SciCombinator

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Concept: Naphthalene

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Concentrations of 22 polycyclic aromatic hydrocarbons (PAHs) were estimated for individual particle-size distributions at the airport apron of the Taipei International Airport, Taiwan, on 48 days in July, September, October, and December of 2011. In total, 672 integrated air samples were collected using a micro-orifice uniform deposition impactor (MOUDI) and a nano-MOUDI. Particle-bound PAHs (P-PAHs) were analyzed by gas chromatography with mass selective detector (GC/MSD). The five most abundant species of P-PAHs on all sampling days were naphthalene (NaP), phenanthrene (PA), fluoranthene (FL), acenaphthene (AcP), and pyrene (Pyr). Total P-PAHs concentrations were 152.21, 184.83, and 188.94 ng/m(3) in summer, autumn, and winter, respectively. On average, the most abundant fractions of benzo[a]pyrene equivalent concentration (BaPeq) in different molecular weights were high-weight PAHs (79.29 %), followed by medium-weight PAHs (11.57 %) and low-weight PAHs (9.14 %). The mean BaPeq concentrations were 1.25 and 0.94 (ng/m(3)) in ultrafine particles (<0.1 μm) and nano-particles (<0.032 μm), respectively. The percentages of total BaPeq in nano- and ultrafine particulate size ranges were 52.4 % and 70.15 %, respectively.

Concepts: Polycyclic aromatic hydrocarbon, Aromaticity, Airport, Naphthalene, Phenanthrene, Polycyclic aromatic hydrocarbons, Pyrene, Fluoranthene

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Cosolubilization of polycyclic aromatic hydrocarbons (PAHs) (naphthalene and pyrene) has been studied in surfactant systems of varying nature of their head-group viz. nonionic: Brij30 and Brij56, cationic: DDEAB and CTAB and anionic: SDS. Solubilization capacity of micelles was quantified in terms of molar solubilization ratio, the micelle-water partition coefficient, the first stepwise association constant and average number of solubilizate molecules per micelle determined by employing spectrophotometric and tensiometric techniques. Solubilization capacity of all the surfactant systems was generally higher for naphthalene than pyrene and followed the order: nonionics>cationics>anionic surfactant. Solubility of naphthalene decreased during cosolubilization in all surfactant systems studied while the solubility of pyrene decreased only in Brij30 and Brij56 surfactant systems due to competitive solubilization of PAHs for the same solubilization site. The solubility of pyrene, however, enhanced in presence of naphthalene in CTAB, DDEAB and SDS surfactant systems owing to increase in core volume of the micelles by the palisade layer solubilization of naphthalene. The results of this study can provide valuable information on the selection of particular surfactant systems for selective separation of naphthalene and pyrene from their mixture relevant to surfactant enhanced remediation (SER) technology at the contaminated sites.

Concepts: Polycyclic aromatic hydrocarbon, Benzene, Hydrocarbon, Surfactant, Micelle, Aromaticity, Naphthalene, Pyrene

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Cooking oil fumes (COF) contain polycyclic aromatic hydrocarbons (PAHs), heterocyclic aromatic amines, benzene, and formaldehyde, which may cause oxidative damages to DNA and lipids. We assessed the relations between exposure to COF and subsequent oxidative DNA damage and lipid peroxidation among military cooks and office-based soldiers. The study population, including 61 Taiwanese male military cooks and a reference group of 37 office soldiers, collected urine samples pre-shift of the first weekday and post-shift of the fifth workday. We measured airborne particulate PAHs in military kitchens and offices and concentrations of urinary 1-OHP, a biomarker of PAH exposure, urinary 8-hydroxydeoxyguanosine (8-OHdG), a biomarkers of oxidative DNA damage, and urinary isoprostane (Isop). Airborne particulate PAHs levels in kitchens significantly exceeded those in office areas. The concentrations of urinary 1-OHP among military cooks increased significantly after 5 days of exposure to COF. Using generalized estimating equation analysis adjusting for confounding, a change in log(8-OHdG) and log(Isop) were statistically significantly related to a unit change in log(1-OHP) (regression coefficient (β), β=0.06, 95% CI 0.001-0.12) and (β=0.07, 95% CI 0.001-0.13), respectively. Exposure to PAHs, or other compounds in cooking oil fumes, may cause both oxidative DNA damage and lipid peroxidation.

Concepts: Regression analysis, Carbon, Polycyclic aromatic hydrocarbon, Benzene, Hydrocarbon, Aromatic hydrocarbon, Aromaticity, Naphthalene

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Potentially toxic 16 priority polycyclic aromatic hydrocarbons (PAHs) were determined in four brands of grounded coffee. Four to 13 PAHs were detected. Concentrations of total PAHs in different brands of coffee samples were in the range of 831.7-1,589.7 μg/kg. Benzo[a]pyrene (2A: probable human carcinogen) was found in Nescafe Premium whereas naphthalene (2B: possible human carcinogen) was found in all the samples of coffee.

Concepts: Carbon, Polycyclic aromatic hydrocarbon, Benzene, Hydrocarbon, Aromatic hydrocarbon, Aromaticity, Naphthalene, Carcinogens

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In this study, flotation-assisted homogeneous liquid-liquid microextraction (FA-HLLME) was developed as a fast, simple, and efficient method for extraction of four polycyclic aromatic hydrocarbons (PAHs) in soil samples followed by gas chromatography-flame ionization detector (GC-FID) analysis. A special home-made extraction cell was designed to facilitate collection of the low-density extraction solvent without a need for centrifugation. In this method, PAHs were extracted from soil samples into methanol and water (1:1, v/v) using ultrasound in two steps followed by filtration as a clean-up step. The filtrate was added into the home-made extraction cell contained mixture of 1.0mL methanol (homogenous solvent) and 150.0μL toluene (extraction solvent). Using N(2) flotation, the dispersed extraction solvent was transferred to the surface of the mixture and was collected by means of a micro-syringe. Then, 2μL of the collected organic solvent was injected into the GC-FID for subsequent analysis. Under optimal conditions, linearity of the method was in the range of 40-1000μgkg(-1) soil (dry weight). The relative standard deviations in real samples varied from 5.9 to 15.2% (n=4). The proposed method was successfully applied to analyze the target PAHs in soil samples, and satisfactory results were obtained.

Concepts: Ethanol, Polycyclic aromatic hydrocarbon, Benzene, Solvent, Aromatic hydrocarbon, Toluene, Naphthalene

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The Tubarão River rises in Santa Catarina, Brazil, and has been historically affected by coal mining activities around its springhead. To evaluate its water conditions, an investigation regarding a possible decontamination gradient associated with the increased river flow toward the estuary, as well as the influence of seasonality over this gradient was performed through a series of biomarkers (vitellogenin, comet assay, lipid peroxidation, protein carbonylation, gluthatione, gluthatione S-transferase, acetylcholinesterase, light microscopy in liver, and scanning electron microscopy in gills) and chemical analysis (polycyclic aromatic hydrocarbons (PAHs) in bile and metal analysis in sediment) in the cichlid Geophagus brasiliensis. Two collections (summer and winter) were made in four distinct sites along the river, while sediments were sampled between those seasons. As expected, the contamination linked exclusively to mining activities was not observed, possibly due to punctual inputs of contaminants. The decontamination gradient was not observed, although seasonality seemed to have a critical role in the responses of biomarkers and availability of contaminants. In the summer, the fish presented higher histopathological damages and lower concentrations of PAHs, while in the winter they showed both higher genetic damage and accumulation of PAHs. The Tubarão suffers impacts from diverse activities, representing health risks for wild and human populations.

Concepts: Electron, Water, Polycyclic aromatic hydrocarbon, River, Estuary, Scanning electron microscope, Aromaticity, Naphthalene

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The use of biomaterials or microorganisms in PAHs degradation had presented an eye-catching performance. Pleurotus eryngii is a white rot fungus, which is easily isolated from the decayed woods in the tropical rain forest, used to determine the capability to utilize naphthalene, a two-ring polycyclic aromatic hydrocarbon as source of carbon and energy. In the meantime, biotransformation of naphthalene to intermediates and other by-products during degradation was investigated in this study. Pleurotus eryngii had been incubated in liquid medium formulated with naphthalene for 14 days. The presence of metabolites of naphthalene suggests that Pleurotus eryngii begin the ring cleavage by dioxygenation on C1 and C4 position to give 1,4-naphthaquinone. 1,4-Naphthaquinone was further degraded to benzoic acid, where the proposed terepthalic acid is absent in the cultured extract. Further degradation of benzoic acid by Pleurotus eryngii shows the existence of catechol as a result of the combination of decarboxylation and hydroxylation process. Unfortunately, phthalic acid was not detected in this study. Several enzymes, including manganese peroxidase, lignin peroxidase, laccase, 1,2-dioxygenase and 2,3-dioxygenase are enzymes responsible for naphthalene degradation. Reduction of naphthalene and the presence of metabolites in liquid medium showed the ability of Pleurotus eryngii to utilize naphthalene as carbon source instead of a limited glucose amount.

Concepts: Metabolism, Enzyme, Carbon, Polycyclic aromatic hydrocarbon, Benzene, Aromaticity, Naphthalene, Ligninase

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The tendency for chlorinated aliphatics and aromatic hydrocarbons to accumulate in environments such as groundwater and sediments poses a serious environmental threat. In this study, the metabolic capacity of hydrocarbon (aromatics and chlorinated aliphatics)-contaminated groundwater in the KwaZulu-Natal province of South Africa has been elucidated for the first time by analysis of pyrosequencing data. The taxonomic data revealed that the metagenomes were dominated by the phylum Proteobacteria (mainly Betaproteobacteria). In addition, Flavobacteriales, Sphingobacteria, Burkholderiales, and Rhodocyclales were the predominant orders present in the individual metagenomes. These orders included microorganisms (Flavobacteria, Dechloromonas aromatica RCB, and Azoarcus) involved in the degradation of aromatic compounds and various other hydrocarbons that were present in the groundwater. Although the metabolic reconstruction of the metagenome represented composite cell networks, the information obtained was sufficient to address questions regarding the metabolic potential of the microbial communities and to correlate the data to the contamination profile of the groundwater. Genes involved in the degradation of benzene and benzoate, heavy metal-resistance mechanisms appeared to provide a survival strategy used by the microbial communities. Analysis of the pyrosequencing-derived data revealed that the metagenomes represent complex microbial communities that have adapted to the geochemical conditions of the groundwater as evidenced by the presence of key enzymes/genes conferring resistance to specific contaminants. Thus, pyrosequencing analysis of the metagenomes provided insights into the microbial activities in hydrocarbon-contaminated habitats.

Concepts: Bacteria, Biotechnology, Benzene, Hydrocarbon, Proteobacteria, Aromatic hydrocarbon, Aromaticity, Naphthalene

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Cancer incidence appears to be higher amongst firefighters compared to the general population. Given that many cancers have an environmental component, their occupational exposure to products of carbon combustion such as polycyclic aromatic hydrocarbons (PAHs) is of concern. This is the first UK study identifying firefighters exposure to PAH carcinogens. Wipe samples were collected from skin (jaw, neck, hands), personal protective equipment of firefighters, and work environment (offices, fire stations and engines) in two UK Fire and Rescue Service Stations. Levels of 16 US Environmental Protection Agency (EPA) PAHs were quantified together with more potent carcinogens: 7,12-dimethylbenzo[a]anthracene, and 3-methylcholanthrene (3-MCA) (12 months post-initial testing). Cancer slope factors, used to estimate cancer risk, indicate a markedly elevated risk. PAH carcinogens including benzo[a]pyrene (B[a]P), 3-MCA, and 7,12-dimethylbenz[a]anthracene PAHs were determined on body surfaces (e.g., hands, throat), on PPE including helmets and clothing, and on work surfaces. The main exposure route would appear to be via skin absorption. These results suggest an urgent need to monitor exposures to firefighters in their occupational setting and conduct long-term follow-up regarding their health status.

Concepts: Polycyclic aromatic hydrocarbon, Benzene, Personal protective equipment, United States Environmental Protection Agency, Protection, Environmentalism, Occupational safety and health, Naphthalene

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Hot dip galvanizing (HDG) processes are sources of polychlorinated-p-dioxins and dibenzofurans (PCDD/Fs). Close correlations have been found between the concentration of PCDD/Fs and polychlorinated naphthalenes (PCNs) that are produced and released during industrial thermal processes. We speculated, therefore, that HDG plants are potential PCN sources. In this preliminary study, PCNs were analyzed in solid residues, ash and precipitate from three HDG plants of different sizes. The total PCN concentrations (∑2-8PCNs) in the residue samples ranged from 60.3 to 226pgg(-1). The PCN emission factors for the combined ash and precipitate residues from the HDG plants ranged from 75 to 178ngt(-1) for the dichlorinated and octachlorinated naphthalenes. The preliminary results suggested that the HDG industry might not currently be a significant source of PCN emissions. The trichloronaphthalenes were the dominant homologs followed by the dichloronaphthalenes and the tetrachloronaphthalenes. The PCN congeners CN37/33/34, CN52/60, CN66/67, and CN73 dominated the tetrachlorinated, pentachlorinated, hexachlorinated, and heptachlorinated naphthalene homologs, respectively. The PCNs emitted from the HDG plants had similar homolog distributions and congener profiles to the PCNs emitted from combustion plants and other metallurgical processes. The identification and preliminary evaluation of PCN emissions from HDG plants presented here will help in the prioritization of measures for controlling PCN emissions from industrial sources.

Concepts: Concentration, Domination, Metallurgy, Naphthalene, Congener, Hot-dip galvanizing, AP 42 Compilation of Air Pollutant Emission Factors