Polycyclic Aromatic Hydrocarbons In Samples Research Articles

Passive sampling of polycyclic aromatic hydrocarbons with low-density polyethylene: Equilibration limitations in aqueous suspensions

Polyethylene (PE) and other polymers are widely and successfully used as passive samplers for organic pollutants in the environment. This study provides high-resolution experimental data from batch shaking tests on the uptake, reversibility, and linear equilibrium partitioning of polycyclic aromatic hydrocarbons (PAHs) using two different PE sheets of 30 µm and 80 µm thickness. Kinetics for phenanthrene are well described by a mechanistic first-order model with mass transfer limited by an aqueous boundary layer (with a mean thickness of 170 µm). Equilibration in laboratory batch systems during uptake and desorption is very rapid with characteristic times of 1–2 h but this depends on the boundary condition, e.g., the ratio of PE mass to water volume. Therefore, equilibration of PE in other setups, e.g., in soil slurries or sediment suspensions, may take orders of magnitude longer because the boundary condition for PE changes from finite to infinite bath conditions (soil or sediment particles may keep the concentration in water almost constant). Solid precipitates for high molecular weight PAHs explain partition coefficients below expected values because of kinetic limitations in such a system. Nevertheless, passive sampling can be employed safely if such limitations are considered; furthermore, partition coefficients can be estimated accurately by empirical relationships (e.g., within 0.1 log unit) based on molecular weight, octanol/water partition coefficients, or subcooled liquid solubilities.

Evaluation of exposure to volatile organic compounds (BTEX) and Polycyclic Aromatic Hydrocarbons (PAHs) in gas station workers and oxidative stress assessment in Karaj city

Gas stations are one of the sources of benzene, toluene, ethylbenzene and xylene (BTEX) and polyromantic hydrocarbons (PAHs). The present study was conducted with the aim of evaluating the level of breathing exposure of gas station workers to BTEX, PAHs and oxidative stress caused by exposure to these compounds in Karaj city. Oxidative stress and reactive oxygen species (ROS) is one of the mechanisms involved in the toxicity caused by exposure to gas vapors. In this study, all 25 gas stations in the city of Karaj were investigated. Personal sampling and analysis of BTEX and PAHs was done according to National Institute for Occupational Safety and Health (NIOSH) 1501 and 5515 methods, respectively. Finally, oxidative stress markers were investigated in 25 gas station workers and 25 control group. The results showed that the mean age and employment history of gas station workers are 39.96 ± 9.55 and 12.84 ± 6.92, respectively. Also, no significant difference was reported between gas station workers and control subjects in terms of oxidative stress parameters including the level of ROS, oxidized glutathione (GSSG) content, malondialdehyde (MDA) and reduced glutathione (GSH) content. The concentration values of personal exposure of gas station workers to BTEX and PAHs are lower than the occupational exposure limits (OEL). Although the level of oxidative stress parameters in gas station workers is higher than the control group, this difference is not statistically significant (p>0.05). It is recommended to take personal protection measures in case of chronic exposure.

Polycyclic aromatic hydrocarbons (PAHs) in black crusts on stone monuments in Milan: detection, quantification, distributions, and source assessment

In the field of conservation of cultural heritage, one must always consider the environmental conditions in which the works of art are located and the level of atmospheric pollution to which they are exposed, especially in the case of monuments stored outdoors. The present study is focused on the detection and the quantification of polycyclic aromatic hydrocarbons (PAHs) in black crust samples from the Monumental Cemetery of Milan (Italy), and the assessment of their sources through the analysis of the distributions of the different compounds in the samples, together with the use of diagnostic ratios. Six black crust samples taken from funerary monuments were analyzed. Fourteen polycyclic aromatic hydrocarbons were identified (naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene) by high-performance liquid chromatography with a diode-array detector (HPLC–DAD), with a total concentration from 0.72 to 3.81 μg/g (mean of 1.87 μg/g). The known carcinogenic benzo[a]pyrene accounted for 5–10% of the total polycyclic aromatic hydrocarbons in the samples analyzed, with concentrations up to 0.20 μg/g. Moreover, the study of the distribution and diagnostic ratios allowed us to confirm that anthropogenic sources such as traffic and the proximity of the train station are the major causes of the degradation of the monuments contained in this Cemetery.

Needle trap devices packed with an imine-based 2D COF: An innovative tool for the sampling of polycyclic aromatic hydrocarbons in air

This study introduces a new method for sampling and microextraction of polycyclic aromatic hydrocarbons (PAHs) in the air using needle trap devices (NTDs) packed with an imine-based covalent-organic framework (COF) as an adsorbent. The NTD was coupled with gas chromatography-flame ionization detection (GC-FID) for analytes’ separation and quantification. The COF adsorbent was synthesized using a solvothermal method at room temperature and packed inside a stainless-steel needle. The adsorbent was characterized using X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM-EDS) and Brunauer-Emmett-Teller (BET) analysis. The method was developed in the laboratory under various conditions and subsequently applied in the field to compare the results with those obtained using sampling and analytical method-NIOSH 5528. The desorption conditions and breakthrough volume (BtV) were optimized at recommended exposure limits concentration using response surface methodology (RSM) with a central composite design (CCD). Accordingly, the optimal values for desorption temperature and BtV were obtained 310 °C and 2840 mL, respectively. The limits of detection (LODs) and the limits of quantification (LOQs) were found to be 0.021–0.027 and 0.065–0.091 μg L−1, respectively. The repeatability and reproducibility of the method (R%) were estimated to be 4.02–6.83 % and 8.51–10.34 %, respectively. Also comparing the mean concentrations of the samples collected by the NTD and the NIOSH 5528 method, revealed no statistically significant differences between the methods (p > 0.05). Overall, the COF-packed NTD was identified as an appropriate and reliable method for sampling and extracting occupational and ambient contaminants in the workplace air.

Polycyclic aromatic hydrocarbons in samples of Ryugu formed in the interstellar medium.

Polycyclic aromatic hydrocarbons (PAHs) contain ≲20% of the carbon in the interstellar medium. They are potentially produced in circumstellar environments (at temperatures ≳1000 kelvin), by (~10 kelvin) interstellar clouds, or by processing of carbon-rich dust grains. We report isotopic properties of PAHs extracted from samples of the asteroid Ryugu and the meteorite Murchison. The doubly-13C substituted compositions (Δ2×13C values) of the PAHs naphthalene, fluoranthene, and pyrene are 9 to 51‰ higher than values expected for a stochastic distribution of isotopes. The Δ2×13C values are higher than expected if the PAHs formed in a circumstellar environment, but consistent with formation in the interstellar medium. By contrast, the PAHs phenanthrene and anthracene in Ryugu samples have Δ2×13C values consistent with formation by higher-temperature reactions.

A novel needle trap device containing an imine-based covalent organic framework for sampling of PAHs in soil

A new adsorbent based on covalent organic frameworks (COFs) was synthesized through imine condensation and utilized for the needle trap device (NTD) microextraction. The structure and surface properties of the synthesized adsorbent were investigated using Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), Brunauer-Emmett-Teller (BET) surface area analysis, and X-ray diffraction analysis (XRD), techniques. The designed microextraction system was coupled with a gas chromatography flame ionization detector (GC-FID) and used for the measurement of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil samples. The statistical response surface methodology (RSM) with a Box-Behnken design (BBD) was used to investigate and optimize the effective variables in the extraction process, including extraction temperature, extraction time, and sample flow rate. Under optimal conditions, the calibration curves were linear over the range of 0.2–10000 ng g−1. The detection limit of the method for the PAHs was obtained in the range of 0.01–0.05 ng g−1. The RSD values were obtained 7.6–12.9%. The NTD-GC-FID procedure based on COF adsorbent was successfully utilized for the analysis of PAHs in contaminated soil samples.

Measurement of Polycyclic Aromatic Hydrocarbons (PAHs) on Indoor Materials: Method Development.

Wildfire smoke penetrates indoors, and polycyclic aromatic hydrocarbons (PAHs) in smoke may accumulate on indoor materials. We developed two approaches for measuring PAHs on common indoor materials: (1) solvent-soaked wiping of solid materials (glass and drywall) and (2) direct extraction of porous/fleecy materials (mechanical air filter media and cotton sheets). Samples are extracted by sonication in dichloromethane and analyzed with gas chromatography-mass spectrometry. Extraction recoveries range from 50-83% for surrogate standards and for PAHs recovered from direct application to isopropanol-soaked wipes, in line with prior studies. We evaluate our methods with a total recovery metric, defined as the sampling and extraction recovery of PAHs from a test material spiked with known PAH mass. Total recovery is higher for "heavy" PAHs (HPAHs, 4 or more aromatic rings) than for "light" PAHs (LPAHs, 2-3 aromatic rings). For glass, the total recovery range is 44-77% for HPAHs and 0-30% for LPAHs. Total recoveries from painted drywall are <20% for all PAHs tested. For filter media and cotton, total recoveries of HPAHs are 37-67 and 19-57%, respectively. These data show acceptable HPAH total recovery on glass, cotton, and filter media; total recovery of LPAHs may be unacceptably low for indoor materials using methods developed here. Our data also indicate that extraction recovery of surrogate standards may overestimate the total recovery of PAHs from glass using solvent wipe sampling. The developed method enables future studies of accumulation of PAHs indoors, including potential longer-term exposure derived from contaminated indoor surfaces.

Comparison of generic Tenax and specialized PAH tubes for monitoring polycyclic aromatic hydrocarbons in the ambient air

The thermal desorption (TD) technique has potential advantages for monitoring polycyclic aromatic hydrocarbons (PAHs) in the air, e.g., no need for sample preparation. This study aims to compare the performance of two types of TD tubes: the generic Tenax TA tube and a proprietary PAH tube specifically designed for PAH sampling. Full calibrations were performed on a TD-gas chromatography/mass spectrometry (GC/MS) system for 16 priority PAHs. Co-located field samples were collected with two tubes at a flow rate of 200 mL/min for 24 h in eight rounds. In the laboratory, blank Tenax and PAH tubes had trace-level PAHs ranging from 0 to 0.35 ng/tube and 0−0.83 ng/tube, respectively, after 2-hr conditioning at 330 °C. The calibration with Tenax tubes showed an average precision of 7.5%, R2 from 0.9959 to 1.0000, and method detection limits (MDLs) from 0.056 to 3.64 ng/m3. The calibration of PAH tubes showed an average precision of 7.5%, R2 from 0.9945 to 1.0000, and MDLs from 0.065 to 5.91 ng/m3. In the field, blank Tenax and PAH tubes had trace PAH levels of 0.01–0.34 ng/tube and 0.01−0.42 ng/tube, respectively. Both tubes had negligible breakthroughs (<4%) and good precisions (<20%). Co-located Tenax and PAH tubes displayed a good agreement for light PAHs (differences mostly <30%) but high uncertainty for heavy PAHs (difference 35−70%). Both tubes are applicable for PAH monitoring, but the proprietary PAH tube does not outperform the generic Tenax TA tube. More work is still needed to improve the sensitivity of TD methods for heavy PAHs, e.g., selecting appropriate sorbents and adopting advanced instruments.

Effect of n-Butanol Addition to Diesel Fuel on Reduction of PAH Formation and Regulated Pollutants

The primary motivation of this paper is to report the effects of n-butanol addition (5, 20 and 35% by volume) to diesel fuel on regulated and polycyclic aromatic hydrocarbon (PAH) emissions of a diesel engine. PAH samples were quantified using rigorous analytical chemistry procedures to determine total PAHs, PAH dispersion and PAH toxicity. In comparison with diesel fuel, all n-butanol blends (DBu5, DBu20, and DBu35) reduced nitrogen oxides (NOx) emissions by 6.77%, 9.59%, and 20.08% and total PAH emissions by 66.86%, 75.33%, and 80.98%. In terms of the relative distribution of PAHs, a significant decrease was recorded in higher cyclic PAHs such as Pyrene, Benzo[a]anthracene, Chrysene, Benzo[k]floranthene, Benzo[a]pyrene for all blends. Similarly, the amount of the toxicity of the PAH emissions also decreased by 11.66%, 87.53%, and 67.28% with DBu5, DBu20 and DBu35 blends, respectively. With the addition of n-butanol to the diesel fuel, total PAH emissions were detected below the Occupational Safety and Health Administration’s (OSHA)-Permissible Exposure Level. Overall, it was demonstrated that n-butanol addition to diesel fuel significantly reduced PAH formation which is helpful to prevent wet stacking, and prolong the operating time of the diesel engine especially at low loads or cold operating conditions.

Quantitative analysis of polycyclic aromatic hydrocarbons (PAHs) in water by surface-enhanced Raman spectroscopy (SERS) combined with Random Forest

Polycyclic aromatic hydrocarbons (PAHs) have strong carcinogenicity, teratogenicity, mutagenicity and other adverse effects on human beings. They are one of the most dangerous pollutants, which have attracted great attention in the past decades. In this work, aiming at the actual problems that water environment is polluted and human health is threatened by PAHs, surface enhanced Raman spectroscopy (SERS) combined with Random Forest (RF) calibration models were used to quantitative analysis of phenanthrene and fluoranthene in water. Firstly, the SERS data was collected after samples mixed with Ag NPs, after 31 PAHs samples were prepared. Secondly, it was discussed how spectral preprocessing integration strategies affect on the prediction performance of the RF calibration models. And then, the effect of mutual information (MI) variable selection method on the performance of RF calibration models was explored. Finally, the RF calibration models were established for phenanthrene and fluoranthene. For the prediction set, a lowest mean relative error (MRE) and a largest determination coefficient (R2) were obtained. For quantitative analysis of phenanthrene, the final prediction performance results show that R2p is 0.9780, and MREp is 0.0369 based on the D1st-WT-RF calibration model. For fluoranthene, WT-D1st-MI-RF is a better calibration model, and corresponding to R2p and MREp are 0.9770 and 0.0694, respectively. Hence, a rapid and accurate quantitative method of PAHs is established for the real-time detection of water environmental pollution, which is intended to provide new ideas and methods for the quantitative analysis of PAHs in water.

Fuel effects on PAH formation, toxicity and regulated pollutants: Detailed comparison of biodiesel blends with propanol, butanol and pentanol

Blends of biodiesel and high-carbon alcohols have the potential to increase the rate of biofuel use in diesel engines, while reducing harmful and toxic compounds such as polycyclic aromatic hydrocarbons (PAHs). Since biodiesel and alcohols do not contain aromatic ingredients in their chemical structures, this study examined biodiesel blends with propanol, n-butanol, and 1-pentanol (5 %, 20 % and 35 % by vol.) and the effects of these aromatic-free fuels on regulated emissions, PAH formation and toxicity as compared to straight diesel fuel in a diesel engine operating at a constant speed and varying engine loads. PAH samples were meticulously processed and extensively analyzed using rigorous analytical chemistry methodology (gas chromatography–mass spectrometry (GC–MS)). Biodiesel and biodiesel-alcohol blends significantly reduced NOx emissions and the level of formation of PAHs and toxicity levels when compared to diesel fuel. Overall, adding 5 % alcohol to biodiesel decreased total PAH emissions. However, with the exception of 20 % propanol, adding 20 % and 35 % alcohol to biodiesel increased total PAH emissions as compared to neat biodiesel. In contrast, all blended fuels resulted in a decrease in the toxicity of PAH compounds (up to 70 %) and the percentage of higher-ring PAHs. Among higher alcohols, propanol blends stood out as reducing PAH formation as compared to n-butanol and pentanol blends. Overall, biodiesel-alcohol blends that emit less carcinogenic pollutants and primarily low-rings PAHs were found to be advantageous for reducing the likelihood of wetstacking in diesel engines under low load or cold operating conditions.

Formation of polycyclic aromatic hydrocarbons and regulated emissions from biodiesel and n-butanol blends containing water

To increase the use of biofuels in diesel engines and reduce harmful emissions emitted from diesel fuel, biodiesel and higher alcohols are fuel sources at the forefront of research. The aim of this study is to understand the effect of water-containing n-butanol-biodiesel blends on regulated emissions, emphasizing nitrogen oxides (NOx) and polycyclic aromatic hydrocarbons (PAHs), which are harmful for the environment and engine durability. 10% n-butanol (B90Bu10) and 10% n-butanol-1% water (B89Bu10W1) were blended with 89% waste-oil biodiesel and tested in a diesel engine at four engine loads at a constant engine speed. PAH samples were analyzed using gas chromatography-mass spectrometry (GC-MS). Results showed B100, B90Bu10 and B89Bu10W1 blends increased break specific fuel consumption (BSFC), exhaust gas temperatures (EGT), carbon monoxide (CO) and hydrocarbon (HC) emissions. However, NOx emissions significantly decreased using butanol and butanol-water blends. Compared to diesel, biodiesel and blended fuels significantly reduced total PAHs and PAH toxicity up to 75.0%. However, B89Bu10W1 increased total PAH and PAH toxicity by 35.7%. Overall, the biodiesel-butanol blend, which emits less carcinogenic pollutants and low-cyclic PAHs than water-containing fuel, was found to reduce the risk of wetstacking in diesel engines operating under low loads.

Simultaneous Determination of Multi-Class Pesticide Residues and PAHs in Plant Material and Soil Samples Using the Optimized QuEChERS Method and Tandem Mass Spectrometry Analysis.

New analytical approaches to the simultaneous identification and quantification of 94 pesticides and 13 polycyclic aromatic hydrocarbons (PAHs) in five representative matrices (pepper, apple, lettuce, wheat, and soil) were developed. The analyses were based on gas chromatography coupled with triple quadrupole tandem mass spectrometry (GC-MS/MS). The procedure was optimized by changing the solvent used during the extraction, from acetonitrile to the acetone: n-hexane mixture at a volume ratio of 1:4 (v/v), as well as the use of a reduced amount of water during the extraction of compounds from cereals. An additional modification was the use of florisil instead of GCB in the sample cleanup step. A full method validation study was performed, at two concentration levels (LOQ and 1000 × LOQ), which showed satisfactory results for all analytes from the PAHs group, with recoveries ranging from 70.7–115.1%, and an average RSD of 3.9%. Linearity was tested in the range of 0.001–1.000 mg/kg and showed coefficients of determination (R2) ≥ 0.99 for all PAHs. Satisfactory recovery and precision parameters (LOQ and 100 × LOQ) were achieved for almost all analytes from the pesticide group in the range of 70.1–119.3% with the mean RSD equal to 5.9%. The observed linearity for all analytes in the concentration range of 0.005–1.44 mg/kg was R2 ≥ 0.99, with the exception of famoxadone, chizalofop-p-ethyl, prothioconazole, spirodiclofen, tefluthrin, and zoxamid. The extended uncertainties were estimated, using a top-down approach of 9.9% (average) and 15.3% (average) for PAHs and pesticides samples, respectively (the coverage factor k = 2, the 95% confidence level). Ultimately, the method was successfully applied to determine pesticide residues in commercial samples of fruit, vegetables and grain, and soil samples for PAHs, which were collected from selected places in the Podkarpacie region. A total of 38 real samples were tested, in which 10 pesticides and 13 PAHs were determined. Proposed changes allow us to shorten the sample preparation time (by 20%) and to reduce the consumption of organic solvents (by 17%). The use of florisil for sample cleanup, instead of GCB, improves the recovery of compounds with flat particles.

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.

The Influence of Environmental Polycyclic Aromatic Hydrocarbons (PAHs) Exposure on DNA Damage among School Children in Urban Traffic Area, Malaysia.

This study aimed to investigate the association between particulate PAHs exposure and DNA damage in Malaysian schoolchildren in heavy traffic (HT) and low traffic (LT) areas. PAH samples at eight schools were collected using a low volume sampler for 24 h and quantified using Gas Chromatography-Mass Spectrometry. Two hundred and twenty-eight buccal cells of children were assessed for DNA damage using Comet Assay. Monte-Carlo simulation was performed to determine incremental lifetime cancer risk (ILCR) and to check the uncertainty and sensitivity of the estimated risk. Total PAH concentrations in the schools in HT area were higher than LT area ranging from 4.4 to 5.76 ng m−3 and 1.36 to 3.79 ng m−3, respectively. The source diagnostic ratio showed that PAHs in the HT area is pyrogenic, mainly from diesel emission. The 95th percentile of the ILCR for children in HT and LT area were 2.80 × 10−7 and 1.43 × 10−7, respectively. The degree of DNA damage was significantly more severe in children in the HT group compared to LT group. This study shows that total indoor PAH exposure was the most significant factor that influenced the DNA damage among children. Further investigation of the relationship between PAH exposure and genomic integrity in children is required to shed additional light on potential health risks.

Photochemical Synthesis and Spectroscopy of Covalent PAH Dimers.

Laser photochemistry of pressed-pellet samples of polycyclic aromatic hydrocarbons (PAHs) produces covalently bonded dimers and some higher polymers. This chemistry was discovered initially via laser desorption time-of-flight mass spectrometry experiments, which produced masses (m/z) of 2M-2 and 2M-4 (where M is the monomer parent mass). Dimers are believed to be formed from photochemical dehydrogenation and radical polymerization chemistry in the desorption plume. Replication of these ablation conditions at higher throughput allowed PAH dimers of pyrene, perylene, and coronene to be produced and collected in milligram quantities. Differential sublimation provided purification of the dimers and elimination of residual monomers. The purified dimers were investigated with UV-visible, IR, and Raman spectroscopy, complemented by computational studies using density functional theory at the CAM-B3LYP/def2-TZV level. Calculations and predicted spectra were calibrated by comparison with the corresponding monomers and used to determine the lowest energy dimer structures. Infrared and Raman spectroscopy provided few distinctive signatures, but UV-visible spectra detected new transitions for each dimer. The comparison of simulated and experimental spectra allows determination of the most prevalent structures for the PAH dimers. The work presented here provides interesting insights into the spectroscopy of extended aromatic systems and a new strategy for the photochemical synthesis of large PAH dimers.

Isolation, identification, and degradation characteristics of three effective PAHs degradation strains

Isolating dominant strains for the degradation of polycyclic aromatic hydrocarbons (PAHs) is of great practical significance for the restoration of ecosystem polluted by PAHs. A total of 11 strains with capacity of degrading PAHs were obtained from soil polluted by PAHs around a coking plant, by enrichment culture, acclimation, and plate isolation. Three of them with effective PAH-degrading capability were identified and screened out by morphological observation, physiobiochemical characterization, and 16S rRNA gene sequencing, and respectively, named as DJ-3, DJ-8 and DJ-10. Based on the results of 16S rRNA gene sequencing, DJ-3, DJ-8, and DJ-10 were identified as Pseudomonas sp. Klebsiella sp., and Bacillus sp. The degradation rate of phenanthrene (200 mg·L-1), pyrene (200 mg·L-1), and naphthol (160 mg·L-1) by three strains (DJ-3, DJ-8 and DJ-10) after seven-day incubation were 48.9%-65.9%, 38.9%-43.1%, and 57.6%-64.9%, respectively. The degradation rates of mixed PAHs sample (1200 mg·L-1) by three strains were 49.1%, 44.5%, and 53.9%, which were significantly higher than other eight strains, indicating that they were highly effective in PAHs degradation. There was no antagonistic relationship among the three strains. This study would lay a foundation for building efficient PAHs degrading strains and improve the in situ bioremediation of PAHs contaminated soil.

Anthracene and Pyrene Biodegradation Performance of Marine Sponge Symbiont Bacteria Consortium.

Every petroleum-processing plant produces sewage sludge containing several types of polycyclic aromatic hydrocarbons (PAHs). The degradation of PAHs via physical, biological, and chemical methods is not yet efficient. Among biological methods, the use of marine sponge symbiont bacteria is considered an alternative and promising approach in the degradation of and reduction in PAHs. This study aimed to explore the potential performance of a consortium of sponge symbiont bacteria in degrading anthracene and pyrene. Three bacterial species (Bacillus pumilus strain GLB197, Pseudomonas stutzeri strain SLG510A3-8, and Acinetobacter calcoaceticus strain SLCDA 976) were mixed to form the consortium. The interaction between the bacterial consortium suspension and PAH components was measured at 5 day intervals for 25 days. The biodegradation performance of bacteria on PAH samples was determined on the basis of five biodegradation parameters. The analysis results showed a decrease in the concentration of anthracene (21.89%) and pyrene (7.71%), equivalent to a ratio of 3:1, followed by a decrease in the abundance of anthracene (60.30%) and pyrene (27.52%), equivalent to a ratio of 2:1. The level of pyrene degradation was lower than that of the anthracene due to fact that pyrene is more toxic and has a more stable molecular structure, which hinders its metabolism by bacterial cells. The products from the biodegradation of the two PAHs are alcohols, aldehydes, carboxylic acids, and a small proportion of aromatic hydrocarbon components.

Validation of an analytical technique, distribution, and risk assessment of aliphatic and polycyclic aromatic hydrocarbons in surface sediments of the coastal and selected estuaries of Sarawak

This study explains a validation of an analytical technique, monitoring, and risk evaluation of hydrocarbons in surface sediments of the coastal and selected estuaries of Sarawak, Malaysia. The performance of an analytical methodology was validated for the evaluation of hydrocarbons in coastal and estuaries sediment samples. After the clean-up and separation process, GC-FID and GC-MS were used to quantify aliphatic and polycyclic aromatic hydrocarbon extracts, respectively. The suggested methodology is able to measure aliphatic and polycyclic aromatic hydrocarbons in samples at lower concentrations for example 10 ng/g. The precision of the technique was satisfactory as compared to 15% for most of the analytes. This method gives information concerning the distribution and characteristics of hydrocarbon contaminants in the coastal environment. In regard to monitoring and risk assessment, total n-alkane concentrations (C10–C33) varied from 96.63 to 367.28 ng/g dw. The lowest and highest n-alkane content is observed at Santubong estuary (CZ10) and the coastal site CZ2, respectively. Simultaneously, the contents of ∑PAHs varied from 12.54 to 21.20 ng/g dw. The highest ∑PAH content is reported in the sediments of coastal site CZ8 (21.20 ng/g dw), whereas the lowest content is recorded in the sediments of coastal site CZ3 (12.54 ng/g dw). The outcome of the risk assessment suggested that there is no risk in all the studied locations. The findings from this study will help to understand the sources and possible risks of hydrocarbons in the coastal and estuary settings, and provide information for safeguarding human health and aquatic bodies in the studied area.

Concentrations of polycyclic aromatic hydrocarbons in samples of soil, feed and food collected in the Niger Delta region, Nigeria: A probabilistic human health risk assessment

Polycyclic aromatic hydrocarbons (PAHs) are widely distributed compounds with two or more fused aromatic ring, being some of them classified as carcinogenic. In the present study, the concentrations of 16 PAHs and the sum of them (∑PAHs) were determined in samples of food, feed, plant and soil collected in six different heavily polluted areas (Choba, Khana, Trans Amadi, Eleme, Uyo and Yenagoa) of the Niger Delta Region (Nigeria). Principal component analysis (PCA) was then used to identify groups of variables (PAHs) and groups of samples that were the best in rendering the environmental pollution in that Region of Nigeria. In addition, PAHs food consumption and the derived carcinogenic risks were assessed in a probabilistic way. The highest ∑PAHs (mg/kg) were: 16.7 in cow meat, 8.06 in goat meat, 25.4 in chicken meat, 7.72 in fish, 28.70 in fish feed, 15.3 in chicken feed, 8.42 in plant, and 8.80 in soil. In most of the Nigerian areas, cooked cow meat, chicken and chicken feed presented the highest impact regarding PAHs contamination. The highest intake of PAHs was through meat consumption, with a very high and unassumable carcinogenic risk, which is quite above 10−5 for some PAHs, including benzo [a]pyrene. The results of the present survey highlight the importance of reducing PAHs content in food, specially in meat, in the Niger Delta region.