Absence Of Polycyclic Aromatic Hydrocarbons Research Articles

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.

Chemical profiling of liposoluble liquid smokes obtained from Eucalyptus wood tar: confirmation of absence of polycyclic aromatic hydrocarbons

ABSTRACT Liposoluble liquid smoke (LS) preparations are versatile food additives used worldwide. The objective of the present work was to characterise the chemical composition of four types of industrial liposoluble LS currently used as the basis for the production of commercial smoke flavourings. The LS was obtained by vacuum fractional distillation from a raw pyrolysis oil (raw LS) obtained primarily from eucalyptus wood tar. The raw LS and the four LS flavourings obtained therefrom were analysed by gas chromatography/mass spectrometry (GC/MS) to characterise the main groups of components. Additional analyses were carried out to evaluate the occurrence of PAHs (polycyclic aromatic hydrocarbons) in the samples, as the producer claimed that these samples are free of PAHs. The main chemical components characterised in the LS were organic acids, aldehydes, esters, furans, pyrans and phenols, with phenolic compounds being the major chemical group. For the four LS tested samples, no PAHs could be detected with the method employed, which could indicate that the industrial processing was able to effectively remove this harmful class of compounds, or at least decrease its concentrations to levels below the limits of detection of the method of analysis.

Variations of the composition of PAHs and the ratio of carbon and nitrogen in the soils of Batagaika thermoerosive carter in Northern Yakutia

Polycyclic aromatic hydrocarbons (PAHs) are the ubiquitous organic pollutants. They are formed as a result of incomplete oxidation of organic substance, for example, technogenic fuel combustion, heating system, wildfires, volcanism, and decomposition of organic residues. Special attention is given to pyrogenic factor of the formation of PAHs in soils. The subject of this research is PAHs in the soils of Batagaika thermoerosive carter in Northern Yakutia in Verkhoyansky Ulus in Yakutia. The author examines the peculiarities of two soil sections (indices B-VG-2019/1 and B-VG-2019/3). Both soils are post-pyrogenic and contain visible traces of a recent fire: embers are found in subsurface horizons of the examined sections, which indicate the recent fire. The following conclusion were formulated: 1) in soils, dicyclic PAHs account for 93%, while the proportions of tricyclic and tetracyclic compounds are roughly equivalent (4% and 3%, respectively); 2) the average values of individual PAHs in the upper (up to 30 cm) and lower (deeper than 30 cm) horizons differ. In the upper horizons, their total concentration is 27 ng/g, while in the lower horizons it is 14 ng/g; 3) in this case, the key biomarker of fires is naphthalene and its homologues. The absence of PAHs with considerable molecular weight most likely testifies to the relatively low fire intensity. The highest values of C/N ratio are noted in the bedding horizon: 10.89 and 3.31, and the lower soils are characterized with approximately 1, which is substantiated by the low content of carbon and nitrogen in the soil profile.

Enhanced degradation of polycyclic aromatic hydrocarbons (PAHs) in the rhizosphere of sudangrass (Sorghum × drummondii)

Grasses are advantageous in the removal of polycyclic aromatic hydrocarbons (PAHs) in soil because of their fibrous root, high tolerance to environmental stress, and low nutritional requirements. In this study, a pot experiment was conducted to test the ability of four grasses to remove PAHs in the soil, and to investigate the corresponding bacterial community shift in the rhizosphere of each. Sudangrass achieved the maximum removal of PAHs at 98% dissipation rate after 20 days. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and next-generation sequencing revealed that sudangrass specially enriched the growth of a known PAHs degrader, Sphingomonadales, regardless of the presence or absence of PAHs in the soil. Moreover, the gene copy numbers of PAHs catabolic genes, PAH-RHDα and nidA, as measured by real time-PCR (RT-PCR) were highest in the soil planted with sudangrass. Overall, this study suggested that sudangrass further enhanced the dissipation of PAHs by enriching Sphingomonadales in its rhizosphere.

Simulation and experimental study of FET biosensor to detect polycyclic aromatic hydrocarbons

Abstract In this paper, the DNA/Cu2O-GS nanostructure was simulated to detect polycyclic aromatic hydrocarbons (PAHs) and compared with our experimental results. We use a simulation for calculations based on density functional theory (DFT). In the first step, DNA/Cu2O-GS nanostructure was simulated and adsorption mechanism, the density of states and charge transfer process were investigated in the presence and absence of PAHs using the QUANTUM ESPRESSO software and BoltzTrap computing code. The simulation results showed that Cu2O-GS nanostructure can be well used to adsorption and stabilization of DNA. Also the simulation results of electrical conductivity change showed that DNA/Cu2O-GS nanostructure can be well used as a field effect transistor (FET) to detect PAHs. On the other hand, the electric current changes of the DNA/Cu2O-GS-FET for three samples of PAHs (benzene, toluene, and naphthalene) were experimentally studies. Also current leakage, the sensitivity, and dynamic range of transistor for benzene, naphthalene and toluene experimentally were investigated. The experimental results show that the DNA/Cu2O-GS-FET can use as a biosensor for PAHs. Our simulation and experimental results are in good agreement and this DFT-based simulation idea can use for other biosensors.

Acknowledgement of Referees 2015

The entire process of power generation, extraction, processing and use of coal strongly impact water resources, soil, air quality and biota leads to changes in the fauna and flora. Pollutants generated by coal burning have been contaminating plants that grow in area impacted by airborne pollution with high metal contents. Baccharis trimera is popularly consumed as tea, and is widely developed in Candiota (Brazil), one of the most important coal burning regions of the Brazil. This study aims to investigate the phytochemical profile, in vivo genotoxic and mutagenic potential of extracts of B. trimera collected from an exposed region to pollutants generated by coal burning (Candiota City) and other unexposed region (Bagé City), using the Comet assay and micronucleus test in mice and the Salmonella/microsome short-term assay. The HPLC analyses indicated higher levels of flavonoids and phenolic acids for B. trimera aqueous extract from Bagé and absence of polycyclic aromatic hydrocarbons for both extracts. The presence of toxic elements such as cobalt, nickel and manganese was statistically superior in the extract from Candiota. For the Comet assay and micronucleus test, the mice were treated with Candiota and Bagé B. trimera aqueous extracts (500–2000 mg/kg). Significant genotoxicity was observed at higher doses treated with B. trimera aqueous extract from Candiota in liver and peripheral blood cells. Micronuclei were not observed but the results of the Salmonella/microsome short-term assay showed a significant increase in TA98 revertants for B. trimera aqueous extract from Candiota. The extract of B. trimera from Candiota bioacumulated higher levels of trace elements which were associated with the genotoxic effects detected in liver and peripheral blood cells.

Chemical and toxicological effects of medicinal Baccharis trimera extract from coal burning area

The entire process of power generation, extraction, processing and use of coal strongly impact water resources, soil, air quality and biota leads to changes in the fauna and flora. Pollutants generated by coal burning have been contaminating plants that grow in area impacted by airborne pollution with high metal contents. Baccharis trimera is popularly consumed as tea, and is widely developed in Candiota (Brazil), one of the most important coal burning regions of the Brazil. This study aims to investigate the phytochemical profile, in vivo genotoxic and mutagenic potential of extracts of B. trimera collected from an exposed region to pollutants generated by coal burning (Candiota City) and other unexposed region (Bagé City), using the Comet assay and micronucleus test in mice and the Salmonella/microsome short-term assay. The HPLC analyses indicated higher levels of flavonoids and phenolic acids for B. trimera aqueous extract from Bagé and absence of polycyclic aromatic hydrocarbons for both extracts. The presence of toxic elements such as cobalt, nickel and manganese was statistically superior in the extract from Candiota. For the Comet assay and micronucleus test, the mice were treated with Candiota and Bagé B. trimera aqueous extracts (500-2000 mg/kg). Significant genotoxicity was observed at higher doses treated with B. trimera aqueous extract from Candiota in liver and peripheral blood cells. Micronuclei were not observed but the results of the Salmonella/microsome short-term assay showed a significant increase in TA98 revertants for B. trimera aqueous extract from Candiota. The extract of B. trimera from Candiota bioacumulated higher levels of trace elements which were associated with the genotoxic effects detected in liver and peripheral blood cells.

Ca2+ Promoted the Low Transformation Efficiency of Plasmid DNA Exposed to PAH Contaminants

The effects of interactions between genetic materials and polycyclic aromatic hydrocarbons (PAHs) on gene expression in the extracellular environment remain to be elucidated and little information is currently available on the effect of ionic strength on the transformation of plasmid DNA exposed to PAHs. Phenanthrene and pyrene were used as representative PAHs to evaluate the transformation of plasmid DNA after PAH exposure and to determine the role of Ca2+ during the transformation. Plasmid DNA exposed to the test PAHs demonstrated low transformation efficiency. In the absence of PAHs, the transformation efficiency was 4.7 log units; however, the efficiency decreased to 3.72–3.14 log units with phenanthrene/pyrene exposures of 50 µg·L–1. The addition of Ca2+ enhanced the low transformation efficiency of DNA exposed to PAHs. Based on the co-sorption of Ca2+ and phenanthrene/pyrene by DNA, we employed Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and mass spectrometry (MS) to determine the mechanisms involved in PAH-induced DNA transformation. The observed low transformation efficiency of DNA exposed to either phenanthrene or pyrene can be attributed to a broken hydrogen bond in the double helix caused by planar PAHs. Added Ca2+ formed strong electrovalent bonds with “–POO––” groups in the DNA, weakening the interaction between PAHs and DNA based on weak molecular forces. This decreased the damage of PAHs to hydrogen bonds in double-stranded DNA by isolating DNA molecules from PAHs and consequently enhanced the transformation efficiency of DNA exposed to PAH contaminants. The findings provide insight into the effects of anthropogenic trace PAHs on DNA transfer in natural environments.

Roadside, Urban, and Rural comparison of size distribution characteristics of PAHs and carbonaceous components of Beijing, China

Size-segregated aerosol samples were collected with a low-pressure impactor (LPI) at urban, roadside and rural sites in winter in Beijing. The size distribution of Polycyclic Aromatic Hydrocarbons (PAHs), organic carbon (OC) and elemental carbon (EC) were measured and this study focused on their size distributions and relationships of PAH to OC/EC. All PAHs show uni-modal at the accumulation mode (0.1–1.8 μm) and almost all PAHs are associated with fine particles. The absence of PAHs in the nucleus mode contributes to the coagulation under the condition of high concentration of the accumulation mode particles. The absence of PAHs in the coarse mode was probably attributed to the low temperature that restrained the redistribution of PAHs from the accumulation mode to the coarse mode. Flu(fluoranthene) and Pyr(pyrene, 4-ring) were the most abundant particulate PAHs ; however, IcdP(indeno[1,2,3-cd]pyrene) and BghiP(benzo[ghi]perylene, 6-ring) were rather low. Diagnostic ratios show vehicle and coal burning were the major sources of PAHs in winter. Ratios at rural site are obviously different from those found at roadside and urban sites. Lower value of OC/EC in the rural area than that in the urban area was probably resulted from coal burning prevailed in the rural area. OC1 and OC2 exhibit uni-mode distribution similar to their particle surface area distribution indicating their existence on particles by adsorption. OC3 and OC4 show bi-mode distribution. Grinding of biomass debris can be a probable source of OC3 and OC4 in the coarse mode. EC1 is mostly from the pyrolysis of OC; however, both the natural and anthropogenic emissions contribute to EC2. The correlation between size-segregated PAHs and carbonaceous component is also discussed to identify their sources.

On the early-time chemistry in dark clouds

Context. Agreement between observed and calculated abundances of some molecules in dark clouds is improved when the model gas retains some memory of the assumed initial conditions. Aims. We assess the relevance of commonly-assumed intitial conditions giving rise to so-called early-time chemistry in models of dark cloud chemistry. Methods. Initial conditions for models of dark cloud chemistry are compared with conditions known to exist in the H2-bearing diffuse gas whose evolution they are intended to represent. Results. The initial conditions assumed for dark cloud chemistry differ in at least five important regards from those of H2-bearing diffuse gas. Models typically assume: absolute purity of H2; absence of polycyclic aromatic hydrocarbons; two times smaller gasphase abundance of C, N, and O; near-absence of sulfur and some other easily-ionized metals; total absence of the molecules which accompany the presence of H2 in diffuse gas, for instance, OH, CH, C2H, HCO + . Conclusions. Initial conditions commonly assumed for dark cloud chemical models should be reconsidered and mechanisms for the chemical evolution from diffuse to dark gas should be included in model calculations.

UPTAKE OF FOUR PAHS OCCURRING INTO AERIAL PLANT TISSUE ARTIFICIALLY EXPOSED TO HEAVY FUEL OIL IN SALICORNIA

ABSTRACT Coastal salt-marsh vegetations are directly exposed to accidental marine pollution by oil spill, as it was the case in winter of the year 2000 following Erika tanker oil spill in France. As petroleum is incorporated in sediment, it tends to coat aerial parts of plants. Among fuel hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) are the most toxic compounds known in marine organisms. Although their low water solubility, they can be taken up and bioaccumulated by plants. This work was conducted to determine whether PAHs, like naphthalene, phenanthrene, pyrene and benzo(a)pyrene, present in artificially fuel contaminated soils are transferred or not to aerial part of the coastal and edible plant, Salicornia fragilis. Sediments were mixed up with N°6. heavy fuel oil. Young plants of Salicornia were sampled in spring at the “Aber du Conquet” (Finistère, France), and cultured artificially in three different mixture conditions of oil and sediment: 0.2%, 2% or 20%. Two durations of culture were tested: one or five weeks. At the end of the culture, shoot are then cut off and PAHs concentrations were determinate by (GC-MS). Results showed that whatever the time of exposure and the concentrations of fuel oil in soil, significant PAHs concentrations were measured in Salicornia tissues. Phenanthrene and pyrene are the most abundant compounds. The particular morphology of Salicornia plants and the absence of PAHs in control also suggest that root uptake was the main pathway for accumulation of PAHs in this halophytic plant. By this capacity to uptake PAHs from fuel oil contaminated soil, Salicornia fragilis appears as a potential bioindicator of marine pollution by petroleum and may have a role in remediating contaminated soil.

Inhibition of Sarcoplasmic/Endoplasmic Reticulum Calcium ATPases (SERCA) by Polycyclic Aromatic Hydrocarbons in HPB-All Human T Cells and Other Tissues

Polycyclic aromatic hydrocarbons (PAHs) are immunosuppressive chemicals found in the environment that have been shown to disrupt intracellular Ca2+ homeostasis and Ca(2+)-dependent signaling in human and murine lymphocytes. Many PAHs produce a rapid and sustained increase in intracellular free Ca2+ in lymphocytes. The mechanism of persistent Ca2+ perturbation remains undefined. In the present studies, ATP-dependent 44Ca2+ uptake into vesicles prepared from a 15,000g supernatant of HPB-ALL human T cell lysates was significantly inhibited by 0.1, 1, and 10 microM concentrations of the immunotoxic PAHs 7,12-dimethylbenz[a]anthracene (DMBA), benzo[a]pyrene (BAP), benz[a]anthracene, and 9,10-dimethylanthracene, but not by the less immunotoxic compounds anthracene (ANT) and benzo[e]pyrene (BEP). Ca(2+)-ATPase catalytic activity was determined by quantitating hydrolysis of ATP in the presence or absence of PAHs, with known ATPase inhibitors included as controls. Formation of inorganic phosphate was significantly decreased (> 65% of control at 10 microM) by DMBA and BAP, whereas ANT and BEP caused only a slight reduction in activity (10% of control at 10 microM). Anthracene partially reversed the inhibitory effect of DMBA and BAP on ATP hydrolysis when agents were coincubated. Both DMBA and BAP, but not ANT and BEP, inhibited the activity of all known SERCA-type Ca(2+)-ATPases, while not affecting either Na+, K(+)-ATPase activity or plasma membrane Ca(2+)-ATPase activities. These results demonstrate that immunotoxic and carcinogenic polycyclic aromatic hydrocarbons have a thapsigargin-like effect in human lymphocytes and SERCA-containing tissues from various species. Inhibition of SERCA activity may play an important role in altered Ca2+ homeostasis in lymphocytes and other tissues.

Polycyclic aromatic hydrocarbons in Australian coals. I. Angularly fused pentacyclic tri- and tetraaromatic components of Victorian brown coal

Analysis of the tri- and tetraaromatic hydrocarbon fractions of a brown coal sample from the Latrobe Valley, Victoria, Australia indicate the predominance of pentacyclic hydroaromatic components. Many of these have not been previously reported in the literature, but are obviously diagenetically related to triterpenoids naturally occurring in the biosphere. The components whose molecular structures have been confirmed, together with those for which tentative structural assignments are given, offer strong support for a theory of progressive diagenetic aromatization of C-3 oxygenated triterpenoids, commencing from ring A. Other compounds present in smaller amounts suggest that 1,2-methyl shift reactions also occur prior to or during aromatization. There is a notable absence of polycyclic aromatic hydrocarbons (PAH's) which can be diagenetically related to the steroid or extended-side-chain hopane skeletons.