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1

PAH diagnostic ratios for the identification of pollution emission sources.  

PubMed

Polycyclic aromatic hydrocarbon (PAH) diagnostic ratios have recently come into common use as a tool for identifying and assessing pollution emission sources. Some diagnostic ratios are based on parent PAHs, others on the proportions of alkyl-substituted to non-substituted molecules. The ratios are applicable to PAHs determined in different environmental media: air (gas + particle phase), water, sediment, soil, as well as biomonitor organisms such as leaves or coniferous needles, and mussels. These ratios distinguish PAH pollution originating from petroleum products, petroleum combustion and biomass or coal burning. The compounds involved in each ratio have the same molar mass, so it is assumed they have similar physicochemical properties. Numerous studies show that diagnostic ratios change in value to different extents during phase transfers and environmental degradation. The paper reviews applications of diagnostic ratios, comments on their use and specifies their limitations. PMID:22243855

Tobiszewski, Marek; Namie?nik, Jacek

2012-03-01

2

Source apportionment of polycyclic aromatic hydrocarbons (PAHs) in surface sediments of the Rizhao coastal area (China) using diagnostic ratios and factor analysis with nonnegative constraints.  

PubMed

In this study, sources of polycyclic aromatic hydrocarbons (PAHs) found in surface sediments of the Rizhao coastal area (China) were apportioned using diagnostic ratios and factor analysis with nonnegative constraints (FA-NNC). Bivariate plots of selected diagnostic ratios showed that the sources of PAHs identified in surface sediments seemed to be mixed sources dominated by petroleum-related. Literature PAH source profiles were modified based on the first-order degradation reaction in the atmosphere and sediments, and were considered as comparison for source identification. Five significant factors were determined with the diagnostic tools including coefficient of determination, cumulative percent variance and Exner function. By visually comparing PAH patterns and from the sum of squares of differences between modeled and modified literature PAH profiles, the potential sources were apportioned with the FA-NNC. The main contribution sources of PAHs originated from diesel engine (27.22%), followed by traffic emission (25.03%), gasoline engine (18.95%), coal power plant (14.77%) and coal residential (14.03%). Energy consumption was the predominant reason for PAH pollution in that region. PMID:22115615

Chen, Hai-yang; Teng, Yan-guo; Wang, Jin-sheng

2012-01-01

3

Century-long source apportionment of PAHs in Athabasca oil sands region lakes using diagnostic ratios and compound-specific carbon isotope signatures.  

PubMed

Evaluating the impact that airborne contamination associated with Athabasca oil sands (AOS) mining operations has on the surrounding boreal forest ecosystem requires a rigorous approach to source discrimination. This study presents a century-long historical record of source apportionment of polycyclic aromatic hydrocarbons (PAHs) in dated sediments from two headwater lakes located approximately 40 and 55 km east from the main area of open pit mining activities. Concentrations of the 16 Environmental Protection Agency (EPA) priority PAHs in addition to retene, dibenzothiophene (DBT), and six alkylated groups were measured, and both PAH molecular diagnostic ratios and carbon isotopic signatures (?(13)C) of individual PAHs were used to differentiate natural from anthropogenic inputs. Although concentrations of PAHs in these lakes were low and below the Canadian Council of Ministers of the Environment (CCME) guidelines, diagnostic ratios pointed to an increasingly larger input of petroleum-derived (i.e., petrogenic) PAHs over the past 30 years concomitant with ?(13)C values progressively shifting to the value of unprocessed AOS bitumen. This petrogenic source is attributed to the deposition of bitumen in dust particles associated with wind erosion from open pit mines. PMID:23668471

Jautzy, Josué; Ahad, Jason M E; Gobeil, Charles; Savard, Martine M

2013-06-18

4

PAHs in the Fraser River basin: a critical appraisal of PAH ratios as indicators of PAH source and composition  

Microsoft Academic Search

Parent and alkyl PAHs (51 compounds and alkyl homologues) have been quantified in suspended particulates and sediments (345 samples) from the Fraser River system, British Columbia, Canada. The best potential to distinguish natural and anthropogenic sources is exhibited by ratios of the principal mass 178, 202, 228 and 276 parent PAHs, 1,7\\/2,6+1,7-DMP (dimethylphenanthrene), the phenanthrene\\/anthracene and fluoranthene\\/pyrene alkyl PAH series

Mark B Yunker; Robie W Macdonald; Roxanne Vingarzan; Reginald H Mitchell; Darcy Goyette; Stephanie Sylvestre

2002-01-01

5

Biomonitoring of PAHs by using Quercus ilex leaves: Source diagnostic and toxicity assessment  

NASA Astrophysics Data System (ADS)

Quercus ilex L. leaves were sampled at nineteen urban sites and two remote sites in order to evaluate PAH contamination degree. One-, two- and three-year-old leaves were collected and leaf lipid content was measured to investigate the influence of leaf age and lipids in PAH accumulation. Some PAH diagnostic ratios, such as Ant/Ant + Phen, Flt/Flt + Pyr, B[a]A/B[a]A + Crys and IP/IP + B[g,h,i]P, were calculated. The results suggest that Q. ilex leaves are effective biomonitors of PAH air contamination: in fact, a great PAH accumulation in leaves from the urban areas, until 30-time higher compared to those from the remote sites, has been observed. At each site, the similar total PAH concentrations in leaves of different age, probably due to a canopy effect, indicate an ability of all leaf age classes to monitor local PAH concentrations in air, remarking practical implications for air biomonitoring. The findings suggest that PAH adsorption in Q. ilex leaves does not result limited by leaf lipid content. Moreover, this study demonstrates the source-diagnostic potential of Q. ilex leaves, because, in particular, the Flt/Flt + Pyr and IP/IP + B[g,h,i]P ratios indicate vehicular traffic as the main source of PAHs in the urban areas and wood combustion in the remote areas. Moreover, to distinguish biomass combustion source, a promising tracer PAH as DB[a,h]A could be used. The high contribution of DB[a,h]A to total PAH concentrations at the remote sites determines a high carcinogenic potential in this area, similar to that calculated for the urban area where the carcinogenic PAH concentrations in absolute values are often higher.

De Nicola, Flavia; Claudia, Lancellotti; MariaVittoria, Prati; Giulia, Maisto; Anna, Alfani

2011-03-01

6

Polycyclic Aromatic Hydrocarbons in the Coastal Sediments of Southwestern Taiwan: an Appraisal of Diagnostic Ratios in Source Recognition  

NASA Astrophysics Data System (ADS)

Fifty seven surface sediment samples along the coast of southwestern Taiwan were collected and analyzed for polycyclic aromatic hydrocarbons (PAHs). Concentrations of total PAH (sum of 28 PAH compounds) ranged from15 to 907 ng/g dry weight (dw). Diagnostic ratios revealed petroleum origin PAHs was a significant source to the sediments at Gao-ping estuary stations. However, sediments of Kaohsiung coast might be a combustion-derived PAHs of petroleum, coal, and vehicles. The result of perylene/penta-aromatic PAHs ratio was higher in Tainan coast, Hsinda harbour coast, and some off-shore stations of Kaohsiung coast, suggesting a diagenetic PAH source. A comprehensive appraisal suggested that certain diagnostic ratios are much useful in tracing the distribution of PAHs from specific sources in southwestern Taiwan. P/A (phenanthrene/anthracene) ratio is a better indicator than MP/P (methylphenanthrenes/phenanthrene) ratio in tracing petrogenic PAHs. Moreover, BaA/Chr (benzo(a)anthracene/chrysene) and IP/BghiP (indeno(1,2,3- c,d)pyrene/benzo(g,h,i)perylene) ratios can provide more appropriate assignments than BaP/BeP (benzo(a)pyrene/benzo(e)pyrene) and BbF/BkF (benzo(b)fluoranthcene/benzo(k)fluoranthcene) in distinguishing PAHs from various pyrogenic sources in this study. More specifically, automobile and coal sources were found dominant in stations of pyrogenic group delineated by principal component analysis (PCA).

Jiang, J.; Lee, C.; Fang, M.; Liu, J.

2008-12-01

7

Optimal sampling ratios in comparative diagnostic trials  

PubMed Central

Summary A subjective sampling ratio between the case and the control groups is not always an efficient choice to maximize the power or to minimize the total required sample size in comparative diagnostic trials.We derive explicit expressions for an optimal sampling ratio based on a common variance structure shared by several existing summary statistics of the receiver operating characteristic curve. We propose a two-stage procedure to estimate adaptively the optimal ratio without pilot data. We investigate the properties of the proposed method through theoretical proofs, extensive simulation studies and a real example in cancer diagnostic studies.

Dong, Ting; Tang, Liansheng Larry; Rosenberger, William F.

2014-01-01

8

Diagnostic tests using gene expression ratios  

US Patent & Trademark Office Database

The invention provides methods for diagnosing biological states or conditions based on ratios of gene expression data from cell or tissue samples, such as cancer cell or tissue samples. The invention also provides sets of genes that are expressed differentially in normal and cancer lung cells and tissues. These sets of genes can be used to discriminate between normal and malignant cells or tissues, and between classes of malignant cells or tissues. Accordingly, diagnostic assays for classification of tumors, prediction of tumor outcome, selecting and monitoring treatment regimens and monitoring tumor progression/regression also are provided.

2013-05-28

9

[Compositions and diagnostic ratios of heavily degraded crude oil residues in contaminated soil in oilfields].  

PubMed

The aims of this study were to determine the rate of degradation of crude oil in soil, to reveal the fingerprints of residual oil after long-term biodegradation, and to screen parameters for evaluation of the biodegradability residual oil. A total of 18 contaminated soil samples containing heavily degraded crude oil residuals from Daqing, Shengli and Baise oilfields were analyzed. More than 100 individual target compounds including straight-and branched-chain alkanes (n-alkanes, pristane and phytane), polycyclic aromatic hydrocarbons (PAHs), terpanes, steranes and triaromatic steranes (TAS) in residual oil were determined by gas chromatography-mass spectrometry (GC-MS). For all the soil samples, less than 10% and 30% of alkanes and PAHs remained in the residual oils relative to crude oils. Terpanes, steranes and TAS were found to be less biodegradable. Depletions decreased with increasing carbon number of n-alkanes. However, average depletions > 80% were found in n-alkanes with carbon numbers < 37. Average depletions were > 70% for 2-4 ring PAHs, while 5-6 ring PAHs were more resistant. Increase in alkylation level decreased depletion within homologues of naphthalene, phenanthrene, chrysene and Benzo[e] pyrene. GC-MS could only reveal less than 3% of the compounds of residual oils, which were mainly comprised of n-alkanes with carbon number > 20, alkylated naphthalenes and phenanthrenes, terpanes, steranes and TAS. Based on compositional characteristics of alkanes and PAHs in residual oils, 6 diagnostic ratios, which were ratios of susceptible compounds to resistant compounds or to the amounts residual oil, were proposed as the parameters for characterization of residual oils and determining the biodegradability of oils contaminated soils. PMID:22720589

Wang, Jian; Zhang, Xu; Li, Guang-He

2012-04-01

10

Influence of diagnostic classification on gender ratio in schizophrenia  

Microsoft Academic Search

Background The research literature on hospital admissions for psychoses in youths was reviewed in order to test whether there was a gender ratio discrepancy in diagnostic subgroups; the effect of the diagnostic criteria classification on this measure was also investigated. Method A meta-analysis was conducted on 12 primary studies by assessing the male\\/female odds ratio (OR) in the schizophrenia and

Guy Beauchamp; André Gagnon

2004-01-01

11

Herschel Pacs Spectroscopy Of Stephan's Quintet: Extreme C+/pah Ratio In The Shocked Gas  

NASA Astrophysics Data System (ADS)

Spectroscopy observations of the giant shocked filament in Stephan's Quintet by the Spitzer Space Telescope revealed powerful emission from warm molecular hydrogen lines which dominated the line cooling in the mid-IR, and were too powerful to have been formed in PDRs. Our team has now performed Herschel PACS spectroscopy of the shock, and has found, 1) extremely large ratios of C+/PAH > 1 in regions throughout the shock inconsistent with photoelectric heating, and 2) weak or undetected [OI]63 micron and H$_2$O line emission. Contrary to initial expectations that shock-driven C+ would be weak in galaxy-scale shocks, the results suggest that a huge network of low-velocity magnetic C-shocks in a highly turbulent medium is responsible for both the C+ and the warm H$_2$ emission. The results may have implications for the interpretation of molecular and C+ emission from high-z galaxies if turbulence and low-velocity shocks dissipate energy as gas accretes onto DM halos.

Appleton, Philip N.; Guillard, P.; Cluver, M.; Boulanger, F.; Ogle, P.; Strurm, E.; Herschel OT1 pappleto 1 Team

2012-05-01

12

Concentration and composition of polycyclic aromatic hydrocarbons (PAHs) in plastic pellets: implications for small-scale diagnostic and environmental monitoring.  

PubMed

Plastic pellets may serve as a carrier of toxic contaminants, including polycyclic aromatic hydrocarbons (PAHs). Considering that beach morphodynamics and pellet distribution varied along the shore, and that contaminant sources may vary on different scales, it is expected that this variability is reflected in the concentration and composition of contaminants. This hypothesis was tested through a sampling of plastic pellets at 30 sites along the shore in Santos Bay (Brazil). The total PAH concentrations and the priority PAHs showed high variability, with no clear pattern. Their composition differed among the sampling sites; some of the compounds represent a potential risk to organisms. The sources of contamination, as indicated by the isomer ratios, were also variable among sites. The high small-scale spatial variability found here has implications for estimating the plastic pellet contamination on beaches, since a sample from a single site is unlikely to be representative of an entire beach. PMID:24125130

Fisner, Mara; Taniguchi, Satie; Majer, Alessandra P; Bícego, Márcia C; Turra, Alexander

2013-11-15

13

Development of novel fuel ion ratio diagnostic techniques  

Microsoft Academic Search

To overcome the challenge of measuring the fuel ion ratio in the core (rho<0.3) of ITER, a coordinated effort aiming at developing diagnostic techniques has been initiated. The investigated techniques are novel uses or further development of existing methods such as charge exchange recombination spectrometry, neutron spectrometry, and collective Thomson scattering. An overview of the work on the three diagnostic

S. B. Korsholm; M. Stejner; S. Conroy; G. Ericsson; G. Gorini; M. Tardocchi; MG von Hellermann; R. J. E. Jaspers; O. Lischtschenko; EG Delabie; H. Bindslev; V. Furtula; F. Leipold; F. Meo; P. K. Michelsen; D. Moseev; S. K. Nielsen; M. Salewski

2010-01-01

14

Source apportionment of polycyclic aromatic hydrocarbons in surface sediment of mud areas in the East China Sea using diagnostic ratios and factor analysis.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) and aliphatic hydrocarbons (AHs) have been quantified for surface sediments collected from the East China Sea (ECS). Our results showed that relatively high levels of PAHs and AHs occurred in both the inner and outer mud areas, while their concentrations at the control site were much lower. AHs for all samples were dominated by the unresolved complex mixture (UCM). Results from diagnostic ratios revealed that sedimentary PAHs were mainly originated from mixed combustion residues of biomass, coal, and petroleum. Combustion residues of petroleum and oil were responsible for the presence of high AHs concentrations. We also conducted factor analysis (FA) to further characterize the PAH and AH sources. Four factors were identified based on the loading of components and attributed to coal and wood combustion (Factor 1), traffic-related sources (Factor 2), petrogenic source (Factor 3) and natural gas combustion (Factor 4). PMID:23541289

Deng, Wei; Li, Xian Guo; Li, Sheng Yong; Ma, Yan Yan; Zhang, Da Hai

2013-05-15

15

Temperature diagnostic line ratios of Fe XVII. [of Sun  

NASA Technical Reports Server (NTRS)

Based on extensive calculations of the excitation rates of Fe XVII, four temperature-sensitive line ratios are investigated, paying special attention to the contribution of resonances to the excitation rates and to the contributions of dielectronic recombination satellites to the observed line intensities. The predictions are compared to FPCS observations of Puppis A and to Solar Maximum Mission (SMM) and SOLEX observations of the sun. Temperature-sensitive line ratios are also computed for emitting gas covering a broad temperature range. It is found that each ratio yields a differently weighted average for the temperature and that this accounts for some apparent discrepancies between the theoretical ratios and solar observations. The effects of this weighting on the Fe XVII temperature diagnostics and on the analogous Fe XXIV/Fe XXV satellite line temperature diagnostics are discussed.

Raymond, J. C.; Smith, B. W.

1986-01-01

16

Concentration, origin and health hazard from fine particle-bound PAH at three characteristic sites in Southern Poland.  

PubMed

Suspended particles with the aerodynamic diameters not greater than 2.5 ?m (PM2.5) and 1 ?m (PM1, sub-fraction of PM2.5) were sampled at three sites: an urban background site, rural background site, and urban traffic site in southern Poland. In total, there were 240 samples taken within 02.08.2009-27.12.2010. Fifteen polycyclic aromatic hydrocarbons (PAH) were determined in each dust fraction. The averages of the concentration of total PAH (?PAH) and of particular PAH, as well as the share of carcinogenic PAH in total PAH (?PAHcarc/?PAH), carcinogenic equivalent, mutagenic equivalent, and TCDD-toxic equivalent appeared high compared to other areas in the world. Their high values express the significance of health hazard from PM and PM-bound PAH in southern Poland. The diagnostic ratios suggest that PM-bound PAH originate from municipal (PM1-2.5) and vehicular (PM1) combustion. PMID:23877624

Rogula-Koz?owska, Wioletta; Kozielska, Barbara; Klejnowski, Krzysztof

2013-09-01

17

Sediment PAH: Contrasting levels in the Caspian Sea and Anzali Wetland.  

PubMed

A comparative study of 23 PAH congeners in sediment of the Caspian Sea coast and Anzali Wetland was conducted in 2010. Surface sediment was analyzed using chromatography and mass spectrometry. Total PAH concentrations ranged between 212 and 9009ngg(-)(1)dw. Spatial distribution maps revealed that PAH levels were higher in the coastal areas of the Caspian Sea where oil related activities have been common since 1800's. Diagnostic ratios analysis indicated that PAHs largely originated from petrogenic processes. PAH toxicity level was assessed using sediment quality guidelines and toxic equivalent concentrations to determine toxic effects on marine organism. Based on these investigations, in our study areas, the probability of toxicity for benthic organisms is "low to medium". The toxic equivalent concentrations of carcinogenic PAHs varied between 11 and 231ng TEQ/g; higher total toxic equivalent concentrations values were found in the coastal areas of the Caspian Sea. PMID:24910181

Yancheshmeh, Rokhsareh Azimi; Bakhtiari, Alireza Riyahi; Mortazavi, Samar; Savabieasfahani, Mozhgan

2014-07-15

18

Laboratory Astrochemistry: Interstellar PAHs  

NASA Technical Reports Server (NTRS)

Polycyclic aromatic hydrocarbons (PAHs) are now considered to be an important and ubiquitous component of the organic material in space. PAHs are found in a large variety of extraterrestrial materials such as interplanetary dust particles (IDPs) and meteoritic materials. PAHs are also good candidates to account for the infrared emission bands (UIRs) and the diffuse interstellar optical absorption bands (DIBs) detected in various regions of the interstellar medium. The recent observations made with the Infrared Space Observatory (ISO) have confirmed the ubiquitous nature of the UIR bands and their carriers. PAHs are thought to form through chemical reactions in the outflow from carbon-rich stars in a process similar to soot formation. Once injected in the interstellar medium, PAHs are further processed by the interstellar radiation field, interstellar shocks and energetic particles. A major, dedicated, laboratory effort has been undertaken to measure the physical and chemical characteristics of these complex molecules and their ions under experimental conditions that mimic the interstellar conditions. These measurements require collision-free conditions where the molecules and ions are cold and chemically isolated. The spectroscopy of PAHs under controlled conditions represents an essential diagnostic tool to study the evolution of extraterrestrial PAHs. The Astrochemistry Laboratory program will be discussed through its multiple aspects: (1) objectives, (2) approach and techniques adopted, (3) adaptability to the nature of the problem(s), and (4) results and implications for astronomy as well as for molecular spectroscopy. A review of the data generated through laboratory simulations of space environments and the role these data have played in our current understanding of the properties of interstellar PAHs will be presented. The discussion will also introduce the newest generation of laboratory experiments that are currently being developed in order to provide a closer simulation of space environments and a better support to space missions.

Salama, Farid; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

19

Rotational spectroscopy of interstellar PAHs  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbons (PAHs) are believed to be ubiquitous in the interstellar medium. Yet, to date no specific PAH molecule has been identified. In this paper, a new observational avenue is suggested to detect individual PAHs, using their rotational line emission at radio frequencies. Previous PAH searches based on rotational spectroscopy have only targeted the bowl-shaped corannulene molecule, with the underlying assumption that other polar PAHs are triaxial and have a complex and diluted spectrum unusable for identification purposes. In this paper, the rotational spectrum of quasi-symmetric PAHs is computed analytically. It is shown that the asymmetry of planar, nitrogen-substituted symmetric PAHs is small enough that their rotational spectrum, when observed with a resolution of about a MHz, has the appearance of a `comb' of evenly spaced stacks of lines. The simple pattern of these `comb' spectra allows for the use of matched-filtering techniques, which can result in a significantly enhanced signal-to-noise ratio. Detection forecasts are discussed for regions harbouring `anomalous microwave emission', believed to originate from the collective PAH rotational emission. A systematic search for PAH lines in various environments is advocated. If detected, PAH `combs' would lead us to the conclusive and unambiguous identification of specific, free-floating interstellar PAHs.

Ali-Haïmoud, Yacine

2014-01-01

20

Spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere of Xiamen, China.  

PubMed

An intensive sampling program was conducted from October 2008 to September 2009 at the five different environmental sites in Xiamen, Fujian Province, to study the spatial and temporal characteristics of Polycyclic Aromatic Hydrocarbons (PAHs) in the gaseous and particulate phase, respectively. The PAHs concentrations at different sites were quite distinct during four seasons. The average concentrations of PAHs in winter were about 8.4 times higher than those in spring, and the concentrations of background were 0.56 times lower than those of industrial area. In addition, the higher temperature in summer affected the particle/gas partitioning of PAHs and led to the higher concentrations of gaseous PAHs. Diagnostic ratios of PAHs, which were employed to indicate the primary sources of PAHs in Xiamen, showed that the traffic vehicle exhaust was the largest contributor and the primary source for PAHs in Xiamen, especially in urban area; while the stationary combustion processes, such as petrochemical factories and power plants, were mainly responsible for PAHs sources in the industrial areas. The health risk of PAHs in the particulate phase was higher than those of the gaseous phase at the five sampling sites. The average toxic equivalent (BaPeq) of the benzo[a]pyrene values for PAHs were 0.14, 0.32, 1.38 and 3.59 ng m(-3) in spring, summer, autumn and winter, respectively. Furthermore, the results of average BaPeq in all four seasons indicated that the health risks of particulate PAHs were higher than those of the gaseous PAHs at different sampling sites. PMID:21944198

Zhao, Jinping; Zhang, Fuwang; Xu, Lingling; Chen, Jinsheng; Xu, Ya

2011-11-15

21

[Size distribution of polycyclic aromatic hydrocarbons (PAHs) in different function zones of Guangzhou in autumn, China].  

PubMed

Size distribution of aerosol samples collected from two urban locations (Liwan and Wushan) and a suburban location (Xinken) in Guangzhou (South China) in autumn using Micro-Orifice Uniform Deposit Impactor (MOUDI) were analyzed for 13 polycyclic aromatic hydrocarbons (PAHs) by gas chromatography with mass selective detection (GC-MS). Bimodal distribution was found for 3- and 4-ring PAHs and unimodal for 5-, 6- and 7-ring PAHs. Different PAH size distribution models were found for urban and suburban. PAHs associated with larger particles in suburban than in urban, and different aging processes of aerosols can account for it. Adsorption behavior may be the main mechanism controlled the size distribution of PAHs in urban, and adsorption, absorption and multilayer adsorption may all play a part in suburban. For the diagnostic ratios of PAHs with the same molecular weight, large differences were found between the range of 1-2.5 microm and 0.1-0.56 microm. The concentrations of 13 PAHs were 39 ng/m3 in Xinken, 71-94 ng/m3 in Wushan and 32-154 ng/m3 in Liwan, and 5-7 ring PAHs were the most abundant. PMID:16767976

Duan, Jing-chun; Bi, Xin-hui; Tan, Ji-hua; Sheng, Guo-ying; Fu, Jia-mo; Hao, Ji-ming

2006-04-01

22

Characterization of the size-distribution of aerosols and particle-bound content of oxygenated PAHs, PAHs, and n-alkanes in urban environments in Afghanistan  

NASA Astrophysics Data System (ADS)

Air pollution is a common problem in mega-cities in Asia, resulting in high levels of particulate matter (PM). In this study, 24 h samples of airborne particulate matter (PM 2.5 and PM 10) was collected for two weeks in urban locations in Kabul and Mazar-e Sharif, Afghanistan. The samples were analyzed for twenty n-alkanes, fifteen polycyclic aromatic hydrocarbons (PAHs) and eighteen oxygenated PAHs (oxy-PAHs). The results were compared to a reference location in Umeå, Sweden. The main objectives were: to characterize the organic fraction in PM 2.5, with focus on oxy-PAHs, PAHs and n-alkanes, assess relationships between compound groups, and investigate possible source categories. Mean PM 10, levels were 260 ?g m -3, and 334 ?g m -3 and mean PM 2.5 levels were 86 ?g/m 3and 68 ?g m -3 in Kabul and Mazar-e Sharif, respectively. The higher ratio of PM 2.5 to PM 10 in Kabul than Mazar-e Sharif or Umeå was reflected in the high number of small particles, as collected by a particle counter. Kabul and Mazar-e Sharif had high levels of PAHs and oxy-PAHs compared to Umeå and previously reported data from Western countries. Generally, the highest individual levels of oxy-PAHs were found for ketones (0.27-33 ng m -3), whereas the quinone levels were lower (0.027-3.1 ng m -3). High correlations ( r > 0.96) between PAHs and oxy-PAHs were found at both locations. Diagnostics for n-alkanes, such as the carbon preference index, and the most abundant species, Cmax, and the presence of unresolved complex mixture indicated a higher contribution from coal and petroleum sources in Kabul. Models generated by principal component analysis (PCA) and positive matrix factorization (PMF) both suggested separate sources for lower molecular weight n-alkanes and higher molecular weight n-alkanes. The PAHs and the oxy-PAHs were not separated in either the PCA or the PMF models, indicating that they had similar sources and are perhaps relatively unspecific as source markers. Nevertheless, the PAHs and oxy-PAHs were good markers for bad air quality in the urban locations in Afghanistan in comparison to data from Western countries. Based on the models and diagnostic ratios it is suggested that traffic and combustion of coal and biomass were the dominating sources of the high levels of particle-bound organic compounds.

Wingfors, Håkan; Hägglund, Lars; Magnusson, Roger

2011-08-01

23

Relationship between polycyclic aromatic hydrocarbons (PAHs) and particle size in dated core sediments in Lake Lianhuan, Northeast China.  

PubMed

Atmospheric particle associated with pyrogenic polycyclic aromatic hydrocarbons (PAHs) poses serious threats to human health by inhalation exposure, especially in semiarid areas. Hence, the distributions of PAHs and particle size in two core sediments collected from Lake Lianhuan, Northeast China were studied. The sediments were dated radiometrically, and particle size distribution and PAH concentration were evaluated and potential human health risk was assessed. From 1980 to 2007, the dominant PAHs in the two cores were 2- and 3-ring PAHs, and the concentrations of 3-6 ring PAHs gradually increased from the early 1990s. Diagnostic ratios indicated that pyrogenic PAHs were the main sources of PAHs which changed over time from combustions of wood and coal to liquid fossil fuel sources. Fine particles (<65 ?m) were the predominant particle size (56-97%). Lacustrine source (with the peak towards 200-400 ?m) and eolian sources derived from short (2.0-10 and 30-65 ?m) and long (0.4-1.0 ?m) distance suspension were indentified from frequency distribution pattern of particle size. Significant correlations between 3-6 ring PAHs (especially carcinogenic 5-6 ring PAHs) and 10-35 ?m particulate fractions indicated that eolian particles played an important role in adsorbing pyrogenic PAHs. Petroleum source of PAHs was only identified during the 1980s in one core sediments, in which positive correlations between 2-ring PAHs and particulate fractions of >125 ?m were found. Future research should focus on the seven carcinogenic pyrogenic PAHs due to a rapidly increasing trend since 1995 based on the assessment of toxic equivalency factors. PMID:23727602

Sun, Li; Zang, Shuying

2013-09-01

24

Fate of PCBs, PAHs and their source characteristic ratios during composting and digestion of source-separated organic waste in full-scale plants  

Microsoft Academic Search

Composting and digestion are important waste management strategies. However, the resulting products can contain significant amounts of organic pollutants such as polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). In this study we followed the concentration changes of PCBs and PAHs during composting and digestion on field-scale for the first time. Concentrations of low-chlorinated PCBs increased during composting (about 30%),

Rahel C. Brändli; Thomas D. Bucheli; Thomas Kupper; Jochen Mayer; Franz X. Stadelmann; Joseph Tarradellas

2007-01-01

25

Source seasonality of polycyclic aromatic hydrocarbons (PAHs) in a subtropical city, Guangzhou, South China.  

PubMed

Mega-cities are large sources of air pollution on a regional base. Differences in energy structures, geographical settings and regional climate features lead to a large variety of air pollution sources from place to place. To understand the seasonality of air pollution sources is critical to precise emission inventories and a sound protection of human health. Based on a year-round dataset, the sources of PAHs in the air of Guangzhou were drawn by principal factor analysis (PCA) in combination with diagnostic ratios, and the seasonality of these sources were analyzed by PCA/MLR (multiple linear regressions) and discussed. The average total gaseous and particulate PAHs concentrations were 313 and 23.7 ng m(-3), respectively, with a higher concentration of vapor PAHs in summer and particulate PAHs in winter. In addition to vehicle exhaust, which contributed 69% of the particulate PAHs, coal combustion was still an important source and contributed 31% of the particulate PAHs. Relatively constant contribution from coal combustion was found through the year, implying that coal combustion in power plants was not a seasonally dependent source. Evaporation from contaminated ground may be an important source of light PAHs in summer, providing an average contribution of 68% to the total PAHs in this study. By comparing the PAH concentrations and meteorological parameters, we found that higher concentrations of particulate PAHs in winter resulted from enhanced vehicle exhaust under low temperature and accumulation of pollutants under decreased boundary layer, slower wind speed, and long-term dryness conditions. It is suggested that the typical subtropical monsoon climate in South China, cool and dry in winter, hot and humid in summer, may play a key role in controlling the source seasonality (by enhancing vehicle exhaust in winter, ground evaporation in summer), and hence the ambient concentrations of PAHs in the air. PMID:16137742

Li, J; Zhang, G; Li, X D; Qi, S H; Liu, G Q; Peng, X Z

2006-02-15

26

Polycyclic aromatic hydrocarbons (PAHs) in soils from a multi-industrial city, South Korea.  

PubMed

We collected soil samples at 25 sites in Ulsan, Korea to investigate the levels, patterns, spatial distribution, and sources of polycyclic aromatic hydrocarbons (PAHs) in the summer 2010. The target compounds were the 16 US-EPA priority PAHs. For the source identification of PAHs, diagnostic ratios and the positive matrix factorization (PMF) model were used. The total concentrations of PAHs ranged from 65 ng/g to 12,000 ng/g (mean: 960 ng/g, median 330 ng/g). The levels and distribution of PAHs indicated that industrial areas were more polluted than rural and urban areas. The diagnostic ratios suggested that the soil samples were contaminated by pyrogenic sources and traffic emission. According to the result of PMF, four factors were identified: gasoline and heavy oil combustion (14%), diesel combustion (54%), coke oven (23%), and coal/biomass burning (9%). Therefore, it was concluded that vehicles and industrial complexes were major sources of PAHs in Ulsan. PMID:24011990

Kwon, Hye-Ok; Choi, Sung-Deuk

2014-02-01

27

Spatial distribution and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in Camphor (Cinnamomum camphora) tree bark from Southern Jiangsu, China.  

PubMed

The concentrations and sources of polycyclic aromatic hydrocarbons (PAHs) were investigated in Camphor tree bark from Southern Jiangsu, China. Tree bark samples were collected in August 2012. The ?15PAHs concentrations were ranged from 6.18 to 1560 ng g(-1)dry weight (dw), with an average value of 407 ng g(-1)dw. Generally, the concentrations of PAHs in the suburban areas were the highest, followed by urban and rural areas. Principal component analysis and diagnostic ratios results showed that vehicle emission, biomass and coal combustion and industrial emission were the major sources of PAHs in tree bark from Southern Jiangsu. Good correlation was found between tree bark and polyurethane foam (PUF) samplers, indicating that both of them respond well to the gas-phase PAHs monitoring. PMID:24480428

Zhou, Li; Dong, Liang; Huang, Yeru; Shi, Shuangxin; Zhang, Lifei; Zhang, Xiulan; Yang, Wenlong; Li, Lingling

2014-07-01

28

Near infrared hydrogen emission line ratios as diagnostics of the broad emission line region  

NASA Astrophysics Data System (ADS)

Broad emission line flux ratios are a powerful diagnostic of the physical conditions of the broad-line region gas in Active Galactic Nuclei. With recent advances in infrared spectroscopy, previously unstudied emission lines provide a new means to investigate the physical nature of the BELR gas. The hydrogen emission lines are particularly sensitive to the upper limits of both the radius from the central ionising source and the number density of the gas. Using an existing subset of near-infrared quasar spectra from the Glikman et al. (2006) sample [1] together with Cloudy photoionization simulations, we confirm the Locally Optimally emitting Cloud (LOC) model's ability to reproduce observed emission line flux ratios. The model is then used to constrain physical conditions for individual sources. The photoionization models show that high number density, low incident flux gas is required to reproduce observed near-infrared hydrogen emission line ratios. We also find that comparison to individual sources, rather than composites, is vital.

Ruff, Andrea J.; Floyd, David J. E.; Korista, Kirk T.; Webster, Rachel L.; Porter, Ryan L.; Ferland, Gary J.

2012-07-01

29

Method development for forensic identification of biodiesel based on chemical fingerprints and corresponding diagnostic ratios.  

PubMed

A forensic identification method based on the chemical fingerprinting of the first generation of biodiesel (fatty acid alkyl esters as effective components), and several corresponding diagnostic ratios was developed and validated. The distribution of major fatty acid methyl esters (FAMEs) and polar compounds (free fatty acids, glycerol, monoacylglycerides, and free sterols) in several representative above biodiesel products commercially available in Canada were positively quantified and compared, a number of cross-plots of diagnostic ratios of target FAMEs and sterols were developed for biofuel correlation and differentiation. It was found that the cross-plots of FAME ratios, for example, the sum of the di-unsaturated relative to saturated homologues of FAMEs (D/S) versus the sum of the mono-saturated to saturated FAMEs (M/S), and the sum of di-unsaturated to mono-saturated FAMEs (D/M) versus the sum of the mono-saturated to saturated FAMEs (M/S), could cluster samples clearly into their individual feedstock. The cross-plots of diagnostic ratios of individual major sterols (cholesterol, brassicasterol, campesterol, ?-stiosterol and stigmasterol) to the total sterols were also developed and proved to be effective in identifying biodiesel sources due to their self-normalizing effect on sterol data. The case study of a mystery biodiesel spill using this method showed that the two real samples can be tightly clustered into biodiesel from animal fat (Ban) group. However, the significant discrepancy of free fatty acids, glycerol, monoacylglycerides and sterol concentrations between the two real samples indicated their different producing batches. PMID:24378307

Yang, Zeyu; Hollebone, Bruce P; Wang, Zhendi; Yang, Chun; Brown, Carl; Landriault, Mike

2014-01-01

30

Laboratory Astrochemistry: Interstellar PAH Analogs  

NASA Technical Reports Server (NTRS)

Polycyclic aromatic hydrocarbons (PAHs) are now considered to be an important and ubiquitous component of the organic material in space. PAHs are found in a large variety of extraterrestrial materials such as interplanetary dust particles (IDPs) and meteoritic materials. PAHs are also good candidates to account for the infrared emission bands (UIRs) and the diffuse interstellar optical absorption bands (DIBs) detected in various regions of the interstellar medium. The recent observations made with the Infrared Space Observatory (ISO) have confirmed the ubiquitous nature of the UIR bands and their carriers. PAHs are though to form through chemical reactions in the outflow from carbon-rich stars in a process similar to soot formation. Once injected in the interstellar medium, PAHs are further processed by the interstellar radiation field, interstellar shocks and energetic particles. A major, dedicated, laboratory effort has been undertaken over the past years to measure the physical and chemical characteristics of these complex molecules and their ions under experimental conditions that mimic the interstellar conditions. These measurements require collision-free conditions where the molecules and ions are cold and chemically isolated. The spectroscopy of PAHs under controlled conditions represents an essential diagnostic tool to study the evolution of extraterrestrial PAHs. The Astrochemistry Laboratory program will be discussed through its multiple aspects: objectives, approach and techniques adopted, adaptability to the nature of the problem(s), results and implications for astronomy as well as for molecular spectroscopy. A review of the data generated through laboratory simulations of space environments and the role these data have played in our current understanding of the properties of interstellar PAHs will be presented. The discussion will also introduce the newest generation of laboratory experiments that are currently being developed in order to provide a closer simulation of space environments and a better support to space missions.

Salama, Farid; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

31

Sequential Binary Gene-Ratio Tests Define a Novel Molecular Diagnostic Strategy for Malignant Pleural Mesothelioma  

PubMed Central

Purpose To develop a standardized approach for molecular diagnostics, we used the gene-expression ratio bioinformatic technique to design a molecular signature to diagnose MPM from among other potentially confounding diagnoses and differentiate the epithelioid from the sarcomatoid histological subtype of MPM. In addition, we searched for pathways relevant in MPM in comparison to other related cancers to identify unique molecular features in MPM. Experimental Design We performed microarray analysis on 113 specimens including MPMs and a spectrum of tumors and benign tissues comprising the differential diagnosis of MPM. We generated a sequential combination of binary gene-expression ratio tests able to discriminate MPM from other thoracic malignancies. We compared this method to other bioinformatic tools and validated this signature in an independent set of 170 samples. Functional enrichment analysis was performed to identify differentially expressed probes. Results A sequential combination of gene-expression ratio tests was the best molecular approach to distinguish MPM from all the other samples. Bioinformatic and molecular validations showed that the sequential gene ratio tests were able to identify the MPM samples with high sensitivity and specificity. In addition, the gene-ratio technique was able to differentiate the epithelioid from the sarcomatoid type of MPM. Novel genes and pathways specifically activated in MPM were identified. Conclusions New clinically relevant molecular tests have been generated using a small number of genes to accurately distinguish MPMs from other thoracic samples supporting our hypothesis that the gene-expression ratio approach could be a useful tool in the differential diagnosis of cancers.

De Rienzo, Assunta; Richards, William G.; Yeap, Beow Y.; Coleman, Melissa H.; Sugarbaker, Peter; Chirieac, Lucian R.; Wang, Yaoyu E.; Quackenbush, John; Jensen, Roderick V.; Bueno, Raphael

2013-01-01

32

Diagnostic accuracy of urinary spot protein:creatinine ratio for proteinuria in hypertensive pregnant women: systematic review  

Microsoft Academic Search

Objective To review the spot protein:creatinine ratio and albumin:creatinine ratio as diagnostic tests for significant proteinuria in hypertensive pregnant women.Design Systematic review.Data sources Medline and Embase, the Cochrane Library, reference lists, and experts.Review methods Literature search (1980-2007) for articles of the spot protein:creatinine ratio or albumin:creatinine ratio in hypertensive pregnancy, with 24 hour proteinuria as the comparator.Results 13 studies concerned

Anne-Marie Côté; Mark A Brown; Elaine Lam; Peter von Dadelszen; Tabassum Firoz; Robert M Liston; Laura A Magee

2008-01-01

33

Transboundary movement of polycyclic aromatic hydrocarbons (PAHs) in the Kuroshio Sphere of the western Pacific Ocean  

NASA Astrophysics Data System (ADS)

Atmospheric PAHs in the Kuroshio Sphere of southern Taiwan were measured and characterized using samples collected simultaneously at four sites from February to October in 2007. Higher PAH concentrations occurred in winter (range 2.41 ± 1.85 to 40.8 ± 6.97 ng m-3) and autumn (range 1.21 ± 0.32 to 65.1 ± 57.4 ng m-3) than in summer (range 0.87 ± 0.36 to 17.7 ± 2.88 ng m-3). Comparison of the total PAH concentrations from the four sampling sites showed that the total PAH concentrations from the Kaohsiung urban site (KHU) were 1.7-4.4 times higher than those from the Kaohsiung coastal site (KHC), 3.6-26 times those from a rural coastal site (Kenting, KT), and 16.9-53.8 times those from an offshore island site (Lanyu, LY). The PAH compositional pattern, diagnostic ratios and principal component analysis indicated that the major sources of PAHs in the study area can be classified into three categories. The first is vehicular sources from local traffic, the second is natural soils, and the third is industrial activities including coke ovens and incinerator emissions. The results from back trajectories also demonstrated that atmospheric PAHs were produced by local sources but were also influenced by transboundary movement of terrestrial pollutants. The characteristics and sources of atmospheric PAHs identified in this study provide useful information for estimating the effects and transportation of PAHs in the Kuroshio Sphere.

Huang, Hu-Ching; Lee, Chon-Lin; Lai, Chin-Hsing; Fang, Meng-Der; Lai, I.-Chien

2012-07-01

34

PAHs in Translucent Interstellar Clouds  

NASA Astrophysics Data System (ADS)

We discuss the proposal of relating the origin of some of the diffuse interstellar bands (DIBs) to neutral polycyclic aromatic hydrocarbons (PAHs) present in translucent interstellar clouds. The spectra of several cold, isolated gas-phase PAHs have been measured in the laboratory under experimental conditions that mimic the interstellar conditions and are compared with an extensive set of astronomical spectra of reddened, early type stars. This comparison provides - for the first time - accurate upper limits for the abundances of specific PAH molecules along specific lines-of-sight. Something that is not attainable from IR observations alone. The comparison of these unique laboratory data with high resolution, high S/N ratio astronomical observations leads to two major findings: (1) a finding specific to the individual molecules that were probed in this study and, which leads to the clear and unambiguous conclusion that the abundance of these specific neutral PAHs must be very low in the individual translucent interstellar clouds that were probed in this survey (PAH features remain below the level of detection) and, (2) a general finding that neutral PAHs exhibit intrinsic band profiles that are similar to the profile of the narrow DIBs indicating that the carriers of the narrow DIBs must have close molecular structure and characteristics. This study is the first quantitative survey of neutral PAHs in the optical range and it opens the way for unambiguous quantitative searches of PAHs in a variety of interstellar and circumstellar environments. // Reference: F. Salama et al. (2011) ApJ. 728 (1), 154 // Acknowledgements: F.S. acknowledges the support of the NASA's Space Mission Directorate APRA Program. J.K. acknowledges the financial support of the Polish State (grant N203 012 32/1550). The authors are deeply grateful to the ESO archive as well as to the ESO staff members for their active support.

Salama, Farid; Galazutdinov, G.; Krelowski, J.; Biennier, L.; Beletsky, Y.; Song, I.

2011-05-01

35

Temporal and spatial variations in PAH concentrations in the sediment from the Nilufer Creek in Bursa, Turkey.  

PubMed

The objective of this study was to identify the temporal variations in PAH concentrations in the sediment at different locations on the Nilufer Creek moving along an industrial city. The distribution of various PAH species and their possible sources were determined. Sediment samples were taken from at eight different locations on the Nilufer Creek for a one-year period. Temporal concentration profiles were in the range of 15-9600 ng g(-1) dry matter (dm). PAH concentrations reached their maximum values in the winter (9600 ng g(-1) dm). Molecular diagnostic ratios of PAHs showed that the pollution in the Nilufer Creek in the fall, winter and summer seasons was mostly pyrolytic. It was observed that 3-4 ring species predominated in all seasons in the Nilufer Creek sediment. PMID:24766591

Karaca, Gizem; Tasdemir, Yücel

2014-07-01

36

Temporal trends of polycyclic aromatic hydrocarbons (PAHs) in Dreissena polymorpha specimens from Lake Maggiore (Northern Italy).  

PubMed

The Lake Maggiore (Northern Italy) has been recognized as an aquatic environment heavily contaminated by persistent organic pollutants, mainly organochlorine compounds, but to date limited information is available regarding another class of widespread and hazardous pollutants, such as the polycyclic aromatic hydrocarbons (PAHs). The aim of this study was to investigate seasonal and temporal trends of 18 PAHs accumulated in native Dreissena polymorpha specimens during a 5-year biomonitoring program, as well as to identify the possible PAH emission sources by using isomeric diagnostic ratios. Zebra mussels were sampled both in their pre- (May) and post-reproductive (September) stage over the 2008-2012 period in eight sampling stations covering the whole lake shoreline. PAH concentrations were measured through gas chromatography coupled to mass spectrometry. A notable PAH contamination following an increasing temporal trend was noticed in bivalves from all the sampling stations, with the benzo(?)anthracene as the predominant compound. An overall increase in PAH levels was found in the post-reproductive surveys, indicating a marked seasonality of this contamination probably due to the increase in touristic activity during spring-summer months. PMID:24532210

Parolini, Marco; Binelli, Andrea

2014-06-01

37

FE-XIII Infrared / FE-XIV Green Line Ratio Diagnostics (P55)  

NASA Astrophysics Data System (ADS)

aks.astro.itbhu@gmail.com We consider the first 27-level atomic model of Fe XIII (5.9 < log Te < 6.4 K) to estimate its ground level populations, taking account of electron as well as proton collisional excitations and de-excitations, radiative cascades, radiative excitations and de-excitations. Radiative cascade is important but the effect of dilution factor is negligible at higher electron densities. The 3 P1-3P0 and 3P2-3P1 transitions in the ground configuration 3s2 3p2 of Fe XIII result in two forbidden coronal emission lines in the infrared region, namely 10747 Å and 10798 Å., while the 5303 Å green line is formed in the 3s2 3p 2 2 ground configuration of Fe XIV as a result of P3 / 2 - P1 / 2 magnetic dipole transition. The line-widths of appropriate pair of forbidden coronal emission lines observed simultaneously can be useful diagnostic tool to deduce temperature and non-thermal velocity in the large scale coronal structures using intensity ratios of the lines as the temperature signature, instead of assuming ion temperature to be equal to the electron temperature. Since the line intensity ratios IG5303/IIR10747 and IG5303/IIR10798 have very week density dependence, they are ideal monitors of temperature mapping in the solar corona.

Srivastava, A. K.; et al.

2006-11-01

38

Deuterated PAHs in Space  

NASA Technical Reports Server (NTRS)

The cosmic deuterium to hydrogen (D/H) ratio is of key importance from a cosmological and stellar evolution perspective since deuterium originates from big-bang nucleosynthesis and is destroyed by stellar thermonuclear reactions. Further, from the interstellar perspective, the galactic distribution of deuterium and the D/H ratio among various molecular species also traces interstellar chemical evolution. Over the past few decades, radio observations have enabled the study of a handful of small, deuterated interstellar species. However, the number of deuterated species detected and environments probed are limited, raising issues of selection effects that hamper generalization and applications to other environments. Infrared spectroscopy of the interstellar medium offers a distinct advantage in this regard as the extent of deuteration of entire chemical families, rather than one species, can be probed. These observations require spaceborne telescopes because the molecular vibrations involving D which produce the strongest IR bands fall in spectral regions which are obscured by terrestrial CO2 absorption. Here we report the tentative detection of the C-D stretching vibration from deuterated interstellar polycyclic aromatic hydrocarbons in the Orion nebula. Since the PAH emission features are widespread and probe many different types of cosmic environments, follow up observations of deuterated PAHs will provide fundamental, far reaching new insight and perspective into galactic and extragalactic processes.

Peeters, Els; Allamandola, Louis J.; Bauschlicher, Charles W., Jr.; Hudgins, Douglas M.; Sandford, Scott A.; Tielens, A. G. G. M.; DeVincenzi, D. (Technical Monitor)

2002-01-01

39

PAH Spectra for Everyone  

NASA Astrophysics Data System (ADS)

The Ames Astrochemistry Laboratory now has PAH IR spectra of more than 220 laboratory measured and over 600 theoretically calculated IR spectra of polycyclic aromatic hydrocarbons (PAHs) in a multitude of forms. The vast majority of these spectra are not readily accessible to the public. We propose to make the full collection of the Ames experimental and computational collection of PAH IR spectra available to the entire Spitzer community and accessible via the World Wide Web (WWW). The laboratory measured mid-IR spectral collection includes over 220 neutral, cationic, and anionic PAHs, PAHs with deuterium in place of hydrogen, PAHs containing oxygen, and PAHs containing nitrogen (PANHs). The formulae of the PAHs in the experimental data collection range from C10H8 to C50H22. Unfortunately, it is not possible to obtain physical samples of all of the types of PAHs that are of astrophysical interest for experimental study. We also have an extensive collection of accurate computational spectra to fill in gaps in the experimentally available spectra. Our theoretical PAH spectral collection includes very large PAHs, PAHs containing 40 to 132 carbon atoms which are comparable to the size of the PAHs thought to dominate the interstellar emission spectrum. Large PAHs might be multiply charged and these are also represented in the theoretical database. There is also observational evidence for PAH cations with nitrogen in the inner rings (PANHs) and interest in the spectroscopy of aromatic species containing oxygen and deuterium as well as PAH metal clusters. All of these types of PAHs are represented in the Ames computational PAH IR spectroscopic collection. If funded, we plan to make our entire inventory of the lab spectra available to the Spitzer community within the next two years.

Allamandola, Louis; Bauschlicher, Charlie, Jr.; Mattioda, Andrew

2007-05-01

40

Ambient concentrations and personal exposure to polycyclic aromatic hydrocarbons (PAH) in an urban community with mixed sources of air pollution  

PubMed Central

Assessment of the health risks resulting from exposure to ambient polycyclic aromatic hydrocarbons (PAH) is limited by a lack of environmental exposure data among the general population. This study characterized personal exposure and ambient concentrations of PAH in the Village of Waterfront South (WFS), an urban community with many mixed sources of air toxics in Camden, New Jersey, and CopeWood/Davis Streets (CDS), an urban reference area located ~1 mile east of WFS. A total of 54 and 53 participants were recruited from non-smoking households in WFS and CDS, respectively. In all, 24-h personal and ambient air samples were collected simultaneously in both areas on weekdays and weekends during summer and winter. The ambient PAH concentrations in WFS were either significantly higher than or comparable to those in CDS, indicating the significant impact of local sources on PAH pollution in WFS. Analysis of diagnostic ratios and correlation suggested that diesel truck traffic, municipal waste combustion and industrial combustion were the major sources in WFS. In such an area, ambient air pollution contributed significantly to personal PAH exposure, explaining 44–96% of variability in personal concentrations. This study provides valuable data for examining the impact of local ambient PAH pollution on personal exposure and therefore potential health risks associated with environmental PAH pollution.

ZHU, XIANLEI; FAN, ZHIHUA (TINA); WU, XIANGMEI; JUNG, KYUNG HWA; OHMAN-STRICKLAND, PAMELA; BONANNO, LINDA J.; LIOY, PAUL J.

2014-01-01

41

PAH air pollution at a Portuguese urban area: carcinogenic risks and sources identification.  

PubMed

This study aimed to characterize air pollution and the associated carcinogenic risks of polycyclic aromatic hydrocarbon (PAHs) at an urban site, to identify possible emission sources of PAHs using several statistical methodologies, and to analyze the influence of other air pollutants and meteorological variables on PAH concentrations.The air quality and meteorological data were collected in Oporto, the second largest city of Portugal. Eighteen PAHs (the 16 PAHs considered by United States Environment Protection Agency (USEPA) as priority pollutants, dibenzo[a,l]pyrene, and benzo[j]fluoranthene) were collected daily for 24 h in air (gas phase and in particles) during 40 consecutive days in November and December 2008 by constant low-flow samplers and using polytetrafluoroethylene (PTFE) membrane filters for particulate (PM10 and PM2.5 bound) PAHs and pre-cleaned polyurethane foam plugs for gaseous compounds. The other monitored air pollutants were SO2, PM10, NO2, CO, and O3; the meteorological variables were temperature, relative humidity, wind speed, total precipitation, and solar radiation. Benzo[a]pyrene reached a mean concentration of 2.02 ng?m(-3), surpassing the EU annual limit value. The target carcinogenic risks were equal than the health-based guideline level set by USEPA (10(-6)) at the studied site, with the cancer risks of eight PAHs reaching senior levels of 9.98 × 10(-7) in PM10 and 1.06 × 10(-6) in air. The applied statistical methods, correlation matrix, cluster analysis, and principal component analysis, were in agreement in the grouping of the PAHs. The groups were formed according to their chemical structure (number of rings), phase distribution, and emission sources. PAH diagnostic ratios were also calculated to evaluate the main emission sources. Diesel vehicular emissions were the major source of PAHs at the studied site. Besides that source, emissions from residential heating and oil refinery were identified to contribute to PAH levels at the respective area. Additionally, principal component regression indicated that SO2, NO2, PM10, CO, and solar radiation had positive correlation with PAHs concentrations, while O3, temperature, relative humidity, and wind speed were negatively correlated. PMID:23184127

Slezakova, K; Pires, J C M; Castro, D; Alvim-Ferraz, M C M; Delerue-Matos, C; Morais, S; Pereira, M C

2013-06-01

42

PAHs (polycyclic aromatic hydrocarbons), nitro-PAHs, and hopane and sterane biomarkers in sediments of southern Lake Michigan, USA.  

PubMed

PAHs in the Great Lakes basin are of concern due to their toxicity and persistence in bottom sediments. Their nitro derivatives, nitro-PAHs (NPAHs), which can have stronger carcinogenic and mutagenic activity than parent PAHs, may follow similar transport routes and also are accumulated in sediments. Limited information exists regarding the current distribution, trends and loadings of these compounds, especially NPAHs, in Lake Michigan sediments. This study characterizes PAHs, NPAHs, and biomarkers steranes and hopanes in surface sediments collected at 24 offshore sites in southern Lake Michigan. The ?PAH14 (sum of 14 compounds) ranged from 213 to 1,291 ng/g dry weight (dw) across the sites, levels that are 2 to 10 times lower than those reported 20 to 30 years earlier. Compared to consensus-based sediment quality guidelines, PAH concentrations suggest very low risk to benthic organisms. The ?NPAH5 concentration ranged from 2.9 to 18.6 ng/g dw, and included carcinogenic compounds 1-nitropyrene and 6-nitrochrysene. ?Sterane6 and ?Hopane5 concentrations ranged from 6.2 to 36 and 98 to 355 ng/g dw, respectively. Based on these concentrations, Lake Michigan is approximately receiving 11, 0.16, 0.25 and 3.6 metrictons per year (t/yr) of ?PAH14, ?NPAH5, ?Sterane6 and ?Hopane5, respectively. Maps of OC-adjusted concentrations display that concentrations decline with increasing off-shore distance. The major sources of PAHs and NPAHs are pyrogenic in nature, based on diagnostic ratios. Using chemical mass balance models, sources were apportioned to emissions from diesel engines (56 ± 18%), coal power plants (27 ± 14%), coal-tar pavement sealants (16 ± 11%), and coke ovens (7 ± 12%). The biomarkers identify a combination of petrogenic and biogenic sources, with the southern end of the lake more impacted by petroleum. This first report of NPAH levels in sediments of Lake Michigan reveals several carcinogenic compounds at modest concentrations, and a need for further work to assess potential risks to aquatic organisms. PMID:24784742

Huang, Lei; Chernyak, Sergei M; Batterman, Stuart A

2014-07-15

43

Fe XXI Emission Line Ratios as Electron Temperature Diagnostics for the Coronae of Cool Stars  

NASA Astrophysics Data System (ADS)

Theoretical Fe xxi electron temperature and density sensitive emission line ratios are presented for R_1 = Ileft( {2s^2 2p^2 {}^3P_1 - 2s2p^3 {}^5S} right)/Ileft( {2s^2 2p^2 {}^3P_0 - 2s^2 2p^2 {}^3P_1 } right) and R_2 = Tleft( {2s^2 2p^2 {}^3P_1 - 2s2p^2 {}^1S} right)/Tleft( {2s^2 2p^2 {}^3P_0 - 2s^2 2p^2 {}^3P_1 } right) . A comparison of these with observational data for the 1973 December 17 solar flare, obtained by the Naval Research Laboratory's S082A and S082B spectrographs on board Skylab, reveals reasonably good agreement between theory and observation for R 1[= I(242.07 mathop ? limits^c)/I(1354.08 Å)], which provides some support for the accuracy of the atomic data adopted in the line ratio calculations. However, our results for R 2 indicate that the emission feature in flare spectra at 338.06 Å, previously identified as the Fe xxi 2s 22p 2 3 p 1 - 2s 22p 2 1 S line, is not due to this species but may be the Ca v 3p 4 3 p 1 - 3p 33d 3 P 2 transition. The potential of using R 1 as an electron temperature diagnostic for the Fe xxi line emitting regions of cool star coronae, through a combination of Extreme Ultraviolet Explorer and Hubble Space Telescope observations, is briefly discussed.

Keenan, F. P.; Foster, V. J.; Aggarwal, K. M.; Widing, K. G.

1996-11-01

44

Polycyclic aromatic hydrocarbons (PAHs) in wetland soils under different land uses in a coastal estuary: toxic levels, sources and relationships with soil organic matter and water-stable aggregates.  

PubMed

The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) were determined in the soils from industrial, wharf, cropland, milldam and natural wetland sites to characterize their distributions, toxic levels and possible sources in the Pearl River Estuary and identify their relationships with soil organic matter (SOM) and water-stable aggregates (WSAs). Our results indicate that the average concentration of total PAHs in this region reached a moderate pollution level, which was higher than that in other larger estuaries in Asia. The average level of total PAHs in industrial soils was 1.2, 1.5, 1.6 and 2.3 times higher than those in soils from wharf, cropland, milldam and natural wetland sites, respectively. Greater accumulation of PAHs occurred in the middle and/or bottom soil layers where 3-ring PAHs were dominant. Industrial soils also exhibited the highest toxic levels with the highest toxic equivalent concentrations of PAHs, followed by wharf and milldam soils, and the cropland and wetland soils had the lowest toxicity. The diagnostic ratios suggested that PAHs primarily originated from biomass and coal combustion at industrial and milldam sites, and petroleum combustion was determined to be the primary source of PAHs at the wharf, cropland and wetland sites. Both 3-ring and 4-ring PAHs in the milldam and wharf soils were significantly positively correlated with the SOM, whereas the 4,5,6-ring PAHs and total PAHs in industrial soils and the 2-ring PAHs in cropland soils were significantly negatively correlated with the SOM. In addition, large WSAs also exhibited a significant positive correlation with PAHs. PMID:24880593

Xiao, Rong; Bai, Junhong; Wang, Junjing; Lu, Qiongqiong; Zhao, Qingqing; Cui, Baoshan; Liu, Xinhui

2014-09-01

45

Spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) in surface water from Liaohe River Basin, northeast China.  

PubMed

Liaohe River Basin is an important region in northeast China, which consists of several main rivers including Liao River, Taizi river, Daliao River, and Hun River. As a highly industrialized region, the basin receives dense waste discharges, causing severe environmental problems. In this study, the spatial and temporal distribution of aqueous polycyclic aromatic hydrocarbons (PAHs) in Liaohe River Basin from 50 sampling sites in both dry (May) and level (October) periods in 2012 was investigated. Sixteen USEPA priority PAHs were quantified by gas chromatography/mass selective detector. The total PAH concentration ranged from 111.8 to 2,931.6 ng/L in the dry period and from 94.8 to 2766.0 ng/L in the level period, respectively. As for the spatial distribution, the mean concentration of PAHs followed the order of Taizi River > Daliao River > Hun River > Liao River, showing higher concentrations close to large cities with dense industries. The composition and possible sources of PAHs in the water samples were also determined. The fractions of low molecular weight PAHs ranged from 58.2 to 93.3 %, indicating the influence of low or moderate temperature combustion process. Diagnostic ratios, principal component analysis, and hierarchical cluster analysis were used to study the possible source categories in the study area, and consistent results were obtained from different techniques, that PAHs in water samples mainly originated from complex sources, i.e., both pyrogenic and petrogenic sources. The benzo[a]pyrene equivalents (EBaP) characterizing the ecological risk of PAHs to the aquatic environment suggested that PAHs in Liaohe River Basin had already caused environmental health risks. PMID:24554296

Lv, Jiapei; Xu, Jian; Guo, Changsheng; Zhang, Yuan; Bai, Yangwei; Meng, Wei

2014-06-01

46

Backscatter factors and mass energy-absorption coefficient ratios for diagnostic radiology dosimetry  

NASA Astrophysics Data System (ADS)

Backscatter factors, B, and mass energy-absorption coefficient ratios, (?en/?)w, air, for the determination of the surface dose in diagnostic radiology were calculated using Monte Carlo simulations. The main purpose was to extend the range of available data to qualities used in modern x-ray techniques, particularly for interventional radiology. A comprehensive database for mono-energetic photons between 4 and 150 keV and different field sizes was created for a 15 cm thick water phantom. Backscattered spectra were calculated with the PENELOPE Monte Carlo system, scoring track-length fluence differential in energy with negligible statistical uncertainty; using the Monte Carlo computed spectra, B factors and (?en/?)w, air were then calculated numerically for each energy. Weighted averaging procedures were subsequently used to convolve incident clinical spectra with mono-energetic data. The method was benchmarked against full Monte Carlo calculations of incident clinical spectra obtaining differences within 0.3-0.6%. The technique used enables the calculation of B and (?en/?)w, air for any incident spectrum without further time-consuming Monte Carlo simulations. The adequacy of the extended dosimetry data to a broader range of clinical qualities than those currently available, while keeping consistency with existing data, was confirmed through detailed comparisons. Mono-energetic and spectra-averaged values were compared with published data, including those in ICRU Report 74 and IAEA TRS-457, finding average differences of 0.6%. Results are provided in comprehensive tables appropriated for clinical use. Additional qualities can easily be calculated using a designed GUI interface in conjunction with software to generate incident photon spectra.

Benmakhlouf, Hamza; Bouchard, Hugo; Fransson, Annette; Andreo, Pedro

2011-11-01

47

Backscatter factors and mass energy-absorption coefficient ratios for diagnostic radiology dosimetry.  

PubMed

Backscatter factors, B, and mass energy-absorption coefficient ratios, (?(en)/?)(w, air), for the determination of the surface dose in diagnostic radiology were calculated using Monte Carlo simulations. The main purpose was to extend the range of available data to qualities used in modern x-ray techniques, particularly for interventional radiology. A comprehensive database for mono-energetic photons between 4 and 150 keV and different field sizes was created for a 15 cm thick water phantom. Backscattered spectra were calculated with the PENELOPE Monte Carlo system, scoring track-length fluence differential in energy with negligible statistical uncertainty; using the Monte Carlo computed spectra, B factors and (?(en)/?)(w, air) were then calculated numerically for each energy. Weighted averaging procedures were subsequently used to convolve incident clinical spectra with mono-energetic data. The method was benchmarked against full Monte Carlo calculations of incident clinical spectra obtaining differences within 0.3-0.6%. The technique used enables the calculation of B and (?(en)/?)(w, air) for any incident spectrum without further time-consuming Monte Carlo simulations. The adequacy of the extended dosimetry data to a broader range of clinical qualities than those currently available, while keeping consistency with existing data, was confirmed through detailed comparisons. Mono-energetic and spectra-averaged values were compared with published data, including those in ICRU Report 74 and IAEA TRS-457, finding average differences of 0.6%. Results are provided in comprehensive tables appropriated for clinical use. Additional qualities can easily be calculated using a designed GUI interface in conjunction with software to generate incident photon spectra. PMID:22024474

Benmakhlouf, Hamza; Bouchard, Hugo; Fransson, Annette; Andreo, Pedro

2011-11-21

48

Toxicity evaluation and source apportionment of Polycyclic Aromatic Hydrocarbons (PAHs) at three stations in Istanbul, Turkey.  

PubMed

This paper focuses on the toxicity evaluation and source apportionment of Polycyclic Aromatic Hydrocarbons (PAHs) in three monitoring stations in Istanbul, Turkey. A total of 326 airborne samples were collected and analyzed for 16 PAHs and Total Suspended Particles (TSP) for the period of September 2006-December 2007. The total average PAH concentrations were 100.7±61.3, 84.6±46.7 and 25.1±13.3ngm(-3) and the TSP concentrations were 101.2±53.2, 152.3±99.1, 49.8±18.6?gm(-3) for URB1, URB2 and RUR stations, respectively. Benzo(a)Pyren (BaP) toxic equivalency factors to PAH concentration values were calculated indicating that the health risk of BaP and DiBenz(a,h)Anthracene (markers of traffic emissions) have the highest contribution compared to all of the other species measured at the sampling sites. In order to determine PAH sources, two different source apportionment techniques were applied to the measurements; diagnostic ratios (DR) and Positive Matrix Factorization (PMF). The results of the two applications were compatible indicating the vehicle emissions - especially diesel engines - as the major source for urban stations. PMID:24342492

Hanedar, Asude; Alp, Kadir; Kaynak, Burçak; Av?ar, Edip

2014-08-01

49

SPITZER IRS SPECTRAL MAPPING OF THE TOOMRE SEQUENCE: SPATIAL VARIATIONS OF PAH, GAS, AND DUST PROPERTIES IN NEARBY MAJOR MERGERS  

SciTech Connect

We have mapped the key mid-IR diagnostics in eight major merger systems of the Toomre sequence (NGC 4676, NGC 7592, NGC 6621, NGC 2623, NGC 6240, NGC 520, NGC 3921, and NGC 7252) using the Spitzer Infrared Spectrograph. With these maps, we explore the variation of the ionized-gas, polycyclic aromatic hydrocarbon (PAH), and warm gas (H{sub 2}) properties across the sequence and within the galaxies. While the global PAH interband strength and ionized gas flux ratios ([Ne III]/[Ne II]) are similar to those of normal star-forming galaxies, the distribution of the spatially resolved PAH and fine structure line flux ratios is significantly different from one system to the other. Rather than a constant H{sub 2}/PAH flux ratio, we find that the relation between the H{sub 2} and PAH fluxes is characterized by a power law with a roughly constant exponent (0.61 {+-} 0.05) over all merger components and spatial scales. While following the same power law on local scales, three galaxies have a factor of 10 larger integrated (i.e., global) H{sub 2}/PAH flux ratio than the rest of the sample, even larger than what it is in most nearby active galactic nuclei. These findings suggest a common dominant excitation mechanism for H{sub 2} emission over a large range of global H{sub 2}/PAH flux ratios in major mergers. Early-merger systems show a different distribution between the cold (CO J = 1-0) and warm (H{sub 2}) molecular gas components, which is likely due to the merger interaction. Strong evidence for buried star formation in the overlap region of the merging galaxies is found in two merger systems (NGC 6621 and NGC 7592) as seen in the PAH, [Ne II], [Ne III], and warm gas line emission, but with no apparent corresponding CO (J = 1-0) emission. The minimum of the 11.3/7.7 {mu}m PAH interband strength ratio is typically located in the nuclei of galaxies, while the [Ne III/[Ne II] ratio increases with distance from the nucleus. Our findings also demonstrate that the variations of the physical conditions within a merger are much larger than any systematic trends along the Toomre sequence.

Haan, S.; Armus, L.; Laine, S.; Surace, J. A.; Diaz-Santos, T.; Beirao, P.; Stierwalt, S. [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Charmandaris, V. [Department of Physics and Institute of Theoretical and Computational Physics, University of Crete, GR-71003 Heraklion (Greece); Smith, J. D. [Ritter Astrophysical Observatory, University of Toledo, Toledo, OH 43606 (United States); Schweizer, F.; Murphy, E. J. [Observatories of the Carnegie Institution, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Brandl, B. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Evans, A. S.; Hibbard, J. E. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Yun, M. [Astronomy Department, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003 (United States); Jarrett, T. H. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)

2011-12-01

50

Time trends in the levels and patterns of polycyclic aromatic hydrocarbons (PAHs) in pine bark, litter, and soil after a forest fire.  

PubMed

Forest fires are known as an important natural source of polycyclic aromatic hydrocarbons (PAHs), but time trends of PAH levels and patterns in various environmental compartments after forest fires have not been thoroughly studied yet. In this study, 16 US-EPA priority PAHs were analyzed for pine bark, litter, and soil samples collected one, three, five, and seven months after a forest fire in Pohang, South Korea. At the first sampling event, the highest levels of ?16 PAHs were measured for the three types of samples (pine bark: 5,920 ng/g, litter: 1,540 ng/g, and soil: 133 ng/g). Thereafter, there were apparent decreasing trends in PAH levels; the control samples showed the lowest levels (pine bark: 124 ng/g, litter: 75 ng/g, and soil: 26 ng/g). The levels of PAHs in the litter and soil samples normalized by organic carbon (OC) fractions also showed decreasing trends, indicating a direct influence of the forest fire. Among the 16 target PAHs, naphthalene was a dominant compound for all types of samples. Light PAHs with 2-4 rings significantly contributed to the total concentration, and their contribution decreased in the course of time. Runoff by heavy precipitation, evaporation, and degradation of PAHs in the summer were probably the main reasons for the observed time trends. The results of principal component analysis (PCA) and diagnostic ratio also supported that the forest fire was indeed an important source of PAHs in the study area. PMID:23972323

Choi, Sung-Deuk

2014-02-01

51

Diurnal and nocturnal variations of PAHs in the Lhasa atmosphere, Tibetan Plateau: Implication for local sources and the impact of atmospheric degradation processing  

NASA Astrophysics Data System (ADS)

Due to the unique characteristics, such as intensive radiation, high altitude and low humidity, plateau climate importantly affects the airborne organic contaminants' behavior in the environment. In this study, USEPA priority polycyclic aromatic hydrocarbons (PAHs) and benzo[e]pyrene were detected in the air samples collected at two suburban sites in Lhasa city. The total concentrations of USEPA priority fifteen PAHs (except naphthalene) in the particulate phase ranged from 4.4 to 60 ng/m3, while in the gas phase from 79 to 350 ng/m3. Integrated results of the multiple diagnostic ratios indicated that the major potential sources of PAHs in Lhasa city were local incomplete combustion of wood and cow dung cake. Particulate and gaseous PAH levels in this study displayed two clear and different diurnal and nocturnal concentration patterns, however, no distinct diurnal and nocturnal variation was observed for the total suspended particles (TSP) concentrations. No significant correlation was found between TSP concentrations and particle-bound PAHs, meaning physicochemical processes play an important role in diurnal and nocturnal variations of PAHs in the atmosphere except emission sources in this study. Based on the diurnal and nocturnal changes of the percentage of particulate phase PAHs in total PAHs, it suggested that gas-particle partitioning driven by temperature makes a great contribution to the variations of PAHs concentrations. The most susceptible to transformation between gas and particle phase chemicals are PHE, ANT, FLA, PYR, BaA and CHR. In addition, our observation suggested that atmospheric reaction and photolytic degradation also exert an important impact on the variations of PAHs in both phases in the atmosphere of Lhasa city.

Liu, Junwen; Li, Jun; Lin, Tian; Liu, Di; Xu, Yue; Chaemfa, Chakra; Qi, Shihua; Liu, Fobang; Zhang, Gan

2013-04-01

52

Laboratory Studies of Interstellar PAH Analogs  

NASA Technical Reports Server (NTRS)

Polycyclic aromatic hydrocarbons (PAHs) are now considered to be an important and ubiquitous component of the organic material in space. PAHs are found in a large variety of extraterrestrial materials such as interplanetary dust particles (IDPs) and meteoritic materials. PAHs are also good candidates to account for the infrared emission bands (UIRs) and the diffuse interstellar optical absorption bands (DIBs) detected in various regions of the interstellar medium. The recent observations made with the Infrared Space Observatory (ISO) have confirmed the ubiquitous nature of the UIR bands and their carriers. PAHs are though to form through chemical reactions in the outflow from carbon-rich stars in a process similar to soot formation. Once injected in the interstellar medium, PAHs are further processed by the interstellar radiation field, interstellar shocks and energetic particles. A major, dedicated, laboratory effort has been undertaken over the past years to measure the physical and chemical characteristics of these complex molecules and their ions under experimental conditions that mimic the interstellar conditions. These measurements require collision-free conditions where the molecules and ions are cold and chemically isolated. The spectroscopy of PAHs under controlled conditions represents an essential diagnostic tool to study the evolution of extraterrestrial PAHs. The Astrochemistry Laboratory program will be discussed through its multiple aspects: objectives, approach and techniques adopted, adaptability to the nature of the problem(s), results and implications for astronomy as well as for molecular spectroscopy. A review of the data generated through laboratory simulations of space environments and the role these data have played in our current understanding of the properties of interstellar PAHs will be presented. The discussion will also introduce the newest generation of laboratory experiments that are currently being developed in order to provide a closer simulation of space environments and a better support to space missions.

Salama, Farid; DeVincenzi, Donald (Technical Monitor)

2000-01-01

53

Molecular Spectroscopy in Astrophysics: Interstellar PAHs  

NASA Technical Reports Server (NTRS)

Polycyclic aromatic hydrocarbons (PAHs) are now considered to be an important and ubiquitous component of the organic material in space. PAHs are found in a large variety of extraterrestrial materials such as interplanetary dust particles (IDPs) and meteoritic materials. PAHs are also good candidates to account for the infrared emission bands (UIRs) and the diffuse interstellar optical absorption bands (DIBs) detected in various regions of the interstellar medium. The recent observations made with the Infrared Space Observatory (ISO) have confirmed the ubiquitous nature of the UIR bands and their carriers. PAHs are thought to form through chemical reactions in the outflow from carbon-rich stars in a process similar to soot formation. Once injected in the interstellar medium, PAHs are further processed by the interstellar radiation field, interstellar shocks and energetic particles. A long-term laboratory effort has been undertaken to measure the physical and chemical characteristics of these carbon molecules and their ions under experimental conditions that mimic the interstellar conditions. These measurements require collision-free conditions where the molecules and ions are cold and chemically isolated. The spectroscopy of PAHs under controlled conditions represents an essential diagnostic tool to study the evolution of extraterrestrial PAHs. The laboratory results will be discussed as well as the implications for astronomy and for molecular spectroscopy. A review of the data generated through laboratory simulations of space environments and the role these data have played in our current understanding of the properties of interstellar PAHs will be presented. We will also present the new generation of laboratory experiments that are currently being developed in order to provide a closer simulation of space environments and a better support to space missions.

Salama, Farid; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

54

Responses of bioaugmented ryegrass to PAH soil contamination.  

PubMed

The physiological and biochemical responses of ryegrass (Lolium multiflorum) to PAH induced stress in soils contaminated with phenanthrene and pyene were investigated, in the presence of PAH-degrading bacteria (Acinetobacteria junii) or arbuscular mycorrhizal fungi (AM fungi, Glomus mossae). The parameters monitored included chlorophyll content, chlorophyll a/b ratio, soluble-carbohydrate content, soluble-protein, malondialdehyde and electrolyte leakage, and superoxide dismutase (SOD) and peroxidase (POD) activities. Ryegrass showed good resistance and acclimation to PAH stress in soil, however, PAH contamination resulted in adverse effects such as damage of photosynthetic function and acceleration of shoot senescence. At PAH level of 100 mg kg(-1), chlorophyll contents were 14% lower than control (no PAH). Activities of SOD and POD were more sensitive indicators of PAH stress as compared to other parameters. However, all parameters showed trends based on either the bioaugmentation of the plants or PAH treatment level. It was concluded that the inoculation of AMF and PAH-degrading bacteria, especially the former, have a positive effect on alleviation of PAH toxicity to ryegrass plants. Furthermore, the inoculation of AMF increased the shoot and biomass of ryegrass by 11-19% and 18-78%, respectively. Bioaugmented ryegrass plants show promise as a host plants in the phytoremediation of PAH contaminated soils. PMID:21598775

Li, J H; Yu, X Z; Wu, S C; Wang, X R; Wang, S H; Tam, N F Y; Wong, M H

2011-01-01

55

A diagnostic marker for childhood apraxia of speech: the lexical stress ratio  

Microsoft Academic Search

This report includes an extended review of the contemporary inclusionary criteria used to identify children with suspected apraxia of speech (sAOS) and describes findings supporting a lexical stress marker for sAOS. The thesis is that although a deficit in speech praxis is the core disorder in sAOS, only a few diagnostic markers for sAOS assess this speech motor control construct.

Lawrence D. Shriberg; Thomas F. Campbell; Heather B. Karlsson; Roger L. Brown; Jane L. Mcsweeny; Connie J. Nadler

2003-01-01

56

Aryl hydrocarbon receptor mediated activities in road dust from a metropolitan area, Hanoi-Vietnam: Contribution of polycyclic aromatic hydrocarbons (PAHs) and human risk assessment.  

PubMed

Dioxin-Responsive Chemical-Activated LUciferase gene eXpression assay (DR-CALUX) was applied to assess the total toxic activity of the mixture of PAHs and related compounds as well as dioxin-related compounds in road dust from urban areas of Hanoi, Vietnam. Road dust from Hanoi contained significantly higher DR-CALUX activities (3 to 39, mean 20ng CALUX-TEQ/g dw) than those from a rural site (2 to 13, mean 5ng CALUX-TEQ/g dw). The total concentrations of 24 major PAHs (?24PAHs) in urban road dust (0.1 to 5.5, mean 2.5?g/g dw) were also 6 times higher than those in rural road dust (0.08 to 1.5, mean 0.4?g/g dw). Diagnostic ratios of PAHs indicated vehicular engine combustion as the major PAH emission source in both sites. PAHs accounted for 0.8 to 60% (mean 10%) and 2 to 76% (mean 20%) of the measured CALUX-TEQs in road dust for Hanoi the rural site, respectively. Benzo[b]-/benzo[k]fluoranthenes were the major TEQ contributors among PAHs, whereas DRCs contributed <0.1% to CALUX-TEQs for both rural and urban sites. These results suggest TEQ contribution of other aryl hydrocarbon receptor agonists in road dust. Significant PAH concentrations in urban dust indicated high mutagenic and carcinogenic potencies. Estimated results of incremental life time cancer risk (ILCR) indicated that Vietnamese populations, especially those in urban areas such as Hanoi, are potentially exposed to high cancer risk via both dust ingestion and dermal contact. This is the first study on the exposure risk of AhR agonists, including PAHs and DRCs, in urban road dust from a developing country using a combined bio-chemical analytical approach. PMID:24522011

Tuyen, Le Huu; Tue, Nguyen Minh; Suzuki, Go; Misaki, Kentaro; Viet, Pham Hung; Takahashi, Shin; Tanabe, Shinsuke

2014-09-01

57

PAH-profiles in sediment cores from the Baltic Sea.  

PubMed

To document the historical input the PAH-profiles of sediment cores in two different basins of the Baltic Sea, the Gotland Basin (GB) and Arkona Basin (AB), were analysed by means of GC-MS. 35 PAHs were quantified in all samples, and additionally, several marker PAHs, like Cyclopenta[cd]phenanthrene (CCP) for combustion processes and retene for terrigenous input, were quantified in selected samples. The preindustrial sediments (older than 200-250 years) in the GB core illustrate concentrations <100 ng PAH15 g(-1) d.w. Calculated PAH-ratios indicated combustion processes as the main sources for both basins. The Perylene concentrations within the sediment cores decrease with increasing depth, along with an increase in relative percentage, indicating slow diagenetic processes. The preservation and enrichment of the introduced PAHs was more pronounced in the GB core. PMID:12146840

Ricking, M; Schulz, H M

2002-06-01

58

Concentrations, sources and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in soils of Liaohe estuarine wetland.  

PubMed

Concentration, source, and risk of PAHs were investigated in 31 sites from surface soils of Liaohe estuarine wetland. Total PAHs concentrations ranged from 293.4 to 1735.9 ng/g with a mean of 675.4 ng/g. The 3- and 4-ring PAHs were the dominant species. The ratios of high-molecular weight PAHs to low-molecular weight PAHs and anthracene/(anthracene+phenanthrene) were calculated to apportion sources of PAHs. It was found that both pyrogenic and petrogenic PAHs sources were important. Effect range low and effect range median showed that the PAHs would occasionally cause adverse effects. The nemerow composite index revealed that about 41.9% soil sampling sites were safety; about 58.1% sites had different grades of PAHs pollution. PMID:21681396

Wang, Nannan; Lang, Yinhai; Cheng, Fangfang; Wang, Minjie

2011-10-01

59

PAH Emission in the Giant H II Region RCW49  

NASA Astrophysics Data System (ADS)

We use the giant H II region RCW49 as an astrophysical laboratory to improve our understanding of PAH emission and PAH emission models. If the broad emission features seen in the near and mid infrared are due to PAHs, then specific band ratios and band widths are predicted to change with local conditions. We use the high spatial resolution of Spitzer along with high sensitivity to create a series of IRS maps to test these models. In addition, we examine the variation in the PAH/continuum ratio to probe the small grain abundances. Since the entire region has been mapped by IRAC we will also directly measure the contribution by PAH and continuum emission to the IRAC [5.8] and IRAC [8.0] bands and we will predict the line emission in all IRAC bands from the longer wavelength line emission measured by the Spitzer IRS high resolution mode.

Wolfire, Mark; Indebetouw, Remy; Mathis, John; Whitney, Barbara

2005-06-01

60

Laboratory Study of the Diagnostic Utility of the 3C/3D Line Ratio in Fe XVII  

SciTech Connect

Fe XVII x-ray emission is present, in a multitude of sources, such as the corona of the Sun, Capella, and Procyon. Two of the strongest lines observed in these spectra are the resonance and intercombination lines located at 15.01 and 15.26 {angstrom}, respectively. As part, of the laboratory astrophysics program at the electron beam ion traps EBIT-I and EBIT-II located at the Lawrence Livermore National Laboratory we have measured this line ratio for the case where the relative abundance of Fe XVI to Fe XVII is {approx} 1. Our results show that an Fe XVI innershell satellite line coincides with the intercombination line and can significantly reduce the relative intensity, R, of the resonance to intercombination line. The fact that the apparent, relative intensity of the resonance and intercombination line in Fe XVII is sensitive to the strength of an Fe XVI innershell satellite, and therefore, the relative abundance of Fe XVI to Fe XVII, makes the line ratio a diagnostic of temperature, and explains the anomalously low ratios observed in the solar and stellar coronae.

Beiersdorfer, P; Chen, H; Chen, M H; Reed, K J; Brown, G V

2002-06-18

61

Occurrence and source apportionment of PAHs in highly vulnerable karst system.  

PubMed

The concentration and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) in topsoil, groundwater and groundwater suspended solids (SS) at Guozhuang karst water system of northern China were investigated. The total concentration of PAHs ranged from 622 to 87,880ng/g dry weight in topsoil, from 4739 to 59,314ng/g dry weight in SS, and from 2137 to 9037ng/L in groundwater, with mean values of 17,174ng/g, 11,990ng/g and 5020ng/L, respectively. High concentrations of PAHs were mainly observed in the coal mining industrial area and the discharge area. The composition of PAHs indicated that low molecular weight PAHs were predominant in groundwater samples, the content of medium molecular weight PAHs was elevated in SS, and carcinogenic high molecular weight PAHs were frequently detected in topsoil. The high contents of low-medium molecular weight PAHs in groundwater and SS suggested relatively recent local sources of PAHs that were transported into the aquifer via leakage of contaminated surface water and/or infiltration of PAH-containing precipitation. The results of evaluating sources of PAHs using ratios of specific PAH compounds showed that PAHs mainly originated from coal and wood combustion. Furthermore, five sources were identified by positive matrix factorization (PMF) model, and the contribution to the total loadings of groundwater PAHs were: 2% for unburnt oil, 32% for coal combustion, 22% for vehicle emission, 27% for biomass combustion and 18% for coke production, respectively. Furthermore, strong correlations of total PAHs with total organic carbon (TOC) in topsoil indicated co-emission of PAHs and TOC. Poor correlations of PAHs with dissolved organic carbon (DOC) in groundwater indicated that other factors exert stronger influences. Therefore, PAHs might have posed a major threat to the quality of potable groundwater in Guozhuang karst water system. PMID:24852613

Shao, Yixian; Wang, Yanxin; Xu, Xiaoqing; Wu, Xiao; Jiang, Zhou; He, Shanshan; Qian, Kun

2014-08-15

62

[Contamination characteristics of polycyclic aromatic hydrocarbons (PAHs) in surface water from Jialing River in Chongqing].  

PubMed

To understand the composition, sources and contamination characteristics of PAHs in surface water from Jialing River in Chongqing, water samples were collected from 8 different sections in August 2009 and the concentrations of the 16 priority PAHs were determined using GC-MS. The results indicated that the concentration of Sigma PAHs (the total PAHs) in the water body ranged from 467.13 to 987.97 ng x L(-1), with an average concentration of 702.91 ng x L(-1). PAHs concentrations in surface waters were positively correlated with the dissolved organic carbon content. The predominant PAHs in the water body were 2-3 ring PAHs, accounting for 68.90% of Sigma PAHs. The ratios of specific PAHs revealed that the main PAHs source in Cuntan was the combustion of wood and coal, the origin of PAHs in Caotianmen was mostly petrogenic; whereas the main PAHs source in other sampling sections of Jialing River in Chongqing was petroleum combustion. Compared with other areas in China, the PAHs contamination in Jialing River around Chongqing was at a relatively low level, however, the concentrations of BaP in the surface water of 5 sampling sites exceeded the environmental quality standards for surface water in China. PMID:23002611

Cai, Wen-Liang; Luo, Gu-Yuan; Xu, Xiao-Yi; Du, Xian

2012-07-01

63

The UV to Near-IR Optical Properties of PAHs: A Semi-Empirical Model  

NASA Technical Reports Server (NTRS)

Interstellar Polycyclic Aromatic Hydrocarbon (PAH) infrared emission features represent an important and unique diagnostic tool of the chemical and physical conditions throughout the universe. However, one challenge facing the widely accepted PAH emission model has been the detection of infrared features in regions of low UV flux. Utilizing recently published laboratory Near Infrared VIR) PAH ion absorption data measured in our laboratory, we build upon previous models for PAH ion absorption in the UV-Vis to extrapolate a new model which incorporates PAH ion absorption in the NIR. This model provides a basis for comparing the relative energy absorption of PAH ions in the UV-Vis and NIR regions for a wide variety of stellar types. This model demonstrates that the radiation from late-type stars can pump the mid-IR PAH features.

Mattioda, A. L.; Allamandola, L. J.; Hudgins, D. M.

2005-01-01

64

A systematic review and meta-analysis of the diagnostic accuracy of the spot urinary protein creatinine ratio (PCR) and the spot urinary albumin creatinine ratio (ACR) in the management of suspected pre-eclampsia  

Microsoft Academic Search

ObjectiveTo determine the diagnostic accuracy of the albumin creatinine ratio (ACR) and protein creatinine ratio (PCR) compared to the 24 h total urine (24 h TU) and how well they predict adverse outcomes for mother and baby in women with suspected pre-eclampsia (PE).MethodsSystematic searches in electronic databases, reference lists and contact with experts. All studies reporting on ACR and\\/or PCR

R K Morris; M Doug; M D Kilby

2011-01-01

65

Sources of PCDD/Fs, non-ortho PCBs and PAHs in sediments of high and low impacted transboundary rivers (Belgium-France).  

PubMed

PAHs, PCDD/Fs and non-ortho PCBs have been assessed in Yser and Upper-Scheldt river sediments. Higher contamination levels were observed in the Upper-Scheldt sediments: maximum concentrations for the 16 US-EPA PAHs, PCDD/Fs and non-ortho PCBs respectively amount to 8.9 mg kg(-1), 12 ng TEQ kg(-1) and 5.1 ng TEQ kg(-1). Diagnostic PAH ratios in sediments and atmospheric samples suggest that the PAH compounds are from pyrolytic origin, more specifically combustion processes. The huge consumption of coal in cokes-ovens and smelters and its use for house-heating in Northern France, although decreasing during the last decades, are in support of that suggestion. PCDD/F fingerprints in sediments and deposition material indicate that OCDD is the dominant congener. In addition use of pentachlorophenol (PCP) in the past led to a minor contribution of PCDD/Fs in our sediment samples. Non-ortho PCBs form a substantial fraction of the total TEQ concentrations observed in the sediments. Since the 1980s and 1990s a substantial reduction of the PCDD/F sediment concentrations is observed, but this is not the case for the PAHs. PMID:21741672

Sanctorum, Hermes; Elskens, Marc; Leermakers, Martine; Gao, Yue; Charriau, Adeline; Billon, Gabriel; Goscinny, Séverine; De Cooman, Ward; Baeyens, Willy

2011-09-01

66

PAH concentrations in the moss species Hylocomium splendens (Hedw.) B.S.G. and Pleurozium schreberi (Brid.) Mitt. from the Kielce area (south-central Poland).  

PubMed

Forty eight samples of mosses Hylocomium splendens and Pleurozium schreberi from the Kielce area (south-central Poland) were analyzed for seventeen polycyclic aromatic hydrocarbons. The PAH concentrations varied from 558.00 ?g/kg (ppb) to 4457.00 ?g/kg in H. splendens and from 643.00 to 3086.00 ?g/kg in P. schreberi. In both moss species phenanthrene (75.00-732.00 ?g/kg), fluoranthene (101.00-577.00 ?g/kg) and pyrene (68.00-568.00 ?g/kg) predominated, but H. splendens accumulated more PAHs than P. schreberi at eighteen different sites. The highest PAH concentrations were noted at sites located close to the housing estates (sites 1-10) and potential emission sources (e.g. heat and power generating plant "Kielce S.A.") (sites 19-21). The moss samples displayed the diverse ring sequence, but the most prevalent was four>five>three>six. The diagnostic ratios (three+four ring/total PAHs, Flu/Py, Phen/Ant, Phen/Phen+Ant, Flu/Flu+Py, IndPy/IndPy+BghiPe and BaA/BaA+Chr) indicated that coal and petroleum combustion was a principal PAH source in the study area. PMID:21652075

Do??gowska, Sabina; Migaszewski, Zdzis?aw M

2011-09-01

67

Cancer risk evaluation of brick kiln workers exposed to dust bound PAHs in Punjab province (Pakistan).  

PubMed

Principal objective of this study was to evaluate the health risks of brick kiln workers to dust bound PAHs exposure in Punjab province (Pakistan). To this aim, surface dust samples were collected from brick kiln units located in Chung Khurd (Lahore city), Gujranwala city and Sohra village (in the vicinity of Gujranwala). The highest ?PAH levels were measured in the dust samples collected in Sohdra village (mean 2578ngg(-1) d.w., range 302-6757ngg(-1) d.w.) followed by Gujranwala city (mean 957, range 16.1-1963ngg(-1) d.w.) and Chung Khurd (mean 882, range 692-1007ngg(-1) d.w.). Source identification using diagnostic ratios and principal component analysis identified coal and wood combustion as the major PAHs sources. The cancer risk model (CR-Model 1) and the Incremental Lifetime Cancer Risk model (ILCR-Model 2) were used to evaluate the cancer risk assessment via ingestion, inhalation and dermal contact pathways. Both models suggested that brick kiln workers (including adults and children) were exposed to high-potential carcinogenic risk via both ingestion and dermal contact pathways during the brick making process. This study also emphasizes the need for pollution control in the brick kiln industry of Pakistan. PMID:24973936

Kamal, Atif; Malik, Riffat Naseem; Martellini, Tania; Cincinelli, Alessandra

2014-09-15

68

Biodegradation and adsorption of C1- and C2-phenanthrenes and C1- and C2-dibenzothiophenes in the presence of clay minerals: effect on forensic diagnostic ratios.  

PubMed

The impact of modified montmorillonites on adsorption and biodegradation of crude oil C1-phenanthrenes, C1-dibenzothiophenes, C2-phenanthrenes and C2-dibenzothiophenes was investigated in aqueous clay/oil microcosm experiments with a hydrocarbon degrading microorganism community. Consequently, the effect on C1-dibenzothiophenes/C1-phenanthrenes, C2-dibenzothiophenes/C2-phenanthrenes, 2+3-methyldibenzothiophene/4-methyldibenzothiophene and 1-methyldibenzothiophene/4-methyldibenzothiophene ratios commonly used as diagnostic ratios for oil forensic studies was evaluated. The clay mineral samples were treated to produce acid activated montmorillonite, organomontmorillonite and homoionic montmorillonite which were used in this study. The different clay minerals (modified and unmodified) showed varied degrees of biodegradation and adsorption of the C1-phenanthrenes, C1-dibenzothiophenes, C2-phenanthrenes and C2-dibenzothiophenes. The study indicated that as opposed to biodegradation, adsorption has no effect on the diagnostic ratios. Among the diagnostic ratios reviewed, only C2-dibenzothiophenes/C2-phenanthrenes ratio was neither affected by adsorption nor biodegradation making this ratio very useful in forensic studies of oil spills and oil-oil correlation. PMID:24275986

Ugochukwu, Uzochukwu C; Head, Ian M; Manning, David A C

2014-07-01

69

Distribution and sources of polycyclic aromatic hydrocarbon (PAH) in marine environment of China  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbons (PAHs) are potentially carcinogenic and mutagenic compounds that have raised considerable environmental concern. The highest concentrations of PAHs in the coastal sediment samples in China was 5.8 11.0?g/g (dry weight) in the core from the Huangpu River, Shanghai. The second highest concentration of PAHs was 4.42?g/g (dry weight) in surface sediment of Victoria Harbour in Hong Kong, and 5.73?g/g (dry weight) in sediment of Jiaozhou Bay, Qingdao City. The low concentrations of PAHs were always in the sediments far away from industrial zones and cities, and ranged from 0.10 to 0.30?g/g (dry weight). Several environmental parameters are considered for the identification of sources of PAHs in marine environment. High proportion of naphthalene, low molecular weight PAHs and alkylated PAHs, plus high ratio of phenanthrene to anthracene (>15) and low ratio of fluoranthene to pyrene (<1) suggested a petrogenic source. According to these parameters, the Changjiang (Yangtze) River estuary of Shanghai, Jiaozhou Bay of Qingdao City, Zhujiang (Pearl) River mouth, Jiulong River mouth and most of Hong Kong coastal waters were heavily contaminated by PAHs from petrogenic sources. However, PAHs in rural coastal areas were dominated by pyrolytic origin PAHs. This review clearly showed that oil pollution and incomplete combustion of oil, coal and biomass are the main reason for PAHs anormalies in the study areas.

Zheng, Jinshu; Richardson, Bruce J.; Shouming, O.; Zheng, Jianhua

2004-06-01

70

[Characteristics of Pahs pollution in sediments from Leizhou coastal marine area, Liusha Bay and Shenzhen Bay].  

PubMed

Leizhou coastal marine area, Liusha Bay and Shenzhen Bay represented open coastal area and half-closed bay, respectively. This study discussed the differences of PAHs concentration levels, spatial distribution and sources in sediments from these three marine areas. The results showed that detected ratios of 15 PAHs were 100%, and major compounds were 3-ring and 4-ring PAHs, especialy Phe, Fla, Pry and Bbf; Sigma PAHs concentration was Leizhou < Shenzhen < Liusha. In spatial distribution, PAHs concentrations were the east < the south < the west in Leizhou; the inside > the outside, and the aquaculture > the non-aquaculture in Liusha Bay and Shenzhen Bay. It suggested that large-scale mariculture inside bay played an important role in PAHs pollution and might make it serious. Oil, fossil fuels and biomass burning were the dominant sources of PAHs in sediments from Leizhou coastal area, Liusha Bay and Shenzhen Bay. PMID:22720565

Zhao, Li-Rong; Sun, Sheng-Li; Ke, Sheng

2012-04-01

71

Migration of PAHs in food industry sludge to the air during removal by UV and TiO2.  

PubMed

This study was conducted to investigate the evaporation ratios of polycyclic aromatic hydrocarbons (PAHs) from the food industry treatment sludge. Five PAH compounds having different ring numbers were targeted. The effects of temperature, UV and TiO2 on PAH evaporation were also studied. All applications were performed in a specially designed apparatus. The air in the apparatus was vacuumed to collect the evaporated PAHs on the PUF cartridges. Then, these PUF cartridges were extracted for determination of PAHs. The PAH concentrations were measured by a gas-chromatography mass-spectrometer (GC-MS). 91% of the initial ?5 PAHs in the sludge was evaporated into the air at the end of the UV application. However, this value decreased to 21% when UV was not employed. Initial and final PAH levels in the sludge were measured to determine the removed PAHs which refer to the addition of degraded and evaporated PAHs. The results indicated that the UV-TiO2 application at high temperatures was considered an appropriate PAH removal method because it restricted the evaporation of PAHs while it removed high levels of PAHs. PAHs were mainly removed from the sludge by degradation rather than evaporation with this application. PMID:24726516

Karaca, Gizem; Tasdemir, Yücel

2014-08-01

72

Characteristics of particulate PAHs during a typical haze episode in Guangzhou, China  

NASA Astrophysics Data System (ADS)

The concentrations of polycyclic aromatic hydrocarbons (PAHs) in PM 2.5 and TSP were measured in Guangzhou during a typical haze episode. This episode included NH (non-haze, 3 days), HFN (haze when air masses from north and northeast, 6 days) and HFS (haze when air masses from south, 4 days). The air quality in HFN was much worse than that in NH and HFS. The total average concentrations of PAHs in PM 2.5 were 13.25 ng m -3, 59.82 ng m -3 and 13.09 ng m -3 in NH, HFN and HFS, respectively. It indicated PAH pollution had been substantially aggravated by HFN. PAHs(5 + 6) were the most abundant compounds in HFN and HFS, which accounted for 55-75% of total concentration of PAHs, while PAHs(3 + 4) were the most abundant compounds in NH, which accounted for 54-67% of total concentration of PAHs. TEF (Toxic Equivalency Factors)-adjusted concentrations of 13 particulate PAHs were very high in HFN, indicating high health risks to humans for PAH exposure in HFN. The characteristic ratios of PAHs indicated coal combustion and traffic emission were the major contributors to PAHs in HFN and HFS. The concentrations of particulate PAHs in haze episode were strongly affected by wind speed and wind direction. PAHs in NH could be from long-range transport with high north wind speed, while local emission could be the main contributor of particle-associated PAHs in HFN. The transport speed of air masses was found to play an important role on PAH concentrations.

Tan, Jihua; Guo, Songjun; Ma, Yongliang; Duan, Jingchun; Cheng, Yuan; He, Kebin; Yang, Fumo

2011-10-01

73

Modelling surfactant influenced PAH migration  

Microsoft Academic Search

Within the framework of a comprehensive investigation concerning the use of surfactants to enhance the remediation of PAH contaminations in the subsurface, a multicomponent transport model was developed to study the processes (interactions) taking place when surfactants and PAH migrate through porous media as solutes. Based on a close co-operation with the laboratory investigations during model development only those processes

M. Finkel; R. Liedl; G. Teutsch

1998-01-01

74

Contamination of polycyclic aromatic hydrocarbons (PAHs) in urban soils in Beijing, China.  

PubMed

Soil contamination with polycyclic aromatic hydrocarbons (PAHs) is an increasing problem in many countries, including China. An extensive and systematic survey has been undertaken to evaluate the contamination with PAHs of urban soils in Beijing, China. Soil samples were collected from campuses of universities, schools and kindergartens, public squares, fallow land and roadsides, and were analyzed for 16 PAHs by GC-MS. There was a high variability in the total PAHs (SigmaPAHs) concentrations, ranging from less than 366 to 27,825 ng g(-1). The highest SigmaPAHs concentrations were found at roadsides and industrial sites. Soil organic carbon (SOC) is one of the important factors that can influence the concentrations of PAHs in soils. It was found that concentrations of SigmaPAHs were significantly correlated with that of soil organic carbon. To trace the sources of PAHs, the ratios of phenanthrene to anthracene and fluoranthene to pyrene were used to identify pyrogenic and petrogenic sources, respectively. In most cases, PAHs in soils in urban areas of Beijing were pyrogenic. These sources included motor vehicle exhausts, industrial activities and coal burning. These data can be further used to assess the health risk associated with soils polluted with PAHs. PMID:15992927

Tang, Lily; Tang, Xiang-Yu; Zhu, Yong-Guan; Zheng, Ming-Hui; Miao, Qi-Long

2005-08-01

75

Compound Specific Radiocarbon Analysis (CSRA) Of Polycyclic Aromatic Hydrocarbons(PAHs) in Fine Organic Aerosols From Residential Area Of Suburb Tokyo  

NASA Astrophysics Data System (ADS)

Atmospheric polycyclic aromatic hydrocarbons (PAHs) originate mostly from incomplete combustion of carbon-based fuels. Amongst atmospheric contaminants, PAHs account for most (35-82 percent) of the total mutagenic activity of ambient aerosols. Hence, reduction of air pollution by PAHs is essential for an effective air quality control, which requires reliable source apportionment. Recently developed preparative capillary GC system and microscale 14C analysis made CSRA applicable to environmental samples. The 5730 yr half-life of 14C makes it an ideal tracer for identifying combustion products derived from fossil fuels (14C-free) vs. those from modern biomass (contemporary 14C). In the present study we performed radiocarbon analysis of PAHs in fine particulate aerosols (PM10 and PM1.1) from a residential area in suburb Tokyo, to apportion their origin between fossil and biomass combustion. Acquisition of source information for size segregated aerosols (i.e., PM1.1) from 14C measurement was of special interest as particles with diameter of 1?m or less are known to be able to remain suspended in air for weeks and penetrate into the deepest part of the respiratory system. Total PAHs concentrations (sum of 38 compounds with 3-6 aromatic rings) ranged 0.94-3.25 ng/m3 for PM10 and 0.69-2.68 ng/m3 for PM1.1 samples. Observation of relatively small amount of retene (0.2-0.4 percent of total PAHs) indicates some contribution from wood (Gymnosperm) combustion. Diagnostic isomer pair ratios of PAHs (i.e., 1,7-/2,6-dimethylphenanthrene, fluoranthene/pyrene and indeno [1,2,3-cd]pyrene/benzo[ghi]perylene) indicated mixed contributions both from petroleum and wood/coal combustion sources. Also the ratios implied that the latter source become relatively important in winter than the rest of the year for both PM10 and PM1.1 samples, which coincides with seasonal trend of retene proportion. The source information obtained from 14C analyses will be compared and discussed against that from diagnostic isomer pair ratios.

Kumata, H.; Uchida, M.; Sakuma, E.; Fujiwara, K.; Yoneda, M.; Shibata, Y.

2005-12-01

76

The NASA Ames PAH IR Spectroscopic Database and the far-IR  

NASA Astrophysics Data System (ADS)

Polycyclic Aromatic Hydrocarbons (PAHs) are widespread across the Universe and influence many stages of the Galactic lifecycle. The presence of PAHs has been well established and the rich mid-IR PAH spectrum is now commonly used as a probe into (inter)stellar environments. The NASA Ames PAH IR Spectroscopic Database has been key to test and refine the "PAH hypothesis". This database is a large coherent set (>600 spectra) of laboratory measured and DFT computed infrared spectra of PAHs from C10H8 to C130H28 and has been made available on the web at ( http://www.astrochem.org/pahdb). With a new spectral window opening up; the far-IR, the study of PAH far-IR spectra and the quest for identifying a unique member of the interstellar PAH family has begun. To guide this research, the far-IR (>20 ?m) spectra of different sets of PAHs are investigated using the NASA Ames PAH IR Spectroscopic Database. These sets explore the influence of size, shape, charge and composition on the far-IR PAH spectrum. The far-IR is also the domain of the so-called "drumhead" modes and other molecular vibrations involving low order bending vibrations of the carbon skeleton as a whole. As with drums, these are molecule and shape specific and promise to be a key diagnostic for specific PAHs. Here, the sensitivity of these "drumhead" modes to size and shape is assessed by comparing the frequencies of the lowest drumhead modes of a family of circular shaped (the coronene "family") and rhombus shaped (the pyrene "family") PAH molecules. From this study, some consequences for an observing strategy are drawn.

Boersma, C.; Allamandola, L. J.; Bauschlicher, C. W.; Ricca, A.; Cami, J.; Peeters, E.; Sánchez de Armas, F.; Puerta Saborido, G.; Mattioda, A. L.; Hudgins, D. M.

2011-03-01

77

The Significance of Indirect Deposition on Wintertime PAH Concentrations in an Urban Northern California Creek.  

PubMed

To investigate the main inputs and sources of polycyclic aromatic hydrocarbons (PAHs) into surface water, stream and precipitation samples were collected along an urban tributary to the Sacramento River, California. Dissolved, particulate, and colloid-bound PAHs were monitored four times between October 2004 and March 2005. The total PAH concentrations ranged from 192 to 3784 ng/L in surface water and from 77 to 236 ng/L in precipitation. Naphthalene, phenanthrene, pyrene, and benzo[g,h,i]perylene were the most abundant compounds in both rain and surface water. Surface water had truly dissolved PAH concentrations between 18 and 48 ng/L and precipitation had similar values (15-66 ng/L). PAHs larger than four rings were seldom found in the dissolved phase. Colloid-associated PAHs accounted for 4-25% of the total PAHs in rain, while they contributed only 0.1-6% to the total surface water PAHs. Indirect deposition (i.e., washoff of atmospheric particles previously deposited to land) of PAHs into surface water is likely a more significant input pathway for total PAHs than direct dry or wet deposition during the wet season in California's Mediterranean climate. During the sampling period, there was not an obvious seasonal variation in dissolved PAH concentrations of surface water despite an enormous wintertime increase in the total aqueous concentrations. Particulate matter carried by stormwater runoff was the major source of PAHs in surface water in the early rainy season; this material likely represents a combination of indirect atmospheric inputs and other non-atmospheric anthropogenic inputs (e.g., oil leaks and spills). Selected PAH ratios indicate that observed PAHs in rainwater came from pyrogenic sources and those in surface water had more complicated and variable origins. PMID:20485462

Kim, Daekyun; Young, Thomas M

2009-01-01

78

Significance of Indirect Deposition on Wintertime PAH Concentrations in an Urban Northern California Creek  

PubMed Central

Abstract To investigate the main inputs and sources of polycyclic aromatic hydrocarbons (PAHs) into surface water, stream and precipitation samples were collected along an urban tributary to the Sacramento River, California. Dissolved, particulate, and colloid-bound PAHs were monitored four times between October 2004 and March 2005. The total PAH concentrations ranged from 192 to 3784?ng/L in surface water and from 77 to 236?ng/L in precipitation. Naphthalene, phenanthrene, pyrene, and benzo[g,h,i]perylene were the most abundant compounds in both rain and surface water. Surface water had truly dissolved PAH concentrations between 18 and 48?ng/L and precipitation had similar values (15–66?ng/L). PAHs larger than four rings were seldom found in the dissolved phase. Colloid-associated PAHs accounted for 4–25% of the total PAHs in rain, while they contributed only 0.1–6% to the total surface water PAHs. Indirect deposition (i.e., washoff of atmospheric particles previously deposited to land) of PAHs into surface water is likely a more significant input pathway for total PAHs than direct dry or wet deposition during the wet season in California's Mediterranean climate. During the sampling period, there was not an obvious seasonal variation in dissolved PAH concentrations of surface water despite an enormous wintertime increase in the total aqueous concentrations. Particulate matter carried by stormwater runoff was the major source of PAHs in surface water in the early rainy season; this material likely represents a combination of indirect atmospheric inputs and other non-atmospheric anthropogenic inputs (e.g., oil leaks and spills). Selected PAH ratios indicate that observed PAHs in rainwater came from pyrogenic sources and those in surface water had more complicated and variable origins.

Kim, Daekyun; Young, Thomas M.

2009-01-01

79

Modelling Surfactant Influenced PAH Migration  

NASA Astrophysics Data System (ADS)

Within the framework of a comprehensive investigation concerning the use of surfactants to enhance the remediation of PAH contaminations in the subsurface, a multicomponent transport model was developed to study the processes (interactions) taking place when surfactants and PAH migrate through porous media as solutes. Based on a close co-operation with the laboratory investigations during model development only those processes that could be identified within laboratory experiments have been implemented in the model: (i) surfactant-micellization, (ii) surfactant sorption (formation of hemi- and admicelles), (iii) intra-particle diffusion of PAH, (iv) PAH sorption on hemi- or into admicelles, (v) solution of PAH within micelles. Furthermore, process-oriented descriptions are used to guarantee that only measurable parameters are needed as model input. In a first step column experiments with phenanthrene and the surfactant Terrasurf G50 (Danzer and Grathwohl, 1997, this issue) have been simulated by pure forward modelling in order to validate the conceptual model. Using independently measured parameters only the model is able to reproduce the breakthrough curves of both phenanthrene and Terrasurf G50 very well. Furthermore, the modelling results provide evidence that not only PAH sorption but also the sorption of surfactants may be limited by diffusion. Based upon these results a new conceptual model of the processes involved in the coupled transport of PAH and surfactants has been developed.

Finkel, M.; Liedl, R.; Teutsch, G.

1998-03-01

80

Matrix metalloproteinase-9 and the Cu/Zn ratio as ancillary diagnostic tools in distinguishing between the classical and follicular variants of papillary thyroid carcinoma.  

PubMed

The most common histological variants of papillary thyroid carcinoma (PTC), classical (CPTC) and follicular (FPTC), have different diagnostic features, molecular biology, and prognosis. Matrix metalloproteinase-9 (MMP-9) endopeptidase which degrades the components of the extracellular matrix is essential in the invasive growth and metastasizing of malignant tumors. The serum copper (Cu)/zinc (Zn) ratios are sensitive diagnostic and prognostic indicators in oncology since Cu- and Zn-dependent enzymes play important roles in the genesis and the progression of tumors. The aim of this study was to examine the expressions of MMP-9 in tissues of CPTC and FPTC, as well as to determine the Cu/Zn ratios in the same samples. MMP-9 was determined immunohistochemically, and the concentrations of copper and zinc in thyroid tissue were determined by means of flame atomic absorption spectrometry. The results obtained revealed significantly higher expressions of MMP-9 in CPTC in comparison with FPTC, as well as higher Cu/Zn ratios in CPTC than in FPTC. Thus, determining MMP-9 activities and the Cu/Zn ratios could improve the accuracy of the standard histopathological diagnosis of these two types of PTC. PMID:22528774

Dragutinovi?, Vesna V; Tati?, Svetislav B; Nikoli?-Mandi?, Snežana; Savin, Svetlana; Cveji?, Dubravka; Dun?erovi?, Duško; Gaji?, Milan; Paunovi?, Ivan

2012-10-01

81

Perspective on Ecotoxicology of PAHs to Fish  

Microsoft Academic Search

This article provides a perspective on recent research on the effects of PAHs on fish. Fish are visible members of aquatic communities that are vulnerable to PAH contamination. The ecotoxicology of fish and PAHs can be complex. Fish are a diverse group that can have complicated life cycles and behavior and can be exposed to PAH-contaminated sediments and water by

Dennis T. Logan

2007-01-01

82

The impact of urbanization on tropical mangroves (Fortaleza, Brazil): evidence from PAH distribution in sediments.  

PubMed

This investigation represents the first environmental diagnosis of the distribution and sources of polycyclic aromatic hydrocarbons (PAHs) in sediments from a tropical mangrove in Fortaleza, northeastern Brazil. Sediment cores from six sampling stations in the Cocó and Ceará Rivers were retrieved in June-July 2006 to determine 17 priority PAHs. The total PAH concentrations (Sigma(PAHs)) ranged from 3.04 to 2234.76 microg kg(-1)(Cocó River) and from 3.34 to 1859.21 microg kg(-1) (Ceará River). These levels are higher than those of other cities with more industrial development. PAH concentrations did not reach probable effect levels (PELs). However, from 4.5 to 87.5% of individual PAH concentrations can occasionally cause adverse biological effects for aquatic organisms. The PAH molecular ratios indicate that the PAHs in the sediment core were derived mainly from petroleum, wood, and charcoal combustion (pyrogenic source), and that atmospheric deposition and urban runoff may serve as important pathways for PAH input to the sediment. Clearly, the Sigma(PAHs) in sediments collected in the Cocó and Ceará Rivers indicate that ongoing pollution is more severe than past pollution. PMID:19889496

Cavalcante, Rivelino M; Sousa, Francisco W; Nascimento, Ronaldo F; Silveira, Edilberto R; Freire, George S S

2009-01-01

83

PAH and metal mixtures in New Orleans soils and sediments.  

PubMed

The purpose of this study is to determine the degree of PAH contamination and the association of PAHs with inorganic substances in soils and sediments of New Orleans. Bonnet Carré Spillway (BCS) (n = 5) provides modern baseline data, while urban soil samples (CTY) (n = 27) and sediment samples from Bayou St. John (BSJ) (n = 11) provide experimental data for New Orleans. Soil samples were collected from the top 2.5 cm of the surface, air-dried, and sieved (2 mm). Sediments samples were collected with a Wildco-Ekman bottom dredge, air-dried and finely ground. Accelerated solvent extraction (ASE) was used to release PAHs from the samples and analysis was conducted with gas chromatography-mass spectrometry (GC-MS). Metals were extracted using a 5:1 ratio of 1 mol/L nitric acid (room temperature) for soil and sediment samples, shaken for 2 h, centrifuged (1000 x g for 15 min) and filtered. Metal analysis was done by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Mann-Whitney tests show PAH differences (P < 0.001). Ranking of total PAHs is, BSJ sediments (10.3 mg/kg) > CTY soils (3.7 mg/kg) > BCS alluvium (0.28 mg/kg). The sum of the metals are similar for BSJ sediments (698 mg/kg) and CTY soils (679 mg/kg) and significantly lower for BCS (189 mg/kg). Manganese of these samples is similar for each site. For paired samples, Pearson Product Moment Correlation tests reveal that many PAHs are strongly associated with each other at all locations. For BCS alluvium and BSJ sediments, total PAHs are not significantly associated with total metals. For CTY, most pairs of metals are significantly associated, and total soil PAHs are strongly associated with total soil metals (correlation 0.78, P = 4.9 x 10(-4)). The linear model, total soil PAH = 136.3 + 6.25 (total soil metals) forms the basis for a predicted PAH map of New Orleans. Previous empirical research demonstrates an association between soil lead and children's lead exposure. This study indicates that PAHs are part of the soil mixture of accumulated substances and by-products of industrial society that presents exposure potential in cities. PMID:11778953

Mielke, H W; Wang, G; Gonzales, C R; Le, B; Quach, V N; Mielke, P W

2001-12-17

84

Pyroelectric array horizon sensor (PAHS)  

NASA Astrophysics Data System (ADS)

A linear pyroelectric detector array has been chosen for the application of an inexpensive earth sensor in the 14- to 16-micron range. The PAHS makes use of a modular design to allow flexibility in spacecraft mounting and mission profiles. The simplicity of the earth radiance measurement allows a variety of pitch and roll computation algorithms. These computations may be performed at the sensor or spacecraft level. The first Quantic PAHS will be flown on the Office of Naval Research's SPINSAT.

Vasey, Martin; Clark, Chris

85

Characterization of PAHs within PM 10 fraction for ashes from coke production, iron smelt, heating station and power plant stacks in Liaoning Province, China  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbons within PM 10 fraction of ashes from two coke production plants, one iron smelt plant, one heating station and one power plant were analyzed with GC-MS technique in 2009. The sum of 17 selected PAHs varied from 290.20 to 7055.72 ?g/g and the amounts of carcinogenic PAHs were between 140.33 and 3345.46 ?g/g. The most toxic ash was from the coke production plants and then from the iron smelt plant, coal-fired power plant and heating station according to BaP-based toxic equivalent factor (BaPeq) and BaP-based equivalent carcinogenic power (BaPE). PAHs profile of the iron smelt ash was significantly different from others with coefficient of divergence value higher than 0.40. Indicatory PAHs for coke production plants, heating station and coal-fired power plant were mainly 3-ring species such as Acy, Fl and Ace. While for iron smelt plant, they were Chr and BbF. Diagnostic ratios including Ant/(Ant + Phe), Flu/(Flu + Pyr), BaA/Chr, BbF/BkF, Ind/BghiP, IND/(IND + BghiP), BaP/BghiP, BaP/COR, Pyr/BaP, BaA/(BaA + Chr), BaA/BaP and BaP/(BaP + Chr) were calculated which were mostly different from other stacks for the iron smelt plant.

Kong, Shaofei; Shi, Jianwu; Lu, Bing; Qiu, Weiguang; Zhang, Baosheng; Peng, Yue; Zhang, Bowen; Bai, Zhipeng

2011-07-01

86

Occurrence and profiles of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in soils from a typical e-waste recycling area in Southeast China.  

PubMed

Surface soils collected from Taizhou, a typical e-waste recycling area in Southeast China, were analyzed for the residues of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) by using microwave-assisted extraction and gas chromatography -mass spectrometry (GC-MS). The total concentrations of 16 PAHs in US EPA's priority list (?PAHs), six indicator PCBs (?PCBs), 15 OCPs widely used in China (?OCPs) in soils ranged from 125 to 4737 ng/g (average: 854 ng/g), from not detected to 55.4 ng/g (3.16 ng/g), and from 47.9 to 820 ng/g (276 ng/g), respectively. Individual PAHs were ubiquitously found in soil samples with detected ratio of 96% and their residual levels were comparable with those of serious polluted sites. Principal component analysis in combination with diagnostic ratios suggested that the combustion of coal, wood, and plastic wastes that are closely associated with illegal and unsafe recycling operations of e-wastes was the main source of PAHs in this area. Compared with other polluted sites, the PCBs residues in soils were generally low except for those in the major recycling site. The residual levels of OCPs in this region were also relatively higher and hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT) and its metabolite forms including dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE), hexachlorobenzene (HCB), and dicofol were dominant species. The composition analysis indicated that the HCHs residues in soils might originate from the application of lindane (pure ?-HCH) and parts of DDTs possibly from the wide use of dicofol with high impurity of DDT compounds in this region. PMID:22098496

Liao, Chunyang; Lv, Jungang; Fu, Jianjie; Zhao, Zongshan; Liu, Fang; Xue, Qinzhao; Jiang, Guibin

2012-01-01

87

X-ray Spectroscopy of the Radiation-Driven Winds of Massive Stars: Line Profile and Line Ratio Diagnostics  

SciTech Connect

Massive stars drive powerful, supersonic winds via the radiative momentum associated with the thermal UV emission from their photospheres. Shock phenomena are ubiquitous in these winds, heating them to millions, and sometimes tens of millions, of degrees. The emission line spectra from the shock-heated plasma provide powerful diagnostics of the winds' physical conditions, which in turn provide constraints on models of wind shock heating. Here I show how x-ray line transfer is affected by photoelectric absorption in the partially ionized component of the wind and how it can be modeled to determine the astrophysically important mass-loss rates of these stellar winds. I also discuss how photoexcitation out of metastable excited levels of helium-like ions can provide critical information about the location of the hot plasma in magnetically channeled massive star winds.

Cohen, David H. [Swarthmore College, Department of Physics and Astronomy, 500 College Ave., Swarthmore, PA 19081 (United States)

2009-09-10

88

Toxicokinetics of PAHs in Hexagenia  

USGS Publications Warehouse

The accumulation kinetics of two waterborne polycyclic aromatic hydrocarbons (PAHs), benzo(a)pyrene (BAP) and phenanthrene (PHE), were studied in the mayfly nymph (Hexagenia limbata). The uptake clearance decreased while the bioconcentration of BAP increased with an increase in weight of the H. limbata nymph. The relationship between uptake clearance and bioconcentration for PHE was variable, and bioconcentration was greater for the heavier animals. Two kinetic models were used to evaluate the effect of nymph weight on disposition of PAHs: (a) the amount-uptake clearance model, similar to models most frequently used in environmental toxicology; and (b) a clearance-volume model, similar to models used in clinical pharmacology. The two models gave similar predictive results but were different in a few cases. These differences in common parameter estimation probably resulted from methodologies used and high data variability rather than the models themselves, since they are mathematically equal. Some of the parameters are unique to each of the models and are defined and described. The clearance of oxygen from water is inversely and linearly related to the weight of the mayfly nymphs, but oxygen clearances were always much less than the uptake clearances of the PAHs. The high PAH uptake clearance compared to oxygen clearance implies a greater surface area or efficiency for PAH accumulation from water.

Stehly, Guy R.; Landrum, Peter F.; Henry, Mary G.; Klemm, C.

1990-01-01

89

In vivo indicator dilution kinetics of PAH transport in dog kidney.  

PubMed

In vivo multiple indicator-dilution (MID) data were analyzed using a computer-assisted mathematical model of transepithelial cell transport to determine p-aminohippuric acid (PAH) transport kinetics across the proximal tubular antiluminal (ALM) and luminal (LM) membranes. A bolus of 125I-labeled albumin (plasma reference), [14C]creatinine (interstitial reference), and tracer [3H]PAH was injected into the left renal artery of anesthetized mongrel dogs (n = 21), and immediate serial sampling of the left renal venous and left and right urine outputs was performed (control). MID runs were then repeated in the same dog following intravenous infusion of unlabeled PAH. For all plasma PAH concentrations ([PAH]P), the steady-state unidirectional flux coefficients were calculated at the ALM and LM. The computer-derived unidirectional flux coefficients were in keeping with active ALM transport and passive, carrier-mediated LM transport. The Km calculated for ALM uptake (interstitium to cell) was 0.51 mM. PAH transport was completely inhibited by probenecid. As [PAH]P increased, the renal vein mean transit time ratio t[3H]PAH/t[14C]creatinine was greater than 1.0, indicating backflux from cells into the interstitium, then declined toward unity, as ALM and LM transport became saturated. This study, which used PAH as a model substrate demonstrated the feasibility of utilizing computer-assisted mathematical models to quantitate the kinetics of transepithelial transport from in vivo experimentation. PMID:2916659

Silverman, M; Whiteside, C; Lumsden, C J; Steinhart, H

1989-02-01

90

Health risk assessment of inhabitants exposed to PAHs particulate matter in air.  

PubMed

The presence of polycyclic aromatic hydrocarbon compounds (PAHs) was investigated in the particulate matter of samples taken at six sampling sites in the city of Curitiba (southern Brazil). The concentrations of suspended particulate matter ranged from 11.02 to 177.27 ng/m(3). The analysis showed that 14 of the 16 PAHs are considered a priority compound by the USEPA (US Environmental Protection Agency). The mixture of PAHs was predominantly composed of PAHs with 3 and 4 aromatic rings. Isomer pair ratios show that the main source of PAHs was from burning fossil fuels (gasoline and diesel oil), although other sources may have contributed also. Benzo(a)pyrene, (BaP), regarded one of the most toxic PAHs, was present in all samples, but with concentrations lower than the maximum concentrations defined by some EU Countries. The risk assessment was conducted using the toxic equivalent factor (TEF) considering the toxicity of the individual PAHs compared to BaP. The BaP(eq) for all samples was between 0.42-1.12 ng/m(3). The equivalent BaP(eq) indicated low health risk associated with exposure to the total PAHs content in air. The incremental lifetime cancer risk (ILCR) model was used to find the risk level for workers close to the emitting pollution sources. Outdoor exposure showed no risk for the amount of PAHs emitted. The acceptable risk is 10(-6); however, all results were lower than this value. PMID:21644163

Froehner, Sandro; Maceno, Marcell; Machado, Karina Scurupa; Grube, Marianne

2011-01-01

91

[Distribution of PAHs in surface seawater of Qingdao coast area and their preliminary apportionment].  

PubMed

The 15 parent PAHs in surface seawater from Qingdao coastal areas have been quantified by solid phase extraction-high performance liquid chromatography with fluorescent detection. The results showed that the concentration of total PAHs ranged from 8.23 ng x L(-1) to 272.02 ng x L(-1), with highest concentration near estuary and lowest at rural location. As for PAHs composition, 2, 3 ring PAHs were dominant, with percentage ranged from 52.2% to 93.8%, while the remaining were 4 to 6 ring PAHs which were ranged from 6.2% to 47.8%. The concentration of total PAHs correlates strongly with dissolved organic carbon (R = 0.944 7) in surface seawater. There was no significant fluctuation in the concentration and composition of PAHs in surface seawater from Qingdao bay area in a one-month period. The two ratios of paired PAH isomeric compounds, fluoranthene to fluoranthene plus pyrene[ Fl/(Fl + Py)] and anthracene to phenanthrene plus anthracene [An/(An + Ph)], for source apportionment suggested that various petroleum related sources, such as oil spill and petroleum combustion, were the major origin at most sampling sites, except in clean areas where PAHs were predominantly derived from coal and wood combustion. PMID:22624363

Li, Xian-Guo; Deng, Wei; Zhou, Xiao; Tang, Xu-Li; Guo, Xin-Yun; Wang, Yan

2012-03-01

92

Spatial Variation of PAH Ionization in the Orion Nebula  

NASA Astrophysics Data System (ADS)

We have carried out near-infrared imaging observations of the Orion Nebula with Wide Field Cryogenic Telescope-II. The observations covered a 1° × 1° area with a resolution of 12" through two narrow-band filters at 3.3?m, tuned to the C-H band and 3.7?m off-the-band emissions of PAHs. We detected diffuse emissions extending larger than 10' from the Trapezium cluster in both filters. We extracted the fluxes of the 3.3?m band emission (Fband) and of the 3.7?m continuum emission (Fcont) from the 3.3?m and 3.7?m filter data, respectively. The Fband and Fcont maps have similar extension over a 10' × 10' area centered on the Trapezium cluster. Although an overall morphological resemblance can be seen between the Fband and Fcont maps, the ratio Fband/Fcont varies from region to region in the area. The variation ofFband/Fcont is attributed to differences of the PAH ionization degree. Adopting emissivities of neutral and ionized PAHs, we calculated the PAH ionization degrees, and constructed a PAH ionization map in the Orion Nebula. The ionization degree varies significantly from region to region in the Orion Nebula, being ˜50% at the photo-dissociation regions of the Orion Bar, and less ionized at both sides. This partial ionization revealed based on near-infrared observations is consistent with the ionization states estimated from recent mid-infrared observations.

Haraguchi, Kentaro; Nagayama, Takahiro; Kurita, Mikio; Kino, Masaru; Sato, Shuji

2012-12-01

93

The Diagnostic Value of Transcription Factors T-bet/GATA3 Ratio in Predicting Antibody-Mediated Rejection  

PubMed Central

Background. Previous data showed that the predominance of intraglomerular T-bet or GATA3 is correlated with different mechanisms of rejection, suggesting that the ratio of T-bet/GATA3 might be used to distinguish antibody-mediated rejection (ABMR) and T-cell-mediated rejection (TCMR). Methods. We compared the intraglomerular T-bet/GATA3 ratio in ABMR and TCMR. The intragraft expression of T-bet and GATA3 was studied via immunohistochemistry. The correlation of the diagnosis of AMR with the ratio of T-bet/GATA3 was examined. Results. Both intraglomerular T-bet- and GATA3-expressing cells were increased during acute rejection. T-bet/GATA3>1 was strongly correlated with ABMR (93.3% versus 18.2%). The incidence of positive HLA-I/II antibodies and glomerulitis is significantly higher in T-bet/GATA3>1 group (P < 0.001, 0.013, resp.). The scores of peritubular capillary inflammation and glomerulitis were also higher in T-bet/GATA3>1 group (P = 0.052, P < 0.001, resp.). Nevertheless, T-bet/GATA3>1 is also correlated with C4d-negative ABMR and resistance to steroid treatment. Compared with C4d deposition, T-bet/GATA3>1 had a slight lower (90% versus 100%) specificity but a much higher (87.5% versus 68.8%) sensitivity. Conclusion. Our data suggested that intraglomerular predominance of T-bet over GATA3 might be used as diagnosis maker of ABMR in addition to C4d, especially in C4d-negative cases.

Sun, Qiquan; Zhang, Mingchao; Chen, Jinsong; Liu, Zhihong

2013-01-01

94

Diagnostic accuracy of the urinary albumin: creatinine ratio determined by the CLINITEK Microalbumin and DCA 2000+ for the rule-out of albuminuria in chronic kidney disease.  

PubMed

An increased urinary albumin excretion (albuminuria) is an established test for the early detection of renal disease and is also recognized as a risk factor for cardiovascular disease and mortality in a number of clinical settings. There is an established body of data which shows that a random urinary albumin:creatinine ratio (ACR) based on a random urine sample correlates well with 24-hour urinary albumin excretion measurement. However, there is little data to show whether specific point-of-care testing devices can be used to rule-in or rule-out increased urinary albumin excretion in comparison to a 24-hour urinary albumin excretion measurement. This study evaluated the ability to rule-in or rule-out albuminuria in a cohort of patients attending a renal outpatient clinic, using the urinary ACR determined by the CLINITEK Microalbumin (Siemens Healthcare Diagnostics Inc., Deerfield, US) a semi-quantitative strip test, and by the DCA 2000+ (Siemens Healthcare Diagnostics Inc.) a quantitative cassette based test using 3 random urine samples collected within a 24-hour period compared to 24-hour urinary albumin measurement. The CLINITEK system was shown to be a reliable test for ruling out increased urinary albumin excretion with negative likelihood ratios less than 0.05 above the 24-hour urinary albumin excretion rate of 30 mg/24 h (threshold for microalbuminuria), and less than 0.01 above the albumin excretion rate of 100 mg/24 h. The DCA 2000+ system demonstrated similar performance as a rule-out test, with likelihood ratios of less than 0.02 at 24-hour albumin excretion rates above 30 mg/24 h. Both the CLINITEK and DCA 2000+ systems could be used to rule-out increased urinary albumin excretion at the albumin excretion cut-off rate of 30 mg/24 h in this cohort of patients. PMID:18834870

Guy, Mark; Newall, Ronald; Borzomato, Joanna; Kalra, Philip A; Price, Christopher

2009-01-01

95

Investigating PAH relative reactivity using congener profiles, quinone measurements and back trajectories  

NASA Astrophysics Data System (ADS)

Vapour and particle-associated concentrations of 15 polycyclic aromatic hydrocarbons (PAH) and 11 PAH quinones have been measured in winter and summer campaigns at the rural site, Weybourne in eastern England. Concentrations of individual PAH are 20-140 times smaller than average concentrations at an English urban site. The concentrations of PAH are greatest in air masses originating from southern England relative to those from Scandinavia and the North Atlantic, while quinone to parent PAH ratios show an inverse behaviour, being highest in the more aged North Atlantic polar air masses. While concentration of 1,2-naphthoquinone decline from summer to winter, those of 1,4-naphthoquinone and anthraquinone increase suggesting a photochemical formation pathway. A comparison of congener concentration profiles measured at Weybourne with those from an urban source area (Birmingham) reveals differential losses at the rural site, especially evident in fluoranthene: pyrene ratios and consistent with the known rates of vapour phase reactions of 3 and 4 ring compounds with hydroxyl radical. The ratios of quinones to their parent PAH at Weybourne are greater than those in the urban source area indicating either more rapid loss processes for PAH, or formation of quinones during advection of the air mass, or probably both.

Alam, M. S.; Delgado-Saborit, J. M.; Stark, C.; Harrison, R. M.

2013-10-01

96

Investigating PAH relative reactivity using congener profiles, quinone measurements and back trajectories  

NASA Astrophysics Data System (ADS)

Vapour and particle-associated concentrations of 15 polycyclic aromatic hydrocarbons (PAH) and 11 PAH quinones have been measured in winter and summer campaigns at the rural site, Weybourne in eastern England. Concentrations of individual PAH are relatively smaller than average concentrations measured previously at urban sites in the UK. The concentrations of PAH of the air masses originating from southern England and mainland UK are significantly larger than those from Eastern Europe and the North Atlantic, while quinone to parent PAH ratios show an inverse behaviour, being highest in the more aged North Atlantic polar air masses. While concentrations of 1,2-naphthoquinone decline from winter to summer, those of 1,4-naphthoquinone and anthraquinone increase suggesting a photochemical formation pathway. A comparison of congener concentration profiles measured at Weybourne with those from an urban source area (Birmingham) reveals differential losses at the rural site, especially evident in fluoranthene : pyrene ratios and consistent with the known rates of vapour phase reactions of 3 and 4 ring compounds with hydroxyl radical. The ratios of quinones to their parent PAH at Weybourne are greater than those in the urban source area indicating either more rapid loss processes for PAH, or formation of quinones during advection of the air mass, or probably both.

Alam, M. S.; Delgado-Saborit, J. M.; Stark, C.; Harrison, R. M.

2014-03-01

97

Protective role of fine silts for PAH in a former industrial soil.  

PubMed

An original combined organic geochemistry and soil science approach was used to elucidate PAH availability controlling factors in a multi-contaminated industrial soil. Water granulodensimetric fractionation was applied to obtain five water-stable material fractions. These were characterized by elemental, molecular and mineral analysis, and microscopic observations. Among the different fractions, fine silts distinguished themselves by higher carbon and nitrogen contents, lower C/N ratio, an enrichment in total PAH and especially high molecular weight compounds, a coal tar signature and the lowest PAH availability. This fine silt fraction seemed to play a protective role for PAH that might be explained by its size and/or its specific reactivity. The mineral phases present in this fraction were proposed to explain the protection of organic matter. This led to a specific molecular signature of OM, having higher sorption properties both processes (sorption and mineral-bound protection) resulting in a lower PAH availability. PMID:23665618

Pernot, Audrey; Ouvrard, Stéphanie; Leglize, Pierre; Faure, Pierre

2013-08-01

98

Distribution and sources of PAHs using three pine species along the Ebro River.  

PubMed

Needles of three pine species (Pinus halepensis, Pinus pinea and Pinus nigra) were analysed to assess the occurrence of polycyclic aromatic hydrocarbons (PAHs) in 34 sites located throughout the Ebro River, in Northeast Spain. Overall, the concentration varied between 55 and 808 ng g(-1) (dry weight). The three- and four-ring PAHs were the most representative, with phenanthrene having 43% of the total PAH load and naphthalene showing a high incidence in rural areas. Despite matrix apparent similarities, P. halepensis needles revealed higher entrapment levels than P. nigra and P. pinea, the latter showing the lowest levels. The assessment of possible sources using PAH ratios (phenanthrene/anthracene and fluoranthene/pyrene) did not reveal a clear tendency regarding the distinction of petrogenic and pyrogenic sources in general, reflecting heterogeneous sources of PAHs in the Ebro area. PMID:21465131

Ratola, Nuno; Alves, Arminda; Lacorte, Sílvia; Barceló, Damià

2012-01-01

99

Isolation of adherent polycyclic aromatic hydrocarbon (PAH)-degrading bacteria using PAH-sorbing carriers  

Microsoft Academic Search

Two different procedures were compared to isolate polycyclic aromatic hydrocarbon (PAH)-utilizing bacteria from PAH-contaminated soil and sludge samples, i.e., (i) shaken enrichment cultures in liquid mineral medium in which PAHs were supplied as crystals and (ii) a new method in which PAH degraders were enriched on and recovered from hydrophobic membranes containing sorbed PAHs. Both techniques were successful, but selected

LEEN BASTIAENS; DIRK SPRINGAEL; PIERRE WATTIAU; HAUKE HARMS; RUPERT DEWACHTER; HUBERT VERACHTERT; LUDO DIELS

2000-01-01

100

Biota: sediment partitioning of aluminium smelter related PAHs and pulp mill related diterpenes by intertidal clams at Kitimat, British Columbia.  

PubMed

The question of polycyclic aromatic hydrocarbon (PAH) bioavailability and its relationship to specific PAH sources with different PAH binding characteristics is an important one, because bioavailability drives PAH accumulation in biota and ultimately the biochemical responses to the PAH contaminants. The industrial harbour at Kitimat (British Columbia, Canada) provides an ideal location to study the bioavailability and bioaccumulation of sediment hydrocarbons to low trophic level biota. Samples of soft shell clams (Mya arenaria) and intertidal sediment collected from multiple sites over six years at various distances from an aluminium smelter and a pulp and paper mill were analysed for 106 PAHs, plant diterpenes and other aromatic fraction hydrocarbons. Interpretation using PAH source ratios and multivariate data analysis reveals six principal hydrocarbon sources: PAHs in coke, pitch and emissions from anode combustion from the aluminium smelter, vascular plant terpenes and aromatised terpenes from the pulp and paper mill, petroleum PAHs from shipping and other anthropogenic activities and PAHs from natural plant detritus. Harbour sediments predominantly contain either pitch or pyrogenic PAHs from the smelter, while clams predominantly contain plant derived PAHs and diterpenes from the adjacent pulp mill. PAHs from the smelter have low bioavailability to clams (Biota-Sediment Accumulation Factors; BSAFs <1 for pitch and coke; <10 for anode combustion, decreasing to ?0.1 for the mass 300 and 302 PAHs), possibly due to binding to pitch or soot carbon matrices. Decreases in PAH isomer ratios between sediments and clams likely reflect a combination of variation in uptake kinetics of petroleum PAHs and compound specific metabolism, with the importance of petroleum PAHs decreasing with increasing molecular weight. Plant derived compounds exhibit little natural bioaccumulation at reference sites, but unsaturated and aromatised diterpenes released from resins by industrial pulping processes are readily accumulated by the clams (BSAFs >500). Thus while most of the smelter associated PAHs in sediments may not be bioavailable to benthic organisms, the plant terpenes (including retene, totarol, ferruginol, manool, dehydroabietane and other plant terpenes that form the chemical defence mechanism of conifers) released by pulp mills are bioavailable and possess demonstrated toxic properties. The large scale release of plant terpenes by some of the many pulp mills located in British Columbia and elsewhere represents a largely undocumented risk to aquatic biota. PMID:21788067

Yunker, Mark B; Lachmuth, Cara L; Cretney, Walter J; Fowler, Brian R; Dangerfield, Neil; White, Linda; Ross, Peter S

2011-09-01

101

Occupational PAH Exposures during Prescribed Pile Burns  

PubMed Central

Wildland firefighters are exposed to particulate matter and gases containing polycyclic aromatic hydrocarbons (PAHs), many of which are known carcinogens. Our objective was to evaluate the extent of firefighter exposure to particulate and PAHs during prescribed pile burns of mainly ponderosa pine slash and determine whether these exposures were correlated with changes in urinary 1-hydroxypyrene (1-HP), a PAH metabolite. Personal and area sampling for particulate and PAH exposures were conducted on the White Mountain Apache Tribe reservation, working with 21 Bureau of Indian Affairs/Fort Apache Agency wildland firefighters during the fall of 2006. Urine samples were collected pre- and post-exposure and pulmonary function was measured. Personal PAH exposures were detectable for only 3 of 16 PAHs analyzed: naphthalene, phenanthrene, and fluorene, all of which were identified only in vapor-phase samples. Condensed-phase PAHs were detected in PM2.5 area samples (20 of 21 PAHs analyzed were detected, all but naphthalene) at concentrations below 1 ?g m?3. The total PAH/PM2.5 mass fractions were roughly a factor of two higher during smoldering (1.06 ± 0.15) than ignition (0.55 ± 0.04 ?g mg?1). There were no significant changes in urinary 1-HP or pulmonary function following exposure to pile burning. In summary, PAH exposures were low in pile burns, and urinary testing for a PAH metabolite failed to show a significant difference between baseline and post-exposure measurements.

Robinson, M. S.; Anthony, T. R.; Littau, S. R.; Herckes, P.; Nelson, X.; Poplin, G. S.; Burgess, J. L.

2008-01-01

102

PAH emission from the industrial boilers.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) emitted from 25 industrial boilers were investigated. The fuels used for these 25 boilers included 21 heavy oil, two diesel, a co-combustion of heavy oil and natural gas (HO+NG) and a co-combustion of coke oven gas and blast furnace gas (COG+BFG) boilers. PAH samples from the stack flue gas (gas and particle phases) of these 25 boilers were collected by using a PAH stack sampling system. Twenty one individual PAHs were analyzed primarily by a gas chromatography/mass spectrometer (GC/MS). Total-PAH concentration in the flue gas of 83 measured data for these 25 boiler stacks ranged between 29.0 and 4250 microg/m(3) and averaged 488 microg/m(3). The average of PAH-homologue mass (F%) counted for the total-PAH mass was 54.7%, 9.47% and 15.3% for the 2-ring, 3-ring and 4-ring PAHs, respectively. The PAHs in the stack flue gas were dominant in the lower molecular weight PAHs. The emission factors (EFs) of total-PAHs were 13,300, 2920, 2880 and 208 microg/kg-fuel for the heavy oil, diesel, HO+NG and COG+BFG fueled-boiler, respectively. Nap was the most predominant PAH occurring in the stack flue gas. In addition, the EF of 21 individual PAHs in heavy-oil boiler were almost the highest among the four various fueled-boilers except for those of FL and BkF in the diesel boiler. Furthermore, the EF of total-PAHs or BaP for heavy oil were both one order of magnitude higher than that for the diesel-fueled boiler. PMID:10502602

Li, C; Mi, H; Lee, W; You, W; Wang, Y

1999-10-01

103

PAH phytoremediation: rhizodegradation or rhizoattenuation?  

PubMed

Dealing with soil contaminated with persistent organic pollutants (POP) is an increasing concern amplified by both regulatory constraints and the dramatic impact of human activities on the soil resource. The most used management options are treatments which totally eradicate the toxic compounds targeted. When possible, environmental-friendly processes should be used, and recent years have seen the emergence of green technologies using biological energies involving microorganisms (bioremediation) and plants (phytoremediation). Research has focused on phytoremediation and many have presented this technology as the process ideally combining efficiency, low cost and environmental acceptance. However, the applicability of phytoremediation on soils contaminated by bio-recalcitrant organic compounds, such as polycyclic aromatic hydrocarbons (PAH), has not yet proved as successful as expected. We propose here a review and discussion of the overall question of PAH status in soil and their potential for treatment. The limits and applicability of bioremediation technologies are discussed, and the specific beneficial effect of plants is objectively evaluated with a special interest to processes which lead to rhizoattenuation. Given the PAH high affinity to soil organic matter, availability is the main limitation to phytoremediation. In this context, bioavailability quantification remains an issue as well as the characterization of the recalcitrant fraction. PMID:24912214

Ouvrard, S; Leglize, P; Morel, J L

2014-01-01

104

Distribution, sources and potential toxicological significance of polycyclic aromatic hydrocarbons (PAHs) in surface soils of the Yellow River Delta, China.  

PubMed

PAH concentrations of 61 surface soil samples collected from the Yellow River Delta (YRD), China were measured to determine occurrence levels, sources, and potential toxicological significance of PAHs. The total concentrations of ?PAHs ranged from 27 to 753ng/g d.w., with a mean of 118±132ng/g. The highest concentrations was found in the mid-southern part of the YRD (753ng/g), which was associated with the oil exploration. The ratios indicated that the PAHs throughout the YRD were mostly of pyrogenic origin; while various sites in mid-southern part in the region were derived mainly from the petrogenic sources. Multivariate statistical analyses supported that the PAHs in surface soils of the YRD were principally from the coal and biomass combustion, petroleum spills, and/or vehicular emissions. The toxic assessment suggested that the PAHs in soils were at low potential of ecotoxicological contamination level for the YRD. PMID:24801799

Yuan, Hongming; Li, Tiegang; Ding, Xigui; Zhao, Guangming; Ye, Siyuan

2014-06-15

105

The hydrogen coverage of interstellar PAHs  

NASA Technical Reports Server (NTRS)

The rate at which the CH bond in interstellar Polycyclic Aromatic Hydrocarbons (PAHs) rupture due to the absorption of a UV photon has been calculated. The results show that small PAHs (less than or equal to 25 carbon atoms) are expected to be partially dehydrogenated in regions with intense UV fields, while large PAHs (greater than or equal to 25 atoms) are expected to be completely hydrogenated in those regions. Because estimate of the carbon content of interstellar PAHs lie in the range of 20 to 25 carbon atoms, dehydrogenation is probably not very important. Because of the absence of other emission features besides the 11.3 micrometer feature in ground-based 8 to 13 micrometer spectra, it has been suggested that interstellar PAHs are partially dehydrogenated. However, IRAS 8 to 22 micrometer spectra of most sources that show strong 7.7 and 11.2 micrometer emission features also show a plateau of emission extending from about 11.3 to 14 micrometer. Like the 11.3 micrometer feature, this new feature is attributed to the CH out of plane bending mode in PAHs. This new feature shows that interstellar PAHs are not as dehydrogenated as estimated from ground-based 8 to 13 micrometer spectra. It also constrains the molecular structure of interstellar PAHs. In particular, it seems that very condensed PAHs, such as coronene and circumcoronene, dominate the interstellar PAH mixture as expected from stability arguments.

Barker, J. R.; Cohen, M.; Tielens, Alexander G. G. M.; Allamandola, Louis J.; Barker, J. R.; Barker, J. R.

1986-01-01

106

The hydrogen coverage of interstellar PAHs  

NASA Astrophysics Data System (ADS)

The rate at which the CH bond in interstellar Polycyclic Aromatic Hydrocarbons (PAHs) rupture due to the absorption of a UV photon has been calculated. The results show that small PAHs (less than or equal to 25 carbon atoms) are expected to be partially dehydrogenated in regions with intense UV fields, while large PAHs (greater than or equal to 25 atoms) are expected to be completely hydrogenated in those regions. Because estimate of the carbon content of interstellar PAHs lie in the range of 20 to 25 carbon atoms, dehydrogenation is probably not very important. Because of the absence of other emission features besides the 11.3 micrometer feature in ground-based 8 to 13 micrometer spectra, it has been suggested that interstellar PAHs are partially dehydrogenated. However, IRAS 8 to 22 micrometer spectra of most sources that show strong 7.7 and 11.2 micrometer emission features also show a plateau of emission extending from about 11.3 to 14 micrometer. Like the 11.3 micrometer feature, this new feature is attributed to the CH out of plane bending mode in PAHs. This new feature shows that interstellar PAHs are not as dehydrogenated as estimated from ground-based 8 to 13 micrometer spectra. It also constrains the molecular structure of interstellar PAHs. In particular, it seems that very condensed PAHs, such as coronene and circumcoronene, dominate the interstellar PAH mixture as expected from stability arguments.

Barker, J. R.; Cohen, M.; Tielens, Alexander G. G. M.; Allamandola, Louis J.

1986-02-01

107

The hydrogen coverage of interstellar PAHs  

NASA Astrophysics Data System (ADS)

The rate at which the CH bond in interstellar Polycyclic Aromatic Hydrocarbons (PAHs) rupture due to the absorption of a UV photon has been calculated. The results show that small PAHs (less than or equal to 25 carbon atoms) are expected to be partially dehydrogenated in regions with intense UV fields, while large PAHs (greater than or equal to 25 atoms) are expected to be completely hydrogenated in those regions. Because estimate of the carbon content of interstellar PAHs lie in the range of 20 to 25 carbon atoms, dehydrogenation is probably not very important. Because of the absence of other emission features besides the 11.3 micrometer feature in ground-based 8 to 13 micrometer spectra, it has been suggested that interstellar PAHs are partially dehydrogenated. However, IRAS 8 to 22 micrometer spectra of most sources that show strong 7.7 and 11.2 micrometer emission features also show a plateau of emission extending from about 11.3 to 14 micrometer. Like the 11.3 micrometer feature, this new feature is attributed to the CH out of plane bending mode in PAHs. This new feature shows that interstellar PAHs are not as dehydrogenated as estimated from ground-based 8 to 13 micrometer spectra. It also constrains the molecular structure of interstellar PAHs. In particular, it seems that very condensed PAHs, such as coronene and circumcoronene, dominate the interstellar PAH mixture as expected from stability arguments.

Tielens, A. G. G. M.; Allamandola, L. J.; Barker, J. R.; Cohen, M.

108

The hydrogen coverage of interstellar PAHs  

NASA Technical Reports Server (NTRS)

The rate at which the CH bond in interstellar Polycyclic Aromatic Hydrocarbons (PAHs) rupture due to the absorption of a UV photon has been calculated. The results show that small PAHs (less than or equal to 25 carbon atoms) are expected to be partially dehydrogenated in regions with intense UV fields, while large PAHs (greater than or equal to 25 atoms) are expected to be completely hydrogenated in those regions. Because estimate of the carbon content of interstellar PAHs lie in the range of 20 to 25 carbon atoms, dehydrogenation is probably not very important. Because of the absence of other emission features besides the 11.3 micrometer feature in ground-based 8 to 13 micrometer spectra, it has been suggested that interstellar PAHs are partially dehydrogenated. However, IRAS 8 to 22 micrometer spectra of most sources that show strong 7.7 and 11.2 micrometer emission features also show a plateau of emission extending from about 11.3 to 14 micrometer. Like the 11.3 micrometer feature, this new feature is attributed to the CH out of plane bending mode in PAHs. This new feature shows that interstellar PAHs are not as dehydrogenated as estimated from ground-based 8 to 13 micrometer spectra. It also constrains the molecular structure of interstellar PAHs. In particular, it seems that very condensed PAHs, such as coronene and circumcoronene, dominate the interstellar PAH mixture as expected from stability arguments.

Tielens, A. G. G. M.; Allamandola, L. J.; Barker, J. R.; Cohen, M.

1987-01-01

109

Sirolimus and everolimus clearance in maintenance kidney and liver transplant recipients: Diagnostic efficiency of the concentration/dose ratio for the prediction of trough steady-state concentrations  

PubMed Central

Objectives Therapeutic monitoring of sirolimus and everolimus is necessary in order to minimize adverse side-effects and to ensure effective immunosuppression. A sirolimus-dosing model using the concentration/dose ratio has been previously proposed for kidney transplant patients, and the aim of our study was the evaluation of this single model for the prediction of trough sirolimus and everolimus concentrations. Methods Trough steady-state sirolimus concentrations were determined in several blood samples from each of 7 kidney and 9 liver maintenance transplant recipients, and everolimus concentrations from 20 kidney, 17 liver, and 3 kidney/liver maintenance transplant recipients. Predicted sirolimus and everolimus concentrations (Css), corresponding to the doses (D), were calculated using the measured concentrations (Css0) and corresponding doses (D0) on starting the study: Css = (Css0)(D)/D0. Results The diagnostic efficiency of the predicting model for the correct classification as subtherapeutic, therapeutic, and supratherapeutic values with respect to the experimentally obtained concentrations was 91.3% for sirolimus and 81.4% for everolimus in the kidney transplant patients. In the liver transplant patients the efficiency was 69.2% for sirolimus and 72.6% for everolimus, and in the kidney/liver transplant recipients the efficiency for everolimus was 67.9%. Conclusions The model has an acceptable diagnostic efficiency (>80%) for the prediction of sirolimus and everolimus concentrations in kidney transplant recipients, but not in liver transplant recipients. However, considering the wide ranges found for the prediction error of sirolimus and everolimus concentrations, the clinical relevance of this dosing model is weak.

Bouzas, Lorena; Hermida, Jesus

2010-01-01

110

Reflectance spectroscopy (350-2500 nm) of solid-state polycyclic aromatic hydrocarbons (PAHs)  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbons (PAHs) are organic compounds based on fused aromatic rings, and are formed in a variety of astrophysical, solar nebula and planetary processes. Polycyclic aromatic hydrocarbons are known or suspected to occur in a wide variety of planetary settings including icy satellites, Titan’s hazes, carbonaceous meteorites, comet nuclei, ring particles; and terrestrial organic-rich lithologies such as coals, asphaltites, and bituminous sands. Relatively few measurements of the visible and near-infrared spectra of PAHs exist, yet this wavelength region (350-2500 nm) is widely used for remote sensing. This study presents detailed analyses of the 350-2500 nm reflectance spectra of 47 fine-grained powders of different high-purity solid-state PAHs. Spectral properties of PAHs change with variations in the number and connectivity of linked aromatic rings and the presence and type of side-groups and heterocycles. PAH spectra are characterized by three strong features near ?880 nm, ?1145 nm, and ?1687 nm due to overtones of ?CH fundamental stretching vibrations. Some PAHs are amenable to remote detection due to the presence of diagnostic spectral features, including: Nsbnd H stretching overtones at 1490-1515 nm in NH- and NH2-bearing PAHs, aliphatic or saturated bond Csbnd H overtone vibrations at ?1180-1280 nm and ?1700-1860 nm; a broad asymmetric feature between ?1450 nm and ?1900 nm due to Osbnd H stretching overtones in aromatic alcohols, Csbnd H and Cdbnd O combinations near ?2000-2010 nm and ?2060-2270 nm in acetyl and carboxyl-bearing PAHs. Other substituents such as sulphonyl, thioether ether and carboxyl heterocycles, or cyano, nitrate, and aromatic side groups, do not produce well-resolved diagnostic spectral features but do cause shifts in the positions of the aromatic Csbnd H vibrational overtone features. Fluorescence is commonly suppressed by the presence of heterocycles, side-groups and in many non-alternant PAHs. The spectral characteristics of PAHs offer the potential, under suitable circumstances, for remote characterization of the classes of PAH present and in some cases, identification of particular heterocyclic or side-group substituents.

Izawa, M. R. M.; Applin, D. M.; Norman, L.; Cloutis, E. A.

2014-07-01

111

PAH emission from various industrial stacks  

Microsoft Academic Search

The emission of polycyclic aromatic hydrocarbons (PAHs) from various industrial stacks (blast furnace, basic oxygen furnace, coke oven, electric arc furnace, heavy oil plant, power plant and cement plant) in southern Taiwan were investigated. PAH concentrations (?g\\/N m3) and PAH emission factors (?g\\/kg feedstock) were determined. In addition to these eight stationary industrial stacks, an industrial waste incinerator, a diesel

Hsi-Hsien Yang; Wen-Jhy Lee; Shui-Jen Chen; Soon-Onn Lai

1998-01-01

112

Can PAH clusters survive in PDRs?  

NASA Astrophysics Data System (ADS)

Astronomical observations reveal an active chemistry of the carbonaceous species in photodissociation regions (PDRs), involving polycyclic aromatic hydrocarbons (PAHs) and very small carbonaceous grains. Recent analysis of mid-IR observations (Pilleri et al., submitted) support the evolutionary scenario proposed by Rapacioli et al. (2005, A&A) in which free PAHs are produced by evaporation of very small carbonaceous grains. These authors also proposed PAH clusters as models for these grains and tested this hypothesis for the specific case of coronene (C24H12) clusters (Rapacioli et al. 2006, A&A). They concluded that even though the formation of PAH clusters by collision of PAHs is efficient in PDRs, their destruction by UV photons is much faster. However, astrophysical PAHs are thought to be much larger than coronene and the stability of PAH clusters is expected to increase with the size of PAH units. We revisited this work and considered the photoevaporation of circumcoronene (C54H18) clusters. Our results lay on -(i)- molecular dynamic simulations and phase space theory to describe molecular properties and -(ii)- an astrochemical model using rate equations. We conclude about the ability of PAH clusters to survive in PDRs.

Montillaud, J.; Joblin, C.; Toublanc, D.; Simon, A.; Parneix, P.

2011-05-01

113

Fog processing of polycyclic aromatic hydrocarbons (PAH)  

NASA Astrophysics Data System (ADS)

Polyaromatic hydrocarbons (PAHs) are a class of organic species of concern for environmental and human health. The present work will present initial finding of a comprehensive study on the fate of PAHs in multiphase fog/cloud systems and across consecutive fog/smog cycles. Field observations were conducted in Fresno, CA in Winter 2010. Simultaneous measurements of gas phase, aerosol and fog PAH allowed to gain insights on the partitioning of PAH in a multiphase fog system. Partitioning results as well as temporal evolution of PAH concentrations across different phases will be discussed. Select known degradation products (oxy-PAH) from the processing of PAHs were also analyzed in the fog systems, although frequently their concentrations were close to or below detection limits, even in the polluted urban study setting. The field observations are complemented by laboratory investigations on the reactivity of PAH in fog systems, both heterogeneously and in the aqueous phase. Heterogeneously a novel reactor design is being tested to simulate fog systems and allow for repeat fog/smog cycles. A separate series of measurements investigated the processing of PAH in the aqueous phase in a solar simulator set-up.

Wang, Y.; Khadapkar, K.; Ehrenhauser, F. S.; Hutchings, J. W.; Wornat, M. J.; Valsaraj, K. T.; Herckes, P.

2010-07-01

114

PAH Degradation Capacity of Soil Microbial Communities—Does It Depend on PAH Exposure?  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants of the environment. But is their microbial degradation equally\\u000a wide in distribution? We estimated the PAH degradation capacity of 13 soils ranging from pristine locations (total PAHs ?\\u000a 0.1 mg kg?1) to heavily polluted industrial sites (total PAHs ? 400 mg kg?1). The size of the pyrene- and phenanthrene-degrading bacterial populations was determined by most

Anders R. Johnsen; Ulrich Karlson

2005-01-01

115

Multimedia Analysis of PAHs and Nitro-PAH Daughter Products in the Los Angeles Basin  

Microsoft Academic Search

ABSTRACT Polycyclic aromatic hydrocarbons,(PAHs) are toxic air pollutants which are formed during the incomplete combustion of organic materials. In the atmosphere, PAHs partition between the gas and particulate phases. PAHs which exist in the gas phase can react with hydroxy,radicals and gaseous nitrate radicals, in the presence of NOx, to form nitro-PAH derivatives. The available literature data suggest that some

Denise Yaffe; Yoram Cohen; Janet Arey; Andrew J. Grosovsky

2001-01-01

116

From PAHs to Solid Carbon  

NASA Astrophysics Data System (ADS)

Carbonaceous grains represent a major component of cosmic dust. The review will summarize new results in laboratory investigations of carbonaceous dust components. The nanometer-sized carbon particles are supposed to represent a blend of differently structured carbon including graphitic, diamond-like, fullerene-like and chain-like components on a subnanometer or nanometer scale. Recent models used to explain the structure of gas-phase condensed carbon nano-particles are discussed. Possible formation pathways of carbonaceous grains from molecular components and clusters and the role of polycyclic aromatic hydrocarbons (PAHs) and fullerenes are disclosed.

Jäger, C.; Mutschke, H.; Henning, T.; Huisken, F.

2011-03-01

117

A source mixing model to apportion PAHs from coal tar and asphalt binders in street pavements and urban aquatic sediments.  

PubMed

Present-day and more than 30 years old road and footpath pavements from Auckland, New Zealand were analysed for PAHs to test the hypothesis that coal tar based pavement binders contribute to unusually high PAH concentrations in adjacent stream and estuarine sediments. Total PAH (?(28)PAH) concentrations in the dichloromethane-soluble fraction ("binder"), comprising 5-10% of pavement mass, were as high as 200,000 mgkg(-1) (10,000 mgkg(-1) in binder+aggregate). Older and deeper pavement layers were strongly pyrogenic, whereas pavement layers from recently sealed roads had a more petrogenic composition and more than 1000 times lower ?(28)PAH concentrations. Source identification analysis using three PAH isomer ratio pairs (benz(a)anthracene/(benz(a)anthracene+chrysene); benzo(a)pyrene/(benzo(a)pyrene+benzo(e)pyrene); and indeno(1,2,3-cd)pyrene/(indeno(1,2,3-cd)pyrene+benzo(g,h,i)perylene) revealed low PAH (bitumen) pavements to have consistently lower isomer ratios than high PAH (coal tar) samples. Moreover, pavement data for one isomer ratio (e.g. benzo(a)pyrene/(benzo(a)pyrene+benzo(e)pyrene) were highly correlated with those of another isomer ratio (e.g. benz(a)anthracene/(benz(a)anthracene+chrysene) and were bounded at their lower and higher extremes by the characteristics of pure bitumen and coal tar, respectively, suggesting that PAH composition of a given pavement sample could be accounted for by conservative mixing between coal tar and bitumen as source materials. A concentration-weighted mixing model, with coal tar and bitumen as source materials, explained more than 80% of the variance in isomer ratios and enveloped the entire PAH compositional and concentration range encountered. PAH composition and concentrations in adjacent stream sediments (> 15 mgkg(-1) dry weight) were consistent with diluted coal tar material as a principal PAH source. Due to the very high PAH concentrations of coal tar, a coal tar content of as little as 0.01% of total sediment mass can account for more than 90% of PAH concentrations in adjacent stream sediments. PMID:20843538

Ahrens, Michael J; Depree, Craig V

2010-12-01

118

Assessment of PAHs in soil around the International Airport in Delhi, India.  

PubMed

Present study was undertaken to determine the level of PAH contamination due to jet turbine exhaust in the peripheral soil of the International Airport in Delhi, India. Densely populated residential areas surrounding the airport come directly under both the landing and take-off flight paths. Twelve priority polycyclic aromatic hydrocarbons (PAHs) were analyzed in the <2 mm surface soil fraction. Identification and quantification of PAHs was done by high performance liquid chromatography (HPLC). The sum of 12 PAHs ranged from 2.39 microg g(-1) to 7.53 microg g(-1) with a mean concentration of 4.43+/-1.45 microg g(-1). PAH levels observed in the present study were found to be higher as compared to most of the literature values. Among the three sampling sites selected around the International Airport, the site near landing point revealed maximum concentration of PAHs, while minimum concentration was observed at the site near take-off point. Predominance of pyrene was observed in the airport soil. Factor analysis and isomer pair ratios suggest pyrogenic origin of PAHs in the study area. PMID:18191893

Ray, Sharmila; Khillare, P S; Agarwal, Tripti; Shridhar, Vijay

2008-08-15

119

Phenols and hydroxy-PAHs (arylphenols) as tracers for coal smoke particulate matter: source tests and ambient aerosol assessments  

SciTech Connect

Source tests were conducted to analyze and characterize diagnostic key tracers for emissions from burning of coals with various ranks. Coal samples included lignite from Germany, semibituminous coal from Arizona, USA, bituminous coal from Wales, UK and sample from briquettes of semibituminous coal, bituminous coal and anthracite from China. Ambient aerosol particulate matter was also collected in three areas of China and a background area in Corvallis, OR (U.S.) to confirm the presence of tracers specific for coal smoke. The results showed a series of aliphatic and aromatic hydrocarbons and phenolic compounds, including PAHs and hydroxy-PAHs as the major tracers, as well as a significant unresolved complex mixture (UCM) of compounds. The tracers that were found characteristic of coal combustion processes included hydroxy-PAHs and PAHs. Atmospheric ambient samples from Beijing and Taiyuan, cities where coal is burned in northern China, revealed that the hydroxy-PAH tracers were present during the wintertime, but not in cities where coal is not commonly used (e.g., Guangzhou, South China). Thus, the mass of hydroxy-PAHs can be apportioned to coal smoke and the source strength modeled by summing the proportional contents of EC (elemental carbon), PAHs, UCM and alkanes with the hydroxy-PAHs. 36 refs., 2 figs., 3 tabs.

Bernd R.T. Simoneit; Xinhui Bi; Daniel R. Oros; Patricia M. Medeiros; Guoying Sheng; Jiamo Fu [Oregon State University, Corvallis, OR (United States). Environmental Sciences Program

2007-11-01

120

Polycyclic aromatic compounds (PAHs and oxygenated PAHs) and trace metals in fish species from Ghana (West Africa): bioaccumulation and health risk assessment.  

PubMed

We report the concentrations of 28 PAHs, 15 oxygenated PAHs (OPAHs) and 11 trace metals/metalloids (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Se, and Zn) in muscle and gut+gill tissues of demersal fishes (Drapane africana, Cynoglossus senegalensis and Pomadasys peroteti) from three locations along the coast of the Gulf of Guinea (Ghana). The concentrations of ?28PAHs in muscle tissues averaged 192ngg(-1) dw (range: 71-481ngg(-1) dw) and were not statistically different between locations. The concentrations of ?28 PAHs were higher in guts+gills than in muscles. The PAH composition pattern was dominated by low molecular weight compounds (naphthalene, alkyl-naphthalenes and phenanthrene). All fish tissues had benzo[a]pyrene concentrations lower than the EU limit for food safety. Excess cancer risk from consumption of some fish was higher than the guideline value of 1×10(-6). The concentrations of ?15 OPAHs in fish muscles averaged 422ngg(-1) dw (range: 28-1715ngg(-1)dw). The ?15 OPAHs/?16 US-EPA PAHs concentration ratio was >1 in 68% of the fish muscles and 100% of guts+gills. The log-transformed concentrations of PAHs and OPAHs in muscles, guts+gills were significantly (p<0.05) correlated with their octanol-water partitioning coefficients, strongly suggesting that equilibrium partitioning from water/sediment into fish tissue was the main mechanism of bioaccumulation. The trace metal concentrations in the fish tissues were in the medium range when compared to fish from other parts of the world. The concentrations of some trace metals (Cd, Cu, Fe, Mn, Zn) were higher in guts+gills than in muscle tissues. The target hazard quotients for metals were<1 and did not indicate a danger to the local population. We conclude that the health risk arising from the consumption of the studied fish (due to their PAHs and trace metals content) is minimal. PMID:24486971

Bandowe, Benjamin A Musa; Bigalke, Moritz; Boamah, Linda; Nyarko, Elvis; Saalia, Firibu Kwesi; Wilcke, Wolfgang

2014-04-01

121

THE RELATIONSHIP BETWEEN PRENATAL EXPOSURE TO AIRBORNE POLYCYCLIC AROMATIC HYDROCARBONS (PAH) AND PAH-DNA ADDUCTS IN CORD BLOOD  

PubMed Central

In a birth cohort study, we have assessed the dose-response relationship between individual measurements of prenatal airborne PAH exposure and specific PAH-DNA adducts in cord blood adjusted for maternal blood adducts and season of birth. The study uses data from an earlier established birth cohort of children in Krakow. The final analysis included 362 pregnant women who gave birth to term babies and had complete data on personal exposure in the second trimester of pregnancy to eight airborne polycyclic aromatic hydrocarbons (PAH) including benzo[a]pyrene (B[a]P), as well as DNA adducts, both in maternal and cord blood. The relation between cord blood PAH-DNA adducts and airborne prenatal PAH exposure was non-linear. While cord blood PAH-DNA adducts were significantly associated with the B[a]P exposure categorized by tertiles (nonparametric trend z = 3.50, p < 0.001), the relationship between B[a]P and maternal blood adducts was insignificant (z = 1.63, p = 0.103). Based on the multivariable linear regression model we estimated the effect of the prenatal airborne B[a]P on the level of cord blood adducts. In total, 14.8% of cord blood adducts variance was attributed to the level of maternal adducts and 3% to a higher prenatal B[a] exposure above 5.70 ng/m3. The calculated fetal/maternal blood adducts ratio (FMR) linearly increased with the B[a]P exposure (z = 1.99, p = 0.047) and was highest at B[a]P concentrations exceeding 5.70 ng/m3. In conclusion, the results support other findings that transplacental exposure to B[a[P from maternal inhalation produces DNA damage in the developing fetus. It also confirms the heightened fetal susceptibility to prenatal PAH exposure that should be a matter of public health concern particularly in the highly polluted areas because DNA adducts represent a pro-carcinogenic alteration in DNA The continuation of this birth cohort study will assess the possible health effects of fetal DNA damage on health of children and help in establishing new protective guidelines for newborns.

Jedrychowski, Wieslaw; Perera, Frederica P.; Tang, Deliang; Rauh, Virginia; Majewska, Renata; Mroz, Elzbieta; Flak, Elzbieta; Stigter, Laura; Spengler, John; Camann, David; Jacek, Ryszard

2013-01-01

122

Development of new source diagnostic methods and variance reduction techniques for Monte Carlo eigenvalue problems with a focus on high dominance ratio problems  

NASA Astrophysics Data System (ADS)

Obtaining the solution to the linear Boltzmann equation is often is often a daunting task. The time-independent form is an equation of six independent variables which cannot be solved analytically in all but some special problems. Instead, numerical approaches have been devised. This work focuses on improving Monte Carlo methods for its solution in eigenvalue form. First, a statistical method of stationarity detection called the KPSS test adapted as a Monte Carlo eigenvalue source convergence test. The KPSS test analyzes the source center of mass series which was chosen since it should be indicative of overall source behavior, and is physically easy to understand. A source center of mass plot alone serves as a good visual source convergence diagnostic. The KPSS test and three different information theoretic diagnostics were implemented into the well known KENOV.a code inside of the SCALE (version 5) code package from Oak Ridge National Laboratory and compared through analysis of a simple problem and several difficult source convergence benchmarks. Results showed that the KPSS test can add to the overall confidence by identifying more problematic simulations than without its usage. Not only this, the source center of mass information on hand visually aids in the understanding of the problem physics. The second major focus of this dissertation concerned variance reduction methodologies for Monte Carlo eigenvalue problems. The CADIS methodology, based on importance sampling, was adapted to the eigenvalue problems. It was shown that the straight adaption of importance sampling can provide a significant variance reduction in determination of keff (in cases studied up to 30%?). A modified version of this methodology was developed which utilizes independent deterministic importance simulations. In this new methodology, each particle is simulated multiple times, once to every other discretized source region utilizing the importance for that region only. Since each particle is simulated multiple times, this methodology often slows down the final keff convergence, but an increase coupling between source zones with important yet low probability interaction is observed. This is an important finding for loosely coupled systems and may be useful in their analysis. The third major focus of this dissertation concerns the use of the standard cumulative fission matrix methodology for high dominance ratio problems which results in high source correlation. Source eigenvector confidence is calculated utilizing a Monte Carlo iterated confidence approach and shown to be superior to the currently used plus and minus fission matrix methodology. Utilizing the fission matrix based approach with appropriately meshing and particle density, it is shown that the fission matrix elements tend to be independent. As a result, the keff and the source eigenvector can be calculated without bias, which is not the case for the standard methodology due to the source correlation. This approach was tested with a 1-D multigroup eigenvalue code developed for this work. A preliminary automatic mesh and particle population diagnostic were formulated to ensure independent and normal fission matrix elements. The algorithm was extended in parallel to show the favorable speedup possible with the fission matrix based approach. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http://www.uflib.ufl.edu/etd.html)

Wenner, Michael T.

123

Temporal variability of Polycyclic Aromatic Hydrocarbons (PAHs) in a receptor site of the Puebla-Tlaxcala Valley  

NASA Astrophysics Data System (ADS)

This contribution documents the presence and possible origin of PAHs, their temporal concentration patterns and correlations with other air pollutants in the so-called Puebla-Tlaxcala valley. This valley is located to the east of the Mexico City Metropolitan Area and is a very populated region which suffers of air pollution problems. Emission sources of PAHs include open burning, industrial boilers, automobiles and trucks, but vehicle emissions vary significantly depending on the use of: fuel, engine type and catalytic converter. An important emission source in the Puebla-Tlaxcala region is wood burning for cooking. Therefore, it is expected to have contributions of PAHS from this type of sources. PAHs measurements were performed in an air pollution semi-rural receptor site (Chipilo) southwest the City of Puebla, using an aerosol photoelectric sensor (PAS 2000 CE) to measure the concentration of PAHs and a diffuser charger (DC 2000 CE) to evaluate the active surface (DC) of the particles. The measuring period included March and April of 2012 during the ozne season in central Mexico. The use of these two sensors in parallel has been identified as a fingerprint technique to identify different types of particles from several combustion processes and is a useful tool to identify quantitatively the major source of emissions, as well as to describe thephysical and chemical characteristics of the particles. Correlations between PAHs and DC, with NOx and CO, together with an analysis of atmospheric transport may approximate the possible origin of these particles. The coefficient PAHs / DC associated with backward trajectory analysis represents a tool to identify potential areas of emission. The correlation between PAHs and NOx emissions reflects association with diesel combustion, while the correlation between PAHs and CO, the combustion of gasoline. The results show that vehicle emissions are the major source of PAHs with an associated increase in the concentration of PAHs in the morning, when there is more vehicular traffic. The time series of PAHs also exhibit synchronized peaks of PAHs and DC that correspond to hours of traffic which shows the relationship of PAHs with DC. However, correlations of PAHs with DC show a relatively strong scattering suggesting that aerosols are a mixture of particles of different sources and different ages. Throughout the day is observed the aging of primary combustion particles due to the secondary aerosols coating. This coating may prolong the life time of the PAHs in the atmosphere. Also occurs a decrease in the ratio PAHs / DC during the day. Low ratios indicate the abundance of large particles, whereas high ratios indicate abundance dominated by small particle emissions from diesel engines. The resulting correlations show a significant linear trend evolution of PAHs with NOx, indicating that the PAHs are associated with the combustion of diesel, and a linear trend of PAHs with DC for each type of aerosol combustion, while the correlation of PAHs with CO results in an exponential trend which implies that PAHs are related to the combustion of diesel.

Padilla, Z. V.; Torres, R.; Ruiz Suarez, L.; Molina, L. T.

2013-05-01

124

Polycyclic aromatic hydrocarbons (PAHs) in the atmospheres of two French alpine valleys: sources and temporal patterns  

NASA Astrophysics Data System (ADS)

Alpine valleys represent some of the most important crossroads for international heavy-duty traffic in Europe, but the full impact of this traffic on air quality is not known due to a lack of data concerning these complex systems. As part of the program "Pollution des Vallées Alpines" (POVA), we performed two sampling surveys of polycyclic aromatic hydrocarbons (PAHs) in two sensitive valleys: the Chamonix and Maurienne Valleys, between France and Italy. Sampling campaigns were performed during the summer of 2000 and the winter of 2001, with both periods taking place during the closure of the "Tunnel du Mont-Blanc". The first objective of this paper is to describe the relations between PAH concentrations, external parameters (sampling site localization, meteorological parameters, sources), and aerosol characteristics, including its carbonaceous fraction (OC and EC). The second objective is to study the capacity of PAH profiles to accurately distinguish the different emission sources. Temporal evolution of the relative concentration of an individual PAH (CHR) and the PAH groups BghiP+COR and BbF+BkF is studied in order to differentiate wood combustion, gasoline, and diesel emissions, respectively. The results show that the total particulate PAH concentrations were higher in the Chamonix valley during both seasons, despite the cessation of international traffic. Seasonal cycles, with higher concentrations in winter, are also stronger in this valley. During winter, particulate PAH concentration can reach very high levels (up to 155 ng.m-3) in this valley during cold anticyclonic periods. The examination of sources shows the impact during summer of heavy-duty traffic in the Maurienne valley and of gasoline vehicles in the Chamonix valley. During winter, Chamonix is characterized by the strong influence of wood combustion in residential fireplaces, even if the temporal evolution of specific PAH ratios are difficult to interpret. Information on sources given by PAH profiles can only be considered in qualitative terms.

Marchand, N.; Besombes, J. L.; Chevron, N.; Masclet, P.; Aymoz, G.; Jaffrezo, J. L.

2004-08-01

125

The thermodynamic landscape of methanogenic PAH degradation  

PubMed Central

Summary Methanogenic degradation of polycyclic aromatic hydrocarbons (PAHs) has long been considered impossible, but evidence in contaminated near surface environments and biodegrading petroleum reservoirs suggests that this is not necessarily the case. To evaluate the thermodynamic constraints on methanogenic PAH degradation we have estimated the Gibbs free energy values for naphthalene, phenanthrene, anthracene, pyrene and chrysene in the aqueous phase, and used these values to evaluate several possible routes whereby PAHs may be converted to methane. Under standard conditions (25°C, solutes at 1?M concentrations, and gases at 1?atm), methanogenic degradation of these PAHs yields between 209 and 331?kJ?mol?1. Per mole of methane produced this is 27–35?kJ?mol?1, indicating that PAH?based methanogenesis is exergonic. We evaluated the energetics of three potential PAH degradation routes: oxidation to H2/CO2, complete conversion to acetate, or incomplete oxidation to H2 plus acetate. Depending on the in situ conditions the energetically most favourable pathway for the PAH?degrading organisms is oxidation to H2/CO2 or conversion into acetate. These are not necessarily the pathways that prevail in the environment. This may be because the kinetic theory of optimal length of metabolic pathways suggests that PAH degraders may have evolved towards incomplete oxidation to acetate plus H2 as the optimal pathway.

Dolfing, Jan; Xu, Aiping; Gray, Neil D.; Larter, Stephen R.; Head, Ian M.

2009-01-01

126

PAHS IN THE LAKE MICHIGAN AQUATIC ECOSYSTEM  

EPA Science Inventory

PAHs in the Lake Michigan Aquatic Ecosystem. Fernandez, JD*, Burkhard, LP, Cook, PM, Nichols, JW, Mid-Continent Ecology Division, U.S. EPA, Duluth MN. In this study, we are investigating the accumulation of PAHs in the Lake Michigan food web. Focusing on EPA's 16 "Priority Po...

127

Reduction of PAH and soot precursors in benzene flames by addition of ethanol.  

PubMed

A one-dimensional premixed flame model (PREMIX) and schemes resulting from the merging of validated kinetic schemes for the oxidation of the components of the present mixtures (benzene and ethanol) were used to investigate the effect of oxygenated additives on aromatic species, which are known to be soot precursors, in fuel-rich benzene combustion. The specific flames were low-pressure (45 mbar), laminar, premixed flames at an equivalence ratio of 2.0. The blended fuels were formed by incrementally adding 4% wt of oxygen (ethanol) to the neat benzene flame and by keeping the inert mole fraction (argon) and the equivalence ratio constants. Special emphasis was directed toward the causes for the concentration-dependent influence of the blends on the amount of polycyclic aromatic hydrocarbons (PAHs) formed. The effects of oxygenate addition to the benzene base flame were seen to result in interesting differences, especially regarding trends to form PAH. The modeling results indicated that the concentration of acetylene and propargyl radicals, the main PAH precursors, as well as the PAH amounts were lower in the flame of the ethanol-benzene fuel mixture than in the pure benzene flame and that all of the formed PAHs were issued from the phenyl radical. Finally, the modeling results provided evidence that the PAH reduction was a result of simply replacing "sooting" benzene with "nonsooting" ethanol without influencing the combustion chemistry of the benzene. PMID:22429107

Golea, Djemaa; Rezgui, Yacine; Guemini, Miloud; Hamdane, Soumia

2012-04-12

128

Removal of PAHs from highly contaminated soils found at prior manufactured gas operations.  

PubMed

Removal of PAHs from highly contaminated soil found at a manufactured gas site was evaluated using solvent washing with mixed solvents. The following solvents were considered as water miscible co-solvents in mixed solvents: ethanol, 2-propanol, acetone, and 1-pentanol. In batch solvent extraction of soil, ethanol and 2-propanol were selected as primary components of mixed solvents in addition to 1-pentanol. Using ternary solutions containing either ethanol or 2-propanol with a volume fraction of 1-pentanol ranging from 5 to 25% and a water volume fraction ranging from 5 to 30%, ethanol was more effective than 2-propanol in extracting PAHs from soil. A solvent mixture of 5% 1-pentanol, 10% water and 85% ethanol was selected as the extraction solvent. Using a 1g:4ml soil:solvent extraction ratio, extraction kinetics showed that from 65 to 90% of the extractable PAHs were removed within an hour of contact between soil and solvent. Using this 1g:4ml extraction ratio, PAHs were removed in a three-stage cross-current solvent washing process where the same batch of soil was extracted with clean solvent for 1h in each stage. PAH removals in three-stage cross-current solvent washing were comparable to PAH removals obtained with Soxhlet extraction. PMID:11080576

Khodadoust, A P; Bagchi, R; Suidan, M T; Brenner, R C; Sellers, N G

2000-12-30

129

Spitzer Infrared Spectrograph Observations of Infrared-Luminous Galaxies at Moderate Redshift: Diagnostics of AGN and Star Formation  

NASA Astrophysics Data System (ADS)

We use mid-Infrared (MIR) spectroscopy from Spitzer to study star-formation and AGN processes in 65 IR-luminous galaxies at 0.02 < z < 0.6. The MIR spectra cover wavelengths 5-38µm, spanning the strongest polycyclic aromatic hydrocarbon (PAH) features and other important diagnostic lines. Our sample of galaxies spans the full range of rest-frame (u-r) optical color with F(24µm) > 1.2 mJy, which corresponds to total IR luminosity, L(IR)=1010-1012L?, with a median L(IR) 1011L?. We select a subset of galaxies with Spitzer IRAC 3.6-8.0µm colors indicative of warm dust heated by an AGN. Compared to IR-luminous galaxies with no indications of AGN, these IRAC-selected AGN show weaker PAH emission, which we attribute to an increase in MIR continuum from the AGN. We find that the luminosity in the PAH features correlates strongly with [Ne II] ?12.8µm emission in both the AGN and non-AGN subsamples. We find no measurable difference between the luminosity ratios of ionized and neutral PAHs, specifically the 7.7-to-11.3µm PAH ratio. This suggests that the AGN do not preferentially excite or destroy the PAH molecules on galaxy-wide scales, and in all IR-selected galaxies the PAH luminosity correlates strongly with the total SFR. A small subset of galaxies show a strong excess of [O IV] ?25.9µm emission for their PAH emission, indicating the presence of heavily-obscured AGN in galaxies. We compare the position of both the IR-AGN to other galaxies on an optical color-magnitude relation. The IRAC-selected AGN populate a range of color, primarily in the ``green valley'', implying their hosts are a mix of starburst and post-starburst galaxies. The [O IV]-excess objects in our sample lie toward the red end of the ``green valley''. Given their placement on the color-magnitude diagram, and their weak PAH emission, we conclude their IR luminosity is dominated by processes associated with the AGN.

Shipley, Heath V.; Papovich, C.; Dey, A.; Jannuzi, B.; Rieke, G.; Weiner, B.

2012-01-01

130

Desorption of polycyclic aromatic hydrocarbons (PAH`s) from calcite and quartz sediments to seawater  

SciTech Connect

Polycyclic aromatic hydrocarbons (PAH`s) are ubiquitous hydrophobic organic pollutants in the marine environment. Many of the PAM`s are classified as possible carcinogens or mutagens, therefore they are of considerable concern to human and environmental health. The highest concentrations are found in coastal regions due to anthropogenic activities including oil spills, tanker operations, incomplete fossil fuel combustion and runoff. The sources and distribution of PAM`s in sediments are fairly well known, while the fate and transport of PAH`s in the marine environment are less known. Desorption is an important factor influencing the fate and transport of hydrophobic molecules at the seawater/sediment interface. The desorption of PAH`s from contaminated marine sediments to the water column/pore water affects the availability of the pollutant to biota. The sorption of PAH`s is determined in part by the organic carbon content of the sediments. The presence of dissolved organic carbon (DOC) in the water column may also influence sorption of hydrophobic molecules. DOC may play an important role in the fate and transport of PAH`s in coastal regions where DOC concentrations are highest. This study presents the results of the desorption of nine PAHs from sediments to seawater. Factors observed included carbon content of sediments, sediment mineralogy, fulvic acid addition to seawater and dissolved organic carbon in seawater.

Sutton, P.L.; Van Vleet, E.S. [Univ. of South Florida, St. Petersburg, FL (United States)

1996-12-31

131

Infrared fluorescence from PAHs in the laboratory  

NASA Technical Reports Server (NTRS)

Several celestial objects, including UV rich regions of planetary and reflection nebulae, stars, H II regions, and extragalactic sources, are characterized by the unidentified infrared emission bands (UIR bands). A few years ago, it was proposed that polycyclic aromatic hydrocarbon species (PAHs) are responsible for most of the UIR bands. This hypothesis is based on a spectrum analysis of the observed features. Comparisons of observed IR spectra with lab absorption spectra of PAHs support the PAH hypothesis. An example spectrum is represented, where the Orion Bar 3.3 micron spectrum is compared with the absorption frequencies of the PAHs Chrysene, Pyrene, and Coronene. The laser excited 3.3 micron emission spectrum is presented from a gas phase PAH (azulen). The infrared fluorescence theory (IRF) is briefly explained, followed by a description of the experimental apparatus, a report of the results, and discussion.

Cherchneff, Isabelle; Barker, John R.

1989-01-01

132

Bayesian Source Separation for PAH Spectra  

NASA Astrophysics Data System (ADS)

The Aromatic Infrared Bands (AIBs) are prominent features of many galactic spectra in the infrared and are strongly associated with star-forming regions. Polycyclic Aromatic Hydrocarbons (PAHs) are a leading contender as the source for this emission. Unequivocally establishing this identification has been difficult since the AIBs do not appear to be the result of emission from a small, tractable number of PAHs. Rather the observed emission bands appear to be composed of the contributions from possibly hundreds of different PAHs, neutral and ionized, each with its own distinctive spectrum. A major step toward verifying the PAH hypothesis would be to quantitatively establish how well the observed AIBs can be explained, or not explained, as the combination of known PAH spectra. To date this problem has been attacked by either manually superimposing individual PAH spectra or by using non-negative least squares. We explain how both of these approaches have serious deficiencies. We then describe our progress in applying Bayesian source separation techniques to this difficult problem. In this phase of our investigation, we have worked with theoretically generated PAH spectra at a single temperature composed of combinations of arbitrarily selected PAHs with added Gaussian noise. First, we show how the non-negative least squares approach fares as a function of PAH composition, noise level, and spectral resolution. Next, we outline our Bayesian approach, which relies on Skilling's nested sampling algorithm. This approach allows us to find highly probable solutions and evaluate the uncertainties in our estimates by sampling the posterior. Moreover, this algorithm also enables us to compute the evidence provided by the data as well as visualize the posterior probability in the high-dimensional hypothesis space generated by the numerous combinations of possible PAH contributions. This research is supported by NASA Applied Information Systems Research Grant 05-AISR05-0143.

Carbon, Duane F.; Tse, M. K.; Knuth, K. H.

2006-12-01

133

Diagnostic accuracy of spot urinary protein and albumin to creatinine ratios for detection of significant proteinuria or adverse pregnancy outcome in patients with suspected pre-eclampsia: systematic review and meta-analysis  

PubMed Central

Objective To determine the diagnostic accuracy of two “spot urine” tests for significant proteinuria or adverse pregnancy outcome in pregnant women with suspected pre-eclampsia. Design Systematic review and meta-analysis. Data sources Searches of electronic databases 1980 to January 2011, reference list checking, hand searching of journals, and contact with experts. Inclusion criteria Diagnostic studies, in pregnant women with hypertension, that compared the urinary spot protein to creatinine ratio or albumin to creatinine ratio with urinary protein excretion over 24 hours or adverse pregnancy outcome. Study characteristics, design, and methodological and reporting quality were objectively assessed. Data extraction Study results relating to diagnostic accuracy were extracted and synthesised using multivariate random effects meta-analysis methods. Results Twenty studies, testing 2978 women (pregnancies), were included. Thirteen studies examining protein to creatinine ratio for the detection of significant proteinuria were included in the multivariate analysis. Threshold values for protein to creatinine ratio ranged between 0.13 and 0.5, with estimates of sensitivity ranging from 0.65 to 0.89 and estimates of specificity from 0.63 to 0.87; the area under the summary receiver operating characteristics curve was 0.69. On average, across all studies, the optimum threshold (that optimises sensitivity and specificity combined) seems to be between 0.30 and 0.35 inclusive. However, no threshold gave a summary estimate above 80% for both sensitivity and specificity, and considerable heterogeneity existed in diagnostic accuracy across studies at most thresholds. No studies looked at protein to creatinine ratio and adverse pregnancy outcome. For albumin to creatinine ratio, meta-analysis was not possible. Results from a single study suggested that the most predictive result, for significant proteinuria, was with the DCA 2000 quantitative analyser (>2 mg/mmol) with a summary sensitivity of 0.94 (95% confidence interval 0.86 to 0.98) and a specificity of 0.94 (0.87 to 0.98). In a single study of adverse pregnancy outcome, results for perinatal death were a sensitivity of 0.82 (0.48 to 0.98) and a specificity of 0.59 (0.51 to 0.67). Conclusion The maternal “spot urine” estimate of protein to creatinine ratio shows promising diagnostic value for significant proteinuria in suspected pre-eclampsia. The existing evidence is not, however, sufficient to determine how protein to creatinine ratio should be used in clinical practice, owing to the heterogeneity in test accuracy and prevalence across studies. Insufficient evidence is available on the use of albumin to creatinine ratio in this area. Insufficient evidence exists for either test to predict adverse pregnancy outcome.

2012-01-01

134

Mid-IR Galaxy Classification Based on Silicate Obscuration and PAH Equivalent Width  

Microsoft Academic Search

We present a new diagnostic diagram for mid-infrared spectra of infrared\\u000agalaxies based on the equivalent width of the 6.2 micron PAH emission feature\\u000aand the strength of the 9.7 micron silicate feature. Based on the position in\\u000athis diagram we classify galaxies into 9 classes ranging from\\u000acontinuum-dominated AGN hot dust spectra and PAH-dominated starburst spectra to\\u000aabsorption-dominated spectra

H. W. W. Spoon; J. A. Marshall; J. R. Houck; M. Elitzur; L. Hao; L. Armus; B. R. Brandl; V. Charmandaris

2006-01-01

135

Effect of land use activities on PAH contamination in urban soils of Rawalpindi and Islamabad, Pakistan.  

PubMed

Urbanization can increase the vulnerability of soils to various types of contamination. Increased contamination of urban soils with polycyclic aromatic hydrocarbon (PAH) could relate to increased number of petrol pump stations and mechanical workshops-a phenomenon that needs to be constantly monitored. This study was undertaken to explore the soil PAH levels in Rawalpindi and Islamabad urban areas in relation to land use activities. Composite soil samples from petrol pump stations and mechanical workshops (n?=?32) areas were evaluated for five PAHs--naphthalene, phenanthrene, pyrene, benzo[a]pyrene, and indeno(1,2,3-cd)pyrene-and compared with control area locations with minimum petroleum-related activity (n?=?16). Surface samples up to 3 cm depth were collected and extraction of analytes was carried out using n-hexane and dichloromethane. Prior to running the samples, standards (100 ?g ml(-1)) were run on HPLC to optimize signal to noise ratio using acetonitrile as mobile phase at a flow rate of 1.25 ml/min at 40 °C. Significant differences between petrol pump stations and mechanical workshop areas were observed for individual PAH as well as with control area soil samples. Naphthalene was found to be the most abundant PAH in soil, ranging from 2.47 to 24.36 mg kg(-1). Correlation between the benzo[a]pyrene (BaP) level in soil and the total PAH concentration (r?=?0.82, P?PAH pollution. A clear segregation between petrogenic and pyrogenic sources of contamination was observed when low molecular weight PAHs detected in soil was plotted against high molecular weight PAHs. The former source comprised lubricants and used engine oil found at mechanical workshops, whereas the latter could be mostly attributed to vehicular emission at petrol pumps. The results indicate that PAH contamination in urban areas of Rawalpindi and Islamabad has direct relevance with land use for petroleum activity. We conclude that in order to reduce the soil PAH exposure in urban environment, petrol pumps and mechanical workshops must be shifted to less densely populated areas because of their role as important point sources for PAH emission. PMID:23595691

Ud Din, Ikhtiar; Rashid, Audil; Mahmood, Tariq; Khalid, Azeem

2013-10-01

136

Influence and interactions of multi-factors on the bioavailability of PAHs in compost amended contaminated soils.  

PubMed

Compost amendment to contaminated soils is a potential approach for waste recycling and soil remediation. The relative importance and interactions of multiple factors on PAH bioavailability in soils were investigated using conjoint analysis and five-way analysis of variance. Results indicated that soil type and contact time were the two most significant factors influencing the PAH bioavailability in amended soils. The other two factors (compost type and ratio of compost addition) were less important but their interactions with other factors were significant. Specifically the 4-factor interactions showed that compost addition stimulated the degradation of high molecular PAHs at the initial stage (3month) by enhancing the competitive sorption within PAH groups. Such findings suggest that a realistic decision-making towards hydrocarbon bioavailability assessment should consider interactions among various factors. Further to this, this study demonstrated that compost amendment can enhance the removal of recalcitrant hydrocarbons such as PAHs in contaminated soils. PMID:24875869

Wu, Guozhong; Li, Xingang; Kechavarzi, Cédric; Sakrabani, Ruben; Sui, Hong; Coulon, Frédéric

2014-07-01

137

The interstellar chemistry of PAH cations.  

PubMed

Diffuse interstellar bands (DIBs) are mysterious absorption lines in the optical spectra of stars, and have been known for 75 years. Although it is widely believed that they arise from gas-phase organic molecules (rather than from dust grains) in the interstellar medium, no consensus has been reached regarding their precise cause. The realization that many emission features in astronomical infrared spectra probably arise from polycyclic aromatic hydrocarbons (PAHs), which may themselves be very abundant in the interstellar medium, has led to the suggestion that ionized PAHs might be the source of the DIBs. Laboratory investigations have revealed that small, positively charged PAHs in matrices have absorption features that bear some resemblance to DIBs, but no clear identification of any DIB with any specific PAH cation has yet been made. Here we report a laboratory study of the chemical reactivity of PAH cations (C6H6+, C10H8+ and C16H10+) in the gas phase. We find that these PAH cations are very reactive, and are therefore unlikely to survive in high abundances in the interstellar medium. Rather, such molecules will react rapidly with hydrogen, and we therefore suggest that the resulting protonated PAH cations (and species derived from them) should become the focus of future searches for a correspondence between molecular absorption features and the DIBs. PMID:9440689

Snow, T P; Le Page, V; Keheyan, Y; Bierbaum, V M

1998-01-15

138

Concentration and Photochemistry of PAHs, NPAHs, and OPAHs and Toxicity of PM2.5 during the Beijing Olympic Games  

PubMed Central

Atmospheric particulate matter with diameter <2.5 um (PM2.5) was collected at Peking University (PKU) in Beijing, China before, during, and after the 2008 Olympics and analyzed for black carbon (BC), organic carbon (OC), lower molecular weight (MW<300) and MW302 Polycyclic Aromatic Hydrocarbons (PAHs), nitrated PAHs (NPAHs) and oxygenated PAHs (OPAHs). In addition, the direct and indirect acting mutagenicity of the PM2.5 and the potential for DNA damage to human lung cells were also measured. Significant reductions in BC (45%), OC (31%), MW< 300 PAH (26% – 73%), MW 302 PAH (22% – 77%), NPAH (15% – 68%) and OPAH (25% – 53%) concentrations were measured during the source control and Olympic Olympic period. However, the mutagenicity of the PM2.5 was significantly reduced only during the Olympic period. The PAH, NPAH, and OPAH composition of the PM2.5 was similar throughout the study, suggesting similar sources during the different periods. During the source control period, the parent PAH concentrations were correlated with NO, CO, and SO2 concentrations, indicating that these PAHs were associated with both local and regional emissions. However, the NPAH and OPAH concentrations were only correlated with the NO concentrations, indicating that the NPAH and OPAH were primarily associated with local emissions. The relatively high 2-nitrofluoranthene/1-nitropyrene ratio (25 – 46) and 2-nitrofluoranthene/2-nitropyrene ratio (3.4 – 4.8), suggested a predominance of photochemical formation of NPAHs through OH-radical-initiated reactions in the atmosphere. On average, the ?NPAH and ?OPAH concentrations were 8% of the parent PAH concentrations, while the direct-acting mutagenicity (due to the NPAH and OPAH) was 200% higher than the indirect-acting mutagenicity (due to the PAH). This suggests that NPAH and OPAH make up a significant portion of the overall mutagenicity of PM2.5 in Beijing.

WANG, WENTAO; JARIYASOPIT, NARUMOL; SCHRLAU, JILL; JIA, YULING; TAO, SHU; YU, TIAN-WEI; DASHWOOD, RODERICK H.; ZHANG, WEI; WANG, XUEJUN; SIMONICH, STACI L. MASSEY

2011-01-01

139

Distribution of PAHs in surface soils from petroleum handling facilities in Calabar.  

PubMed

The level of concentrations of polycyclic aromatic hydrocarbons (PAHs) in surface soils from petroleum handling facilities (kerosene tank, generating plant, petrol stations, mechanic workshops, leaking pipeline and air port fuel dump) from Calabar metropolis southeastern Nigeria was determined by gas chromatography/ mass spectrometry. The results show that total polycyclic aromatic hydrocarbons (PAHs) varied from 1.80 to 334.43 mg/kg with a mean of 50.31 mg/kg. The lowest value of 1.80 mg/kg was obtained from petrol station while the highest value of 334.43 mg/kg was obtained from facility characterised by petrol stations and mechanic workshops. The ratio of phenanthrene/anthracene and fluoranthene/pyrene, varied from 0.43 to 27.72 and from 0.14 to 17.76 respectively. These ratios indicate various sources for the PAH. The two to three ring PAHs are the most abundant. Based on the PAH ratios and content alone it is not possible to distinguish between contribution from motor vehicle exhaust, gasoline spillage, used engine oil or petroleum production. However, considering the area of the study, it is very likely that the major source of soil contamination is originating from petroleum product. PMID:17106773

Nganje, T N; Edet, A E; Ekwere, S J

2007-07-01

140

Distribution patterns and sources of metals and PAHs in an intensely urbanized area: The Acerra-Pomigliano-Marigliano conurbation (Italy)  

NASA Astrophysics Data System (ADS)

The main objective of the URGE (URban GEochemistry) project is to define, map and interpretate the geochemical baseline patterns of potentially harmful elements and compounds in the soils of 12 european urban areas using shared procedures for both sampling and analytical techniques. In Italy, in the framework of the URGE project, the north-eastern sector of the Napoli metropolitan area, namely the Acerra-Pomigliano-Marigliano conurbation, has undergone a geochemical characterization based on 145 soil samples collected over an area of 90 sq km. This area has been selected on the basis of the results obtained from previous regional studies [1, 2, 3] and because of the presence on its territory of an historical industrial settlement (formerly devoted to plastic materials and synthetic fibres production) which was partly dismantled and party converted to a power plant fuelled by palm oil. Furthermore, in March 2009 also an incinerator came into operation in the northern sector of the study area. The main objective of the study carried out for the Acerra-Pomigliano-Marigliano conurbation was to define the local geochemical baselines for both 53 elements (among which the toxic ones) and some organic compounds, including PAHs and OCPs. The study also aimed at supporting epidemiological researches at local scale and at establishing a record of the actual environmental conditions to evaluate the future impact of the incinerator on both the territory and the public health. Results obtained showed that Pb, Zn and V exceed the trigger limits established by the Italian Environmental law (D.Lgs. 152/2006) especially in correspondence with the most densely populated areas of the conurbation and where the traffic load is higher (Road junctions and fast lanes). Furthermore, most of the soils collected in the surroundings of the urbanized areas resulted to be generally enriched in Cu, Co, Cd, Be, Ni and P suggesting the presence of a relevant influence on their chemistry of an agricultural intensive land use. PAHs distribution pattern showed anomalous values across the whole study area. Especially, Benzo[a]pyrene values exceeds the trigger limits established by the Italian Environmental law (D.Lgs. 152/2006) in most of the analyzed soils and the diagnostic ratios calculated among several PAHs compounds suggested that the biomass burning in the rural sector of the study area could be a relevant source of pollution. The palm oil fuelled power plant in the northern sector of Acerra could not be excluded as a source of PAHs in the environment. [1] Albanese et al (2007) JGE 93, 21-34. [2] Cicchella et al (2008) GEEA 8 (1), 19-29. [3] De Vivo et al (2006) Aracne Editrice, Roma. 324 pp.

Albanese, Stefano; Lima, Annamaria; Rezza, Carmela; Ferullo, Giampiero; De Vivo, Benedetto; Chen, Wei; Qi, Shihua

2014-05-01

141

Composition, sources, and potential toxicology of polycyclic aromatic hydrocarbons (PAHs) in agricultural soils in Liaoning, People's Republic of China.  

PubMed

Surface soil (0-20 cm) samples (n?=?143) were collected from vegetable, maize, and paddy farmland used for commercial crops in Liaoning, China. Sixteen priority polycyclic aromatic hydrocarbons (PAHs) listed in US Environmental Protection Agency were analyzed by high-performance liquid chromatography using a fluorescence detector. The soil concentrations of the 16 PAH ranged from 50 to 3,309 ng/g with a mean of 388 ng/g. The highest concentration of total PAHs found in soil of the vegetable farmland was 448 ng/g in average, followed by maize and paddy with total PAHs of 391 and 331 ng/g, respectively. Generally, the low molecular weight PAHs were more predominant than the high molecular weight PAHs in most of the soils. The evaluation of soil PAH contamination based on the Canadian criterion indicated that only naphthalene, phenanthrene, and pyrene were over the target values in several sampling sites. Isomer pair ratios and principal component analysis indicated that biomass and coal combustion were the main sources of PAHs in this area. And the average value of total B[a]Peq concentration in vegetable soils was higher than paddy and maize soils. We suggest that biomass burning should be abolished and commercial farming should be carried out far from the highways to ensure the safety of food products derived from commercial farming. PMID:22707148

Cao, Xiu Feng; Liu, Miao; Song, Yu Fang; Ackland, M Leigh

2013-03-01

142

Determination of some carcinogenic PAHs with toxic equivalency factor along roadside soil within a fast developing northern city of India  

NASA Astrophysics Data System (ADS)

The objective of the present study was to ascertain contamination levels, distribution behaviour and PAHs exposure during summer, winter and autumn during 2011-2012 in one of the developing cities of northern India. Average PAHs concentration was found to be 18.17, 4.04 and 16.38 ?g g -1, whereas, concentration of 16 individual PAHs was found to vary between 0.02 and 200.23, 0.008 and 28.4 ?g g -1, and 0.01 and 252.55 ?g g -1 during summer, winter and autumn seasons, respectively. The average concentration of low and high carcinogenic PAHs during summer, winter and autumn was found to be 5.1 and 31.29, 2.1 and 6.4, 4.74 and 35.08 ?g g -1 at most intercepts. The average ratio of low to high carcinogenic PAHs was found to be 1:6, 1:3, 1:7.6 during summer, winter and autumn, respectively. Five ringed PAHs were found in higher concentration in all seasons. Dib(ah)A and B(a)P were the two individual PAHs found in highest concentration during summer, winter and autumn seasons. Two tailed T-test was applied for authenticity of the results. Toxic equivalency factor of B(a)P and Dib(ah)A was maximum as compared to other PAHs. The study could be of great significance for the planners while considering environmental remedial measures.

Kumar, A. Vaneet; Kothiyal, N. C.; Kumari, Saruchi; Mehra, R.; Parkash, A.; Sinha, R. R.; Tayagi, S. K.; Gaba, R.

2014-05-01

143

Sedimentary records of PAHs in a sediment core from tidal flat of Haizhou Bay, China.  

PubMed

The concentrations and depositional fluxes of polycyclic aromatic hydrocarbons (PAHs) were investigated in a dated sediment core collected from a tidal flat in Haizhou Bay, China. The USEPA's 16 priority PAH concentrations ranged from 72.51 ng g(-1) dw in 1969 to 805.21 ng g(-1) dw in 2010, while the deposition fluxes were in the range of 102.36-861.02 ng cm(-2) yr(-1). The PAH concentrations and fluxes changed dramatically with depth, suggesting changes in energy usage and corresponding closely with the historical economic development of eastern China. The levels of PAHs slightly increased from the late 1970s, following China's "Reform and Open" policy of 1978; however, a drastic increase in the concentration of PAHs observed in 1990 was indicative of the rapid growth in coal and petroleum incomplete combustion byproducts, which was associated with the increase in economic development in this area. Furthermore, isomer ratio analysis and principle component analysis revealed the main anthropogenic pyrolytic source that causes PAH contamination in the coastal sediment. PMID:23500827

Zhang, Rui; Zhang, Fan; Zhang, Tian-Cheng

2013-04-15

144

PAH in the laboratory and interstellar space  

NASA Technical Reports Server (NTRS)

The theory that polycyclic aromatic hydrocarbons (PAHs) are a constituent of the interstellar medium, and a source of the IR emission bands at 3.3, 6.2, 7.7, 8.6, and 11.3 microns is being studied using PAH containing acid insoluble residue of the Orgueil CI meteorite and coal tar. FTIR spectra of Orgueil PAH material that has undergone thermal treatment, and a solvent insoluble fraction of coal tar that has been exposed to hydrogen plasma are presented. The UV excided luminescence spectrum of a solvent soluble coal tar film is also shown. Comparison of the lab measurements with observations appears to support the interstellar PAH theory, and shows the process of dehydrogenation expected to take place in the interstellar medium.

Wdowiak, Thomas J.; Flickinger, Gregory C.; Boyd, David A.

1989-01-01

145

SOURCES OF HUMAN EXPOSURE TO AIRBORNE PAH  

EPA Science Inventory

Personal exposures to airborne particulate polycyclic aromatic hydrocarbons (PAHs) were studied in several populations in the US, Japan, and Czech Republic. Personal exposure monitors, developed for human exposure biomonitoring studies were used to collect fine particles (...

146

Isolation of adherent polycyclic aromatic hydrocarbon (PAH)-degrading bacteria using PAH-sorbing carriers  

SciTech Connect

Two different procedures were compared to isolate polycyclic aromatic hydrocarbon (PAH)-utilizing bacteria from PAH-contaminated soil and sludge samples, i.e., (i) shaken enrichment cultures in liquid mineral medium in which PAHs were supplied as crystals and (ii) a new method in which PAH degraders were enriched on and recovered from hydrophobic membranes containing sorbed PAHs. Both techniques were successful, but selected from the same source different bacterial strains able to grow on PAHs as the sole source of carbon and energy. The liquid enrichment mainly selected for Sphingomonas spp., whereas the membrane method exclusively led to the selection of Mycobacterium spp. Furthermore, in separate membrane enrichment set-ups with different membrane types, three repetitive extragenic palindromic PCR-related Mycobacterium strains were recovered. The new Mycobactereium isolates were strongly hydrophobic and displayed the capacity to adhere strongly to different surfaces. One strain, Mycobacterium sp. LB501T, displayed an unusual combination of high adhesion efficiency and an extremely high negative charge. This strain may represent a new bacterial species as suggested by 16S rRNA gene sequence analysis. These results indicate that the provision of hydrophobic sorbents containing sorbed PAHs in the enrichment procedure discriminated in favor of certain bacterial characteristics. The new isolation method is appropriate to select for adherent PAH-degrading bacteria, which might be useful to biodegrade sorbed PAHs in soils and sludge.

Bastiaens, L.; Springael, D.; Wattiau, P.; Harms, H.; DeWachter, R.; Verachtert, H.; Diels, L.

2000-05-01

147

Photochemistry of PAHs on Arctic Snow Grains  

NASA Astrophysics Data System (ADS)

Photochemical reactions can greatly influence the chemistry of surface snow and transform many of the organic pollutants in snowpacks. Little is known about the rates and mechanisms of these photochemical processes, but they likely play a large role in determining lifetimes of many pollutants in snow. Our goal here is to understand the fate of one class of organic pollutants, polycyclic aromatic hydrocarbons (PAH's), in snow and ice. PAH's are ubiquitous in the environment and have well-studied toxicities. We have focused on the degradation kinetics of phenanthrene, pyrene, and fluoranthene on ice, as these are the most abundant PAH's found in Arctic snow. Laboratory photochemistry experiments were conducted using frozen solutions of PAH's illuminated with simulated solar light. Direct photolysis rates were measured using frozen solutions of the PAH's in Milli-Q with added solutes, whereas indirect photo-oxidation reactions with hydroxyl radical were measured in similar frozen solutions with added hydrogen peroxide as a source of ·OH. Using data from our group's previous and ongoing research on the levels of hydroxyl radical in Summit snow, we have been able to begin to assess the relative significance of indirect photo-oxidation and direct photolysis of PAH's as mechanisms of degradation for these compounds on snow and ice. Summit field data indicate that direct photolysis is the main mechanism of phenanthrene degradation, and laboratory experiments confirm this finding for all three PAH compounds. Data extrapolated to Summit conditions suggests that indirect photo-oxidation via ·OH accounts for only a small fraction (about 2 to 4%) of PAH degradation on ice. Our direct photolysis data suggest that PAH lifetimes on snow and ice under Arctic conditions are on the order of 1 to 7 hours during mid-summer. These results are based on photolysis experiments conducted on ice pellets made from PAH solutions. Actual snowpack lifetimes are likely to be longer, given that PAH's are most likely to be associated with particulate matter (e.g, deposited atmospheric aerosols) in the snow.

Ram, K.; Anastasio, C.

2007-12-01

148

PAHFIT: Properties of PAH Emission  

NASA Astrophysics Data System (ADS)

PAHFIT is an IDL tool for decomposing Spitzer IRS spectra of PAH emission sources, with a special emphasis on the careful recovery of ambiguous silicate absorption, and weak, blended dust emission features. PAHFIT is primarily designed for use with full 5-35 micron Spitzer low-resolution IRS spectra. PAHFIT is a flexible tool for fitting spectra, and you can add or disable features, compute combined flux bands, change fitting limits, etc., without changing the code. PAHFIT uses a simple, physically-motivated model, consisting of starlight, thermal dust continuum in a small number of fixed temperature bins, resolved dust features and feature blends, prominent emission lines (which themselves can be blended with dust features), as well as simple fully-mixed or screen dust extinction, dominated by the silicate absorption bands at 9.7 and 18 microns. Most model components are held fixed or are tightly constrained. PAHFIT uses Drude profiles to recover the full strength of dust emission features and blends, including the significant power in the wings of the broad emission profiles. This means the resulting feature strengths are larger (by factors of 2-4) than are recovered by methods which estimate the underlying continuum using line segments or spline curves fit through fiducial wavelength anchors.

Smith, J. D.; Draine, Bruce

2012-10-01

149

PAH emission from the industrial boilers  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs) emitted from 25 industrial boilers were investigated. The fuels used for these 25 boilers included 21 heavy oil, two diesel, a co-combustion of heavy oil and natural gas (HO+NG) and a co-combustion of coke oven gas and blast furnace gas (COG+BFG) boilers. PAH samples from the stack flue gas (gas and particle phases) of these 25

Chun-Teh Li; Hsiao-Hsuan Mi; Wen-Jhy Lee; Wen-Chun You; Ya-Fen Wang

1999-01-01

150

[Research on PAHs fingerprints of vehicle discharges].  

PubMed

Air samples of 14 PAHs were collected from vehicle discharges of different types, oils, and mileages and analyzed by HPLC. It showed that the total PAHs discharged from the vehicle in 30 minutes were 41.53-121.1 micrograms/m3, among which, BaA was the most predominant, about 33.3%, followed by Naphthalene, Benzo (ghi) pyrene and In (1,2,3-cd) pyrene, about 16.8%, 12.9% and 12.1%, respectively. Diesel vehicle discharged more total PAHs compared to gasoline vehicle. The two vehicles all exhausted much BaA and Naph, however diesel vehicle mainly emitted Ac, Fluor, Bghip, In, while gasoline discharged mainly Bghip, In, BkF. PAHs with five or more rings in gasoline discharges were relatively higher than those in diesel discharges, however to 3-ring PAHs, diesel vehicle produced more than gasoline vehicle. As for vehicle of different mileage, there was a clear increase for almost all PAHs, especially Flur, Py, BaP, Bghip. PMID:12916197

Zhu, Lizhong; Wang, Jing; Du, Ye; Xu, Qingqing

2003-05-01

151

PAHs in soils: Sorption versus degradation - elucidation of rate-limiting processes  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbons (PAHs) belong to the class of persistent organic pollutants, and are of special interest due to their ubiquituous distribution in the environment at relatively high concentrations. Subsequent to their emmission into the environment through incomplete combustion processes of natural and anthropogenic sources (e.g. vulcano eruptions, forest fires, industry, traffic), PAHs can be transported over long distances. Following atmospheric deposition they accumulate in particular in top-soils and have been found to be stable over long periods of time (decades to centuries). Based on that this study targets on the elucidation of the long-term PAH-fate in top-soils by means of degradation experiments under well-controlled laboratory conditions with well mixed batch experiments at a water to solids ratio 10:1. From a rural site in the Black Forest Mountains, Germany, top-soil samples were taken, which contains approximately 7-8 mg ?18 PAHs per kg soil. This soil was sieved through 2 mm to sort out stones, roots- and leaf-parts and homogenised afterwards. Within the first month of incubation a depletion of native PAHs were observed. However, an exhaustive sequential extraction using accelerated solvent extraction with 3 cycles of acteone and 4 cycles of toluene (100 bar pressure, 10 min static time, 100°C and 150°C respectively) revealed a reduced extractability of PAHs subsequent to incubation. In order to stimulate PAH degradation a second experiment with a higher water to solid ratio (1000:1) was carried out, and phenanthrene was spiked to the water phase of this set up. Results revealed a reduction of phenanthrene concentration more likely to be due to sorption rather than degradation. The set up was changed to aqueous soil solutions without soil in the batch and spiked again with phenanthrene. Degradation of phenanthrene occurred within 10 days in these batches. The experiments show that the microorganisms present in the Black Forest soil are capable to degrade PAHs. Nevertheless strong sorption and high organic carbon content in this soil prevent these microorganisms from degrading the native PAHs. The results were implemented into a mass balance model considering both, sorption and degradation. The calculations were conducted with first order rate constant ? taken from the non-soil-containing experiment, and revealed a half-life of phenanthrene up to almost one century. Keywords: PAH, degradation, sorption

Herklotz, Ilka; Gocht, Tilman; Grathwohl, Peter

2010-05-01

152

PAH-DNA Adducts, Cigarette Smoking, GST Polymorphisms, and Breast Cancer Risk  

PubMed Central

Background Polycyclic aromatic hydrocarbons (PAHs) may increase breast cancer risk, and the association may be modified by inherited differences in deactivation of PAH intermediates by glutathione S-transferases (GSTs). Few breast cancer studies have investigated the joint effects of multiple GSTs and a PAH biomarker. Objective We estimated the breast cancer risk associated with multiple polymorphisms in the GST gene (GSTA1, GSTM1, GSTP1, and GSTT1) and the interaction with PAH–DNA adducts and cigarette smoking. Methods We conducted unconditional logistic regression using data from a population-based sample of women (cases/controls, respectively): GST polymorphisms were genotyped using polymerase chain reaction and matrix-assisted laser desorption/ionization time-of-flight assays (n = 926 of 916), PAH–DNA adduct blood levels were measured by competitive enzyme-linked immunosorbent assay (n = 873 of 941), and smoking status was assessed by in-person questionnaires (n = 943 of 973). Results Odds ratios for joint effects on breast cancer risk among women with at least three variant alleles were 1.56 [95% confidence interval (CI), 1.13–2.16] for detectable PAH–DNA adducts and 0.93 (95% CI, 0.56–1.56) for no detectable adducts; corresponding odds ratios for three or more variants were 1.18 (95% CI, 0.82–1.69) for ever smokers and 1.44 (95% CI, 0.97–2.14) for never smokers. Neither interaction was statistically significant (p = 0.43 and 0.62, respectively). Conclusion We found little statistical evidence that PAHs interacted with GSTT1, GSTM1, GSTP1, and GSTA1 polymorphisms to further increase breast cancer risk.

McCarty, Kathleen M.; Santella, Regina M.; Steck, Susan E.; Cleveland, Rebecca J.; Ahn, Jiyoung; Ambrosone, Christine B.; North, Kari; Sagiv, Sharon K.; Eng, Sybil M.; Teitelbaum, Susan L.; Neugut, Alfred I.; Gammon, Marilie D.

2009-01-01

153

PAHs in organic film on glass window surfaces from central Shanghai, China: distribution, sources and risk assessment.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) concentrations were analysed in the organic film on the glass surfaces of different functional areas in central Shanghai. Concentration levels of total PAHs in the organic film ranged from 1,348.5 to 4,007.9 ng m(-2). The concentration of PAHs was lowest in parks and green spaces (1,348.5 ng m(-2)) and highest in traffic zones (4,007.9 ng m(-2)). A concentration gradient of total PAHs was observed as follows: traffic zones > commercial areas > cultural and educational areas > parks and green spaces. The distribution of PAHs was characterised by 3-4 ring PAHs in the study areas. The most abundant PAHs were phenanthrene (20.5 %), fluorene (16.7 %), pyrene (12.4 %) and chrysene (Chry) (11.2 %). The mass of the bulk film was composed of organic and inorganic compounds and ranged from 246 to 1,288 mg m(-2). The bulk film thickness varied from 144 to 757 nm in the different functional areas. The ratios of An/178 and Fl/202 and principal component analysis suggested that PAHs came mainly from the mixed sources of fossil fuel, coal and incomplete combustion of biomass. Benzo[a]anthracene (BaA)/Chry is not suitable for use as a tracer for the transmission process of PAHs because of the rapid depletion of BaA in the organic film by photooxidation during daylight hours. The concentration of benzo[a]pyrene equivalent (BaPeq) varied from 21 to 701 ng g(-1), and the major carcinogenic contributors of the 16 PAHs were BaP, DahA, B[b/k]F and InP, accounting for 83 % of BaPeq. PMID:24337860

Yu, Yingpeng; Yang, Yi; Liu, Min; Zheng, Xin; Liu, Ying; Wang, Qing; Liu, Weiya

2014-08-01

154

Polycyclic Aromatic Hydrocarbons (PAHs) Slurry Phase Bioremediation of a Manufacturing Gas Plant (MGP) Site Aged Soil  

Microsoft Academic Search

Bench scale tests have been carried out in order to investigatebioremediation feasibility of a Manufacturing Gas Plant site(Bovisa Gasometri – MI – I) aged soil, highly contaminated bypolyaromatic hydrocarbons (PAHs) and mineral oils. Biodegradationstudies were carried out at 22 °C in a slurry system reactor, with a solid to liquid ratio of 10% w\\/w. Three testswere performed, over a period

Sabrina Saponaro; Luca Bonomo; Gianniantonio Petruzzelli; Laura Romele; Meri Barbafieri

2002-01-01

155

Polycyclic aromatic hydrocarbons (PAHs), nitrated PAHs and oxygenated PAHs in ambient air of the Marseilles area (South of France): Concentrations and sources  

Microsoft Academic Search

Ambient measurements (gas+particle phases) of 15 polycyclic aromatic hydrocarbons (PAHs), 17 nitrated PAHs (NPAHs) and 9 oxygenated PAHs (OPAHs) were carried out during July 2004 on three different sites (urban, sub-urban and rural) in the region of Marseilles (South of France). Atmospheric concentrations of these classes of polyaromatics are great of interest because of their high potential mutagenicity and carcinogenicity.

Alexandre Albinet; Eva Leoz-Garziandia; Hélène Budzinski; Eric ViIlenave

2007-01-01

156

Computational Study of the Thermodynamics of Atmospheric Nitration of PAHs via OH-Radical-Initiated Reaction  

NASA Astrophysics Data System (ADS)

Nitrated polycyclic aromatic hydrocarbons (NPAHs) are an important class of PAH derivatives that are more toxic than their parent PAHs (1) and are emitted from direct emission and secondary emission to the atmosphere. The secondary emissions, particularly the OH-radical initiated and NO3-radical-initiated reactions, have been shown to influence the NPAH concentrations in the atmosphere. Gas-phase reactions are thought to be the major sources of NPAHs containing four or fewer rings (2). Besides NPAHs, PAHs lead to a number of other products including oxygenated, hydroxy substituted and ring-opened PAH derivatives (3). For some PAHs, the OH-initiated and NO3-initiated reactions result in the formation of different NPAH isomers, allowing the ratio of these isomers to be used in the determination of direct or secondary emission sources. Previous studies have shown that the PAH gas-phase reactions with OH radical is initiated by the addition of OH radical to the aromatic ring to form hydroxycyclohexadienyl radicals (4). In the presence of NO2, these reactive intermediates readily nitrate with the elimination of water (4). The hydroxycyclohexadienyl-type radical intermediates are also prone to react with other species in the atmosphere or revert back to the original compound (3). The objective of this study was to investigate the thermodynamics of PAH nitration through day-time OH-radical-initiated reactions. The theoretical investigation were carried out using Density Functioanl Theory (B3LYP) and the 6-31G(d) basis set, as implemented in Gaussian03. A number of different PAHs were studied including fluoranthene, pyrene, as well as the molecular weight 302 PAHs such as dibenzo[a,l]pyrene. Computations were also used to predict unknown NPAHs formed by OH-radical-initiated reaction. All intermediates for the OH-radical addition and the following nitration were computed. We have discovered that the thermodynamic stability of the intermediates involved in the PAH oxygenation and nitration pathways are critical in explaining the atmospheric abundances of NPAHs. Specifically, we have found that the experimentally most abundant species had the most stable intermediates. Interestingly, the overall free energy of reaction was not a factor in determining the relative abundances of NPAHs.

Jariyasopit, N.; Cheong, P.; Simonich, S. L.

2011-12-01

157

A search for PAHs in astrophysical environments  

NASA Astrophysics Data System (ADS)

We present the results of a dedicated search for the spectral signatures in the visible range of neutral polycyclic aromatic hydrocarbons (PAHs) in astronomical observations representing various astrophysical environments, probing a total column of line of sight material corresponding to Av ˜50. Laboratory measurements of PAHs in simulated astrophysical conditions are now available (see contribution of Salama et al.) which provide for the first time the exact wavelengths for the spectral features of these molecules, as well as detailed information on the intrinsic line profiles and oscillator strengths. These measurements therefore allow a direct comparison to astronomical observations and an estimate of -- or upper limit to -- the abundance of individual PAHs in space. As the column densities for individual PAHs in interstellar or circumstellar lines of sight are expected to be very low, such a comparison and analysis requires astronomical observations at very high signal to noise. We present such a data set here for lines of sight representing diffuse clouds and circumstellar environments of carbon stars, and their comparison with gas phase spectra of a representative set of free, cold PAHs. Acknowledgements: This work is supported by the NASA Astronomy and Physics Research and Analysis (APRA) Program of the Science Mission Directorate. This research was performed while J.C., X.T. and L.B. held a National Research Council Research Associateship Award at NASA-Ames Research Center.

Cami, J.; Tan, X.; Biennier, L.; Salama, F.

2005-05-01

158

A Search for PAHs in Astrophysical Environments  

NASA Technical Reports Server (NTRS)

We present the results of a dedicated search for the spectral signatures in the visible range of neutral polycyclic aromatic hydrocarbons (PAHs) in astronomical observations representing various astrophysical environments, probing a total column of line of sight material corresponding to Av=50. Laboratory measurements of PAHs in simulated astrophysical conditions are now available (see contribution of Salama et al.) which provide for the first time the exact wavelengths for the spectral features of these molecules, as well as detailed information on the intrinsic line profiles and oscillator strengths. These measurements therefore allow a direct comparison to astronomical observations and an estimate of, or upper limit to, the abundance of individual PAHs in space. As the column densities for individual PAHs in interstellar or circumstellar lines of sight are expected to be very low, such a comparison and analysis requires astronomical observations at very high signal to noise. We present such a data set here for lines of sight representing diffuse clouds and circumstellar environments of carbon stars, and their comparison with gas phase spectra of a representative set of free, cold PAHs.

Salama, F.; Cami, J.; Tan, X.; Biennier, L.

2005-01-01

159

From the Laboratory to Space: Neutral and Ionized PAHs in Translucent Interstellar Clouds  

NASA Astrophysics Data System (ADS)

We describe and discuss the laboratory experiments that were designed to test the proposal of relating the origin of some of the diffuse interstellar bands (DIBs) to neutral and ionized polycyclic aromatic hydrocarbons (PAHs) present in diffuse interstellar clouds. The spectra of several cold, isolated gas-phase PAH ions and neutral molecules have been measured using the COSmIC laboratory facility at NASA-Ames and are compared with an extensive set of astronomical spectra of reddened, early type stars. The COSmIC facility combines a supersonic free jet expansion with discharge plasma and high-sensitivity cavity ringdown spectroscopy to provide experimental conditions that closely mimic the interstellar conditions. This comparison provides - for the first time - accurate upper limits for the abundances of specific PAH molecules and ions along specific lines-of-sight. Something that is not attainable from infrared observations alone. The comparison of these unique laboratory data with high resolution, high S/N ratio astronomical observations leads to major findings regarding the column densities of the individual PAH molecules and ions that are probed in this survey and leads to clear and unambiguous conclusions regarding the expected abundances for PAHs of various sizes and charge states in these environments. This quantitative survey of neutral and ionized PAHs in the optical range opens the way for unambiguous quantitative searches of PAHs and complex organics in a variety of interstellar and circumstellar environments. Acknowledgements: F.S. acknowledges the support of the NASA’s Space Mission Directorate APRA Program. The authors are deeply grateful to the ESO archive as well as to the ESO staff members for their active support.

Salama, Farid; Galazutdinov, G.; Biennier, L.; Krelowski, J.

2012-05-01

160

Sedimentary record of PAHs in the Barigui River and its relation to the socioeconomic development of Curitiba, Brazil.  

PubMed

Concentrations of polycyclic aromatic hydrocarbons (PAHs) were determined in a sediment core collected from the Barigui River, in Curitiba, South Brazil. The USEPA's 16 priority PAH concentrations ranged from 39ng g(-1) to 2350ng g(-1) of dry sediment over a period that corresponds temporally to between ca. 1855 and 2011. The concentrations and patterns of PAH distribution changed over this time period and may be associated with several episodes in the Curitiba's history. Two major PAHs concentration peaks occurred in approximately 1910 and 1970, which might reflect population increases due to immigration programs in the 1890s and the sudden economic development that occurred in Brazil from 1960 to 1980, "The Economic Miracle Period", respectively. Isomeric ratios revealed that the PAHs had predominantly pyrolytic sources. The population, number of highways and electric energy consumption of Curitiba, as indices of socioeconomic development, were positively correlated with PAH deposition in the sediment core from 1855 to 1970, indicating the influence of socioeconomic development on the environmental load of sedimentary PAHs. PMID:24636886

Machado, Karina S; Figueira, Rubens C L; Côcco, Lilian C; Froehner, Sandro; Fernandes, Cristovão V S; Ferreira, Paulo A L

2014-06-01

161

Occurrence, finger printing and ecological risk assessment of polycyclic aromatic hydrocarbons (PAHs) in the Chenab River, Pakistan.  

PubMed

Seventeen polycyclic aromatic hydrocarbons (PAHs) were studied in surface waters (including particulate phase) from the Chenab River, Pakistan and ranged from 289-994 and 437-1290 ng l(-1) in summer and winter (2007-09), respectively. Concentrations for different ring-number PAHs followed the trend: 3-rings > 2-rings > 4-rings > 5-rings > 6-rings. The possible sources of PAHs are identified by calculating the indicative ratios; appropriating petrogenic sources of PAHs in urban and sub-urban regions with pyrogenic sources in agricultural region. Factor analysis based on principal component analysis identified the origins of PAHs from industrial activities, coal and trash burning in agricultural areas and municipal waste disposal from surrounding urban and sub-urban areas via open drains into the riverine ecosystem. Water quality guidelines and toxic equivalent factors highlighted the potential risk of low molecular weight PAHs to the aquatic life of the Chenab River. The flux estimated for PAHs contaminants from the Chenab River to the Indus River was >50 tons/year. PMID:22006353

Farooq, Samiya; Eqani, Syed Ali-Musstjab-Akber-Shah; Malik, Riffat Naseem; Katsoyiannis, Athanasios; Zhang, Gan; Zhang, Yanlin; Li, Jun; Xiang, Liu; Jones, Kevin C; Shinwari, Zabta Khan

2011-11-01

162

Emissions of gas- and particle-phase polycyclic aromatic hydrocarbons (PAHs) in the Shing Mun Tunnel, Hong Kong  

NASA Astrophysics Data System (ADS)

Real-world vehicle emission factors for seventeen gas and particulate polycyclic aromatic hydrocarbons (PAHs) were quantified in the Shing Mun Tunnel, Hong Kong during summer and winter 2003. Naphthalene, acenaphthylene, and acenaphthene were the most abundant gas PAHs while fluoranthene and pyrene were the most abundant in the particle phase. Most (98%) of the gas PAHs consisted of two- and three-aromatic rings whereas most of the particle-phase PAHs were in four- (˜60%) and five-ring (˜17%) for fresh exhaust emissions. Average emission factors for the gas- and particle PAHs were 950-2564 ?g veh -1 km -1 and 22-354 ?g veh -1 km -1, respectively. Good correlations were found between diesel markers (fluoranthene and pyrene; 0.85) and gasoline markers (benzo[ghi]perylene and indeno[1,2,3-cd]pyrene; 0.96). Higher PAH emission factors were associated with a higher fraction of diesel-fueled vehicles (DV) passing through the tunnel. Separate emission factors were determined from diesel and non-diesel exhaust by the regression intercept method. The average PAH emission factor (i.e., sum of gas and particle phases) from DV (3085 ± 1058 ?g veh -1 km -1) was ˜5 times higher than that from non-diesel-fueled vehicles (NDV, 566 ± 428 ?g veh -1 km -1). Ratios of DV to NDV emission factors were high for diesel markers (>24); and low for gasoline markers (<0.4).

Ho, K. F.; Ho, Steven Sai Hang; Lee, S. C.; Cheng, Y.; Chow, Judith C.; Watson, John G.; Louie, P. K. K.; Tian, Linwei

2009-12-01

163

Emissions of PAHs from indoor crop residue burning in a typical rural stove: Emission factors, size distributions and gas-particle partitioning  

PubMed Central

Indoor combustion of crop residues for cooking or heating is one of the most important emission sources of polycyclic aromatic hydrocarbons (PAHs) in developing countries. However, data on PAH emission factors (EFs) for burning crop residues indoor, particularly those measured in field were scarce, leading to large uncertainties in the emission inventories. In this study, EFs of PAHs for nine commonly used crop residues burnt in a typical Chinese rural cooking stove were measured in simulated kitchen. The measured EFs of total PAHs averaged at 63 ± 37 mg/kg, ranging from 27 to 142 mg/kg, which were higher than those measured in chamber experiments, implying that the laboratory experiment based emission and risk assessment should be carefully reviewed. EFs of gaseous and particulate phase PAHs were 27 ± 13 and 35 ± 23 mg/kg, respectively. Composition profiles and isomer ratios of emitted PAHs were characterized. Stepwise regressions found that modified combustion efficiency and fuel moisture were the most important factors affecting the emissions. 80 ± 6 % of PAHs were associated with PM2.5 and the mass percentage of PAHs in fine particles increased as the molecular weight increased. For freshly emitted PAHs, absorption into organic carbon, rather than adsorption, dominated the gas-particle partitioning.

Shen, Guofeng; Wang, Wei; Yang, Yifeng; Ding, Junnan; Xue, Miao; Min, Yujia; Zhu, Chen; Shen, Huizhong; Li, Wei; Wang, Bin; Wang, Rong; Wang, Xilong; Tao, Shu; Russell, Armistead G.

2011-01-01

164

Enrichment of polycyclic aromatic hydrocarbons (PAHs) in mariculture sediments of Hong Kong.  

PubMed

Surface and core sediments collected from six fish farms in Hong Kong and from reference sites were investigated for the enrichment and sources of polycyclic aromatic hydrocarbons (PAHs). Moderately high SigmaPAH16 levels (123-947 ng g(-1), mean: 450 ng g(-1)) were found in the surface aquaculture sediments. In comparison with the sediments from the reference sites, the average enrichment percentage of total organic carbon (TOC) and PAHs in surface sediments were 21.4 and 43.8%, respectively, and in the core sediments, 24.6 and 73.7%, respectively. Mathematical source apportionment analyses (i.e. isomer ratios, hierarchical cluster analysis, principal components analysis with multiple linear regression analysis) suggested a higher percentage of petrogenic sources in aquaculture sediments. The fish feeds might be the main source of the enriched PAHs in the aquaculture sediments. To our knowledge, this is the first study showing that PAHs in aquaculture sediments could be attributed to human aquaculture activities. PMID:20708314

Wang, Hong-Sheng; Liang, Peng; Kang, Yuan; Shao, Ding-Ding; Zheng, Gene J; Wu, Sheng-Chun; Wong, Chris K C; Wong, Ming H

2010-10-01

165

Vertical distribution of polycyclic aromatic hydrocarbons (PAHs) in Hunpu wastewater-irrigated area in northeast China under different land use patterns.  

PubMed

The concentrations of polycyclic aromatic hydrocarbons (PAHs) were determined in groundwater and soil profiles from upland field and paddy field in the Hunpu wastewater-irrigated area of northeast China. In the study area, the peak concentrations of total PAHs were within or just below the topsoil, and the contents decline with depth at various trend verified by the Spearman's rank correlation test. The total PAH concentrations in upland soil layers ranged from 46.8 to 2,373.0 microg/kg (dry wt.), while the concentrations in paddy soil layers ranged from 23.1 to 1,179.1 microg/kg (dry wt.). The 16 priority PAHs were all detected in the analyzed soil samples, and naphthalene (Nap), phenanthrene (Phe), fluoranthene (Fla), chrysene (Chr), and benzo[a]pyrene (Bap) were selected for further study in terms of their vertical distributions. The concentrations of both total and individual PAHs in upland soil were generally higher than those in the corresponding layers of paddy soil. The concentrations of total and individual PAH were notably different between the corresponding horizons in upland and paddy soil were probably attribute to the different sources and properties of the PAHs and soil; different methods of soil tillage and plant growing. Special PAH compound ratios, such as phenanthrene/anthracene, fluoranthene/pyrene, LMW/HMW, and parent PAH ratios (Ant/178, Fla/202, BaA/228, and Ilp/276) were used to identify the source of soil PAHs. The data suggests that the possible sources of PAHs in the Hunpu wastewater-irrigation area are the incomplete combustion of coal, petroleum and crude oil, automobile exhausts. These sources lead to pollution of the soil and groundwater by wet/dry deposition and vertical downward migration. PMID:17899417

Xiao, Ru; Du, Xiaoming; He, Xiaozhen; Zhang, Yuejin; Yi, Zhihua; Li, Fasheng

2008-07-01

166

HELIOS: A helium line-ratio spectral-monitoring diagnostic used to generate high resolution profiles near the ion cyclotron resonant heating antenna on TEXTOR  

NASA Astrophysics Data System (ADS)

Radial profiles of electron temperature and density are measured at high spatial (~1 mm) and temporal (>=10 ?s) resolution using a thermal supersonic helium jet. A highly accurate detection system is applied to well-developed collisional-radiative model codes to produce the profiles. Agreement between this measurement and an edge Thomson scattering measurement is found to be within the error bars (<~20%). The diagnostic is being used to give profiles near the ion cyclotron resonant heating antenna on TEXTOR to better understand RF coupling to the core.

Unterberg, E. A.; Schmitz, O.; Fehling, D. H.; Stoschus, H.; Klepper, C. C.; Muñoz-Burgos, J. M.; Van Wassenhove, G.; Hillis, D. L.

2012-10-01

167

HELIOS: A helium line-ratio spectral-monitoring diagnostic used to generate high resolution profiles near the ion cyclotron resonant heating antenna on TEXTOR  

SciTech Connect

Radial profiles of electron temperature and density are measured at high spatial ({approx}1 mm) and temporal ( Greater-Than-Or-Slanted-Equal-To 10 {mu}s) resolution using a thermal supersonic helium jet. A highly accurate detection system is applied to well-developed collisional-radiative model codes to produce the profiles. Agreement between this measurement and an edge Thomson scattering measurement is found to be within the error bars ( Less-Than-Or-Equivalent-To 20%). The diagnostic is being used to give profiles near the ion cyclotron resonant heating antenna on TEXTOR to better understand RF coupling to the core.

Unterberg, E. A.; Fehling, D. H.; Klepper, C. C.; Hillis, D. L. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6169 (United States); Schmitz, O. [Insitut fuer Energieforschung-Plasmaphysik, Forschungszentrum Juelich GmbH, Association EURATOM-FZJ, D-52428 Juelich (Germany); Stoschus, H. [Insitut fuer Energieforschung-Plasmaphysik, Forschungszentrum Juelich GmbH, Association EURATOM-FZJ, D-52428 Juelich (Germany); Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37831-0117 (United States); Munoz-Burgos, J. M. [Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37831-0117 (United States); Van Wassenhove, G. [LPP-ERM/KMS, Association EURATOM-Belgian State, B-1000 Brussels (Belgium)

2012-10-15

168

Contamination levels and spatial distributions of heavy metals and PAHs in surface sediment of Imam Khomeini Port, Persian Gulf, Iran.  

PubMed

Imam Khomeini Port (IKP) is the largest Iranian commercial port. Because of many petrochemical industries and urban areas are located around this port and also having heavy ship traffic, concentrations of PAHs, mercury and other heavy metals were measured as the first time in surface sediment of the jetties. The highest concentrations of PAHs, Hg, Cu, Pb and Fe were recorded at Site 1, located in the vicinity of the petrochemical industrial zone, where ships are repaired. The highest concentration of Zn was found at Site 4, which is the jetty for loading mineral materials. The comparison between measured values in this study and some sediment quality guidelines indicated that the concentrations of mercury and PAHs are much higher than other studies. Also, the ratios of PAHs in the stations showed a mixture of both of pyrolytic and petrogenic sources with a dominance of pyrolytic sources. PMID:23523119

Abdollahi, Sajad; Raoufi, Zeinab; Faghiri, Iraj; Savari, Ahmad; Nikpour, Yadolah; Mansouri, Ali

2013-06-15

169

Comparison of fate profiles of PAHs in soil, sediments and mangrove leaves after oil spills by QSAR and QSPR.  

PubMed

First order removal rates for 15 polyaromatic hydrocarbons (PAHs) in soil, sediments and mangrove leaves were compared in relation to the parameters used in fate transport analyses (i.e., octanol-water partition coefficient, organic carbon-water partition coefficient, solubility, diffusivity in water, HOMO-LUMO gap, molecular size, molecular aspect ratio). The quantitative structure activity relationships (QSAR) and quantitative structure property relationships (QSPR) showed that the rate of disappearance of PAHs is correlated with their diffusivities in water as well as molecular volumes in different media. Strong correlations for the rate of disappearance of PAHs in sediments could not be obtained in relation to most of the parameters evaluated. The analyses showed that the QSAR and QSPR correlations developed for removal rates of PAHs in soils would not be adequate for sediments and plant tissues. PMID:23756470

Tansel, Berrin; Lee, Mengshan; Tansel, Derya Z

2013-08-15

170

ASSESSING RISKS FROM PHOTOACTIVATED TOXICITY OF PAHS TO AQUATIC ORGANISMS  

EPA Science Inventory

Polycyclic aromatic hydrocarbons (PAHs) are one of the most ubiquitous classes of environmental contaminants. Although most PAHs are toxic only at concentrations large enough to cause narcosis, the toxicity of some can be greatly enhanced through mechanisms that involve molecul...

171

Diagnostic accuracy of the urinary albumin: creatinine ratio determined by the CLINITEK Microalbumin and DCA 2000+ for the rule-out of albuminuria in chronic kidney disease  

Microsoft Academic Search

An increased urinary albumin excretion (albuminuria) is an established test for the early detection of renal disease and is also recognized as a risk factor for cardiovascular disease and mortality in a number of clinical settings. There is an established body of data which shows that a random urinary albumin:creatinine ratio (ACR) based on a random urine sample correlates well

Mark Guy; Ronald Newall; Joanna Borzomato; Philip A. Kalra; Christopher Price

2009-01-01

172

Environmental Forensics : Compound Specific Isotope Analysis Of PAHs. Study Of A Former Coal Tar Plant.  

NASA Astrophysics Data System (ADS)

Stable carbon isotopic fingerprints of PAHs obtained by GC-IRMS have often been used in source apportionment studies. The use of PAHs in environmental forensics relies on the assumption that carbon isotopic fractionation caused by microbial degradation is less significant for these heavy molecular weight compounds than for lighter molecules such as chlorinated solvents or BTEX. Carbon isotopic fractionation of PAHs during degradation is still not well understood. The aim of this study was to assess the potential of CSIA of PAHs for environmental forensics applications at a complex (hydrogeology affected by tidal fluxes) former coal tar plant. In this work, soil samples from a tar works site were analyzed. The tar works operated on the site over a period of sixty years. A source apportionment study was first carried out based on 90 target PAHs quantified by GC-MS. These results were then compared to carbon isotope fingerprints. The separation of compounds of interest from co-extracted interfering peaks is a crucial prerequisite of CSIA by GC-IRMS. Hence, a sample preparation method which allowed the determination of precise carbon isotope signatures for up to 35 compounds per soil extract was developed, validated and applied to the samples previously analyzed by GC- MS. Although most soil samples were shown to be related to the point source tar contamination, PAHs ratios and principal component analysis of abundances highlighted some samples with unusual patterns, suggesting the input of a second source of contaminants. However, no statistically significant variation of the isotopic fingerprints of heavy molecular weight PAHs of these samples was observed. This was inconsistent with the first diagnosis. Since evidence was provided that most samples were only affected by a single source of contaminants, carbon isotopic fractionation was investigated in-situ. Importantly, naphthalene and 2- and 1- methylnaphthalenes isotopic fractionation was observed in a vertical soil profile. Results of this study highlight advantages and limitations of CSIA of PAHs in environmental forensics studies and confirm the potential of this technique for deciphering new degradation pathways of lighter PAHs.

Assal, A.; Doherty, R.; Dickson, K.; Kalin, R. M.

2008-12-01

173

Exposure and Kinetics of Polycyclic Aromatic Hydrocarbons (PAHs) in Cigarette Smokers  

PubMed Central

Study objectives were (1) to investigate the selectivity of polycyclic aromatic hydrocarbon (PAH) metabolites for tobacco smoke exposure, and (2) to determine half-lives of PAH metabolites in smokers. There were 622 participants from the United States (US) and Poland, and of these 70% were smokers. All subjects provided spot urine samples and 125 smokers provided blood samples. Urinary PAH metabolite half-lives were determined in 8 smokers. In controlled hospital studies of 18 smokers, the associations between various measures of nicotine intake and urinary excretion of PAH metabolites were investigated. Plasma nicotine was measured by GC. LC-MS/MS was used to measure the plasma levels of cotinine and trans-3?-hydroxycotinine, and urine levels of nicotine and its metabolites, total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and PAH metabolites (2-naphthol, 1-, 2- and 3-hydroxyfluorenes, 1-, 2-, 3-, and 4-hydroxyphenanthrenes, and 1-hydroxypyrene). Regardless of smoking status, PAH metabolite excretion was higher in Polish subjects than in US subjects (p-values<0.001). 1-Hydroxyfluorene exhibited the greatest difference between smokers and non-smokers, with a 5-fold difference in Polish subjects and a 25-fold difference in US subjects, followed by 3- and 2-hydroxyfluorenes, 2-naphthol and 1-hydroxypyrene. The differences for hydroxyphenanthrenes were small or non-significant. 1-Hydroxyfluorene had the highest correlation with urine nicotine equivalents (r=0.77) and urine NNAL (r=0.64). While the half-lives of PAH metabolites were <10 h in smokers, 1-hydroxyfluorene had the largest ratio of initial to terminal urine concentration (58.4±38.6, mean±SD) after smoking. Receiver Operating Characteristic (ROC) analysis of PAHs among Polish and US subjects further showed that hydroxyfluorenes are most highly discriminative of smokers from nonsmokers followed by 2-naphthol and 1-hydroxypyrene. In conclusion, hydroxyfluorenes, particularly 1-hydroxyfluorene, and 2-naphthol are more selective of tobacco smoke than 1-hydroxypyrene and hydroxyphenanthrenes. Characterization of hydroxyfluorene and 2-naphthol metabolites in urine may improve the characterization of PAHs from tobacco smoke and related disease risks among smokers and nonsmokers.

St. Helen, Gideon; Goniewicz, Maciej L.; Dempsey, Delia; Wilson, Margaret; Jacob, Peyton; Benowitz, Neal L

2012-01-01

174

Novel Mutation Identified in the PAH Gene  

Microsoft Academic Search

The investigation of a DNA-amplified fragment of a phenylketonuria (PKU) patient by sequencing reveals a novel mutation in the PAH gene. This mutation represents the deletion of a single base (guanine) localized at the intron 11\\/exon 12 junction. This newly described mutation may be a frameshift or a splicing mutation. The identified mutation expresses phenotypically as the severe form of

E. V. Charikova

1996-01-01

175

PAH EXPOSURES OF NINE PRESCHOOL CHILDREN  

EPA Science Inventory

The exposures to 20 polycyclic aromatic hydrocarbons (PAH) of 9 children, ages 2-5 yr, were measured over 48 hr at day care and at home. Sampled media included indoor and outdoor air, floor dust, outdoor play area soil, hand surface, and solid and liquid food. Urine samples ...

176

Rapid persulfate oxidation predicts PAH bioavailability in soils and sediments  

Microsoft Academic Search

Persulfate oxidation was validated as a method to predict polycyclic aromatic hydrocarbon (PAH) bioavailability in soils and sediments. It was demonstrated for 14 field contaminated soils and sediments that residual PAH concentrations after a short (3 h) persulfate oxidation correspond well to residual PAH concentrations after 21 days of biodegradation. Persulfate oxidation of samples that had first been subjected to

Chiel Cuypers; Tim Grotenhuis; Jan Joziasse; Wim Rulkens

2000-01-01

177

Diurnal and nocturnal measurements of PAH, nitro-PAH, and oxy-PAH compounds in atmospheric particulate matter of a sugar cane burning region  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs, and oxy-PAHs were studied in the atmospheric particulate matter of a subtropical rural region (São Paulo State, Brazil) affected by emissions from sugar cane burning. Diurnal and nocturnal samples were collected from May to June of 2010. In general, average PAH concentrations were significantly higher at night, suggesting that the compounds were predominantly emitted to the atmosphere during biomass burning (which was mainly performed at night). The maximum average PAH concentration was found for benzo[b]fluoranthene at night (2.9 ± 5.4 ng m-3). Among the nitro-PAH compounds, the highest average concentrations were obtained for 9-nitrophenanthrene in diurnal and nocturnal samples (1.5 ± 1.2 and 1.3 ± 2.1 ng m-3, respectively). In contrast to the PAH and nitro-PAH compounds, the oxy-PAHs could not be directly associated with sugar cane burning. The most abundant oxy-PAH compound was benzanthrone (1.6 ± 1.3 ng m-3) at night, followed by 9,10-anthraquinone (1.1 ± 0.9 ng m-3) and 9-fluorenone (0.4 ± 0.1 ng m-3) during the day.

Souza, Kely F.; Carvalho, Lilian R. F.; Allen, Andrew G.; Cardoso, Arnaldo A.

2014-02-01

178

PCB and PAH speciation among particle types in contaminated harbor sediments and effects on PAH bioavailability.  

PubMed

This research provides particle-scale understanding of PCB and PAH distribution in sediments obtained from three urban locations in the United States: Hunters Point, CA; Milwaukee Harbor, WI; and Harbor Point, NY. The sediments comprised mineral grains (primarily sand, silt, and clays) and carbonaceous particles (primarily coal, coke, charcoal, pitch, cenospheres, and wood). The carbonaceous sediment fractions were separated from the mineral fractions based on their lower density and were identified by petrographic analysis. In all three sediments, carbonaceous particles contributed 5-7% of the total mass and 60-90% of the PCBs and PAHs. The production of carbonaceous particles is not known to be associated with PCB contamination, and it is very unlikely that these particles can be the source of PCBs in the environment Thus, it appears that carbonaceous particles preferentially accumulate PCBs acting as sorbents in the aqueous environment if PCBs are released directly to the sediment or if deposited as airborne soot particles. Aerobic bioslurry treatment resulted in negligible PAH loss from the carbonaceous coal-derived material in Milwaukee Harbor sediment but resulted in 80% of the PAHs being removed from carbonaceous particles in Harbor Point sediment. Microscale PAH extraction and analysis revealed that PAHs in Harbor Point sediment were associated mainly with coal tar pitch residue. PAHs present in semisolid coal tar pitch are more bioavailable than PAHs sorbed on carbonaceous particles such as coal, coke, charcoal, and cenosphere. Results of this study illustrate the importance of understanding particle-scale association of hydrophobic organic contaminants for explaining bioavailability differences among sediments. PMID:12785527

Ghosh, Upal; Zimmerman, John R; Luthy, Richard G

2003-05-15

179

Diagnostic usefulness of the random urine Na/K ratio in predicting therapeutic response for diuretics in cirrhotic patients with ascites.  

PubMed

Ascites is a major complication of liver cirrhosis which carries a poor prognosis. Diuretics are used in treatment of ascites in addition to salt restriction. Monitoring of diuretic response can be achieved by measurement of 24 hours urinary sodium. This study evaluated the accuracy of using spot urinary sodium/potassium ratio as a reliable alternative to 24 hours urinary sodium in assessment of dietary sodium compliance in patients with liver cirrhosis receiving diuretics. Fifty patients presented with liver cirrhosis and ascites were divided into 2 groups: GI 14 (28%) patients diuretic resistant with 24 hours urinary sodium < 78 mEq) and GII 36 (72%) patients diuretic sensitive with 24 hours urinary sodium > 78 mEq. The results showed highly significant correlation between 24 hours urinary sodium and spot urine sodium/potassium ratio with sensitivity 87.5% specificity 56% and accuracy 70% at cutoff point of 1.8. PMID:24640876

Mohii, El Sayed M; El Mansy, Ismail M; Salah, Mohamed; Khedr, Mohamed Abd Elhamid

2013-12-01

180

Diagnostic utility of CD4%:CD8(low)% T-lymphocyte ratio to differentiate feline immunodeficiency virus (FIV)-infected from FIV-vaccinated cats.  

PubMed

Antibody testing based on individual risk assessments is recommended to determine feline immunodeficiency virus (FIV) status, but ELISA and Western blot tests cannot distinguish between anti-FIV antibodies produced in response to natural infection and those produced in response to FIV vaccination. The aim of this cross-sectional study was to test the hypothesis that FIV-infected cats could be differentiated from FIV-vaccinated uninfected cats using lymphocyte subset results, specifically the CD4%:CD8(low)% T-lymphocyte ratio. Comparisons of the CD4%:CD8(low)% T-lymphocyte ratio were made among the following four groups: Group 1 - FIV-infected cats (n=61; FIV-antibody positive by ELISA and FIV PCR positive); Group 2 - FIV-uninfected cats (n=96; FIV-antibody negative by ELISA); Group 3 - FIV-vaccinated uninfected cats (n=31; FIV-antibody negative by ELISA before being vaccinated against FIV, after which they tested FIV ELISA positive); and Group 4 - FIV-uninfected but under chronic/active antigenic stimulation (n=16; FIV-antibody negative by ELISA; all had active clinical signs of either upper respiratory tract disease or gingival disease for ? 21 days). The median CD4%:CD8(low)% T-lymphocyte ratio was lower in Group 1 (1.39) than in each of the other three groups (Group 2 - 9.77, Group 3 - 9.72, Group 4 - 5.64; P<0.05). The CD4%:CD8(low)% T-lymphocyte ratio was also the most effective discriminator between FIV-infected cats and the other three groups, and areas under ROC curves ranged from 0.91 (compared with Group 4) to 0.96 (compared with Group 3). CD4%:CD8(low)% shows promise as an effective test to differentiate between FIV-infected cats and FIV-vaccinated uninfected cats. PMID:24559863

Litster, Annette; Lin, Jui-Ming; Nichols, Jamieson; Weng, Hsin-Yi

2014-06-01

181

13CO2/12CO2 ratio analysis in exhaled air by lead-salt tunable diode lasers for noninvasive diagnostics in gastroenterology  

NASA Astrophysics Data System (ADS)

An analyzer of 13CO2/12CO2 ratio in exhaled air based on lead-salt tunable diode lasers is presented. High accuracy of the carbon isotope ratio detection in exhaled carbon dioxide was achieved with help of very simple optical schematics. It was based on the use of MBE laser diodes operating in pulse mode and on recording the resonance CO2 absorption at 4.2 micrometers . Special fast acquisition electronics and software were applied for spectral data collection and processing. Developed laser system was tested in a clinical train aimed to assessment eradication efficiency in therapy of gastritis associated with Helicobacter pylori infection. Data on the 13C-urea breath test used for P.pylori detection and obtained with tunable diode lasers in the course of the trail was compared with the results of Mass-Spectroscopy analysis and histology observations. The analyzer can be used also for 13CO2/12CO2 ratio detection in exhalation to perform gastroenterology breath test based on using other compounds labeled with stable isotopes.

Stepanov, Eugene V.; Zyrianov, Pavel V.; Miliaev, Valerii A.; Selivanov, Yurii G.; Chizhevskii, Eugene G.; Os'kina, Svetlana; Ivashkin, Vladimir T.; Nikitina, Elena I.

1999-07-01

182

Missense mutations in the phenylalanine hydroxylase gene (PAH) can cause accelerated proteolytic turnover of PAH enzyme: A mechanism underlying phenylketonuria  

Microsoft Academic Search

Phenylketonuria (PKU; McKusick 261600) and related forms of hyper- phenylalaninaemia (HPA) are caused by defective activity of the hepatic enzyme phenylalanine hydroxylase (PAH; EC 1.14.16.1). Over 380 alleles of the PAH gene are known, of which over 60% are missense mutations (http:\\/\\/www.mcgill.ca\\/pahdb; Nowacki et al 1998). The question of how a pathogenic PAH missense mutation exerts its eÜects on PAH

P. J. Waters; M. A. Parniak; B. R. Akerman; A. O. Jones; C. R. Scriver

1999-01-01

183

Sources, transport and fate of PAHs in sediments and superficial water of a chronically polluted semi-enclosed body of seawater: linking of compartments.  

PubMed

This paper describes a study of the occurrence, levels and temporal evolution of PAHs in a bay characterized by persistent chronic impacts. A total of 40 samples, 20 of sediment and 20 of water, were taken at each of five different stations, in four sampling campaigns. Analyses of pollutants have been made using GC-MS. Results indicate that in a coastal environment subjected to chronic pollution by pyrolytic PAHs, episodes of petrogenic pollution, like oil-spills, can be identified by the combination of different source ratios. Results also indicate that, in the study area, PAHs are transported from superficial water to sediment. This conclusion is based on the degree of coincidence found in the presence/absence of individual PAHs in both compartments and in their petrogenic/pyrolytic nature, the positive sedimentation rate in the study area, together with the performance of the analyses of unfiltered water and the distribution of sources of PAHs found. PMID:23525235

Rojo-Nieto, Elisa; Sales, Diego; Perales, José Antonio

2013-05-01

184

Comparison of sedimentary PAHs in the rivers of Ammer (Germany) and Liangtan (China): differences between early- and newly-industrialized countries.  

PubMed

As a proxy to trace the impact of anthropogenic activity, sedimentary polycyclic aromatic hydrocarbons (PAHs) are compared between the early industrialized and newly industrialized countries of Germany and China, respectively. Surface sediment samples in the Ammer River of Germany and the Liangtan River of China were collected to compare concentration levels, distribution patterns, and diagnostic plots of sedimentary PAHs. Total concentrations of 16 PAHs in Ammer sediments were significantly higher by a factor of ~4.5 than those in Liangtan. This contrast agrees with an extensive literature survey of PAH levels found in Chinese versus European sediments. Distribution patterns of PAHs were similar across sites in the Ammer River, whereas they were highly varied in the Liangtan River. Pyrogenic sources dominated in both cases. Strong correlations of the sum of 16 PAHs and PAH groups with TOC contents in the Liangtan River may indicate coemission of PAHs and TOC. Poor correlations of PAHs with TOC in the Ammer River indicate that other factors exert stronger influences. Sedimentary PAHs in the Ammer River are primarily attributed to input of diffuse sources or legacy pollution, while sediments in the Liangtan River are probably affected by ongoing point source emissions. Providing further evidence of a more prolonged anthropogenic influence are the elevated black carbon fractions in sedimentary TOC in the Ammer compared to the Liangtan. This implies that the Liangtan River, like others in newly industrialized regions, still has a chance to avoid legacy pollution of sediment which is widespread in the Ammer River and other European waterways. PMID:23252503

Liu, Ying; Beckingham, Barbara; Ruegner, Hermann; Li, Zhe; Ma, Limin; Schwientek, Marc; Xie, Huan; Zhao, Jianfu; Grathwohl, Peter

2013-01-15

185

Sedimentary transport and fate of polycyclic aromatic hydrocarbons (PAH) from managed burning of moorland vegetation on a blanket peat, South Yorkshire, UK.  

PubMed

This study reports the concentrations of 18 polycyclic aromatic hydrocarbons (PAH) from managed burning of moorland vegetation and compares them to PAH in catchment vegetation, underlying peats, head water suspended sediment (HSS), stream water and reservoir sediment cores. Total PAH ranged from 203 to 11,112 ?g/kg in the blanket peats, 101-290 ?g/kg in the fresh moorland vegetation, 4186 ?g/kg at the burnt site, 17,439 ?g/kg in the HSS, 56 ng/L in the stream water and 987 to 7346 ?g/kg in the reservoir sediments. No total or individual PAH concentrations exceeded the published sediment quality guidelines. The perylene content of selected moorland vegetation (sphagnum, heather and bilberry) ranged from 10 to 18% as compared to only 2% for the sediment hosted PAH. A comparison of whole and <250 ?m fractions from the burnt surface layer revealed a near threefold increase in PAH concentration in the fine fraction and a change in the PAH distribution such that naphthalene>phenanthrene>2-methylnaphthalene. Elevated total PAH contents were observed close to the blanket peat sediment surface (0-10 cm) and then declined at greater depths. The high PAH content of the HSS was attributed to the high sorption capacity of the organic-rich particles (TOC 25.8% (wt/wt)). The distribution of individual PAH in reservoir cores and HSS was consistent and the results of the principal component analysis and isomeric ratios suggest mainly pyrolytic inputs, from either vegetation burning and coal combustion. A comparison of the reservoir core PAH profiles shows that the source(s) have remained largely unchanged since the reservoir construction in 1929A.D. reflecting consistent moorland management practices. PMID:23416203

Vane, Christopher H; Rawlins, Barry G; Kim, Alexander W; Moss-Hayes, Vicky; Kendrick, Christopher P; Leng, Melanie J

2013-04-01

186

Are urinary PAHs biomarkers of controlled exposure to diesel exhaust?  

PubMed

Abstract Urinary polycyclic aromatic hydrocarbons (PAHs) were evaluated as possible biomarkers of exposure to diesel exhaust (DE) in two controlled-chamber studies. We report levels of 14 PAHs from 28 subjects in urine that were collected before, immediately after and the morning after exposure. Using linear mixed-effects models, we tested for effects of DE exposure and several covariates (time, age, gender and urinary creatinine) on urinary PAH levels. DE exposures did not significantly alter urinary PAH levels. We conclude that urinary PAHs are not promising biomarkers of short-term exposures to DE in the range of 106-276?µg/m(3). PMID:24754404

Lu, Sixin S; Sobus, Jon R; Sallsten, Gerd; Albin, Maria; Pleil, Joachim D; Gudmundsson, Anders; Madden, Michael C; Strandberg, Bo; Wierzbicka, Aneta; Rappaport, Stephen M

2014-06-01

187

Polycyclic aromatic hydrocarbon (PAH) ecotoxicology in marine ecosystems.  

PubMed

Low levels of oil and hence polycyclic aromatic hydrocarbons (PAHs) are naturally present in the marine environment, although levels have increased significantly following human extraction and use of oil and gas. Other major anthropogenic sources of PAHs include smelters, the use of fossil fuels in general, and various methods of waste disposal, especially incineration. There are two major sources for PAHs to marine ecosystems in Norway: the inshore smelter industry, and offshore oil and gas production activities. A distinction is generally made between petrogenic (oil-derived) and pyrogenic (combustion-derived) PAHs. Although petrogenic PAHs appear to be bioavailable to a large extent, pyrogenic PAHs are often associated with soot particles and less available for uptake into organisms. There is extensive evidence linking sediment-associated PAHs to induction of phase-I enzymes, development of DNA adducts, and eventually neoplastic lesions in fish. Most studies have focused on high-molecular-weight, carcinogenic PAHs such as benzo[a]pyrene. It is less clear how two- and three-ring PAHs affect fish, and there is even experimental evidence to indicate that these chemicals may inhibit some components of the phase I system rather than produce induction. There is a need for increased research efforts to clarify biological effects of two- and three-ring PAHs, PAH mixtures, and adaptation processes in marine ecosystems. PMID:16291565

Hylland, Ketil

2006-01-01

188

Polycyclic aromatic hydrocarbon (PAH) emissions from charcoal grilling  

NASA Astrophysics Data System (ADS)

The emission of polycyclic aromatic hydrocarbons (PAH) was quantitated in the smoke from the grilling of meat using hardwood charcoal as fuel in a table grill set. Smoke samples were collected with an ice-cooled condenser and subsequently cleaned up employing both open column- and high performance-liquid chromatography techniques. Using a PAH standard mixture, 23 PAH were identified in the smoke using gas chromatography-mass spectrometry. Emission levels of PAH ranged from several tens of ?g kg -1 meat for some 3- and 4-ringed PAH, to sub ?g kg -1 meat levels for the 5- and 6-ringed PAH (sum of PAH approximately 0.1 mg kg -1 meat), originating from a 10 min grilling of 0.33 kg minced lean pork. The major source of PAH emitted to the local air environment from charcoal grilling is from the combustion of the charcoal itself. The amount of PAH emitted from charcoal grilling in Sweden, time period June to August, is estimated to approximately 2 kg which is a minor source to the total emissions of PAH to the environment. However, relatively large peak exposures of PAH can be expected in a more local environment, e.g. during household grilling.

Dyremark, Anders; Westerholm, Roger; Övervik, Eva; Gustavsson, Jan-Åke

189

Usefulness of the organ culture system when villous height/crypt depth ratio, intraepithelial lymphocyte count, or serum antibody tests are not diagnostic for celiac disease.  

PubMed

The existence of mild forms of celiac disease (CD) can make the histology-based diagnosis difficult to reach. Since anti-endomysium (EMA) and anti-tissue transglutaminase (anti-tTG) are detectable in culture supernatants of duodenal biopsies from CD patients, our aim was to assess if this system can support the histology in the diagnostic work-up. A total of 559 suspected CD patients underwent serum EMA/anti-tTG detection, upper endoscopy with duodenal biopsy sampling, histologic analysis, and organ culture to detect EMA/anti-tTG in supernatants. A subgroup of 30 patients with organ culture positive results were put on a gluten-free diet (GFD). Their gluten-dependency was evaluated by the psychological general well-being and beck depression inventory indexes. Statistical analysis was performed by Cohen k inter-test, Friedman test, and Dunn multiple comparison. Two hundred forty-one out of 559 (43.1%) patients showed intestinal villous atrophy, whereas serum and organ culture EMA/anti-tTG were positive in 293/559 (52.4%) and 334/559 (59.7%) patients, respectively. The strength of agreement resulted good for serology vs histology (k = 0.730), good for organ culture vs histology (k = 0.662), and very good for serology vs organ culture (k = 0.852). After 12 months of GFD, psychological general well-being index significantly increased, and beck depression inventory index significantly decreased (P < 0.001 for each one). Data highlight the organ culture system as a useful tool to assist the histology in diagnosing CD, mainly in cases without villous atrophy or in seronegative patients. The marked improvement in quality of life after a GFD further supports the reliability of this system in diagnosing CD. PMID:23177794

Picarelli, Antonio; Di Tola, Marco; Marino, Mariacatia; Libanori, Valerio; Borghini, Raffaele; Salvi, Elisa; Donato, Giuseppe; Vitolo, Domenico; Tiberti, Antonio; Marcheggiano, Adriana; Bassotti, Gabrio; Corazziari, Enrico

2013-03-01

190

Urinary 1-hydroxypyrene, a PAH biomarker in foundry workers.  

PubMed

Exposure to PAH in foundry workers has been studied by urinary 1-hydroxypyrene (HPU) levels, quantitatively measured by reversed phase HPLC. Seventy male foundry workers and 68 matched controls were investigated. Polycyclic aromatic hydrocarbon (PAH) exposure was defined by 17 breathing zone hygienic samples, consisting of 16 selected PAH compounds. Mean total PAH concentration (SD) was 10.40 (4.04) mu g/m3. A multiple regression model of tobacco consumption, age, airborne PAH-exposure and foundry work on log HPU showed a significant correlation, p < 0.001, r2 = 0.69. Only foundry work (p < 0.0001) and airborne PAH exposure (p = 0.0478) contributed significantly to the model. These data suggest that HPU is a sensitive biomarker for low-dose PAH exposure. PMID:8907204

Omland, O; Sherson, D; Hansen, A M; Sigsgaard, T; Autrup, H; Overgaard, E

1996-01-01

191

Rapid persulfate oxidation predicts PAH bioavailability in soils and sediments  

SciTech Connect

Persulfate oxidation was validated as a method to predict polycyclic aromatic hydrocarbon (PAH) bioavailability in soils and sediments. It was demonstrated for 14 field contaminated soils and sediments that residual PAH concentrations after a short (3 h) persulfate oxidation correspond well to residual PAH concentrations after 21 days of biodegradation. Persulfate oxidation of samples that had first been subjected to biodegradation yielded only limited additional PAH oxidation. This implies that oxidation and biodegradation removed approximately the same PAH fraction. Persulfate oxidation thus provides a good and rapid method for the prediction of PAH bioavailability. Thermogravimetric analysis of oxidized and untreated samples showed that persulfate oxidation primarily affected expanded organic matter. The results indicate that this expanded organic matter contained mainly readily bioavailable PAHs.

Cuypers, C.; Grotenhuis, T.; Joziasse, J.; Rulkens, W.

2000-05-15

192

PAHs, nitro-PAHs, hopanes, and steranes in lake trout from Lake Michigan.  

PubMed

The present study examines concentrations and risks of polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs (NPAHs), steranes, and hopanes in lake trout collected in Lake Michigan. A total of 74 fish were collected in 2 seasons at 3 offshore sites. The total PAH concentration (?9 PAH) in whole fish ranged from 223?pg/g to 1704?pg/g wet weight, and PAH concentrations and profiles were similar across season, site, and sex. The total NPAH (?9 NPAH) concentrations ranged from 0.2?pg/g to 31?pg/g wet weight, and carcinogenic compounds, including 1-nitropyrene and 6-nitrochrysene, were detected. In the fall, NPAH concentrations were low at the Illinois site (0.2-0.5?pg/g wet wt), and site profiles differed considerably; in the spring, concentrations and profiles were similar across sites, possibly reflecting changes in fish behavior. In the fall, the total sterane (?5 Sterane) and total hopane (?2 Hopane) levels reached 808?pg/g and 141?pg/g wet weight, respectively, but concentrations in the spring were 10 times lower. Concentrations in eggs (fall only) were on the same order of magnitude as those in whole fish. These results demonstrate the presence of target semivolatile organic compounds in a top predator fish, and are consistent with PAH biodilution observed previously. Using the available toxicity information for PAHs and NPAHs, the expected cancer risk from consumption of lake trout sampled are low. However, NPAHs contributed a significant portion of the toxic equivalencies in some samples. The present study provides the first measurements of NPAHs in freshwater fish, and results suggest that additional assessment is warranted. Environ Toxicol Chem 2014;33:1792-1801. © 2014 SETAC. PMID:24764175

Huang, Lei; Chernyak, Sergei M; Batterman, Stuart A

2014-08-01

193

Superhydrogenated PAHs: Catalytic formation of H2  

NASA Astrophysics Data System (ADS)

The possible role of neutral PAHs as catalysts for H2 formation in the interstellar medium is investigated by a combined experimental and density function theory study of the superhydrogenation of coronene (C24H12). The calculations suggest efficient hydrogenation of both edge and centre sites, along with competing abstraction reactions to form H2 in a series of catalytic cycles. Scanning tunneling microscopy and thermal desorption measurements have been used to provide direct evidence of the formation of superhydrogenated coronene as a result of exposure to D atoms. Lower limit estimates for the cross-sections of 1.8 × 10-17, 5.5 × 10-18 and 1.1 × 10-18 cm2 for the formation of singly, doubly and triply hydrogenated coronene are derived. The results suggest that superhydrogenated PAHs may play an important role in H2 formation in the ISM.

Thrower, J. D.; Nilsson, L.; Jørgensen, B.; Baouche, S.; Balog, R.; Luntz, A. C.; Stensgaard, I.; Rauls, E.; Hornekær, L.

2011-03-01

194

Heterogeneous oxidation and photochemistry of PAHs  

NASA Astrophysics Data System (ADS)

Until recently, the atmospheric degradation of polycyclic aromatic hydrocarbons (PAHs) was thought to occur primarily via gas phase reaction with OH or NO3. We have measured the heterogeneous oxidation kinetics of naphthalene, anthracene, fluoranthene, phenanthrene, pyrene, and benzo[a]pyrene sorbed on an "urban grime" substrate with gas phase ozone over a wide range of ozone concentrations. Including these kinetics in mass- balance models shows that they may be very important in establishing the fate of PAHs in urban environments. The photolysis rates of anthracene and naphthalene at the air-ice interface were measured, and the kinetics were compared to those observed in water solution and at the air-water interface. Reaction at the ice surface is 4-6 X faster than at the water surface, probably due to an enhancement in the absorption cross sections and/or photolysis quantum yields.

Donaldson, D.; Kahan, T. F.; Kwamena, N. A.

2007-05-01

195

[PAH Cations as Viable Carriers of DIBs  

NASA Technical Reports Server (NTRS)

This report is intended to fill in the blanks in NASA's file system for our lab astro study of molecular ions of astrophysical interest. In order to give NASA what it needs for its files, I attach below the text of the section from our recent proposal to continue this work, in which we describe progress to date, including a large number of publications. Our initial studies were focused on PAH cations, which appear to be viable candidates as the carriers of the DIBs, an idea that has been supported by laboratory spectroscopy of PAH cations in inert matrices. Beginning with the simplest aromatic (benzene; C6H6) and moving progressively to larger species (naphthalene, C10OH8; pyrene, C16H10; and most recently chrysene, C18H12), we have been able to derive rate coefficients for reactions with neutral spices that are abundant in the diffuse interstellar medium.

Snow, Ted

1998-01-01

196

Isomer distributions of molecular weight 247 and 273 nitro-PAHs in ambient samples, NIST diesel SRM, and from radical-initiated chamber reactions  

NASA Astrophysics Data System (ADS)

Molecular weight (mw) 247 nitrofluoranthenes and nitropyrenes and mw 273 nitrotriphenylenes (NTPs), nitrobenz[a]anthracenes, and nitrochrysenes were quantified in ambient particles collected in Riverside, CA, Tokyo, Japan, and Mexico City, Mexico. 2-Nitrofluoranthene (2-NFL) was the most abundant nitro-polycyclic aromatic hydrocarbon (nitro-PAH) in Riverside and Mexico City, and the mw 273 nitro-PAHs were observed in lower concentrations. However, in Tokyo concentrations of 1- + 2-NTP were more similar to that of 2-NFL. NIST SRM 1975 diesel extract standard reference material was also analyzed to examine nitro-PAH isomer distributions, and 12-nitrobenz[a]anthracene was identified for the first time. The atmospheric formation pathways of nitro-PAHs were studied from chamber reactions of fluoranthene, pyrene, triphenylene, benz[a]anthracene, and chrysene with OH and NO3 radicals at room temperature and atmospheric pressure, with the PAH concentrations being controlled by their vapor pressures. Sampling media were spiked with deuterated PAH to examine heterogeneous nitration. Comparing specific nitro-PAH ratios in ambient and diesel particles with those from our chamber experiments suggests that the low 2-NFL/NTPs ratios in Tokyo particulate matter are not a result of gas-phase radical-initiated chemistry since both gas-phase OH and NO3 radical-initiated reactions result in high 2-NFL/NTPs ratios. Comparisons of the relative formation of deuterated nitro-PAHs on the sampling media suggest that heterogeneous reactions with N2O5 on ambient particle surfaces also do not explain the nitro-PAH profiles of Tokyo particles. Thus, the source of NTPs in Tokyo remains unidentified.

Zimmermann, Kathryn; Atkinson, Roger; Arey, Janet; Kojima, Yuki; Inazu, Koji

2012-08-01

197

A novel approach to investigating indoor/outdoor pollution links: Combined magnetic and PAH measurements  

NASA Astrophysics Data System (ADS)

In a preliminary study, paired indoor and outdoor air sampling was conducted at three locations around the city of Lancaster, UK to examine the influence of combustion sources on air quality by measuring particulate concentrations, particulate magnetic properties and polyaromatic hydrocarbons (PAHs). With one exception (an indoor suburban air sample), outdoor air samples had higher total suspended particulates (TSP), particle-bound PAH concentrations and magnetic remanence (IRM) values. IRM values were highest for the week-day, outdoor city centre samples and then declined in the sequence: Sunday, city centre > suburban/residential > Lancaster University campus. These data indicate traffic as the major particle-bound PAH, particulates and magnetic source, particularly as sampling was conducted during July in the absence of any space heating. The indoor air samples revealed a wide variation in pollutant concentrations, characterised by higher vapour levels of 2-3 ring PAHs, variable TSP concentrations and variable but generally low IRMs. The differences in PAH concentrations, TSP and IRMs between outdoor and indoor environments indicate limited ingress of outdoor air pollutants to the indoor environment in this study. Our combined PAH and magnetic data identify specific and distinctive indoor pollution signals for each of our sampled sites, reflecting distinct sources. One site, the suburban house, has anomalously high IRM, TSP and particle-bound PAHs. A possible source for these is a cast-iron, wood-burning stove (even though not lit). The city centre indoor site is characterised by high TSP and very low IRMs but high values of the magnetic ratio of anhysteretic remanence:saturation remanence, indicative of ultrafine (sub-micrometre) magnetic grain sizes. The source for this city centre indoor signature is unidentified but may reflect the occupant smoking and/or lighting candles. The indoor campus sample was affected by loss-on-ignition procedures carried out in a teaching laboratory. The combined PAH and magnetic analyses thus provide a sensitive and discriminatory means of identifying outdoor, traffic-derived pollution, and of discriminating between different types of indoor pollution.

Halsall, C. J.; Maher, B. A.; Karloukovski, V. V.; Shah, P.; Watkins, S. J.

198

Determination of PAHs and OH-PAHs in rat brain by gas chromatography tandem (triple quadrupole) mass spectrometry.  

PubMed

An efficient and selective method for the quantitative determination of polycyclic aromatic hydrocarbons (PAHs) and their monohydroxylated metabolites (OH-PAHs) in rat brain tissue using gas chromatography tandem (triple quadrupole) mass spectrometry (GC-MS/MS) was developed and validated. The list of molecules investigated comprised the 16 PAHs from the US-EPA list and 53 of their OH-PAHs. Brain extract was submitted to enzymatic hydrolysis, followed by liquid-liquid extraction, and then purified by solid-phase extraction. Limits of quantification ranged from 0.6 to 29 pg/mg and from 0.5 to 30 pg/mg for PAHs and OH-PAHs respectively. The analysis of rat brain samples exposed to PAH mixture (0.01-1 mg/kg, 28 days, ip) demonstrated that this method allowed the detection of 16 PAHs and 28 OH-PAHs out of the 69 analytes investigated. Mean concentrations of PAHs in animal brain samples exposed to 1 mg/kg of PAH mixture ranged from 3.0 ± 2 pg/mg for benzo[b]fluoranthene to 146 ± 29 pg/mg for phenanthrene. Concomitantly, mean concentrations of OH-PAHs ranged from 0.49 ± 0.4 to 26.5 ± 23 pg/mg for 2-OH-chrysene and 1-OH-pyrene respectively. This study proves, for the first time, the bioavailability of most of the PAHs and OH-PAHs in mammalian brain tissue and should provide an important new tool for future neurotoxicological studies. PMID:21916506

Grova, Nathalie; Salquèbre, Guillaume; Schroeder, Henri; Appenzeller, Brice M R

2011-10-17

199

Migration of polycyclic aromatic hydrocarbons (PAHs) in urban treatment sludge to the air during PAH removal applications.  

PubMed

In the present study, the amounts of polycylic aromatic hydrocarbons (PAHs) penetrating into air during PAH removal applications from the urban treatment sludge were investigated. The effects of the temperature, photocatalyst type, and dose on the PAH removal efficiencies and PAH evaporation were explained. The sludge samples were taken from an urban wastewater treatment plant located in the city of Bursa, with 585,000 equivalent population. The ultraviolet C (UV-C) light of 254 nm wavelength was used within the UV applications performed on a specially designed setup. Internal air of the setup was vacuumed through polyurethane foam (PUF) columns in order to collect the evaporated PAHs from the sludge during the PAH removal applications. All experiments were performed with three repetitions. The PAH concentrations were measured by gas chromatography-mass spectrometry (GC-MS). It was observed that the amounts of PAHs penetrating into the air were increased with increase of temperature, and more than 80% of PAHs migrated to the air consisted of 3-ring compounds during the UV and UV-diethylamine (DEA) experiments at 38 and 53 degrees C. It was determined that 40% decrease was ensured in sigma12 (total of 12) PAH amounts with UV application and 13% of PAHs in sludge penetrated into the air. In the UV-TiO2 applications, a maximum 80% of sigma12 PAH removal was obtained by adding 0.5% TiO2 of dry weight of sludge. The quantity of PAH penetrating into air did not exceed 15%. UV-TiO2 applications ensured high levels of PAH removal in the sludge and also reduced the quantity of PAH penetrating into the air. Within the scope of the samples added with DEA, there was no increase in PAH removal efficiencies and the penetration of PAHs into air was not decreased. In light of these data, it was concluded that UV-TiO2 application is the most suitable PAH removal alternative that restricts the convection of PAH pollution. PMID:24941705

Karaca, Gizem; Cindoruk, S Siddik; Tasdemir, Yücel

2014-05-01

200

Diagnostic Development on NSTX  

SciTech Connect

Diagnostics are described which are currently installed or under active development for the newly commissioned NSTX device. The low aspect ratio (R/a less than or equal to 1.3) and low toroidal field (0.1-0.3T) used in this device dictate adaptations in many standard diagnostic techniques. Technical summaries of each diagnostic are given, and adaptations, where significant, are highlighted.

A.L. Roquemore; D. Johnson; R. Kaita; et al

1999-12-16

201

Integrated helmet system for PAH2/AVT  

NASA Astrophysics Data System (ADS)

The German Government selected Eurocopter Deutschland (ECD) to coordinate the development of a new 40 degree(s) Integrated Helmet System (IHS) for the PAH2 (Panzer Abwehr Hubschrauber 2. Gen) helicopter. ECD were tasked with integrating the IHS into the BK117/AVT (Ausrustungs-Versuchs-Trager) for flight trials. A contract was placed in 1992 with GEC-Marconi Avionics of the UK for the IHS. This IHS consists of a new light weight helmet shell equipped with an individual form fit liner, intercom and a removable Optical Module which includes two Cathode Ray Tubes (CRT), two Image Intensifier Tubes (I2T), two see-through combiners and a Helmet Mounted Sight (HMS) Receiver. An A- model helmet with a 35 degree(s) Field of View (FOV) was tested on the BK117-AVT, with flight symbology during Nap of the Earth flights in early 1994. A similar helmet was assessed during 1990/91 on a PAH1 in Celle. In this version, no HMS was installed in the HC. An A/B-model helmet (a B-model helmet with an A-model electronics) with 40 degree(s) FOV was received at the end of 1994 and tested in the ECD Visionics laboratory. The flight trials started on a PAH1 in Manching January 1995 and in the new moon phase of February/March 1995 in Buckeburg. The wearing comfort of the helmet and the night channel were evaluated. The new IHS has been specially designed for PAH2. In C-model configuration the IHS shall have a total helmet weight of 2.2 kg, an optimized Centre of Gravity, exit pupils with > 15 mm, IITs with > 50 Lp/mm and gain in excess of 2000, CRTS with high resolution and high brightness for daytime application. There is a requirement for the HMS to have an accuracy of 0.2 degree(s) in a large Head Motion Box. This HMS steers a nose mounted FLIR platform and has the task of aiming precise weapon systems on targets. The paper presents the results of IHS assessment in the laboratory and flight trial assessments with the IHS on a PAH1.

Boehm, Hans-Dieter V.; Behrmann, Peter; Stenner, K.-H.

1995-05-01

202

Sorption and chemical transformation of PAHs on coal fly ash  

SciTech Connect

The objective of this research is to characterize the interactions of coal fly ash with polycyclic aromatic hydrocarbons (PAHs) and their derivatives, and to understand the influence of the surface properties of coal ash (and other atmospheric particles) on the chemical transformations of polycyclic aromatic compounds. Studies to be carried out in this project include: (1) Fractionation of heterogeneous coal fly ash samples into different particle types varying in size and chemical composition (carbonaceous, mineral-magnetic, and mineral nonmagnetic); (2) Measurement of the rates of chemical transformation of PAHs and PAH derivatives (especially nitro-PAHs) and the manner in which the rates of such processes are influenced by the chemical and physical properties of coal fly ash particles; (3) Chromatographic and spectroscopic studies of the nature of the interactions of coal fly ash particles with PAHs and PAH derivatives; (4) Characterization of the fractal nature of fly ash particles (via surface area measurements) and the relationships of surface roughness'' of fly ash particles to the chemical behavior of PAHs sorbed on coal ash particles; (5) Identification of the major products of chemical transformation of PAHs on coal ash particles, and examination of any effects that may exist of the nature of the coal ash surface on the identities of PAH transformation products; and (6) Studies of the influence of other sorbed species on the chemical behavior of PAHs and PAH derivatives on fly ash surfaces. PAHs are deposited, under controlled laboratory conditions, onto coal ash surfaces from the vapor phase, in order to mimic the processes by which PAHs are deposited onto particulate matter in the atmosphere.

Mamantov, G.; Wehry, E.L.

1991-01-01

203

Black Carbon and Sorption of PAHs in Natural Fire-Impacted Sediments From Oriole Lake (CA)  

NASA Astrophysics Data System (ADS)

We investigated the occurrence of black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs) in sediment samples from Oriole Lake (Kings Canyon and Sequoia National Park, California). Sequoia National Park provided a unique environment for this study, as its frequent natural fires are recorded in the giant Sequoias. From the tree record the fire record for the past ~ 500 years is known. Having this fire recorded provides a unique opportunity to reference the sediment layers to a known fire chronology. Ca. 4 m of sediment covering the last 5,000 years were taken in July 2007 at Oriole Lake. Cores were sliced into 1 cm increments, and analyzed for 210Pb and 137Cs for dating. Samples were extracted for PAH and analyzed for organic C and BC, according to a method by Gustafsson et al. (1997). Highest BC concentrations (> 0.5% d.w.) in the last century correlated with individual forest fire events in the region. Long-range transport of traffic emissions might have contributed to a gently rising baseline of sedimentary BC concentrations. PAH ratios (e.g., methylphenanthrenes versus phenanthrenes) indicated a prevalence of pyrogenic emissions. Sediments from the last 20 years were incubated with passive PE samplers to derive porewater concentrations. Results are used to discern whether the char-rich sediments display a stronger sorption of PAHs than can be explained by the combined OC and BC pools.

Sullivan, J.; Lohmann, R.; Bollinger, K. A.; King, J.; Cantwell, M.; Caprio, T.

2008-12-01

204

A Novel Approach to the Detection and Characterization of PAH Cations and PAH-Photoproducts  

NASA Astrophysics Data System (ADS)

Cationic polycyclic aromatic hydrocarbons (PAHs) are attractive candidates for the Diffuse Interstellar Bands, but to date not a single PAH species has been identified on the basis of a spectral agreement. This indicates either that the molecular diversity is very large or that the candidates that have been considered are not the correct ones. In particular, small/medium-sized PAH cations are submitted to photodissociation under UV photons from stars. Therefore it is of interest to characterize the spectroscopic properties of key breakdown products. Furthermore, these studies should be performed under conditions that mimic those found in interstellar space, which leads to additional experimental difficulties. We describe the approach we are developing with the PIRENEA set-up and present results on the 1-Methylpyrene cation and photo-derived species. Experimental measurements are guided by calculations based on density functional theory.

Kokkin, D. L.; Simon, A.; Marshall, C.; Bonnamy, A.; Joblin, C.

2014-02-01

205

YEAR TIME MODULATION OF n-ALKANES, PAH, NITRO-PAH AND ORGANIC ACIDS AT MONTELIBRETTI ROME, ITALY  

Microsoft Academic Search

The organic fraction of airborne particulates was investigated at Montelibretti RM, Italy, over 12 months and n-alkanes, polycyclic aromatic hydrocarbons, nitrated polycyclic aromatics and aliphatic acids were evaluated. The year time modulations were acquired from all groups of compounds, both in quantitative (cumulative concentrations) and qualitative (percent compositions) terms. Some distribution indexes and diagnostic ratio rates drawn from congener abundances

A. Cecinato; C. Balducci; G. Nervegna; S. Pareti; G. Tagliacozzo; A. Brachetti

2008-01-01

206

Formation of genotoxic nitro-PAH compounds in fish exposed to ambient nitrite and PAH.  

PubMed

Mutagenic nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) have been known to arise in the environment through direct emissions from combustion sources and nitration of PAHs, primarily in the atmosphere. Here, we report the formation of nitro-PAH compounds in fish contaminated with PAH and exposed to nitrite (NO2-) in the ambient water. Electrospray ionization mass spectrometric analysis of the bile of the euryhaline fish Oreochromis mossambicus exposed simultaneously to field-relevant, sublethal concentrations of phenanthrene (1 microg/g) and NO2- (1 microM) and collision-induced dissociation of selected ions revealed the presence of two strongly genotoxic nitro-PAH metabolites, namely phenanthrene-6-nitro-1,2-dihydrodiol-3,4-epoxide (mass/charge [m/z] 273) and dihydrodihydroxy acetylamino nitrophenanthrene (m/z 359). These two metabolite peaks present only in the bile of fish exposed simultaneously to phenanthrene and NO2- constituted, respectively, about 3.1 and 2.7% of the highest peak among the putative unconjugated phenanthrene metabolites in the mass spectrum. The presence of the oxidized phenanthrene metabolite dihydroxyphenanthrene (m/z 233) in fish exposed to phenanthrene alone as well as phenanthrene plus NO2- suggested that oxidation of phenanthrene precedes nitration in the sequence of reactions leading to the formation of the observed nitrophenanthrene metabolites. However, the route of PAH administration seems to determine the nature of metabolites formed. Nearly 92% of the hepatic cells of the fish exposed to phenanthrene in the presence of NO2- were found to have suffered extensive DNA fragmentation on comet assay. PMID:16531469

Shailaja, M S; Rajamanickam, Rani; Wahidulla, Solimabi

2006-06-01

207

Grafted cellulose for PAHs removal present in industrial discharge waters  

NASA Astrophysics Data System (ADS)

Keywords: cellulose; biosorbent; PAHs; polycontaminated wastewaters; trace levels. Polycyclic aromatic hydrocarbons (PAHs), chemicals essentially formed during incomplete combustion of organic materials from anthropogenic activities, were present in all compartments of the ecosystem, air, water and soil. Notably, a part of PAHs found in aquatic system was introduced through industrial discharge waters. Since the Water Framework Directive has classified certain PAHs as priority hazardous substances, industrials are called to take account this kind of organic pollutants in their global environmental concern. Conventional materials such as activated carbons definitively proved their worth as finishing treatment systems but remained costly. In this study, we proposed to use cellulose grafted with glycidyl methacrylate [1] for the removal of PAHs present in discharge waters of surface treatment industries. Firstly, to develop the device, we worked with synthetic solutions containing 16 PAHs at 500 ng/L. Two types of grafted cellulose were tested over a closed-loop column with a concentration of 4g cellulose/L: cellulose C2 with a hydroxide group and cellulose C4 with an amine group. No PAH was retained by the raw cellulose whereas abatement percentages of PAHs were similar between C2 and C4 (94% and 98%, respectively, for the sum of the 16 PAHs) with an experiment duration of 400 min (corresponding to about 20 cycles through grafted cellulose). Secondly, to determine the shorter time to abate the amount maximum of PAHs through the system, a kinetic was realized from 20 min (one cycle) to 400 min with C4. The steady state (corresponding to about 95% of abatement of the total PAHs) was reached at 160 min. Finally, the system was then tested with real industrial discharge waters containing both mineral and organic compounds. The results indicated that the abatement percentage of PAHs was similar between C2 and C4, corroborating the tests with synthetic solution. In return, the grafted cellulose showed lower adsorption capacities of PAHs (about 40% for the total PAH content) when they were in real effluents than they were in synthetic solutions. However, it was observed that PAH composition in discharge waters was different than in synthetic solutions, qualitatively and quantitatively. Despite the presence of numerous other substances in industrial effluents at high concentrations (for instance metals equal to mg/L and salts to g/L), the grafted cellulose was demonstrated as suitable to remove organic substances at trace levels like PAHs (equal to ng/L). Reference: [1] Vismara E., Melone L., Gastaldi G., Cosentino C., Torri G. J. Hazardous Mat. 170 (2009) 798-808. Acknowledgements: The authors thank Agence de l'Eau, FEDER and the Conseil regional de Franche-Comté for financial support (NIRHOFEX Program).

Euvrard, Elise; Druart, Coline; Poupeney, Amandine; Crini, Nadia; Vismara, Elena; Lanza, Tommaso; Torri, Giangiacomo; Gavoille, Sophie; Crini, Gregorio

2014-05-01

208

Analysis of the effect of tetrahydrobiopterin on PAH gene expression in hepatoma cells  

Microsoft Academic Search

Tetrahydrobiopterin (BH4)-responsive phenylalanine hydroxylase (PAH) deficiency is a recently recognized variant of phenylketonuria, with a probable multifactorial molecular basis. In this study we have investigated the effect of BH4 on PAH gene expression in human hepatoma. Our results show that increased BH4 levels result in an enhancement of PAH activity and PAH protein, due to longer turnover rates, while PAH

Cristina Aguado; Belén Pérez; Magdalena Ugarte; Lourdes R. Desviat

2006-01-01

209

PCBs, PBDEs, and PAHs in Toronto air: spatial and seasonal trends and implications for contaminant transport.  

PubMed

The distributions of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs) in the atmosphere of Toronto, Canada and the surrounding suburban/rural area were examined. A series of temporally- and spatially-distributed air samples was collected over a 1-year period with a high-volume active air sampler at one downtown site and polyurethane foam passive air samplers at 19 sites. Passive sampler air concentrations of ?PAHs ranged from 0.27 to 51 ng/m³. Concentrations of ?PCBs ranged from 6.0 to 1300 pg/m³, and concentrations of ?PBDEs ranged from 0.47 to 110 pg/m³. All compounds exhibited the highest concentrations in the urban core, and lowest concentrations in the surrounding rural areas, however the exact ratio depended on location since concentrations varied considerably within the city. Results from the application of a radial dilution model highlighted the influence of the central business district (CBD) of the city as a source of contaminants to the surrounding environment, however the radial dilution comparison also demonstrated that sources outside the CBD have a significant influence on regional contaminant concentrations. A strong relationship between temperature and partial pressure of the gas-phase PCBs, low molecular weight PBDEs and less-reactive PAHs suggested that their dominant emissions originated from temperature-controlled processes such as volatilization from local sources of PCBs, PAHs and PBDEs at warm temperatures, condensation and deposition of emissions at cold temperatures, and ventilation of indoor air with elevated concentrations. The relationship between temperature and atmospheric PAH concentrations varied along the urban-rural gradient, which suggested that in highly urbanized areas, such as downtown Toronto, temperature-related processes have a significant impact on air concentrations, whereas winter emissions from domestic heating have a greater influence in areas with less impervious surface coverage. PMID:22578845

Melymuk, Lisa; Robson, Matthew; Helm, Paul A; Diamond, Miriam L

2012-07-01

210

Modelling the behaviour of PAHs during atmospheric transport from the UK to the Arctic  

NASA Astrophysics Data System (ADS)

Persistent organic pollutants (POPs) such as PAHs are subject to long-range atmospheric transport, which can result in the contamination of remote areas such as the Arctic. A simple model was developed to describe the removal processes of four PAHs; fluorene (FLU), phenanthrene (PHEN), fluoranthene (FLA) and benzo[a]pyrene (B[a]P) transported over a 5 day period from a source area over the UK to the Russian Arctic. The purpose of this model was to study processes affecting the PAHs within the atmosphere, rather than their interaction with the earth's surface. The components to the model included gas/particle partitioning, reaction with OH radicals and dry and wet deposition (both rain and snow). Atmospheric/meteorological parameters for the geographical region of interest were generated from three-dimensional atmospheric models. Air concentrations were prescribed in the source area with no additional PAH inputs along the transect, both winter and summer scenarios were modelled. Reaction with OH was a major removal mechanism for gas-phase FLU, PHEN and FLA, most notably in the temperate atmosphere. Wet deposition in the form of snow accounted for the majority of PAH loss in the winter, although the gas and particle scavenging ratios used in this model ranged over several orders of magnitude. Using a 5 day transport scenario in a `1-hop' event, the model predicted that a primary emission of FLA and B[a]P to the atmosphere of the southern UK, would not reach the Russian Arctic at a distance of ˜3500 km, assuming a constant windspeed of 10 m s -1. However, both FLU and PHEN with calculated half-lives of >60 h during the winter could be transported to this area under this scenario.

Halsall, C. J.; Sweetman, A. J.; Barrie, L. A.; Jones, K. C.

211

PAH emission from Nova Cen 1986  

NASA Technical Reports Server (NTRS)

The discovery of broad emission features between 3.2 and 3.6 microns were reported in the spectrum of Nova Cen 1986 (V842 Cen) some 300 days following outburst and remaining prominent for several months. The general characteristics of these features are similar to those attributed to polycyclic hydrocarbon (PAH) molecules in other dusty sources, although the relative strengths are different, and these observations provide the first clear evidence for molecular constituents other than graphite particles in the ejecta of novae.

Hyland, A. R. Harry; Mcgregor, P. J.

1989-01-01

212

Enhanced dissipation of PAHs from soil using mycorrhizal ryegrass and PAH-degrading bacteria.  

PubMed

The major aim of this experiment was to test the effects of a multi-component bioremediation system consisting of ryegrass (Lolium multiflorum), polycyclic aromatic hydrocarbons (PAHs)-degrading bacteria (Acinetobacter sp.), and arbuscular mycorrhizal fungi (Glomus mosseae) for cleaning up PAHs contaminated soil. Higher dissipation rates were observed in combination treatments: i.e., bacteria+ryegrass (BR), mycorrhizae+ryegrass (MR), and bacteria+mycorrhizae+ryegrass (BMR); than bacteria (B) and ryegrass (R) alone. The growth of ryegrass significantly (p<0.05) increased soil peroxidase activities, leading to enhanced dissipation of phenanthrene (PHE) and pyrene (PYR) from soil. Interactions between ryegrass with the two microbes further enhanced the dissipation of PHE and PYR. Mycorrhizal ryegrass (MR) significantly enhanced the dissipation of PYR from soil, PYR accumulation by ryegrass roots and soil peroxidase activities under lower PHE and PYR levels (0 and 50+50 mg kg(-1)). The present results highlighted the contribution of mycorrhiza and PAH-degrading bacteria in phytoremediation of PAH contaminated soil, however more detailed studies are needed. PMID:21176862

Yu, X Z; Wu, S C; Wu, F Y; Wong, M H

2011-02-28

213

PHOTOINDUCED TOXICITY OF PAHS AND ALKYLATED PAHS TO A MARINE INFAUNAL AMPHIPOD (RHEPOXYNIUS ABRONIUS)  

EPA Science Inventory

The marine infaunal amphipod Rhepoxynius abronius was exposed in standard 10-day toxicity tests to sediments contaminated with parent or alkylated PAHs. After exposures, mortalities (LC50 values) and the ability to rebury in control sediment (EC50 values) were determined. Survivo...

214

Improved GC\\/MS methods for measuring hourly PAH and nitro-PAH concentrations in urban particulate matter  

Microsoft Academic Search

This study presents two methods for the quantification of nitro-substituted and parent polycyclic aromatic hydrocarbons (NPAH and PAH, respectively), respectively, utilizing large volume injection gas chromatography\\/mass spectrometry (GC\\/MS). Both methods (PAH and NPAH, respectively) employed a programmed temperature vaporization injector (PTV) in solvent vent mode, optimized using standard solutions. For the PAH method, the precision of the PTV was comparable

Bernard S. Crimmins; Joel E. Baker

2006-01-01

215

Global time trends in PAH emissions from motor vehicles  

NASA Astrophysics Data System (ADS)

Emission from motor vehicles is the most important source of polycyclic aromatic hydrocarbons (PAHs) in urban areas. Emission factors of individual PAHs for motor vehicles reported in the literature varied 4 to 5 orders of magnitude, leading to high uncertainty in emission inventory. In this study, key factors affecting emission factors of PAHs (EF PAH) for motor vehicles were evaluated quantitatively based on thousands of EF PAH measured in 16 countries for over 50 years. The result was used to develop a global emission inventory of PAHs from motor vehicles. It was found that country and vehicle model year are the most important factors affecting EF PAH, which can be quantified using a monovariate regression model with per capita gross domestic production (purchasing power parity) as a sole independent variable. On average, 29% of variation in log-transformed EF PAH could be explained by the model, which was equivalent to 90% reduction in overall uncertainty on arithmetic scale. The model was used to predict EF PAH and subsequently PAH emissions from motor vehicles for various countries in the world during a period from 1971 to 2030. It was estimated that the global emission reached its peak value of approximate 101 Gg in 1978 and decreased afterwards due to emission control in developed countries. The annual emission picked up again since 1990 owing to accelerated energy consumption in China and other developing countries. With more and more rigid control measures taken in the developing world, global emission of PAHs is currently passing its second peak. It was predicted that the emission would decrease from 77 Gg in 2010 to 42 Gg in 2030.

Shen, Huizhong; Tao, Shu; Wang, Rong; Wang, Bin; Shen, Guofeng; Li, Wei; Su, Shenshen; Huang, Ye; Wang, Xilong; Liu, Wenxin; Li, Bengang; Sun, Kang

2011-04-01

216

PAH biomarkers in common eelpout (Zoarces viviparus) from Danish waters.  

PubMed

Eelpouts (Zoarces viviparus) sampled at surveillance stations during the fall of 2007 and spring 2008 in different Danish coastal areas, were studied for biomarkers of polycyclic aromatic hydrocarbons (PAHs) exposure and effects. Two analytical techniques, synchronous fluorescence spectrometry (SFS) and high-performance liquid chromatography with fluorescence detection (HPLC/F), were applied for detecting PAH metabolites in bile and urine. CYP1A activity, in this study regarded as potential biomarker of effect, was measured as 7-ethoxyresorufin-O-deethylase (EROD) activity in liver of eelpouts from different stations. Biliary PAH metabolite measurements were used for monitoring the environmental PAH load at the surveillance stations. There was found significant difference in biliary PAH metabolite content between sexes with male fish containing higher concentrations of PAH metabolites than females. The urinary PAH metabolite content did not show the same spatial trends as biliary PAH metabolites. However, fish from Aarhus Bight and Vejle Fjord had significantly higher levels of PAH metabolites in both urine and bile compared to the reference station Agersø. Normalisation methods applied for bile and urine matrices did not have any effect or only slightly reduced the coefficients of variation in data sets. The CYP1A activity in eelpout liver did not show the same spatial distribution trends between sampling sites as did biliary or urinary PAH metabolite contents. Male eelpouts showed significantly higher CYP1A activity than females in fall sampling period but there were no differences found in the spring period. General comparison between both seasons showed that eelpouts sampled in the fall had significantly higher CYP1A activity than fish sampled during spring season. Overall, the results of this study describe selected biomarker responses in eelpouts to environmental PAH load at the different areas along Danish coasts. PMID:21982560

Tairova, Zhanna M; Strand, Jakob; Chevalier, Julie; Andersen, Ole

2012-04-01

217

Interstellar PAH Analogs in the Laboratory: Comparison with Astronomical Data  

NASA Technical Reports Server (NTRS)

Polycyclic Aromatic Hydrocarbons (PAHs) are an important and ubiquitous component of carbon-bearing materials in space. PAHs are the best-known candidates to account for the IR emission bands (UIR bands) and PAH spectral features are now being used as new probes of the ISM. PAHs are also thought to be among the carriers of the diffuse interstellar absorption bands (DIBs). In the model dealing with the interstellar spectral features, PAHs are present as a mixture of radicals, ions and neutral species. PAH ionization states reflect the ionization balance of the medium while PAH size, composition, and structure reflect the energetic and chemical history of the medium. A major challenge for laboratory astrophysics is to reproduce (in a realistic way) the physical conditions that exist in the emission and/or absorption interstellar zones. An extensive laboratory program has been developed at NASA Ames to assess the physical and chemical properties of PAHs in such environments and to describe how they influence the radiation and energy balance in space and the interstellar chemistry. In particular, laboratory experiments provide measurements of the spectral characteristics of interstellar PAH analogs from the ultraviolet and visible range to the infrared range for comparison with astronomical data. This paper will focus on the recent progress made in the laboratory to measure the direct absorption spectra of neutral and ionized PAHs in the near-UV and visible range. Intrinsic band profiles and band positions of cold gas-phase PAHs can now be measured with high-sensitivity spectroscopy and directly compared to the astronomical data. Preliminary conclusions from the comparison of the laboratory data with astronomical observations will also be presented.

Salama, Farid

2005-01-01

218

[Concentrations and distribution characteristic of PAHs, PCBs and OCPs in the surface sediments of Qingtao coastal area].  

PubMed

PAHs were measured by gas chromatography-mass spectrometry (GC-MS) in the surface sediments collected from the southern Shandong Peninsula coastal area. Contents and distribution characterizations of PAHs, PCBs and OCPs in the area were discussed. The concentration of PAHs in the surface sediments decreased gradually from the inshore area to the offshore area. According to the ratio of P/A and Fl/Py, the release from combustion of fuel was one of the most major sources of PAHs in this area. The level of PCBs in the surface sediments was higher in the Jiaozhou Bay and southwest coast of Qingtao, and lower in the other area. The distribution of PCBs decreased gradually from the inshore to the offshore area. OCPs in surface sediments also decreased from the inshore to the offshore area. The HCHs data showed the area was polluted by agriculture and industry at the same time. There were only a few DDTs imported into the area in the recent years, and DDTs were decomposed by aerobic microbial degradation in surface sediment. The concentration of PAHs, PCBs and OCPs suggested that the potential risk of environmental pollution was low in the area. PMID:21250456

Wang, Jiang-Tao; Tan, Li-Ju; Zhang, Wen-Hao; Lian, Zi-Ru

2010-11-01

219

BIOAVAILABILITY OF PAHS FROM PYROGENIC AND PETROGENIC SOURCES MEASURED USING GLASS FISH  

EPA Science Inventory

Geochemical evidence indicates PAHs associated with pyrogenic sources behave differently than PAHs from petrogenic sources. There is also some evidence and supposition that PAHs from pyrogenic and petrogenic sources demonstrate differing bioavailability. In this study, we evaluat...

220

PAH refractory index as a source discriminant of hydrocarbon input from crude oil and coal in Prince William Sound, Alaska  

USGS Publications Warehouse

Geochemical correlation and differentiation of hydrocarbons from crude oils and coals is difficult. The complex mixture of the hydrocarbon constituents and the dynamic nature of these constituents in the environment as they weather contribute to this difficulty A new parameter, the polycyclic aromatic hydrocarbon (PAH) refractory index, is defined here to help in this correlation. The PAH refractory index is a ratio of two of the most refractory constituents of most crude oils, namely triaromatic steranes and monomethylchrysenes. These are among the most persistent compounds in oil after deposition in the environment and thus retain reliably the signature of the original petroleum input. This index is utilized in Prince William Sound (PWS) to differentiate three different oils, as well as to provide evidence that coal, not oil, is the dominant source of the PAHs which are prominent constituents of marine sediments from PWS and the Gulf of Alaska.Geochemical correlation and differentiation of hydrocarbons from crude oils and coals is difficult. The complex mixture of the hydrocarbon constituents and the dynamic nature of these constituents in the environment as they weather contribute to this difficulty. A new parameter, the polycyclic aromatic hydrocarbon (PAH) refractory index, is defined here to help in this correlation. The PAH refractory index is a ratio of two of the most refractory constituents of most crude oils, namely triaromatic steranes and monomethylchrysenes. These are among the most persistent compounds in oil after deposition in the environment and thus retain reliably the signature of the original petroleum input. This index is utilized in Prince William Sound (PWS) to differentiate three different oils, as well as to provide evidence that coal, not oil, is the dominant source of the PAHs which are prominent constituents of marine sediments from PWS and the Gulf of Alaska.

Hostettler, F. D.; Rosenbauer, R. J.; Kvenvolden, K. A.

1999-01-01

221

Determination of PAHs in particulate air by micellar liquid chromatography  

SciTech Connect

An acetonitrile/0.20M SDS mobile phase was used to determine PAHs by HPLC with fluorimetric detection. Because the peak area is greater the method is more sensitive than using an acetonitrile/water mobile phase. The method was applied to determine PAHs in particulate air samples and the results are in good agreement with those found by GC.

Kayali, M.N.; Rubio-Barroso, S.; Polo-Diez, L.M. (Complutense Univ. of Madrid (Spain). Dept. of Analytical Chemistry)

1994-01-01

222

ARIZONA BORDER STUDY--PAH IN REPLICATES ANALYTICAL RESULTS  

EPA Science Inventory

The Replicates/PAH database contains the analytical results of PAH concentrations in replicate samples. The samples were analyzed as part of the QA/QC protocols of the NHEXAS project. The class of analytes consist of 24 seperate compounds including the BAP series. The NHEXAS p...

223

Hydrogen Coverage of Interstellar PAHs (Polycyclic Aromatic Hydrocarbons).  

National Technical Information Service (NTIS)

The rate at which the CH bond in interstellar Polycyclic Aromatic Hydrocarbons (PAHs) rupture due to the absorption of a uv photon has been calculated. The results show that small PAHs (less than or equal to 25 carbon atoms) are expected to be partially d...

A. G. G. M. Tielens L. J. Allamandola J. R. Barker M. Cohen

1986-01-01

224

Generation of polycyclic aromatic hydrocarbons (PAHs) during woodworking operations.  

PubMed

Occupational exposures to wood dust have been associated with an elevated risk of sinonasal cancer (SNC). Wood dust is recognized as a human carcinogen but the specific cancer causative agent remains unknown. One possible explanation is a co-exposure to; wood dust and polycyclic aromatic hydrocarbons (PAHs). PAHs could be generated during incomplete combustion of wood due to heat created by use of power tools. To determine if PAHs are generated from wood during common wood working operations, PAH concentrations in wood dust samples collected in an experimental chamber operated under controlled conditions were analyzed. In addition, personal air samples from workers exposed to wood dust (n = 30) were collected. Wood dust was generated using three different power tools: vibrating sander, belt sander, and saw; and six wood materials: fir, Medium Density Fiberboard (MDF), beech, mahogany, oak and wood melamine. Monitoring of wood workers was carried out by means of personal sampler device during wood working operations. We measured 21 PAH concentrations in wood dust samples by capillary gas chromatography-ion trap mass spectrometry (GC-MS). Total PAH concentrations in wood dust varied greatly (0.24-7.95 ppm) with the lowest being in MDF dust and the highest in wood melamine dust. Personal PAH exposures were between 37.5-119.8 ng m(-3) during wood working operations. Our results suggest that PAH exposures are present during woodworking operations and hence could play a role in the mechanism of cancer induction related to wood dust exposure. PMID:23087908

Bruschweiler, Evin D; Danuser, Brigitta; Huynh, Cong Khanh; Wild, Pascal; Schupfer, Patrick; Vernez, David; Boiteux, Philippe; Hopf, Nancy B

2012-01-01

225

PAH bombardment by energetic particles: models and astrophysical implications  

NASA Astrophysics Data System (ADS)

Polycyclic Aromatic Hydrocarbons (PAHs) are an important and ubiquitous component of the Interstellar Medium (ISM) of galaxies. Interstellar PAHs are apparently able to withstand the rigors of the harsh environment of the ISM for some some 100 million years and thus are resilient against processing by UV and X-ray photons and supernova shock waves. PAHs in space are mainly studied through their characteristic emission bands, due to infrared fluorescence following the absorption of UV photons. This is the reason why the photophysics of PAHs in space has been extensively investigated. On the other hand, PAHs are also strongly affected by collisional processes, i.e. bombardment by high-velocity ions and electrons, arising from interstellar shocks, hot gas and cosmic rays. However, very little was known about the physics of the interaction between PAHs and high energy particles, especially in terms of PAH damage and destruction. This lack of information had made the interpretation of PAH observations difficult in regions subjected to such processes. Our research aims to fill this key gap in our understanding of the physics behind collisional processing of PAHs and to clarify how this affects the PAH evolution in the astrophysical context. We first describe the models we have developed, that take into account the molecular nature of the target PAH and allow for the first time a quantitative description of the collisional processing of PAH molecules by ions and electrons with energies between 10 eV and 10 keV (in shocks and hot gas) and between 5 MeV and 10 GeV (in cosmic rays). Specific models were needed because PAHs are molecules and not small solid fragments, thus the classical approach from solid state physics cannot be applied. We then show the applications of our models to observations, estimating the lifetime of PAHs against collisional processing in specific objects. We discuss the astrophysical implications of our findings on the considered sample, which includes very different objects such as supernova remnants, normal/starburst galaxies and galaxy clusters.

Micelotta, E.; Jones, A.; Tielens, A.

2011-05-01

226

3.3 ?m PAH observations of the central kiloparsecs of Centaurus A  

NASA Astrophysics Data System (ADS)

Aims: The aim of this work is to further investigate the nature of polycyclic aromatic hydrocarbon (PAH) excitation and emission especially in the context of tracing star formation in a variety of extragalactic environments. Here we turn our attention to the energetic environment of the closest active galactic nucleus (AGN) in our sample, Centaurus A. Methods: Using ISAAC on the ESO VLT UT1 (Antu) we have made high spatial resolution 3.3 ?m imaging observations of the central kiloparsec of CenA. These observations have been compared with star formation tracers in the near- and mid-infrared, as well as with mid-infrared tracers of nuclear activity. Results: The nucleus is not devoid of PAH emission, implying that the PAH particles are not destroyed in the nucleus as might be expected for such a harsh environment. However, we see the feature to continuum ratio decrease towards the AGN. As well, the 3.3 ?m PAH feature emission generally traces the sites of star formation in Cen A, but in detail there are spatial offsets, consistent with an earlier study of the starburst galaxies NGC 253 and NGC 1808. However, the feature-to-continuum ratio does not drop at the positions of star formation as was previously seen in that earlier study. The cause for this difference remains uncertain. Finally, our data reveal possible evidence for a nearly face-on, circular or spiral, dust structure surrounding the nucleus. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (Program 075.B-0618, PI: Tacconi-Garman).

Tacconi-Garman, L. E.; Sturm, E.

2013-03-01

227

Comparative Developmental Toxicity of Environmentally Relevant Oxygenated PAHs  

SciTech Connect

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in urban air, dust and in the soil of most industrial coal gassification, coal burning, coke production and wood preservation sites (Howsam and Jones 1998). It is widely recognized that PAHs pose risks to human health,having been associated with increased risks of systemic inflammation (Delfino et al. 2010), cardiopulmonary mortality (Lee et al. 2011; Lewtas 2007) and lung cancer mortality (Grant 2009; Hoshuyama et al. 2006). The potential risks may be especially acute for the developing fetus and infant where PAH exposures have been linked to low birth weight, intrauterine growth retardation, in-utero mortality and lower intelligence (Dejmek et al. 1999; Dejmek et al. 2000; Perera et al. 1999; Perera et al. 2009; Perera et al. 2006; Perera et al. 1998; Wu et al. 2010). Despite the more than two decades of intensive study devoted to parent PAHs, they are only part of the hazard spectrum from PAH contamination.

Knecht, Andrea; Goodale, Britton; Truong, Lisa; Simonich, Michael; Swanson, Annika; Matzke, Melissa M.; Anderson, Kim A.; Waters, Katrina M.; Tanguay, Robert

2013-09-01

228

Size distribution and dry deposition of road dust PAHs  

SciTech Connect

The size distribution of polycyclic aromatic hydrocarbons (PAHs) for road dust and for the engine exhaust of both gasoline-powered cars and motorcycles was investigated. In addition, by using the measured size distribution data, monitoring and modeling the PAH dry deposition, the contribution fraction of road dust on the dry deposition materials was also studied. Twenty-one PAHs were analyzed primarily by using a gas chromatograph/mass spectrometer (GC/MS). The mass median diameters (MMDs) of 21 individual PAHs for resuspendable road dust (cut size < 100 {micro}m) ranged between 63.4 {micro}m and 65.5 {micro}m. However, the MMDs of total-PAH size distributions for the engine exhaust of both gasoline-powered cars and four-stroke motorcycles averaged 0.45 {micro}m and 0.35 {micro}m, respectively, which were near the MMDs of PAHs (average 0.50 {micro}m) in the ambient air of traffic intersections. Suspended particle-phase total PAHs in the ambient air of traffic intersections were found to be more than 90% of the result of the automobile exhaust; that is, less than 10% of the amount was contributed by the road dust. However, the modeled MMDs of 21 individual PAHs on the dry deposition material were between 22.1 {micro}m and 44.6 {micro}m, and the contribution fraction of road dust on the PAH dry deposition was found to be more than 95%, even though the suspendable ambient-air PAHs were mainly from the mobile exhaust.

Yang, H.H.; Chiang, C.F. [Chaoyang Univ. of Technology, Taichung (Taiwan, Province of China). Dept. of Environmental Management] [Chaoyang Univ. of Technology, Taichung (Taiwan, Province of China). Dept. of Environmental Management; Lee, W.J. [National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Environmental Engineering] [National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Environmental Engineering; Hwang, K.P. [National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Transportation and Communication Management] [National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Transportation and Communication Management; Wu, E.M.Y. [Kaohsiung Municipal Government (Taiwan, Province of China). Dept. of Environmental Protection] [Kaohsiung Municipal Government (Taiwan, Province of China). Dept. of Environmental Protection

1999-07-01

229

Ozone oxidation of surface-adsorbed polycyclic aromatic hydrocarbons (PAHs): Role of PAH-surface interaction  

NASA Astrophysics Data System (ADS)

We examine the effects of substrate on the oxidation of surface-bound anthracene and pyrene by gas-phase O3 using density functional theory (B3LYP/6-31g**). We find that the PAH-substrate interaction may result in the inhibition of some oxidation pathways involving nonplanar intermediates. The energy penalty for partial detachment from the surface is estimated and accounted for in the thermodynamic analysis of the reaction pathways. For anthracene, at least one oxidation pathway may be inhibited by strong interaction with the surface, thus impacting the rate of anthraquinone formation and possibly the observed rate of anthracene loss due to oxidation. Furthermore, the formation of other nonplanar products which have been proposed previously may be inhibited. When larger PAHs such as pyrene are surface-adsorbed, ring-opening reactions that proceed via the Criegee mechanism may be inhibited.

McNeill, V. Faye; Chu, Sophie; Sands, Sophia; Tomasik, Michelle

2010-05-01

230

Modelling the physical and chemical evolution of PAHs and PAH-related species in astrophysical environments  

NASA Astrophysics Data System (ADS)

An active carbon chemistry is observed at the border of photo-dissociation regions (PDRs), involving small hydrocarbons, polycyclic aromatic hydrocarbon (PAH) macromolecules and evaporating very small grains (VSGs). In this context, we aim at quantifying the physical and chemical evolution of PAHs (hydrogenation and charge states, aggregation, and complexation with heavy atoms) as a function of the local physical conditions (radiation field, temperature, density, abundances of atomic and molecular hydrogen, electrons and heavy atoms). We have developed a numerical model that follows the time dependency of the abundance and internal energy of each species. In this paper, we use this model to calculate the hydrogenation and charge states of coronene C24H12 as an interstellar PAH prototype. We take advantage of recent results on photodissociation and reaction rates and provide guidelines for future laboratory studies. Reaction rates of coronene-derived radical cations with H and H2 are found to be sufficiently constrained by experiments, whereas the absence of experimental data for neutral species is critical.

Montillaud, J.; Joblin, C.; Toublanc, D.

2011-03-01

231

Biodegradation aspects of polycyclic aromatic hydrocarbons (PAHs): a review.  

PubMed

PAHs are aromatic hydrocarbons with two or more fused benzene rings with natural as well as anthropogenic sources. They are widely distributed environmental contaminants that have detrimental biological effects, toxicity, mutagenecity and carcinogenicity. Due to their ubiquitous occurrence, recalcitrance, bioaccumulation potential and carcinogenic activity, the PAHs have gathered significant environmental concern. Although PAH may undergo adsorption, volatilization, photolysis, and chemical degradation, microbial degradation is the major degradation process. PAH degradation depends on the environmental conditions, number and type of the microorganisms, nature and chemical structure of the chemical compound being degraded. They are biodegraded/biotransformed into less complex metabolites, and through mineralization into inorganic minerals, H(2)O, CO(2) (aerobic) or CH(4) (anaerobic) and rate of biodegradation depends on pH, temperature, oxygen, microbial population, degree of acclimation, accessibility of nutrients, chemical structure of the compound, cellular transport properties, and chemical partitioning in growth medium. A number of bacterial species are known to degrade PAHs and most of them are isolated from contaminated soil or sediments. Pseudomonas aeruginosa, Pseudomons fluoresens, Mycobacterium spp., Haemophilus spp., Rhodococcus spp., Paenibacillus spp. are some of the commonly studied PAH-degrading bacteria. Lignolytic fungi too have the property of PAH degradation. Phanerochaete chrysosporium, Bjerkandera adusta, and Pleurotus ostreatus are the common PAH-degrading fungi. Enzymes involved in the degradation of PAHs are oxygenase, dehydrogenase and lignolytic enzymes. Fungal lignolytic enzymes are lignin peroxidase, laccase, and manganese peroxidase. They are extracellular and catalyze radical formation by oxidation to destabilize bonds in a molecule. The biodegradation of PAHs has been observed under both aerobic and anaerobic conditions and the rate can be enhanced by physical/chemical pretreatment of contaminated soil. Addition of biosurfactant-producing bacteria and light oils can increase the bioavailability of PAHs and metabolic potential of the bacterial community. The supplementation of contaminated soils with compost materials can also enhance biodegradation without long-term accumulation of extractable polar and more available intermediates. Wetlands, too, have found an application in PAH removal from wastewater. The intensive biological activities in such an ecosystem lead to a high rate of autotrophic and heterotrophic processes. Aquatic weeds Typha spp. and Scirpus lacustris have been used in horizontal-vertical macrophyte based wetlands to treat PAHs. An integrated approach of physical, chemical, and biological degradation may be adopted to get synergistically enhanced removal rates and to treat/remediate the contaminated sites in an ecologically favorable process. PMID:19442441

Haritash, A K; Kaushik, C P

2009-09-30

232

PAH concentrations simulated with the AURAMS-PAH chemical transport model over Canada and the USA  

NASA Astrophysics Data System (ADS)

The offline Eulerian AURAMS (A Unified Regional Air quality Modelling System) chemical transport model was adapted to simulate airborne concentrations of seven PAHs (polycyclic aromatic hydrocarbons): phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene + triphenylene, and benzo[a]pyrene. The model was then run for the year 2002 with hourly output on a grid covering southern Canada and the continental USA with 42 km horizontal grid spacing. Model predictions were compared to ~5000 24 h-average PAH measurements from 45 sites, most of which were located in urban or industrial areas. Eight of the measurement sites also provided data on particle/gas partitioning which had been modelled using two alternative schemes. This is the first known regional modelling study for PAHs over a North American domain and the first modelling study at any scale to compare alternative particle/gas partitioning schemes against paired field measurements. The goal of the study was to provide output concentration maps of use to assessing human inhalation exposure to PAHs in ambient air. Annual average modelled total (gas + particle) concentrations were statistically indistinguishable from measured values for fluoranthene, pyrene and benz[a]anthracene whereas the model underestimated concentrations of phenanthrene, anthracene and chrysene + triphenylene. Significance for benzo[a]pyrene performance was close to the statistical threshold and depended on the particle/gas partitioning scheme employed. On a day-to-day basis, the model simulated total PAH concentrations to the correct order of magnitude the majority of the time. The model showed seasonal differences in prediction quality for volatile species which suggests that a missing emission source such as air-surface exchange should be included in future versions. Model performance differed substantially between measurement locations and the limited available evidence suggests that the model's spatial resolution was too coarse to capture the distribution of concentrations in densely populated areas. A more detailed analysis of the factors influencing modelled particle/gas partitioning is warranted based on the findings in this study.

Galarneau, E.; Makar, P. A.; Zheng, Q.; Narayan, J.; Zhang, J.; Moran, M. D.; Bari, M. A.; Pathela, S.; Chen, A.; Chlumsky, R.

2014-04-01

233

Laboratory Investigations of the Formation of Superhydrogenated PAHs  

NASA Astrophysics Data System (ADS)

We present experimental investigations of the formation of superhydrogenated polycyclic aromatic hydrocarbons (PAHs) through exposure of neutral PAHs to atomic hydrogen. Post irradiation thermal desorption measurements demonstrate that it is possible to form superhydrogenated coronene molecules with surprisingly high numbers of additional H atoms. We observe species with in excess of 20 additional H atoms, approaching the fully hydrogenated limit, perhydrocoronene. Scanning tunneling microscopy (STM) measurements provide insight into the changes to the electronic structure of the coronene species as a result of the hydrogenation process. Submolecular structure observed in the STM images indicates that a range of different sites on the coronene molecule are hydrogenated. The formation of PAHs with such high degrees of superhydrogenation may have important implications for molecular hydrogen formation in the ISM. Recent density functional theory calculations1 have indicated the efficient formation of H2 through a combination of hydrogenation and abstraction reactions involving neutral PAHs and their superhydrogenated forms. Although previous measurements by Menella2 have demonstrated the efficiency of both H addition and subsequent abstraction reactions involving a complex aromatic carbon grain mimic, the measurements reported here provide the first direct observation of neutral PAH superhydrogenation by H atom addition. The role played by PAHs in H2 formation is suggested by observations of a correlation between H2 and PAHs abundances in photodissociation regions3. Routes to H2 involving PAH cations have been investigated by several groups4-6 and the role played by anions has also been considered7. The present work demonstrates that neutral PAHs may also provide a formation route for this most important of interstellar molecules.

Thrower, J.; Friis, E.; Jorgensen, B.; Nilsson, L.; Baouche, S.; Balog, R.; Cassidy, A.; Hornekae, L.

2011-05-01

234

The Computed Infrared Spectra of a Variety of [FePAH]+ Complexes: Mid- and Far-Infrared Features  

NASA Astrophysics Data System (ADS)

The effects of the ?-coordination of an Fe atom on the mid- and far-infrared spectra of a mixture of cationic polycyclic aromatic hydrocarbons (PAHs), e.g., pyrene (C16H10), anthanthrene (C22H12), coronene (C24H12), ovalene (C32H14), circumpyrene (C42H16), and circumcoronene (C54H18), are studied by Density Functional Theory based calculations. In the mid-infrared range (3-20 ?m), by comparison with the bare PAH+ spectrum, we found (1) an increase of the intensity ratio of the C-H stretching and C-H out-of-plane bending bands with respect to the intense CC stretching band and (2) a shift of the band positions and a characteristic profile with a steep blue rise and an extended red tail for the CC stretching and CH out-of-plane bending bands. None of these features appears inconsistent with the observed aromatic infrared band spectrum. In the far-infrared range (? > 20 ?m), the presence of a ?-coordinated Fe atom induces many new bands as (1) some vibrational modes of the PAH are activated due to symmetry reduction and (2) new modes involving the motion of the Fe atom occur. In particular, an accumulation point due to the activation of the Fe-PAH stretching mode is observed at around 40 ?m. This range is suggested to contain the spectral fingerprint for the presence of [M-PAH]+ (M=Fe, Si, Mg) complexes in the interstellar medium. Additional features in the [60-300] ?m range are found for complexes with large PAHs. The obtained results are discussed in the light of past, present, and future astronomical missions, among which are the Herschel Space Observatory and the SPICA telescope for the far-infrared domain.

Simon, A.; Joblin, C.

2010-03-01

235

Strong Impact on the Polycyclic Aromatic Hydrocarbon (PAH)-Degrading Community of a PAH-Polluted Soil but Marginal Effect on PAH Degradation when Priming with Bioremediated Soil Dominated by Mycobacteria?  

PubMed Central

Bioaugmentation of soil polluted with polycyclic aromatic hydrocarbons (PAHs) is often disappointing because of the low survival rate and low activity of the introduced degrader bacteria. We therefore investigated the possibility of priming PAH degradation in soil by adding 2% of bioremediated soil with a high capacity for PAH degradation. The culturable PAH-degrading community of the bioremediated primer soil was dominated by Mycobacterium spp. A microcosm containing pristine soil artificially polluted with PAHs and primed with bioremediated soil showed a fast, 100- to 1,000-fold increase in numbers of culturable phenanthrene-, pyrene-, and fluoranthene degraders and a 160-fold increase in copy numbers of the mycobacterial PAH dioxygenase gene pdo1. A nonpolluted microcosm primed with bioremediated soil showed a high rate of survival of the introduced degrader community during the 112 days of incubation. A nonprimed control microcosm containing pristine soil artificially polluted with PAHs showed only small increases in the numbers of culturable PAH degraders and no pdo1 genes. Initial PAH degradation rates were highest in the primed microcosm, but later, the degradation rates were comparable in primed and nonprimed soil. Thus, the proliferation and persistence of the introduced, soil-adapted degraders had only a marginal effect on PAH degradation. Given the small effect of priming with bioremediated soil and the likely presence of PAH degraders in almost all PAH-contaminated soils, it seems questionable to prime PAH-contaminated soil with bioremediated soil as a means of large-scale soil bioremediation.

Johnsen, Anders R.; Schmidt, Stine; Hybholt, Trine K.; Henriksen, Sidsel; Jacobsen, Carsten S.; Andersen, Ole

2007-01-01

236

Modeling the PAH Emission Spectra of Protoplanetary and Debris Disks  

NASA Astrophysics Data System (ADS)

The 3.3, 6.2, 7.7, 8.6 and 11.3 micron emission features of polycyclic aromatic hydrocarbon (PAH) molecules have been detected in protoplanetary disks around Herbig Ae/Be stars and T Tauri stars and in debris disks around main-sequence stars. PAHs play an important role in the thermal budget and chemistry of the gas in the disk, by providing photoelectrons for heating the gas and large surface areas for chemical reactions. Stochastically heated by a single UV/visible photon, the PAH emission is spatially more extended than large grains and therefore, the disks can be more easily resolved at the PAH emission bands. We propose to model the PAH emission spectra of protoplanetary and debris disks obtained by Spitzer and ISO. We will first calculate the temperature probability distribution functions dP/dT for both neutral and ionized PAHs of a wide range of sizes, at a wide range of radial distances (from the central star) in disks illuminated by stars of a wide range of spectral types. By modeling the PAH emission of dust disks, we will be able (1) to derive the abundance, size and spatial distributions of PAHs; (2) to derive the PAH photoelectric heating rates which dominate the gas heating in the disk surface layers; and (3) to see how the abundance and properties of the PAHs vary among disks at different evolutionary stages and illuminated by stars of different parameters (e.g. luminosity, spectral type). This program will create a web-based ``library'' of the temperature distribution functions dP/dT of PAHs (and their emission spectra and photoelectric heating rates) as a function of size, charge state, and radial distance in disks illuminated by stars of different spectral types. This library, a useful tool for interpreting the PAH emission features of dust disks obtained by Spitzer and for understanding the disk chemistry, will be made publicly available by April 2007 via the WWW at http://www.missouri.edu/~lia/.

Li, Aigen; Lunine, J. I.

2006-05-01

237

Maturation of Rb+ and PAH accumulation by rabbit anterior uvea and choroid plexus  

SciTech Connect

In vitro accumulation of radioactive para-aminohippuric acid (/sup 3/H-PAH) and rubidium (/sup 86/Rb+) by the anterior uvea, ciliary processes, and the choroid plexus was evaluated in tissues from newborn and various aged rabbits. Accumulation of PAH was present in the anterior uvea at 1 day of age (tissue to media ratio, T/M, of 2.1 +/- 0.2) and remained at this level for the first 14 days of life. Accumulation did not rise to adult levels until 21 days of age (T/M 5.5 +/- 0.6). Rubidium accumulation in the anterior uvea, a measure of Na+, K+-pump activity, was higher than adult values 6 hr after birth (T/M25.2 +/- 0.9). Activity remained elevated through day 28 and did not fall to adult levels until day 60 (T/M 13.4 +/- 0.6). Accumulation studies on isolated ciliary processes were similar to those obtained from anterior uveal tissue. Daily subcutaneous injections of penicillin (300,000 units/kg/day) for 1 week had no effect on anterior uvea PAH accumulation (penicillin T/M was 1.7 +/- 0.1 and saline control T/M was 2.0 +/- 0.2). Accumulation of either /sup 3/H-PAH or /sup 86/Rb+ by the choroid plexus was present 1 day after birth in amounts that were similar to adult values and did not change during the 90 days of testing.

Krupin, T.; Fritz, C.; Becker, B.

1985-02-01

238

Distribution, sources, and potential risk of polycyclic aromatic hydrocarbons (PAHs) in drinking water resources from Henan Province in middle of China.  

PubMed

Distribution and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in drinking water resources have been carried out for the first time in Henan Province, China. Water samples collected from four river systems and their tributaries, as well as groundwater resources, were analyzed according to EPA method 525.2. Total of 68 water samples were collected in 18 cities in Henan province in May, August and November, 2001. Concentrations of sum of 16 priority PAHs in water samples ranged from 15 to 844 ng/L with a mean value of 178 +/- 210 ng/L (n = 68). The spatial and temporal distribution of PAHs showed that the Huanghe and the Huaihe river systems had relatively higher concentrations of total PAHs. Higher concentrations of total PAHs were observed in August and November than in May, with respective mean values of 262, 232 and 33.6 ng/L. Ratios of Ant/(Ant + Phe) and Flur/(Flur + Pyr) were calculated to evaluate the possible sources of PAH contamination, which indicated that the coal combustion sources were the main contributors to PAHs in most drinking water resources. Some petrogenic (or pyrolytic) sources of PAHs were also found. The toxic equivalency factors (TEFs) were used to calculate benzo[a]pyrene equivalents (BaPE) for water samples. The average value of BaPE was 0.6 ng/L. The values in most stations were much lower than the guideline values in drinking water of Chinese Environmental Protection Agency (CEPA, 2.8 ng/L) and the US Environmental Protection Agency (US EPA, 200 ng/L). Overall, the drinking water resources in Henan province showed some carcinogenic potential. PMID:18074237

Ma, Ying-ge; Cheng, Jin-ping; Jiao, Fei; Duo, Ke-xin; Rong, Zheng; Li, Ming; Wang, Wen-hua

2008-11-01

239

Emissions of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs from heavy-duty diesel vehicles with DPF and SCR.  

PubMed

In total, 24 polycyclic aromatic hydrocarbons (PAHs) in both gas and particle phases and 35 nitro-PAHs in particle phase were analyzed in the exhaust from heavy-duty diesel vehicles equipped with after-treatment for particulate matter (PM) and NO(x) control. The test vehicles were carried out using a chassis dynamometer under highway cruise, transient Urban Dynamometer Driving Schedule (UDDS), and idle operation. The after-treatment efficiently abated more than 90% of the total PAHs. Indeed, the particle-bound PAHs were reduced by > 99%, and the gaseous PAHs were removed at various extents depending on the type of after-treatment and the test cycles. The PAHs in gas phase dominated the total PAH (gas + particle phases) emissions for all the test vehicles and for all cycles; that is, 99% of the two-ring and 98% of the three-ring and 97% of the four-ring and 95% of the carcinogenic PAHs were in the gas-phase after a diesel particle filter (DPF) and not bound to the very small amount of particulate matter left after a DPF. Consequently, an evaluation of the toxicity of DPF exhaust must include this volatile fraction and cannot be based on the particle fraction only. The selective catalytic reduction (SCR) did not appear to promote nitration of the PAHs in general, although there might be some selective nitration of phenanthrene. Importantly the after-treatment reduced the equivalent B[a]P (B[a]Peq) emissions by > 95%, suggesting a substantial health benefit. Implications: This study demonstrated that after-treatments, including diesel particulate filters (DPF), diesel oxidation catalysts (DOC), and selective catalytic reduction (SCR), significantly reduce the emissions of PAHs from heavy-duty diesel engines. The gas-phase PAHs dominate the total PAH (gas + particle phases) emissions from heavy-duty diesel vehicles retrofitted with various DPFs and not bound to the very small amount of particulate matter left after a DPF. Consequently, an evaluation of the toxicity of DPF exhaust must also include this volatile fraction and cannot be based on the particle fraction only. PMID:24010380

Hu, Shaohua; Herner, Jorn D; Robertson, William; Kobayashi, Reiko; Chang, M C Oliver; Huang, Shiou-Mei; Zielinska, Barbara; Kado, Norman; Collins, John F; Rieger, Paul; Huai, Tao; Ayala, Alberto

2013-08-01

240

Deuterium Enrichment of PAHs by VUV Irradiation of Interstellar Ices  

NASA Technical Reports Server (NTRS)

Laboratory results demonstrate that polycyclic aromatic hydrocarbons (PAHs) rapidly exchange their hydrogen atoms with those of nearby molecules when they are frozen into low-temperature ices and exposed to vacuum ultraviolet radiation. As a result, PAHs quickly become deuterium-enriched when VUV irradiated in D-containing ices. This mechanism has important consequences for several astrophysical issues owing to the ubiquitous nature of PAHs in the interstellar medium. For example, this process may explain the deuterium enrichments found in PAHs in meteorites and interplanetary dust particles. These results also provide general predictions about the molecular siting of the deuterium on aromatic materials in meteorites if this process produced a significant fraction of their D-enrichment.

Bernstein, Max P.; Sandford, Scott A.; Allamandola, Louis J.; Gillette, J. Seb; Zare, Richard N.; DeVincenzi, Donald (Technical Monitor)

1998-01-01

241

PAH formation in carbon-rich circumstellar envelopes  

NASA Technical Reports Server (NTRS)

While there is growing observational evidence that some fraction of interstellar carbon is in polycyclic aromatic hydrocarbons (PAH's), the mechanisms by which these molecules might be formed have not been extensively studied. A detailed investigation of PAH production in the outflowing molecular envelopes of carbon-rich red giant star is presented. The gasphase kinetics of a chemical reaction mechanism developed to study soot production in hydrocarbon flames is modified to apply in circumstellar environments. It was found that astrophysically significant quantities of PAH's can be formed in carbon star envelopes provided the gas is sufficiently dense and resides for a long time in the temperature range of 900 to 1100 k. The precise yield of PAH's is very sensitive to astronomical parameters of the envelope (e.g., mass loss rate, outflow velocity, and acetylene abundance) and certain poorly determined chemical reaction rates.

Feigelson, Eric D.; Frenklach, Michael

1989-01-01

242

Distribution of polycyclic aromatic hydrocarbons (PAHs) and sterols in termite nest, soil, and sediment from Great Kwa River, SE Nigeria.  

PubMed

Costal sediment samples from Great Kwa River as well as adjoining termite nest and soil samples were analyzed for quantitative determination of polycyclic aromatic hydrocarbons (PAHs) and sterols using gas chromatography-mass spectrometry (GC-MS) in order to access the possibility of transport of biologically produced PAHs/sterols from termite nest to the sediments. The total PAH concentrations (sum of parent and alkyl) for the sediments ranged between 131.96 and 139.35 ng/g dry weight (dw) while those for the nest and soil samples were in the range 9.51-9.71 and 71.85-77.26 ng/g dw, respectively. These levels of PAHs in sediments were relatively low compared to other urban/industrial Asian and American countries. No evidence of the usual biologically produced PAHs was found, thus reducing the likelihood of transport of these compounds from the nest to the sediments. The absence of parent and alkyl PAHs in central compartment of the nest may reflect the selective fern leaves feeding pattern of the dominant termite species prevalent in the vicinity of the study site. Utilization of six selected PAH ratios such as Fla/(Fla + Pyr) (0.4-0.5), Ant/(Ant + Phe) (0.25-0.90), BaA/(BaA + Chrys) (0.45-0.61), MP/P (0.05-6.81), 1,7/(1,7 + 2,6)-DMP (0.61-0.95), and LPAH/HPAH ( 2.80-3.80) allows discrimination of PAH sources for the samples to be made with a mixed source dominance observed. Examination of sterol distributions in the samples shows relatively high abundance of cholest-5-en-3?-ol in central compartment of the nest, considered here as a consequence of metabolic conversion of phyto-/fungi sterols in the tissues of the termite species. The relatively reduced levels of stanol compounds in central compartment of the nest may be associated with their utilization by the termites for growth and development. PMID:22544040

Oyo-Ita, Orok Esu; Oyo-Ita, Inyang Okon; Ugim, Samuel Ugim

2013-02-01

243

Integrated diagnostics  

NASA Technical Reports Server (NTRS)

Recently completed projects in which advanced diagnostic concepts were explored and/or demonstrated are summarized. The projects begin with the design of integrated diagnostics for the Army's new gas turbine engines, and advance to the application of integrated diagnostics to other aircraft subsystems. Finally, a recent project is discussed which ties together subsystem fault monitoring and diagnostics with a more complete picture of flight domain knowledge.

Hunthausen, Roger J.

1988-01-01

244

Investigating Electronic Properties of Ionized PAH Clusters  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbon (PAH) clusters have been proposed as candidates for evaporating very small grains that are revealed by their mid-IR emission at the surface of UV-irradiated clouds in interstellar space. This motivates studies on the photostability and spectroscopic signatures of such species to validate their presence in interstellar environments and constrain their survival therein. We have used the molecular beam chamber SAPHIRS and the photoelectron-photoion coincidence spectrometer DELICIOUS II at the SOLEIL synchrotron facility to characterize the electronic properties of cationic coronene (C24H12) clusters up to the pentamer. These experimental results are analysed in the light of electronic structure calculations. In particular a Density Functional Tight Binding + Configuration Interaction scheme is developed to describe charge delocalization in these large systems and calculate the ionization potential, vibrational spectra, and charge transfer excited states. For the coronene dimer cation, complementary measurements are performed with the PIRENEA set-up to quantify some of the electronic transitions, in particular their oscillator strengths that cannot be extracted from the photoelectron spectroscopy. Emphasis will be put on the evolution of the spectra with cluster size. M. Rapacioli, C. Joblin and P. Boissel Astron. & Astrophys. 429, 193-204 (2005) G. Garcia, H. Soldi-Lose and L. Nahon Rev. Sci. Instrum. 80, 023102 (2009) Joint ANR project GASPARIM, ANR-10-BLAN-501 M. Rapacioli, A. Simon, L. Dontot and F. Spiegelman Phys. Status Solidi B 249 (2) 245-258 (2012)

Joblin, C.; Kokkin, D.; Bonnamy, A.; Toublanc, D.; Rapacioli, M.; Simon, A.; Dontot, L.; Gamboa, A.; Spiegelman, F.; Parneix, P.; Pino, T.; Pirali, O.; Feraud, G.; Friha, H.; Falvo, C.; Brechignac, P.; Garcia, G.; Nahon, L.; Mulas, G.

2012-06-01

245

Plumbagin reverses proliferation and resistance to apoptosis in experimental PAH.  

PubMed

Like cancer, pulmonary arterial hypertension (PAH) is characterised by a pro-proliferative and anti-apoptotic phenotype. In PAH, pulmonary artery smooth muscle cell (PASMC) proliferation is enhanced and apoptosis suppressed. The sustainability of this phenotype requires the activation of pro-survival transcription factors, such as signal transducer and activator of transcription (STAT)3 and nuclear factor of activated T-cells (NFAT). There are no drugs currently available that are able to efficiently and safely inhibit this axis. We hypothesised that plumbagin (PLB), a natural organic compound known to block STAT3 in cancer cells, would reverse experimental pulmonary hypertension. Using human PAH-PASMC, we demonstrated in vitro that PLB inhibits the activation of the STAT3/NFAT axis, increasing the voltage-gated K(+) current bone morphogenetic protein receptor type II (BMPR2), and decreasing intracellular Ca(2+) concentration ([Ca(2+)](i)), rho-associated coiled-coil containing protein kinase (ROCK)1 and interleukin (IL)-6, contributing to the inhibition of PAH-PASMC proliferation and resistance to apoptosis (proliferating cell nuclear antigen (PCNA), TUNEL, Ki67 and anexine V). In vivo, PLB oral administration decreases distal pulmonary artery remodelling, mean pulmonary artery pressure and right ventricular hypertrophy without affecting systemic circulation in both monocrotaline- and suden/chronic hypoxia-induced PAH in rats. This study demonstrates that the STAT3/NFAT axis can be therapeutically targeted by PLB in human PAH-PASMC and experimental PAH rat models. Thus, PLB could be considered a specific and attractive future therapeutic strategy for PAH. PMID:22496325

Courboulin, Audrey; Barrier, Marjorie; Perreault, Tanya; Bonnet, Pierre; Tremblay, Veronique L; Paulin, Roxane; Tremblay, Eve; Lambert, Caroline; Jacob, Maria H; Bonnet, Sandra N; Provencher, Steeve; Bonnet, Sébastien

2012-09-01

246

Polycyclic Aromatic Hydrocarbons and Astrophysics: The State of the Pah Model and a Possible Tracer of Nitrogen in Carbon-Rich Dust  

NASA Technical Reports Server (NTRS)

Over the past fifteen years, thanks to significant, parallel advancements in observational, experimental, and theoretical techniques, tremendous strides have been made in our understanding of the role aromatic materials play in the interstellar medium (ISM). Twenty years ago, the possible existence of an abundant population of large, carbon-rich molecules in the ISM was unthinkable. Today, the unmistakable spectroscopic signatures of polycyclic aromatic hydrocarbon molecules (PAHs) - shockingly large molecules by the standards of traditional interstellar chemistry - are recognized throughout the Universe. In this paper, we will examine the current state of the interstellar PAH model and its utility as a diagnostic tool to derive insight into the nature of the interstellar PAH population. As an example of this application, we will examine the results of our recent spectroscopic studies of polycyclic aromatic nitrogen heterocycles (PANHs)-PAHs with an atom of nitrogen substituted into the aromatic skeleton-and discuss a possible tracer of such species amongst the interstellar PAH emission bands in the latest observational data.

Hudgins, Douglas M.; Allamandola, Louis J.

2003-01-01

247

Kinetics of biodegradation of binary and ternary mixtures of PAHs.  

PubMed

The kinetics of biodegradation of mixtures of polycyclic aromatic hydrocarbons (PAHs) by Sphingomonas paucimobilis strain EPA505 were investigated. The investigation focused on three- and four-ring PAHs, specifically 2-methylphenanthrene, fluoranthene, and pyrene. Uptake rates in aerobic batch suspended cultivations were measured for the individual PAHs and their binary and ternary mixtures. It was observed that kinetics were influenced by the mixture composition and the kinetic properties of the components. A material balance equation containing the Monod model was numerically fitted to uptake data to determine extant kinetic parameters for the individual PAHs. Similarly, equations containing kinetic interaction models derived from enzyme kinetics were fitted to the uptake data obtained from experiments with binary and ternary mixtures. The investigation considered the following interaction types: no-interaction (Monod), pure competitive interaction, noncompetitive or mixed-type interaction, uncompetitive inhibition, and nonspecific interaction based on pure competition (SKIP). Model fit was evaluated based on probabilistic and statistical criteria and inferences were reached about underlying interaction mechanisms based on model fit. Mixture kinetics were most adequately simulated by the pure competitive interaction model with mutual substrate exclusivity. This model is fully predictive, relying only on parameters determined in the sole-PAH experiments. It was shown that for low percent inhibition values and with limited data, pure competitive interaction kinetics may not be evident, resembling no-interaction kinetics. This study is a reasonable starting point for understanding and modeling biodegradation of complex PAH mixtures in engineered and natural systems. PMID:17115447

Dimitriou-Christidis, Petros; Autenrieth, Robin L

2007-07-01

248

Steps Toward Identifying PAHs: A Child's Garden of Recent Results  

NASA Technical Reports Server (NTRS)

Based on over two decades of experimental, observational and theoretical studies by scientists around the world. It is now widely accepted that the composite emission of mixtures of vibrationally-excited PAHs and PAH ions can accommodate the general pattern of band positions, intensities, and profiles observed in the discreet IR emission features of carbon-rich interstellar dust, as well as the variations in those characteristics. These variations provide insight into the detailed nature of the emitting PAH population and reflect conditions within the emitting regions giving the population enormous potential as probes of astrophysical environments. Moreover, the ubiquity and abundance of this material has impacts that extend well beyond the IR. In this presentation we will examine recent, combined experimental, theoretical, and observational studies that indicate that nitrogen-substituted PAHs represent an important component of the interstellar dust population, and we will go on to explore some of the ramifications of this result. We will also explore the results of recent experimental studies of the strong, low-lying electronic transitions of ionized PAH ions in the Near-IR (0.7 - 2.5 microns) and explore the role that these transitions might play in pumping the PAH IR emission in regions of low-excitation.

Hudgins, Douglas M.

2005-01-01

249

Lightning Ratios  

NSDL National Science Digital Library

Using satellites and ground-based detection instruments, researchers have now mapped out lightning ratios for the continental United States. The Lightning Ratios site, from Space Science News (NASA), provides recent data in the form of a vibrant color map (.pdf or .jpg) of cloud-to-cloud lightning to cloud-to-ground lightning over the continental United States.

250

Isolation of polycyclic aromatic hydrocarbons (PAHs)-degrading Mycobacterium spp. and the degradation in soil  

Microsoft Academic Search

The goal of this study was to isolate PAHs degraders that can utilize PAHs associated with soil particulates and investigate the biodegradation of PAHs on agar plate, in liquid culture and soil. Two Mycobacterium strains (NJS-1 and NJS-P) were isolated from PAHs-contaminated farmland soil using enrichment based on soil slurry. The isolates could degrade five test PAHs including pyrene, phenanthrene,

Jun Zeng; Xiangui Lin; Jing Zhang; Xuanzhen Li

2010-01-01

251

SPITZER SPECTROSCOPY OF INFRARED-LUMINOUS GALAXIES: DIAGNOSTICS OF ACTIVE GALACTIC NUCLEI AND STAR FORMATION AND CONTRIBUTION TO TOTAL INFRARED LUMINOSITY  

SciTech Connect

We use mid-infrared (MIR) spectroscopy from the Spitzer Infrared Spectrograph to study the nature of star-formation and supermassive black hole accretion for a sample of 65 IR-luminous galaxies at 0.02 < z < 0.6 with F(24 {mu}m) > 1.2 mJy. The MIR spectra cover wavelengths 5-38 {mu}m, spanning the polycyclic aromatic hydrocarbon (PAH) features and important atomic diagnostic lines. Our sample of galaxies corresponds to a range of total IR luminosity, L{sub IR} = L(8-1000 {mu}m) = 10{sup 10}-10{sup 12} L{sub Sun} (median L{sub IR} of 3.0 Multiplication-Sign 10{sup 11} L{sub Sun }). We divide our sample into a subsample of galaxies with Spitzer Infrared Array Camera 3.6-8.0 {mu}m colors indicative of warm dust heated by an active galactic nucleus (AGN; IRAGN) and those galaxies whose colors indicate star-formation processes (non-IRAGN). Compared to the non-IRAGN, the IRAGN show smaller PAH emission equivalent widths, which we attribute to an increase in mid-IR continuum from the AGN. We find that in both the IRAGN and star-forming samples, the luminosity in the PAH features correlates strongly with [Ne II] {lambda}12.8 {mu}m emission line, from which we conclude that the PAH luminosity directly traces the instantaneous star-formation rate (SFR) in both the IRAGN and star-forming galaxies. We compare the ratio of PAH luminosity to the total IR luminosity, and we show that for most IRAGN star-formation accounts for 10%-50% of the total IR luminosity. We also find no measurable difference between the PAH luminosity ratios of L{sub 11.3}/L{sub 7.7} and L{sub 6.2}/L{sub 7.7} for the IRAGN and non-IRAGN, suggesting that AGN do not significantly excite or destroy PAH molecules on galaxy-wide scales. Interestingly, a small subset of galaxies (8 of 65 galaxies) show a strong excess of [O IV] {lambda}25.9 {mu}m emission compared to their PAH emission, which indicates the presence of heavily-obscured AGN, including 3 galaxies that are not otherwise selected as IRAGN. The low PAH emission and low [Ne II] emission of the IRAGN and [O IV]-excess objects imply the IR luminosity of these objects is dominated by processes associated with the AGN. Because these galaxies lie in the ''green valley'' of the optical color-magnitude relation and have low implied SFRs, we argue their hosts have declining SFRs and these objects will transition to the red sequence unless some process restarts their star-formation.

Shipley, Heath V.; Papovich, Casey [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843-4242 (United States); Rieke, George H.; Jannuzi, Buell T.; Weiner, Benjamin [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85719 (United States); Dey, Arjun [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ, 85719 (United States); Moustakas, John, E-mail: heath.shipley@tamu.edu [Department of Physics and Astronomy, Siena College, Loudonville, NY 12211 (United States)

2013-05-20

252

Decontamination of Water Contaminated with Polycyclic Aromatic Hydrocarbons (Pah). I. Action of Chlorine and Ozone on Pah Dissolved in Doubly Distilled and in de-Ionized Water.  

National Technical Information Service (NTIS)

The action of chlorine and ozone on some polynuclear aromatic hydrocarbons (PAH) dissolved in bidistilled water and in deionized water was studied as a part of a larger study on the decontamination of polluted waters by carcinogenic hydrocarbons. The PAH ...

G. S. Sforzolini A. Savino S. Monarca M. N. Lollini

1974-01-01

253

Correlations between PAH bioavailability, degrading bacteria, and soil characteristics during PAH biodegradation in five diffusely contaminated dissimilar soils.  

PubMed

The natural biodegradation of seven polycyclic aromatic hydrocarbons (PAHs) by native microorganisms was studied in five soils from Normandy (France) from diffusely polluted areas, which can also pose a problem in terms of surfaces and amounts of contaminated soils. Bioavailability tests using cyclodextrin-based extractions were performed. The natural degradation of low molecular weight (LMW) PAHs was not strongly correlated to their bioavailability due to their sorption to geosorbents. Conversely, the very low degradation of high molecular weight (HMW) PAHs was partly correlated to their poor availability, due to their sorption on complexes of organic matter and kaolinites or smectites. A principal component analysis allowed us to distinguish between the respective degradation behaviors of LMW and HMW PAHs. LMW PAHs were degraded in less than 2-3 months and were strongly influenced by the relative percentage of phenanthrene-degrading bacteria over total bacteria in soils. HMW PAHs were not significantly degraded, not only because they were less bioavailable but also because of a lack of degrading microorganisms. Benzo[a]pyrene stood apart since it was partly degraded in acidic soils, probably because of a catabolic cooperation between bacteria and fungi. PMID:24671402

Crampon, M; Bureau, F; Akpa-Vinceslas, M; Bodilis, J; Machour, N; Le Derf, F; Portet-Koltalo, F

2014-07-01

254

Removal efficiency of vapour/particulate phase PAHs by using alternative protective respirators in PAHs exposure workers.  

PubMed

Due to the high heat environment in foundry industries, it is difficult for foundry workers to wear masks during their workday. Thus, how to prevent inhaling vapour or the particulate phase of polycyclic aromatic hydrocarbons (PAHs) is important for occupational hazard management. The present study assesses the characteristics of PAHs emission in foundry and plastic industries to evaluate the removal efficiencies of PAHs while workers use alternative personal protective equipment. The highest 1-hydroxypyrene (1-OHP) level was found for workers who used a cotton-fabric face mask (1.19 ?g/g creatinine) and activated-carbon face mask (1.16 ?g/g creatinine), compared to a lower level in workers who wore a surgical face mask (0.27 ?g/g creatinine) and a N95 respirator (0.51 ?g/g creatinine). The urinary 1-OHP in end-of-shift samples correlated to the airborne vapour phase Bapeq, but not for the particulate phase Bapeq in the foundry industry. This is probably because workers wore personal protective equipment that only removed the particulate phase PAH. The current study suggests that future work focus on developing an appropriate and comfortable respirator with high removal efficiency for ultrafine particulates and vapour phase PAHs simultaneously in PAH work environments. PMID:22525483

Chen, Hsiu-Ling; Yang, Chien-Hung; Lin, Ming-Hsiu

2012-06-15

255

Influence of parasitism in controlling the health, reproduction and PAH body burden of petroleum seep mussels  

NASA Astrophysics Data System (ADS)

Petroleum seep mussels are often exposed to high hydrocarbon concentrations in their natural habitat and, thus, offer the opportunity to examine the relationship between parasitism, disease and contaminant exposure under natural conditions. This is the first report on the histopathology of cold-seep mussels. Seep mussels were collected by submersible from four primary sites in the Gulf of Mexico, lease blocks Green Canyon (GC) 184, GC-234, GC-233, and Garden Banks 425 in 550-650 m water depth. Five types of parasites were identified in section: (1) gill "rosettes" of unknown affinity associated with the gill bacteriocytes, (2) gill "inclusions" similar to chlamydia/rickettsia inclusions, (3) extracellular gill ciliates, (4) body "inclusions" that also resemble chlamydial/rickettsial inclusions, and (5) Bucephalus-like trematodes. Comparison to shallow-water mytilids demonstrates that: (1) both have similar parasite faunas; (2) seep mytilids are relatively heavily parasitized; and (3) infection intensities are extremely high in comparison to shallow-water mytilids for Bucephalus and chlamydia/rickettsia. In this study, the lowest prevalence for chlamydia/rickettsia was 67%. Prevalences of 100% were recorded from three populations. Bucephalus prevalence was ?70% in three of 10 populations. The parasite fauna was highly variable between populations. Some important parasites were not observed in some primary sites. Even within primary sites, some important parasites were not observed in some populations. Bucephalus may exert a significant influence on seep mussel population dynamics. Forty percent of the populations in this study are severely reproductively compromised by Bucephalus infection. Only a fraction of petroleum seep mussel populations are maintaining the entire beta-level population structure of this species. Variation in two parasites, gill ciliates and Bucephalus, explained most of the variation in PAH body burden between mussel populations. PAHs are known to be sequestered preferentially in gametic tissue. Bucephalus would be expected to reduce overall body burden, at high infection intensities, by replacing gametic tissue. PAH concentrations exceeded 1 ppm in 4 of 9 populations, a ratio significantly higher than the 8 of 30 mussel locales in the NOAA Mussel Watch Program. Only five Mussel Watch locales exceeded the highest value for a petroleum seep population. Digestive gland and gill tissue atrophy were not significantly correlated with PAH body burden, even though some populations were characterized by body burdens exceeding 1 ppm, suggesting that seep mussels may not be as sensitive to PAH exposure as are some shallow-water mytilid populations.

Powell, Eric N.; Barber, Robert D.; Kennicutt, Mahlon C., II; Ford, Susan E.

1999-12-01

256

Biodegradation of PAHs and PCBs in Soils and Sludges  

NASA Astrophysics Data System (ADS)

Results from a multi-year, pilot-scale land treatment project for PAHs and PCBs biodegradation are evaluated. A mathematical model, capable of describing sorption, sequestration, and biodegradation in a soil/water system, is applied to interpret the efficacy of a sequential active-passive biotreatment process of organic chemicals at remediation sites. To account for the recalcitrance of PAHs and PCBs in soils and sludges during long-term biotreatment, this model comprises a kinetic equation for organic chemical intraparticle sequestration. Model responses were validated by a favorable match to measurements of biodegradation of PAHs and PCBs in a land treatment unit operated by Aluminum Corporation of America Model simulations were performed to predict on-going biodegradation behavior of PAHs and PCBs in land treatment units. Simulation results indicate that complete biostabilization will be achieved when the concentration of reversibly sorbed chemical (SRA) reduces to zero (i.e., undetectable), with a certain amount of irreversibly sequestrated residual chemical (SIA) remaining within the soil particle solid phase. The residual fraction (SIA) tends to lose its original chemical and biological activity, and hence, is much less available, toxic, and mobile than the "free" compounds. Therefore, PAHs and PCBs will leach only slightly, if at all from the treatment site and thus, they constitute no threat to human health or the environment. Biotreatment of PAHs and PCBs can be terminated accordingly. Results from the pilot-scale testing data and model calculations also suggest that a significant fraction (10-30%) of high-molecular-weight PAHs and PCBs could be sequestrated and become unavailable for biodegradation. Bioavailability (large Kd, i.e., slow desorption rate) is the key factor limiting the PAHs degradation. However, both bioavailability and bioactivity, K (as described by Monod kinetics parameters), regulate PCBs biodegradation. The sequential active-passive biotreatment can be a cost-effective approach for remediation of highly hydrophobic organic contaminants. The mathematical model proposed here should be useful in the design and operation of such organic chemical biodegradation processes on remediation sites. Keywords: PAHs; PCBs; Biodegradation; land treatment; Mathematical model and application

Liu, L.; Tindall, J. A.; Zhang, W.

2002-12-01

257

Bioaccumulation, biotransformation and DNA binding of PAHs in feral eel (Anguilla anguilla) exposed to polluted sediments: A field survey  

Microsoft Academic Search

Samples of sediment and eel taken from six sites in Amsterdam with different levels of water pollution were analyzed for 16 parental PAHs. In addition, biliary PAH metabolites and hepatic PAH-DNA adducts were determined in the eel to evaluate biomonitoring techniques for PAH exposure. There was a clear difference between PAH profiles in sediments and eel. Mainly two- and three-ring

Ron van der Oost; H. Heida; K. Satumalay; F. J. Van Schooten; F. Ariese; Nico P. E. Vermeulen

1994-01-01

258

The formation of aromatics and PAH's in laminar flames  

SciTech Connect

The formation of aromatics and PAH's is an important problem in combustion. These compounds are believed to contribute to the formation of soot whose emission from diesel engines is regulated widely throughout the industrial world. Additionally, the United States Environmental Protection Agency regulates the emission of many aromatics and PAH species from stationary industrial burners, under the 1990 Clean Air Act Amendments. The above emission regulations have created much interest in understanding how these species are formed in combustion systems. Much previous work has been done on aromatics and PAH's. The work is too extensive to review here, but is reviewed in Reference 1. A few recent developments are highlighted here. McEnally, Pfefferle and coworkers have studied aromatic, PAH and soot formation in a variety of non-premixed flames with hydrocarbon additives [2-4]. They found additives that contain a C5 ring increase the concentration of aromatics and soot [4]. Howard and coworkers have studied the formation of aromatic and PAH's in low pressure, premixed, laminar hydrocarbon flames. They found the cyclopentadienyl radical to be a key species in naphthalene formation in a fuel-rich, benzene/Ar/O2 flame [5].

Marinov, N M; Pitz, W J; Westbrook, C K

1999-04-01

259

PAH formation in O-rich planetary nebulae  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbons (PAHs) have been observed in O-rich planetary nebulae towards the Galactic bulge. This combination of oxygen-rich and carbon-rich material, known as dual-dust or mixed chemistry, is not expected to be seen around such objects. We recently proposed that PAHs could be formed from the photodissociation of CO in dense tori. In this work, using VISIR/VLT, we spatially resolved the emission of the PAH bands and ionized emission from the [S IV] line, confirming the presence of dense central tori in all the observed O-rich objects. Furthermore, we show that for most of the objects, PAHs are located at the outer edge of these dense/compact tori, while the ionized material is mostly present in the inner parts of these tori, consistent with our hypothesis for the formation of PAHs in these systems. The presence of a dense torus has been strongly associated with the action of a central binary star and, as such, the rich chemistry seen in these regions may also be related to the formation of exoplanets in post-common-envelope binary systems.

Guzman-Ramirez, L.; Lagadec, E.; Jones, D.; Zijlstra, A. A.; Gesicki, K.

2014-06-01

260

Theoretical quantum chemical study of protonated - deuteronated PAHs: Interstellar implications  

NASA Astrophysics Data System (ADS)

Diffuse Interstellar Bands (DIBs) are optical absorption features on the interstellar extinction curve. Ultra-high resolution spectroscopic observations suggest that at least some of these features are due to large molecules. Observational results also reveal that the strengths of the DIBs are not strongly correlated with each other, implying that there must be several carriers. Considering the wide range of interstellar species and the cost and duration of experimental work that is involved to determine the carriers of DIBs, Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TDDFT) calculations offer opportunities to investigate which molecules are suitable for laboratory studies. The widespread presence of Polycyclic Aromatic Hydrocarbons (PAHs) in astrophysical environments is known from observations of the Unidentified Infrared (UIR) emission bands. Since PAHs are stable enough to be present under interstellar conditions, they are good candidates to be the carriers of the DIBs. We report DFT and TDDFT calculations to predict electronic transitions of neutral as well as protonated-deuteronated PAHs with various sites of protonation and deuteronation. The PAH molecules considered for calculation include pyrene, perylene, coronene and heptacene. Compared to their neutral forms, these charged isoelectronic forms of PAHs are predicted to have active transitions in the visible region, which means they are suitable candidates as carriers for some of the DIBs.

Buragohain, Mridusmita; Pathak, Amit; Hammonds, Mark; Sarre, Peter J.

2013-06-01

261

Source apportionment of polycyclic aromatic hydrocarbons (PAHs) into Central Park Lake, New York city, over a century of deposition.  

PubMed

Relative contributions of polycyclic aromatic hydrocarbons (PAHs) from combustion sources of wood, petroleum, and coal were computed in sediments from Central Park Lake in New York City (NY, USA) by chemical mass balance based on several reliable source indicators. These indicators are the ratio of retene to the sum of retene and chrysene, the ratio of 1,7-dimethylphenanthrene (DMP) to 1,7-DMP and 2,6-DMP, and the ratio of fluroanthene to fluroanthene and pyrene. The authors found that petroleum combustion-derived PAH fluxes generally followed the historical consumption data of New York State. Coal combustion-derived PAH flux peaked approximately in the late 1910s, remained at a relatively high level over the next 3 decades, then rapidly declined from the 1950s to the 1960s; according to historical New York State coal consumption data, however, there was a 2-peak trend, with peaks around the early 1920s and the mid-1940s. The 1940s peak was not observed in Central Park Lake, most likely because of the well-documented shift from coal to oil as the major residential heating fuel in New York City during the late 1930s. It was widely believed that the decreased PAH concentrations and fluxes in global sediments during the last century resulted from a major energy shift from coal to petroleum. The data, however, show that this shift occurred from 1945 through the 1960s and did not result in an obvious decline. The sharpest decrease, which occurred in the 1970s was not predominantly related to coal usage but rather was the result of multiple factors, including a decline in petroleum usage largely, the introduction of low sulfur-content fuel in New York City, and the introduction of emission-control technologies. Environ Toxicol Chem 2014;33:985-992. © 2014 SETAC. PMID:24375577

Yan, Beizhan; Bopp, Richard F; Abrajano, Teofilo A; Chaky, Damon; Chillrud, Steven N

2014-05-01

262

Interspecies and interregional comparisons of the chemistry of PAHs and trace elements in mosses Hylocomium splendens (Hedw.) B.S.G. and Pleurozium schreberi (Brid.) Mitt. from Poland and Alaska  

USGS Publications Warehouse

Comparative biogeochemical studies performed on the same plant species in remote areas enable pinpointing interspecies and interregional differences of chemical composition. This report presents baseline concentrations of PAHs and trace elements in moss species Hylocomium splendens and Pleurozium schreberi from the Holy Cross Mountains (south-central Poland) (HCM) and Wrangell-Saint Elias National Park and Preserve (Alaska) and Denali National Park and Preserve (Alaska). Total PAH concentrations in the mosses of HCM were in the range of 473-2970 ??g kg-1 (dry weight basis; DW), whereas those in the same species of Alaska were 80-3390 ??g kg-1 DW. Nearly all the moss samples displayed the similar ring sequence: 3 > 4 > 5 > 6 for the PAHs. The 3 + 4 ring/total PAH ratios show statistically significant differences between HCM (0.73) and Alaska (0.91). The elevated concentrations of PAHs observed in some sampling locations of the Alaskan parks were linked to local combustion of wood, with a component of vehicle particle- and vapor-phase emissions. In HCM, the principal source of PAH emissions has been linked to residential and industrial combustion of coal and vehicle traffic. In contrast to HCM, the Alaskan mosses were distinctly elevated in most of the trace elements, bearing a signature of??the underlying geology. H.??splendens and P. schreberi showed diverse bioaccumulative capabilities of PAHs in all three study areas. ?? 2008 Elsevier Ltd.

Migaszewski, Z. M.; Galuszka, A.; Crock, J. G.; Lamothe, P. J.; Dolegowska, S.

2009-01-01

263

Interstellar PAH Emission in the 11-14 micron Region: New Insights and a Tracer of Ionized PAHs  

NASA Technical Reports Server (NTRS)

The Ames infrared spectral database of isolated, neutral and ionized polycyclic aromatic hydrocarbons (PAHs) shows that aromatic CH out-of-plane bending frequencies are significantly shifted upon ionization. For non-adjacent and doubly-adjacent CH groups, the shift is pronounced and consistently toward higher frequencies. The non-adjacent modes are blueshifted by an average of 27 per cm and the doubly-adjacent modes by an average of 17 per cm. For triply- and quadruply-adjacent CH out-of-plane modes the ionization shifts are more erratic and typically more modest. As a result of these ionization shifts, both the non-adjacent and doubly-adjacent CH out-of-plane modes move out of the regions classically associated with their respective vibrations in neutral PAHs. The doubly-adjacent modes of ionized PAHs tend to fall into the frequency range traditionally associated with the non-adjacent modes, while the non-adjacent modes are shifted to frequencies above those normally attributed to out-of-plane bending vibrations. Consequently, the origin of the interstellar infrared emission feature near 11.2 microns, traditionally attributed to the out-of-plane bending of non-adjacent CH groups on PAHs is rendered ambiguous. Instead, this feature likely reflects contributions from both non-adjacent CH units in neutral PAHs and doubly-adjacent CH units in PAH cations, the dominant charge state in the most energetic emission regions. This greatly relieves the structural constraints placed on the interstellar PAH population by the dominance of the 11.2 micron band in this region and eliminates the necessity to invoke extensive dehydrogenation of the emitting species. Furthermore, these results indicate that the emission between 926 and 904 per cm (10.8 and 11.1 microns) observed in many sources can be unambiguously attributed to the non-adjacent CH out-of-plane bending modes of moderately-sized (fewer than 50 carbon atom) PAH cations making this emission an unequivocal tracer of ionized interstellar PAHs.

Hudgins, Douglas M.; Allamandola, Louis J.; Mead, Susan (Technical Monitor)

1999-01-01

264

Spectroscopic properties of polycyclic aromatic hydrocarbons (PAHs) and astrophysical implications.  

PubMed

PAHs (polycyclic aromatic hydrocarbons) are probably present as a mixture of neutral and ionized species and are responsible for the set of infrared emission bands in the 2-15 microns regions, which are observed in many different objects like reflection and planetary nebulae and external galaxies. PAHs are suggested to be the most abundant free organic molecules and ubiquitous in space. PAHs might also exist in the solid phase, included in interstellar ices in dense clouds. A complex aromatic network is expected on interstellar grains in the diffuse interstellar medium. The existence of an aromatic kerogen-like structure in carbonaceous meteorites and its similarity with interstellar spectra suggests a link between interstellar matter and primitive Solar System bodies. PMID:11541329

d'Hendecourt, L; Ehrenfreund, P

1997-01-01

265

New PAH mode at 16.4 mu m  

NASA Astrophysics Data System (ADS)

The detection of a new 16.4 mu m emission feature in the ISO-SWS spectra of NGC 7023, M17, and the Orion Bar is reported. Previous laboratory experiments measured a mode near this wavelength in spectra of PAHs (Polycyclic Aromatic Hydrocarbons), and so we suggest the new interstellar 16.4 mu m feature could be assigned to low-frequency vibrations of PAHs. The best carrier candidates seem to be PAH molecules containing pentagonal rings. based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: the United Kingdom, France, the Netherlands, Germany), and with the participation of ISAS and NASA.

Moutou, C.; Verstraete, L.; Léger, A.; Sellgren, K.; Schmidt, W.

2000-02-01

266

Spitzer Observations of Extraplanar PAH Emission from Spiral Galaxies  

NASA Astrophysics Data System (ADS)

We present Spitzer/IRAC observations of polycylic aromatic hydrocarbon (PAH) emission from interstellar material in the thick disks of normal spiral galaxies. These data show PAHs to be a common constituent of extraplanar material in spirals. The processes that displace this material from the interstellar disks of these systems do not destroy these very small grains. The dust emission features are present far above the galactic planes, extended up to about 2-4 kpc above the midplanes of the galaxies presented in this work. The total extent for which dust can be traced is about half the extent of the DIG. If it is not a sensitivity effect, this suggests that PAHs may be associated with a cold neutral medium that can not be supported at high z.

Lehner, N.; Howk, J.

267

Levels of PCBs and PAHs in Bahrain soil  

SciTech Connect

The concentration of PCBs in the soil of Bahrain has been determined using GC-ECD. PCBs were detected in only few of the samples analysed. In the contaminated soils, the concentrations of PCBs were in the range of 0.2-72.7 {mu}g/g. These values were compared with published data from industrial countries. Soil samples collected from different parts of the country were also analysed for PAHs using GC-MS. The concentrations of the various PAHs fall within the range 0.01-42.58 {mu}g/g. The samples collected from an aluminum smelter area showed the highest level of PAHs. 19 refs., 2 figs., 2 tabs.

Al-Haddad, A. [Univ. of Bahrain (Bahrain)] [Univ. of Bahrain (Bahrain); Madany, I.M.; Abdullah, F.J. [Arabian Gulf Univ., Bahrain (Bahrain)] [Arabian Gulf Univ., Bahrain (Bahrain)

1993-12-31

268

Improved GC/MS methods for measuring hourly PAH and nitro-PAH concentrations in urban particulate matter  

NASA Astrophysics Data System (ADS)

This study presents two methods for the quantification of nitro-substituted and parent polycyclic aromatic hydrocarbons (NPAH and PAH, respectively), respectively, utilizing large volume injection gas chromatography/mass spectrometry (GC/MS). Both methods (PAH and NPAH, respectively) employed a programmed temperature vaporization injector (PTV) in solvent vent mode, optimized using standard solutions. For the PAH method, the precision of the PTV was comparable to hot splitless injection for exhibiting a percent relative standard deviation (%RSD) consistently below 8% for 100 pg injections. Compound %RSDs for the NPAH method were consistently below 5% using the PTV. Microgram quantities (30-500 ?g) of particulate matter Standard Reference Materials (SRM 1649 and 1650, National Institutes of Standards and Technology) were analyzed to simulate PAH and NPAH quantification on small aerosol mass loadings. The method detection limits from this study suggest PAHs and NPAHs can be easily quantified using low-volume samplers (>5 Lpm) on hourly timescales. In addition, this technique enabled the quantification of 12-h NPAH size distributions in the Baltimore, MD, atmosphere.

Crimmins, Bernard S.; Baker, Joel E.

269

PAH-CALUX, an optimized bioassay for AhR-mediated hazard identification of polycyclic aromatic hydrocarbons (PAHs) as individual compounds and in complex mixtures.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) represent a class of ubiquitously occurring environmental compounds that are implicated in a wide range of toxicological effects. Routine measurement of PAH contamination generally involves chemical analytical analysis of a selected group of representatives, for example, EPA-16, which may result in underestimation of the PAH-related toxicity of a sample. Many high molecular weight PAHs are known ligands of the aryl hydrocarbon receptor (AhR), a nuclear receptor that mediates toxic effects related to these compounds. Making use of this property we developed a PAH CALUX assay, a mammalian, H4IIe- cell-based reporter assay for the hazard identification of total PAH mixtures. The PAH CALUX reporter cell line allows for specific, rapid (4 h exposure time) and reliable quantification of AhR-induced luciferase induction relative to benzo[a]pyrene (BaP), which is used as a positive reference PAH congener. Full dose response relationships with inductions over 100-fold were reached within only 2 h of exposure to BaP. The PAH CALUX is highly sensitive, that is, using a 4 h exposure time, a limit of detection (LOD) of 5.2 × 10(-11) M BaP was achieved, and highly accurate, that is, a repeatability of 5.9% and a reproducibility of 6.6% were established. Screening of a selection of PAHs that were prioritized by the European Union and/or the U.S. Environmental Protection Agency showed that the PAH CALUX bioassay has a high predictability, particularly for carcinogenic PAHs. Experiments with synthetic mixtures and reference materials containing complex PAH mixtures show the suitability of the assay for these types of applications. Moreover, the presented results suggest that application of the PAH CALUX will result in a lower risk of underestimation of the toxicity of a sample than chemical analytical approaches that focus on a limited set of prioritized compounds. PMID:23987121

Pieterse, B; Felzel, E; Winter, R; van der Burg, B; Brouwer, A

2013-10-15

270

Detection of Uv PAHs Fluorescence Bands in Halley's Innermost Coma  

NASA Astrophysics Data System (ADS)

In the innermost coma of P/Halley, at projected distances p<3000 km, the TKS spectrometer on board Vega detected unknown fluorescence bands in the 280-400 nm range. The cometary spectra were compared to laboratory laser-induced fluorescence spectra of PAHs having 2, 3 or 4 benzoid rings. Two PAHs, phenanthrene (C14H10) and pyrene (C16H10) were identified by the presence of three peaks in their individual spectra between 342 and 384 nm. A further examination of the data shows that anthracene (C14H10) is also present in some spectra. The optical axis of TKS scanned an angular sector of Halley's inner coma having its apex at the nucleus. Inside this region, the overall variation of the intensity was ?1/p, which indicates that the polycyclic hydrocarbons are either parent molecules or are released inside the coma by dust particles. As the band intensities are not spatially homogeneous, the PAHs are probably released by dust packs. This first identification of PAHs in a comet was also suggested by the detection of an IR emission at 3.28 ?m in IKS spectra partly due to aromatic polycyclic compounds (Encrenaz et al., A&A 207, 1988, 162-173). More recently, naphthalene, phenanthrene and pyrene were identified in 81P/Wild2 samples (Sandford et al., Science, 2006, 314, 1720-1724). Infrared signatures of PAHs have also been detected at 6.2 and 7.6 ?m in Spitzer spectra of Temple1 ejecta (Lisse et al., Icarus, 2007, 187, 69-86) The presence of PAHs in some comets, also detected in numerous interstellar nebulae gives a strong support to the fact that comets probably have kept trace of the primitive interstellar composition through the early solar system epoch.

Clairemidi, Jacques; Moreels, G.; Bréchignac, P.

2007-10-01

271

Effect of birch (Betula spp.) and associated rhizoidal bacteria on the degradation of soil polyaromatic hydrocarbons, PAH-induced changes in birch proteome and bacterial community.  

PubMed

Two birch clones originating from metal-contaminated sites were exposed for 3 months to soils (sand-peat ratio 1:1 or 4:1) spiked with a mixture of polyaromatic hydrocarbons (PAHs; anthracene, fluoranthene, phenanthrene, pyrene). PAH degradation differed between the two birch clones and also by the soil type. The statistically most significant elimination (p < or = 0.01), i.e. 88% of total PAHs, was observed in the more sandy soil planted with birch, the clearest positive effect being found with Betula pubescens clone on phenanthrene. PAHs and soil composition had rather small effects on birch protein complement. Three proteins with clonal differences were identified: ferritin-like protein, auxin-induced protein and peroxidase. Differences in planted and non-planted soils were detected in bacterial communities by 16S rRNA T-RFLP, and the overall bacterial community structures were diverse. Even though both represent complex systems, trees and rhizoidal microbes in combination can provide interesting possibilities for bioremediation of PAH-polluted soils. PMID:18675498

Tervahauta, Arja I; Fortelius, Carola; Tuomainen, Marjo; Akerman, Marja-Leena; Rantalainen, Kimmo; Sipilä, Timo; Lehesranta, Satu J; Koistinen, Kaisa M; Kärenlampi, Sirpa; Yrjälä, Kim

2009-01-01

272

Biodegradation, bioaccessibility, and genotoxicity of diffuse polycyclic aromatic hydrocarbon (PAH) pollution at a motorway site.  

PubMed

Diffuse pollution of surface soil with polycyclic aromatic hydrocarbons (PAHs) is problematic in terms of the large areas and volumes of polluted soil. The levels and effects of diffuse PAH pollution at a motorway site were investigated. Surface soil was sampled with increasing distance from the asphalt pavement and tested for total amounts of PAHs, amounts of bioaccessible PAHs, total bacterial populations, PAH degrader populations, the potential for mineralization of 14C-PAHs, and mutagenicity. Elevated PAH concentrations were found in the samples taken 1-8 m from the pavement. Soil sampled at greater distances (12-24 m) contained only background levels of PAHs. The total bacterial populations (CFU and numbers of 16S rDNA genes) were similar for all soil samples, whereas the microbial degrader populations (culturable PAH degraders and numbers of PAH dioxygenase genes) were most abundant in the most polluted samples close to the pavement. Hydroxypropyl-beta-cyclodextrin extraction of soil PAHs, as a direct estimate of the bioaccessibility, indicated that only 1-5% of the PAHs were accessible to soil bacteria. This low bioaccessibility is suggested to be due to sorption to traffic soot particles. The increased PAH level close to the pavement was reflected in slightly increased mutagenic activity (1 m, 0.32 +/- 0.08 revertants g(-1) soil; background/ 24 m: 0.08 +/- 0.04), determined by the Salmonella/ microsome assay of total extractable PAHs activated by liver enzymes. The potential for lighter molecular weight PAH degradation in combination with low bioaccessibility of heavier PAHs is proposed to lead to a likely increase in concentration of heavier PAHs over time. These residues are, however, likely to be of low biological significance. PMID:16749696

Johnsen, Anders R; De Lipthay, Julia R; Reichenberg, Fredrik; Sørensen, Søren J; Andersen, Ole; Christensen, Peter; Binderup, Mona-lise; Jacobsen, Carsten S

2006-05-15

273

Biodegradation of PAHs and PCBs in soils and sludges  

USGS Publications Warehouse

Results from a multi-year, pilot-scale land treatment project for PAHs and PCBs biodegradation were evaluated. A mathematical model, capable of describing sorption, sequestration, and biodegradation in soil/water systems, is applied to interpret the efficacy of a sequential active-passive biotreatment process of organic chemicals on remediation sites. To account for the recalcitrance of PAHs and PCBs in soils and sludges during long-term biotreatment, this model comprises a kinetic equation for organic chemical intraparticle sequestration process. Model responses were verified by comparison to measurements of biodegradation of PAHs and PCBs in land treatment units; a favorable match was found between them. Model simulations were performed to predict on-going biodegradation behavior of PAHs and PCBs in land treatment units. Simulation results indicate that complete biostabilization will be achieved when the concentration of reversibly sorbed chemical (S RA) reduces to undetectable levels, with a certain amount of irreversibly sequestrated residual chemical (S IA) remaining within the soil particle solid phase. The residual fraction (S IA) tends to lose its original chemical and biological activity, and hence, is much less available, toxic, and mobile than the "free" compounds. Therefore, little or no PAHs and PCBs will leach from the treatment site and constitutes no threat to human health or the environment. Biotreatment of PAHs and PCBs can be terminated accordingly. Results from the pilot-scale testing data and model calculations also suggest that a significant fraction (10-30%) of high-molecular-weight PAHs and PCBs could be sequestrated and become unavailable for biodegradation. Bioavailability (large K d , i.e., slow desorption rate) is the key factor limiting the PAHs degradation. However, both bioavailability and bioactivity (K in Monod kinetics, i.e., number of microbes, nutrients, and electron acceptor, etc.) regulate PCBs biodegradation. The sequential active-passive biotreatment can be a cost-effective approach for remediation of highly hydrophobic organic contaminants. The mathematical model proposed here would be useful in the design and operation of such organic chemical biodegradation processes on remediation sites. ?? 2007 Springer Science+Business Media B.V.

Liu, L.; Tindall, J. A.; Friedel, M. J.

2007-01-01

274

Radius Ratio  

NSDL National Science Digital Library

This is a set of animations that demonstrates properties of the spherical holes formed when uniform spheres are packed. Cubic, octahedral and tetrahedral packing arrangements may be examined without anything in the holes,and with the repective holes filled. The sizes of the various holes relative to the spheres being packed are shown, which can lead students into an exploration of the radius ratio concept. An example is given of computing the relative size of an octahedral hole.

275

Integrated analytical approach to detailed chemical characterization of coal liquefaction process materials. [Neutral PAH, cyano-PAH, hydroaromatics  

SciTech Connect

Due to the complexity and diversity of chemical species present in the products of coal liquefaction, methods that enable the class-specific separation and analytical determination of a wide concentration range of PAC constituents are of key importance in the detailed characterization of these complex materials. In this paper, an integrated analytical method for the quantitative and qualitative identification of the major chemical classes of coal conversion products has been reviewed. Specifically, techniques for the further elucidation of the neutral PAH, hydroaromatics, amino-PAH, and cyano-PAH have been presented. The end-goal in developing these methods is to provide a comprehensive data base of detailed information that can effectively assist the process engineer and biologist in establishing correlations between chemical composition and observed effects. 7 references, 11 figures, 1 table.

Later, D.W.; Chess, E.K.; Wright, C.W.; Wilson, B.W.

1984-11-01

276

DETECTIONS OF WATER ICE, HYDROCARBONS, AND 3.3 {mu}m PAH IN z {approx} 2 ULIRGs  

SciTech Connect

We present the first detections of the 3 {mu}m water ice and 3.4 {mu}m amorphous hydrocarbon (HAC) absorption features in z {approx} 2 ULIRGs. These are based on deep rest-frame 2-8 {mu}m Spitzer Infrared Spectrograph spectra of 11 sources selected for their appreciable silicate absorption. The HAC-to-silicate ratio for our z {approx} 2 sources is typically higher by a factor of 2-5 than that observed in the Milky Way. This HAC 'excess' suggests compact nuclei with steep temperature gradients as opposed to predominantly host obscuration. Beside the above molecular absorption features, we detect the 3.3 {mu}m polycyclic aromatic hydrocarbon (PAH) emission feature in one of our sources with three more individual spectra showing evidence for it. Stacking analysis suggests that water ice, hydrocarbons, and PAH are likely present in the bulk of this sample even when not individually detected. The most unexpected result of our study is the lack of clear detections of the 4.67 {mu}m CO gas absorption feature. Only three of the sources show tentative signs of this feature at significantly lower levels than has been observed in local ULIRGs. Overall we find that the closest local analogs to our sources, in terms of 3-4 {mu}m color, HAC-to-silicate and ice-to-silicate ratios, as well as low PAH equivalent widths, are sources dominated by deeply obscured nuclei. Such sources form only a small fraction of ULIRGs locally and are commonly believed to be dominated by buried active galactic nuclei (AGNs). Our sample suggests that, in an absolute number, such buried AGNs are at least an order of magnitude more common at z {approx} 2 than today. The presence of PAH suggests that significant levels of star formation are present even if the obscured AGNs typically dominate the power budget.

Sajina, Anna [Physics and Astronomy Department, Haverford College, Haverford, PA, 19041 (United States); Spoon, Henrik [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Yan Lin [IPAC, California Institute of Technology, Pasadena, CA 91125 (United States); Imanishi, Masatoshi [National Astronomical Observatory, 2-21-1, Osawa, Mitaka, Tokyo 181-8588 (Japan); Fadda, Dario [NASAHerschel Space Telescope Center, California Institute of Technology, Pasadena, CA 91125 (United States); Elitzur, Moshe [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States)

2009-09-20

277

A review of airborne polycyclic aromatic hydrocarbons (PAHs) and their human health effects.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) are a large group of organic compounds comprised of two or more fused benzene rings arranged in various configurations. PAHs are widespread environmental contaminants formed as a result of incomplete combustion of organic materials such as fossil fuels. The occurrence of PAHs in ambient air is an increasing concern because of their carcinogenicity and mutagenicity. Although emissions and allowable concentrations of PAHs in air are now regulated, the health risk posed by PAH exposure suggests a continuing need for their control through air quality management. In light of the environmental significance of PAH exposure, this review offers an overview of PAH properties, fates, transformations, human exposure, and health effects (acute and chronic) associated with their emission to the atmosphere. Biomarkers of PAH exposure and their significance are also discussed. PMID:24013021

Kim, Ki-Hyun; Jahan, Shamin Ara; Kabir, Ehsanul; Brown, Richard J C

2013-10-01

278

A TOXICITY ASSESSMENT APPROACH FOR EVALUATION OF IN-SITU BIOREMEDIATION OF PAH CONTAMINATED SEDIMENTS  

EPA Science Inventory

Polycyclic aromatic hydrocarbons (PAHs) represent a group of organic contaminants known for their prevalence and persistence in petroleum-impacted environment such as groundwater, soils and sediments. Many high molecular weight PAHs are suspected carcinogens and the existence of...

279

Increased zooplankton PAH concentrations across hydrographic fronts in the East China Sea.  

PubMed

The Changjiang has transported large quantities of polycyclic aromatic hydrocarbons (PAHs) to the East China Sea (ECS), but information of these pollutants in zooplankton is limited. To understand PAHs pollution in zooplankton in the ECS, total concentrations of PAHs in zooplankton from surface waters were measured. Values of PAHs ranged from 2 to 3500ngm(-3) in the ECS, with highest PAHs levels located at the salinity front between the Changjiang Diluted Water (CDW) and the mid-shelf waters. In contrast, concentrations of zooplankton PAHs in the mid-shelf and outer-shelf waters were significantly lower (2-23ngm(-)(3)) than those in the CDW. These results demonstrate that PAHs are conspicuously accumulated in zooplankton at the salinity front between the CDW and the mid-shelf waters. These higher levels of PAHs in zooplankton at the salinity front may be further biomagnified in marine organisms of higher trophic levels through their feeding activities. PMID:24775063

Hung, Chin-Chang; Ko, Fung-Chi; Gong, Gwo-Ching; Chen, Kuo-Shu; Wu, Jian-Ming; Chiang, Hsin-Lun; Peng, Sen-Chueh; Santschi, Peter H

2014-06-15

280

BIODEGRADATION OF SEDIMENT-BOUND PAHS IN FIELD-CONTAMINATED SEDIMENT  

EPA Science Inventory

The biodegradation of polycyclic aromatic hydrocarbons (PAHs) has been reported to occur under aerobic, sulfate reducing, and denitrifying conditions. PAHs present in contaminated sites, however, are known for their persistence. Most published studies were conducted in systems wh...

281

RISKS TO FISH AND OTHER AQUATIC ORGANISMS FROM PAHS IN NATURAL SYSTEMS  

EPA Science Inventory

Assessing the risks of PAHs to aquatic organisms requires consideration of several factors. First, environmental PAH concentrations must be characterized, including chemical partitioning information important to bioavailability. Second, UV radiation exposures must be evaluated re...

282

ASSAYING PARTICLE-BOUND POLYCYCLIC AROMATIC HYDROCARBONS (PAH) FROM ARCHIVED PM2.5 FILTERS  

EPA Science Inventory

Airborne particulate matter contains numerous organic species, including several polycyclic aromatic hydrocarbons (PAHs) that are known or suspected carcinogens. Existing methods for measuring airborne PAHs are complex and costly, primarily because they are designed to collect...

283

Role of CYP1B1 in PAH-DNA Adduct Formation and Preast Cancer Risk.  

National Technical Information Service (NTIS)

This study investigated the hypothesis that increased exposure to polycyclic aromatic hydrocarbons (PAHs) increases breast cancer risk. PAHs are products of incomplete burning of organic matter and are present in cigarette smoke, ambient air, drinking wat...

A. P. Muller J. Eschiletti M. Caleffi M. D. Sohn M. L. Russell R. Goth-Goldstein

2010-01-01

284

Polycyclic aromatic hydrocarbon (PAH) contamination in the urban topsoils of Shenyang, China  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs) in the surface urban soils of Shenyang in Northeastern China were investigated. The total concentration of the PAHs ranged from 0.09 to 8.35 mg kg, with an average value of 1.51 ± 1.64 mg kg. 3–5-ring PAHs accounted for 90% of total PAHs. The functional areas, such as the industrial regions (4.95 mg kg) and main roads (1.56 mg kg),

Yuebing Sun; Guohong Sun; Qixing Zhou; Yingming Xu; Lin Wang; Xuefeng Liang; Yang Sun; Xu Qin

2012-01-01

285

Emissions of polycyclic aromatic hydrocarbons (PAHs) from the pyrolysis of scrap tires  

Microsoft Academic Search

This work investigated the PAHs generated in a waste-tire pyrolysis process and the PAHs removal by a wet scrubber (WSB) and a flare. IND, DBA, and BaP were found to dominate in the powders of scrap tires before the pyrolysis. The PAHs in the carbon blacks formed in the pyrolysis were mainly 2-, 3-, 6-, and 7-ring PAHs. Nap was

Shui-Jen Chen; Hung-Bin Su; Juu-En Chang; Wen-Jhy Lee; Kuo-Lin Huang; Lien-Te Hsieh; Yi-Chu Huang; Wen-Yinn Lin; Chih-Chung Lin

2007-01-01

286

Influence of smoking parameters on the concentration of polycyclic aromatic hydrocarbons (PAHs) in Danish smoked fish  

Microsoft Academic Search

A new method for the analysis of 25 polycyclic aromatic hydrocarbon (PAH) compounds in fish was developed, validated, and used for the quantification of PAHs in 180 industrially smoked fish products. The method included pressurized liquid extraction, gel-permeation chromatography (Bio-beads S-X3), solid-phase extraction (silica gel), and gas chromatography-mass spectrometry analysis. The sum concentration of 25 PAHs (?PAH25) was highest in

L. Duedahl-Olesen; J. H. Christensen; A. Højgård; K. Granby; M. Timm-Heinrich

2010-01-01

287

Angular motion of a PAH molecule in interstellar environment  

NASA Technical Reports Server (NTRS)

Polycyclic aromatic hydrocarbon (PAH) molecules have recently been proposed as an important and hitherto undetected component of the Interstellar Medium (ISM). The theory was based on an explanation of the Unidentified IR Emission Bands by Leger et al. It has already led to a verified prediction on extended galactic and extragalactic emissions measured by IRAS, or by a recent balloon borne experiment. The physics that rules the motion of such molecules in the ISM was studied, taking into account their coupling with the ambient gas, the radiation field (absorption and emission) and the static magnetic field. This is important for many implications of the PAH theory such as the radio emission by these molecules or the expected polarization of their IR emission. A reflection nebulae is considered where the situation is rather well known. Every day life of a mean PAH molecule in such a region is as follows: every 3 hrs a UV photon is absorbed heating the molecule to a thousand degs; the temperature decay due to cooling by IR emission follows then within a few seconds. A collision with a molecule of gas occurs typically once a week, while an H atom is ejected or captured at the same rate. A typical cooling cycle after a heat impulse is given. The PAH molecules studied as representative of the family has typically 50 atoms, a radius of 4.5 A, is circular and has a molecular mass of M = 300; its permanent dipole moment is 3 Debye.

Rouan, D.; Leger, Alain; Omont, A.; Giard, Martin

1989-01-01

288

PAHs molecules and heating of the interstellar gas  

NASA Technical Reports Server (NTRS)

Until now it has remained difficult to account for the rather high temperatures seen in many diffuse interstellar clouds. Various heating mechanisms have been considered: photoionization of minor species, ionization of H by cosmic rays, and photoelectric effect on small grains. Yet all these processes are either too weak or efficient under too restricting conditions to balance the observed cooling rates. A major heat source is thus still missing in the thermal balance of the diffuse gas. Using photoionization cross sections measured in the lab, it was shown that in order to balance the observed cooling rates in cold diffuse clouds (T approx. 80 K) the PAHs would have to contain 15 percent of the cosmic abundance of carbon. This value does not contradict the former estimation of 6 percent deduced from the IR emission bands since this latter is to be taken as a lower limit. Further, it was estimated that the contribution to the heating rate due to PAH's in a warm HI cloud, assuming the same PAH abundance as for a cold HI cloud, would represent a significant fraction of the value required to keep the medium in thermal balance. Thus, photoionization of PAHs might well be a major heat source for the cold and warm HI media.

Verstraete, Laurent; Leger, Alain; Dhendecourt, Louis B.; Dutuit, O.; Defourneau, D.

1989-01-01

289

Human Exposures to PAHs: an Eastern United States Pilot Study  

EPA Science Inventory

Personal exposure monitoring for select polycyclic aromatic hydrocarbons (PAHs) was performed as part of the National Human Exposure Assessment Survey (NHEXAS) Pilot Study in Baltimore, MD and in four surrounding counties (NHEXAS-Maryland). An objective of this effort was to esta...

290

Measurement of polycyclic aromatic hydrocarbon (PAHs) in interplanetary dust particles  

NASA Technical Reports Server (NTRS)

We report here the first definitive measurements of specific organic molecules (polycyclic aromatic hydrocarbons (PAH's)) in interplanetary dust particles (IDP's). An improved version of the microbeam-two-step laser mass spectrometer was used for the analysis. Two IDP's gave similar mass spectra showing an abundance of PAH's. Control samples, including particles of probable terrestrial origin from the same stratospheric collector, gave either null results or quite different spectra. We conclude that the PAH's are probably indigenous to the IDP's and are not terrestrial contaminants. The instrument used to study the particles is a two-step laser mass spectrometer. Constituent neutral molecules of the sample are first desorbed with a pulsed infrared laser beam focussed to 40 micrometers. In the second step, PAH's in the desorbed plume are preferentially ionized by a pulsed UV laser beam. Resulting ions produced by resonant absorption are extracted into a reflectron time-of-flight mass spectrometer. This instrument has high spatial resolution, high ion transmission, unlimited mass range, and multichannel detection of all ion masses from a single laser shot.

Clemett, S. J.; Maechling, C. R.; Zare, R. N.; Swan, P. D.; Walker, R. M.

1993-01-01

291

PAH EXPOSURES OF PRESCHOOL CHILDREN AND THEIR ADULT CAREGIVERS  

EPA Science Inventory

The results of four small studies of the polycyclic aromatic hydrocarbon (PAH) exposures of preschool children in low-income families from the Piedmont area of North Carolina were combined to allow comparisons of the total exposures of the children and their adult caregivers. I...

292

MULTIMEDIA CONCENTRATIONS OF PAH IN SEVERAL DAY CARE CENTERS  

EPA Science Inventory

Concentrations of polycyclic aromatic hydrocarbons were measured in nine day care centers in the spring of 1997. Indoor and outdoor air, food and beverages, indoor dust, and outdoor play area soil were sampled. The mean sums of 20 target PAH concentrations were 265 and 199 ng...

293

PAH emissions from combustion of coal liquids in industrial furnace  

Microsoft Academic Search

The possible environmental impact of substituting fuel oils derived from coal instead of petroleum was investigated using an industrial furnace. Emphasis was placed on the emissions of polynuclear aromatic hydrocarbons (PAH). The nonpetroleum fuel oil (ECLP-SS) was produced from Texas lignite coal by the Exxon Donor Solvent Process at the Exxon Coal Liquefaction Pilot Plant. The effects of furnace loading

R. M. Schirmer; M. D. Gill; D. A. Nickeson

1983-01-01

294

Understanding the Complexity and Strategic Evolution in PAH Remediation Research  

Microsoft Academic Search

The development and improvement of society through industrialization and urbanization comes with the cost of consistent deterioration and degradation of the natural environment through generation of toxic and hazardous pollutants. Polycyclic aromatic compounds (PAHs) are a major class of such persistent organic pollutants, posing serous threat to terrestrial and aquatic ecosystems due to their intrinsic low aqueous solubility, higher binding

Biswanath Mahanty; Kannan Pakshirajan; Veeranki Venkata Dasu

2011-01-01

295

Temporal variations in PAH concentrations in Quercus ilex L. (holm oak) leaves in an urban area.  

PubMed

Temporal variations of polycyclic aromatic hydrocarbon (PAH) concentrations in leaves of a Mediterranean evergreen oak, Quercus ilex L., were investigated in order to assess the suitability of this species to biomonitor PAH air contamination. Leaf samples were collected at six sites of the urban area of Naples (Italy) and at a control site in the Vesuvius National Park, in May and September 2001, and in January and May 2002. PAH extraction was conducted by sonication in dichloromethane-acetone and quantification by GC-MS. In winter, leaf total PAH concentrations showed, at all the urban sites, values 2-fold higher than in all the other samplings, reflecting the temporal trend reported for PAH air contamination in the Naples urban area. Moreover, leaf PAH concentrations showed, at all the urban sites, a decrease in May 2002 after the winter accumulation. At the control site leaf PAH concentrations showed lower values and smaller temporal variations than at the urban sites. The findings support the suitability of Q. ilex leaves to monitor temporal variations in PAH contamination. The highest winter concentrations of total PAHs were due to the medium molecular weight PAHs that increased with respect to both low and high molecular weight PAHs. The medium molecular weight PAHs showed the same temporal trend both at the urban and remote sites. PMID:16182861

De Nicola, Flavia; Maisto, Giulia; Prati, Maria Vittoria; Alfani, Anna

2005-10-01

296

Emissions of polycyclic aromatic hydrocarbons (PAHs) from the pyrolysis of scrap tires  

NASA Astrophysics Data System (ADS)

This work investigated the PAHs generated in a waste-tire pyrolysis process and the PAHs removal by a wet scrubber (WSB) and a flare. IND, DBA, and BaP were found to dominate in the powders of scrap tires before the pyrolysis. The PAHs in the carbon blacks formed in the pyrolysis were mainly 2-, 3-, 6-, and 7-ring PAHs. Nap was the most predominant water-phase PAH in the WSB effluent. About 40% of the water-phase total-PAHs in the WSB effluent were contributed by nine carcinogenic PAHs. NaP, IND, and COR displayed higher mean gas- and particulate-phase concentrations than the other PAHs in the flare exhaust. The mean removal efficiencies of individual PAHs, total-PAHs, and high carcinogenic BaP+IND+DBA were 39.1-90.4%, 76.2%, and 84.9%, respectively for the WSB. For the flare, the mean removal efficiencies of gaseous, particulate, and combined (gaseous+particulate) total-PAHs were 59.8%, 91.2%, and 66.8%, respectively, whereas the removal efficiencies were 91.0%, 80.1%, and 89.1%, respectively for the total-BaPeq. However, the gaseous BaA displayed a negative mean removal efficiency. The total PAH emission rate and factor estimated for the scrap tire pyrolysis plant were 42.3 g d -1 and 4.00 mg kg-tire -1, respectively.

Chen, Shui-Jen; Su, Hung-Bin; Chang, Juu-En; Lee, Wen-Jhy; Huang, Kuo-Lin; Hsieh, Lien-Te; Huang, Yi-Chu; Lin, Wen-Yinn; Lin, Chih-Chung

297

Comparison of PAH Biodegradation and Desorption Kinetics During Bioremediation of Aged Petroleum Hydrocarbon Contaminated Soils  

Microsoft Academic Search

It is commonly assumed that mass-transfer limitations are the cause for slow and incomplete biodegradation of PAHs in aged soils. In order to test this hypothesis, the biodegradation rate and the abiotic release rate were measured and compared for selected PAHs in three different soils. It was found that PAH biodegradation was not mass-transfer limited during slurry bioremediation of an

Michael H. Huesemann; Tom S. Hausmann; Timothy J. Fortman

2000-01-01

298

Predicting a clinical\\/biochemical phenotype for PKU\\/MHP patients with PAH gene mutations  

Microsoft Academic Search

Phenylketonuria (PKU) and mild hyperphenylalaninemia (MHP) are allelic disorders caused by mutations in the gene encoding\\u000a phenylalanine hydroxylase (PAH). In this study, a total of 218 independent PAH chromosomes (109 unrelated patients with PKU residing in Lithuania) were investigated. All 13 exons of the PAH gene of all PKU probands were scanned for DNA alterations by denaturing gradient gel electrophoresis

J. Kasnauskien?; L. Cimbalistien?; V. Ku?inskas

2008-01-01

299

Chemical and stable carbon isotopic characterization for PAHs in aerosol emitted from two indoor sources  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs) are with great environmental concerns due to their toxic, mutagenic, and carcinogenic properties. The harmful effects caused by PAHs emitted from indoor sources may be more direct and serious. In this study, PAHs in aerosol from two typical indoor sources, the cooking fume (CF) and environmental tobacco smoke (ETS) were collected by simulation emission in a

Liwen Zhang; Zhipeng Bai; Yan You; Jianhui Wu; Yinchang Feng; Tan Zhu

2009-01-01

300

PAH depositional history and sources in recent sediment core from Ukwa Ibom Lake, S. E. Nigeria.  

PubMed

Analyses of recent sediment core from the Ukwa Ibom Lake show evidence of aquatic production, terrigenous, combustion and petroleum inputs. Total organic carbon/total nitrogen values (>10) for the sediments indicate greater wash-in of land-plant organic matter relative to algal production. The characteristic combustion ratios, fluoranthene/fluoranthene + pyrene (>0.50), anthracene/anthracene + phenanthrene (>0.10), benzo(a)anthracene/benzo(a)anthracene + chrysene (>0.35) as well as 1,7/1,7 + 2,6-dimethylphenanthrene (>0.70) were observed for the top section only. These results coincided with the most recent pave-road extension exercise involving tree logging and burning of bush. The highest total PAH concentration (91.13 ng/g dry weight (dw)) observed for the bottom section coincided with the period of inhabitation of the lake catchments (~5 decades ago) when discharge to the Lake water of domestic sewage and mill waste water were prevalent. The regular decline in total PAH concentrations upcore is a reflection of the ban placed on indiscriminate dumping of wastes following relocation of the inhabitants of the catchments. Besides the local depositional history, the irregular decrease in unresolved complex mixture (UCM) profiles suggests regional contaminant influx from the adjacent upper Cross River estuary, especially during intense rainfall event. The non-uniformity in methylphenanthrene indices (MPI-1 and MPI-2) shows evidence of importation and utilization of petroleum products of different thermal maturity histories into the Nigerian economy. PMID:22821212

Oyo-Ita, O E; Oyo-Ita, I O

2013-04-01

301

POLYCYCLIC AROMATIC HYDROCARBON AND EMISSION LINE RATIOS IN ACTIVE GALACTIC NUCLEI AND STARBURST GALAXIES  

SciTech Connect

We study the polycyclic aromatic hydrocarbon (PAH) bands, ionic emission lines, and mid-infrared continuum properties in a sample of 171 emission line galaxies taken from the literature plus 15 new active galactic nucleus (AGN) Spitzer spectra. We normalize the spectra at {lambda} = 23 {mu}m and grouped them according to the type of nuclear activity. The continuum shape steeply rises for longer wavelengths and can be fitted with a warm blackbody distribution of T {approx} 150-300 K. The brightest PAH spectral bands (6.2, 7.7, 8.6, 11.3, and 12.7 {mu}m) and the forbidden emission lines of [Si II] 34.8 {mu}m, [Ar II] 6.9 {mu}m, [S III] 18.7 and 33.4 {mu}m were detected in all the starbursts and in {approx}80% of the Seyfert 2. Taking under consideration only the PAH bands at 7.7 {mu}m, 11.3 {mu}m, and 12.7 {mu}m, we find that they are present in {approx}80% of the Seyfert 1, while only half of this type of activity show the 6.2 {mu}m and 8.6 {mu}m PAH bands. The observed intensity ratios for neutral and ionized PAHs (6.2 {mu}m/7.7 {mu}m x 11.3 {mu}m/7.7 {mu}m) were compared to theoretical intensity ratios, showing that AGNs have higher ionization fraction and larger PAH molecules ({>=}180 carbon atoms) than SB galaxies. The ratio between the ionized (7.7 {mu}m) and the neutral PAH bands (8.6 {mu}m and 11.3 {mu}m) are distributed over different ranges for AGNs and SB galaxies, suggesting that these ratios could depend on the ionization fraction, as well as on the hardness of the radiation field. The ratio between the 7.7 {mu}m and 11.3 {mu}m bands is nearly constant with the increase of [Ne III]15.5 {mu}m/[Ne II] 12.8 {mu}m, indicating that the fraction of ionized to neutral PAH bands does not depend on the hardness of the radiation field. The equivalent width of both PAH features show the same dependence (strongly decreasing) with [Ne III]/[Ne II], suggesting that the PAH molecules, emitting either ionized (7.7 {mu}m) or neutral (11.3 {mu}m) bands, may be destroyed with the increase of the hardness of the radiation field.

Sales, Dinalva A.; Pastoriza, M. G.; Riffel, R., E-mail: dinalva.aires@ufrgs.b, E-mail: pastoriza@ufrgs.b, E-mail: riffel@ufrgs.b [Departamento de Astronomia, Universidade Federal do Rio Grande do Sul. Av. Bento Goncalves 9500, Porto Alegre, RS (Brazil)

2010-12-10

302

Plasma processing of interstellar PAHs into solar system kerogen  

NASA Technical Reports Server (NTRS)

Processes resulting in the formation of hydrocarbons of carbonaceous chondrites and the identity of the interstellar molecular precursors involved are an objective of investigations into the origin of the solar system and perhaps even life on earth. We have combined the resources and experience of an astronomer and physicists doing laboratory simulations with those of a chemical expert in the analysis of meteoritic hydrocarbons, in a project that investigated the conversion of polycyclic aromatic hydrocarbons (PAHs) formed in stellar atmospheres into alkanes found in meteorites. Plasma hydrogenation has been found in the University of Alabama at Birmingham Astrophysics Laboratory to produce from the precursor PAH naphthalene, a new material having an IR absorption spectrum (Lee, W. and Wdowiak, T.J., Astrophys. J. 417, L49-L51, 1993) remarkably similar to that obtained at Arizona State University of the benzene-methanol extract of the Murchison meteorite (Cronin, J.R. and Pizzarello, S., Geochim. Cosmochim. Acta 54, 2859-2868, 1990). There are astrophysical and meteoritic arguments for PAH species from extra-solar sources being incorporated into the solar nebula, where plasma hydrogenation is highly plausible. Conversion of PAHs into alkanes could also have occurred in the interstellar medium. The synthesis of laboratory analogs of meteoritic hydrocarbons through plasma hydrogenation of PAH species is underway, as is chemical analysis of those analogs. The objective is to clarify this heretofore uninvestigated process and to understand its role during the origin of the solar system as a mechanism of production of hydrocarbon species now found in meteorites. Results have been obtained in the form of time-of-flight spectroscopy and chemical analysis of the lab analog prepared from naphthalene.

Wdowiak, T. J.; Lee, W.; Cronin, J.; Beegle, L. W.; Robinson, M. S.

1995-01-01

303

Plasma processing of interstellar PAHs into solar system kerogen.  

PubMed

Processes resulting in the formation of hydrocarbons of carbonaceous chondrites and the identity of the interstellar molecular precursors involved are an objective of investigations into the origin of the solar system and perhaps even life on earth. We have combined the resources and experience of an astronomer and physicists doing laboratory simulations with those of a chemical expert in the analysis of meteoritic hydrocarbons, in a project that investigated the conversion of polycyclic aromatic hydrocarbons (PAHs) formed in stellar atmospheres into alkanes found in meteorites. Plasma hydrogenation has been found in the University of Alabama at Birmingham Astrophysics Laboratory to produce from the precursor PAH naphthalene, a new material having an IR absorption spectrum (Lee, W. and Wdowiak, T.J., Astrophys. J. 417, L49-L51, 1993) remarkably similar to that obtained at Arizona State University of the benzene-methanol extract of the Murchison meteorite (Cronin, J.R. and Pizzarello, S., Geochim. Cosmochim. Acta 54, 2859-2868, 1990). There are astrophysical and meteoritic arguments for PAH species from extra-solar sources being incorporated into the solar nebula, where plasma hydrogenation is highly plausible. Conversion of PAHs into alkanes could also have occurred in the interstellar medium. The synthesis of laboratory analogs of meteoritic hydrocarbons through plasma hydrogenation of PAH species is underway, as is chemical analysis of those analogs. The objective is to clarify this heretofore uninvestigated process and to understand its role during the origin of the solar system as a mechanism of production of hydrocarbon species now found in meteorites. Results have been obtained in the form of time-of-flight spectroscopy and chemical analysis of the lab analog prepared from naphthalene. PMID:11540308

Wdowiak, T J; Lee, W; Cronin, J; Beegle, L W; Robinson, M S

1995-01-01

304

Nitration of particle-associated PAHs and their derivatives (nitro-, oxy-, and hydroxy-PAHs) with NO 3 radicals  

NASA Astrophysics Data System (ADS)

The heterogeneous reactions of typical polycyclic aromatic hydrocarbons (PAHs) and their derivatives (nitro-, oxy-, and hydroxy-PAHs) adsorbed on azelaic acid particles with NO 3 radicals are investigated using a flow-tube reactor coupled to a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS). The mono-nitro-, di-nitro-, and poly-nitro-products from successive nitro-substitution reactions of PAHs and their derivatives are observed in real time with VUV-ATOFMS. 9-Nitroanthracene, anthraquinone, anthrone, 9,10-dinitroanthracene, 2-, 4-, and 9-nitrophenanthrene, 1-nitropyrene, 1,3-, 1,6-, and 1,8-dinitropyrene, 7-nitrobenzo[ a]anthracene, and benzo[ a]anthracene-7,12-dione are identified by GC/MS analysis of the reaction products of PAHs and their derivatives coated on the inner bottom surface of the conical flasks with NO 3 radicals. Other oxygenated products are tentatively assigned. 1-Nitropyrene is the only mono-nitrated product detected in the reaction of surface-bound pyrene with gas-phase NO 3 radicals. This phenomenon is different from what has been observed in previous studies of the gas-phase pyrene nitration, showing that 2-nitropyrene is the sole nitration product. The experimental results may reveal the discrepancies between the heterogeneous and homogeneous nitrations of pyrene.

Zhang, Yang; Yang, Bo; Gan, Jie; Liu, Changgeng; Shu, Xi; Shu, Jinian

2011-05-01

305

The proportion of tetrahydrobiopterin deficiency and PAH gene deficiency variants among cases with hyperphenyalaninemia in Western Iran  

PubMed Central

BACKGROUND: Defects either in phenylalanine hydroxylase (PheOH) or in the production and recycling of its cofactor (tetrahydrobiopterin [BH4]) are the causes of primary hyperphenylalaninemia (HPA). The aim of our study was to investigate the current status of different variants of HPA Kurdish patients in Kermanshah province, Iran. MATERIALS AND METHODS: From 33 cases enrolled in our study, 32 were identified as HPA patients. Reassessing of pre-treatment phenylalanine concentrations and the analysis of urinary pterins was done by high-performance liquid chromatography method. RESULTS: A total of 30 patients showed PAH deficiency and two patients were diagnosed with BH4 deficiency (BH4/HPA ratio = 6.25%). Both of these two BH4-deficient patients were assigned to severe variant of dihydropteridine reductase (DHPR) deficiency. More than 75% of patients with PAH deficiency classified as classic phenylketonuria (PKU) according their levels of pre-treatment phenylalanine concentrations. CONCLUSION: Based on the performed study, we think that the frequency of milder forms of PKU is higher than those was estimated before and/or our findings here. Furthermore, the frequency of DHPR deficiency seems to be relatively high in our province. Since the clinical symptoms of DHPR deficiency are confusingly similar to that of classic PKU and its prognosis are much worse than classical PKU and cannot be solely treated with the PKU regime, our pilot study support that it is crucial to set up screening for BH4 deficiency, along with PAH deficiency, among all HPA patients diagnosed with HPA.

Moradi, Keyvan; Alibakhshi, Reza; Khatami, Shohreh

2013-01-01

306

Fungal diagnostics.  

PubMed

Early diagnosis of fungal infection is critical to effective treatment. There are many impediments to diagnosis such as a diminishing number of clinical mycologists, cost, time to result, and requirements for sensitivity and specificity. In addition, fungal diagnostics must meet the contrasting needs presented by the increasing diversity of fungi found in association with the use of immunosuppressive agents in countries with high levels of medical care and the need for diagnostics in resource-limited countries where large numbers of opportunistic infections occur in patients with AIDS. Traditional approaches to diagnosis include direct microscopic examination of clinical samples, histopathology, culture, and serology. Emerging technologies include molecular diagnostics and antigen detection in clinical samples. Innovative new technologies that use molecular and immunoassay platforms have the potential to meet the needs of both resource-rich and resource-limited clinical environments. PMID:24692193

Kozel, Thomas R; Wickes, Brian

2014-01-01

307

Polycyclic Aromatic Hydrocarbon (PAH) Exposure and DNA Adduct Semi-Quantitation in Archived Human Tissues  

PubMed Central

Polycyclic aromatic hydrocarbons (PAHs) are combustion products of organic materials, mixtures of which contain multiple known and probable human carcinogens. PAHs occur in indoor and outdoor air, as well as in char-broiled meats and fish. Human exposure to PAHs occurs by inhalation, ingestion and topical absorption, and subsequently formed metabolites are either rendered hydrophilic and excreted, or bioactivated and bound to cellular macromolecules. The formation of PAH-DNA adducts (DNA binding products), considered a necessary step in PAH-initiated carcinogenesis, has been widely studied in experimental models and has been documented in human tissues. This review describes immunohistochemistry (IHC) studies, which reveal localization of PAH-DNA adducts in human tissues, and semi-quantify PAH-DNA adduct levels using the Automated Cellular Imaging System (ACIS). These studies have shown that PAH-DNA adducts concentrate in: basal and supra-basal epithelium of the esophagus, cervix and vulva; glandular epithelium of the prostate; and cytotrophoblast cells and syncitiotrophoblast knots of the placenta. The IHC photomicrographs reveal the ubiquitous nature of PAH-DNA adduct formation in human tissues as well as PAH-DNA adduct accumulation in specific, vulnerable, cell types. This semi-quantative method for PAH-DNA adduct measurement could potentially see widespread use in molecular epidemiology studies.

Pratt, M. Margaret; John, Kaarthik; MacLean, Allan B.; Afework, Senait; Phillips, David H.; Poirier, Miriam C.

2011-01-01

308

Behaviour of different lichen species as biomonitors of air pollution by PAHs in natural ecosystems.  

PubMed

Six different species of lichens (Parmelia sulcata Tayl., Evernia prunastri (L.) Ach., Ramalina farinacea, Pseudevernia furfuracea (L.) Zopf., Usnea sp. and Lobaria pulmonaria (Schreb.) Hoffm.) were collected in two mountain valleys in Central Pyrenees: the Aspe and Aragon valleys. Two multivariate techniques have been applied with different purposes, ANOVA and Discriminant Analysis (DA), to evaluate the data. The PAHs spatial distribution was studied in the three more abundant and widespread species in the area: P. sulcata, E. prunastri (L.) Ach. and R. farinacea in terms of total PAHs, PAHs related to the combustion processes and toxicity. Different behaviour of each lichen species to trap PAHs was found, being P. sulcata the best one to monitor the most persistent PAHs of pyrogenic origin and E. prunastri the most appropriate to provide information about pyrogenic and petrogenic PAHs. Traffic was the most relevant influence in PAHs bioaccumulation in lichen species. PMID:21822516

Blasco, María; Domeño, Celia; López, Patricia; Nerín, Cristina

2011-09-01

309

Impact of oxidation process on polycyclic aromatic hydrocarbon (PAH) content in bitumen.  

PubMed

This study investigated the impact of the oxidation process on the concentration of polycyclic aromatic hydrocarbons (PAH) in blown bitumen and identified some key contributing parameters. The U.S. Environmental Protection Agency's PAH list was used for this study. PAHs are considered a good toxicological marker, and measurement of PAHs in bitumen can be performed easily. The results of PAH content in blown bitumen and the corresponding feedstock was determined from the limit of detection up to 120 mg/kg for 24 samples. Compared to PAH levels in coal tar pitch, PAH levels in bitumen are very low. Measurements were performed by three laboratories using different methods to allow robust conclusions. The results highlight the difficulties in measuring PAHs in bitumen with accuracy for values below 30 mg/kg; therefore the discussion is based on summary statistics by adding concentrations of PAHs with common ring sizes. Incorporation of flux oil in the feed of the blowing bitumen unit tends to increase PAH content in feed stock and in blown bitumen, particularly the 4- to 6-ring PAHs, which are the most carcinogenic as identified by an animal skin painting test. The amount of PAH content from blown bitumen with flux oil can be at least three times higher than the amount in blown bitumen without flux oil, depending on the quality and quantity of the flux oil used. This study shows that the blowing process does not produce PAHs in bitumen. Conversely, it appears to reduce them in the final product. Close to 10 to 30% of PAHs are probably stripped from the liquid phase of bitumen during the blowing operation. PMID:23767962

Bolliet, Christophe; Juery, Catherine; Thiebaut, Benoit

2013-01-01

310

PAH volatilization following application of coal-tar-based pavement sealant  

NASA Astrophysics Data System (ADS)

Coal-tar-based pavement sealants, a major source of PAHs to urban water bodies, have recently been identified as a source of volatile PAHs to the atmosphere. We tracked the volatilization of PAHs for 1 year after application of a coal-tar-based pavement sealant by measuring gas-phase PAH concentrations above the pavement surface and solid-phase PAH concentrations in sealant scraped from the surface. Gas-phase concentrations at two heights (0.03 and 1.28 m) and wind speed were used to estimate volatilization flux. The sum of the concentrations of eight frequently detected PAHs (?PAH8) in the 0.03-m sample 1.6 h after application (297,000 ng m-3) was about 5000 times greater than that previously reported for the same height above unsealed parking lots (66 ng m-3). Flux at 1.6 h after application was estimated at 45,000 ?g m-2 h-1 and decreased rapidly during the 45 days after application to 160 ?g m-2 h-1. Loss of PAHs from the adhered sealant also was rapid, with about a 50% decrease in solid-phase ?PAH8 concentration over the 45 days after application. There was general agreement, given the uncertainties, in the estimated mass of ?PAH8 lost to the atmosphere on the basis of air sampling (2-3 g m-2) and adhered sealant sampling (6 g m-2) during the first 16 days after application, translating to a loss to the atmosphere of one-quarter to one-half of the PAHs in the sealcoat product. Combining the estimated mass of ?PAH8 released to the atmosphere with a national-use estimate of coal-tar-based sealant suggests that PAH emissions from new coal-tar-based sealcoat applications each year (˜1000 Mg) are larger than annual vehicle emissions of PAHs for the United States.

Van Metre, Peter C.; Majewski, Michael S.; Mahler, Barbara J.; Foreman, William T.; Braun, Christopher L.; Wilson, Jennifer T.; Burbank, Teresa L.

2012-05-01

311

PAH volatilization following application of coal-tar-based pavement sealant  

USGS Publications Warehouse

Coal-tar-based pavement sealants, a major source of PAHs to urban water bodies, have recently been identified as a source of volatile PAHs to the atmosphere. We tracked the volatilization of PAHs for 1 year after application of a coal-tar-based pavement sealant by measuring gas-phase PAH concentrations above the pavement surface and solid-phase PAH concentrations in sealant scraped from the surface. Gas-phase concentrations at two heights (0.03 and 1.28 m) and wind speed were used to estimate volatilization flux. The sum of the concentrations of eight frequently detected PAHs (?PAH8) in the 0.03-m sample 1.6 h after application (297,000 ng m-3) was about 5000 times greater than that previously reported for the same height above unsealed parking lots (66 ng m-3). Flux at 1.6 h after application was estimated at 45,000 ?g m-2 h-1 and decreased rapidly during the 45 days after application to 160 ?g m-2 h-1. Loss of PAHs from the adhered sealant also was rapid, with about a 50% decrease in solid-phase ?PAH8 concentration over the 45 days after application. There was general agreement, given the uncertainties, in the estimated mass of ?PAH8 lost to the atmosphere on the basis of air sampling (2–3 g m-2) and adhered sealant sampling (6 g m-2) during the first 16 days after application, translating to a loss to the atmosphere of one-quarter to one-half of the PAHs in the sealcoat product. Combining the estimated mass of ?PAH8 released to the atmosphere with a national-use estimate of coal-tar-based sealant suggests that PAH emissions from new coal-tar-based sealcoat applications each year (~1000 Mg) are larger than annual vehicle emissions of PAHs for the United States.

Van Metre, Peter C.; Majewski, Michael S.; Mahler, Barbara J.; Foreman, William T.; Braun, Christopher L.; Wilson, Jennifer T.; Burbank, Teresa L.

2012-01-01

312

PAH removal from spiked municipal wastewater sewage sludge using biological, chemical and electrochemical treatments.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) have been widely studied due to their presence in all the environmental media and toxicity to life. These molecules are strongly adsorbed on the particulate matters of soils, sludges or sediments because of their strong hydrophobicity which makes them less bioavailability, thus limiting their bioremediation. Different sludge treatment processes were tested to evaluate their performances for PAH removal from sludge prealably doped with 11 PAHs (5.5mg each PAH kg(-1) of dry matter (DM)): two biological processes (mesophilic aerobic digestion (MAD) and simultaneous sewage sludge digestion and metal leaching (METIX-BS)) were tested to evaluate PAH biodegradation in sewage sludge. In parallel, two chemical processes (quite similar Fenton processes: chemical metal leaching (METIX-AC) and chemical stabilization (STABIOX)) and one electrochemical process (electrochemical stabilization (ELECSTAB)) were tested to measure PAH removal by these oxidative processes. Moreover, PAH solubilisation from sludge by addition of a nonionic surfactant Tween 80 (Tw80) was also tested. The best yields of PAH removal were obtained by MAD and METIX-BS with more than 95% 3-ring PAH removal after a 21-day treatment period. Tw80 addition during MAD treatment increased 4-ring PAHs removal rate. In addition, more than 45% of 3-ring PAHs were removed from sludge by METIX-AC and during ELECSTAB process were quiet good with approximately 62% of 3-ring PAHs removal. However, little weaker removal of 3-ring PAHs (<35%) by STABIOX. None of the tested processes were efficient for the elimination of high molecular weight (> or = 5-ring) PAHs from sludge. PMID:17337031

Zheng, Xue-Jing; Blais, Jean-François; Mercier, Guy; Bergeron, Mario; Drogui, Patrick

2007-06-01

313

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

PubMed Central

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.

Gao, Yanzheng; Long, Jian; Wang, Qian

2013-01-01

314

Ca2+ promoted the low transformation efficiency of plasmid DNA exposed to PAH contaminants.  

PubMed

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 Ca(2+) 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 Ca(2+) enhanced the low transformation efficiency of DNA exposed to PAHs. Based on the co-sorption of Ca(2+) 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 Ca(2+) 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. PMID:23484001

Kang, Fuxing; Wang, Hong; Gao, Yanzheng; Long, Jian; Wang, Qian

2013-01-01

315

Estimation Haplotype Frequency of BglII\\/EcoRI\\/VNTR Markers at the PAH Gene Region in Iranian Population  

Microsoft Academic Search

Deficiency in phenylalanine hydroxylase (PAH) is the main molecular characteristic of phenylketonuria (PKU). So far over 500 different mutations in the PAH gene have been identified as associated with the disease. Mutation analysis of the PAH gene is a time-consuming and cost-effective procedure. Therefore, molecular markers which are highly linked to the PAH gene, have been used in carrier detection

Zahra Fazeli; Sadeq Vallian

2009-01-01

316

Impacts of UV radiation and photomodification on the toxicity of PAHs to the higher plant Lemna gibba (duckweed)  

Microsoft Academic Search

The toxicity of polycyclic aromatic hydrocarbons (PAHs) can be enhanced by both biotic and abiotic processes. This is exemplified by light, which, by virtue of the extensive [pi]-orbital systems of PAHs, can be a major factor in PAH toxicity. Light activation of PAHs is known to occur via photosensitization reactions and potentially by photomodification of the chemicals to more toxic

Xiao-Dong Huang; D. George Dixon; Bruce M. Greenberg

1993-01-01

317

Effect of Exposure Time, Contamination Level, and Type of PAH Compound on Biodegradation Capacity of Mangrove Sediment  

Microsoft Academic Search

Mangrove sediment had high natural attenuation potential with more than 50% of total PAHs being removed within 15 days. The efficiency in degrading PAHs varied with the declining order of phenanthrene (Phe), fluoranthene (Fla), and pyrene (Pyr). The Most Probable Number (MPN) of PAH-degrading bacteria in the PAH-contaminated slurries was 2 to 4 orders of magnitude higher than that in

Chu Ling Guo; Lin Ke; Zhi Dang; Nora Fungyee Tam

2012-01-01

318

Seasonal variation of polycyclic aromatic hydrocarbons (PAHs) emissions in China.  

PubMed

A regression model based on the provincial energy consumption data was developed to calculate the monthly proportions of residential energy consumption compared to the total year volume. This model was also validated by comparing with some survey and statistical data. With this model, a PAHs emission inventory with seasonal variation was developed. The seasonal variations of different sources in different regions of China and the spatial distribution of the major sources in different seasons were also achieved. The PAHs emissions were larger in the winter than in the summer, with a difference of about 1.3-folds between the months with the largest and the smallest emissions. Residential solid fuel combustion dominated the pattern of seasonal variation with the winter-time emissions as much as 1.6 times as that in the summer, while the emissions from wild fires and open fire straw burning was mainly concentrated during the spring and summer. PMID:18649978

Zhang, Yanxu; Tao, Shu

2008-12-01

319

Diagnostic formulation  

PubMed Central

Writing a ‘Diagnostic Formulation’ is a skill expected of candidates in the post-graduate examinations in psychiatry in most universities in India. However there is ambiguity regarding what the term means and how it should be written. This article is an attempt to provide some guidelines on this topic.

Kuruvilla, K.; Kuruvilla, Anju

2010-01-01

320

Uptake of (/sup 3/H)PAH and (/sup 14/C)urate into isolated proximal tubular segments of the pig kidney  

SciTech Connect

Segments of proximal convoluted (PCT) and proximal straight (PST) tubules of minipigs and normal-sized pigs were microdissected (without collagenase treatment) and incubated (30 min, 37/sup 0/C, pH 7.4) in Ringer solution (under O/sub 2/) containing (/sup 3/H)PAH (3.10/sup -5/ M) or (/sup 14/C)urate (9.10/sup -5/ M) and, in inhibitor studies, probenecid, pyrazinoic acid (PZA), urate, or PAH, all at 1 mM. In both strains the uptake of (/sup 3/H)PAH expressed as mean T/M ratio (cpm per ml tissue water/cpm per ml incubation medium) was significantly higher (P<0.001) in PCT than in PST. T/M was 34.7 +/- 5.6 (SE) in 34 PCT and 2.4 +/- 0.3 in 24 PST of eight minipigs. In two normal-sized pigs the T/M was 14.1 +/- 3.6 in 15 PCT and 1.5 +/- 0.1 in six PST. Similar results were obtained for (/sup 14/C)urate. In eight minipigs the T/M was 4.9 +/- 0.5 in 24 PCT and 2 +/- 0.2 in 25 PST. In normal-sized pigs the T/M was 3.8 +/- 0.3 in 35 PCT (five pigs) and 1.9 +/- 0.4 in eight PST (two pigs). In inhibitor studies urate significantly depressed the uptake of (/sup 3/H)PAH, and unlabeled PAH depressed the uptake of (/sup 14/C)urate. PZA significantly inhibited the uptake of (/sup 14/C)urate but not that of (/sup 3/H)PAH, whereas probenecid had a strong inhibitory efect on the uptake of both compounds. These results suggest that (/sup 14/C)urate and (/sup 3/H)PAH are transported by a transport system located mainly in the proximal convoluted tubule. These findings are in contrast in the findings are in contrast to the findings obtained in rabbits in which the transport system of PAH and urate is mainly located in the proximal part of the pars recta.

Schali, C.; Roch-Ramel, F.

1991-12-01

321

Two novel PAH gene mutations detected in Italian phenylketonuric patients  

Microsoft Academic Search

We report the identification by denaturing gradient gel electrophoresis and sequence analysis of two new phenylalanine hydroxylase\\u000a (PAH) gene mutations (IVS4nt-2 and N207S) in single chromosomes of two unrelated Italian phenylketonuric (PKU) patients. Interestingly,\\u000a mutation Y204C, found on the second mutant allele of family F1, has been previously detected in Chinese patients. Haplotype\\u000a analysis showed that the latter mutation is

Alessandra Argiolas; Paolo Bosco; Francesco Calì; Nadia Ceratto; Guido Anello; Enrica Riva; Giacomo Biasucci; Carla Carducci; Valentino Romano

1997-01-01

322

Survey of PAH Emission, 10-19.5 um  

NASA Astrophysics Data System (ADS)

A survey of the emission bands in the region 10-19.5 um, in planetary nebulae, proto-planetary objects, YSOs/HII regions, and related sources. The study will focus on the emission band at 16.4 um, attributed to PAHs, and will include the plateau of emission that extends from 15 um to the long wavelength limit of the Short-High IRS module.

Cruikshank, Dale; Sellgren, Kris

2004-09-01

323

PAH Emission From ULIRGs: Evidence For Unusual Grain Properties?  

Microsoft Academic Search

The tremendous power emerging from ultraluminous infrared galaxies (ULIRGs) is driven both by high levels of star-formation activity and AGN-related accretion. Observations of star-forming regions in the Milky Way and external star-forming galaxies provide evidence that the first of these energy generation mechanisms often also gives rise to emission from PAH molecules in the form of characteristic mid-IR features. Given

Jason A. Marshall; L. Armus; H. W. W. Spoon

2007-01-01

324

PAHs biodegradation in intertidal surface sediment by indigenous microorganisms.  

PubMed

In this study, the 30-day aerobic microorganism-mediated biodegradation of polycyclic aromatic hydrocarbons (PAHs) was investigated in four size fractions (i.e., <0.002, 0.002-0.031, 0.031-0.063 and >0.063 mm) of sand-dominated sediment S1 and mud-dominated S2 collected from intertidal zones in Bohai Bay (China). Prior to biodegradation, the total quantity of phenanthrene, fluoranthene and pyrene comprised more than 80 % of the total quantity of 16 EPA-priority PAHs in each size fraction, with the exception of 70.33 % found in the >0.063 mm fraction of sediment S1. Among the three dominant compounds, the intermediate size fraction (0.031-0.063 mm) showed higher levels of biodegradation than other size fractions in sediment S1 and S2. After pooling data from sediment S1 and S2 for joint analysis, it was observed that the biodegraded portion of the three dominant compounds showed negative correlations with both total organic carbon (TOC) and humic coverage index (HCI) in the size fractions. The observed negative correlation with TOC was in agreement with findings in many other studies, but the negative correlation with HCI had not been observed in early studies, which only investigated aged sediment/soil samples. The findings in this study indicated that the greatest bioavailability of PAHs in intertidal surface sediment may be present in sediment particles of intermediate size and mobility, and that intertidal sediment particles are less likely to experience sufficient ageing given periodical tidal disturbance. These findings have important implications for the assessment of the environmental fate of PAHs in intertidal regions. PMID:24504772

Jiao, Lixin; Chen, Hao; Meng, Wei; Lei, Kun; Zheng, Binghui

2014-05-01

325

898. Liver-Directed, AAV and Lentivirus-Mediated Gene Therapy in the Phenylketonuria Mouse Model Pah-enu2  

Microsoft Academic Search

A somatic gene therapy method for phenylketonuria (PKU) in a PKU-mouse model that carries the Pah-enu2 allele was developed. The Pah-enu2 allele is a mutant Pah gene, coding for a phenylalanine hydroxylase (PAH), with a single amino acid exchange in exon 7 giving rise to an inactive enzyme and hyperphenylalaninemia. The Pah-enu2 mouse, generously supplied by Dr. MacDonald (Wichita State

Zhaobing Ding; Panco Georgiev; Beat Thony

2005-01-01

326

Environmental assessment of PAHs in soils around the Anhui Coal District, China.  

PubMed

Thirty-three soil samples were collected from the Luling, Liuer, and Zhangji coal mines, in the Huaibei and Huainan areas, Anhui Province, China, in 2007. The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs), identified as priority pollutants by the US Environmental Protection Agency (EPA), were determined by gas chromatography-mass spectrometry (GC-MS). The sum of 16 US EPA PAHs ranged from 0.13 to 3.54 microg/g (dry weight basis) with a mean concentration of 0.84 microg/g. Among the three sampling sites selected around the coal mines, the site at the Luling coal mine revealed maximum concentration of PAHs, whereas minimum concentration was observed at the site at the Zhangji coal mine. In general, low-molecular-weight PAHs were predominant. The gob pile and coal preparation plant are the sources of PAHs pollution in surface soils in the vicinity of coal mines. The crops in rice paddies might adsorb some PAHs and reduce the PAHs content in soils from paddy fields. The vertical distribution of PAHs in two soil profiles indicates that PAHs contamination in soil profiles tends to occur high in the surface soils and markedly decreases with soil depth. For all depths, PAHs showed a similar distribution pattern, which is an indicator of a similar origin. The total B[a]P equivalent concentration (B[a]Peq) was found to be maximum at the Luling area, whereas it was minimum at Liuer zones. PMID:20091163

Wang, Ruwei; Liu, Guijian; Chou, Chen-Lin; Liu, Jingjing; Zhang, Jiamei

2010-07-01

327

Structural characterisation of humic acid-bound PAH residues in soil by 13 C -CPMAS-NMR-spectroscopy: evidence of covalent bonds  

Microsoft Academic Search

The fate of 13C-labelled phenanthrene and fluoranthene in different soil systems during biodegradation was studied. The soil humic acid fraction was isolated followed by structural characterisation using 13C-cross polarisation magic angle spinning nuclear magnetic resonance spectroscopy (13C-CPMAS-NMR). It could be demonstrated that especially the ratio between the concentrations of polycyclic aromatic hydrocarbons (PAHs) and soil humus matrix limits the usefulness

Thomas Käcker; Erhard T. K. Haupt; Christian Garms; Wittko Francke; Hans Steinhart

2002-01-01

328

Formation of nitro-PAHs from the heterogeneous reaction of ambient particle-bound PAHs with NO3/N2O5  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbons (PAHs) and their nitrated derivatives (nitro-PAHs) have been shown to be mutagenic in bacterial and mammalian assays and are classified as probable human carcinogens. Semi-volatile PAHs partition between the gas and particulate phases, depending on their liquid-phase vapor pressures and ambient temperatures. These PAHs have been extensively measured in ambient particulate matter and can ultimately undergo long-range transport from source regions (e.g., China to the western USA) (1). During transport these particle-bound PAHs may undergo reaction with NO3/N2O5 to form nitro-PAH derivatives. Previous studies of heterogeneous nitration of PAHs have used particles composed of graphite, diesel soot, and wood smoke (2-4). This study investigates the heterogeneous formation of nitro-PAHs from ambient particle-bound PAHs from Beijing, China and sites located within the Los Angeles air basin. These ambient particle samples, along with filters coated with isotopically labeled PAHs, were exposed to a mix of NO2/NO3/N2O5 in a 7000 L Teflon chamber, with analysis focused on the heterogeneous formation of molecular weight 247 and 273 nitro-PAHs. The heterogeneous formation of certain nitro-PAHs (including1-nitropyrene and 1- and 2-nitrotriphenylene) was observed for some, but not all, ambient samples. Formation of nitro-PAHs typically formed through gas-phase reactions (2-nitrofluoranthene and 2-nitropyrene) was not observed. The effect of particle age and local photochemical conditions during sampling on the degree of nitration in environmental chamber reactions, as well as ambient implications, will be presented. 1. Primbs, T.; Simonich, S.; Schmedding, D.; Wilson, G.; Jaffe, D.; Takami, A.; Kato, S.; Hatakeyama, S.; Kajii, Y. Environ. Sci. Technol. 2007, 41, 3551-3558. 2. Esteve, W.; Budzinski, H.; Villenave, E. Atmospheric Environment 2004, 38, 6063-6072. 3. Nguyen, M.; Bedjanian, Y.; Guilloteau, A. Journal of Atmospheric Chemistry 2009, 62, 139-150. 4. Kamens, R. M.; Zhi-Hua, F.; Yao, Y.; Chen, D.; Chen, S.; Vartiainen, M. Chemosphere 1994, 28, 1623-1632.

Zimmermann, K.; Jariyasopit, N.; Simonich, S. L.; Atkinson, R.; Arey, J.

2012-12-01

329

International Prostatic Symptom Score -- Voiding/Storage Subscore Ratio in Association with Total Prostatic Volume and Maximum Flow Rate Is Diagnostic of Bladder Outlet-Related Lower Urinary Tract Dysfunction in Men with Lower Urinary Tract Symptoms  

PubMed Central

Objectives The aim of this study was to investigate the predictive values of the total International Prostate Symptom Score (IPSS-T) and voiding to storage subscore ratio (IPSS-V/S) in association with total prostate volume (TPV) and maximum urinary flow rate (Qmax) in the diagnosis of bladder outlet-related lower urinary tract dysfunction (LUTD) in men with lower urinary tract symptoms (LUTS). Methods A total of 298 men with LUTS were enrolled. Video-urodynamic studies were used to determine the causes of LUTS. Differences in IPSS-T, IPSS-V/S ratio, TPV and Qmax between patients with bladder outlet-related LUTD and bladder-related LUTD were analyzed. The positive and negative predictive values (PPV and NPV) for bladder outlet-related LUTD were calculated using these parameters. Results Of the 298 men, bladder outlet-related LUTD was diagnosed in 167 (56%). We found that IPSS-V/S ratio was significantly higher among those patients with bladder outlet-related LUTD than patients with bladder-related LUTD (2.28±2.25 vs. 0.90±0.88, p<0.001). TPV was similar between the two groups; however, in contrast to patients with bladder-related LUTD, patients with bladder outlet-related LUTD had higher detrusor voiding pressure, lower Qmax values, and greater postvoid residual volumes. The combination of TPV30 ml and Qmax10 ml/sec had a PPV of 68.8% and a NPV of 53.5% for bladder outlet-related LUTD. When IPSS-T12 or IPSS-T15 was considered as an additional criterion, PPV increased to 75.0% and 78.5%, respectively, and the NPV decreased to 50.9% and 50.2%, respectively. When IPSS-V/S>1 or >2 was factored into the equation instead of IPSS-T, PPV were 91.4% and 97.3%, respectively, and NPV were 54.8% and 49.8%, respectively. Conclusions Combination of IPSS-T with TPV and Qmax increases the PPV of bladder outlet-related LUTD. Furthermore, including IPSS-V/S>1 or >2 into the equation results in a higher PPV than IPSS-T. IPSS-V/S>1 is a stronger predictor of bladder outlet-related LUTD than IPSS-T.

Liao, Chun-Hou; Kuo, Hann-Chorng

2013-01-01

330

The role of PAHs in the physics of the interstellar medium  

NASA Astrophysics Data System (ADS)

In the interstellar medium (ISM), PAHs are abundant and also carry most of the dust surface. They are thus privileged sites for surface reactions such as the formation of H2. In regions penetrated by UV photons, PAHs loose electrons by the photoelectric effect and efficiently heat the gas. In more shielded regions, PAH recombine and may carry an important fraction of the cloud electronic charge which plays an important role in the gas dynamics and chemistry. We review here processes involving PAHs which control key aspects of the physics of the ISM. We also discuss the corresponding observational constraints. Most of these processes involve a detailed knowledge of the charge of PAHs and we therefore review current models in this area. We argue that more laboratory measurements of the rate of electronic capture on large PAH cations are needed.

Verstraete, L.

2011-03-01

331

Stabilization of sewage sludge by different biochars towards reducing freely dissolved polycyclic aromatic hydrocarbons (PAHs) content.  

PubMed

The objective of the study was to identify the effect of various biochars on the content of freely dissolved (Cfree) PAHs in sewage sludge. Apart from the evaluation of biochars obtained from various materials, the study also included the determination of the effects of biochar particle sizes and biochar production temperature on their ability to bind PAHs in sewage sludge. Increase in biochar dose caused a gradual reduction of Cfree PAHs content, but only up to the biochar dose of 5%. Depending on the kind of initial material from which the biochar was produced, the reduction of Cfree PAHs content in sewage sludge varied from 17.4% to 58.0%. Both the temperature and the particle size of biochar had an effect on PAH free concentration reduction. Biochars characterised by a low polarity index (O/C or (O+N)/C) reduced the level of Cfree PAHs better than biochars with a higher polarity index value. PMID:24495539

Oleszczuk, Patryk; Zieli?ska, Anna; Cornelissen, Gerard

2014-03-01

332

Extraction agents for the removal of polycyclic aromatic hydrocarbons (PAHs) from soil in soil washing technologies.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) in soil have been recognised as a serious health and environmental issue due to their carcinogenic, mutagenic and teratogenic properties. One of the commonly employed soil remediation techniques to clean up such contamination is soil washing or solvent extraction. The main factor which governs the efficiency of this process is the solubility of PAHs in the extraction agent. Past field-scale soil washing treatments for PAH-contaminated soil have mainly employed organic solvents or water which is either toxic and costly or inefficient in removing higher molecular weight PAHs. Thus, the present article aims to provide a review and discussion of the alternative extraction agents that have been studied, including surfactants, biosurfactants, microemulsions, natural surfactants, cyclodextrins, vegetable oil and solution with solid phase particles. These extraction agents have been found to remove PAHs from soil at percentages ranging from 47 to 100% for various PAHs. PMID:24100092

Lau, Ee Von; Gan, Suyin; Ng, Hoon Kiat; Poh, Phaik Eong

2014-01-01

333

Distribution, sources and ecological risk assessment of PAHs in surface sediments from Guan River Estuary, China.  

PubMed

The contamination of surface sediments in Guan River Estuary, China, by polycyclic aromatic hydrocarbons (PAHs) has been fully investigated. Total concentrations of 21 PAHs ranged from 90 to 218 ng/g with an average of 132.7 ng/g, which is relatively low in comparison with other estuaries around the world. PAH concentrations appeared to be positively correlated with clay content and negatively correlated with sediment grain size. Source identification implied that the PAHs originated mainly from pyrolytic sources. However, source patterns may be continuously changed to a petrogenic origin due to the heavy ship traffic and continuous discharge of oily sewage in this area. The PAH levels were also compared with international Sediments Quality Guidelines and Sediments Quality Criteria, and the results indicated low negative effects for most individual PAHs. However, toxic effects related to FLO would occur occasionally in most locations in the estuary. PMID:24508044

He, Xinran; Pang, Yong; Song, Xiaojuan; Chen, Binlin; Feng, Zhihua; Ma, Yuqin

2014-03-15

334

Sorption of Polycyclic Aromatic Hydrocarbons (PAHs) to Lignin: Effects of Hydrophobicity and Temperature.  

PubMed

The study of the sorption of contaminants to lignin is significant for understanding the migration of contaminants in the environment as well as developing low cost sorbent. In this study, sorption of three polycyclic aromatic hydrocarbons (PAHs), naphthalene, acenaphthene and phenanthrene, to lignin was investigated. Sorption isotherms were well described by both linear and Freundlich sorption models. Sorption coefficients of PAHs to lignin from water obtained from regression of both linear model (K d) and Freundlich model (K f) were highly positively correlated with hydrophobicity of PAHs. The amorphous structure of lignin provided sufficient sorption domain for partitioning of PAHs, and the attraction between PAHs molecules and aromatic fractions in lignin via ?-? electron-donor-acceptor (?-? EDA) interaction is hypothesized to provide a strong sorption force. Thermodynamic modeling revealed that sorption of PAHs to lignin was a spontaneous and exothermic process. PMID:24838935

Zhang, Ming; Ahmad, Mahtab; Lee, Sang Soo; Xu, Li Heng; Ok, Yong Sik

2014-07-01

335

Spatial distribution of PAHs in a contaminated valley in Southeast China  

Microsoft Academic Search

A survey was conducted on the accumulation and spatial distribution of PAHs in surface soils under different land use patterns in a valley in the Yangtze Delta region with an area of 10 km2 containing 15 small copper- and zinc-smelting furnaces. Sixty-five topsoil (0–20 cm) samples were collected and 16 PAHs were determined. The average amount of all the 16 PAHs ranged

Weiqin Xing; Yongming Luo; Longhua Wu; Jing Song; Wei Qian; Peter Christie

2006-01-01

336

Identification and Characterization of an Antigen I\\/II Homologous Gene, pah , from Streptococcus downei  

Microsoft Academic Search

Antigen I\\/II of Streptococcus mutans is a cell surface protein involved in the adherence of cells to tooth surfaces. In this study, an antigen I\\/II homologous\\u000a gene, pah, was identified and sequenced from Streptococcus downei MFe28 using degenerate polymerase chain reaction (PCR) and the gene-walking method. The pah gene encodes a cell-wall-anchoring protein, PAh, containing 1565 amino acids. At the

Haruki Tamura; Arisa Yamada; Hirohisa Kato

2008-01-01

337

Successful Treatment of Low PAH-Contaminated Sewage Sludge in Aerobic Bioreactors (7 pp)  

Microsoft Academic Search

Background, Aims and Scope   Polycyclic Aromatic Hydrocarbons (PAHs) are known for their adverse and cumulative effects at low concentration. In particular,\\u000a the PAHs accumulate in sewage sludge during wastewater treatment, and may thereafter contaminate agricultural soils by spreading\\u000a sludge on land. Therefore, sludge treatment processes constitute the unique opportunity of PAH removal before their release\\u000a in the environment. In this

Eric Trably; Dominique Patureau

2006-01-01

338

The NASA Ames PAH IR Spectroscopic Database: A Demo of its Contents and Web Tools  

NASA Astrophysics Data System (ADS)

The features formerly known as the Unidentified Infrared (UIR) Emission Bands are now generally attributed to polycyclic aromatic hydrocarbons (PAHs). Exploitation of these features as astrophysical and astrochemical probes requires the IR properties of PAHs under interstellar conditions. To fulfill this need, we experimentally measured and theoretically computed the 2-2000 µm spectra of many PAHs over the past 18 years at NASA's Ames Research Center. Today's collection comprises about 600 theoretically computed and 60 laboratory measured spectra of PAHs in different forms. The molecules in the collection range in size from C10H8 to C130H28. For most of these, spectra are available for PAHs in their neutral and singly charged (+/-) states. In some cases, IR spectra of multiply charged species were also computed. The database includes pure PAHs; PAHs containing nitrogen (PANHs), oxygen, and silicon; PAHs with side groups; PAHs with extra hydrogens; and PAHs complexed with iron and magnesium. This collection of PAH spectra from 2 - 2000 µm has been assembled into a uniform database, which we will make publicly available on the web in early 2009. A WebGUI interface has been developed that can effectively interrogate the database using a variety of queries, such as formula, molecular name, charge, specific number of atoms, etc. Several molecules can be selected in such a process and one can obtain their 3-D structures, plot and co-add their spectra, adjust parameters such as the bandwidth, download their data and print graphs. The database can also be downloaded as a whole and IDL-routines are provided to interrogate it. This talk will present an overview of the contents and the web-GUI tools of the NASA Ames PAH IR Spectroscopic Database. Hands-on demonstrations will be available at the SOFIA Booth.

Boersma, Christiaan; Sánchez de Armas, F.; Ricca, A.; Cami, J.; Peeters, E.; Mattioda, A. L.; Bauschlicher, C. W., Jr.; Allamandola, L. J.

2009-01-01

339

Study of Human Exposure to Particulate PAHs Using Personal Air Samplers  

Microsoft Academic Search

Three common sources of environmental exposure to particulate polycyclic aromatic hydrocarbons (PAHs) in Taiwan were chosen\\u000a for this study. They are smoke of incense burning, exhausts of motor vehicles, and fumes of charcoal burning. The campus environment\\u000a without any specific PAH sources (nonpoint sources) was chosen as the control. The particulate PAH concentrations in the air\\u000a samples containing smoke of

C. Y. Kuo; Y. W. Hsu; H. S. Lee

2003-01-01

340

Distribution and transport of PAHs in soil profiles of different water irrigation areas in Beijing, China.  

PubMed

Vertical distribution characteristics and transport mechanisms of polycyclic aromatic hydrocarbons (PAHs) in soil profiles (0-5.5 m) of different water irrigation areas in the southeast suburb of Beijing were analyzed and compared. 16 priority PAHs on the United States Environmental Protection Agency (US EPA) list were analyzed using gas chromatography and mass spectrometry (GC-MS). The relationship between the properties of soil and PAHs was also studied by statistical analyses. The results showed that total PAH concentrations in the topsoils of the wastewater irrigation (WWI) area, reclaimed water irrigation (RWI) area, groundwater irrigation (GWI) area were much higher than those in the deep soils, with the concentrations of 726.0, 206.8 and 42.8 ?g kg(-1) (dry wt), respectively. The low molecular weight (LMW) PAHs (2-3 ring) including naphthalene (Nap), phenanthrene (Phe), fluorene (Fl) dominated the layers (0.5-5.5 m) underneath the surfaces. The migration of LMW PAHs was faster than that of high molecular weight (HMW) PAHs and LMW PAHs were transported in dissolved matter. The different soil textures of three sites caused the differences in the variation ranges of PAHs in the profiles. The statistical analyses showed a significant linear positive correlation between PAHs and total organic carbon (TOC). The 2-4 ring PAHs were detected in the wastewater and reclaimed waters, which was consistent with those in the soil profiles. The presence of PAHs in the soil profiles was mainly due to the irrigation of wastewater. Wastewater reuse guidelines and standards for irrigation should be established urgently. PMID:24781137

Jin, Aifang; He, Jiangtao; Chen, Sunuan; Huang, Guoxin

2014-05-28

341

Yeast Pah1p phosphatidate phosphatase is regulated by proteasome-mediated degradation.  

PubMed

Yeast PAH1-encoded phosphatidate phosphatase is the enzyme responsible for the production of the diacylglycerol used for the synthesis of triacylglycerol that accumulates in the stationary phase of growth. Paradoxically, the growth phase-mediated inductions of PAH1 and phosphatidate phosphatase activity do not correlate with the amount of Pah1p; enzyme abundance declined in a growth phase-dependent manner. Pah1p from exponential phase cells was a relatively stable protein, and its abundance was not affected by incubation with an extract from stationary phase cells. Recombinant Pah1p was degraded upon incubation with the 100,000 × g pellet fraction of stationary phase cells, although the enzyme was stable when incubated with the same fraction of exponential phase cells. MG132, an inhibitor of proteasome function, prevented degradation of the recombinant enzyme. Endogenously expressed and plasmid-mediated overexpressed levels of Pah1p were more abundant in the stationary phase of cells treated with MG132. Pah1p was stabilized in mutants with impaired proteasome (rpn4?, blm10?, ump1?, and pre1 pre2) and ubiquitination (hrd1?, ubc4?, ubc7?, ubc8?, and doa4?) functions. The pre1 pre2 mutations that eliminate nearly all chymotrypsin-like activity of the 20 S proteasome had the greatest stabilizing effect on enzyme levels. Taken together, these results supported the conclusion that Pah1p is subject to proteasome-mediated degradation in the stationary phase. That Pah1p abundance was stabilized in pah1? mutant cells expressing catalytically inactive forms of Pah1p and dgk1? mutant cells with induced expression of DGK1-encoded diacylglycerol kinase indicated that alteration in phosphatidate and/or diacylglycerol levels might be the signal that triggers Pah1p degradation. PMID:24563465

Pascual, Florencia; Hsieh, Lu-Sheng; Soto-Cardalda, Aníbal; Carman, George M

2014-04-01

342

Influence of smoking parameters on the concentration of polycyclic aromatic hydrocarbons (PAHs) in Danish smoked fish.  

PubMed

A new method for the analysis of 25 polycyclic aromatic hydrocarbon (PAH) compounds in fish was developed, validated, and used for the quantification of PAHs in 180 industrially smoked fish products. The method included pressurized liquid extraction, gel-permeation chromatography (Bio-beads S-X3), solid-phase extraction (silica gel), and gas chromatography-mass spectrometry analysis. The sum concentration of 25 PAHs ([summation operator]PAH(25)) was highest in smoked herring (n = 3) and mackerel fillets (n = 13), with an average concentration of 320 and 235 microg kg(-1), respectively. Lowest average [summation operator]PAH(25) concentrations were obtained for indirectly smoked trout (26 microg kg(-1)). Principal component analysis was used to correlate processing parameters to PAH concentrations and to identify the effects of these parameters. The analysis showed that for salmon hot-smoking conditions lead to higher SigmaPAH(25) than cold smoking, and for other fish species direct smoking leads to higher SigmaPAH(25) than indirect smoking. Also, the usage of common alder increases the PAH contamination compared with beech. The effects of smoking time, combustion temperatures, and two types of smoke-generating material on the [summation operator]PAH(25) were also tested in a pilot plant study with smoked trout as a model fish. In addition to confirming that increased combustion temperatures and usage of common alder in comparison with beech increased [summation operator]PAH(25), it was also revealed that the PAH concentration decreased in the order fish skin > outer layer of the fish muscle > inner part of the fish muscle. PMID:20640961

Duedahl-Olesen, L; Christensen, J H; Højgård, A; Granby, K; Timm-Heinrich, M

2010-09-01

343

Vertical distribution and environmental significance of PAHs in soil profiles in Beijing, China  

Microsoft Academic Search

Vertical distribution of both the concentration and composition of polycyclic aromatic hydrocarbons (PAHs) in ten profiles\\u000a in Beijing has been investigated. The results showed that PAH concentrations and compositions in topsoil from different sampling\\u000a sites were different. PAH concentrations were much higher in topsoil of the investigated urban area, industrial region, and\\u000a paddy field with wastewater irrigation than in other

Qing Wei Bu; Zhi Huan Zhang; Song Lu; Feng Peng He

2009-01-01

344

Occurrence and Distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in Bolgoda and Beira Lakes, Sri Lanka  

Microsoft Academic Search

The pollution of polycyclic aromatic hydrocarbons (PAHs) has been widely used to assess the potential impact of anthropogenic\\u000a activities on aquatic environments because their occurrence in water is closely tied to urban activities. Many PAHs possess\\u000a mutagenic and carcinogenic properties (Menzie et al. 1992). PAH distribution and toxic potentials have therefore been the focus of numerous studies in waterways including

K. A. S. Pathiratne; O. C. P. De Silva; David Hehemann; Ian Atkinson; Robert Wei

2007-01-01

345

Screening Level of PAHs in Sediment Core from Lake Hongfeng, Southwest China  

Microsoft Academic Search

Using data from a 25-year retrospective of polycyclic aromatic hydrocarbons (PAHs) in sediment core from Lake Hongfeng, Southwest\\u000a China, their possible sources and potential toxicologic significance were investigated. The total PAH concentrations (16 priority\\u000a PAHs as proposed by the United States Environmental Protection Agency) in sediments ranged from 2936.1 to 5282.3 ng\\/g and\\u000a gradually increased from the analyzed deeper sediments to

Jian-Yang Guo; Feng-Chang Wu; Liang Zhang; Hai-Qing Liao; Run-Yu Zhang; Wei Li; Xiao-Li Zhao; She-Jun Chen; Bi-Xian Mai

2011-01-01

346

Polycyclic Aromatic Hydrocarbons (PAHs) in Sediments of the White Sea, Russia  

Microsoft Academic Search

The extent of environmental contamination and sources of polycyclic aromatic hydrocarbon (PAH) compounds to sediments of the White Sea are evaluated and compared with previously published results for adjacent Arctic Sea areas. Concentrations of two- to six-ring PAHs of molecular mass 128–278 including perylene and sediment characteristics are considered in this investigation. Mean ?PAH concentration was 61±34 ng\\/g dw (n=11)

Vladimir M Savinov; Tatiana N Savinova; JoLynn Carroll; Gennady G Matishov; Salve Dahle; Kristoffer Næs

2000-01-01

347

NSTX Diagnostics and Operation: Status and Plans  

SciTech Connect

The low aspect ratio and low magnetic field of the National Spherical Torus Experiment (NSTX) create many challenges for plasma diagnostics and control, as well as opportunities for studying new plasma phenomena. This paper describes the diagnostics now installed for studies of confinement, stability and edge plasma phenomena, and some of the diagnostic developments planned for the near future. The design of the plasma control system and plans for its development are also presented.

M.G. Bell; R.E. Bell; B.P. LeBlanc; S.S. Medley; and the NSTX Research Team

2001-08-30

348

Enhanced NIF neutron activation diagnostics  

NASA Astrophysics Data System (ADS)

The NIF neutron activation diagnostic suite relies on removable activation samples, leading to operational inefficiencies and a fundamental lower limit on the half-life of the activated product that can be observed. A neutron diagnostic system measuring activation of permanently installed samples could remove these limitations and significantly enhance overall neutron diagnostic capabilities. The physics and engineering aspects of two proposed systems are considered: one measuring the 89Zr/89mZr isomer ratio in the existing Zr activation medium and the other using potassium zirconate as the activation medium. Both proposed systems could improve the signal-to-noise ratio of the current system by at least a factor of 5 and would allow independent measurement of fusion core velocity and fuel areal density.

Yeamans, C. B.; Bleuel, D. L.; Bernstein, L. A.

2012-10-01

349

Enhanced NIF neutron activation diagnostics  

SciTech Connect

The NIF neutron activation diagnostic suite relies on removable activation samples, leading to operational inefficiencies and a fundamental lower limit on the half-life of the activated product that can be observed. A neutron diagnostic system measuring activation of permanently installed samples could remove these limitations and significantly enhance overall neutron diagnostic capabilities. The physics and engineering aspects of two proposed systems are considered: one measuring the {sup 89}Zr/{sup 89m}Zr isomer ratio in the existing Zr activation medium and the other using potassium zirconate as the activation medium. Both proposed systems could improve the signal-to-noise ratio of the current system by at least a factor of 5 and would allow independent measurement of fusion core velocity and fuel areal density.

Yeamans, C. B.; Bleuel, D. L.; Bernstein, L. A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2012-10-15

350

Special Diagnostics  

NASA Technical Reports Server (NTRS)

This section contains a number of special diagnostics that are designed to examine certain mechanisms. Section 1 reports on the method used to test the photochemical partitioning in the models. Sections 2 and 3 represent efforts to examine the model calculated production and removal rates for ozone and how the values are combined with transport rates in the models to produce the simulated ozone distributions. Sections 4 and 5 concentrate on polar processes including the dynamics aspect of vortex confinement and the chemical aspects of chlorine activation.

Ko, Malcolm K. W.; Salawitch, Ross J.; Jackman, Charles H.; Considine, David B.; Douglass, Anne R.

1999-01-01

351

PM2.5-bound PAHs and hydroxy-PAHs in atmospheric aerosol samples: Correlations with season and with physical and chemical factors  

NASA Astrophysics Data System (ADS)

Over a one-year period, the concentrations of ten polycyclic aromatic hydrocarbons (PAHs) and two of their hydroxy derivatives (OH-PAHs) were monitored in a suburb of Madrid (Spain). The levels of other chemical indicators of urban pollution (nitrogen oxides, sulphur oxides, etc.), as well as a series of meteorological variables (temperature, atmospheric pressure, etc.) were determined simultaneously. PAH concentrations varied according to the environmental conditions such that depending on the wind direction and speed, levels exceeded those expected for outside the central city area. Concentrations of 2-hydroxyphenanthrene ranged from 12 to 200 pg m-3 and those of 1-hydroxypyrene from 3 to 60 pg m-3. Their variations were directly related to levels of phenanthrene and pyrene and also found to depend on the weather conditions, especially temperature and atmospheric pressure. Through multivariate analysis (factor and cluster analyses) a clear link was detected between the concentrations of PAHs or hydroxy-PAHs and those of other chemical pollutants (nitrogen and sulphur oxides). We also observed an inverse relationship with temperature, ozone concentration, solar radiation and UV radiation intensity. Changes in both PAHs and OH-PAHs were clearly seasonal, increasing in the colder months and undergoing a reduction in the warmer months of the year.

Barrado, Ana Isabel; García, Susana; Barrado, Enrique; Pérez, Rosa María

2012-03-01

352

Sources, fate, and effects of PAHs in shallow water environments: a review with special reference to small watercraft  

USGS Publications Warehouse

Polycyclic aromatic hydrocarbons (PAHs) are aromatic hydrocarbons with two to seven fused carbon (benzene) rings that can have substituted groups attached. Shallow coastal, estuarine, lake, and river environments receive PAHs from treated wastewater, stormwater runoff, petroleum spills and natural seeps, recreational and commercial boats, natural fires, volcanoes, and atmospheric deposition of combustion products. Abiotic degradation of PAHs is caused by photooxidation, photolysis in water, and chemical oxidation. Many aquatic microbes, plants, and animals can metabolize and excrete ingested PAHs; accumulation is associated with poor metabolic capabilities, high lipid content, and activity patterns or distributions that coincide with high concentrations of PAHs. Resistance to biological transformation increases with increasing number of carbon rings. Four- to seven-ring PAHs are the most difficult to metabolize and the most likely to accumulate in sediments. Disturbance by boating activity of sediments, shorelines, and the surface microlayer of water causes water column re-entry of recently deposited or concentrated PAHs. Residence time for PAHs in undisturbed sediment exceeds several decades. Toxicity of PAHs causes lethal and sublethal effects in plants and animals, whereas some substituted PAHs and metabolites of some PAHs cause mutations, developmental malformations, tumors, and cancer. Environmental concentrations of PAHs in water are usually several orders of magnitude below levels that are acutely toxic, but concentrations can be much higher in sediment. The best evidence for a link between environmental PAHs and induction of cancerous neoplasms is for demersal fish in areas with high concentrations of PAHs in the sediment.

Albers, P.H.

2002-01-01

353

Concentrations and possible sources of PAHs in sediments from Bohai Bay and adjacent shelf  

Microsoft Academic Search

Concentrations, spatial distribution and sources of 16 polycyclic aromatic hydrocarbons (PAHs) listed by the United States\\u000a Environmental Protection Agency as priority pollutants were investigated in surface sediments of Bohai Bay, North China. Total\\u000a concentrations of PAHs were in the range of 140.6–300.7 ng\\/g (dry wt), with an average of 188.0 ng\\/g. The three predominant\\u000a PAHs were phenanthrene, acenaphthene and naphthalene. Sedimentary PAH

Ningjing Hu; Xuefa Shi; Jihua Liu; Peng Huang; Yanguang Liu; Ying Liu

2010-01-01

354

Historical changes in the concentrations of polycyclic aromatic hydrocarbons (PAHs) in Lake Peipsi sediments.  

PubMed

The distribution of 11 individual polycyclic aromatic hydrocarbons (PAHs) was analysed in a (210)Pb dated sediment core from the deepest area of Lake Peipsi and in four surface sediment samples taken from littoral areas. According to the concentrations in the core three groups of PAHs may be distinguished: (1) relatively stable concentrations of PAHs within the whole studied time interval; (2) very low concentrations in sediments accumulated before intensive anthropogenic impact (from 19th century up to the 1920s) following a slight increase and (3) an overall increase in PAH concentrations since the 1920s up to the present. Comprehensive analysis of PAHs in the core and monitoring data obtained in the 1980s together with the lithology of sediments show that an increase of anthropogenically induced PAHs correlates well with the history of fuel consumption in Estonia and speaks about atmospheric long-distance transport of PAHs. The continuous increase of PAH concentrations since the 1920s do not support the earlier hypothesis about the dominating impact of the oil shale fired power plants near the lake, because their emissions decreased significantly in the 1990s. The concentration of PAHs in the deep lake core sample correlates well with the content of organic matter, indicating absorption and co-precipitation with plankton in the sediment. PMID:18270801

Punning, Jaan-Mati; Terasmaa, Jaanus; Vaasma, Tiit; Kapanen, Galina

2008-09-01

355

Recent Advances in Laboratory Infrared Spectroscopy of Polycyclic Aromatic Hydrocarbons: PAHs in the Far Infrared  

NASA Technical Reports Server (NTRS)

Over 25 years of observations and laboratory work have shown that the mid-IR spectra of a majority of astronomical sources are dominated by emission features near 3.3, 6.2, 7.7, and 11.2 microns, which originate in free polycyclic aromatic hydrocarbon (PAH) molecules. PAHs dominate the mid-IR emission from many galactic and extragalactic objects. As such, this material tracks a wide variety of astronomical processes, making this spectrum a powerful probe of the cosmos Apart from bands in the mid-IR, PAHs have bands spanning the Far-IR (FIR) and emission from these FIR features should be present in astronomical sources showing the Mid-IR PAH bands. However, with one exception, the FIR spectral characteristics are known only for a few neutral small PAHs trapped in salt pellets or oils at room temperature, data which is not relevant to astrophysics. Furthermore, since most emitting PAHs responsible for the mid-IR astronomical features are ionized, the absence of any experimental or theoretical PAH ion FIR spectra will make it impossible to correctly interpret the FIR data from these objects. In view of the upcoming Herschel space telescope mission and SOFIA's FIR airborne instrumentation, which will pioneer the FIR region, it is now urgent to obtain PAH FIR spectra. This talk will present an overview recent advances in the laboratory spectroscopy of PAHs, Highlighting the FIR spectroscopy along with some quantum calculations.

Mattioda, Andrew L.; Ricca, Alessandra; Tucker, Jonathan; Boersma, Christiaan; Bauschlicher, Charles, Jr.; Allamandola, Louis J.

2010-01-01

356

The Investigation of Reducing PAHs Emission from Coal Pyrolysis by Gaseous Catalytic Cracking  

PubMed Central

The catalytic cracking method of PAHs for the pyrolysis gaseous products is proposed to control their pollution to the environment. In this study, the Py-GC-MS is used to investigate in situ the catalytic effect of CaO and Fe2O3 on the 16 PAHs from Pingshuo coal pyrolysis under different catalytic temperatures and catalyst particle sizes. The results demonstrate that Fe2O3 is effective than that of CaO for catalytic cracking of 16 PAHs and that their catalytic temperature corresponding to the maximum PAHs cracking rates is different. The PAHs cracking rate is up to 60.59% for Fe2O3 at 600°C and is 52.88% at 700°C for CaO. The catalytic temperature and particle size of the catalysts have a significant effect on PAHs cracking rate and CaO will lose the capability of decreasing 16 PAHs when the temperature is higher than 900°C. The possible cracking process of 16 PAHs is deduced by elaborately analyzing the cracking effect of the two catalysts on 16 different species of PAHs.

Wang, Yulong; Zhao, Ruifang; Zhang, Chun; Li, Guanlong; Zhang, Jing; Li, Fan

2014-01-01

357

Interrelationship of Pyrogenic Polycyclic Aromatic Hydrocarbon (PAH) Contamination in Different Environmental Media  

PubMed Central

Interrelationships between pyrogenic polycyclic aromatic hydrocarbons (PAHs) were assessed in air, soil, water, sediment, and tree leaves by using multi-media monitoring data. Concurrent concentration measurements were taken bimonthly for a year for the multi-media at urban and suburban sites. PAH level correlations between air and other media were observed at the urban site but were less clear at the suburban site. Considering a closer PAHs distribution/fate characteristics to soil than suspended solids, contamination in sediment seemed to be governed primarily by that in soil. The partitioning of PAHs in waters could be better accounted for by sorption onto black carbon and dissolved organic carbon.

Kim, Seung-Kyu; Lee, Dong Soo; Shim, Won Joon; Yim, Un Hyuk; Shin, Yong-Seung

2009-01-01

358

Characterization of PAHs in the atmosphere of carbon black manufacturing workplaces.  

PubMed

The objective of this study was set out to characterize the polycyclic aromatic hydrocarbon (PAH) content in the atmosphere of an oil furnace carbon black manufacturing plant located in southern Taiwan. A standard semi-volatile sampling train, the PS-1 sampler, was used to collect samples from eight areas, including the feedstock oil unloading, furnace, filtering/micro-pulverization, pelletizing, packaging, office/outside, office/inside, and boundary area, respectively. For each area, side-by-side static samples were collected simultaneously and a total of 16 samples were obtained. For each collected sample, the adsorbent-retained PAH content and the filter-retained PAH content were used directly to determine the concentrations of gaseous-phase PAHs and particle-bound PAHs, respectively. The gas chromatograph/mass spectrometer (GC/MS) technique was used for PAH analyses, and a total of 21 PAH species were determined. Results show the gaseous-phase PAHs accounted for only 69.2% of the total PAH content for samples collected from the packaging area, which was significantly lower than those samples collected from the rest of seven areas (ranging from 96.3 to 99.7%). The result is not so surprising since the packaging area had the highest dust concentration due to the releasing of carbon black dusts during the packaging process. In this study, we further examine the contribution of gaseous-phase PAHs to the total benzo[a]pyrene equivalent (BaP(eq)) content from the health-risk assessment view of point. It can be found the contribution of gaseous-phase PAHs to the total BaP(eq) content (63.1%) was quite comparable to the corresponding contribution to the total PAH content for samples collected from the packaging area. However, a different trend can be found for samples collected from the other seven areas, where the contributions of gaseous-phase PAHs to the total BaP(eq) content (ranging from 67.7 to 93.4%) were lower than the corresponding contributions to the total PAH content. The above results can be explained by PAH homologues that contained in both gaseous-phase and particle-bound PAHs. It was found the gaseous-phase PAHs contained higher fractions of less carcinogenic low molecular weight PAH homologues, whereas particle-bound PAHs contained higher fractions of more carcinogenic high molecular weight PAH homologues. Considering the contributions of gaseous-phase PAHs to both total PAH content and total BaP(eq) content were well above 50% for the eight studied areas, it is concluded that both particle-bound and gaseous-phase PAHs should be included for assessing the exposures of carbon black workers. PMID:11900904

Tsai, Perng Jy; Shieh, Hong Yong; Lee, Wen Jhy; Lai, Soon Onn

2002-04-26

359

Detoxication of Structurally Diverse Polycyclic Aromatic Hydrocarbon (PAH) o-Quinones by Human Recombinant Catechol-O-methyltransferase (COMT) via O-Methylation of PAH Catechols*  

PubMed Central

Polycyclic aromatic hydrocarbons (PAH) are environmental and tobacco carcinogens. Metabolic activation of intermediate PAH trans-dihydrodiols by aldo-keto reductases (AKRs) leads to the formation of electrophilic and redox-active o-quinones. We investigated whether O-methylation by human recombinant soluble catechol-O-methyltransferase (S-COMT) is a feasible detoxication step for a panel of structurally diverse PAH-catechols produced during the redox-cycling process. Classes of PAH non-K-region o-quinones (bay region, methylated bay region, and fjord region o-quinones) produced by AKRs were employed in the studies. PAH o-quinones were reduced to the corresponding catechols by dithiothreitol under anaerobic conditions and then further O-methylated by human S-COMT in the presence of S-[3H]adenosyl-l-methionine as a methyl group donor. The formation of the O-methylated catechols was detected by HPLC-UV coupled with in-line radiometric detection, and unlabeled products were also characterized by LC-MS/MS. Human S-COMT was able to catalyze O-methylation of all of the PAH-catechols and generated two isomeric metabolites in different proportions. LC-MS/MS showed that each isomer was a mono-O-methylated metabolite. 1H NMR was used to assign the predominant positional isomer of benzo[a]pyrene-7,8-catechol as the O-8-monomethylated catechol. The catalytic efficiency (kcat/Km) varied among different classes of PAH-catechols by 500-fold. The ability of S-COMT to produce two isomeric products from PAH-catechols was rationalized using the crystal structure of the enzyme. We provide evidence that O-8-monomethylated benzo[a]pyrene-7,8-catechol is formed in three different human lung cell lines. It is concluded that human S-COMT may play a critical role in the detoxication of PAH o-quinones generated by AKRs.

Zhang, Li; Jin, Yi; Chen, Mo; Huang, Meng; Harvey, Ronald G.; Blair, Ian A.; Penning, Trevor M.

2011-01-01

360

Polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides in water columns from the Pearl River and the Macao harbor in the Pearl River Delta in South China.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) were measured in suspended particles and dissolved phase from the Baiertang water column and the Macao water column samples as collected from the Guangzhou channel of the Pearl River and the Macao harbor, where the sediments were heavily contaminated with organic pollutants. Total OCPs concentration varies from 23.4 to 61.7 ng/l in Baiertang water column and from 25.2 to 67.8 ng/l in Macao column, while total PAHs concentration varies from 987.1 to 2878.5 ng/l in the Baiertang water column and from 944.0 to 6654.6 ng/l in the Macao column. The vertical distribution profiles of pollutants and the partition of pollutants between particles and dissolved phases indicate that the sediments in Baiertang act as an important source of selected pollutants, and the pollutants in water of this region were mainly originated from the release and re-suspension of contaminants residing in the sediments. The sediments in Macao harbor act as a reservoir for organochlorine pesticides, such as DDTs mainly introduced by river inflow from Xijiang and PAHs input by brackish water from the Lingdingyang estuary. Combustion of fossil fuels and petroleum input are the main sources of PAHs in the Macao water column, while combustion of fossil fuels and coal is responsible for the PAHs in the Baiertang water column. The ratios of DDT/(DDD+DDE) for the Macao water column samples demonstrate that such chemicals were input into this region in recent times. PMID:15172816

Luo, Xiaojun; Mai, Bixian; Yang, Qingshu; Fu, Jiamo; Sheng, Guoying; Wang, Zhishi

2004-06-01

361

Impact of Inoculation Protocols, Salinity, and pH on the Degradation of Polycyclic Aromatic Hydrocarbons (PAHs) and Survival of PAH-Degrading Bacteria Introduced into Soil  

PubMed Central

Degradation of polycyclic aromatic hydrocarbons (PAHs) and survival of bacteria in soil was investigated by applying different inoculation protocols. The soil was inoculated with Sphingomonas paucimobilis BA 2 and strain BP 9, which are able to degrade anthracene and pyrene, respectively. CFU of soil bacteria and of the introduced bacteria were monitored in native and sterilized soil at different pHs. Introduction with mineral medium inhibited PAH degradation by the autochthonous microflora and by the strains tested. After introduction with water (without increase of the pore water salinity), no inhibition of the autochthonous microflora was observed and both strains exhibited PAH degradation.

Kastner, Matthias; Breuer-Jammali, Maren; Mahro, Bernd

1998-01-01

362

Platinum ratio search versus golden ratio search  

Microsoft Academic Search

In this simulation study, we examine the traditional golden ratio search in view of cost minimization and search risk, and propose an alternative search plan with what we call “platinum ratio”. The golden ratio search has been thought the best for unimodal optimization. However, our study shows that the golden ratio search is the best only in the sense of

Xia Pan

2008-01-01

363

The levels of PAHs and aryl hydrocarbon receptor effects in sediments of Taihu Lake, China.  

PubMed

A total of 16 priority polycyclic aromatic hydrocarbons (PAHs) in sediment samples from Taihu Lake were analyzed by instruments, and sediment extracts were assayed for aryl hydrocarbon receptor (AhR)-mediated ethoxyresorufin-o-deethylase (EROD) induction using a rat hepatoma cell line (H4IIE). The cause-effect relationship between the observed EROD activity and chemical concentrations of PAHs was examined. Our results showed that sediment extracts could induce significant AhR effects, and the bioassay-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents of raw extracts (TEQ(bio)s) ranged from 2.7 to 39.8 pg g(-1) dw. Chemical analysis showed that 16 PAHs were all detected in all samples, and their total concentrations (?16PAHs) ranged from 179.8 to 1,669.4 ng g(-1) dw. The abundance of sedimentary PAHs in the three regions (Meiliang Bay, Gonghu Bay, and Xukou Bay) showed a decreasing trend from the inflow region to the outflow region. Chemical analysis-derived TEQs (TEQ(cal)s) contributed by PAHs ranged from 1.6 to 20.7 pg g(-1) dw. The mean contribution rates (CRs) of PAHs to TEQ(bio)s were 48.9%. In Meiliang Bay, EROD effects of 60% samples were caused by PAHs whose CRs were more than 60%, while in most sampling sites of Gonghu Bay and Xukou Bay, the CRs of PAHs to TEQ(bio)s were basically below 40%. In addition, preliminary ecological risk assessment found that PAHs in sediments have very low ecological impact based on the chemical data of PAHs, while the sediments might pose an unacceptable risk to aquatic organisms and their predators based on the data of TEQ(bio). These findings showed that EROD effects of sediment extracts from Taihu Lake were also caused by other compounds, such as dioxins, polychlorinated biphenyls, etc., together. PMID:24497304

Lei, Bingli; Kang, Jia; Wang, Xuetong; Yu, Yingxin; Zhang, Xiaolan; Wen, Yu; Wang, Yipei

2014-05-01

364

Association of Plasma IL-6 and Hsp70 with HRV at Different Levels of PAHs Metabolites  

PubMed Central

Background Exposure to polycyclic aromatic hydrocarbons (PAHs) is associated with reduced heart rate variability (HRV), a strong predictor of cardiovascular diseases, but the mechanism is not well understood. Objectives We hypothesized that PAHs might induce systemic inflammation and stress response, contributing to altered cardiac autonomic function. Methods HRV indices were measured using a 3-channel digital Holter monitor in 800 coke oven workers. Plasma levels of interleukin-6 (IL-6) and heat shock protein 70 (Hsp70) were determined using ELISA. Twelve urinary PAHs metabolites (OH-PAHs) were measured by gas chromatography-mass spectrometry. Results We found that significant dose-dependent relationships between four urinary OH-PAHs and IL-6 (all Ptrend<0.05); and an increase in quartiles of IL-6 was significantly associated with a decrease in total power (TP) and low frequency (LF) (Ptrend?=?0.014 and 0.006, respectively). In particular, elevated IL-6 was associated in a dose-dependent manner with decreased TP and LF in the high-PAHs metabolites groups (all Ptrend<0.05), but not in the low-PAHs metabolites groups. No significant association between Hsp70 and HRV in total population was found after multivariate adjustment. However, increased Hsp70 was significantly associated with elevated standard deviation of NN intervals (SDNN), TP and LF in the low-PAHs metabolites groups (all Ptrend<0.05). We also observed that both IL-6 and Hsp70 significantly interacted with multiple PAHs metabolites in relation to HRV. Conclusions In coke oven workers, increased IL-6 was associated with a dose-response decreased HRV in the high-PAHs metabolites groups, whereas increase of Hsp70 can result in significant dose-related increase in HRV in the low-PAHs metabolites groups.

He, Xiaosheng; Feng, Yingying; Yang, Liangle; Zhu, Xiaoyan; Deng, Qifei; Wu, Tangchun; Zhang, Xiaomin

2014-01-01

365

Laboratory Measurements of the Recombination of PAH Ions with Electrons: Implications for Interstellar Chemistry  

NASA Astrophysics Data System (ADS)

Polycyclic Aromatic Hydrocarbons (PAHs) are thought to be the most abundant molecules in the interstellar medium after H2 and CO. The chemistry responsible for the formation or the destruction of PAH molecules in the gas phase is however not well understood. The experimental study of the reactivity and the spectroscopy of isolated neutral and ionized PAHs remains a challenge. No specific spectral identification of interstellar PAHs has to date occurred. It has been suggested that the species investigated in the laboratory may be too small to survive photodissociation in the interstellar medium. Another hypothesis is that photoproduced PAH cations may react rapidly with species that are abundant in the interstellar medium, such as electrons. Electron-ion recombination constitutes a major neutralisation channel which may also lead to dissociation. Usually, the recombination rates used in the astrochemical models either are calculated on the basis that the PAH can be modeled as a small conductive disk or are derived from experimental values for similar species, by means of a size dependent sticking coefficient. As experimental data are severely lacking, it is difficult to assess the exact contribution of the PAH+ recombination channel. A unique experiment has been developed to measure the recombination rate coefficient of photoproduced PAH cations with electrons in a flowing afterglow. The method has been employed to measure the recombination rate coefficient of a set of ionized PAHs: azulene (C10H8), acenaphthene (C12H10), anthracene (C14H10), and pyrene (C16H10). The measured values are consistent with recombination rate coefficients of similar PAH cations already studied, and in particular, with the values measured for phenanthrene