic compounds) associated with deposition dusts (DDs) and suspended particulates (PM10). A multi-service clinic, two schools, a coffee bar, three houses, and an asphalt distribution center were investigated. Forty-five samples in total were collected, including 31 deposition dusts and 14 airborne particulates. That would improve the current understanding of pollution features in central Algeria reached through previous investigations in the Touggourt region. Capillary gas chromatography coupled with mass spectrometric detection was adopted to determine the concentrations of n-alkanes and PAHs. In deposition dust, total n-alkanes (TNAs) ranged between 37 and 794ng/(m2 day) in the summer and 33-1,724ng/(m2 day) in the fall. Meanwhile, TNAs loads in the PM10 samples ranged between 778 and 2,024ng/m3. According to Carbon Preference Index (CPI), Cmax, and wax n-alkanes (WaxCn) approaches, both DD and PM10 were released overall by anthropogenic sources, though the contribution of natural emissions could not be neglected. Total polycyclic aromatic hydrocarbons (TPAHs) associated with DD ranged from 4.4ng/(m2 day) to 127ng/(m2 day) during the summer period, and 2.0-224ng/(m2 day) in the fall; TPAHs' concentrations in PM10 ranged between 40ng/m3 and 984ng/m3. Preliminary information about the sources of PAHs was drawn by calculating the concentration ratios between diagnostic pairs (DRs) of PAHs. According to PAH DR values, the pollution sources influenced at distinct extents all of the sites and locations investigated. Anyway, the PAH occurrence was associated with petrogenic sources, with the prevalence of gasoline fuel cars, at most sites. A wide variability was also observed by comparing the concentrations of pollutants observed in the summer and in the fall. This was in agreement with the results of n-alkanes emissions.

Wetting Properties of Clathrate Hydrates in the Presence of Polycyclic Aromatic Compounds: Evidence of Ion-Specific Effects

Polycyclic aromatic hydrocarbons (PAHs) have attracted remarkable multidisciplinary attention due to their intriguing π–π stacking configurations, showing enormous opportunity for their use in a variety of advanced applications. To secure progress, detailed knowledge on PAHs’ interfacial properties is required. Employing molecular dynamics, we probe the wetting properties of brine droplets (KCl, NaCl, and CaCl2) on sII methane–ethane hydrate surfaces immersed in various oil solvents. Our simulations show synergistic effects due to the presence of PAHs compounded by ion-specific effects. Our analysis reveals phenomenological correlations between the wetting properties and a combination of the binding free-energy difference and entropy changes upon oil solvation for PAHs at oil/brine and oil/hydrate interfaces. The detailed thermodynamic analysis conducted upon the interactions between PAHs and various interfaces identifies molecular-level mechanisms responsible for wettability alterations, which could be applicable for advancing applications in optics, microfluidics, biotechnology, medicine, as well as hydrate management.

Swirling Flame Combustion of Heavy Fuel Oil Blended with Diesel: Effect of Asphaltene Concentration

Heavy fuel oil has an energy density content comparable to distillate fuels but a very high viscosity that necessitates extra heating before spray combustion inside a boiler. Heavy fuel oil is also characterized by high asphaltenes, carbon residues, trace metals, such as vanadium and nickel, fuel-bound nitrogen, and sulfur. Asphaltenes are heavy polycyclic aromatic compounds with embedded heteroatoms and significantly affect the physico-chemical properties of heavy fuels; this makes them very difficult to burn and leads to the formation of large cenospheres (lightweight, inert, hollow spheres), due to an inefficient burning process. The primary goal of this study is to experimentally investigate the influence of the asphaltene concentration on the combustion of HFO under a swirling flame, finally reducing gaseous and solid pollution. We tested HFO samples containing asphaltene concentrations of 4, 6, 8, 16, and 24 wt.%, prepared by blending the light oil of diesel and pure asphaltenes with HFO. This work provides quantitative information about the effect of different asphaltene contents on the fuel properties of viscosity, density, heating value, thermogravimetry with air and N2, and swirling flame combustion characteristics, including the analysis of gaseous and solid particle emissions. The results indicated that the high asphaltene content in the fuel was the critical factor for the high viscosity and incomplete combustion and also increased the density of the fuel sample. Reducing the asphaltene content in HFO improves its spray characteristics and combustion performance and reduces the solid emissions containing sulfur and metal elements.

Extensive chemical and bioassay analysis of polycyclic aromatic compounds in a creosote-contaminated superfund soil following steam enhanced extraction

Polycyclic aromatic compounds (PACs) are organic compounds commonly found in contaminated soil. Previous studies have shown the removal of polycyclic aromatic hydrocarbons (PAHs) in creosote-contaminated soils during steam enhanced extraction (SEE). However, less is known about the removal of alkyl-PAHs and heterocyclic compounds, such as azaarenes, and oxygen- and sulfur-heterocyclic PACs (OPACs and PASHs, respectively). Further, the impact of SEE on the freely dissolved concentration of PACs in soil as well as the soil bioactivity pre- and post-SEE have yet to be addressed. To fulfil these research gaps, chemical and bioanalytical analysis of a creosote-contaminated soil, collected from a U.S. Superfund site, pre- and post-SEE were performed. The decrease of 64 PACs (5–100%) and increase in the concentrations of nine oxygenated-PAHs (OPAHs) (150%) during SEE, some of which are known to be toxic and can potentially contaminate ground water, were observed. The freely dissolved concentrations of PACs in soil were assessed using polyoxymethylene (POM) strips and the concentrations of 66 PACs decreased post-SEE (1–100%). Three in vitro reporter gene bioassays (DR-CALUX®, ERα-CALUX® and anti-AR CALUX®) were used to measure soil bioactivities pre- and post-SEE and all reporter gene bioassays measured soil bioactivity decreases post-SEE. Mass defect suspect screening tentatively identified 27 unique isomers of azaarenes and OPAC in the soil. As a remediation technique, SEE was found to remove alkyl-PAHs and heterocyclic PACs, reduce the concentrations of freely dissolved PACs, and decrease soil bioactivities.

Detection of Nitrated, Oxygenated and Hydrogenated Polycyclic Aromatic Compounds in Smoked Fish and Meat Products.

Polycyclic aromatic hydrocarbons (PAHs) are present in smoked food products. More toxic nitrated (NPAH) and oxygenated (OPAH) PAHs derivatives are found concomitantly to PAHs and are therefore believed to be found in smoked food products. However, only a few PAH analyses on food include these derivatives. We adjusted and successfully validated a GC-QTOFMS method including 13 NPAHs and 2 OPAHs as well as the 4 regulated PAHs for analysis of 14 smoked (13 fish and one bacon) and one pan fried fish samples.OPAHs were detected in the highest concentrations in 13 of 15 samples. Non-target screening revealed the presence of an additional four OPAHs and two methylated PAHs. Future food analysis should, based on these results, focus on PAH and oxygenated derivatives.

S-Shaped Fused Azacorannulene Dimer: Structural and Redox Properties

S-Shaped Fused Azacorannulene Dimer: Structural and Redox Properties

Furan-Containing Chiral Spiro-Fused Polycyclic Aromatic Compounds: Synthesis and Photophysical Properties.

Spiro-fused polycyclic aromatic compounds (PACs) have received growing interest as rigid chiral scaffolds. However, furan-containing spiro-fused PACs have been quite limited. Here, we design spiro[indeno[1,2-b][1]benzofuran-10,10′-indeno[1,2-b][1]benzothiophene] as a new family of spiro-fused PACs that contains a furan unit. The compound was successfully synthesized in enantiopure form and also transformed to its S,S-dioxide derivative and the pyrrole-containing analog via aromatic metamorphosis. The absorption and emission properties of the obtained furan-containing chiral spiro-fused PACs are apparently different from those of their thiophene analogs that have been reported, owing to the increased electron-richness of furan compared to thiophene. All of the furan-containing chiral spiro-fused PACs were found to be circularly polarized luminescent materials.

Characteristics of particle-bound polycyclic aromatic hydrocarbons (PAHs) in indoor PM2.5 of households in the Southwest part of Ulaanbaatar capital, Mongolia

Air pollution, including PM2.5 concentration in Ulaanbaatar (capital of Mongolia) is a serious matter of concern. As the majority of households use coal in large areas of the city, indoor air quality is also posing a serious risk to human health. This study investigated the concentration of polycyclic aromatic compounds (PAHs) in indoor particulate matter (PM2.5) in 10 non-smoker households. Sampling was conducted in winter of 2018, between 27 January and 09 February. Concentrations of PM2.5 in the indoor air of households ranged between 62.8 and 324.8 µg m−3. Total concentration of PAHs also varied in a relatively wide range, between 46.2 and 175.7 ng m−3. Five-ring PAHs represented a considerably high fraction of total PAHs between 25 and 53%, benzo[b]fluoranthene (BbF) and benzo[a]pyrene (BaP) were the two predominant compounds within five-ring PAHs. Significant correlation was found between indoor and outdoor particulate matter levels in wintertime. Considering individual characteristic PAHs, heavier PAHs homologues (4- to 5-ring and 6-ring PAHs) were detected in all households, which suggested the influence of coal combustion and traffic exhaust. Health risk of children attributed to PAHs inhalation was assessed by taking into account the lifetime-average daily dose (LADD) and corresponding lifetime cancer risk. Lifetime average daily dose for children in only one household were slightly higher than health-based guideline level (1.0 × 10−5), defined by WHO, whereas LADD for adults and children of other households were within acceptable limit. The cancer risks from the exposure of children to air pollutants in all households except HH-3 were found high. In the Vibrio fischeri bioluminescence inhibition assay, according to the toxic unit (TU) values of indoor PM2.5 from ten households, all samples were classified as toxic.

Histology study and transcriptome analysis of the testis of Loach(Misgurnus anguillicaudatus) in response to phenanthrene exposure

Phenanthrene (PHE) is one of the most abundant polycyclic aromatic hydrocarbon compounds (PAHs) in the aquatic environment. The loaches were exposed at concentrations of 0.30、1.00、3.00 mg L−1 for 60 days. The effects of PHE on the testis development were evaluated by calculating the survival rate, observing the structure of testis and analyzing transcriptome. Firstly, PHE markedly decreased the survival rate in a dose-dependent manner. Then, the number and density of spermatogonia, primary spermatocytes, secondary spermatocytes and spermatids were substantially reduced under PHE exposure. The space in the seminiferous tubule obviously increased in the high PHE concentration group. Meanwhile, transcriptome comparative analysis identified 5329 differentially expressed genes (DEGs) including 2928 up-regulated and 2401 down-regulated in the testis of loach exposed PHE for 60 days. Meiotic cell cycle, arganelle fission, ATPase activity and adenylate nucleotide binding were significantly differences by GO (Gene Ontology) enrichment. KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis revealed that TNF (Tumor Necrosis Factor) signaling pathway, CAMs (Cell Adhesion Molecules), cytochrome P450 and lipid metabolism were markedly regulated. In addition, eight DEGs were randomly selected from the testis transcriptomics results for qPCR verification, the results were consistent with RNA-Seq. Finally, related genes (piwil2, dmc1, vasa, ubr2, dnd, rnf17, plcb2, c-fos, gpx4) of testis development were further confirmed and they were differentially regulated after PHE exposure. In summary, a survey of the mechanism of loach testis response to PHE was performed, and a large number of gene expression levels regarding metabolism, spermatogenesis and immunity genes were acquired from RNA-seq. This study provide informations for elucidating the molecular mechanism of PHE affected the testis development of loach.

Vertical distribution characteristics and interactions of polycyclic aromatic compounds and bacterial communities in contaminated soil in oil storage tank areas.

Polycyclic aromatic compound (PAC) contamination in soil as a result of oil spills is a serious issue because of the huge global demand for fossil energy. This study assessed the vertical variation in polycyclic aromatic hydrocarbons (PAHs), derivatives of PAHs (dPAHs) and bacterial community structure in deep soil with long-term contamination by oil spillage. Our results suggest that the content of total PACs ranged from 1196.6μg/kg to 14980.9μg/kg and decreased with depth at all sites. PAHs were the most abundant PACs, with a mean concentration of 6640.7μg/kg, followed by oxygenated PAHs (mean 156.3μg/kg) and nitrated PAHs (mean 33.4μg/kg). PAHs are mainly low molecular weight PACs such as naphthalene, fluorene and phenanthrene, while derivatives of PAHs are all low molecular weight PACs and mainly oxygenated PAHs. Low molecular weight PAHs were an important source of dPAHs under specific conditions. The bacterial community structure showed higher bacterial diversity and lower bacterial richness in shallow soil (2-6m in depth) than in deep soil (8-10m in depth). Spearman's analysis confirmed that dramatic bacterial community shifts are a response to contamination. At the genus level, the presence of PACs highly selected for Pseudomonas, belonging to Proteobacteria. Moreover, functional predictions based on Tax4Fun revealed that soil with long-term contamination had a strong potential for PAC degradation. In addition, statistical analysis showed that oxidation-reduction potential (Eh) was closely related to variations of bacterial community composition and function. Finally, Ramlibacter, Pseudomonas, Pseudonocardia, c_MB-A2-108, f_Amb-16S-1323, and Qipengyuania were identified by cooccurrence network analysis as keystone taxa contributing to the maintenance of bacterial ecological function. Together, our results provide evidence of tight bacterial effects of PAHs and dPAHs and a more complete understanding of the fate of PACs in deep contaminated soils.

Treatment of phenols and NH3–N with activated carbon and polyurethane carrier in biological enrichment reactor

Coal pyrolysis wastewater contains a large number of phenols, ammonia, and various monocyclic and polycyclic aromatic compounds. In the study, activated carbon (AC) or polyurethane (PU) suspension carriers were comprehensively compared from efficiency, influencing factors, extracellular polymeric substances, and microbial population distribution to explore the suitable carrier in biological enrichment reactor the treatment of coal pyrolysis wastewater. In the start-up stage, the treatment effect of COD and total phenol (TPh) in the PU group (COD 86%, TPh 75%) was lower than that of the AC group (COD 94%, TPh 88%). However, with the loading of biofilm on PU, the treatment effects in the PU group began to improve. When COD was approximately 1000 mg/L and TPh was 500 mg/L, both the AC group and PU group showed sound treatment effects on COD (≥87%) and TPh (∼99%). Moreover, the PU group showed a higher removal effect of NH3–N (32.22%) and TN (30.85%). HRT should be 24 h to ensure partial degradation of organic matter and save carbon source dosage of the subsequent A/O treatment unit. Moreover, it had a removal effect on NH3–N and TN, which could effectively reduce the load of the subsequent multistage A/O treatment unit. The dominant functional bacteria in the AC and PU groups included Acidovorax, Alicycliphilus, Chryseobacterium, Rhodanobacter, and Thermomonas. Acidovorax, Alicycliphilus, and Chryseobacterium were the main functional bacteria involved in TPh and COD degradation. AC was suitable for rapidly reducing the concentration of pollutants or dealing with sudden increases in pollutants, while PU was more conducive to the long-term and stable operation of the biological enrichment reactor.

Alkylated Polycyclic Aromatic Compounds in Road Runoff Are an Environmental Risk and Should Be Included in Future Investigations.

Polycyclic aromatic compounds (PACs) and metals are important contaminants in road runoff. Vital mitigation measures against aquatic contamination from road runoff include the use of sedimentation ponds. However, it has been demonstrated that ecosystems in sedimentation ponds might be affected by road runoff. Sediments from six natural ponds and 27 sedimentation ponds were investigated to determine the environmental risk of contaminants. The amount of traffic on the respective roads associated with the sedimentation ponds was correlated with the environmental concentrations. Quantification included seven metals, the 16 US Environmental Protection Agency polycyclic aromatic hydrocarbons, alkylated PACs, dibenzothiophene, benzo[e]pyrene, and perylene. The environmental risk was assessed according to the European Union Water Framework Directive guidelines. Sedimentation ponds had a higher level of contaminants than natural ponds, and environmental risks were dominated by the concentration of PACs. Alkylated PACs contributed to the environmental risk posed by PACs and should be included in future monitoring. Only Cu and Zn were measured at concentrations above the environmental quality standards (EQSs), while 13 PACs exceeded the EQS. Sediment concentrations of Cu, Zn, and most PACs correlated significantly with the amount of traffic. The sources of PACs were determined by source apportionment ratios between PACs. Alkylation and pyrogenic indices showed that sources in natural ponds were of mostly pyrogenic origin, whereas in sedimentation ponds they were predominantly petrogenic. Asphalt was the probable main source of PACs. A hierarchical clustering technique was used to investigate both the environmental risks and the pattern of PACs in the ponds and revealed that a few sedimentation ponds were not protecting the environment as intended because the upper sediment layers had not been regularly dredged. Environ Toxicol Chem 2022;41:1838–1850. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Effect of benzo[a]pyrene on proliferation and metastasis of oral squamous cell carcinoma cells: A transcriptome analysis based on RNA-seq.

Benzo[a]pyrene (BaP), a representative polycyclic aromatic hydrocarbon compound, is a carcinogen that causes head and neck cancers. Despite intensive research, the molecular mechanism of BaP in the development of oral squamous cell carcinoma (OSCC) remains largely unknown. In the present study, the SCC-9 human OSCC cell line was cultured in vitro, separated into treatment groups, and treated with dimethyl sulfoxide or BaP at various concentrations. The malignant behavior ascribed to the BaP treatment was investigated by cell proliferation, clony formation assay, and Transwell assays. Furthermore, transcriptome sequencing was performed to detect the differentially expressed genes, followed by quantitative real-time PCR to measure the expression levels of nine of these genes. Moreover, the Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed the biological processes and signaling pathways in which the target genes were involved. Significant effects on SCC-9 cell proliferation, tumorigenicity, cell migration, and invasion were observed after exposure to 8μM BaP. Additional results revealed that BaP inhibited apoptosis in a dose-dependent manner. The transcriptome sequencing results showed 137 upregulated genes and 135 downregulated genes induced by BaP, associated with tumor-related biological processes and signaling pathways, mainly including transcriptional dysregulation in cancer, the tumor necrosis factor signaling pathway, metabolism of xenobiotics by cytochrome P450, mitogen-activated protein kinase signaling pathway, and so forth. Our study demonstrates that BaP may regulate the expression of certain genes involved in tumor-associated signaling pathways, thereby promoting the proliferative, tumorigenic, and metastatic behaviors of OSCC cells while suppressing their apoptosis.