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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

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

3

Diagnostics for specific PAHs in the far-IR: searching neutral naphthalene and anthracene in the Red Rectangle  

NASA Astrophysics Data System (ADS)

Context: .In the framework of the interstellar polycyclic aromatic hydrocarbons (PAHs) hypothesis, far-IR skeletal bands are expected to be the fingerprints of single species in this class. Aims: .We address the question of detectability of low energy PAH vibrational bands, with respect to spectral contrast and intensity ratio with "classical" Aromatic Infrared Bands (AIBs). Methods: .We extend our established Monte Carlo model of the photophysics of specific PAHs in astronomical environments to include rotational and anharmonic band structure. The required molecular parameters were calculated in the framework of the Density Functional Theory. Results: .We calculate the detailed spectral profiles of three low-energy vibrational bands of neutral naphthalene and four low-energy vibrational bands of neutral anthracene. They are used to establish detectability constraints based on intensity ratios with "classical" AIBs. A general procedure is suggested to select promising diagnostics and tested on available Infrared Space Observatory data for the Red Rectangle nebula. Conclusions: .The search for single, specific PAHs in the far-IR is a challenging, but promising task, especially in view of the forthcoming launch of the Herschel Space Observatory.

Mulas, G.; Malloci, G.; Joblin, C.; Toublanc, D.

2006-09-01

4

Source Identification of Polycyclic Aromatic Hydrocarbons by Diagnostic Ratios and Positive Matrix Factorization  

NASA Astrophysics Data System (ADS)

Although polycyclic aromatic hydrocarbons (PAHs) are also of natural origin, in many regions their environmental concentrations have strongly increased due to human activities. These semivolatile organic compounds are generally formed during incomplete combustion. Other sources include volatilization from unburned petroleum or tire abrasion in road traffic. Among all pollutants PAHs pose the highest human health hazard in Europe (WHO, 2003). A multivariate statistical method, positive matrix factorization (PMF; Paatero, 1997), and diagnostic ratios of individual PAHs (e.g. Yunker et al., 2002) are used for PAH source identification in central Europe. To minimise confounding factors such as differences in volatility, water solubility, adsorption etc., diagnostic ratios should be restricted to PAHs of similar molecular mass (Readman et al., 1987). Furthermore, different reactivities are limiting. Nevertheless, the application of PAH diagnostic ratios is often inconclusive, because substance patterns (profiles) have not been reported for all sources and ranges for various sources overlap. The complete profiles are made use of by statistical methods such as factor analysis, UNMIX and PMF (Tauler et al., 2006). However, these methods can be unreliable, because of incomplete knowledge of source profiles and the analysis' sensitivity to the data distribution. A unique 12-year data set of concentrations of PAHs (16 individual substances, 2 phases, weekly) in air, measured at the regional observatory Košetice, Czech Republic, is examined, together with shorter time series from Leipzig (urban background) and Schwartenberg (subalpine mountain background), Germany. Also, retene and coronene as specific source markers measured in Košetice from 2006 on are included into the analysis. An extensive literature search on PAH emission profiles was conducted. This data set was accomplished by measurements at sites in the Zlínsko region, Czech Republic, which are strongly dominated by a single, well defined PAH source. By determination of the total PAH concentrations (sum of gas and particulate phases) the propagation of sampling artefacts related to PAH partitioning into statistical errors is avoided. The main results are: Major PAH source categories exhibit a significant seasonality, coronene as a marker for traffic (Bi et al., 2003) should be used with care. Long-term trends of the major PAH sources are insignificant. Literature: Bi X.H., Sheng G.Y., Peng P., Chen Y.J., Zhang Z.Q., Fu J.M., 2003. Distribution of particulate- and vapor-phase n-alkanes and polycyclic aromatic hydrocarbons in urban atmosphere of Guangzhou, China. Atmos. Environ. 37, 289-298. Paatero P. (1997): Least square formulation of robust non-negative factor analysis, Chemometrics Intelligent Lab. Systems 37, 23-35. Readman J.W., Mantoura R.F., Rhead M.M., 1987. A record of polycyclic aromatic hydrocarbon (PAH) pollution obtained from accreting sediments of the Tamar estuary, UK: evidence for non-equilibrium behaviour of PAH. Sci. Total Environ. 66, 73-94. Tauler R., Paatero P., Hopke P., Henry R.C., Spiegelman C., Park E.S., Poirot R.L., 2006. State of the art in methods and software for the identification, resolution and apportionment of contamination sources In: Summit on Environmental Modelling and Software (Proceedings of the iEMSs 3rd Biennial Meeting; Voinov A., Jakeman A.J., Rizzoli A.E., eds.), International Environmental Modelling and Software Society, Burlington, USA. WHO (2003) - World Health Organization: Health risks of persistent organic pollutants from long-range transboundary air pollution. WHO Regional Office for Europe, Copenhagen, 252 pp. Yunker M.B., Macdonald R.W., Vingarzan R., Mitchell R.H., Goyette D., Sylvestre S., 2002. PAHs in the Fraser River basin: a critical appraisal of PAH ratios as indicators of PAH source and composition. Org. Geochem. 33, 489-515.

Dvorska, A.; Jarkovsky, J.; Lammel, G.; Klanova, J.

2009-04-01

5

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. PMID:24948841

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

2014-01-01

6

PAHs in the bulk atmospheric deposition of the Seine river basin: source identification and apportionment by ratios, multivariate statistical techniques and scanning electron microscopy.  

PubMed

The origin of polycyclic aromatic hydrocarbons (PAH) contamination in bulk atmospheric deposition at two sites of the Seine estuary, one urban and one industrial, has been investigated. The PAH profiles indicate that PAHs mainly have a pyrolytic origin, both in urban and industrial areas. PAH sources vary during the year with an increase of high molecular weight PAH proportions (especially for carcinogenic PAHs) in winter, that means an increase of combustion processes such as domestic heating. Ratios of indicator PAHs (FTH/FTH+PYR and IcdP/IcdP+BghiP) confirm the pyrolytic origin of PAHs. In summer, ratios show the presence of industrial sources. In addition to these two methods, a factor analysis/multiple linear regression model was applied and gave an approximation of PAH source apportionment. PAH were found to be associated predominantly with emissions from road traffic (gasoline and diesel), that accounts for 17-34%. Domestic heating is a very important PAH source in urban areas and accounts for up to 85% of PAHs in winter. Industrial emissions (refineries...) account for 25% in the industrial area in summer. Each is an identified source category for the region and these results are consistent with fly-ashes identified by scanning electron microscopy. This study demonstrates that a combination of source identification methods is a far more efficient than one method alone. PMID:17109933

Motelay-Massei, Anne; Ollivon, Donatienne; Garban, Brigitte; Tiphagne-Larcher, Karen; Zimmerlin, Irène; Chevreuil, Marc

2007-02-01

7

Construct validity of a diagnostic ratio measure of gender stereotypes  

Microsoft Academic Search

We examined the construct validity of C. L. Martin's [(1987), “A Ratio Measure of Sex Stereotyping,” Journal of Personality and Social Psychology, Vol. 52, pp. 489–499] diagnostic ratio method for measuring consensual gender stereotypes and individual differences in gender stereotyping. This method is based on estimates that respondents make for percentages of men and women that possess gender stereotypic personality

Albert A. Cota; Anne Reid; Kenneth L. Dion

1991-01-01

8

Using atmospheric measurements of PAH and quinone compounds at roadside and urban background sites to assess sources and reactivity  

NASA Astrophysics Data System (ADS)

The sources of polycyclic aromatic hydrocarbon (PAH) in various environmental media have commonly been identified based on the ratios of concentrations of selected PAH congeners. These ratios are applicable to various environmental media and distinguish between sources originating from vehicular emissions, petroleum products, petroleum combustion, coal and biomass burning. In this study an evaluation of PAH diagnostic ratios is provided for vapour and particulate phase samples collected simultaneously at well defined roadside and suburban sites in Birmingham, UK. It focuses on 14 PAH and 11 quinone compounds which were measured at both sites to obtain information upon traffic emissions (and subsequently a PAH congener traffic profile) and to evaluate the validity of PAH diagnostic ratios. The results suggest that PAH ratios of the low molecular weight compounds are less stable and more susceptible to atmospheric processing, indicating the importance of determining PAH ratio threshold values based on well defined samples. Quinone to parent-PAH ratios were also examined to assess the potential reactivity of PAH compounds, where the results suggest that significant atmospheric processing occurs during transport, altering the ratios between both sites, in a manner related to the relative reactivity of different PAH congeners.

Alam, Mohammed S.; Delgado-Saborit, Juana Maria; Stark, Christopher; Harrison, Roy M.

2013-10-01

9

Correlations in polycyclic aromatic hydrocarbon (PAH) concentrations in UK ambient air and implications for source apportionment.  

PubMed

The extent of correlation in polycyclic aromatic hydrocarbon (PAH) concentration data obtained by the UK PAH Monitoring and Analysis Air Quality Network from March 2008 to November 2010 has been assessed. Application of principal component analysis (PCA) to the dataset has revealed that the concentrations of the vast majority of PAHs are very highly correlated. The use of diagnostic PAH ratios (including a new benzo[b]naph[2,1-d]thiophene/benzo[a]pyrene diagnostic ratio), and a novel 'combined diagnostic ratio - PCA' approach has revealed information about the main sources of PAH at individual Network sites, allowing the sites to be grouped in terms of those influenced by solid fuel use, industry and traffic, and those of an urban or rural nature. Solid fuel use has also been delineated from other fuel burning. Conclusions are drawn about a number of UK PAH Network sites - four sites are shown to be influenced significantly by solid fuel use, and the sites in South Wales and at London Marylebone Road are found to be located in distinct and unusual PAH pollution climates - the identification of a unique PAH pollution climate in South Wales is a key and novel conclusion of the work. PMID:22699714

Brown, Andrew S; Brown, Richard J C

2012-08-01

10

Application of Binary Diagnostic Ratios of Polycyclic Aromatic Hydrocarbons for Identification of Tsunami 2004 Backwash Sediments in Khao Lak, Thailand  

PubMed Central

Identification of Tsunami deposits has long been a controversial issue among geologists. Although there are many identification criteria based on the sedimentary characteristics of unequivocal Tsunami deposits, the concept still remains ambiguous. Apart from relying on some conventional geological, sedimentological, and geoscientific records, geologists need some alternative “proxies” to identify the existence of Tsunami backwash in core sediments. Polycyclic aromatic hydrocarbons (PAHs) are a class of very stable organic molecules, which can usually be presented as complex mixtures of several hundred congeners; one can assume that the “Tsunami backwash deposits” possess different fingerprints of PAHs apart from those of “typical marine sediments.” In this study, three-dimensional plots of PAH binary ratios successfully identify the Tsunami backwash deposits in comparison with those of global marine sediments. The applications of binary ratios of PAHs coupled with HCA are the basis for developing site-specific Tsunami deposit identification criteria that can be applied in paleotsunami deposits investigations.

2014-01-01

11

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

12

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

13

Using deuterated PAH amendments to validate chemical extraction methods to predict PAH bioavailability in soils.  

PubMed

Validating chemical methods to predict bioavailable fractions of polycyclic aromatic hydrocarbons (PAHs) by comparison with accumulation bioassays is problematic. Concentrations accumulated in soil organisms not only depend on the bioavailable fraction but also on contaminant properties. A historically contaminated soil was freshly spiked with deuterated PAHs (dPAHs). dPAHs have a similar fate to their respective undeuterated analogues, so chemical methods that give good indications of bioavailability should extract the fresh more readily available dPAHs and historic more recalcitrant PAHs in similar proportions to those in which they are accumulated in the tissues of test organisms. Cyclodextrin and butanol extractions predicted the bioavailable fraction for earthworms (Eisenia fetida) and plants (Lolium multiflorum) better than the exhaustive extraction. The PAHs accumulated by earthworms had a larger dPAH:PAH ratio than that predicted by chemical methods. The isotope ratio method described here provides an effective way of evaluating other chemical methods to predict bioavailability. PMID:21236537

Gomez-Eyles, Jose L; Collins, Chris D; Hodson, Mark E

2011-04-01

14

The stability and utility of diagnostic ratio hydrocarbon fingerprinting for soils contaminated with petroleum hydrocarbons  

SciTech Connect

In order to recover costs for oil spill cleanup and restoration regulatory agencies and trustees of natural resources are interested in identifying parties responsible for hydrocarbon releases, and for associated environmental damages. Chemical analyses of contaminated soil and groundwater samples are currently used to identify the sources of contamination in soil and groundwater systems. However, conventional hydrocarbon fingerprinting approaches such as EPA Method 8015, EPA Method 8270, and ASTM Method 3328-91 afford a low resolution fingerprint that is easily degraded in the environment. The challenge to the hydrocarbon chemist is to develop an analytical approach that minimizes the impact of environmental weathering and biodegradation on the oil signature and improves the accuracy of oil source identification. An advanced chemical fingerprinting strategy is presented that combines sensitive and hydrocarbon specific analytical methods with a detailed interpretive strategy designed to minimize the impacts of environmental weathering and biodegradation. Data will be presented from a series of oil biodegradation studies in soil that clearly demonstrate the utility and stability of source ratio analysis over a wide range of oil degradation states and oil types. Using principal component analysis, stable source ratios of C[sub 3]-dibenzothiophenes/C[sub 3]-phenanthrenes, and C[sub 2]-dibenzothiophenes/C[sub 2]-phenanthrenes were identified and evaluated. These source ratios retain their characteristic source ratio signature even after 95 percent of the PAH and dibenzothiophene target analytes and 70 percent of the total oil has been biodegraded.

Douglas, G.S.; Sara McMillen

1996-01-01

15

The stability and utility of diagnostic ratio hydrocarbon fingerprinting for soils contaminated with petroleum hydrocarbons  

SciTech Connect

In order to recover costs for oil spill cleanup and restoration regulatory agencies and trustees of natural resources are interested in identifying parties responsible for hydrocarbon releases, and for associated environmental damages. Chemical analyses of contaminated soil and groundwater samples are currently used to identify the sources of contamination in soil and groundwater systems. However, conventional hydrocarbon fingerprinting approaches such as EPA Method 8015, EPA Method 8270, and ASTM Method 3328-91 afford a low resolution fingerprint that is easily degraded in the environment. The challenge to the hydrocarbon chemist is to develop an analytical approach that minimizes the impact of environmental weathering and biodegradation on the oil signature and improves the accuracy of oil source identification. An advanced chemical fingerprinting strategy is presented that combines sensitive and hydrocarbon specific analytical methods with a detailed interpretive strategy designed to minimize the impacts of environmental weathering and biodegradation. Data will be presented from a series of oil biodegradation studies in soil that clearly demonstrate the utility and stability of source ratio analysis over a wide range of oil degradation states and oil types. Using principal component analysis, stable source ratios of C{sub 3}-dibenzothiophenes/C{sub 3}-phenanthrenes, and C{sub 2}-dibenzothiophenes/C{sub 2}-phenanthrenes were identified and evaluated. These source ratios retain their characteristic source ratio signature even after 95 percent of the PAH and dibenzothiophene target analytes and 70 percent of the total oil has been biodegraded.

Douglas, G.S.; Sara McMillen

1996-12-31

16

Spatial distribution, potential risk assessment, and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in sediments of Lake Chaohu, China.  

PubMed

Twenty-nine sediment samples were collected from Lake Chaohu, a shallow eutrophic lake in Eastern China, and were analyzed for 15 priority polycyclic aromatic hydrocarbons (PAHs) to determine the spatial distribution and exposure risks of PAHs. Three receptor models, the principal component analysis-multiple linear regression (PCA-MLR) model, the positive matrix factorization (PMF) model, and the Unmix model, were used in combination with the PAHs diagnostic ratios to investigate the potential source apportionment of PAHs. A clear gradient in the spatial distribution and the potential toxicity of PAHs was observed from west to east in the sediments of Lake Chaohu. ?15PAH concentrations and the TEQ were in the range of 80.82-30 365.01 ng g(-1) d.w. and 40.77-614.03, respectively. The highest values of the aforementioned variables were attributed to urban-industrial pollution sources in the west lake region, and the levels decreased away from the river inlets. The three different models yielded excellent correlation coefficients between the predicted and measured levels of the 15 PAH compounds. Similarly, source apportionment results were derived from the three receptor models and the PAH diagnostic ratios, suggesting that the highest contribution to the PAHs was from coal combustion and wood combustion, followed by vehicular emissions. The PMF model yielded the following contributions to the PAHs from gasoline combustion, diesel combustion, unburned petroleum emissions, and wood combustion: 34.49, 24.61, 16.11, 13.01, and 11.78 %, respectively. The PMF model produced more detailed source apportionment results for the PAHs than the PCA-MLR and Unmix models. PMID:24920262

Li, Chaocan; Huo, Shouliang; Yu, Zhiqiang; Xi, Beidou; Zeng, Xiangying; Wu, Fengchang

2014-10-01

17

Stable carbon isotope ratio of polycyclic aromatic hydrocarbons (PAHs) in the environment: validation of isolation and stable carbon isotope analysis methods  

E-print Network

column chromatography, gel permeation chromatography and thin layer chromatography. The mean recovery of PAHs after the purification procedure was approximately 80 %. Sample purities after purification were verified by GC/FID and full scan mass...

Kim, Moon Koo

2004-11-15

18

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

19

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

20

DNA methylation ratio variability may impede clinical application of cancer diagnostic markers.  

PubMed

Hypermethylation at promoter regions of tumour suppressor genes is diagnostic for many cancers. Many genomic regions that may be the targets for clinical diagnostic assays have been identified through use of measuring systems reliant on bisulphite conversion, but few of these promising markers are in clinical use. The comparability of a widely used DNA methylation measuring system involving bisulphite conversion was evaluated by supplying three experienced centres with methylated DNA reference material mixtures that were independently prepared and characterised by mass spectrometry and high-pressure liquid chromatography. A replication scheme was designed to evaluate reproducibility of key analytical steps within and between laboratories by regression analysis. In general, methylation was underestimated and methylation ratio values were highly variable. The difference in methylation ratio between CpG sites was the key contributor to variable results. The CpG site effect followed a similar pattern at all centres and at all methylation levels examined indicating that sequence context had a major effect on methylation ratio measurement using the bisulphite conversion process. The magnitude of underestimation combined with the variability of measurements between CpG sites compromises the concept of measuring genomic regional methylation by averaging the methylation ratios of many CpG sites. There were no significant differences in replicate bisulphite conversions or sample work-up and instrument analysis at each centre thus making this technique suitable for comparative intralaboratory investigations. However, it may not be suitable for a routine diagnostic assay without extensive standardisation efforts. PMID:24948089

Burke, Daniel; Fu, Shuang; Forbes-Smith, Michael; Bhat, Somanath; Partis, Lina; Coldham, Thosaporn; Frenkel, Robert; Emslie, Kerry R

2014-10-01

21

Profile of PAHs in the inhalable particulate fraction: source apportionment and associated health risks in a tropical megacity.  

PubMed

The present study proposed to investigate the atmospheric distribution, sources, and inhalation health risks of polycyclic aromatic hydrocarbons (PAHs) in a tropical megacity (Delhi, India). To this end, 16 US EPA priority PAHs were measured in the inhalable fraction of atmospheric particles (PM(10); aerodynamic diameter, ? 10 ?m) collected weekly at three residential areas in Delhi from December 2008 to November 2009. Mean annual 24 h PM(10) levels at the sites (166.5-192.3 ?g m(-3)) were eight to ten times the WHO limit. Weekday/weekend effects on PM(10) and associated PAHs were investigated. ?(16)PAH concentrations (sum of 16 PAHs analyzed; overall annual mean, 105.3 ng m(-3); overall range, 10.5-511.9 ng m(-3)) observed were at least an order of magnitude greater than values reported from European and US cities. Spatial variations in PAHs were influenced by nearness to traffic and thermal power plants while seasonal variation trends showed highest concentrations in winter. Associations between ?(16)PAHs and various meteorological parameters were investigated. The overall PAH profile was dominated by combustion-derived large-ring species (85-87 %) that were essentially local in origin. Carcinogenic PAHs contributed 58-62 % to ?(16)PAH loads at the sites. Molecular diagnostic ratios were used for preliminary assessment of PAH sources. Principal component analysis coupled with multiple linear regression-identified vehicular emissions as the predominant source (62-83 %), followed by coal combustion (18-19 %), residential fuel use (19 %), and industrial emissions (16 %). Spatio-temporal variations and time-evolution of source contributions were studied. Inhalation cancer risk assessment showed that a maximum of 39,780 excess cancer cases might occur due to lifetime inhalation exposure to the analyzed PAH concentrations. PMID:22527461

Sarkar, Sayantan; Khillare, P S

2013-02-01

22

NON-EQUILIBRIUM IONIZATION EFFECTS ON THE DENSITY LINE RATIO DIAGNOSTICS OF O IV  

SciTech Connect

The dynamic timescales in the solar atmosphere are shorter than the ionization and recombination times of many ions used for line ratio diagnostics of the transition region and corona. The long ionization and recombination times for these ions imply that they can be found far from their equilibrium temperatures, and spectroscopic investigations require more care before being trusted in giving correct information on local quantities, such as density and temperature. By solving the full time-dependent rate equations for an oxygen model atom in the three-dimensional numerical model of the solar atmosphere generated by the Bifrost code, we are able to construct synthetic intensity maps and study the emergent emission. We investigate the method of electron density diagnostics through line ratio analysis of the O IV 140.1 nm to the 140.4 nm ratio, the assumptions made in carrying out the diagnostics, and the different interpretations of the electron density. The results show big discrepancies between emission in statistical equilibrium and emission where non-equilibrium (NEQ) ionization is treated. Deduced electron densities are up to an order of magnitude higher when NEQ effects are accounted for. The inferred electron density is found to be a weighted mean average electron density along the line of sight and has no relation to the temperature of emission. This study shows that numerical modeling is essential for electron density diagnostics and is a valuable tool when the ions used for such studies are expected to be out of ionization equilibrium. Though this study has been performed on the O IV ion, similar results are also expected for other transition region ions.

Olluri, K.; Gudiksen, B. V.; Hansteen, V. H., E-mail: kosovare.olluri@astro.uio.no [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway)

2013-04-10

23

Non-equilibrium Ionization Effects on the Density Line Ratio Diagnostics of O IV  

NASA Astrophysics Data System (ADS)

The dynamic timescales in the solar atmosphere are shorter than the ionization and recombination times of many ions used for line ratio diagnostics of the transition region and corona. The long ionization and recombination times for these ions imply that they can be found far from their equilibrium temperatures, and spectroscopic investigations require more care before being trusted in giving correct information on local quantities, such as density and temperature. By solving the full time-dependent rate equations for an oxygen model atom in the three-dimensional numerical model of the solar atmosphere generated by the Bifrost code, we are able to construct synthetic intensity maps and study the emergent emission. We investigate the method of electron density diagnostics through line ratio analysis of the O IV 140.1 nm to the 140.4 nm ratio, the assumptions made in carrying out the diagnostics, and the different interpretations of the electron density. The results show big discrepancies between emission in statistical equilibrium and emission where non-equilibrium (NEQ) ionization is treated. Deduced electron densities are up to an order of magnitude higher when NEQ effects are accounted for. The inferred electron density is found to be a weighted mean average electron density along the line of sight and has no relation to the temperature of emission. This study shows that numerical modeling is essential for electron density diagnostics and is a valuable tool when the ions used for such studies are expected to be out of ionization equilibrium. Though this study has been performed on the O IV ion, similar results are also expected for other transition region ions.

Olluri, K.; Gudiksen, B. V.; Hansteen, V. H.

2013-04-01

24

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

25

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

26

GAS EXCITATION IN ULIRGs: MAPS OF DIAGNOSTIC EMISSION-LINE RATIOS IN SPACE AND VELOCITY  

SciTech Connect

Emission-line spectra extracted at multiple locations across 39 ultraluminous infrared galaxies have been compiled into a spectrophotometric atlas. Line profiles of H{alpha}, [N II], [S II], [O I], H{beta}, and [O III] are resolved and fit jointly with common velocity components. Diagnostic ratios of these line fluxes are presented in a series of plots, showing how the Doppler shift, line width, gas excitation, and surface brightness change with velocity at fixed position and also with distance from the nucleus. One general characteristic of these spectra is the presence of shocked gas extending many kiloparsecs from the nucleus. In some systems, the rotation curves of the emitting gas indicate motions that suggest gas disks, which are most frequent at early merger stages. At these early merger stages, the emission line ratios indicate the presence of shocked gas, which may be triggered by the merger event. We also report the general characteristics of the integrated spectra.

Soto, Kurt T.; Martin, Crystal L. [Physics Department, University of California, Santa Barbara, CA 93106-9530 (United States)

2012-11-15

27

Distribution and Source Apportionment of Polycyclic Aromatic Hydrocarbons (PAHs) in Forest Soils from Urban to Rural Areas in the Pearl River Delta of Southern China  

PubMed Central

The upper layer of forest soils (0–20 cm depth) were collected from urban, suburban, and rural areas in the Pearl River Delta of Southern China to estimate the distribution and the possible sources of polycyclic aromatic hydrocarbons (PAHs). Total concentrations of PAHs in the forest soils decreased significantly along the urban–suburban–rural gradient, indicating the influence of anthropogenic emissions on the PAH distribution in forest soils. High and low molecular weight PAHs dominated in the urban and rural forest soils, respectively, implying the difference in emission sources between the areas. The values of PAH isomeric diagnostic ratios indicated that forest soil PAHs were mainly originated from traffic emissions, mixed sources and coal/wood combustion in the urban, suburban and rural areas, respectively. Principal component analysis revealed that traffic emissions, coal burning and residential biomass combustion were the three primary contributors to forest soil PAHs in the Pearl River Delta. Long range transportation of PAHs via atmosphere from urban area might also impact the PAHs distribution in the forest soils of rural area. PMID:24599040

Xiao, Yihua; Tong, Fuchun; Kuang, Yuanwen; Chen, Bufeng

2014-01-01

28

Gas Excitation in ULIRGS: Maps of Diagnostic Emission-Line Ratios in Space and Velocity  

E-print Network

Emission-line spectra extracted at multiple locations across 39 ultraluminous infrared galaxies have been compiled into a spectrophotometric atlas. Line profiles of H alpha, [N II], [S II], [O I], H beta, and [O III] are resolved and fit jointly with common velocity components. Diagnostic ratios of these line fluxes are presented in a series of plots, showing how the Doppler shift, line width, gas excitation, and surface brightness change with velocity at fixed position and also with distance from the nucleus. One general characteristic of these spectra is the presence of shocked gas extending many kiloparsecs from the nucleus. In some systems, the shocked gas appears as part of a galactic gas disk based on its rotation curve. These gas disks appear primarily during the early stages of the merger. The general characteristics of the integrated spectra are also presented.

Soto, Kurt T

2012-01-01

29

Seasonal changes, identification and source apportionment of PAH in PM1.0  

NASA Astrophysics Data System (ADS)

The objective of this research was to evaluate the seasonal variation of PAHs in PM1.0, as well as to identify and quantify the contributions of each source profile using the PMF receptor model. PM1.0 samples were collected on PTFE filters from August 2011 to July 2013 in the Metropolitan Area of Porto Alegre, Rio Grande do Sul, Brazil. The samples were extracted using the EPA method TO-13A and 16 Polycyclic Aromatic Hydrocarbons (PAHs) were analyzed using a gaseous chromatograph coupled with a mass spectrometer (GC-MS). Also, the data discussed in this study were analyzed to identify the relations of the PAHs concentrations with NOx, NO, O3 and meteorological parameters (temperature, solar radiation, wind speed, relative humidity). The results showed that in winter, concentrations of total PAHs were significantly higher than in summer, thus showing their seasonal variation. The identification of emission sources by applying diagnostic ratios confirmed that PAHs in the study area originate from mobile sources, especially, from diesel and gasoline emissions. The analysis by PMF receptor model showed the contribution of these two main sources of emissions, too, followed by coal combustion, incomplete combustion/unburned petroleum and wood combustion. The toxic equivalent factors were calculated to characterize the risk of cancer from PAH exposure to PM1.0 samples, and BaP and DahA dominated BaPeq levels.

Agudelo-Castañeda, Dayana Milena; Teixeira, Elba Calesso

2014-10-01

30

Isotopic 32S/33S ratio as a diagnostic of presolar grains from novae  

E-print Network

Measurements of sulphur isotopes in presolar grains can help to identify the astrophysical sites in which these grains were formed. A more precise thermonuclear rate of the 33S(p,gamma)34Cl reaction is required, however, to assess the diagnostic ability of sulphur isotopic ratios. We have studied the 33S(3He,d)34Cl proton-transfer reaction at 25 MeV using a high-resolution quadrupole-dipole-dipole-dipole magnetic spectrograph. Deuteron spectra were measured at ten scattering angles between 10 and 55 degrees. Twenty-four levels in 34Cl over Ex = 4.6 - 5.9 MeV were observed, including three levels for the first time. Proton spectroscopic factors were extracted for the first time for levels above the 33S+p threshold, spanning the energy range required for calculations of the thermonuclear 33S(p,gamma)34Cl rate in classical nova explosions. We have determined a new 33S(p,gamma)34Cl rate using a Monte Carlo method and have performed new hydrodynamic nova simulations to determine the impact on nova nucleosynthesis of remaining nuclear physics uncertainties in the reaction rate. We find that these uncertainties lead to a factor of less than 5 variation in the 33S(p,gamma)34Cl rate over typical nova peak temperatures, and variation in the ejected nova yields of S--Ca isotopes by less than 20%. In particular, the predicted 32S/33S ratio is 110 - 130 for the nova model considered, compared to 110 - 440 with previous rate uncertainties. As recent type II supernova models predict ratios of 130 - 200, the 32S/33S ratio may be used to distinguish between grains of nova and supernova origin.

A. Parikh; K. Wimmer; T. Faestermann; R. Hertenberger; J. Jose; H. -F. Wirth; C. Hinke; R. Krucken; D. Seiler; K. Steiger; K. Straub

2014-09-01

31

Isotopic 32S/33S ratio as a diagnostic of presolar grains from novae  

NASA Astrophysics Data System (ADS)

Measurements of sulphur isotopes in presolar grains can help to identify the astrophysical sites in which these grains were formed. A more precise thermonuclear rate of the 33S(p,?)34Cl reaction is required, however, to assess the diagnostic ability of sulphur isotopic ratios. We have studied the 33S(3He,d)34Cl proton-transfer reaction at 25 MeV using a high-resolution quadrupole-dipole-dipole-dipole magnetic spectrograph. Deuteron spectra were measured at ten scattering angles between 10° and 55°. Twenty-four levels in 34Cl over Ex=4.6-5.9 MeV were observed, including three levels for the first time. Proton spectroscopic factors were extracted for the first time for levels above the 33S + p threshold, spanning the energy range required for calculations of the thermonuclear 33S(p,?)34Cl rate in classical nova explosions. We have determined a new 33S(p,?)34Cl rate using a Monte Carlo method and have performed new hydrodynamic nova simulations to determine the impact on nova nucleosynthesis of remaining nuclear physics uncertainties in the reaction rate. We find that these uncertainties lead to a factor of ?5 variation in the 33S(p,?)34Cl rate over typical nova peak temperatures, and variation in the ejected nova yields of Ssbnd Ca isotopes by ?20%. In particular, the predicted 32S/33S ratio is 110-130 for the nova model considered, compared to 110-440 with previous rate uncertainties. As recent type II supernova models predict ratios of 130-200, the 32S/33S ratio may be used to distinguish between grains of nova and supernova origin.

Parikh, A.; Wimmer, K.; Faestermann, T.; Hertenberger, R.; José, J.; Wirth, H.-F.; Hinke, C.; Krücken, R.; Seiler, D.; Steiger, K.; Straub, K.

2014-10-01

32

On the Lx - L6 ?m ratio as a diagnostic for Compton-thick AGN  

NASA Astrophysics Data System (ADS)

As the mid-IR luminosity represents a good isotropic proxy of the AGN power, a low X-ray to mid-IR luminosity ratio is often claimed to be a reliable indicator of Compton-thick AGN. We assess the efficiency of the X-ray to mid-IR luminosity ratio diagnostic by examining the 12 ?m IRAS AGN sample (intrinsic L2-10 keV > 1042 erg s-1) for which high signal-to-noise ratio XMM-Newton observations are now available. We find that the vast majority (ten out of eleven) of the AGN that were classified as Compton-thick on the basis of X-ray spectroscopy by Brightman & Nandra have a low LX/L6 ?m luminosity ratio, i.e. lower than a few percent of the average AGN ratio, as is typical of reflection-dominated Compton-thick sources. At low LX/L6 ?m ratios, we also find a comparable number of AGN, most of which are heavily absorbed but not Compton-thick. This implies that although most Compton-thick AGN have low LX/L6 ?m ratios, at least in the local, Universe, the converse is not necessarily true. We then extend our analysis to higher redshifts. We perform the same analysis in the Chandra Deep Field South, for which excellent quality Chandra (4 Ms) and XMM-Newton (3 Ms) X-ray spectra are available. We derive accurate X-ray luminosities for Chandra sources using X-ray spectral fits, as well as 6 ?m luminosities from spectral energy distribution fits. We find in total eight AGN (intrinsic L2-10 keV > 1042 erg s-1) with low LX/L6 ?m ratios, after excluding one source where the 6 ?m emission primarily comes from star-formation. One of these sources has been already found to host a Compton-thick nucleus, while for another one at a redshift of z = 1.22 we argue it is most likely Compton-thick on the basis of its combined Chandra and XMM-Newton spectrum. In agreement with the low redshift sample, we find a large number of non Compton-thick "contaminants" with low X-ray to mid-IR luminosity ratios. Our results suggest that a low LX/L6 ?m ratio alone cannot help us to ascertain whether a Compton-thick AGN is present, albeit the majority of low LX/L6 ?m AGN are heavily obscured. More interestingly, the two most reliable Compton-thick AGN in the high redshift Universe have high LX/L6 ?m ratios, showing that this method cannot provide complete Compton-thick AGN samples.

Georgantopoulos, I.; Rovilos, E.; Akylas, A.; Comastri, A.; Ranalli, P.; Vignali, C.; Balestra, I.; Gilli, R.; Cappelluti, N.

2011-10-01

33

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

34

Laboratory Calibration of the 3d->2p Intensity Ratio for Opacity Diagnostics of High-Temperature Astrophysical Plasmas  

NASA Astrophysics Data System (ADS)

The n = 3->2 \\space({ ) 1}P1 and ({ ) 3}D1 resonance and intercombination lines are among the strongest spectral features found in L-shell X-ray spectra of neon-like ions, making them prime diagnostic candidates. Because the ({ ) 1}P1 line is a resonance line, it is preferentially scattered relative to the intercombination line and, therefore, the intensity ratio of these two lines in Fe XVII has been employed as an opacity diagnostic in solar observations. The line ratio is expected to play a similar role in CXO and XMM observations of hot plasmas. However, the reliability of this diagnostic depends heavily on an accurate intensity ratio for the optically thin case where no scattering occurs. Theoretical calculations of this ratio exhibit large variation. For example, in the case of Fe XVII, the calculated ratio varies between 2.7 and 4.7. This large variation prohibits the use of this ratio as an accurate diagnostic. In order to provide accurate values for use as optically thin benchmarks we have done a systematic laboratory study of this ratio for ions along the neon-like iso-electronic sequence between Cr XV and Kr XXXVII. Our measurements were done using the Electron Beam Ion Trap facility under conditions where the only line formation processes are electron impact excitation followed by radiative cascades. We have compared our measured ratios with those predicted by a distorted wave calculation. Our comparison shows a systematic difference between experiment and this particular theory of approximately 30%. Our laboratory calibration of this diagnostic ratio reduces the uncertainty in the optically thin value to 5% in the case of Fe XVII. This work was performed under the auspices of the U.S.D.o.E. under Contract No. W-7405-Eng-48 and supported by NASA HEA X-ray Astronomy Research and Analysis grant NAG5-5123 and work order W-19127.

Brown, G. V.; Beiersdorfer, P.; Liedahl, D. A.; Reed, K.; Utter, S. B.; Kahn, S. M.

1999-04-01

35

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

PubMed

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. PMID:21364704

Zhu, Xianlei; Fan, Zhihua Tina; Wu, Xiangmei; Jung, Kyung Hwa; Ohman-Strickland, Pamela; Bonanno, Linda J; Lioy, Paul J

2011-01-01

36

Diagnostic Value of Elastography Using Acoustic Radiation Force Impulse Imaging and Strain Ratio for Breast Tumors  

PubMed Central

Purpose The aim of this study was to determine whether the combination of B-mode ultrasonography (BUS), acoustic radiation force impulse (ARFI) elastography, and strain ratio (SR) provides better diagnostic performance of breast lesion differentiation than BUS alone. Methods ARFI elastography and SR evaluations were performed on patients with 157 breast lesions diagnosed by BUS from June to September 2013. BUS images were classified according to the Breast Imaging-Reporting and Data System. ARFI elastography was performed using Virtual Touch™ tissue imaging (VTI) and Virtual Touch™ tissue quantification (VTQ). In VTI mode, we evaluated the color-mapped patterns of the breast lesion and surrounding tissue. The lesions were classified into five categories by elasticity score. In VTQ mode, each lesion was assessed using shear wave velocity (SWV) measurements. SR was calculated from the lesion and comparable lateral fatty tissue. We compared the diagnostic performance of BUS alone and the combination of BUS, ARFI elastography, and SR evaluations. Results Among the 157 lesions, 40 were malignant and 117 were benign. The mean elasticity score (3.7±1.0 vs. 1.6±0.8, p<0.01), SWV (4.23±1.09 m/sec vs. 2.22±0.88 m/sec, p<0.01), and SR (5.69±1.63 vs. 2.69±1.40, p<0.01) were significantly higher for malignant lesions than benign lesions. The results for BUS combined with ARFI elastography and SR values were 97.5% sensitivity, 92.3% specificity, 93.6% accuracy, a 79.6% positive predictive value (PPV), and a 99.1% negative predictive value. The combination of the 3 radiologic examinations yielded superior specificity, accuracy, and PPV compared to BUS alone (p<0.01 for each). Conclusion ARFI elastography and SR evaluations showed significantly different mean values for benign and malignant lesions. Moreover, these two modalities complemented BUS and improved the diagnostic performance of breast lesion detection. Therefore, ARFI elastography and SR evaluations can be used as complementary modalities to make more accurate breast lesion diagnoses. PMID:24744801

Kim, Yoon Seok; Park, Jung Gu; Kim, Beom Su; Lee, Chung Han

2014-01-01

37

Ratios  

NSDL National Science Digital Library

This set of instructional materials and problems helps students understand ratios and proportions, starting with a simple review and progressing into the more advanced territory of similar triangles. The first three pages introduce ratios, proportions, and checking proportionality and the last four pages present mathematical and real-world problems for students to solve given their understanding of ratios and proportions.

Stapel, Elizabeth

2000-01-01

38

Diagnostic Role of Platelet Lymphocyte Ratio(PLR) in Pancreatic Head Masses.  

PubMed

Masses in and around pancreas constitute an important clinical entity in gastrointestinal surgical practice. Most common being adenocarcinoma of head of pancreas followed by inflammatory masses due to chronic pancreatitis. Accurate diagnosis is of central importance as therapeutic strategies range from observation to complete surgical removal including total pancreatectomy.Several tumor markers are available which could help in prognostication and diagnosis of carcinoma pancreas. Carbohydrate antigen 19-9(CA 19-9) is traditionally accepted best marker available. The role of new tumor marker platelet lymphocyte ratio (PLR) has been defined recently in prognostication of carcinoma pancreas. Role of PLR in diagnosing and its efficacy after combining it with CA 19-9 is not known. The aim of study was to assess the demographics of histologically proven neoplastic and inflammatory pancreatic head masses in our department. To assess the role of CA19-9 and platelet lymphocyte ratio(PLR) in determining nature of pancreatic head mass. Data consisted of histologically proven 45 patients .23 having head mass due to chronic pancreatitis and 22 because of neoplastic lesions. Demographics in terms of age, sex, previous pain episodes, presence of jaundice, history of alcohol intake were compared in both groups. Also tumor markers CA 19-9 and PLR individually and in combination were compared in both groups. Cancer pancreas significantly (p?diagnostic marker to differentiate between malignant and inflammatory head mass of pancreas. PMID:24426375

Miglani, Ripan K; Bhateja, Neeraj; Bhat, Ravi Shanker; Kumar, K V Ashok

2013-02-01

39

X-ray emission-line ratios in MG XI as electron temperature diagnostics for solar flares and active regions  

NASA Astrophysics Data System (ADS)

Electron temperature-sensitive emission-line ratios are derived via electron impact excitation rates for transitions in helium-like Mg XI, calculated with the R-matrix code. These ratios are found to be significantly different from earlier diagnostic calculations of Keenan et al. (1984, 1991), and lead to electron temperature estimates up to a factor of about 1.6 larger. Values of Te deduced from R1 and R2 ratios measured from solar flare and active region spectra obtained with the FCS on board the SMM satellite are consistent and in good agreement with temperatures estimated from the observed G ratios for these solar features. This provides support both for the validity of the theoretical R1 and R2 diagnostics, and for the FCS calibration curve in the wavelength region covering the Mg XI transitions 7.472-9.314 A.

Keenan, F. P.; Phillips, K. J. H.; Harra, L. K.; Conlon, E. S.; Kingston, A. E.

1992-07-01

40

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

41

Far-ir Pah Spectroscopy And The Identification Of An Individual Astronomical Pah Molecule  

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. With a new spectral window opening up in the far-IR, the quest for identifying a unique member of the interstellar PAH family has begun. To guide this search, the far-IR (> 20 ?m) spectra of different sets of PAHs are investigated using the NASA Ames PAH IR Spectroscopic Database - a large coherent set (> 600 spectra) of laboratory measured and DFT computed infrared spectra of PAHs from C10H8 to C130H28. These sets explore the influence of size, shape, charge and composition on the far-IR PAH spectrum. The far-IR is 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 for drums, these modes are considered to be very 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 the study of the far-IR PAH spectra of different sets as well as from the analysis of the `drumhead’ modes, some suggestions for an observing strategy are made.

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

2010-05-01

42

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

43

Polycyclic aromatic hydrocarbons (PAHs) in atmospheric PM2.5 and PM10 at a coal-based industrial city: Implication for PAH control at industrial agglomeration regions, China  

NASA Astrophysics Data System (ADS)

Eighteen polycyclic aromatic hydrocarbons (PAHs) in PM2.5 and PM10 are identified and quantified at five sites of E'erduosi in 2005 by GC-MS. Total PAH concentrations in PM2.5 and PM10 are in the ranges of 0.58-145.01 ng m- 3 and 5.80-180.32 ng m- 3 for the five sites, decreasing as coal-chemical base site (ZGE) > heavy industrial site (QPJ) > residential site with heavy traffic (DS) > suburban site surrounded by grassland (HJQ) > background site (QGN) for both PM2.5 and PM10. PAH concentrations in the coal-chemical base site are 250 and 31.1 times of those in the background site. Flu, Pyr, Chr, BbF, BeP, IND and BghiP are abundant for the coal-chemical base site, totally accounting for 75% of the PAH concentrations. 4, 5 and 6 rings PAHs are dominant, accounting for 88.9-94.2% and 90.5-94.1% of PAHs in PM2.5 and PM10, respectively. Combustion-derived PAH concentrations cover 42%-84% and 75%-82% of PAHs in PM2.5 and PM10, indicating large amounts of combustion sources existed for them in E'erduosi. PAH compositions between PM2.5 and PM10 are quite different from each other for sites with few human activities (HJQ and QGN) by coefficient of divergence analysis. Results obtained from principal component analysis and diagnostic ratios indicate that coal combustion, vehicle emission, wood combustion and industrial processes are the main sources for PAHs in E'erduosi. According to BaP equivalent concentration, the potential health risk of PAHs in PM2.5 at the two industrial sites ZGE and QPJ are 537 and 460 times of those for the background site. And they are 4.3 and 3.7 times of those for the residential site. The potential PAH pollution in particles at other industrial agglomeration regions that occurred in China in recent years should be paid attention by the local government.

Wu, Di; Wang, Zongshuang; Chen, Jianhua; Kong, Shaofei; Fu, Xiao; Deng, Hongbing; Shao, Guofan; Wu, Gang

2014-11-01

44

PAHs and the Universe: A Symposium to Celebrate the 25th Anniversary of the PAH Hypothesis  

NASA Astrophysics Data System (ADS)

Driven by ground-based, airborne, and IRAS observations, the PAH hypothesis was first formulated in the mid-eighties: the widespread emission features in the 3-13 ?m range are due to UV-pumped, IR-fluorescence by large Polycyclic Aromatic Hydrocarbon molecules. These molecules are a ubiquitous component of the interstellar medium both in local galaxies as well as out to redshifts of ~3 and probably beyond, play an important role in its physical and chemical characteristics, and form a key link between small hydrocarbon species and large carbonaceous grains. This book gathers contributions that reflect the evolution of the field over the last 25 years, taking advantage of IR space missions - ISO, Spitzer and AKARI - and of dedicated experimental and quantum-chemical studies. We have now reached a stage where we can develop these mid-infrared features as diagnostic tools to study star formation processes, protoplanetary disks as well as galaxy assemblage in the early Universe. The current Herschel/Planck area opens the possibility to better characterize the mid-IR carriers through their contribution to the far-IR and mm emissions. Still, much effort is required before we will fully understand the formation and nature of interstellar PAHs and their role in the Universe. Physical chemists can play an important role in driving this field. This book aims at discussing the state-of-the-art of the PAH hypothesis and to chart the future in this interdisciplinary field. It highlights the various aspects of interstellar PAHs: - Rich IR spectra of interstellar PAHs - PAHs and star formation in the near and far Universe - The lifecycle of PAHs in space - PAHs in regions of planet formation - PAHs and carbonaceous grains & Solar system materials - The role of PAHs in the interstellar medium

Joblin, C.; Tielens, A. G. G. M.

2011-06-01

45

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

46

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

47

Conversion of the 6302 / 6301 Stokes V Line Ratio to the 5250 / 5247 Ratio for the Diagnostics of Quiet-Sun Magnetic Fields  

NASA Astrophysics Data System (ADS)

Observations in the "green" spectral lines Fe I 5247.06 and 5250.22 Å and in the "red" lines Fe I 6301.50 and 6302.50 Å are widely used to explore the properties of solar magnetic fields. The green line pair was introduced in 1973 as part of the line-ratio technique, which has been a powerful tool for investigations of intrinsic magnetic field properties at spatially unresolved scales (magnetic flux tubes with kG strengths). The red line pair has recently played a major role for magnetic-field diagnostics due to the large amount of high-quality data provided by the Hinode space observatory. These red lines however differ not only in the values of their Landé factors, but also in their line-formation properties, with the consequence that the magnetic-field information in their line ratio gets tangled up with thermodynamic effects. In contrast, as the green Fe I 5247.06 and 5250.22 Å lines differ only in their Landé factors, the magnetic field effects become cleanly separated from the thermodynamics, which allows the intrinsic magnetic field parameters to be extracted without ambiguties. The red and green line-ratio values are however statistically correlated. By determining the statistical regression function that relates them, it becomes possible to convert the "contaminated" and ambiguous red line ratio into the green line ratio, with which a reliable direct interpretation in terms of intrinsic field strengths is possible. To determine how the two line ratios are related we have made Stokesmeter observations in these four spectral lines with two solar instruments equipped with high-precision spectropolarimeters, ZIMPOL-3 at IRSOL (Locarno, Switzerland), and the STOP telescope at the Sayan Solar Observatory (Irkutsk, Russia). Most of the obtained results are based on IRSOL observations of quiet-sun magnetic fields. In the case of STOP the full-disk magnetograms of large-scale solar magnetic fields are analyzed. A major advantage at IRSOL is the possibility to observe the green and red line pairs simultaneously on the same CCD chip. We have determined how the two line ratios decrease with increasing Stokes V amplitude and increase with increasing distance from disk center. The relation that allows us to convert the observed values for the red line ratio into the corresponding values for the green line ratio has been found and given in analytical form.

Demidov, M. L.; Stenflo, J. O.; Bianda, M.; Ramelli, R.

2014-10-01

48

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 20 ng CALUX-TEQ/g dw) than those from a rural site (2 to 13, mean 5 ng 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

49

Principles of microbial PAH-degradation in soil  

Microsoft Academic Search

Interest in the biodegradation mechanisms and environmental fate of polycyclic aromatic hydrocarbons (PAHs) is motivated by their ubiquitous distribution, their low bioavailability and high persistence in soil, and their potentially deleterious effect on human health. Due to high hydrophobicity and solid–water distribution ratios, PAHs tend to interact with non-aqueous phases and soil organic matter and, as a consequence, become potentially

Anders R. Johnsen; Lukas Y. Wick; Hauke Harms

2005-01-01

50

Spatial and temporal variation of freely dissolved PAHs in an urban river undergoing Superfund remediation  

PubMed Central

Urban rivers with a history of industrial use can exhibit spatial and temporal variations in contaminant concentrations that may significantly affect risk evaluations and even the assessment of remediation efforts. Concentrations of 15 biologically available priority pollutant polycyclic aromatic hydrocarbons (PAHs) were measured over five years along 18.5 miles of the lower Willamette River using passive sampling devices and HPLC. The study area includes the Portland Harbor Superfund megasite with several PAH sources including remediation operations for coal tar at RM 6.3 west and an additional Superfund site, McCormick and Baxter, at RM 7 east consisting largely of creosote contamination. Study results show that organoclay capping at the McCormick and Baxter Superfund Site reduced PAHs from a pre-cap average of 440 ± 422 ng/L to 8 ± 3 ng/L post-capping. Results also reveal that dredging of submerged coal tar nearly tripled nearby freely dissolved PAH concentrations. For apportioning sources, fluoranthene/ pyrene and phenanthrene/anthracene diagnostic ratios from passive sampling devices were established for creosote and coal tar contamination and compared to published sediment values. PMID:19174872

Sower, GJ; Anderson, K.A.

2014-01-01

51

O2\\/CO2 emission ratios as a diagnostic for source identification?  

Microsoft Academic Search

High-precision measurements of atmospheric oxygen play an increasingly important role in our understanding of the global carbon cycle. In combination with CO2-measurements, they allow the partitioning of global oceanic and terrestrial sinks of anthropogenic CO2. In addition, local source\\/sink patterns can be identified from the combination of O2 and CO2-signals since different combustion processes have different oxidative ratios (OR= -O2\\/CO2).

J. Steinbach; C. Gerbig

2009-01-01

52

Distribution and characteristics of PAHs in sediments from the marine environment of Korea.  

PubMed

To assess the contamination of polycyclic aromatic hydrocarbons (PAHs) in the marine environment of Korea, 117 sediment samples along the coast were collected and analyzed. This study provides perspectives on concentration ranges and on geographic distributions of PAHs. Sum of 16 PAHs concentrations are in the range of 8.80-18500 ng/g dry weight. Industrialized and urbanized region showed high level of PAHs contamination. When compared with nationwide monitoring results of USA and UK, concentration of total PAHs are in the order of UK>US>this study. Major PAHs sources inferred from diagnostic indices and statistical approach were both pyrogenic and petrogenic. In coastal and offshore sediments of Korea, 7.76% sites had a mean PAH ERL quotient >1.0, indicating the potential to cause adverse effects in sensitive species. Youngil Bay was recognized as highly contaminated with PAHs, and recommended to be managed with special plan. PMID:17267023

Yim, U H; Hong, S H; Shim, W J

2007-05-01

53

Spatially Resolved PAH Emission in Nearby, Low-Metallicity Galaxies  

NASA Astrophysics Data System (ADS)

Low-resolution mid-infrared Spitzer spectra are presented for three nearby, low-metallicity dwarf galaxies (NGC 55, IC 5152 and NGC 3109) for the purpose of examining polycyclic aromatic hydrocarbon (PAH) emission on a spatially resolved basis. The sample closely brackets the 12 + log(O/H) 8 transition metallicity below which PAH emission strength empirically drops, allowing examination of the processes which contribute to this shift. Fitting the spectra produced quantitative line strengths and flux values for PAH features and atomic lines. Extensive ancillary data allow us to examine the changes in environment (for example, radiation field intensity) and PAH emission strength over scales from 10 to 50 pc. Comparison of the 8 ?m/11.3 ?m PAH ratio on a spatial basis indicates that these features scale together, and that this ratio shows only minor scatter across the observed region of the galaxies.

Haynes, Korey; Cannon, J.; Skillman, E. D.; Jackson, D.; Gehrz, R.

2010-01-01

54

Bioavailability of PAHs: effects of soot carbon and PAH source.  

PubMed

The bioavailability of 38 individual polycyclic aromatic hydrocarbon (PAH) compounds was determined through calculation of biota-sediment-accumulation factors (BSAF). BSAF values were calculated from individual PAH concentrations in freshwater mussel, marine clam, and sediment obtained from field and laboratory bioaccumulation studies. Sediment that was amended with different types of soot carbon (SC) was used in some of the bioaccumulation experiments. BSAF values for petrogenic PAH were greater than those for pyrogenic PAH (e.g., 1.57 +/- 0.53 vs 0.25 +/- 0.23, respectively), indicating that petrogenic PAH are more bioavailable than pyrogenic PAH (p < 0.05). This trend was consistent among marine and freshwater sites. Increased SC content of sediment resulted in a linear decrease in the bioavailability of pyrogenic PAHs (r2 = 0.85). The effect of increasing SC content on petrogenic PAH was negligible. SC was considered as an additional sorptive phase when calculating BSAF values, and using PAH-SC partition coefficients from the literature, we obtained unreasonably large BSAF values for all petrogenic PAH and some pyrogenic PAH. This led us to conclude that a quantitative model to assess bioavailability through a combination of organic carbon and soot carbon sorption is not applicable among field sites with a wide range of soot carbon fractions and PAH sources, at least given our current knowledge of PAH-SC partitioning. Our data offer evidence that many factors including analysis of a full suite of PAH analytes, PAH hydrophobicity, sediment organic carbon content, sediment soot carbon content, and PAH source are importantto adequately assess PAH bioavailability in the environment. PMID:15112803

Thorsen, Waverly A; Cope, W Gregory; Shea, Damian

2004-04-01

55

Neutron spectroscopy as a fuel ion ratio diagnostic: Lessons from JET and prospects for ITER  

SciTech Connect

The determination of the fuel ion ratio n{sub t}/n{sub d} in ITER is required at a precision of 20%, time resolution of 100 ms, spatial resolution of a/10, and over a range of 0.016 keV and for n{sub T}/n{sub D}<0.6. A crucial issue is the signal-to-background situation in the measurement of the weak 2.5 MeV emission from DD reactions in the presence of a background of scattered 14 MeV DT neutrons. Important experimental input and corroboration for this assessment are presented from the time-of-flight neutron spectrometer at JET where the presence of a strong component of backscattered neutrons is observed. Neutron emission components on ITER due to beam-thermal and tritium-tritium reactions can further enhance the prospects for NES.

Ericsson, G.; Conroy, S.; Gatu Johnson, M.; Andersson Sunden, E.; Cecconello, M.; Eriksson, J.; Hellesen, C.; Sangaroon, S.; Weiszflog, M. [Department of Physics and Astronomy, Uppsala University (EURATOM-VR Association), SE-75120 Uppsala (Sweden); Collaboration: JET EFDA Contributors

2010-10-15

56

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 87,880 ng/g dry weight in topsoil, from 4739 to 59,314 ng/g dry weight in SS, and from 2137 to 9037 ng/L in groundwater, with mean values of 17,174 ng/g, 11,990 ng/g and 5020 ng/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

57

Pulmonary Arterial Hypertension (PAH)  

MedlinePLUS

... a strain on the heart. There is no cure for PAH, but several medications are available to treat symptoms. In-Depth ... Flu Season - Time to Get Vaccinated October 8, 2014 Depression and Lung Disease October 7, 2014 Enterovirus D68 - ...

58

Polycyclic Aromatic Hydrocarbons and their Molecular Diagnostic Ratios in Airborne Particles (PM10) Collected in Rio de Janeiro, Brazil  

Microsoft Academic Search

Atmospheric polycyclic aromatic hydrocarbons (PAHs) were determined in particulate matter (PM10) collected in a suburban area\\u000a with industrial and vehicular emissions in the Metropolitan Area of Rio de Janeiro City (Brazil). A total of 22 samples were\\u000a collected between March and August 2005 by means of a high volume PM10 sampler. The particulate matter contained in the filters\\u000a was extracted

Simone Lorena Quiterio; Graciela Arbilla; Glauco Favilla Bauerfeldt; Josino Costa Moreira

2007-01-01

59

Relation between PAH and black carbon contents in size fractions of Norwegian harbor sediments.  

PubMed

Distributions of total organic carbon (TOC), black carbon (BC), and polycyclic aromatic hydrocarbons (PAH) were investigated in different particle size fractions for four Norwegian harbor sediments. The total PAH (16-EPA) concentrations ranged from 2 to 113 mg/kg dry weight with the greatest fraction of PAH mass in the sand fraction for three of the four sediments. TOC contents ranged from 0.84% to 14.2% and BC contents from 0.085% to 1.7%. This corresponds to organic carbon (OC = TOC - BC) contents in the range of 0.81-14% and BC:TOC ratios of 1.3-18.1%. PAH isomer ratios suggested that the PAH in all four sediments were of pyrogenic origin. Furthermore, stronger correlations between PAH versus BC (r2 = 0.85) than versus OC (r2 = 0.15) were found. For all size fractions and bulk sediments, the PAH-to-BC ratios for the total PAHs were on average 6+/-3 mg PAH/g BC. These results suggest that PAH distributions were dominated by the presence of BC, rather than OC. As sorption to BC is much stronger than sorption to OC, this may result in significantly lower dissolved concentrations of PAH than expected on the basis of organic carbon partitioning alone. PMID:16249047

Oen, Amy M P; Cornelissen, Gerard; Breedveld, Gijs D

2006-05-01

60

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

61

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

62

Atmospheric polycyclic aromatic hydrocarbons and isomer ratios as tracers of biomass burning emissions in Northern India.  

PubMed

Emission from large-scale post-harvest agricultural-waste burning (paddy-residue burning during October-November and wheat-residue burning in April-May) is a conspicuous feature in northern India. The poor and open burning of agricultural residue result in massive emission of carbonaceous aerosols and organic pollutants to the atmosphere. In this context, concentrations of atmospheric polycyclic aromatic hydrocarbons (PAHs) and their isomer ratios have been studied for a 2-year period from a source region (Patiala: 30.2°N; 76.3°E) of two distinct biomass burning emissions. The concentrations of 4-6 ring PAHs are considerably higher compared to 2-3 ring PAHs in the ambient particulate matter (PM2.5). The crossplots of PAH isomer ratios, fluoranthene?/?(fluoranthene?+?pyrene) and indeno[1,2,3-cd]pyrene/(indeno[1,2,3-cd]pyrene?+?benzo[g,h,i]perylene) for two biomass burning emissions, exhibit distinctly different source characteristics compared to those for fossil-fuel combustion sources in south and south-east Asia. The PAH isomer ratios studied from different geographical locations in northern India also exhibit similar characteristics on the crossplot, suggesting their usefulness as diagnostic tracers of biomass burning emissions. PMID:24442960

Rajput, Prashant; Sarin, M M; Sharma, Deepti; Singh, Darshan

2014-04-01

63

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

64

PAHs in PM2.5 in Zhengzhou: concentration, carcinogenic risk analysis, and source apportionment.  

PubMed

Ambient air samples were collected at two different locations between 2011 and 2012 in Zhengzhou, China in order to assess the concentration level, health risks, as well as the sources of polycyclic aromatic hydrocarbons (PAHs) in particulate matter (PM2.5). The mean annual levels of PM2.5 observed at industry site and residential site were 172?±?121 and 160?±?72 ?g m(-3), respectively, which were about five times the annual value of proposed PM2.5 standard (35 ?g m(-3)) in China. The PM2.5 in all daily samples (n?=?47) exceeds the proposed PM2.5 standard in China (75 ?g m(-3)) at both industrial and residential sites. Seasonal variations of PM2.5 showed a clear trend of winter?>?autumn?>?spring?>?summer at both sites. The total concentrations of 16 PM2.5-associated PAHs ranged from 61?±?51 to 431?±?281 and 38?±?25 to 254?±?189 ng m(-3), with mean value of 176?±?233 and 111?±?146 ng m(-3) at industry and residential sites, respectively. The major species were fluoranthene, pyrene, chrysene, benzo[b]fluoranthene and benzo[k]fluoranthene, and the concentration levels of PAHs in PM2.5 were higher in winter than those of other seasons at both sites. The annual mean values of toxicity equivalency concentrations of ?16PAHs in PM2.5 were 22.8 and 13.5 ng m(-3) in industry and residential area, respectively. In this study, the risk level of adult citizens through inhalation exposure to PAHs was calculated. The average estimates of lifetime inhalation cancer risks were approximately 8.9?×?10(-7) and 6.3?×?10(-7) for industry and residential sites, respectively. The main sources of 16 PAHs from both diagnostic ratios and principle component analysis identified as vehicular emissions and coal combustion. PMID:25060861

Wang, Jia; Geng, Ning Bo; Xu, Yi Fei; Zhang, Wen Ding; Tang, Xiao Yan; Zhang, Rui Qin

2014-11-01

65

The distribution and origin of PAHs over the Asian marginal seas, the Indian, and the Pacific Oceans: Implications for outflows from Asia and Africa  

NASA Astrophysics Data System (ADS)

samples were collected aboard the R/V Dayang Yihao from 8 January to 7 August 2007 to investigate the geographical distribution of polycyclic aromatic hydrocarbons (PAHs) over oceans and to assess their continental origins. The highest concentrations were found over the marginal seas in Asia, especially the East and South China Seas, indicating that China is a top source of emissions into the marine atmosphere in the areas monitored on this cruise. PAH concentrations over the west oceanic region in the South Indian Ocean were noticeably higher than in other areas of the Indian Ocean, most likely because air masses from Africa, the Arabian Sea, and the Bay of Bengal exert a negative impact on those regions through long-range atmospheric transport. The PAH isomer ratio values varied over the oceans that were impacted by continental sources but remained relatively uniform over most of the remote oceans. Using diagnostic ratio analysis, we found PAHs emitted from China were mainly associated with biomass/coal burning. The measurements of levoglucosan were consistent with the results mentioned above. The western part of the South Indian Ocean atmosphere was likely affected by wildfire emissions from Africa, while the northern part was by petroleum combustion, biofuel, and wildfire burning, because the winter monsoon most likely carries aerosol from the Arabian Peninsula and India across the equator. Using the monthly images of fire activity and aerosol optical depth, it can be confirmed biomass burning from Africa can significantly influence the aerosol over the Indian Ocean.

Liu, Junwen; Xu, Yue; Li, Jun; Liu, Di; Tian, Chongguo; Chaemfa, Chakra; Zhang, Gan

2014-02-01

66

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

67

Levels and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) in superficial sediment from 15 Italian marine protected areas (MPA).  

PubMed

Surface sediment from 15 Italian marine protected areas (MPA) were analysed for polycyclic aromatic hydrocarbons (PAHs). The organic carbon percentage was also determined. Total PAH concentrations (ng g?¹ d.w.) ranged from 0.71 (Penisola del Sinis) to 1550 (Miramare). Individual PAH analysis showed that three and four rings PAHs were the most frequently detected isomers and accounted for 60-70% of the PAH total concentrations. PAH ratio analysis showed a prevalence of pyrolytic PAH origin at most of the MPAs with exception of Porto Cesareo and Ustica where a petrogenic origin was detected. Results for organic carbon percentages ranged from 0.3% (Capo Rizzuto) to 2% (Punta Campanella). These results are comparable to other Mediterranean marine environments. However, our results shows that some MPAs, such as Miramare, Porto Cesareo, Isola Capo Rizzuto and Punta Campanella, are subject to strong pressure from urban and industrial activities where high PAH levels were detected. PMID:21310440

Perra, Guido; Pozo, Karla; Guerranti, Cristiana; Lazzeri, Denise; Volpi, Valerio; Corsolini, Simonetta; Focardi, Silvano

2011-04-01

68

Natural background and anthropogenic inputs of polycyclic aromatic hydrocarbons (PAH) in sediments of South-Western Barents Sea.  

PubMed

Polycyclic aromatic hydrocarbons (PAH) were measured in sediment cores from 13 locations in South-Western Barents Sea as part of a detailed study of the Norwegian seabed under the MAREANO program. The generally low PAH levels found, an average around 200 ng g(-1) dry weight for sum PAH, indicate low inputs of petroleum hydrocarbons to the marine environment in the area. Differences in PAH composition and various PAH ratios indicate a natural, mostly petrogenic origin of PAH in sediments from the open sea locations, while the fjord locations show higher pyrogenic PAH contents with an increase towards upper sediment layers, indicating low inputs from human activities. Petrogenic PAH levels increase in deeper sediments at open sea locations, also when normalised to total organic carbon (TOC) contents, suggesting natural leakages of oil-related hydrocarbons in the area. PMID:19643470

Boitsov, Stepan; Jensen, H K B; Klungsøyr, Jarle

2009-12-01

69

Source identification of polycyclic aromatic hydrocarbons (PAHs) in sediment samples from the northern part of the Persian Gulf, Iran.  

PubMed

Samples of surface sediments from the Iranian coast of the Persian Gulf were examined to determine the levels and sources of 15 polycyclic aromatic hydrocarbons (PAHs). Samples were collected from 30 sampling sites and analyzed for PAHs by gas chromatography-mass spectrometry (GC-MS). Total concentrations of PAHs ranged from 93 to 4,077 ng g(-1) dry weight. The PAH composition from 30 sampling sites was dominated by four-ring PAH compounds. Molecular indices based on the ratios of PAH concentrations were used to differentiate PAHs from pyrolitic to petrogenic and mixed origins. The results suggested that the main sources of PAHs in sediments from the studied region were mixed pyrolitic and petrogenic. Furthermore, benthic organisms in most of the investigated areas were not at ecotoxicological risk, according to the results from the effects range low (ERL)/effects range median (ERM) techniques suggested by the US Sediment Quality Guidelines (SQGs). PMID:25023748

Mirza, Roozbeh; Mohammadi, Mehdi; Faghiri, Iraj; Abedi, Ehsan; Fakhri, Ali; Azimi, Ali; Zahed, Mohammad Ali

2014-11-01

70

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. PMID:20485462

Kim, Daekyun; Young, Thomas M.

2009-01-01

71

A terminal of PAH evolution  

NASA Astrophysics Data System (ADS)

Evolved stars supply first organic materials into space. The organic materials evolve and alter to form more complex organic molecules before incorporation into the star formation stage. Polycyclic aromatic hydrocarbons (PAH) are most plausible molecules abundantly produced within the gas ejected from evolved stars. A single aromatic ring, benzene, can be made from acetylene molecules (Woods et al. 2002; Woods et al. 2003). Benzene grows to larger PAHs by the abstraction of ring hydrogen and further interaction with acetylene (Bittner & Howard 1981; Frenklach et al. 1984). During the growth of PAH molecules, and as they move away from the central star, larger PAHs coagulate to form PAH grains (Rapacioli et al. 2005). The progression of organic materials after PAH grains has been unknown. We performed simulation experiments to find their evolutional process after PAH grains and demonstrate the possible formation site, process, and starting material. Condensation experiments are involved exposing a vapor phase to plasma to form carbonaceous grains, a situation that exists ubiquitously in space. Benzene was introduced into the He plasma. After the experiment, brown- to yellowish-colored materials were obtained by the decomposition of benzene due to polymerization. After transmission electron microscope observation, we found formation of organic grains with cavity in their center. The hollow interior could be formed by coagulation of atomic vacancies, produced by electronic excitation and/or knock-out of carbon atoms following irradiation by plasma particles. Similar extraterrestrial organic grains, called organic globules, have been found abundantly in several carbonaceous chondrites, which often have a cavity in their center (Nakamura-Messenger et al. 2006). The result suggests that organic globules are possibly the final products in the evolution of carbonaceous matter from acetylene, benzene to PAH in ejecta gas from evolved stars, i.e., abundant PAH molecules around evolved stars may connect to the organic globules.

Kimura, Yuki; Saito, M.

2010-01-01

72

Particle size distribution of n-alkanes and polycyclic aromatic hydrocarbons (PAHS) in urban and industrial aerosol of Algiers, Algeria.  

PubMed

The distribution of ambient air n-alkanes and polycyclic aromatic hydrocarbons (PAHs) associated to particles with aerodynamic diameters lesser than 10 ?m (PM(10)) into six fractions (five stages and a backup filter) was studied for the first time in Algeria. Investigation took place during September of 2007 at an urban and industrial site of Algiers. Size-resolved samples (<0.49, 0.49-0.95, 0.95-1.5, 1.5-3.0, 3.0-7.2, and 7.2-10 ?m) were concurrently collected at the two sampling sites using five-stage high-volume cascade impactors. Most of n-alkanes (~72 %) and PAHs (~90 %) were associated with fine particles ? 1.5 ?m in both urban and industrial atmosphere. In both cases, the n-alkane contents exhibited bimodal or weakly bimodal distribution peaking at the 0.95-1.5-?m size range within the fine mode and at 7.3-10 ?m in the coarse mode. Low molecular weight PAHs displayed bimodal patterns peaking at 0.49-0.95 and 7.3-10 ?m, while high molecular weight PAHs exhibited mono-modal distribution with maximum in the <0.49-?m fraction. While the mass mean diameter of total n-alkanes in the urban and industrial sites was 0.70 and 0.84 ?m, respectively, it did not exceed 0.49 ?m for PAHs. Carbon preference index (~1.1), wax% (10.1-12.8), and the diagnostic ratios for PAHs all revealed that vehicular emission was the major source of these organic compounds in PM(10) during the study periods and that the contribution of epicuticular waxes emitted by terrestrial plants was minor. According to benzo[a]pyrene-equivalent carcinogenic power rates, ca. 90 % of overall PAH toxicity across PM(10) was found in particles ? 0.95 ?m in diameter which could induce adverse health effects to the population living in these areas. PMID:23982823

Ladji, R; Yassaa, N; Balducci, C; Cecinato, A

2014-02-01

73

PAH characteristics and genotoxicity in the ambient air of a petrochemical industry complex  

SciTech Connect

Polycyclic aromatic hydrocarbons (PAHs) samples, at four sampling sites, in the ambient air of petrochemical plants were collected by several PS-1 samplers from October 1993 to July 1994 in a petrochemical complex area located in southern Taiwan. In addition, the genotoxicity of the PAH samples were investigated by the Ames Salmonella/microsomal assay system. The winter/summer ratios of total-PAH composition were 0.60, 1.39, 2.97, and 1.28 for sites A, B, C, and D, respectively. This result implied that wind direction is the most significant parameter affecting the total-PAH composition in these four sampling sites. Sampling sites B, C, and D were located on the downwind side of the petrochemical plant and gave higher total-PAH composition than those of sampling site A. Particle phase PAHs had higher mutagenicity than those in the gas phase.

Tsai, Jiun-Horng; Peng, Being-Hwa; Lee, Ding-Zang; Lee, Ching-Chang [National Cheng Kung Univ., Tainan (China)] [National Cheng Kung Univ., Tainan (China)

1995-05-01

74

Vertical distribution and source identification of polycyclic aromatic hydrocarbons (PAHs) in southwest of the Caspian Sea: Most petrogenic events during the late Little Ice Age.  

PubMed

In this study, 75 samples of two (210)Pb-dated cores from the southwest of the Caspian Sea were analysed for 30 compounds of polycyclic aromatic hydrocarbons (PAHs). The TPAH29 flux of the last six centuries ranged from 16.3 to 177.3 and 22.3 to 426.2ngcm(-2)y(-1) in the Rezvanshahr and Anzali core sediments, respectively. Prior to 1840, four distinct maxima in PAH fluxes (61-426.2ngcm(-2)y(-1)) with a low weathered petrogenic pattern were found in each of the core sediments. Simultaneity of distinct peaks of PAH fluxes before 1840 and Caspian Sea level high-stands during the Little Ice Age (LIA), revealed the high importance of this phenomenon in washing and transport of land-based oil pollution into the Caspian Sea. An overall increase in some diagnostic ratios (Flu/202, IP/276 and BaA/228), especially after 1940, indicated increase of pyrogenic PAHs as a result of industrial development in the catchment area. PMID:25131419

Varnosfaderany, Mohammad Nemati; Bakhtiari, Alireza Riyahi; Gu, Zhaoyan; Chu, Guoqiang

2014-10-15

75

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

76

Indoor PAHs at schools, homes and offices in Rome, Italy  

NASA Astrophysics Data System (ADS)

Indoor and outdoor concentrations of polycyclic aromatic hydrocarbons (PAHs) associated with PM2.5 particles were monitored in three microenvironments (schools, homes and offices) in the city of Rome, Italy, between winter 2011 and summer 2012. Molecular signatures and indoor/outdoor concentration ratios of PAHs were investigated, with special emphasis on carcinogenic congeners. At indoor locations, total PAHs ranged, on average, from 1.8 to 8.4 ng/m3 in winter and from 0.30 to 1.35 ng/m3 in spring/summer. Outdoors, total PAH concentrations were found to reach 6.3-17.9 ng/m3 in winter and 0.42-1.74 ng/m3 in spring-summer. Indoors, the concentration of benzo[a]pyrene (BaP) was as high as 1.1 ng/m3 in winter and below 0.1 ng/m3 in the warm season, independently of site type; the yearly average remained below the European guideline value. The indoor/outdoor concentration ratios of individual compounds were lower than one for most of congeners, suggesting that outdoor sources were predominant. Nonetheless, the percentages of PAH compounds changed with sites and seasons; in particular, in spring/summer, the concentration of BaP at our sites was more than twice that recorded at the regional network stations.

Romagnoli, P.; Balducci, C.; Perilli, M.; Gherardi, M.; Gordiani, A.; Gariazzo, C.; Gatto, M. P.; Cecinato, A.

2014-08-01

77

Selecting a reduced suite of diagnostic ratios calculated between petroleum biomarkers and polycyclic aromatic hydrocarbons to characterize a set of crude oils.  

PubMed

A set of 34 crude oils was analysed by GC-MS (SIM mode) and a suite of 28 diagnostic ratios (DR) calculated. They involved 18 ratios between biomarker molecules (hopanes, steranes, diasteranes and triaromatic steroids) and 10 quotients between polycyclic aromatic hydrocarbons. Three unsupervised pattern recognition techniques (i.e., principal components analysis, heatmap hierarchical cluster analysis and Kohonen neural networks) were employed to evaluate the final dataset and, thus, ascertain whether the crude oils grouped as a function of their geographical origin. In addition, an objective variable selection procedure based on Procrustes Rotation was undertaken to select a reduced set of DR that comprised for most of the information in the original data without loosing relevant information. A reduced set of four DR (namely; TA21, D2/P2, D3/P3 and B(a)F/4-Mpy) demonstrated to be sufficient to characterize the crude oils and the groups they formed. PMID:21081235

Fernández-Varela, R; Andrade, J M; Muniategui, S; Prada, D

2010-12-24

78

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

79

The NASA Ames PAH IR Spectroscopic Database V 2.0 - Spectroscopic Fitting Tools and More  

NASA Astrophysics Data System (ADS)

Polycyclic Aromatic Hydrocarbons (PAHs), omnipresent across the Universe, play an intrinsic part in the formation of stars, planets and possibly even life itself. While PAH infrared (IR) emission features are now routinely used as tracers of star formation and redshift indicators for distant, dust obscured, galaxies, there is a wealth of information in the PAH spectra that remains untapped. This information reveals subtle details about the PAH population within an object, details which, in turn, probe local conditions in the object. We continue to develop the experimental and computational PAH spectra collected at NASA Ames into such diagnostics. This coherent, large (some 700) collection of IR spectra from the single ring aromatic molecule benzene to PAHs containing 386 carbon atoms is now part of the NASA Ames PAH IR Spectroscopic Database (PAHdb). PAHdb can be accessed at www.astrochemistry.org/pahdb, where its contents can be browsed and/or downloaded along with advanced on- and off-line tools that allow astronomers to work with the spectroscopic data. Since it's initial release in 2010, new spectra have been added, the website has been improved and the tools expanded. It is now possible to upload astronomical spectra to the website in several common formats e.g., fits and VOTable, and fit them with the spectra in PAHdb, several PAH emission models are also available with which one can compute the emission expected from complex PAH mixtures, animations of the molecular vibrations corresponding to individual modes are available, etc. These newly added tools, together with the enlarged set of PAH spectra, allow astronomers to analyze and probe the conditions in a multitude of very different astronomical objects in new ways. This talk summarizes the updated contents of PAHdb, the improved website with its expanded tools and demonstrates fitting an astronomical spectrum. If time allows, using these spectral fitting techniques to analyze the Spitzer-IRS map of the reflection nebula NGC7023 will be demonstrated, showcasing the variations in PAH subpopulations.

Boersma, Christiaan; Allamandola, L. J.; Bauschlicher, C.; Ricca, A.; Mattioda, A.; Cami, J.; Peeters, E.; Sanchez, F.; Puerta, G.; Hudgins, D. M.

2013-01-01

80

Updated listing of haplotypes at the human phenylalanine hydroxylase (PAH) locus  

SciTech Connect

Analysis of mutant PAH chromosomes has identified approximately 60 different single-base substitutions and deletions within the PAH locus. Nearly all of these molecular lesions are in strong linkage disequilibrium with specific RFLP haplotypes in different ethnic populations. Thus, haplotype analysis is not only useful for diagnostic purposes but is proving to be a valuable tool in population genetic studies of the origin and spread of phenylketonuria alleles in human populations. PCR-based methods have been developed to detect six of the eight polymorphic restriction sites used for determination of RFLP haplotypes at the PAH locus. A table of the proposed expanded haplotypes is given.

Eisensmith, R.C.; Woo, S.L.C. (Baylor College of Medicine, Houston, TX (United States))

1992-12-01

81

PAH composition and potential sources for sediment samples from the Beaufort and Barents Seas  

SciTech Connect

Sediment grabs and cores have been analyzed for parent and alkyl PAHs (polycyclic aromatic hydrocarbons) and time horizons have been determined using radionuclide distributions. PAH concentrations are significantly higher (2 to 20 times) in the Mackenzie River and the Beaufort Sea than in sediment from the Barents Sea. Concentrations exhibit little change between the Mackenzie River and shelf, but decrease slightly at the shelf edge. Barents Sea sediments have the highest concentrations in the southeast (near the major rivers), are slightly lower in the north and west of the sea, and are lowest near Novaya Zemlya. In most cases there is little change in PAH composition between surface layers and deeper sediments (10--20 cm) that contain no detectable bomb radionuclides. PAH profiles and principal components analysis (PCA) clearly distinguish PAH sources for the Arctic. Barents Sea sediments are most similar to Arctic atmospheric aerosols in their PAH molecular-mass ratios and PCA projections. Samples from the west and north sides of the Barents Sea are consistent with a petroleum source, while samples from other areas have combustion sources. Anthropogenic combustion inputs are particularly important in the southern Barents Sea, whereas natural inputs are important to the Beaufort Sea. The uniformity and the relatively high concentration of Beaufort Sea PAHs reflects a river dominated input of natural PAHs which tends to overwhelm any anthropogenic sources. Despite the greater anthropogenic influence in the Barents Sea, PAH concentrations in Barents Sea sediments are generally lower than in Beaufort Sea sediments.

Yunker, M.B.; Macdonald, R.W.; Snowdon, L.R.; Smith, J.N.

1995-12-31

82

Atmospheric carbon diooxide mixing ratios from the NOAA Climate Monitoring and Diagnostics Laboratory cooperative flask sampling network, 1967-1993  

SciTech Connect

This data report documents monthly atmospheric CO{sub 2} mixing ratios and measurements obtained by analyzing individual flask air samples for the NOAA/CMDL global cooperative flask sampling network. Measurements include land-based sampling sites and shipboard measurements covering 14 latitude bands in the Pacific Ocean and South China Sea. Analysis of the NOAA/CMDL flask CO{sub 2} database shows a long-term increase in atmospheric CO{sub 2} mixing ratios since the late 1960s. This report describes how the samples are collected and analyzed and how the data are processed, defines limitations, and restrictions of the data, describes the contents and format of the data files, and provides tabular listings of the monthly carbon dioxide records.

Conway, T.J.; Tans, P.P. [National Oceanic and Atmospheric Administration, Boulder, CO (United States); BBoden, T.A. [Oak Ridge National Lab., TN (United States)

1996-02-01

83

The infrared spectra of very large, compact, highly symmetric, polycyclic aromatic hydrocarbons (PAHs)  

E-print Network

The mid-infrared spectra of large PAHs ranging from C54H18 to C130H28 are determined computationally using Density Functional Theory. Trends in the band positions and intensities as a function of PAH size, charge and geometry are discussed. Regarding the 3.3, 6.3 and 11.2 micron bands similar conclusions hold as with small PAHs. This does not hold for the other features. The larger PAH cations and anions produce bands at 7.8 micron and, as PAH sizes increases, a band near 8.5 micron becomes prominent and shifts slightly to the red. In addition, the average anion peak falls slightly to the red of the average cation peak. The similarity in behavior of the 7.8 and 8.6 micron bands with the astronomical observations suggests that they arise from large, cationic and anionic PAHs, with the specific peak position and profile reflecting the PAH cation to anion concentration ratio and relative intensities of PAH size. Hence, the broad astronomical 7.7 micron band is produced by a mixture of small and large PAH cations and anions, with small and large PAHs contributing more to the 7.6 and 7.8 micron component respectively. For the CH out-of-plane vibrations, the duo hydrogens couple with the solo vibrations and produce bands that fall at wavelengths slightly different than their counterparts in smaller PAHs. As a consequence, previously deduced PAH structures are altered in favor of more compact and symmetric forms. In addition, the overlap between the duo and trio bands may reproduce the blue-shaded 12.8 micron profile.

Charles W. Bauschlicher, Jr.; Els Peeters; Louis J. Allamandola

2008-02-07

84

PAH lines at high redshift as galaxy evolution marker  

NASA Astrophysics Data System (ADS)

Based in chemodynamical models for galaxy evolution, we studied the formation of PAH lines at high redshifts. The model considers carbon and silicon grains, and also PAH molecules. It distinguishes diffuse ISM the molecular clouds associated to star forming regions. The PAH lines provide a good signature of the evolutionary stage of galaxies, star formation rate, in addition to allowing the assessment the relative importance for of AGN and stellar emission on the output of the galaxy. In particular, the line ratio 11.3/7.7 ? m is a good marker of the age of high redshift galaxies. We expected that our calculations provide some benchmarks both for future observations both with ground and satellite instruments. The ages derived in this way for high redshift objects could be used to test dark energy models. In addition to the cosmological applications, the observations of the PAH features could be used to check the charge state of PAHs. Apparently, anions and neutrals are favored over cations.

Santos, J. H. B.; Friaça, A. C. S.

2014-10-01

85

Density diagnostic of a uranium laser-produced plasma from the line ratio of Delta n = 1 transitions in Ni-like uranium  

NASA Astrophysics Data System (ADS)

The intensity ratio of the electric quadrupole 3p(6)3d(10) - 3p(5)3/2(4)f(7/2) (J=2) line to the electric dipole 3p(6)3d(10) - 3p(5)1/2(4)s line is used as a density diagnostic of a highly ionized uranium laser-produced plasma for electron densities of 10 exp 19 - 10 exp 23/cu cm. Calculations show that this ratio is insensitive to the plasma temperature in the range of 1000-4000 eV. Self-absorption of the lines is shown to be unimportant in this density range. Experimental line ratios are compared to the predictions of a Ni-like uranium-ion model that includes 138 excited levels. The densities inferred from this analysis applied to a measured line ratio yield densities of (4.0 +/- 0.5) x 10 exp 22/cu cm. This is in good agreement with models of X-ray production in laser-produced plasmas.

Mandelbaum, P.; Seely, J. F.; Feldman, U.; Brown, C. M.; Kania, D. R.; Goldstein, W. H.; Kauffman, R. L.; Langer, S.; Bar-Shalom, A.

1992-05-01

86

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. PMID:24235972

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

2013-01-01

87

Recent Progress in DIB Research: Survey of PAHS and DIBS  

NASA Technical Reports Server (NTRS)

The spectra of several neutral and ionized PAHs isolated in the gas phase at low temperature have been measured in the laboratory under experimental conditions that mimic interstellar conditions and are compared with an extensive set of astronomical spectra of reddened, early type stars [1, 2]. The comparisons of astronomical and laboratory data provide upper limits for the abundances of specific neutral PAH molecules and ions along specific lines-of-sight. Something that is not attainable from infrared observations alone. We present the characteristics of the laboratory facility (COSmIC) that was developed for this study and discuss the findings resulting from the comparison of these unique laboratory data with high resolution, high S/N ratio astronomical observations. COSmIC combines a supersonic free jet expansion with discharge plasma and high-sensitivity cavity ringdown spectroscopy and provides experimental conditions that closely mimic the interstellar conditions. The column densities of the individual neutral PAH molecules and ions probed in these surveys are derived from the comparison of these unique laboratory data with high resolution, high S/N ratio astronomical observations. The comparisons of astronomical and laboratory data lead to clear and unambiguous conclusions regarding the expected abundances for PAHs of various sizes and charge states in the interstellar environments probed in the surveys. Band profile comparisons between laboratory and astronomical spectra lead to information regarding the molecular structures and characteristics associated with the DIB carriers in the corresponding lines-of-sight. These quantitative surveys of neutral and ionized PAHs in the optical range open the way for unambiguous quantitative searches of PAHs and complex organics in a variety of interstellar and circumstellar environments.

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

2013-01-01

88

Biological PAH degradation in dredged sludges  

SciTech Connect

Sediment-associated PAHs are biodegraded by fungi under low pH conditions. The 16 polycyclic aromatic hydrocarbons (PAHs) targeted by the US Environmental Protection Agency (US EPA) are converted by more than 95% within a period of 20 weeks. The process appears to be a metabolic conversion, because PAH removal occurred in absence of additional growth substrates.

Huis in`t Veld, M.G.A.; Werners, J.; Doddema, H.J. [TNO Inst. of Environmental Sciences, Delft (Netherlands); Veen, J.J. van [TNO Inst. of Environmental and Energy Technology, Apeldoorn (Netherlands)

1995-12-31

89

The 15-21 um PAH plateau  

E-print Network

We present 14--21 um emission spectra of star forming regions and compare them with the PAH spectra from the Ames PAH database. We show that while the emission in this region can be quite variable, the bulk of these variations can be accommodated by variations in the IS PAH population.

E. Peeters; A. L. Mattioda; F. Kemper; D. M. Hudgins; L. J. Allamandola

2005-06-30

90

IMMUNOCHEMICAL DETECTION OF POLYCYCLIC AROMATIC HYDROCARBONS (PAHs)  

Microsoft Academic Search

This review gives a short introduction in the origin, occurrence and detection of polycyclic aromatic hydrocarbons (PAHs). Emphasis lies on immunochemical detection methods for PAH compounds, such as ELISA, RIA, fluoroimmunosensors, QCM immunosensors and electrochemical immunosensors, but also on immunosorbents and commercial immunoassay kits for PAHs. Possibilities and limitations of these methods compared to standard methods, such as HPLC and

Karsten A. Fähnrich; Miloslav Pravda; George G. Guilbault

2002-01-01

91

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

92

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

93

Hybrid time dependent/independent solution for the He I line ratio temperature and density diagnostic for a thermal helium beam with applications in the scrape-off layer-edge regions in tokamaks  

SciTech Connect

Spectroscopic studies of line emission intensities and ratios offer an attractive option in the development of non-invasive plasma diagnostics. Evaluating ratios of selected He I line emission profiles from the singlet and triplet neutral helium spin systems allows for simultaneous measurement of electron density (n{sub e}) and temperature (T{sub e}) profiles. Typically, this powerful diagnostic tool is limited by the relatively long relaxation times of the {sup 3}S metastable term of helium that populates the triplet spin system, and on which electron temperature sensitive lines are based. By developing a time dependent analytical solution, we model the time evolution of the two spin systems. We present a hybrid time dependent/independent line ratio solution that improves the range of application of this diagnostic technique in the scrape-off layer (SOL) and edge plasma regions when comparing it against the current equilibrium line ratio helium model used at TEXTOR.

Munoz Burgos, J. M. [Oak Ridge Institute for Science Education, Oak Ridge, Tennessee 37830 (United States); Schmitz, O. [Institute fuer Energieforschung-Plasmaphysik, Forschungszentrum Juelich, Association EURATOM-FZJ, Trilateral Euregio Cluster, D-52425 Juelich (Germany); Loch, S. D.; Ballance, C. P. [Physics Department, Auburn University, Auburn, Alabama 36849 (United States)

2012-01-15

94

Removal of polycyclic aromatic hydrocarbons (PAHs) from industrial sludges in the ambient air conditions: automotive industry.  

PubMed

Removal of polycyclic aromatic hydrocarbons (PAHs) existed in automotive industry treatment sludge was examined by considering the effects of temperature, UV, titanium dioxide (TiO2) and diethyl amine (DEA) in different dosages (i.e., 5% and 20%) in this study. Application of TiO2 and DEA to the sludge samples in ambient environment was studied. Ten PAH (?10 PAH) compounds were targeted and their average value in the sludge was found to be 4480 ± 1450 ng/g dry matter (DM). Total PAH content of the sludge was reduced by 25% in the ambient air environment. Meteorological conditions, atmospheric deposition, evaporation and sunlight irradiation played an effective role in the variations in PAH levels during the tests carried out in ambient air environment. Moreover, it was observed that when the ring numbers of PAHs increased, their removal rates also increased. Total PAH level did not change with the addition of 5% DEA and only 10% decreased with 5% TiO2 addition. PAH removal ratios were 8% and 32% when DEA (20%) and TiO2 (20%) were added, respectively. It was concluded that DEA was a weak photo-sensitizer yet TiO2 was effective only at 20% dosage. PMID:23485234

Karaca, Gizem; Tasdemir, Yucel

2013-01-01

95

Source apportionment of PAHs using Unmix model for Yantai costal surface sediments, China.  

PubMed

16 Polycyclic aromatic hydrocarbons (PAHs) in 20 surface sediments from Yantai offshore area were measured. The total PAHs concentrations varied from 450.0 to 4,299.0 ng/g, with a mean of 2,492.9 ng/g. The high molecular weight (HMW) PAHs were most abundant and the ratio ranged from 54.9 % to 81.6 % in all sampling stations, indicating that pyrogenic sources were a predominant contribution to PAHs pollution. The source contributions of PAHs were estimated based on the EPA Unmix 6.0 receptor model. The data were well simulated due to a high correlation coefficient between predicted and measured PAHs concentration (R(2) = 0.99). A mixed source of coal combustion and traffic pollution contributed to 38.9 % of the measured PAHs, followed by diesel emission (38.8 %) and a mixed source of biomass combustion and gasoline engine emissions (22.3 %). The current findings further validated that Unmix model could be applied to apportion the sources of PAHs in sediments. PMID:24292847

Lang, Yin-Hai; Yang, Wei

2014-01-01

96

Polycyclic aromatic hydrocarbons (PAHs) in the mariculture zones of China's northern Yellow Sea.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) were detected in water and sediment samples collected from three mariculture zones in China's northern Yellow Sea. In these samples, total PAH concentrations ranged from 110.8 ng/L to 997.2 ng/L and 142.2 ng/gdry weight (dw) to 750.2 ng/gdw, respectively. The log KOC values of the various PAH compounds examined in this study increased with the log KOW values, which is consistent with the prediction regarding PAH behavior in the environment. However, these KOC values were lower than the predicted values as a result of the effects of organic matters, which were abundant in the mariculture water. The isomeric ratios of the PAHs in sediment indicated that the source of the PAHs in the mariculture zones were mainly pyrolytic. The TEQ(carc) values of PAHs ranged from 7 ng TEQ/gdw to 92 ng TEQ/gdw, and only a few samples met the safe criterion with respect to individual PAH concentrations. PMID:24952456

Zong, Humin; Ma, Xindong; Na, Guangshui; Huo, Chuanlin; Yuan, Xiutang; Zhang, Zhifeng

2014-08-15

97

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. PMID:18515848

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

2008-01-01

98

Fullerenes and PAHs in space.  

NASA Astrophysics Data System (ADS)

Theoretical, observational and laboratory work on the new form of carbon known as fullerenes and its hydrogenated forms (fulleranes) are reviewed. These molecules can be responsible of diffuse interstellar bands, the UV bump, a major feature in the extinction curves measured in many lines of sight in our Galaxy and other galaxies and the anomalous microwave emission detected in several regions of star formation,in molecular clouds and HII regions. Recent detections of fullerenes C60 and C70 in planetary nebulae of our Galaxy and in the Magallanic cloud render support to the hypothesis that fullerenes and fulleranes are carriers of these processes. Other potential agents of these emission and absorption processes are the polycyclic aromatic hydrocarbons (PAHs). We also review observational efforts to identify the most simple PAHs, naphthalene and anthracene, in regions of anomalous microwave emission.

Iglesias-Groth, S.

99

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 753 ng/g d.w., with a mean of 118±132 ng/g. The highest concentrations was found in the mid-southern part of the YRD (753 ng/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

100

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

101

A wintertime study of PAHs in fine and coarse aerosols in São Paulo city, Brazil  

Microsoft Academic Search

The Polycyclic aromatic hydrocarbons PAHs (naphthalene, acenaphthylene, acenaphthene, phenanthrene, fluoranthene, pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene and benzo(ghi)perylene) concentrations in fine (PM2.5) and coarse (PM2.5–10) atmospheric particulate matter were measured at São Paulo city, Brazil. The dominant PAH compounds were indeno(1,2,3-cd)pyrene, benzo(ghi)perylene and benzo(b)fluoranthene for both the fractions. The calculated ratios of some specific PAHs were in close agreement

Christine Bourotte; Maria-Cristina Forti; Satie Taniguchi; Marcia Caruso Bícego; Paulo Andrade Lotufo

2005-01-01

102

Carcinogenic PAH in waterpipe charcoal products  

PubMed Central

Because narghile waterpipe (shisha, hooka) smoking normally involves the use of burning charcoal, smoke inhaled by the user contains constituents originating from the charcoal in addition to those from the tobacco. We have previously found that charcoal accounts for most of the polyaromatic hydrocarbons (PAH) and carbon monoxide in the smoke of the waterpipe, both of which are present in alarming quantities. Because charcoal manufacturing conditions favor formation of PAH, it is reasonable to assume that charcoal sold off the shelf may be contaminated by PAH residues. These residues may constitute a significant fraction of the PAH inhaled by the waterpipe user and those in her/his vicinity. We measured PAH residues on three kinds of raw waterpipe charcoal sampled from Beirut stores and cafés. We found that PAH residues in raw charcoal can account for more than half of the total PAH emitted in the mainstream and sidestream smoke, and about one sixth of the carcinogenic 5- and 6-ring PAH compounds. Total PAH content of the three charcoal types varied systematically by a factor of six from the charcoal with the least to the greatest PAH residue. These findings indicate the possibility of regulating charcoal carcinogen content. PMID:20807559

Sepetdjian, Elizabeth; Saliba, Najat; Shihadeh, Alan

2010-01-01

103

Fate of polycyclic aromatic hydrocarbon (PAH) contamination in a mangrove swamp in Hong Kong following an oil spill.  

PubMed

The fate of polycyclic aromatic hydrocarbon (PAH) contamination in a mangrove swamp (Yi O) in Hong Kong after an oil spill accident was investigated. The concentrations and profiles of PAHs in surface sediments collected from five quadrats (each of 10 m x 10 m) covering different degrees of oil contamination and the most contaminated mangrove leaves were examined in December 2000 (30 days after the accident) and March 2001 (126 days later). The concentrations of total PAHs in surface sediments ranged from 138 to 2,135 ng g(-1), and PAHs concentrations decreased with time. In the most contaminated sediments, total PAHs dropped from 2,135 (30 days) to 1,196 ng g(-1) (120 days), and the decrease was smaller in less contaminated sediments. The percentage reduction in sediment PAHs over three months (44%) was less significant than that in contaminated leaves (85%), indicating PAH in or on leaves disappeared more rapidly. The PAH profiles were very similar in sediments collected from quadrats Q1 and Q2 with benzo[a]anthracene and pyrene being the most abundant PAH compounds, but were different in the other three quadrats. The proportion of the light molecular weight PAHs to total PAHs increased after three months, especially phenanthrene. Results suggest that physical and photo-chemical weathering (tidal washing and photo-oxidation) of crude oil in surface sediments and on plant leaves were important processes in the first few months after the oil spill. The PAH contamination in Yi O swamp came from both petrogenic and pyrolytic sources. The petrogenic characteristic in the most contaminated sediment was confirmed with high values of phenanthrene to anthracene ratio (>10) and low values of fluoranthene to pyrene ratio (0.3-0.4). PMID:12398405

Ke, L; Wong, Teresa W Y; Wong, Y S; Tam, Nora F Y

2002-01-01

104

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. PMID:19943816

Bouzas, Lorena; Hermida, Jesus

2010-01-01

105

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

106

PAHs And Parking Lots: A Field Study on PAHs Exported From Sealed and Unsealed Parking  

E-print Network

-based (asphalt resin, ball clay, silica) · Coal tar-based (coal tar, ball clay) Coal tar - High PAHs - 50,000 mg Hydrocarbons (PAHs) Class of hydrocarbon compounds created by incomplete combustion of organic material Some

107

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

108

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

109

Particle-Bound PAH Emission from the Exhaust of Combustion Chamber  

NASA Astrophysics Data System (ADS)

Polycyclic Aromatic Hydrocarbons (PAHs) are harmful, semi-volatile organic compounds which are generated due to the incomplete combustion of organic substances. PAHs are of concern as a pollutant because some of these compounds are carcinogenic and mutagenic even at low levels. Most of the PAHs are recalcitrant and persistent in the environment. The PAHs carcinogenic potential can be increased by the adsorption onto small size particles (< 1?m) which can easily get into the bronchioles and alveoli of the lungs. PAHs associated with sub-micron particles are mostly generated from high temperature sources like combustion chambers. In this current study, the presence of 16 priority PAHs (listed by United States Environmental Protection Agency) which are attached to the particulates emitted from the exhaust of the jet engine are evaluated. The engine was operated at different swirl numbers (S; the ratio of tangential air flow to axial air flow) to investigate the effect of this parameter on the effluent of combustion chamber. The samples were collected using two instruments simultaneously: a particle analyzer and a Micro-Orifice Uniform Deposited Impactor (MOUDI). Particle analyzer was used to count the number of particles in different sizes and MOUDI was used to collect particles with respect to their size as they were emitted from the exhaust. The MOUDI's aluminum substrates were weighed before and after the experiment in order to measure the mass of particles that were collected during the sampling period. The concentration of PAHs associated with the particles was measured by extracting the particles with dichloromethane followed by analysis via gas chromatography/mass spectrometry (GC/MS). In general, lower molecular weight PAHs emitted from the exhaust of combustion chamber are mostly in gas phase while PAHs of higher molecular weight are adsorbed onto particles. Preliminary results from GC/MS confirm the presence of higher molecular weight PAHs like Benzo[a]pyrene in most of the samples. Better recirculation between air and fuel in higher swirl numbers results in better combustion. In higher swirl numbers, the temperature of the combustion process increases which leads to a more complete combustion. Another result of higher swirl number is a longer residence time which allows the organic substances in the fuel to remain in the reaction longer and also leads to a more complete combustion. The preliminary results from particle analyzer show that the abundance ratio of smaller particles to larger particles increases at higher swirl numbers. For example, at swirl 86, the abundance ratio of 0.3 micron particles to 0.7 micron particles was 400 while at swirl 0, this ratio was 35. Smaller particles have higher specific surface area which allows for more PAH adsorption. The preliminary results show that operating the jet engine at higher swirl numbers can have positive or negative effects on particle-bound PAH emissions. Higher temperature and residence time as well as better mixture of fuel and air can reduce PAH emission while generating more small size particles can increase surface available for PAH adsorption and, as a result, increases PAH emission. In future experiments, particle-bound PAHs of different swirl numbers will be compared in order to find a swirl number range which generates fewer Particle-bound PAHs.

Asgari Lamjiri, M.; Medrano, Y. S.; Guillaume, D. W.; Khachikian, C. S.

2013-12-01

110

Chemical-assisted phytoremediation of CD-PAHs contaminated soils using Solanum nigrum L.  

PubMed

A well-characterized cadmium (Cd) hyperaccumulating plant Solanum nigrum was grown in Cd and polycyclic aromatic hydrocarbons (PAHs) co-contaminated soil that was repeatedly amended with chemicals, including EDTA, cysteine (CY), salicylic acid (Sa), and Tween 80 (TW80), to test individual and combined treatment effects on phytoremediation of Cd-PAHs contaminated soils. Plant growth was negatively affected by exogenous chemicals except for EDTA. S. nigrum could accumulate Cd in tissues without assistant chemicals, while there was no visible effect on the degradation of PAHs. Cysteine had significant effects on phytoextraction of Cd and the highest metal extraction ratio (1.27%) was observed in 0.9 mmol/kg CY treatment. Both salicylic acid and Tween 80 had stimulative effects on the degradation of PAHs and there was the maximal degradation rate (52.6%) of total PAHs while 0.9 mmol/kg Sa was applied. Furthermore, the combined treatment T(0.1EDTA+0.9CY+0.5TW80) and T(0.5EDTA+0.9CY+03Sa) could not only increase the accumulation of Cd in plant tissues, but also promote the degradation of PAHs. These results indicated that S. nigrum might be effective in phytoextracting Cd and enhancing the biodegradation of PAHs in the co-contaminated soils with assistant chemicals. PMID:21972521

Yang, Chuanjie; Zhou, Qixing; Wei, Shuhe; Hu, Yahu; Bao, Yanyu

2011-09-01

111

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

112

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

113

A Survey of 3.3 Micron PAH Emission in Planetary Nebulae  

E-print Network

Results are presented from a pilot survey of 3.3 micron PAH emission from planetary nebulae using FLITECAM, an instrument intended for airborne astronomy with SOFIA. The observations were made during ground-based commissioning of FLITECAM's spectroscopic mode at the 3-m Shane telescope at Lick Observatory. Direct-ruled KRS-5 grisms were used to give a resolving power (R)~1,700. Targets were selected from IRAS, KAO and ISO sources with previously observed PAH emission at longer wavelengths. AGB stars and PN with C/O ratios < 1 were also added to the target list in order to test PAH detection thresholds. In all, 20 objects were observed. PAH emission was detected in 11 out of 20 observed targets.

Erin C. D. Smith; Ian S. McLean

2007-12-05

114

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.

115

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...

116

Optical and infrared emission of H II complexes as a clue to the PAH life cycle  

NASA Astrophysics Data System (ADS)

We present an analysis of optical spectroscopy and infrared aperture photometry of more than 100 H II complexes in nine galaxies. Spectra obtained with the 6-m telescope of Special Astrophysical Observatory of the Russian Academy of Sciences are used along with archival data from Spitzer and several ground-based telescopes to infer a strength of polycyclic aromatic hydrocarbon (PAH) emission, age, properties of the UV radiation field, and metallicity of studied H II complexes. Physical properties (age, radiation field parameters, metallicity) are related to the F8/F24 ratio used as a proxy for the PAH abundance in order to reveal factors that may influence the PAH evolution in H II complexes. The well-known correlation between the F8/F24 ratio and metallicity is confirmed in the studied complexes. The infrared flux ratio also correlates with the [O III]?5007/H? ratio which is often considered as an indicator of the radiation field hardness, but this correlation seems to be a mere reflection of a correlation between [O III]?5007/H? and metallicity. In separate metallicity bins, the F8/F24 ratio is found to correlate with an age of an H II complex, which is estimated from the equivalent width of H? line. The correlation is positive for low-metallicity complexes and negative for high-metallicity complexes. Analysing various mechanisms of PAH formation and destruction in the context of found correlations, we suggest that PAH abundance is likely altered by the UV radiation within H II complexes, but this is not necessarily due to their destruction. If PAHs can also form in H II complexes due to some processes like aromatization, photodestruction, shattering and sputtering of very small grains, the net F8/F24 ratio is determined by a balance between all these processes that can be different at different metallicities.

Khramtsova, M. S.; Wiebe, D. S.; Lozinskaya, T. A.; Egorov, O. V.

2014-10-01

117

Determining air-water exchange, spatial and temporal trends of freely dissolved PAHs in an urban estuary using passive polyethylene samplers.  

PubMed

Passive polyethylene (PE) samplers were deployed at six locations within Narragansett Bay (RI, USA) to determine sources and trends of freely dissolved and gas-phase polycyclic aromatic hydrocarbons (PAHs) from May to November 2006. Freely dissolved aqueous concentrations of PAHs were dominated by fluoranthene, pyrene, and phenanthrene, at concentrations ranging from tens to thousands of pg/L. These were also the dominant PAHs in the gas phase, at hundreds to thousands of pg/m3. All stations mostly followed the same temporal trends, with highest concentrations (up to 7300 pg/L for sum PAHs) during the second of 11 deployments, coinciding with a major rainstorm. Strong correlations of sum PAHs with river flows and wastewater treatment plant discharges highlighted the importance of rainfall in mobilizing PAHs from a combination of runoff and atmospheric washout. PAH concentrations declined through consecutive deployments III to V, which could be explained by an exponential decay due to flushing with cleaner ocean water during tides. The estimated residence time (tres) of the PAH pulse was 24 days, close to an earlier estimate of tres of 26 days for freshwater in the Bay. Air-water exchange gradients indicated net volatilization of most PAHs closest to Providence. Further south in the Bay, gradients had changed to mostly net uptake of the more volatile PAHs, but net volatilization for the less volatile PAHs. Based on characteristic PAH ratios, freely dissolved PAHs at most sites originated from the combustion of fossil fuels; only two sites were at times affected by fuel spill-derived PAHs. PMID:21351793

Lohmann, Rainer; Dapsis, Meredith; Morgan, Eric J; Dekany, Victoria; Luey, Pamela J

2011-04-01

118

Observing PAH Hydrogenation with Scanning Tunneling Microscopy  

NASA Astrophysics Data System (ADS)

The interaction between thin films of polycyclic aromatic hydrocarbons (PAHs) and atomic H has been studied using scanning tunneling microscopy (STM). Observational evidence suggests that hydrogenated PAHs are located in regions of the interstellar medium (ISM) where there are high concentrations of molecular hydrogen (H2)1. It has previously been postulated that hydrogenated PAHs act as catalysts for the formation of H22. While many studies have focused on the role of ionic PAHs in the formation of H23, here we consider the role of neutral species. Neutral PAHs are expected to be stable and to condense on grain surfaces present in dense interstellar clouds, in regions of low UV flux4. PAH molecules were deposited in thin films under ultra high vacuum (UHV) conditions. Monolayer films were subsequently characterised using STM, at liquid N2 temperatures. The films were then exposed to thermally-cracked atomic H and were again characterised using STM. Contrast in the STM images showed submolecular changes to the electronic structure of the PAH molecules only after exposure to atomic H. This suggests the formation of superhydrogenated species. DFT calculations have predicted that such superhydrogenated species are stable and can act as catalysts for the formation of H2 through abstraction reactions5. Complimentary thermal desorption experiments support these findings.

Cassidy, A. M.; Nilsson, L.; Balog, R.; Thrower, J.; Jorgensen, B.; Hornekaer, L.

2011-05-01

119

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

120

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.

2014-04-01

121

Occurrence, Distribution, Environmental Risk Assessment and Source Apportionment of Polycyclic Aromatic Hydrocarbons (PAHs) in Water and Sediments of the Liaohe River Basin, China.  

PubMed

The occurrence and distribution of polycyclic aromatic hydrocarbons (PAHs) were investigated in water and sediments in Liaohe River Basin. The total PAH concentrations ranged from 111.9 to 2,931.6 ng/L in water and from 92.2 to 295,635.2 ng/g dry weight (dw) in sediments. The PAHs in water were dominated by 2-, 3- and 4-ring PAHs, which accounted for 42.8 %, 39.4 % and 14.2 % of the total PAHs, respectively, while in sediment PAHs were dominated by 3-, 4- and 5-ring PAHs, which accounted for 26.5 %, 44.2 % and 17.4 % of the total PAHs, respectively. The benzo[a]pyrene equivalents for water samples showed that in 37 out of 50 sites the values were greater than the national standard, and the environmental risk assessment indicated that high environmental risk of PAHs existed in sediments. Using the molecular ratio method for the source identification it was concluded that PAHs were determined to be from mixed sources (petroleum and combustion) in Liaohe River system and combustion sources in Daliao River system. PMID:25323038

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

2014-12-01

122

Amphibian responses to photoinduced toxicity of PAHs  

SciTech Connect

Amphibians are essential components of many ecosystems, yet little information exists on their sensitivity to environmental stressors. Recent evidence shows amphibian diversity is declining. Others have suggested this decline is a result of increasing ultraviolet (UV) light levels. Polycyclic aromatic hydrocarbons (PAHs) are widespread pollutants in the aquatic environment and their toxicity is increased in the presence of UV light. Embryos of two frogs (Rana pipiens and Xenopus laevis) were exposed to a PAH, fluoranthene, to evaluate amphibian responses to this common contaminant in the presence of sunlight. Hatching rate and development were measured in field and laboratory exposures at multiple concentrations and varying UV intensities. Hatching rate was relatively unaffected, while newly hatched larvae were sensitive to low (ug/L) concentrations. Response was related to both PAH concentration and UV intensity. Results suggest that PAH contamination in the aquatic environment may contribute to declines in amphibian populations.

Hatch, A.C.; Burton, G.A. Jr. [Wright State Univ., Dayton, OH (United States). Biological Sciences Dept.

1995-12-31

123

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

124

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 (...

125

Isolation of Adherent Polycyclic Aromatic Hydrocarbon (PAH)-Degrading Bacteria Using PAH-Sorbing Carriers  

PubMed Central

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 Mycobacterium 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. PMID:10788347

Bastiaens, Leen; Springael, Dirk; Wattiau, Pierre; Harms, Hauke; deWachter, Rupert; Verachtert, Hubert; Diels, Ludo

2000-01-01

126

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

127

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

128

Developing strategies for PAH and TCE bioremediation  

SciTech Connect

Bioremediation is the controlled use of microbes, commonly bacteria and fungi, to reclaim soil and water contaminated with substances that are deleterious to human health and the environment. The organisms used often naturally inhabit the polluted matrix; however, they may inhabit a different environment and be used as seed organisms because of their ability to degrade a specific class of substances. It is because of the wide diversity of microbial metabolic potential that bioremediation is possible. Polyaromatic hydrocarbons (PAHs) are organic compounds that are ubiquitous in the environment. They are present in fossil fuels and are formed during the incomplete combustion of organic material. PAHs exhibit low volatility and low aqueous solubility. As the molecular weight of these compounds increases, there is an exponential decrease in solubility and volatility. PAHs tend to adsorb onto soils and sediments because of their hydrophobic character, which is an intrinsic function of molecular size. The microbial degradation of individual PAHs by pure cultures and mixed populations occurs under a wide range of soil types and environmental conditions. Generally, the factors having the greatest influence on PAH biodegradation rates are soil moisture content, pH, inorganic nutrients present, PAH loading rates, initial PAH concentrations, and the presence of an acclimated microbial population. Feasibility studies are essential for developing a bioremediation strategy and are performed in a phased testing program that is designed to accomplish a number of objectives. These objectives include establishing an indigenous microbial population that will degrade specific contaminants, defining the rate-limiting factors for enhanced PAH degradation and the optimal treatment in terms of rates and cleanup levels attainable, and developing design parameters for field operations.

Mahaffey, W.R.; Nelson, M.; Kinsella, J. (Ecova Corp., Redmond, WA (United States)); Compeau, G. (Applied Geosciences, Inc., Bellevue, WA (United States))

1991-10-01

129

Properties of Polycyclic Aromatic Hydrocarbons in the Northwest Photon Dominated Region of NGC 7023. II. Traditional PAH Analysis Using k-means as a Visualization Tool  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbon (PAH) emission in the Spitzer-IRS spectral map of the northwest photon dominated region (PDR) in NGC 7023 is analyzed using the "traditional" approach in which the PAH bands and plateaus between 5.2-19.5 ?m are isolated by subtracting the underlying continuum and removing H2 emission lines. The spectra are organized into seven spectroscopic bins by using k-means clustering. Each cluster corresponds to, and reveals, a morphological zone within NGC 7023. The zones self-organize parallel to the well-defined PDR front that coincides with an increase in intensity of the H2 emission lines. PAH band profiles and integrated strengths are measured, classified, and mapped. The morphological zones revealed by the k-means clustering provides deeper insight into the conditions that drive variations in band strength ratios and evolution of the PAH population that otherwise would be lost. For example, certain band-band relations are bifurcated, revealing two limiting cases; one associated with the PDR, the other with the diffuse medium. Traditionally, PAH band strength ratios are used to gain insight into the properties of the emitting PAH population, i.e., charge, size, structure, and composition. Insights inferred from this work are compared and contrasted to those from Boersma et al. (first paper in this series), where the PAH emission in NGC 7023 is decomposed exclusively using the PAH spectra and tools made available through the NASA Ames PAH IR Spectroscopic Database.

Boersma, C.; Bregman, J.; Allamandola, L. J.

2014-11-01

130

Evolution of PAHs in protoplanetary disks  

E-print Network

Depending on whom you ask, PAHs are either the smallest dust particles or the largest gas-phase molecules in space. Whether referred to as gas or dust, these PAHs can contain up to 20% of the total cosmic carbon abundance and as such also play an important role in the carbon chemistry of protoplanetary disks. The interpretation of PAH bands is often a complex procedure involving not only gas physics to determine their ionization stage and temperature, but also radiative transfer effects that can bury these bands in a strong thermal continuum from a population of larger dust particles. PAHs are most readily seen in the spectral energy distributions (SEDs) of disks around Herbig AeBe stars where they are photoprocessed by the stellar radiation field. Resolved images taken in the PAH bands confirm their origin in the flaring surfaces of circumstellar disks: if the SED is consistent with a flat disk structure (less illuminated), there is little or no evidence of PAH emission. The very low detection rates in the d...

Kamp, Inga

2011-01-01

131

Decision Making for Borderline Cases in Pass/Fail Clinical Anatomy Courses: The Practical Value of the Standard Error of Measurement and Likelihood Ratio in a Diagnostic Test  

ERIC Educational Resources Information Center

Several studies have shown that the standard error of measurement (SEM) can be used as an additional “safety net” to reduce the frequency of false-positive or false-negative student grading classifications. Practical examinations in clinical anatomy are often used as diagnostic tests to admit students to course final examinations. The aim of this…

Severo, Milton; Silva-Pereira, Fernanda; Ferreira, Maria Amelia

2013-01-01

132

PAHs And Parking Lots: A Field Study on PAHs Exported From Sealed and Unsealed Parking  

E-print Network

common types · Asphalt-based (asphalt resin, ball clay, silica) · Coal tar-based (coal tar, ball clay #12;Why do we care? Coal tar - High PAHs (polycyclic aromatic hydrocarbons) Asphalt sealant 50 mg in Austin, TX 1,400,000 gallons annually NY/NJ watershed #12;Polycyclic Aromatic Hydrocarbons (PAHs) EPA

133

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

134

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. PMID:21247097

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

135

On the driving force of PAH production  

NASA Technical Reports Server (NTRS)

The kinetic factors affecting the production of polycyclic aromatic hydrocarbons (PAH) in high-temperature pyrolysis and combustion environments are analyzed. A lumped kinetic model representing polymerization-type growth by one irreversible step and two reversible steps is considered. It is shown that at high temperatures, PAH growth is controlled by the superequilibrium of hydrogen atoms; at low temperatures and low H2 concentrations, the PAH growth rate is proportional to the rate of the H-abstraction of a hydrogen atom from aromatic molecules; while at low temperatures and high H2 concentrations, it is controlled by the thermodynamics of the H-abstraction and the kinetics of acetylene addition to aromatic radicals. The presence of oxygen mainly affects the small-molecule reactions during the induction period.

Frenklach, Michael

1989-01-01

136

Evaluation of PAH contamination in soil treated with solid by-products from shale pyrolysis.  

PubMed

The aim of this work was to evaluate the concentrations of polycyclic aromatic hydrocarbons (PAHs) in soils to which solid shale materials (SSMs) were added as soil conditioners. The SSMs were derived from the Petrosix® pyrolysis process developed by Petrobras (Brazil). An improved ultrasonic agitation method was used to extract the PAHs from the solid samples (soils amended with SSMs), and the concentrations of the compounds were determined by gas chromatography coupled to mass spectrometry (GC-MS). The procedure provided satisfactory recoveries, detection limits, and quantification limits. The two-, three-, and four-ring PAHs were most prevalent, and the highest concentration was obtained for phenanthrene (978?±?19 ?g kg(-1) in a pyrolyzed shale sample). The use of phenanthrene/anthracene and fluoranthene/pyrene ratios revealed that the PAHs were derived from petrogenic rather than pyrogenic sources. The measured PAH concentrations did not exceed national or international limit values, suggesting that the use of SSMs as soil conditioners should not cause environmental damage. PMID:25399121

Nicolini, Jaqueline; Khan, Muhammad Y; Matsui, M; Côcco, Lílian C; Yamamoto, Carlos I; Lopes, Wilson A; de Andrade, Jailson B; Pillon, Clenio N; Arizaga, Gregorio G Carbajal; Mangrich, Antonio S

2015-01-01

137

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

138

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...

139

Effect of sorption and substrate pattern on PAH degradability  

SciTech Connect

The effect of sorption and the substrate pattern on the degradability of polycyclic aromatic hydrocarbons (PAHs) during bioremediation of PAH-contaminated silt in a slurry reactor was investigated. Biological degradation of high-molecular-weight PAH compounds sorbed to silt and clay particles was enhanced in the presence of low-molecular-weight PAHs. In soil suspensions containing silt contaminated with PAH compounds of different molecular weights, PAHs containing four aromatic rings were degraded more readily in the presence of naphthalene. Bioavailability of PAHs was correlated to the water solubility of different compounds; a significant limitation of bacterial growth and activity due to sorption of PAHs to the fine particles could not be observed.

Ressler, B.P.; Kaempf, C.; Winter, J. [Univ. Karlsruehe (Germany)

1995-12-31

140

PAH characteristics in the ambient air of traffic-source  

Microsoft Academic Search

Twenty-seven PAH (polycyclic aromatic hydrocarbon) samples in the ambient air of a traffic-source were investigated for their concentration, particle-bound PAH composition, phase distribution, time variation, and distance variation. In addition, 18 and 12 PAH samples in the ambient air of an urban site and a rural site, respectively, were determined and compared with those of the traffic-source. The total-PAH concentrations

Wen-Jhy Lee; Ya-Fen Wang; Ta-Chang Lin; Ying-Yuan Chen; Weng-Chang Lin; Chin-Chuen Ku; Juei-Tang Cheng

1995-01-01

141

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. PMID:22428611

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

2012-01-01

142

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 ...

143

PAH Sorption Mechanism and Partitioning Behavior in  

E-print Network

. Introduction Prior to the widespread distribution of natural gas, manu- factured gas from coke, coal, and oil heating checker brick with air and oil and then making gas by atomizing oil with high-pressure steamPAH Sorption Mechanism and Partitioning Behavior in Lampblack-Impacted Soils from Former Oil-Gas

Zare, Richard N.

144

Sorption and chemical transformation of PAH`s on coal fly ash  

SciTech Connect

The major objective of this work was to characterize the interactions of coal fly ash with polycyclic aromatic hydrocarbons (PAHS) and their derivatives, and to attempt to understand the influence of the surface properties of coal ash (and other atmospheric particles) on the chemical transformations of polycyclic aromatic compounds. Our studies have concentrated on the photochemical behavior of PAHs sorbed form the vapor phase on coal fly ashes, and compositional subfractions obtained therefrom. The PAHs are deposited onto the fly ash substrates from the vapor phase, using apparatus and techniques developed in this laboratory in order to simulate, as closely as possible under laboratory conditions, the processes by which PAHs deposit onto fly ash particles in the atmosphere. In this report phototransformation of pyrene sorbed on fly ash fractions, and phototransformations of 1-nitropyrene sorbed on fly ash fractions are discussed.

Mamantov, G.; Wehry, E.L.

1995-05-09

145

PAHs And Parking Lots: A Field Study on PAHs Exported From Sealed and Unsealed Parking  

E-print Network

" Mahler et al., 2005. #12;4 UNH WEST EDGE LOT UNH SC RESEARCH FACILITY Watershed Boundary #12;Automated could indeed be the dominant source of PAHs to watersheds with residential and commercial development

146

Sorption of polycyclic aromatic hydrocarbons (PAHs) on glass surfaces  

Microsoft Academic Search

Sorption of polycyclic aromatic hydrocarbons (PAHs) to glass commonly used in laboratories was studied. Sorption coefficients (Kd) of five selected PAHs to borosilicate glass surfaces were measured using column chromatography. A linear relationship between log Kd and the corresponding water solubility of the subcooled liquid (logSw) of the investigated PAHs was observed. Based on the determined sorption coefficients our data

Yuan Qian; Tjorben Posch; Torsten C. Schmidt

2011-01-01

147

STUDIES ON THE MICROBIAL ECOLOGY OF PAH DEGRADATION  

EPA Science Inventory

Soils with known history of exposure to polycyclic aromatic hydrocarbons (PAHS) were collected from Norway, Germany and the United States and screened for the presence of PAH-degrading bacteria. urified PAH-degrading isolates were characterized by fatty acid profile analysis (GC-...

148

Biodegradation aspects of Polycyclic Aromatic Hydrocarbons (PAHs): A review  

Microsoft Academic Search

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

A. K. Haritash; C. P. Kaushik

2009-01-01

149

Sediment PAH Allocation Using Parent PAH Proportions and a Least Root Mean Squares Mixing Model  

Microsoft Academic Search

This article presents the case study of a forensic approach used to apportion polycyclic aromatic hydrocarbon (PAH) sediment impacts among two upland legacy contamination source areas—a former manufactured gas plant (MGP) Site and a mixed-use landfill\\/lumber mill\\/wood-treating facility—at a Great Lakes National Priorities List (NPL) site. The method uses “parent” (non-alkylated) PAH proportions to empirically define the in-situ mass signature

Kurt Herman; Eric J. Wannamaker; Gautham B. Jegadeesan

2012-01-01

150

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

151

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

152

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

153

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

154

PM, carbon, and PAH emissions from a diesel generator fuelled with soy-biodiesel blends.  

PubMed

Biodiesels have received increasing attention as alternative fuels for diesel engines and generators. This study investigates the emissions of particulate matter (PM), total carbon (TC), e.g., organic/elemental carbons, and polycyclic aromatic hydrocarbons (PAHs) from a diesel generator fuelled with soy-biodiesel blends. Among the tested diesel blends (B0, B10 (10 vol% soy-biodiesel), B20, and B50), B20 exhibited the lowest PM emission concentration despite the loads (except the 5 kW case), whereas B10 displayed lower PM emission factors when operating at 0 and 10 kW than the other fuel blends. The emission concentrations or factors of EC, OC, and TC were the lowest when B10 or B20 was used regardless of the loading. Under all tested loads, the average concentrations of total-PAHs emitted from the generator using the B10 and B20 were lower (by 38% and 28%, respectively) than those using pure petroleum diesel fuel (B0), while the emission factors of total-PAHs decreased with an increasing ratio of biodiesel to premium diesel. With an increasing loading, although the brake specific fuel consumption decreased, the energy efficiency increased despite the bio/petroleum diesel ratio. Therefore, soy-biodiesel is promising for use as an alternative fuel for diesel generators to increase energy efficiency and reduce the PM, carbon, and PAH emissions. PMID:20307928

Tsai, Jen-Hsiung; Chen, Shui-Jen; Huang, Kuo-Lin; Lin, Yuan-Chung; Lee, Wen-Jhy; Lin, Chih-Chung; Lin, Wen-Yinn

2010-07-15

155

Photodestruction of PAHs in Planetary Nebulae  

NASA Astrophysics Data System (ADS)

It is known that polycyclic aromatic hydrocarbons (PAHs) are mainly formed in the dust shells of late stages of AGB type carbon rich stars. After the ejection of H-rich envelope those stars become the proto-planetary nebulae (PPNs). The chemistry in PPNs has been strongly modified by the UV photons coming from the hot central star and by the X-rays associated with its high-velocity winds. Benzene (C6H6) and small PAHs like Anthracene (C14H10) were effectively detected in the PPNs CRL 618 (Cernicharo et al. 2001) and Red Rectangle (Vijh, Witt & Gordon 2004) respectively. The goal of this work is to experimentally study photoabsorption, photoionization and photodissociation processes of the benzene, biphenyl (C12H10), naphthalene (C10H8), phenanthrene (C14H10) and methyl-anthracene (C14H9(CH3)). The measurements were taken at the Brazilian Synchrotron Light Laboratory (LNLS), using soft X-ray and UV photons from a toroidal grating monochromator TGM beamline (12-310 eV). The experimental set-up consists of a high vacuum chamber with a Time-Of-Flight Mass Spectrometer (TOF-MS). Mass spectra were obtained using PhotoElectron PhotoIon Coincidence (PEPICO) technique. Kinetic energy distributions and abundances for each ionic fragment have been obtained from the analysis of the corresponding peak shapes in the mass spectra. Dissociative and non-dissociative photoionization cross sections for some molecules were also determined (see for example: Boechat-Roberty, Pilling & Santos 2005). We have observed that PAHs molecules are extreme resistant to UV photons, confirming that PAHs absorb the UV photons and after some internal energetic rearrangements, they can emit in the IR range. However, these molecules are destroyed by soft X-rays photons producing several ionic fragments, some of them with great kinetic energy. In the mass spectra of the Benzene and methyl-anthracene molecules, the observed ionic fragments C4H2+, C6H2+, C4HCH3 and C2HCH3, could correspond to the same ions and radicals detected in the CRL 618 (Cernicharo et al. 2001). This result also points out the possibility of PAHs and PAHs methylated can be actively present in those environments. From the photodissociation cross sections and the stellar radiation field we have determined the photodissociation rate and the half-life, as well as its upper limit abundance of the benzene molecule in the CRL618. The relative yields of some key fragments together their observed abundances in the astrophysical target allow to estimate an upper limit of father molecules in those regions.

Boechat-Roberty, H. M.; Neves, R.; Pilling, S.; de Souza G. G., B.; Lago, A.

156

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

157

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. PMID:24764175

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

2014-08-01

158

Optical and infrared emission of H II complexes as a clue to PAHs lifecycle  

E-print Network

We present an analysis of optical spectroscopy and infrared aperture photometry of more than 100 H II complexes in nine galaxies. Spectra obtained with the 6-m telescope of SAO RAS are used along with archival data from Spitzer and several ground-based telescopes to infer a strength of polycyclic aromatic hydrocarbon (PAH) emission, age, properties of the UV radiation field, and metallicity of studied H II complexes. Physical properties (age, radiation field parameters, metallicity) are related to the $F_{8}/F_{24}$ ratio used as a proxy for the PAH abundance in order to reveal factors that may influence the PAH evolution in H II complexes. The well-known correlation between the $F_{8}/F_{24}$ ratio and metallicity is confirmed in the studied complexes. The infrared flux ratio also correlates with the [O III]$\\lambda 5007/\\mathrm{H\\beta}$ ratio which is often considered as an indicator of the radiation field hardness, but this correlation seems to be a mere reflection of a correlation between [O III]$\\lambda ...

Khramtsova, M S; Lozinskaya, T A; Egorov, O V

2014-01-01

159

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

160

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

161

Preferential surfactant utilization by a PAH-degrading strain: effects on micellar solubilization phenomena.  

PubMed

Biodegradable nonionic Tween series surfactants were employed to assess the effects of synthetic surfactants on the bioavailability of a target polycyclic aromatic hydrocarbon (PAH), phenanthrene, in soil/sediment-free micellar solutions. Dosages of surfactants in excess of their respective critical micelle concentrations (CMCs) dramatically enhanced solubilization of phenanthrene, but the micellar-solubilized phenanthrene was neither directly nor readily bioavailable to the PAH-degrading strain, Sphingomonas paucimobilis EPA 505, used in these bioavailability experiments. The microorganism preferred instead to utilize hydrophobic fractions of the Tween surfactants as a carbon source, resulting in an imbalance of amphiphilic moieties in surfactant molecules and associated destabilization of micelles. This effect was assessed by measurements of surface tension, CMCs, weight-based PAH solubilization ratios, and by characterizations of the surfactants via HPLC separation and emulsification behavior. The observations and analyses lead to a conclusion that preferential biological destabilization of surfactant micelles effects an associated release of phenanthrene to the aqueous phase. The phenanthrene so released then apparently reverts to a crystallized form that appears to be bioavailable only through normal re-dissolution to the aqueous phase. This is, to our knowledge, the first attempt to characterize and quantify changes in the properties and solubilization behaviors of surfactant micelles resulting from their partial and preferential biodegradation. The associated re-deposition of previously micellar-solubilized PAHs observed and the loss of solubilization capacity of recovered surfactants have significant implications for applications of surfactant-enhanced bioremediation of contaminated soils and sediments. PMID:12953868

Kim, Han S; Weber, Walter J

2003-08-15

162

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

163

Bioventing PAH contamination at the Reilly Tar Site  

SciTech Connect

A pilot-scale bioventing demonstration has been in progress since November 1992 to determine if bioventing is an effective remediation treatment for polycyclic aromatic hydrocarbons (PAHs). The Reilly Tar and Chemical Corporation site in St. Louis Park, Minnesota, was selected for this demonstration. The location is the site of a former coal tar refinery and wood-preserving facility at which creosote in mineral oil served as the primary preservative. The goal of the project is to achieve 10% greater PAH removal over background degradation for each year of the 3-year study. Respiration measurements were made to estimate PAH biodegradation as a means of monitoring the progress of the technology. These measurements indicated that 13.4% and 17.3% degradation of the total PAH was possible during the first year and second year, respectively. Although not all of the respiration can be attributed conclusively to PAH metabolism, strong correlations were found between the PAH concentration and biodegradation rates.

Alleman, B.C.; Hinchee, R.E. [Battelle Columbus, OH (United States); Brenner, R.C.; McCauley, P.T. [Environmental Protection Agency, Cincinnati, OH (United States). National Risk Management Research Lab.

1995-12-31

164

Recombination Rates of Electrons with Interstellar PAH Molecules  

NASA Technical Reports Server (NTRS)

The goal of this project is to develop a general model for the recombination of electrons with PAH molecules in an interstellar environment. The model is being developed such that it can be applied to a small number of families of PAHs without reference to specific molecular structures. Special attention will be focused on modeling the approximately circular compact PAHs in a way that only depends on the number of carbon atoms.

Ballester, Jorge (Cartographer)

1996-01-01

165

PAH emission from the incineration of three plastic wastes  

Microsoft Academic Search

A batch-type, controlled-air incinerator was used for the treatment of polyvinyl chloride (PVC), high-density polyethylene (HDPE), and polypropylene (PP) plastic wastes. The concentration and composition of 21 individual polycyclic aromatic hydrocarbons (PAHs) in the raw wastes, flue gas (gas and particle phases), and ash were determined. Stack flue-gas samples were collected by a PAH stack-sampling system. Twenty-one individual PAHs were

Chun-Teh Li; Huan-Kai Zhuang; Lien-Te Hsieh; Wen-Jhy Lee; Meng-Chun Tsao

2001-01-01

166

New PAH mode at 16.4 microns  

E-print Network

The detection of a new 16.4 micron 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 micron feature could be assigned to low-frequency vibrations of PAHs. The best carrier candidates seem to be PAH molecules containing pentagonal rings.

C. Moutou; L. Verstraete; A. Leger; K. Sellgren; W. Schmidt

1999-12-30

167

The 1 1S-n 1 P/1 1S-2 1 P emission-line ratios in Si XIII as electron temperature diagnostics for solar flares and active regions  

SciTech Connect

Theoretical Si XIII emission-line ratios R1, R2, and R3 are presented as a function of electron temperature. These ratios are found to be more electron temperature sensitive than the commonly used diagnostic for He-like ions (G), with, for example, R1, R2, and R3 varying by factors of approximately 6, 12, and 17 between log Te = 6.2 and 7.2, while G only changes by a factor of 1.8. In addition, R1, R2, and R3 are less dependent on whether or not the Si XIII-emitting plasma is in ionization equilibrium. Electron temperatures deduced using the observed values of R1, R2, and R3 from OV 1-17 and OSO 8 satellite spectra of solar flares and active regions are in good agreement and, in general, compared favorably with those determined from G. However, in the case of measurements made with the Flat Crystal Spectrometer on board the Solar Maximum Mission satellite there are large discrepancies between theory and observation. Possible explanations for these are briefly discussed. 19 refs.

Keenan, F.P.; Mccann, S.M.; Phillips, K.J.H. (Belfast Queen's Univ. (England) Rutherford Appleton Laboratory, Didcot (England))

1990-11-01

168

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  

Microsoft Academic Search

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

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

2007-01-01

169

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

170

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

171

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.

172

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

173

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

Microsoft Academic Search

The heterogeneous reactions of typical polycyclic aromatic hydrocarbons (PAHs) and their derivatives (nitro-, oxy-, and hydroxy-PAHs) adsorbed on azelaic acid particles with NO3 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

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

2011-01-01

174

Distribution and location of polycyclic aromatic hydrocarbons (PAHs) and PAH-degrading bacteria within polluted soil aggregates  

Microsoft Academic Search

A study was conducted to determine the location and distribution of PAH and PAH-degrading bacteria in different aggregate size fractions of an industrially polluted soil. The estimation of PAH-degrading bacteria using an MPN microplate technique indicated that these bacteria are most numerous in the aggregate size fractions corresponding to fine silt (2–20µm) and clay(2 etc.). Based on these findings, soil

Najat Amellal; Jean-M. Portal; Timothy Vogel; Jacques Berthelin

2001-01-01

175

Compound-specific radiocarbon analysis to evaluate the contribution of Peace River floodings to the PAH background in the Peace-Athabasca Delta  

NASA Astrophysics Data System (ADS)

The oil sands of Northern Alberta, Canada are one of the largest hydrocarbon reserves in the world. The rapid growth of the bitumen exploitation in this region involves large scale mining infrastructure, raising questions about the environmental impact of these operations. One of the main issues is the emission of hazardous organic compounds such as polycyclic aromatic hydrocarbons (PAHs). PAHs, which are found naturally in petroleum, are also produced through incomplete combustion and diagenesis of organic matter. The complex nature of the surrounding geology (natural levels of bitumen) requires tools able to discriminate sources of pollutants. The establishment of the PAH background is crucial in order to investigate the impacts of oil sands mining in the Athabasca region. Here we present a new approach to discriminate the sources of alkylated PAHs (fossil or modern biomass) and their relative contributions. Using a dated sediment sequence from a lake situated in the Peace-Athabasca Delta periodically flooded by the Peace River, 6 different groups of parent and alkylated PAHs were extracted and collected by preparative capillary gas chromatography (PCGC) for natural abundance radiocarbon (14C) measurement. Three grouped layers each comprising approximately 10 years of sedimentation and spanning the period of mining operations (i.e., the past 40 years) were analyzed. We report here the first use of 14C measurements on alkylated PAHs extracted from lake sediments. Our results showed low radiocarbon content for all alkylated and parent PAHs analyzed in the three sediment layers. However, a slight trend toward a more modern PAH input can be seen up-core. PAH isomers ratios pointed to a major influence of petroleum input in the entire lake sequence, supporting the predominance of a fossil carbon source as indicated by the low radiocarbon contents. As the Peace River cuts through the Peace oil sands formation, our results can be explained by the main contribution of PAHs originating from periodic flooding events as previously documented for this lake. We further interpret the modern proportion of alkylated PAHs as being contributed from forest fires. These results provide greater insight into the variability of the alkylated PAH sources, and highlight the potential of this isotopic technique for source apportionment of airborne PAHs in lakes from the Athabasca oil sands region.

Jautzy, J. J.; Ahad, J. M.; Hall, R. I.; Wiklund, J. A.; Gobeil, C.; Savard, M. M.

2013-12-01

176

Bioaccumulation and critical body residue of PAHs in the amphipod, Diporeia spp.: additional evidence to support toxicity additivity for PAH mixtures  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs) are considered to act additively when exposed as congener mixtures. Additive internal concentrations at the site of toxic action is the basis for recent efforts to establish a sum PAH guideline for sediment-associated PAH toxicity. This study determined the toxicity of several PAH congeners on a body residue basis in Diporeia spp. These values were compared

Peter F. Landrum; Guilherme R. Lotufo; Duane C. Gossiaux; Michelle L. Gedeon; Jong-Hyeon Lee

2003-01-01

177

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...

178

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

179

The use of limpets as monitor of PAHs pollution in the Cantabrian coast  

NASA Astrophysics Data System (ADS)

The concentrations of 24 parental and methylated polycyclic aromatic hydrocarbon (PAH) levels in common limpet ( Patella vulgata) were measured in 15 coastal localities of the southern Bay of Biscay and 2 sites per locality for 2 years (spring and autumn of 2004 and 2005, respectively). Although the average concentrations shown a wide variability among the sites and the season, several sites showed a remarkable high concentration (PAH tot>900 ng g -1 d.w.) or medium (300-800 ng g -1 d.w) levels, but in most of the cases the initial high concentrations decreased sharply from one campaign to the following. Moreover, based on ratios of individual isomers concentration, petrogenic and pyrolitic sources were distinguished suggesting more than one source. Finally, based on the results of this work and comparing with previously reported data, it can concluded that limpets can be used as sentinel organisms in coastal environmental monitoring, even when oil spills are involved.

Bartolomé, L.; Bustamante, M.; Navarro, P.; Tajadura, J.; Gorostiaga, J. M.; Díez, I.; Zuloaga, O.; Etxebarria, N.

2011-11-01

180

Chemical characteristic and toxicity assessment of particle associated PAHs for the short-term anthropogenic activity event: During the Chinese New Year's Festival in 2013.  

PubMed

PM10 and PM2.5 samples were simultaneously collected during a period which covered the Chinese New Year's (CNY) Festival. The concentrations of particulate matter (PM) and 16 polycyclic aromatic hydrocarbons (PAHs) were measured. The possible source contributions and toxicity risks were estimated for Festival and non-Festival periods. According to the diagnostic ratios and Multilinear Engine 2 (ME2), three sources were identified and their contributions were calculated: vehicle emission (48.97% for PM10, 53.56% for PM2.5), biomass & coal combustion (36.83% for PM10, 28.76% for PM2.5), and cook emission (22.29% for PM10, 27.23% for PM2.5). An interesting result was found: although the PAHs are not directly from the fireworks display, they were still indirectly influenced by biomass combustion which is affiliated with the fireworks display. Additionally, toxicity risks of different sources were estimated by Multilinear Engine 2-BaP equivalent (ME2-BaPE): vehicle emission (54.01% for PM10, 55.42% for PM2.5), cook emission (25.59% for PM10, 29.05% for PM2.5), and biomass & coal combustion source (20.90% for PM10, 14.28% for PM2.5). It is worth to be noticed that the toxicity contribution of cook emission was considerable in Festival period. The findings can provide useful information to protect the urban human health, as well as develop the effective air control strategies in special short-term anthropogenic activity event. PMID:24632060

Shi, Guo-Liang; Liu, Gui-Rong; Tian, Ying-Ze; Zhou, Xiao-Yu; Peng, Xing; Feng, Yin-Chang

2014-06-01

181

CHILDREN'S AGGREGATE EXPOSURE TO POLYCYCLIC AROMATIC HYDROCARBONS (PAHS)  

EPA Science Inventory

Polycyclic aromatic hydrocarbons (PAHs) have been frequently detected at children's homes and day care centers and may pose health concerns due to their carcinogenicity. Most PAHs have been persistent indoors and outdoors, therefore, children may be exposed to chronic low level...

182

The effects of PAH contamination on soil invertebrate communities  

SciTech Connect

Soils were collected from an abandoned industrial site to study the effects of historic polycyclic aromatic hydrocarbons (PAHs) on soil invertebrate communities. Nematode abundance and diversity, microarthropod abundance (orders Collembola and Acarina) and earthworm growth were evaluated. Physical and chemical characteristics of soils may affect both invertebrate community structure and the mobility/bioavailability of pollutants in soils. Soil characteristics were measured and included with PAH data in multiple regression analyses to identify factors which influences the responses observed in the soil invertebrate community. Positive associations were observed between eight invertebrate community endpoints and soil PAH content. For all of these endpoints but one, a higher degree of variability was explained when both PAH content and soil characteristics were considered. It is theorized that the positive response to soil PAH content may be the result of an increased abundance of PAH-degrading soil microbes. Increased microbial abundance could stimulate invertebrate communities by providing a direct food source or increasing the abundance of microbially-produced nutrients. These results suggest that both PAH content and soil characteristics significantly influenced the soil invertebrate community. It is not clear whether these factors influenced the invertebrate community independently, or whether differences in soil characteristics affected the community response by influencing the mobility or bioavailability of PAHs.

Snow-Ashbrook, J.L.; Erstfeld, K.M. [Rutgers Univ., New Brunswick, NJ (United States). Dept. of Environmental Sciences

1995-12-31

183

Limited Roles for Salicylate and Phthalate in Bacterial PAH Bioremediation  

Microsoft Academic Search

We have isolated and identified 12 previously unreported strains of polycyclic aromatic hydrocarbon (PAH)-degrading bacteria. Three of these isolates belong to the genus Burkholderia, with the remainder comprised of two Pseudomonas species, and seven strains from the genus Sphingomonas. These isolates were examined for their ability to utilize a variety of three- to five-ring PAHs as sole sources of carbon

Bill W. Bogan; Lisa M. Lahner; J. Robert Paterek

2001-01-01

184

Dissolved Oxygen Saturation Controls PAH Biodegradation in Freshwater Estuary Sediments  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs) are common contaminants in terrestrial and aquatic environments and can represent a significant constituent of the carbon pool in coastal sediments. We report here the results of an 18-month seasonal study of PAH biodegradation and heterotrophic bacterial production and their controlling biogeochemical factors from 186 sediment samples taken in a tidally influenced freshwater estuary. For each

T. J. Boyd; M. T. Montgomery; J. K. Steele; J. W. Pohlman; S. R. Reatherford; B. J. Spargo; D. C. Smith

2005-01-01

185

Enhanced bioremediation of PAH contaminated soils from coal processing sites  

SciTech Connect

The polycyclic aromatic hydrocarbons (PAH) are a potential hazard to health due to their carcinogenic, mutagenic nature and acute toxicity and there is an imminent need for remediation of PAH contaminated soils abounding the several coke oven and town gas sites. Aerobic biological degradation of PAHs is an innovative technology and has shown high decontamination efficiencies, complete mineralization of contaminants, and is environmentally safe. The present study investigates the remediation of PAH contaminated soils achieved using Acinetobacter species and fungal strain Phanerochaete Chrysosporium. The soil used for the experiments was an industrially contaminated soil obtained from Alberta Research Council (ARC) primary cleanup facility, Alberta, Canada. Soil characterization was done using High Performance Liquid Chromatography (HPLC) to qualitatively and quantitatively determine the contaminants in the soil. Artificially contaminated soil was also used for some experiments. All the experiments were conducted under completely mixed conditions with suitable oxygen and nutrient amendments. The removal efficiency obtained for various PAHs using the two microorganisms was compared.

Joshi, M.M.; Lee, S. [Univ. of Akron, OH (United States)

1995-12-31

186

Polycyclic Aromatic Hydrocarbons (PAHs): Degradation and Fungal Biomass (Ergosterol) in Sediment with added Nitrogen.  

E-print Network

??White rot fungi, Pleurotus ostreatus, is capable of degrading a wide range of organic contaminants including PAHs. Bioremediating polycyclic aromatic hydrocarbons (PAH) contaminated river sediment… (more)

Osama, Mohammad

2009-01-01

187

Photoinduced Toxicity of PAHs and Alkylated PAHs to a Marine Infaunal Amphipod ( Rhepoxynius abronius )  

Microsoft Academic Search

.   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\\u000a (LC50 values) and the ability to rebury in control sediment (EC50 values) were determined. Survivors of these initial toxicity tests were then exposed to UV radiation in an environmental\\u000a growth chamber for 1 h. The

B. L. Boese; J. O. Lamberson; R. C. Swartz; R. Ozretich; F. Cole

1998-01-01

188

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

NASA Astrophysics Data System (ADS)

The off-line Eulerian AURAMS chemical transport model was adapted to simulate the atmospheric fate of seven PAHs: 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, eight of which 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. 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. Model performance differed substantially between measurement locations and the limited available evidence suggests that the model 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.

2013-07-01

189

Isolation and Optimization of PAH-Degradative Bacteria from Contaminated Soil for PAHs Bioremediation  

Microsoft Academic Search

The objective of the present study is to isolate PAH-degradativebacteria from petroleum-contaminated soils and to optimize theirdegradative conditions including pH, glucose, nitrogen andphenanthrene concentrations required for bioremediationpurposes. Several bacterial strains were isolated throughenrichment and one strain, Burkholderia cocovenenans (BU-3)that was tentatively identified by the Biolog system,demonstrated a high removal rate of phenanthrene over otherstrains. More than 95% in 100 and

J. W. C. Wong; K. M. Lai; C. K. Wan; K. K. Ma; M. Fang

2002-01-01

190

Infrared absorption and emission characteristics of interstellar PAHs  

NASA Technical Reports Server (NTRS)

The mid-infrared interstellar emission spectrum with features at 3.28, 6.2, 7.7, 8.7 and 11.3 microns is discussed in terms of the Polycyclic Aromatic Hydrocarbon (PAH) hypothesis, which is based on the suggestive, but inconclusive comparison between the interstellar emission spectrum with the infrared absorption and Raman spectra of a few PAHs. The fundamental vibrations of PAHs and PAH-like species which determine the IR and Raman properties are discussed. Interstellar IR band emission is due to relaxation from highly vibrationally excited PAHs excited by ultraviolet photons. The excitation/emission process is described and the IR fluorescence from one PAH, chrysene, is traced. Generally, there is sufficient energy to populate several vibrational levels in each mode. Molecular vibrational potentials are anharmonic and emission from these higher levels will fall at lower frequencies and produce weak features to the red of the stronger fundamentals. This process is also described and can account for some spectroscopic details of the interstellar emission spectra previously unexplained. Analysis of the interstellar spectrum shows that PAHs contain between 20 and 30 carbon atoms are responsible for the emission.

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

1986-01-01

191

Gaseous and adsorbed PAH in an iron foundry.  

PubMed Central

The increased risk of lung cancer among foundry workers is assumed to be associated with the inhalation of gaseous and particle bound polycyclic aromatic hydrocarbons (PAH). These compounds are produced during pyrolysis of carbon containing loading material in the moulding sand. The concentrations of 20 PAH, some of which are carcinogenic, have been determined in the dusty casting area of an iron foundry by means of gas chromatography and mass spectrometry. The total dust was fractionated by means of a precision cascade impactor. It was possible to differentiate the PAH load in microgram/mg dust in seven particle size fractions ranging from 0.36- greater than or equal to 24.95 microns. Initially, there was an increase of the adsorbed PAH mass concentration with increasing particle diameter up to a maximum of 1.1 microgram/mg in the dust of the 1.57 micron fraction. Thereafter there was a continuous decrease of PAH mass concentration with increasing particle size. When the differing weights of the seven fractions are taken into account, however, the total PAH load of the individual fractions increases steadily with increasing particle size. The inhalable fine dust, 31.4% of the total dust, contains 49.9% of the total adsorbed PAH. The gas phase contained on average three times more carcinogenic PAH with four and five rings than was adsorbed on the dust. Thus the percentage of the gaseous substances amounts to 77% of the total PAH load at the place of work in an iron foundry. PMID:3801335

Knecht, U; Elliehausen, H J; Woitowitz, H J

1986-01-01

192

Photoinduced degradation of PAHs in the presence of ozone  

SciTech Connect

Polycyclic Aromatic Hydrocarbons (PAH) are formed from both anthropogenic and natural sources. In order to assess the environmental impact caused by the surface-adsorbed PAHs, the chemical lifetimes of these compounds in the atmosphere must be determined. Although ozone is known to be a primary reactant in the chemical transformation of surface-adsorbed PAHs in the atmosphere, the kinetics of these reactions have not been investigated in detail. In addition to the experimental difficulties that arise in using an oxygen-ozone stream while monitoring the PAH with fluorescence, complications in analyzing the kinetic mechanism also exist. It is difficult to determine whether the ozone or oxygen initially quenches the excited state of PAH. Ozone could enhance the degradation rate by simply reacting with a product derived from the excited state of PAH and oxygen. The focus of this study is to demonstrate the use of fluorescence spectroscopy in monitoring the degradation of PAH adsorbed on a three dimensional particle in the presence of gaseous ozone free from the interference of oxygen. More specifically, the experimental procedure will involve the generation of an ozone-nitrogen gas stream to be used in the investigation of dark and photochemical reactions between ozone and naphthalene. The absence of oxygen in the system will allow for the accurate monitoring of PAH fluorescence decay due solely to ozone quenching. It will also aid in the determination of the reaction mechanism. This is the first time that the direct interaction of ozone with an excited state of PAH has been demonstrated.

Schutt, W.S.; Li, Y. [Clarkson Univ., Potsdam, NY (United States). Dept. of Chemistry; Sigman, M.E. [Clarkson Univ., Potsdam, NY (United States). Dept. of Chemistry]|[Oak Ridge National Lab., TN (United States). Chemistry Div.

1995-12-31

193

Sorption and chemical transformation of PAHs on coal fly ash. Final technical report  

SciTech Connect

The objectives of this work were to characterize the interactions of coal fly ash with polycyclic aromatic hydrocarbons (PAH`s) and their derivatives, and to attempt to understand the influence of surface properties of coal ash in the chemical transformations of PAH`s.

Mamantov, G.; Wehry, E.L.

1995-02-01

194

Interfacial effects in a two-phase partitioning bioreactor: degradation of polycyclic aromatic hydrocarbons (PAHs)  

E-print Network

-organic interface. Results showed that agitation rate affected cell growth and PAH degradation rates, while. # 2004 Elsevier Ltd. All rights reserved. Keywords: Mycobacterium; PAH; Degradation; Partitioning by dissolving PAHs in a dispersed organic phase, and the highest PAH degradation rates recorded

Daugulis, Andrew J.

195

Biodegradation of sediment-bound PAHs in field-contaminated sediment  

Microsoft Academic Search

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 where PAHs were freshly spiked, and biodegradation was often tested using pure cultures or enrichments. This paper investigated the degradation potentials of PAHs

L. Lei; A. P. Khodadoust; M. T. Suidan; H. H. Tabak

2005-01-01

196

Concentration of Polycyclic Aromatic Hydrocarbons (PAHs) in Moss (Hypnum cupressiforme) from Hungary  

Microsoft Academic Search

Mosses of the species Hypnum cupressiforme were collected from different parts of Hungary to investigate the air quality of the region. The concentrations of polycyclic aromatic hydrocarbons (PAHs) in species were determined. Low molecular weight PAHs (up to three ring compounds) contribute more than 99% to the concentrations of PAHs in Moss samples. The pattern of PAHs suggests local sources

Imre Olivér Kozák; Melinda Kozák; Jen? Fekete; Virender K. Sharma

2003-01-01

197

Polycyclic aromatic hydrocarbons (PAHs) in subcutaneous biopsies of Mediterranean cetaceans  

E-print Network

PAHs as priority pollutants. They are released into the environment by natural (pyrolysis, diagenesis, biosynthesis, natural seepage) and man-made processes (industrial processes, combustion of wood and fossil

Hahn, Mark E.

198

POLYCYCLIC AROMATIC HYDROCARBON (PAH) EXPOSURE OF 257 PRESCHOOL CHILDREN  

EPA Science Inventory

We investigated the polycyclic aromatic hydrocarbon (PAH) exposure of 257 preschool children and their adult caregivers in their everyday environments. Participants were recruited randomly from eligible homes and daycare centers within six North Carolina (NC) and six Ohio (OH) c...

199

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

200

Semivolatiles in the Forest Environment: The Case of PAHs  

Microsoft Academic Search

\\u000a Forests are an important sink for semivolatile organic compounds (SVOCs) due to the great aerodynamic roughness of woodland\\u000a landscape which enhances downward fluxes of both gaseous and particle-bound pollutants and the slow turnover of soil organic\\u000a content. In particular, Polycyclic Aromatic Hydrocarbons (PAHs) are the most abundant persistent organic toxics in forests.\\u000a Due to their lipophilic properties PAHs accumulate in

Claudio A. Belis; Ivo Offenthaler; Peter Weiss

201

Bacteria-mediated PAH degradation in soil and sediment  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the natural environment and easily accumulate in soil and sediment\\u000a due to their low solubility and high hydrophobicity, rendering them less available for biological degradation. However, microbial\\u000a degradation is a promising mechanism which is responsible for the ecological recovery of PAH-contaminated soil and sediment\\u000a for removing these recalcitrant compounds compared with chemical degradation

Xiao-Ying Lu; Tong Zhang; Herbert Han-Ping Fang

2011-01-01

202

Prediction of PAH mutagenicity in human cells by QSAR classification  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants of high environmental concern. The experimental data of a mutagenicity test on human B-lymphoblastoid cells (alternative to the Ames bacterial test) for a set of 70 oxo-, nitro- and unsubstituted PAHs, detected in particulate matter (PM), were modelled by Quantitative Structure-Activity Relationships (QSAR) classification methods (k-NN, k-Nearest Neighbour, and CART, Classification and Regression

E. Papa; P. Pilutti; P. Gramatica

2008-01-01

203

Polycyclic Aromatic Hydrocarbon (PAH) Degradation Coupled to Methanogenesis  

Microsoft Academic Search

Baltimore Harbor (Baltimore, MD) sediments were utilized to initiate anaerobic enrichment cultures with polycyclic aromatic\\u000a hydrocarbons (PAHs) in the absence of supplementary electron acceptors. Cultures amended with naphthalene and phenanthrene\\u000a exhibited sustained, transferable degradation of the PAHs. Bromoethanesulfonic acid, a selective inhibitor of methanogenesis,\\u000a inhibited the degradation of 200 ?m naphthalene and phenanthrene; molecular characterization based on 16S rRNA sequences confirmed

Wook Chang; Youngsoon Um; Tracey R. Pulliam Holoman

2006-01-01

204

Gas/particle partitioning of n-alkanes, PAHs and oxygenated PAHs in urban Denver  

NASA Astrophysics Data System (ADS)

In this study, a medium volume sampler equipped with quartz fiber filters (QFFs) and a polyurethane foam (PUF)/XAD-4/PUF sandwich (PXP) was used to collect semi-volatile organic compounds (SVOCs) in both gaseous and particle (PM2.5) phases. A backup QFF (bQFF) was used to evaluate possible sampling artifact of particulate organics due to vapor-phase adsorption. A series of n-alkanes (molecular weight: 170-562) and PAHs (128-300), and two oxy-PAHs (acenaphthenone, 168; fluorenone, 180) were measured. Breakthrough experiments demonstrated that the PXP could collect all gas-phase target compounds with high efficiency, even the low molecular weight (MW) species (e.g., naphthalene). Comparing species concentrations across different sampling matrices encountered at the Denver, Colorado field site, the light n-alkanes (MW < 282) and PAHs (MW < 192) were mostly distributed into the gas phase; while those heavy n-alkanes (MW > 324) and PAHs (MW > 202) were primarily in the particle phase (Average temperature, 12.5 ± 10.1 °C). Log values of measured gas/particle (G/P) partitioning coefficients (Kmp,OM) of selected SVOCs (docosane, tricosane, fluoranthene, pyrene, acenaphthenone and fluorenone) were linearly regressed to those of theoretically-based partitioning coefficients (Ktp,OM) for comparison. Prior to Kmp,OM calculation, the gas- and particle-phase concentrations of SVOCs were corrected following two different approaches based on bQFF measurements. The first approach assumed that the bQFF associated SVOCs were from the adsorption of gaseous SVOCs (positive artifact); the second approach assumed equal contributions from positive and negative (organics evaporated from top QFF and adsorbed by bQFF) artifacts. Under both corrections, significant correlations (p < 0.05) were observed between log Kmp,OM and log Ktp,OM for the six selected SVOCs, suggesting that the predicted G/P partitioning can reasonably capture the measured G/P partitioning behavior. The large deviations (1-2 orders of magnitudes) between Kmp,OM and Ktp,OM for acenaphthenone and fluorenone might be caused by the assumption of ideality (activity coefficient = 1) and the over prediction of vapor pressures (for Ktp,OM calculation). Negative correlations were observed between regression residuals of log Kmp,OM vs. log Ktp,OM and relative humidity, which might be attributed to the use of a constant activity coefficient and the possibility of phase separation.

Xie, Mingjie; Hannigan, Michael P.; Barsanti, Kelley C.

2014-10-01

205

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

206

Hydrogenation of PAH molecules through interaction with hydrogenated carbonaceous grains.  

PubMed

Carbonaceous materials contribute to a significant proportion of the interstellar dust inventory. Reactions on such grain surfaces are thought to play important roles in interstellar chemical networks. Of particular importance are reactions involving hydrogen atoms, and pathways to the formation of the most abundant molecular species, H2. Polycyclic aromatic hydrocarbons (PAHs) are an additional carbon reservoir, accounting for around 10% of the galactic carbon budget. Using thermal desorption and mass spectrometric techniques, we have investigated the interaction between PAH molecules and carbonaceous grain surfaces. We demonstrate that deuterium atoms adsorbed on graphite can react with adsorbed PAH molecules, forming superhydrogenated PAH species. Furthermore, by considering the number of D-atoms remaining bound to the graphite surface and the additional D-atoms in the observed superhydrogenated species, we see evidence for a significant release of deuterium from the graphite surface. We suggest that further reactive processes may be responsible for part of this deuterium loss, indicating that PAHs adsorbed on hydrogenated carbonaceous grains in warm interstellar environments may serve as a route to release H2 as well as forming superhydrogenated PAH species. PMID:24270708

Thrower, John D; Friis, Emil E; Skov, Anders L; Jørgensen, Bjarke; Hornekær, Liv

2014-02-28

207

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

208

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.

209

Rod Ratios  

NSDL National Science Digital Library

This activity builds student knowledge of ratios by using Cuisenaire rods to determine proportion and form equivalent ratios. Students may use the Cuisenaire rod environment embedded in this resource or they may use actual Cuisenaire rods depending on preference/ability/accessibility. This resource includes teacher notes, solution, and suggestions for questioning.

Team, Nrich

2013-01-01

210

Sedimentary organic biomarkers suggest detrimental effects of PAHs on estuarine microbial biomass during the 20th century in San Francisco Bay, CA, USA  

USGS Publications Warehouse

Hydrocarbon contaminants are ubiquitous in urban aquatic ecosystems, and the ability of some microbial strains to degrade certain polycyclic aromatic hydrocarbons (PAHs) is well established. However, detrimental effects of petroleum hydrocarbon contamination on nondegrader microbial populations and photosynthetic organisms have not often been considered. In the current study, fatty acid methyl ester (FAME) biomarkers in the sediment record were used to assess historical impacts of petroleum contamination on microbial and/or algal biomass in South San Francisco Bay, CA, USA. Profiles of saturated, branched, and monounsaturated fatty acids had similar concentrations and patterns downcore. Total PAHs in a sediment core were on average greater than 20× higher above ?200 cm than below, which corresponds roughly to the year 1900. Isomer ratios were consistent with a predominant petroleum combustion source for PAHs. Several individual PAHs exceeded sediment quality screening values. Negative correlations between petroleum contaminants and microbial and algal biomarkers – along with high trans/cis ratios of unsaturated FA, and principle component analysis of the PAH and fatty acid records – suggest a negative impacts of petroleum contamination, appearing early in the 20th century, on microbial and/or algal ecology at the site.

Nilsen, Elena B.; Rosenbauer, Robert J.; Fuller, Christopher C.; Jaffe, Bruce E.

2014-01-01

211

HELSINKI UNIVERSITY OF TECHNOLOGY ENE-47.153 VOCsVOCs,, PAHsPAHs, soot, tar, CO, soot, tar, CO  

E-print Network

-level ozone) and ground-level ozone ·· Control ofControl of VOCsVOCs ·· Formation and control of.hut.fi/~rzevenhorzevenho//gasbookgasbook HELSINKI UNIVERSITY OF TECHNOLOGY ENE-47.153 Definitions ofDefinitions of VOCsVOCs,, PAHsPAHs, tar, soot). methane) in Europe, 1994 (tonnes)in Europe, 1994 (tonnes) Ground-level ozone in Europe,Ground-level ozone

Zevenhoven, Ron

212

Adsorption of polycyclic aromatic hydrocarbons (PAHs) from isooctane solutions by mesoporous molecular sieves: Influence of the surface acidity  

Microsoft Academic Search

Three different mesoporous molecular sieves of MCM-41 type (a pure silica and two aluminum doped silica with Si\\/Al molar ratios of 10 and 30) were evaluated for adsorption of polycyclic aromatic hydrocarbons (PAHs) from an organic solution. The aluminum containing samples were synthesized at room temperature using a sol–gel method with two reaction steps: acid hydrolysis of the metallic alkoxides

R. S. Araújo; D. C. S. Azevedo; C. L. Cavalcante Jr.; A. Jiménez-López; E. Rodríguez-Castellón

2008-01-01

213

Unlike PAHs from Exxon Valdez crude oil, PAHs from Gulf of Alaska coals are not readily bioavailable  

SciTech Connect

In the wake of the 1989 Exxon Valdez oil spill, spatially and temporally spill-correlated biological effects consistent with polycyclic aromatic hydrocarbon (PAH) exposure were observed. Some works have proposed that confounding sources from local source rocks, prominently coals, are the provenance of the PAHs. Representative coal deposits along the southeast Alaskan coast (Kulthieth Formation) were sampled and fully characterized chemically and geologically. The coals have variable but high total organic carbon content, technically classifying as coals and coaly shale, and highly varying PAH contents. Even for coals with high PAH content (4000 ppm total PAHs), a PAH-sensitive bacterial biosensor demonstrates nondetectable bioavailability as quantified, based on naphthalene as a test calibrant. These results are consistent with studies indicating that materials such as coals strongly diminish the bioavailability of hydrophobic organic compounds and support previous work suggesting that hydrocarbons associated with the regional background in northern Gulf of Alaska marine sediments are not appreciably bioavailable. 44 refs., 4 figs., 2 tabs.

Halambage Upul Deepthike; Robin Tecon; Gerry van Kooten; Jan Roelof van der Meer; Hauke Harms; Mona Wells; Jeffrey Short [Tennessee Technological University, Cookeville, TN (United States). Department of Chemistry

2009-08-15

214

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

215

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

216

THE EFFECTS OF EQUIVALENCE RATIO ON THE FORMATION OF POLYCYCLIC AROMATIC HYDROCARBONS AND SOOT IN PREMIXED ETHANE FLAMES. (R825412)  

EPA Science Inventory

Abstract The formation of polycyclic aromatic hydrocarbons (PAH) and soot has been investigated in atmospheric-pressure, laminar, ethane/oxygen/argon premixed flames as a function of mixture equivalence ratio. Mole fraction profiles of major products, trace aromatics, ...

217

SOURCE APPORTIONMENT OF POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) INTO CENTRAL PARK LAKE, NEW YORK CITY, OVER A CENTURY OF DEPOSITION  

PubMed Central

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. PMID:24375577

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

2014-01-01

218

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. PMID:24375577

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

2014-05-01

219

Geochemical factors affecting PAH distribution in Chesapeake Bay sediments  

SciTech Connect

Sediment/pore water distribution coefficients (K{sub d}s) of selected polycyclic aromatic hydrocarbons (PAHs) were examined with depth at two sites in the Elizabeth River, a tributary of the Chesapeake Bay, Virginia. Areas of the Elizabeth River have been historically extensively contaminated with PAHs. Varying trends in distribution coefficients were observed both across the range of molecular weights of the PAHs and with depth in the sediment. Linear relations between log K{sub d} and octanol-water partition coefficient (log K{sub ow}) were observed deep in the cores but not near the surface of the sediments. This phenomena indicates that PAH sediment/porewater distributions are not at equilibrium near the sediment-water interface. Moreover, down-core K{sub d}s decreased and were, in most cases, inversely related with fraction organic carbon. These data indicate that dissolved organic carbon (DOC) may play a potentially significant role in mobilizing sediment-associated organic contaminants. The extent to which DOC and other geochemical parameters such as total lipid extract (TLE) and BET surface area control K{sub d}s of PAHs, is under further investigation.

Mitra, S.; Dickhut, R.M.; Kimbrough, K. [Coll. of William and Mary, Williamsburg, VA (United States)

1995-12-31

220

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

221

Induction of PAH degradation in a phenanthrene-degrading pseudomonad  

SciTech Connect

Recent evidence suggests that different polycyclic aromatic hydrocarbon (PAH) substrates are metabolized by common enzymes in PAH-degrading bacteria, implying that inducers for low-molecular-weight PAH degradation may coinduce for the metabolism of higher-molecular-weight compounds. The authors have tested this hypothesis with a well-characterized PAH-degrading bacterium, Pseudomonas saccharophila P-15. Growth of P-15 on salicylate, a metabolite of phenanthrene degradation, and a known inducer for naphthalene degradation, induced the metabolism of both substrates. Several potential inducers were then tested for their effects on metabolism of the four-ring compounds pyrene and fluoranthene, neither of which is a growth substrate for P-15, but both of which can be metabolized by this organism. Incubation of P-15 in the presence of phenanthrene or salicylate induced the metabolism of pyrene and fluoranthene in resting-cell assays. Catechol, another intermediate of naphthalene and phenanthrene degradation, did not induce the metabolism of either compound and interfered with the inducing effect of salicylate. These results have implications for strategies designed to maintain PAH degradation in contaminated environments, particularly for compounds that are degraded slowly or are degraded only by nongrowth metabolism.

Stringfellow, W.T. [Univ. of California, Berkeley, CA (United States). Dept. of Civil Engineering; Chen, S.H.; Aitken, M.D. [Univ. of North Carolina, Chapel Hill, NC (United States). Dept. of Environmental Science and Engineering

1995-12-31

222

Toxicity of atmospheric particle-bound PAHs: an environmental perspective.  

PubMed

Atmospheric polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants that represent a risk not only to humans, but to all living organisms. High-molecular weight PAHs are more toxic than lighter relatives, and also have a higher tendency to bind onto air particles (i.e., particle matter, PM). PM is a major constituent of air pollution. Adequate assessment of the biological impact of PM requires the analysis, not only of the effects on human health, but also on the environment. Since the aquatic systems work as a natural sink to these air pollutants, assessing the effects of particle-bound PAHs on aquatic organisms may further characterize its potential aquatic toxicity, also providing simple and low-cost alternative assays to investigate PM biological effects in vivo. We review the current scientific literature, addressing the atmospheric PAHs fate, transformation and deposition, pertinent particle-bound PAHs toxicity data, and the potential aquatic toxic burden. Conceptual and experimental procedures that could improve future investigations and risk assessments are also considered. PMID:24595747

Mesquita, Sofia Raquel; L van Drooge, Barend; Barata, Carlos; Vieira, Natividade; Guimarães, Laura; Piña, Benjamin

2014-10-01

223

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

224

Occurrence of priority hazardous PAHs in water, suspended particulate matter, sediment and common eels (Anguilla anguilla) in the urban stretch of the River Tiber (Italy).  

PubMed

This study investigated the occurrence of polycyclic aromatic hydrocarbons (PAHs) in water, suspended particulate matter (SPM), bed sediment and common eels (Anguilla anguilla) in the urban stretch of the River Tiber (Italy). The selected PAHs, fluoranthene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, benzo(g,h,i)perylene, indeno(1,2,3-cd)pyrene, belong to the EC priority list of dangerous substances. SPM was found to be the most polluted compartment, with values ranging from 1663.1 to 15472.9 ngg(-1) (?(6)PAHs), followed by sediment samples, from 157.8 to 271.6 ngg(-1) and by aqueous samples, from 23.9 to 72.0 ngL(-1). The distribution coefficient (K(d)) showed a good correlation with particle organic carbon (OC) content, while K(oc) values experimentally measured for sediment/SPM deviated from those predicted by K(ow), implying that for very hydrophobic compounds, K(ow) alone may not be an appropriate descriptor of all the thermodynamic forces involved in their sorption to aquatic particles. Some selected PAH ratios indicated that PAHs in the River Tiber come mainly from pyrolitic sources and vehicular traffic. Concentrations of individual PAHs in muscles of common eels varied from 0.8 to 7.0 ngg(-1) wet wt. and the calculated toxicity equivalent concentration (TEQ, 1.8 ngg(-1) wet wt.) of total PAHs fell below the recommended screening value (SV) in US EPA guidelines, suggesting no concern for human consumption. PMID:20932548

Patrolecco, Luisa; Ademollo, Nicoletta; Capri, Silvio; Pagnotta, Romano; Polesello, Stefano

2010-12-01

225

Diagnostic Teaching  

ERIC Educational Resources Information Center

Contends that teaching would be more effective if it became "diagnostic" teaching, that such teaching is not possible unless backed up with an adequate system of record keeping by the teacher, and that, conversely, the establishment by a school of such a record keeping system is likely to encourage diagnostic teaching. (Author/RK)

Cooper, Keith

1977-01-01

226

Polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs and related environmental compounds: Biological markers of exposure and effects  

SciTech Connect

Lung cancer caused by polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs and related environmental agents is a major problem in industrialized nations. The high case-fatality rate of the disease, even with the best supportive treatment, underscores the importance of primary lung cancer prevention. Development of biomarkers of exposure and effects to PAHs and related compounds is now underway and includes measurement of urinary metabolites of specific PAHs as well as detection of protein and DNA adducts as indicators of effective dose. Validation of these markers in terms of total environmental dose requires that concurrent measures of air levels and potential dermal exposure be made. In addition, the interrelationships between PAH biomarkers must be determined, particularly when levels of the marker in surrogate molecules (e.g., protein) or markers from surrogate tissues (e.g., lymphocyte DNA) are used to assess the risk to the target organ, the lung. Two approaches to biomarker studies will be reviewed in this article the progress made using blood lymphocytes as surrogates for lung tissues and the progress made developing noninvasive markers of carcinogen-DNA adduct levels in lung-derived cells available in bronchial-alveolar lavage and in sputum. Data are presented from studies in which exfoliated urothelial cells were used as a surrogate tissue to assess exposure to human urinary bladder carcinogens in occupational groups. 38 refs., 2 figs., 3 tabs.

Talaska, G.; Underwood, P.; Maier, A. [Univ. of Cincinnati Medical School, OH (United States)] [and others

1996-10-01

227

Phototransformation Rate Constants of PAHs Associated with Soot Particles  

PubMed Central

Photodegradation is a key process governing the residence time and fate of polycyclic aromatic hydrocarbons (PAHs) in particles, both in the atmosphere and after deposition. We have measured photodegradation rate constants of PAHs in bulk deposits of soot particles illuminated with simulated sunlight. The photodegradation rate constants at the surface (k0p), the effective diffusion coefficients (Deff), and the light penetration depths (z0.5) for PAHs on soot layers of variable thickness were determined by fitting experimental data with a model of coupled photolysis and diffusion. The overall disappearance rates of irradiated low molecular weight PAHs (with 2-3 rings) on soot particles were influenced by fast photodegradation and fast diffusion kinetics, while those of high molecular weight PAHs (with 4 or more rings) were apparently controlled by either the combination of slow photodegradation and slow diffusion kinetics or by very slow diffusion kinetics alone. The value of z0.5 is more sensitive to the soot layer thickness than the k0p value. As the thickness of the soot layer increases, the z0.5 values increase, but the k0p values are almost constant. The effective diffusion coefficients calculated from dark experiments are generally higher than those from the model fitting method for illumination experiments. Due to the correlation between k0p and z0.5 in thinner layers, Deff should be estimated by an independent method for better accuracy. Despite some limitations of the model used in this study, the fitted parameters were useful for describing empirical results of photodegradation of soot-associated PAHs. PMID:23247292

Kim, Daekyun; Young, Thomas M.; Anastasio, Cort

2013-01-01

228

Physical model for the photo-induced toxicity of polycyclic aromatic hydrocarbons (PAHs)  

SciTech Connect

A model for photo-induced toxicity of PAHs to duckweed was developed. Growth inhibition was described by photochemical reactions between PAHs and a hypothetical group of biomolecules (given the notation G) which are required for growth of the plants. Light activation of PAHs was considered in a two compartment system (water and leaves). The reaction scheme includes: photooxidation of PAHs, partitioning of PAHs into leaves, triplet formation of intact PAHs, photosensitization reactions that consume G, and reaction between photooxidized PAHs and G. The assumptions used in the model are: the rate of PAH photooxidation is slower than the rate of assimilation, PAH content in solution is approximately constant over the length of the toxicity test, the fluence rate of actinic radiation is lower in the leaves than in solution, the toxicity of intact PAHs with G in the absence of light is negligible, and the reaction of photooxidized PAHs with G does not require light. The authors then analyzed a series of differential equations that described toxicity. The result was an expression for growth inhibition as a function of the initial concentration of the PAH, the spectral distribution of the light source, the absorption spectrum of the PAH, the quantum yield for formation of triplet state PAH, and the rate of photo-oxidation of the PAH. The expression also includes two complex constants that can be solved by a least squares analysis of the empirical data for growth inhibition. Thus, the model allows a prediction of PAH photo-induced toxicity using only physical parameters of PAHs.

Greenburg, B.M.; Krylov, S.N.; Huang, H.D.; Dixon, D.G. [Univ. of Waterloo, Ontario (Canada)

1994-12-31

229

Atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) in mosses (Hypnum cupressiforme) in Hungary.  

PubMed

The atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) was investigated in Hungary by analyzing a moss (Hypnum cupressiforme) species as a bioindicator. In the autumn of 1997, samples were collected at 29 sites distributed across Hungary. The concentrations of total PAH at these sites were in the range of 0.1567-10.45 x 10(4) microg kg(-1) with a mean value of 1.87 x 10(4) microg kg(-1). More than 99% of the total PAHs atmospheric deposition were low molecular weight PAHs (up to 3 ring compounds). The total PAH values showed no correlation with metal concentrations. However, most of the sites in this region showed a positive linear relationship between PAHs levels and traffic volume (r2 = 0.83; P < 0.001) while no relationship existed between PAH levels and population (r2 = 0.01; P > 0.1). Atmospheric deposition of PAHs at different regions in Hungary may be due to incomplete combustion of fuel. The total concentrations of PAHs were compared to the PAH levels in vegetation samples collected from different regions around the world. The highest PAHs concentrations accumulated were found in Hypnum cupressiforme than other vegetation species. A greater affinity for PAH compounds by Hypnum cupressiforme than other moss species probably caused larger amounts of accumulation. A relationship between accumulations of PAH compounds in Hypnum cupressiforme and octanol-air partition coefficients was obtained and is briefly discussed. PMID:15325161

Otvös, E; Kozák, I O; Fekete, J; Sharma, V K; Tuba, Z

2004-09-01

230

Use of alternative growth substrates to enhance PAH degradation  

SciTech Connect

Freshwater and saltwater polycyclic aromatic hydrocarbons (PAH)-degrading enrichments were developed from seed from a manufactured gas plant site and contaminated marine sediment, respectively. Both enrichments were able to maintain specific degradation rates of 3- and 4-ring PAHs after growth with salicylate or phthalate, which increased their biomass concentrations by a factor of 9 to 10. Phthalate was a more effective alternative substrate than was salicylate. Specific degradation rates of phenanthrene and anthracene by the freshwater enrichment were increased after growth with phthalate. Growth with phthalate increased the specific degradation rates of phenanthrene and pyrene by the saltwater enrichment.

Tittle, P.C. [Gray and Osborne, Inc., Seattle, WA (United States); Liu, Y.T. [Environmental Protection Agency, Seattle, WA (United States); Strand, S.E.; Stensel, H.D. [Univ. of Washington, Seattle, WA (United States)

1995-12-31

231

First Detection of PAHs and Warm Molecular Hydrogen in Tidal Dwarf Galaxies  

NASA Astrophysics Data System (ADS)

We observed two faint tidal dwarf galaxies (TDGs), NGC 5291 N and NGC 5291 S, with the Infrared Spectrograph on the Spitzer Space Telescope. We detect strong polycyclic aromatic hydrocarbon (PAH) emission at 6.2, 7.7, 8.6, 11.3, 12.6, and 16.5 ?m, which match models of groups of ~100 carbon atoms with an equal mixture of neutral and ionized PAHs. The TDGs have a dominant warm (~140 K) dust component in marked contrast to the cooler (40-60 K) dust found in starburst galaxies. For the first time we detect the low-J rotational lines from molecular hydrogen. Adopting LTE, there is ~105 Msolar of ~400 K gas, which is <0.1% of the cold gas mass inferred from 12CO (1-0) measurements. The combination of one-third solar metallicity with a recent (<5 million year) episode of star formation is reflected in the S and Ne ratios. The excitation is higher than typical values for starburst galaxies and similar to that found in BCDs. Using the Infrared Array Camera, we identify an additional 13 PAH-rich candidate TDGs. These sources occupy a distinct region of IRAC color space with [3.6]-[4.5]<0.4 and [4.5]-[8.0]>3.2. Their disturbed morphologies suggest past merger events between companions; for example, NGC 5291 S has a projected 11 kpc tail. NGC 5291 N and S have stellar masses of (1.5 and 3.0)×108 Msolar, which is comparable to BCDs, although still roughly 10% of the LMC's stellar mass. The candidate TDGs are an order of magnitude less massive. This system appears to be a remarkable TDG nursery.

Higdon, S. J.; Higdon, J. L.; Marshall, J.

2006-04-01

232

Enhanced sorption of PAHs in natural-fire-impacted sediments from Oriole Lake, California.  

PubMed

Surface sediment cores from Oriole Lake (CA) were analyzed for organic carbon (OC), black carbon (BC), and their ?(13)C isotope ratios. Sediments displayed high OC (20-25%) and increasing BC concentrations from ?0.40% (in 1800 C.E.) to ?0.60% dry weight (in 2000 C.E.). Petrographic analysis confirmed the presence of fire-derived carbonaceous particles/BC at ?2% of total OC. Natural fires were the most likely cause of both elevated polycyclic aromatic hydrocarbon (PAH) concentrations and enhanced sorption in Oriole Lake sediments prior to 1850, consistent with their tree-ring-based fire history. In contrast to other PAHs, retene and perylene displayed decreasing concentrations during periods with natural fires, questioning their use as fire tracers. The occurrence of natural fires, however, did not result in elevated concentrations of black carbon or chars in the sediments. Only the 1912-2007 sediment layer contained anthropogenic particles, such as soot BC. In this layer, combining OC absorption with adsorption to soot BC (using a Freundlich coefficient n = 0.7) explained the observed sorption well. In the older layers, n needed to be 0.3 and 0.5 to explain the enhanced sorption to the sediments, indicating the importance of natural chars/inertinites in sorbing PAHs. For phenanthrene, values of n differed significantly between sorption to natural chars (0.1-0.4) and sorption to anthropogenic black carbon (>0.5), suggesting it could serve as an in situ probe of sorbents. PMID:21405084

Sullivan, Julia; Bollinger, Kevyn; Caprio, Anthony; Cantwell, Mark; Appleby, Peter; King, John; Ligouis, Bertrand; Lohmann, Rainer

2011-04-01

233

Biological risk and pollution history of polycyclic aromatic hydrocarbons (PAHs) in Nansha mangrove, South China.  

PubMed

Chinese government has taken various measures to alleviate pollution caused by polycyclic aromatic hydrocarbons (PAHs) in the region of Pearl River Delta since the economic reform in 1978, but the effectiveness of these measures remains largely unknown. This study aimed to elucidate the biological risk and pollution history of PAHs by measuring the concentrations of 28 PAHs in the surface and core sediments, respectively, in Nansha mangrove. Results found that the biological risk of PAHs was low without obvious spatial variation. The PAH concentration along the depth gradient indicated that PAH pollution was stabilized since the early 1990s while the source of PAHs has gradually changed from combustion of coal to petroleum products. This implied that the mitigation measures taken by the Chinese government were effective. Compared to marine bottom sediment, we propose that using mangrove sediment can provide a more accurate and precise estimate of pollution history of PAHs. PMID:24981104

Wu, Qihang; Leung, Jonathan Y S; Tam, Nora F Y; Chen, Shejun; Mai, Bixian; Zhou, Xizhen; Xia, Lihua; Geng, Xinhua

2014-08-15

234

Coal-tar pavement sealants might substantially increase children's PAH exposures  

USGS Publications Warehouse

Dietary ingestion has been identified repeatedly as the primary route of human exposure to polycyclic aromatic hydrocarbons (PAHs), seven of which are classified as probable human carcinogens (B2 PAHs) by the U.S. EPA. Humans are exposed to PAHs through ingestion of cooked and uncooked foods, incidental ingestion of soil and dust, inhalation of ambient air, and absorption through skin. Although PAH sources are ubiquitous in the environment, one recently identified PAH source stands out: Coal-tar-based pavement sealant—a product applied to many parking lots, driveways, and even playgrounds primarily in the central, southern, and eastern U.S.—has PAH concentrations 100–1000 times greater than most other PAH sources. It was reported recently that PAH concentrations in house dust in residences adjacent to parking lots with coal-tar-based sealant were 25 times higher than in residences adjacent to unsealed asphalt parking lots.

Williams, E. Spencer; Mahler, Barbara J.; Van Metre, Peter C.

2012-01-01

235

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...

236

Metabolism of mixtures of polycyclic aromatic hydrocarbons (PAHs) by Cunninghamella elegans  

E-print Network

Polycyclic aromatic hydrocarbons (PAHs) are environmentally significant compounds due to the toxicity of some members. They are ubiquitous and are persistent bioaccumulative toxins(PBTs). The toxicity of PAHs represents a risk to human health...

Olatubi, Oluwaseun Alfred

2007-04-25

237

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

238

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 3500 ng m(-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 (2-23 ng m(-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

239

Optical Spectroscopy of Radiation Processed Cosmic Ices & PAH-doped Water-rich Ices  

NASA Astrophysics Data System (ADS)

Water-rich, mixed molecular ices and polycyclic aromatic hydrocarbons (PAHs) are common throughout interstellar molecular clouds and the Solar System. Vacuum ultraviolet (VUV) irradiation and particle bombardment of these abiotic ices produces complex organic species, including important biogenic molecules such as amino acids and functionalized PAHs. This ability of such water-rich, oxygen-dominated ices to promote production of complex organic species is important. We will present studies on cosmic ices that include PAH-impurities upon vacuum ultraviolet (VUV) irradiation using electronic spectroscopy. VUV-irradiation of PAH / H2O ices leads to efficient conversion of the neutral PAHs to their cation form (PAH+). Further, these H2O / PAH+ ices are stable at temperatures below 50 K, a temperature domain common throughout interstellar clouds and the Solar System. In view of this, we conclude that charged PAHs and other molecular ions should be common and abundant in many cosmic ices.

Gudipati, Murthy S.; Allamandola, Louis J.

240

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...

241

ASSESSING THE POTENTIAL FOR PHOTO-ACTIVATED TOXICITY OF PAHS IN AQUATIC SYSTEMS  

EPA Science Inventory

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants introduced through combustion processes and from release of petroleum and petroleum products. Assessing the ecological risk from PAHs is complicated by several factors, including their occurrence a...

242

PAH-DNA adducts in a Chinese population: relationship to PAH exposure, smoking and polymorphisms of metabolic and DNA repair genes.  

PubMed

The present study was conducted in a Chinese population to evaluate the usefulness and sensitivity of PAH-DNA adduct as a biomarker of PAH exposure, and to examine the potential effects of smoking and polymorphisms of responsive genes on DNA adduct formation induced by PAH exposure. The polymorphisms of genes examined include GSTM1, GSTT1, CYP1A1, microsomal epoxide hydrolase (mEH) and excision repair cross-complementary group 2 (ERCC2). A total of 194 subjects with a broad range of PAH exposures were recruited, including 116 occupationally exposed workers, 49 metropolitan residents and 29 suburban gardeners. A significant exposure-response relationship was observed between PAH exposure and DNA adducts in leukocytes across the entire group of subjects (p < 0.0001). The levels of PAH-DNA adducts in the subgroup with lowest occupational exposure to PAHs (< 0.1 microg BaP m(-3)) was significantly higher than that in metropolitan residents and suburban gardeners. However, no significant difference was detected between residents and gardeners, with mean BaP concentrations of 0.028 and 0.011 microg m(-3), respectively. The polymorphisms of genes examined failed to show significant effects on PAH-induced adduct formation except ERCC2 Lys751Gln genotypes. A significantly higher level of PAH-DNA adduct was found in subjects with wild-type ERCC2 than those who have either heterozygous or homozygous variant alleles (p < 0.01). Smoking, age and gender did not substantially contribute to PAH-induced DNA adduct formation in this study. The study suggests that PAH-DNA adducts may serve as a reliable biomarker of PAH exposure in occupational settings but may not be sensitive enough to be used in populations with environmental exposures to PAHs. PMID:17896209

Hu, Yu; Li, Gang; Xue, Xiaonan; Zhou, Zongcan; Li, Xiaomei; Fu, Juanling; Cohen, Beverly; Roy, Nirmal; Li, Donghui; Sun, Jianya; Nan, Peihong; Tang, Moon-Shong; Qu, Qingshan

2008-02-01

243

Bioremediation of PAHs-contaminated soil through composting: Influence of bioaugmentation and biostimulation on contaminant biodegradation  

Microsoft Academic Search

The degradation of several polycyclic aromatic hydrocarbons (PAHs) in soil through composting was investigated. The selected PAHs included: fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene, and chrysene, with concentrations simulating a real creosote sample. The degradation of PAHs (initial concentration 1 g of total PAHs kg?1 dry soil) was assessed applying bioaugmentation with the white-rot fungi Trametes versicolor and biostimulation using compost

Tahseen Sayara; Eduard Borràs; Gloria Caminal; Montserrat Sarrà; Antoni Sánchez

2011-01-01

244

Far-infrared emission spectra of selected gas-phase PAHs: Spectroscopic fingerprints  

SciTech Connect

The emission spectra of the gaseous polycyclic aromatic hydrocarbons (PAHs) naphthalene, chrysene, and pyrene were recorded in the far-infrared (far-IR) region. The vibrational bands that lie in the far IR are unique for each PAH molecule and allow discrimination among the three PAH molecules. The far-IR PAH spectra, therefore, may prove useful in the assignment of unidentified spectral features from astronomical objects. 23 refs., 1 fig., 1 tab.

Zhang, K.; Guo, B.; Colarusso, P.; Bernath, P.F. [Univ. of Waterloo, Ontario (Canada)] [Univ. of Waterloo, Ontario (Canada)

1996-10-25

245

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

246

Assessment of PAH Levels in Atmospheric Particulates from  

E-print Network

________________________________________________________60 #12;3 ABSTRACT PAHs were assessed in dry air at Burnaby Lake, located in the greater Vancouver Instruments _________________________________________________ 6 1.1.2 High Volume/Poly-Urethane Foam Sampler and deposition rates to an urban watershed. Weekly samples were collected using a high volume polyurethane foam

247

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

248

Levels, trends and health concerns of atmospheric PAHs in Europe  

NASA Astrophysics Data System (ADS)

Changes in climate can affect the concentration patterns of polycyclic aromatic hydrocarbons (PAHs) by altering the dispersion (wind speed, mixing layer height, convective fronts), deposition by precipitation, dry deposition, photochemistry, natural emissions and background concentrations. This means the evolution trends of these pollutants have to be studied under a multi-scale perspective, allowing the establishment of transport patterns and distribution of PAHs. In this sense, this work tries to unveil the atmospheric behaviour of these pollutants using temporal data series collected in different stations from the European Monitoring and Evaluation Programme (EMEP) air sampling network. These sites are thought to avoid the direct influence of emitting areas (background stations), allowing the study of long-range transport effects, intra- and trans-annual variability, relationships between concentrations patterns and meteorological variables and latitudinal gradients of PAH levels in Europe. Overall, a typical high concentration pattern was found for the colder months (and an opposite behaviour is found for summertime). Negative trends were detected over high latitudes, for instance, in Svalbard (Norway), whereas for the United Kingdom the pattern is the inverse. Also, negative latitudinal gradients were observed in 4 of the 15 PAHs studied. Finally, air quality parameters revealed concern over human health issues, given the recent increase of BaP levels in Europe.

Garrido, Adrián; Jiménez-Guerrero, Pedro; Ratola, Nuno

2014-12-01

249

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...

250

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

251

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...

252

PAH Degradation and Bioaugmentation by a Marine Methanotrophic Enrichment  

Microsoft Academic Search

Methanotrophic bacteria were enriched from marine sediments and screened for their ability to biotransform polycyclic aromatic hydrocarbons (PAHs). Characterization of the methanotrophic enrichment showed that it was dominated by a Type I methanotroph, although significant amounts of 18:1 fatty acids were detected, suggesting the presence of Type II methanotrophs in marine systems. The methanotrophic enrichment degraded phenanthrene, anthracene, and fluorene

Karl J. Rockne; H. David Stensel; Russell P. Herwig; Stuart E. Strand

1998-01-01

253

AN OVERVIEW OF PARTITIONING AND BIOAVAILABILITY OF PAHS IN SEDIMENTS AND SOILS  

EPA Science Inventory

Understanding and predicting any adverse effects of PAHs depends on generating a reliable measure or estimate of how much PAH is available for uptake. Simply knowing the total amount of PAH in soil, water or sediment is insufficient for determining whether or not these compounds ...

254

Natural attenuation of PAHs under anaerobic conditions C.Rollin (V, T. Heidi2  

E-print Network

(surface and pores). The adaptation of the microflora to the degradation of the PAH under sulfate reducing of the PAH concentrations occurred. During the last period (100* to 248th day : phase 3) degradation of allNatural attenuation of PAHs under anaerobic conditions C.Rollin (V, T. Heidi2 ), J. Laversanne (V

Paris-Sud XI, Université de

255

Removal of polycyclic aromatic hydrocarbons (PAHs) from sewage sludge by anaerobic degradation  

E-print Network

Removal of polycyclic aromatic hydrocarbons (PAHs) from sewage sludge by anaerobic degradation N, terminate in the sludge, and can be released to the environment if land spreading is used. PAH degradation factors of anaerobic PAH degradation by evaluating thermodynamic feasibility of degradation, assessing

256

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

257

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

258

Comparison of a bioremediation process of PAHs in a PAH-contaminated soil at field and laboratory scales  

Microsoft Academic Search

A laboratory experiment was carried on the same initial soil and at the same time than a windrow treatment in order to compare results at field and laboratory scales for a soil mainly contaminated with PAHs. After 6 months, laboratory experiments gave similar but less scattered results than those obtained in the field indicating that the field biotreatment was well

C. Lors; D. Damidot; J. F. Ponge; F. Périé

2012-01-01

259

Desorption of selected PAHs as individuals and as a ternary PAH mixture within a water-soil-nonionic surfactant system  

Microsoft Academic Search

Remediation of soil contaminated with polycyclic aromatic hydrocarbons (PAHs) is a major environmental concern due to the toxic and carcinogenic properties of these compounds. Desorption and partitioning of anthracene, fluorene and pyrene within soil–aqueous systems in the presence of the nonionic surfactants, Triton X-100 and Tween 80,were studied. The results showed that the addition of Tween 80 solution at 10

Taghreed A. Hussein; Zainab Z. Ismail

2012-01-01

260

Diagnostic Immunopathology  

PubMed Central

The application of immunologic techniques to tissue sections has added a new dimension to the investigation and classification of various processes. Virtually every section of diagnostic pathology has been enhanced by using specific monoclonal antibodies or polyclonal antiserum. Neoplasms formerly diagnosed as poorly differentiated or anaplastic may be precisely identified as to their origin through the use of specific membrane or cytoplasmic markers. Other cellular products, including viruses, hormones, enzymes or highly specific proteins, are also available to study neoplastic and nonneoplastic processes. New and more specific reagents are regularly becoming available for the diagnostic repertoire of pathologists. We present some of the principles of diagnostic immunopathology to show the scope and importance of the techniques. ImagesFigure 2.Figure 3. PMID:3529633

Cancilla, Pasquale A.; Cochran, Alistair J.; Naeim, Faramarz; Said, Jonathan W.

1986-01-01

261

Biological and abiotic losses of polynuclear aromatic hydrocarbons (PAHs) from soils freshly amended with sewage sludge  

SciTech Connect

Sewage sludge containing typical indigenous concentrations of polynuclear aromatic hydrocarbons (PAHs) was applied to several different soils in glass microcosms. Biologically active and sterilized soils were monitored for PAH content over a period of approximately 205 d. Agricultural soils with and without previous exposure to sewage sludge were tested, together with a forest soil and a soil from a major roadside. Loss of PAHs from a soil spike with a PAH standard solution was also investigated. Results indicate the PAH compounds with less than four benzene rings are susceptible to abiotic loss processes. However, losses by these mechanisms were insignificant for compounds with four or more benzene rings. Half-lives for the sludge-applied PAHs were derived and indicated a strong dependence of persistence on chemical structure. Half-lives for phenanthrene and benzo[ghi]perylene were between 83 and 193 d and 282 and 535 d, respectively. Mean half-lives correlate directly with log K[sub ow] and inversely with log water solubility. Behavior of PAHs was different in each soil, probably due to different soil characteristics and history of PAH exposure. The soil spiked with PAHs provided the lowest half-life values for most PAH compounds, suggesting a higher susceptibility of spiked PAHs to both abiotic and biological degradation.

Wild, S.R.; Jones, K.C. (Lancaster Univ. (United Kingdom))

1993-01-01

262

Pah Transport In The Unsaturated Zone At A Manufactured Gas Plant (mgp) Site  

NASA Astrophysics Data System (ADS)

The transport of polyaromatic hydrocarbons in the unsaturated zone at contaminated sites is governed by the interplay of different transport mechanisms: The most promi- nent are advective-dispersive and diffusive fluxes with water and non-aqueous phase liquids in the dissolved phase, and the carrier assisted transport with colloids and par- ticles. The driving gradients are gravity and, most important, the amount, the intensity and the spatio-temporal distribution of precipitation. In order to identify the govern- ing transport pathways as a function of the meteorological conditions, we studied the release and redistribution of PAHs at a former manufactured gas plant (MGP) site. We installed four field lysimeters to monitor the seepage water. Two lysimeters were located at the field site and two others - refilled with site material- were translocated and installed in a region with different meteorological conditions. After filtration, the seepage water was analysed for dissolved PAHs and the retentate, which resembles the particulate and colloidal fraction, was analysed for PAH, also. The PAH-pattern of the retentate was in high accordance to the soil PAH pattern. High molecular weigth PAH amount to 55 %, while low molecular weight PAH reach 45 %. In contrast, the amount of high molecular weight PAH in the filtrate amounts only to 40%. The con- centration of single PAH in the filtrate was found to be far below the water solubility. Thus, PAH dissolution is of minor importance for the release and transport, while particulate and colloid related PAH transport dominates the fate of PAH in the unsatu- rated zone. The meteorological characteristic of the original field site shows short and strong precipitation events during summer time which lead to surface runoff. Seepage and consequently PAH transport does not occur during this period. In contrast, higher total precicpitation and the different distribution pattern at the other site results in higher moisture contents over longer time and thus leads to PAH seepage throughout the year.

Hensel, D.; Totsche, K. U.; Kögel-Knabner, I.

263

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. PMID:23484001

Gao, Yanzheng; Long, Jian; Wang, Qian

2013-01-01

264

Phototoxicity and Environmental Transformation of Polycyclic Aromatic Hydrocarbons (PAHs)—Light-Induced Reactive Oxygen Species, Lipid Peroxidation, and DNA Damage  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs) are a class of mutagenic and tumorigenic environmental contaminants. Although the mechanisms by which PAHs induce cancer in experimental animals have been extensively studied and the metabolic activation pathways have been determined, the environmental fate of PAHs and the phototoxicity exerted by PAHs, as well as their photoreaction products formed in the environment, have received much

Peter P. Fu; Qingsu Xia; Xin Sun; Hongtao Yu

2012-01-01

265

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

266

Distribution of PAHs and the PAH-degrading bacteria in the deep-sea sediments of the high-latitude Arctic Ocean  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants, which can be transferred to a long distance and tend to accumulation in marine sediment. However, PAHs distribution and natural bioattenuation is less known in open sea, especially in the Arctic Ocean. In this report, sediment samples were collected at four sites from the Chukchi Plateau to Makarov Basin in the summer of 2010. PAH composition and total concentrations were examined with GC-MS, we found that the concentrations of 16 EPA-priority PAHs varied from 2.0 to 41.6 ng g-1 dry weight in total and decreased with sediment depths and as well as from the southern to northern sites. Among the targeted PAHs, phenanthrene was relatively abundant in all sediments. To learn the diversity of bacteria involved in PAHs degradation in situ, the 16S rRNA gene of the total environmental DNA was analyzed with Illumina high throughput sequencing (IHTS). In all the sediments, occurred the potential degraders including Cycloclasticus, Pseudomonas, Halomonas, Pseudoalteromonas, Marinomonas, Bacillus, Dietzia, Colwellia, Acinetobacter, Alcanivorax, Salinisphaera and Shewanella, with Dietzia as the most abundant. Meanwhile on board, enrichment with PAHs was initiated and repeated transfer in laboratory to obtain the degrading consortia. Most above mentioned bacteria in addition to Hahella, Oleispira, Oceanobacter and Hyphomonas, occurred alternately as a predominant member in enrichment cultures from different sediments, as revealed with IHTS and PCR-DGGE. To reconfirm their role in PAH degradation, 40 different bacteria were isolated and characterized, among which Cycloclasticus and Pseudomonas showed the best degradation capability under low temperature. Taken together, PAHs and PAH-degrading bacteria were widespread in the deep-sea sediments of the Arctic Ocean. We propose that bacteria of Cycloclasticus, Pseudomonas, Pseudoalteromonas, Halomonas, Marinomonas and Dietzia may play the most important role in PAHs mineralization in situ.

Dong, C.; Bai, X.; Sheng, H.; Jiao, L.; Zhou, H.; Shao, Z.

2014-09-01

267

Diagnostic imaging.  

PubMed

Physical techniques have always had a key role in medicine, and the second half of the 20th century in particular saw a revolution in medical diagnostic techniques with the development of key imaging instruments: x-ray imaging and emission tomography (nuclear imaging and PET), MRI, and ultrasound. These techniques use the full width of the electromagnetic spectrum, from gamma rays to radio waves, and sound. In most cases, the development of a medical imaging device was opportunistic; many scientists in physics laboratories were experimenting with simple x-ray images within the first year of the discovery of such rays, the development of the cyclotron and later nuclear reactors created the opportunity for nuclear medicine, and one of the co-inventors of MRI was initially attempting to develop an alternative to x-ray diffraction for the analysis of crystal structures. What all these techniques have in common is the brilliant insight of a few pioneering physical scientists and engineers who had the tenacity to develop their inventions, followed by a series of technical innovations that enabled the full diagnostic potential of these instruments to be realised. In this report, we focus on the key part played by these scientists and engineers and the new imaging instruments and diagnostic procedures that they developed. By bringing the key developments and applications together we hope to show the true legacy of physics and engineering in diagnostic medicine. PMID:22516558

Morris, Peter; Perkins, Alan

2012-04-21

268

Diagnostic Systems  

Microsoft Academic Search

\\u000a Diagnosis and epidemiology are core topics in psychiatry and developmental medicine. There can be no clinical medical work\\u000a without diagnosis. There can be no medical epidemiological study of psychiatric disorder without a consideration of diagnostic\\u000a boundaries.

Christopher L. Gillberg

269

Reduction of Ferrrihydrite and Akaganeite by Shewanella alga (PAH93)  

NASA Astrophysics Data System (ADS)

Shewanella species are capable of oxidizing diverse organic acids coupled to reducing Fe(III) (oxy)hydroxides to crystalline Fe(II)-containing phases such as magnetite, siderite, and vivianite. The objective of this study was to examine reduction of ferrihydrite and akaganeite as the electron acceptors using various organic acids as the electron donors by Shewanella alga (PAH93) isolated from Yeosu, South Korea. Microbial reduction of akaganeite (40 mM) and ferrihydrite (40 mM) was examined using acetate (10 mM), glucose (10 mM), and lactate (10 mM) as electron donors at room temperature. Ferrozine method was used to analyze both water soluble and HCl soluble Fe(II) concentrations during the microbial Fe(III) reduction. XRD and TEM-EDX analyses were used to characterize biominerals formed by PAH93. PAH93 was completely reduced ferrihydrite to Fe(II), which transformed as siderite (FeCO3). PAH93 was oxidized acetate, glucose, and lactate coupled to reducing akaganeite to magnetite or green rust. Microbial reduction of ferrihydrite resulted in higher soluble Fe(II) concentration (446 - 498 mg/L) than the reduction of akaganeite (255 - 284 mg/L) within 6 days of incubation. For 21 days of incubation, souble Fe(II) concentration during akaganeite reduction (945 - 1316 mg/L) was higher than ferrihydrite reduction (120 - 738 mg/L). It may be attributed to the differences of crystallinity of the iron minerals used for microbial iron reduction. This study indicates types of the electron acceptors, ferrihydrite and akaganeite, affect Fe(II) reduction rate and types of the biotransformed minerals.

Jung, M.; Kim, Y.; Lee, Y.; Kwon, K.; Roh, Y.

2009-12-01

270

Prediction of PAH mutagenicity in human cells by QSAR classification.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants of high environmental concern. The experimental data of a mutagenicity test on human B-lymphoblastoid cells (alternative to the Ames bacterial test) for a set of 70 oxo-, nitro- and unsubstituted PAHs, detected in particulate matter (PM), were modelled by Quantitative Structure-Activity Relationships (QSAR) classification methods (k-NN, k-Nearest Neighbour, and CART, Classification and Regression Tree) based on different theoretical molecular descriptors selected by Genetic Algorithms. The best models were validated for predictivity both externally and internally. For external validation, Self Organizing Maps (SOM) were applied to split the original data set. The best models, developed on the training set alone, show good predictive performance also on the prediction set chemicals (sensitivity 69.2-87.1%, specificity 62.5-87.5%). The classification of PAHs according to their mutagenicity, based only on a few theoretical molecular descriptors, allows a preliminary assessment of the human health risk, and the prioritisation of these compounds. PMID:18311639

Papa, E; Pilutti, P; Gramatica, P

2008-01-01

271

Two fish bile reference materials certified for PAH metabolites.  

PubMed

Environmental pollution with polycyclic aromatic hydrocarbons (PAHs) from pyrogenic or petrochemical sources is a matter of concern in many aquatic ecosystems. For field monitoring purposes, PAH metabolite levels in fish bile samples can be used as biomarkers of exposure, but previously there were no reference materials for analytical method validation or quality control. In this paper we describe the preparation and certification of two fish bile materials. BCR 720 is a pure bile material from sediment-exposed flounder (Platichthys flesus) and BCR 721 is a pure bile material from oil-exposed plaice (Pleuronectes platessa). Homogeneity and stability tests were carried out and a group of 12 expert laboratories was assembled for the certification measurements. The methods applied were liquid chromatography with fluorescence detection or gas chromatography with mass spectrometric detection. In BCR 720 three PAH metabolites were certified: 1-hydroxyphenanthrene, 1-hydroxypyrene and 3-hydroxybenzo[a]pyrene. In BCR 721 1-hydroxypyrene was certified. The fourth target compound, 2-hydroxynaphthalene, could not be certified, but the results obtained are listed. The major findings from earlier feasibility studies and recommendations for the optimal use of the reference materials are also included. PMID:16121266

Ariese, Freek; Beyer, Jonny; Wells, David

2005-09-01

272

Polycyclic aromatic hydrocarbons (PAHs) biodegradation in the soil of a former gasworks site: selection and study of PAHs-degrading microorganisms  

Microsoft Academic Search

Natural PAHs biodegradation was shown in the soil of a former gasworks site and the influence on biodegradation efficiency of sawdust addition studied. Cultures enriched by serial transfer through a mineral medium containing either fluorene, phenanthrene, anthracene, fluoranthene, or pyrene were used to obtain several bacterial communities. The obtained consortia were able to grow on different individual PAHs as their

C Bidaud; C Tran-Minh

1998-01-01

273

PAH Mutation Analysis Consortium Database: a database for disease-producing and other allelic variation at the human PAH locus.  

PubMed Central

The PAH Mutation Analysis Consortium (81 investigators, 26 countries) is engaged in mutation detection at the human PAH locus. Ascertainment of probands occurs largely through newborn screening for hyperphenylalaninemia. A relational database records allelic variation (disease-producing and polymorphic) at the locus. Information is distributed by Newsletter, diskette (WINPAHDB software stand-alone executable on IBM compatible hardware), and at a 'real' site on the Worldwide Web (http://www.mcgill.ca/pahdb). The database presently records (Sept. 27, 1995) 248 alleles in 798 different associations (with polymorphic haplotype, geographic region and population) along with additional information. The database, as a record of human genetic diversity, at a particular locus, contributes to the study of human evolution and demic expansion; it also has medical relevance. PMID:8594560

Hoang, L; Byck, S; Prevost, L; Scriver, C R

1996-01-01

274

Using slow-release permanganate candles to remediate PAH-contaminated water.  

PubMed

Surface waters impacted by urban runoff in metropolitan areas are becoming increasingly contaminated with polycyclic aromatic hydrocarbons (PAHs). Slow-release oxidant candles (paraffin-KMnO(4)) are a relatively new technology being used to treat contaminated groundwater and could potentially be used to treat urban runoff. Given that these candles only release permanganate when submerged, the ephemeral nature of runoff events would influence when the permanganate is released for treating PAHs. Our objective was to determine if slow-release permanganate candles could be used to degrade and mineralize PAHs. Batch experiments quantified PAH degradation rates in the presence of the oxidant candles. Results showed most of the 16 PAHs tested were degraded within 2-4 h. Using (14)C-labled phenanthrene and benzo(a)pyrene, we demonstrated that the wax matrix of the candle initially adsorbs the PAH, but then releases the PAH back into solution as transformed, more water soluble products. While permanganate was unable to mineralize the PAHs (i.e., convert to CO(2)), we found that the permanganate-treated PAHs were much more biodegradable in soil microcosms. To test the concept of using candles to treat PAHs in multiple runoff events, we used a flow-through system where urban runoff water was pumped over a miniature candle in repetitive wet-dry, 24-h cycles. Results showed that the candle was robust in removing PAHs by repeatedly releasing permanganate and degrading the PAHs. These results provide proof-of-concept that permanganate candles could potentially provide a low-cost, low-maintenance approach to remediating PAH-contaminated water. PMID:23089061

Rauscher, Lindy; Sakulthaew, Chainarong; Comfort, Steve

2012-11-30

275

Concentrations of heavy metals (Cu, Cd, Zn and Ni) and PAHs in Perna viridis collected from seaport and non-seaport waters in the Straits of Johore.  

PubMed

In this study, the ranges of pollutants found in the soft tissues of Perna viridis collected from Kg. Masai and Kg. Sg. Melayu, both located in the Straits of Johore, were 0.85-1.58 ?g/g dry weight (dw) for Cd, 5.52-12.2 ?g/g dw for Cu, 5.66-8.93 ?g/g dw for Ni and 63.4-72.3 ?g/g dw for Zn, and 36.4-244 ng/g dry weight for ?PAHs. Significantly (p < 0.05) higher concentrations of Cd, Cu, Ni, Zn and ?PAHs in the mussels were found in the water of a seaport site at Kg. Masai than a non-seaport site at Kg. Sg. Melayu population. The ratios of low molecular weight/high molecular weight hydrocarbons (2.94-3.42) and fluoranthene/pyrene (0.43-0.45) in mussels from both sites indicated the origin of the PAHs to be mainly petrogenic. This study has demonstrated the utility of using the soft tissues of P. viridis as a biomonitor of PAH contamination and bioavailability in the coastal waters of Peninsular Malaysia. PMID:23052577

Yap, C K; Shahbazi, A; Zakaria, M P

2012-12-01

276

Paper Diagnostics  

NSDL National Science Digital Library

This lesson, presented by the National Nanotechnology Infrastructure Network, focuses on diagnostic methods of investigation looking at the issue of HIV/AIDS. In this activity, students will explore "the societal impacts of engineering and science, specifically as it relates to the AIDS epidemic in developing countries. A series of videos and accompanying questions help students explore how engineers and scientists can contribute to various solutions related to diagnosing and preventing the spread of disease. The activity highlights the development of low-cost paper diagnostics for rapid and private diagnosis of AIDS and diseases  related to AIDS (TB, other sexually transmitted diseases, etc.)." This activity will take two 50 minute classroom sessions. A Teacher Preparation Guide, Next Generation Science Standards for this lesson, and a link to George Whitesides video used in lesson video from the NY Times are included.

2014-08-12

277

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

278

Diagnostic immunofluorescence*  

PubMed Central

The standardization of diagnostic immunofluorescence is a complex problem because diagnostic results are greatly influenced by interacting factors, such as the equipment, materials, and techniques for expressing and recording fluorescence. Furthermore, the characteristics of immunofluorescence reagents depend on how they are manufactured and used. The adoption of stable reference preparations of such reagents appears to be the only practicable way of standardizing laboratory test results. Several professional and regulatory organizations are actively promoting this objective. Consensus evaluation may be the best method of introducing proposed standards. Basic and applied research must provide the information needed to improve reagents and tests. Material fluorescent standards are proving helpful in standardizing fluorescence emission, but the most promising development is the use of insolubilized antigens to provide standards for more relevant immunological-fluorescence comparisons. Several important direct and indirect diagnostic immunofluorescence tests and reagents currently used in microbiological, histological, and pathological examinations require standardization. The medical profession should insist that commercial reagents be adequately characterized and that manufacturers supply the data necessary for their safe and informed use. PMID:4594319

Cherry, William B.; Reimer, Charles B.

1973-01-01

279

AKARI infrared camera observations of the 3.3 ?m PAH feature in Swift/BAT AGNs  

NASA Astrophysics Data System (ADS)

We explore the relationships between the 3.3 ?m polycyclic aromatic hydrocarbon (PAH) feature and active galactic nucleus (AGN) properties of a sample of 54 hard X-ray selected bright AGNs, including both Seyfert 1 and Seyfert 2 type objects, using the InfraRed Camera (IRC) on board the infrared astronomical satellite AKARI. The sample is selected from the nine-month Swift/BAT survey in the 14-195 keV band and all of them have measured X-ray spectra at E ? 10 keV. These X-ray spectra provide measurements of the neutral hydrogen column density (NH) towards the AGNs. We use the 3.3 ?m PAH luminosity (L3.3?m) as a proxy for star-formation activity and hard X-ray luminosity (L14-195 keV) as an indicator of the AGN activity. We search for possible differences in star-formation activity between type 1 (unabsorbed) and type 2 (absorbed) AGNs. We have made several statistical analyses taking the upper limits of the PAH lines into account utilizing survival analysis methods. The results of our log (L14-195 keV) versus log (L3.3 ?m) regression show a positive correlation and the slope for the type 1/unobscured AGNs is steeper than that of type 2/obscured AGNs at a 3 ? level. Our analysis also shows that the circumnuclear star formation is more enhanced in type 2/absorbed AGNs than type 1/unabsorbed AGNs for low X-ray luminosity/low Eddington ratio AGNs, while there is no significant dependence of star-formation activities on the AGN type in the high X-ray luminosities/Eddington ratios.

Castro, Angel; Miyaji, Takamitsu; Shirahata, Mai; Ichikawa, Kohei; Oyabu, Shinki; Clark, David M.; Imanishi, Masatoshi; Nakagawa, Takao; Ueda, Yoshihiro

2014-11-01

280

Laboratory and Ambient Studies of the Products of Gas-Phase Hydroxyl and Nitrate Ion Radical-Initiated Reactions with Selected PAHs  

NASA Astrophysics Data System (ADS)

Nitrated polycyclic aromatic hydrocarbon (nitro-PAH) product distributions from the gas-phase hydroxyl (OH) and nitrate (NO3) radical-initiated reactions with selected PAHs, as well as the heterogeneous reactions of surface-bound PAHs with N2O5 and HNO3, were investigated. Chapter 2 presents formation yields of nitro-PAHs from the gas-phase OH radical-initiated reactions of 1,7- and 2,7-dimethylnaphthalene (DMN) as a function of NO 2 concentration over the range 0.04-0.14 ppmv. The measured formation yields of dimethylnitronaphthalenes (DMNNs) under conditions that the OH-DMN adducts reacted solely with NO2 were 0.252 ± 0.094% for ?1,7-DMNNs and 0.010 ± 0.005% for ?2,7-DMNNs. 1,7-dimethyl-5-nitronaphthalene (1,7DM5NN) was the major nitro-isomer formed, with a limiting high-NO 2 concentration yield of 0.212 ± 0.080% and with equal reactions of the 1,7-DMN-OH adduct with NO2 and O2 occurring in air at 60 ± 39 ppbv of NO2, indicating that the OH-DMN adduct reaction with NO2 can be important at NO2 concentrations commonly found in urban atmospheres. Although the yields of the DMNNs are low, ?0.3%, the DMNN (and ethylnitronaphthalene) profiles from chamber experiments match well with those observed in polluted urban areas under conditions where OH radical-initiated chemistry is dominant, such as Mexico City, Mexico. Chapter 3 examines the nitro-PAH products of gas-phase OH and NO 3 radicals and heterogeneous N2O5 reactions with fluoranthene, pyrene, benz[a]anthracene, chrysene, and triphenylene. Analysis of nitro-PAHs in the NIST diesel particulate SRM (1975) and selected ambient samples are also presented. 2-Nitrofluoranthene (2-NFL) was the most abundant nitro-PAH in Riverside, CA and Mexico City, and the mw 273 nitro-PAHs were observed in lower concentrations. However, in Tokyo, Japan, concentrations of 1- + 2-nitrotriphenylene (NTP) were more similar to those of 2-NFL. Comparing specific nitro-PAH ratios in ambient particulate samples from Tokyo, Mexico City, and Riverside, and in diesel particles with those from chamber experiments confirms the atmospheric formation of 2-NFL and 2-nitropyrene (2-NPY) via gas-phase radical-initiated reactions. Heterogeneous nitration of ambient particle-bound PAHs is investigated in Chapter 4. Ambient particulate samples collected in Beijing, China, and from four sites within the Los Angeles air basin (Los Angeles, Azusa, Riverside, and Banning), along with filter-bound deuterated PAHs, were exposed to a gas-phase equilibrium mixture of N2O5, NO3 radicals, and NO2 in an environmental chamber at ambient pressure and temperature. For the majority of these reactions 1-nitropyrene was the nitro-PAH formed in the greatest amount and was determined to occur heterogeneously (and not in the gas-phase) by using isomer distribution patterns of deuterated nitro-PAHs either formed on filter surfaces or collected from the chamber in the gas-phase. Chapter 5 investigates the contributions of atmospheric formation (OH versus NO3 chemistry) and direct emissions (electrophilic nitration products) to ambient gas-phase and particulate nitro-PAHs sampled in the Los Angeles air basin and Mexico City, Mexico, over several sampling campaigns using a combination of several marker ratios of volatile and semi-volatile nitro-PAHs. Ratios of 2-nitrofluoranthene (2-NFL)/2-nitropyrene (2-NPY), 2-methyl-4-nitronaphthalene (2M4NN)/1-methyl-5-nitronaphthalene (1M5NN), and 2,7-dimethyl-4-nitronaphthalene (2,7DM4NN)/1,7-dimethyl-5-nitronaphthalene (1,7DM5NN) were used to assess the contribution of OH radical chemistry versus NO3 radical chemistry to ambient nitro-PAHs from 50 particle-phase and gas-phase samples. (Abstract shortened by UMI.).

Zimmermann, Kathryn Jean

281

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

282

Impact of soil amendments and the plant rhizosphere on PAH behaviour in soil.  

PubMed

Carbonaceous amendments reduce PAH dissolved concentrations (Cfree), limiting their uptake and toxicity. A soil contaminated with PAHs was mixed with activated carbon (AC), charcoal or compost and planted with radish (Raphanus sativus L.), and Cfree, chemical activities and diffusive uptake of the PAHs measured over 2 months. For AC, Cfree and diffusive uptake were decreased by up to 94% compared to the unamended soil within one week. In addition, the sum chemical activity of the PAHs remained below the threshold for baseline toxicity. In contrast, charcoal and compost only led to modest reductions in Cfree and diffusive uptake, with sum chemical activities that could potentially result in baseline toxicity being observed. Furthermore, both Cfree and diffusive uptake were lower in the planted compared to unplanted soils. Therefore, only AC successfully reduced PAH acute toxicity in the soil, but plant-promoted microbial degradation may also play an important role in PAH attenuation. PMID:24583710

Marchal, Geoffrey; Smith, Kilian E C; Mayer, Philipp; Wollesen de Jonge, Lis; Karlson, Ulrich G

2014-05-01

283

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

284

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

285

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. PMID:23527124

Liao, Chun-Hou; Kuo, Hann-Chorng

2013-01-01

286

PAH source fingerprints for coke ovens, diesel and, gasoline engines, highway tunnels, and wood combustion emissions  

Microsoft Academic Search

To evaluate the chemical composition (source fingerprint) of the major sources of polyaromatic hydrocarbons (PAHs) in the Chicago metropolitan area, a study of major PAH sources was conducted during 1990–1992. In this study, a modified high-volume sampling method (PS-1 sampler) was employed to collect airborne PAHs in both the particulate and gas phases. Hewlett Packard 5890 gas chromatographs equipped with

Nasrin R. Khalili; Peter A. Scheff; Thomas M. Holsen

1995-01-01

287

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

288

Pilot study: PAH fingerprints of aircraft exhaust in comparison with diesel engine exhaust  

Microsoft Academic Search

In the course of a preliminary investigation the PAH fingerprints from diesel engines were compared with those from aircraft\\u000a turbines. The goal was to determine whether PAH fingerprints permit to distinguish between the sources of air and road traffic.\\u000a The results showed that the PAH spectra of both sources do not vary significantly. However, in turbine exhaust gas p-quaterphenyl\\u000a was

J. Krahl; H. Seidel; H.-E. Jeberien; M. Rückert; M. Bahadir

1998-01-01

289

Kinetics of Polycyclic Aromatic Hydrocarbon (PAH) Degradation in Long-term Polluted Soils during Bioremediation  

Microsoft Academic Search

Bioremediation experiments with ten different soil samples from former industrial sites which were long-term polluted with\\u000a polycyclic aromatic hydrocarbons (PAHs) were carried out using outdoor pot trials. The degradation of 15 PAHs according to\\u000a the US EPA was investigated for 168 weeks through repeated soil sampling and determination of the total PAH concentration.\\u000a On average, degradation was largest for acenaphthene

S. Thiele-Bruhn; G. W. Brümmer

2005-01-01

290

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

291

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

292

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

293

Catalysis of PAH Biodegradation by Humic Acid Shown in Synchrotron Infrared Studies  

E-print Network

, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 5 Center for Biofilm Engineering, Montana State increasing the PAH bioavailability to microorganisms. Despite abundant evidence that HA is important

294

The investigation of reducing PAHs emission from coal pyrolysis by gaseous catalytic cracking.  

PubMed

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. PMID:24963507

Wang, Yulong; Zhao, Ruifang; Zhang, Chun; Li, Guanlong; Zhang, Jing; Li, Fan

2014-01-01

295

Concentration of polycyclic aromatic hydrocarbons (PAHs) in moss (Hypnum cupressiforme) from Hungary.  

PubMed

Mosses of the species Hypnum cupressiforme were collected from different parts of Hungary to investigate the air quality of the region. The concentrations of polycyclic aromatic hydrocarbons (PAHs) in species were determined. Low molecular weight PAHs (up to three ring compounds) contribute more than 99% to the concentrations of PAHs in Moss samples. The pattern of PAHs suggests local sources rather than long-range transport of contamination in the air. Possible local sources are industrial, urban, and traffic activities. The results indicate incomplete combustion of fuel is largely responsible for the air quality of the area. PMID:14533926

Kozák, Imre Olivér; Kozák, Melinda; Fekete, Jeno; Sharma, Virender K

2003-01-01

296

Interrelationship of Pyrogenic Polycyclic Aromatic Hydrocarbon (PAH) Contamination in Different Environmental Media.  

PubMed

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. PMID:22303141

Kim, Seung-Kyu; Lee, Dong Soo; Shim, Won Joon; Yim, Un Hyuk; Shin, Yong-Seung

2009-01-01

297

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

298

The PAH mutation analysis consortium database: update 1996.  

PubMed Central

A website (http://www.mcgill.ca/pahdb ) is maintained by the curators for a Consortium (88 investigators, 28 countries) and all other users; it serves a relational database for human locus-specific genetic variation in a defined DNA sequence (GenBank U49897); (100 kb on human chromosome 12q24.1, gene symbol PAH). The intragenic nucleotide variation is both rare (Q< 0.01), extensive (>320 different mutations) and phenotype modifying, causing hyperphenylalaninemia by impairing phenylalanine hydroxylase function (see OMIM 261600), as well as polymorphic and neutral, the latter providing informative locus-specific haplotypes (>1200 different mutation/haplotype associations). The PAH database contains both offline core components (mutations, population associations and data source information) and several accessory online components: (i) relative frequencies of mutations by populations/regions (expanding file); (ii) data on genotype- phenotype correlations both in vitro and in vivo (new file); (iii) polymorphic haplotype structures (new file); (iv) intron sequence data (new file for design of primers); (v) description of mouse homologues (new file for mutations and phenotypes); (vi) the predicted PAH gene mutability profile (improved graphic); (vii) a clinical field for patient use (new interface with database). The website home page has been revised and a counter is recording >15 visits per day. Linkages to other mutation databases and an alliance of mutation database curators (new) are expanding. The primary 'electronic publication' reports now vastly exceed print reports. PAHdb serves as a prototype for obtaining, storing and distributing records of human genetic variation. PMID:9016524

Nowacki, P; Byck, S; Prevost, L; Scriver, C R

1997-01-01

299

Constraints on accretion in Ultraluminous X-ray Sources from Spitzer IRS observations of NGC 4485/90: Infrared diagnostic diagrams  

E-print Network

Constraining the astrophysical nature of Ultra-Luminous X-ray (ULX) sources, which have X-ray luminosities exceeding 10^39 erg/s, has been elusive due to the optical faintness of any counterparts. With high spectral resolution observations in the ~10-30 microns wavelength range we have conducted an experiment to study six ULX sources in the NGC 4485/90 galaxy pair. We have found that five of the six ULXs, based on mid-infrared spectral diagnostics, show the characteristic higher ionization features that are found in AGN. The sixth source, ULX-1, is consistent with being a supernova remnant. The chief infrared spectral diagnostics used are the ratios of [S III]/[Si II] vs [Ne III}]/[Ne II]. In two instances fits to the continuum and poly aromatic hydrocarbons (PAH) features also indicate higher dust temperatures that are characteristic of accreting sources. Overall, however, we find the continuum is dominated by stellar processes, and the best diagnostic features are the emission lines. High spectral resolution studies in the mid-infrared thus appear to show great promise for determining the astrophysical nature of ULXs.

Gerardo A. Vazquez; Ann E. Hornschemeier; Edward Colbert; Tymothy P. Roberts; Martin J. Ward; Sangeeta Malhotra

2007-02-09

300

Effects of in-reservoir weathering on PAH source characterization parameters  

SciTech Connect

Use of petroleum biomarkers to evaluate sources and degradation processes have been a pail of mainstream petroleum geochemistry field for over 15 years. Only recently have similar approaches been widely used as a means to determine the source of petroleum products released into the environment and to help allocate any associated environmental liability among responsible parties. Of special interest in the environmental field has been the use of polycyclic aromatic hydrocarbons (PAM, parents plus alkylated homologues) to {open_quotes}fingerprint{close_quotes} petroleum mixtures containing mid-range distillate components (e.g., whole oils, diesels, etc.). This has been particularly useful in the case of diesel fuels which do not contain substantial amounts of classical sterane and hopane biomarkers and which upon weathering readily loss diagnostic resolvable compounds (e.g., alkanes and isoprenoids). The objective of this study was to exploit the knowledge that a sample had a common source and evaluate the effect of weathering on the alkylated PAH concentration.

Haddad, R.I. [ENTRIX, Inc., Walnut Creek, CA (United States); Stout, S.A. [UNOCAL Corp., Brea, CA (United States)

1996-12-31

301

Effect of Substrate Character on Heterogeneous Ozone Reaction Rate with Individual PAHs and Their Reaction Mixtures  

NASA Astrophysics Data System (ADS)

Vehicle exhaust contains many unregulated chemical compounds that are harmful to human health and the natural environment, including polycyclic aromatic hydrocarbons (PAH), a class of organic compounds derived from fuel combustion that can be carcinogenic and mutagenic. PAHs have been quantified in vehicle-derived ultrafine particles (Dp<100nm), which are more toxic than larger particles and are linked to adverse health problems, including respiratory and cardiac disease. Once emitted into the atmosphere, particle-bound PAHs can undergo “aging” reactions with oxidants, such as ozone, to form more polar species. These polar reaction products include species such as quinones that can be more toxic than the parent PAH compounds. Here, 0.4ppm ozone was reacted over a 24-hour period with the 16 EPA priority PAHs plus coronene adsorbed to (i) a quartz fiber filter and (ii) NIST diesel PM. The difference in the PAH/O3 heterogeneous reaction rate resulting from the two substrates will be discussed. The experiments were completed by spiking a known PAH mixture to the solid, reacting the samples with gas-phase ozone, and determining both PAH loss over time and products formed, using thermal-desorption gas chromatography / mass spectrometry (TD-GC/MS). The individual PAHs anthracene, phenanthrene, and fluorene, adsorbed to a QFF were also separately reacted with 0.4 ppm ozone. A volatilization control and the collection of volatilized PAHs using a Tenax-packed thermal desorption vial completed the mass balance and aided determination parent-product relationships. Heterogeneous reaction products analyzed directly without derivatization indicate the formation of 9,10-anthracenedione, 9H-fluoren-9-one, and (1,1’-biphenyl)-2,2’-dicarboxaldehyde from the reaction of ozone with the PAH mix on a QFF, but only 9,10-anthracenedione was detected for the diesel PM reaction. The implications of these results for aging of diesel particulate in urban environments will be discussed.

Holmen, B. A.; Stevens, T.

2009-12-01

302

Multivariate analysis of mixed contaminants (PAHs and heavy metals) at manufactured gas plant site soils.  

PubMed

Principal component analysis (PCA) was used to provide an overview of the distribution pattern of polycyclic aromatic hydrocarbons (PAHs) and heavy metals in former manufactured gas plant (MGP) site soils. PCA is the powerful multivariate method to identify the patterns in data and expressing their similarities and differences. Ten PAHs (naphthalene, acenapthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo[a]pyrene) and four toxic heavy metals - lead (Pb), cadmium (Cd), chromium (Cr) and zinc (Zn) - were detected in the site soils. PAH contamination was contributed equally by both low and high molecular weight PAHs. PCA was performed using the varimax rotation method in SPSS, 17.0. Two principal components accounting for 91.7% of the total variance was retained using scree test. Principle component 1 (PC1) substantially explained the dominance of PAH contamination in the MGP site soils. All PAHs, except anthracene, were positively correlated in PC1. There was a common thread in high molecular weight PAHs loadings, where the loadings were inversely proportional to the hydrophobicity and molecular weight of individual PAHs. Anthracene, which was less correlated with other individual PAHs, deviated well from the origin which can be ascribed to its lower toxicity and different origin than its isomer phenanthrene. Among the four major heavy metals studied in MGP sites, Pb, Cd and Cr were negatively correlated in PC1 but showed strong positive correlation in principle component 2 (PC2). Although metals may not have originated directly from gaswork processes, the correlation between PAHs and metals suggests that the materials used in these sites may have contributed to high concentrations of Pb, Cd, Cr and Zn. Thus, multivariate analysis helped to identify the sources of PAHs, heavy metals and their association in MGP site, and thereby better characterise the site risk, which would not be possible if one uses chemical analysis alone. PMID:21789533

Thavamani, Palanisami; Megharaj, Mallavarapu; Naidu, Ravi

2012-06-01

303

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. PMID:24722336

He, Xiaosheng; Feng, Yingying; Yang, Liangle; Zhu, Xiaoyan; Deng, Qifei; Wu, Tangchun; Zhang, Xiaomin

2014-01-01

304

PAHs in the Chinese environment: levels, inventory mass, source and toxic potency assessment.  

PubMed

This paper presents a systematic but preliminary study on the levels, inventory mass, emission sources and risk of exposure to PAHs in China by examining 14 polycyclic aromatic hydrocarbons (from the 16 priority PAHs listed by the U.S. EPA, excluding naphthalene and acenaphthylene) in four main environmental media (air, water, soil and sediment). The concentration of individual PAHs in the air, soil, freshwater, seawater, freshwater sediment and marine sediment of China was compared with the global concentration range (GCR) of PAHs from a large number of studies. The PAH levels were found at the high end of the GCR in the air, at the upper middle of the GCR in the water body, and at the middle of the GCR in the soil and sediment. These indicate that PAHs still are emitted heavily in China. About 530?000 tons of ?14PAH was estimated to be distributed into these four media in China. Soil possesses the highest proportion of the PAHs (60%), and the air has the lowest proportion (<0.5%). Therefore, the soil and sediment play an important role in the storage of PAHs. More than 10 thousand tons of PAHs are emitted from all kinds of sources. Firewood, straw, domestic and coking were considered as the main emissions of PAHs in the energy supply. A benzo[a]pyrene (BaP) based hazard quotient (HQ) was introduced to assess the potential toxic risk of exposure. The terrestrial water environment was found to have a high BaP exposure. The HQ value was more than 1 for 58% of freshwater and 39% of freshwater sediment samples. Urban and developed sites were considered to have high BaP exposure risk. PMID:23665869

Wang, Ji-Zhong; Zhu, Cheng-Zhu; Chen, Tian-Hu

2013-06-01

305

Batch leaching tests: Colloid release and PAH leachability  

SciTech Connect

The Toxicity Characteristic Leaching Procedure (TCLP) was developed by the U.S. Environmental Protection Agency to assess leaching potential of contaminants from waste, and to provide a test to classify, hazardous waste. It is a batch leaching test where a waste (such as contaminated soil) and an extraction fluid are agitated for a predetermined time. Since TCLP employs an aggressive mixing technique, it is possible that hydrophobic contaminant-laden colloidal fractions may appear as 'dissolved' constituents. In this study, TCLP was employed to determine the leachability of PAH contamination from a coal tar contaminated site. Generated colloids and the apparent aqueous concentrations of naphthalene and phenanthrene were measured at various mixing times in the extraction fluid. A mathematical model was developed that predicted the apparent aqueous contaminant concentration in the filtrate. This model accounted for the presence of colloids in the filtrate, and quantified contaminant desorption from colloids. The fraction of colloid-bound contaminant was predicted to be negligible for naphthalene. However, phenanthrene was predicted to have a significant fraction of the total contaminant in the colloidal phase, while naphthalene was primarily dissolved. The desorption model and PAH desorption data are presented here to determine the extent of colloid-facilitated desorption during leaching tests.

Bergendahl, J. [Worcester Polytechnique Institute, Worcester, MA (United States). Dept. of Civil & Environmental Engineering

2005-07-01

306

Degradation of PAHs in soil by indigenous and inoculated bacteria  

SciTech Connect

In soil heavily polluted by coal tar, the inherent mineralization of radio-labeled phenanthrene to {sup 14}CO{sub 2} was relatively slow, and a stimulation of degradation was observed by inoculation with a mixed population of PAH-degrading bacteria. A much faster inherent mineralization of phenanthrene was observed in soil slightly polluted by coal tar, and inoculation of this soil had no effect. Several phenanthrene-degrading bacteria were isolated from different soils. Two strains were further characterized as an Arthrobacter sp. and a Pseudomonas sp. In an organic medium without phenanthrene, growth rates of 0.52 h{sup {minus}1} and 0.71 h{sup {minus}1} were measured for the Arthrobacter sp. and the Pseudomonas sp., respectively. Most isolates grown in the phenanthrene-free medium, including the Arthrobacter sp., rapidly adapted to phenanthrene degradation following transfer to a phenanthrene-containing medium. In contrast, the phenanthrene-degrading capability of other strains, including the Pseudomonas sp., was lost during growth in the phenanthrene-free medium. Growth in an organic medium without phenanthrene of strains that retain the ability to degrade phenanthrene could prove to be a useful technique for production of PAH-degrading bacteria on a larger scale for soil inoculation.

Aamand, J. [Geological Survey of Denmark, Copenhagen (Denmark); Bruntse, G.; Jepsen, M.; Joergensen, C.; Jensen, B.K. [VKI Water Quality Inst., Hoersholm (Denmark)

1995-12-31

307

Use of microbial encapsulation/immobilization for biodegradation of PAHs  

SciTech Connect

Bioaugmentation as a strategy in bioremediation has great potential but has had little success to support its use. Problems have arisen because of a general inability to support the growth and/or activity of the introduced organism in the environment because of competition factors, poor survival of the inoculum, and grazing by protozoa. A specialized technique that has been used to overcome these problems is cell immobilization or encapsulation, in which the inoculant can be placed in environmental media in a way that reduces competition from the indigenous microflora and allows expression of the specific introduced metabolic function. Packaging of specific bacterial or fungal cells in a porous polymeric material potentially improves storage of inocula, and enhances the capability of directly introducing viable and active cells into environmental material at some future time without the need to regrow the cells. The authors have been experimenting with encapsulation;immobilization procedures for use in the bioremediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soil. In this paper, the authors demonstrate the potential usefulness of polyurethane foam and vermiculite for this purpose and show that optimal PAH degradation can be maintained with immobilized cells.

Lin, J.E. [Sybron Chemicals, Inc., Salem, VA (United States). Biochemical and Environmental Services; Lantz, S.; Mueller, J.G. [SBP Technologies, Inc., Gulf Breeze, FL (United States); Schultz, W.W. [Naval Research Lab., Edgewater, MD (United States); Pritchard, P.H. [Environmental Protection Agency, Gulf Breeze, FL (United States)

1995-12-31

308

Comparative study on the growth mechanisms of PAHs  

SciTech Connect

The efficiencies of recently proposed, phenyl addition/cyclization (PAC), methyl addition/cyclization (MAC) and a popular hydrogen abstraction/acetylene addition (HACA) mechanisms have been examined experimentally by detecting the gas phase reaction products of pyrolysis of toluene with/without addition of benzene + acetylene by using vacuum ultraviolet (VUV) single photon ionization (SPI) time of flight mass spectrometry (TOFMS). Besides the observation of verities of large polycyclic aromatic hydrocarbons (PAHs), intense mass peaks of indene, phenylacetylene and propyne confirmed a remarkable quenching of the major active species, benzyl, phenyl and methyl radicals by acetylene. In spite of quenching, only benzyl contributed products were diminished while phenyl and methyl contributed products were enhanced. Uniquely observed symmetrical PAHs; corrannulene/coronene; formed by the active involvement of PAC, HACA and/or MAC mechanisms, reflects the interdependencies of these mechanisms. Individually, PAC was found highly efficient for endless growth, HACA for filling triple fusing site and MAC for expanding cyclotetra/pentafused into benzenoid structure, respectively. (author)

Shukla, Bikau; Koshi, Mitsuo [Department of Chemical System Engineering, University of Tokyo, Bunkyo-ku, Hongo, Tokyo 113-8656 (Japan)

2011-02-15

309

MAST magnetic diagnostics  

NASA Astrophysics Data System (ADS)

The mega-ampere spherical tokamak (MAST) experiment is a new, large, low aspect ratio device (R=0.7-0.8 m, a=0.5-0.65 m, maximum BT˜0.63 T at R=0.7 m) operating its first experimental physics campaign. Designed to study a wide variety of plasma shapes with up to 2 MA of plasma current with an aspect ratio down to 1.3, the poloidal field (PF) coils used for plasma formation, equilibrium and shaping are inside the main vacuum vessel. For plasma control and to investigate a wide range of plasma phenomena, an extensive set of magnetic diagnostics have been installed inside the vacuum vessel. More than 600 vacuum compatible, bakeable diagnostic coils are configured in a number of discrete arrays close to the plasma edge with about half the coils installed behind the graphite armour tiles covering the center column. The coil arrays measure the toroidal and poloidal variation in the equilibrium field and its high frequency fluctuating components. Internal coils also measure currents in the PF coils, plasma current, stored energy and induced currents in the mechanical support structures of the coils and graphite armour tiles. The latter measurements are particularly important when halo currents are induced following a plasma termination, for example, when the plasma becomes vertically unstable. The article describes the MAST magnetic diagnostic coil set and their calibration. The way in which coil signals are used to control the plasma equilibrium is described and data from the first MAST experimental campaign presented. These coil data are used as input to the code EFIT [L. Lao et al., Nucl. Fusion 25, 1611 (1985)], for measurement of halo currents in the vacuum vessel structure and for measurements of the structure of magnetic field fluctuations near the plasma edge.

Edlington, T.; Martin, R.; Pinfold, T.

2001-01-01

310

Learning About Ratios  

NSDL National Science Digital Library

Ratios appear in everyday life, but what exactly is a ratio. This lesson will help you understand what is a ratio and what to do with a ratio. What is a ratio? Dr. Math gives a pretty good explanation on these sites What is a ratio? Ratios as Fractions Figuring Ratios Writing Ratios Ratios Use this site to explore ratios using pictures All About Ratios Now that you have a little understanding here are some in-class activities that your teacher can help you with ...

Hadley, Mrs.

2005-06-17

311

DNA adduct formation in mammalian cell cultures by polycyclic aromatic hydrocarbons (PAH) and nitro-PAH in coke oven emission extract  

Microsoft Academic Search

Mammalian cells in culture were used to study the genotoxic potential of coke oven emissions constituting a complex mixture of chemicals. For this purpose, particle extracts and some polycyclic aromatic and nitroaromatic hydrocarbons (PAH and nitro-PAH) occurring in these mixtures were assayed for DNA adduct formation using the 32P-postlabeling technique. In primary cultures of rat hepatocytes, benzo[a]pyrene (B[a]P), benz[a]anthracene (B[a]A)

J. Topinka; L. R. Schwarz; F. Kiefer; F. J. Wiebel; O. Gajdoš; P. Vidová; L. Dobiáš; M. Fried; R. J. Šrám; T. Wolff

1998-01-01

312

Identifying sources of polycyclic aromatic hydrocarbons (PAHs) in soils: distinguishing point and non-point sources using an extended PAH spectrum and n -alkanes  

Microsoft Academic Search

Background, aim, and scope  Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants. They are formed during pyrogenic and diagenetic\\u000a processes and are components of petrogenic materials such as oils and coals. To identify PAH sources, several studies have\\u000a employed forensic methods, which may be costly to execute. Although a large number of possible forensic methods are available\\u000a (e.g., total ion chromatograms,

Carmen Pies; Thomas A. Ternes; Thilo Hofmann

2008-01-01

313

Bioaccumulation and critical body residue of PAHs in the amphipod, Diporeia spp: additional evidence to support toxicity additivity for PAH mixtures.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) are considered to act additively when exposed as congener mixtures. Additive internal concentrations at the site of toxic action is the basis for recent efforts to establish a sum PAH guideline for sediment-associated PAH toxicity. This study determined the toxicity of several PAH congeners on a body residue basis in Diporeia spp. These values were compared to the previously established LR(50) value for a PAH mixture based on the molar sum of PAH congeners and demonstrated similar LR(50) values for individual PAH. These results support the contention that the PAH act at the same molar concentration whether present as individual compounds or in mixture. Aqueous exposures were conducted for 28 d, and the water was exchanged daily to maintain the exposure concentration. The concentration in the exposures declined by an average of 22% between water exchanges across all compounds, and ranged from 11% to 32%. The toxicokinetics were determined using both time-weighted-average (TWA) and time-variable water concentrations and were not statistically different between the two source functions. Toxicity was determined for both mortality and immobility (failure to swim on prodding) and on both a TWA water concentration and a body residue basis. The LC(50) values ranged from 1757 microg l(-1) for naphthalene after 10 d exposure to 79.1 microg l(-1) for pyrene after 28 d exposure, and the EC(50) ranged from 1587 microg l(-1) for naphthalene after 10 d exposure to 38.2 microg l(-1) for pyrene after 28 d exposure. The LR(50) values for all congeners at all lengths of exposure were essentially constant and averaged 7.5+/-2.6 micromol g(-1), while the ER(50) for immobility averaged 2.6+/-0.6 micromol g(-1). The bioconcentration factor declined with increasing exposure concentration and was driven primarily by a lower uptake rate with increasing dose, while the elimination remained essentially constant for each compound. PMID:12615100

Landrum, Peter F; Lotufo, Guilherme R; Gossiaux, Duane C; Gedeon, Michelle L; Lee, Jong-Hyeon

2003-05-01

314

Coal-Tar-Based Parking Lot Sealcoat: An Unrecognized Source of PAH to Settled House Dust  

PubMed Central

Despite much speculation, the principal factors controlling concentrations of polycyclic aromatic hydrocarbons (PAH) in settled house dust (SHD) have not yet been identified. In response to recent reports that dust from pavement with coal-tar-based sealcoat contains extremely high concentrations of PAH, we measured PAH in SHD from 23 apartments and in dust from their associated parking lots, one-half of which had coal-tar-based sealcoat (CT). The median concentration of total PAH (T-PAH) in dust from CT parking lots (4760 ?g/g, n = 11) was 530 times higher than that from parking lots with other pavement surface types (asphalt-based sealcoat, unsealed asphalt, concrete [median 9.0 ?g/g, n = 12]). T-PAH in SHD from apartments with CT parking lots (median 129 ?g/g) was 25 times higher than that in SHD from apartments with parking lots with other pavement surface types (median 5.1 ?g/g). Presence or absence of CT on a parking lot explained 48% of the variance in log-transformed T-PAH in SHD. Urban land-use intensity near the residence also had a significant but weaker relation to T-PAH. No other variables tested, including carpeting, frequency of vacuuming, and indoor burning, were significant. PMID:20063893

2010-01-01

315

Screening of compost for PAHs and pesticides using static subcritical water extraction  

Microsoft Academic Search

Static subcritical water extraction (SubWE) along with solid phase extraction (SPE) was used for the analysis of PAHs and pesticides in municipal solid waste compost. Yields obtained for PAHs in certified reference sediment (CRM 104) were acceptable. The extraction method was simple, rapid, used small sample sizes, and no sample drying was required. Analysis of samples was performed by GC\\/MS

Audrey E. McGowin; Kafui K. Adom; Anne K. Obubuafo

2001-01-01

316

Screening of compost for PAHs and pesticides using static subcritical water extraction.  

PubMed

Static subcritical water extraction (SubWE) along with solid phase extraction (SPE) was used for the analysis of PAHs and pesticides in municipal solid waste compost. Yields obtained for PAHs in certified reference sediment (CRM 104) were acceptable. The extraction method was simple, rapid, used small sample sizes, and no sample drying was required. Analysis of samples was performed by GC/MS and HPLC. Recovery of spiked pesticides was greatest at 110 degrees C for 20 min extraction time. The optimum extraction for PAH analysis was achieved at 150 degrees C for 20 min. Addition of C-18 resin as an "alternate sorbent" upon cooling increased recovery of PAHs but not of pesticides, however, it increased the stability of atrazine and propazine at higher temperatures. Analysis of three municipal compost samples from the Dayton, OH (USA) area showed no pesticides above the detection limit, however, PAH totals for 11 PAHs were 15.97, 14.42, and 20.79 microg g(-1). The totals of six of the seven carcinogenic PAHs, for which remediation goals in the United States is 4.6 microg g(-1), were determined to be 9.89, 6.77, and 13.06 microg g(-1) dry weight. The highest PAH totals were obtained from compost containing sewage sludge. PMID:11695606

McGowin, A E; Adom, K K; Obubuafo, A K

2001-11-01

317

Inhibitory effects of polycyclic aromatic hydrocarbons (PAHs) on photosynthetic performance are not related to their aromaticity.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) are very toxic and highly persistent environmental pollutants which accumulate in soil and affect growth of the plants adversely. This study aims to investigate inhibitory effects of 3 major PAH particularly on photosynthetic processes in Arabidopsis thaliana grown in soil treated with PAH. The 3 PAH chosen differ from each other in aromaticity (number of rings) comprising their structure (2 rings: naphthalene, 3 rings: anthracene and 4 rings: pyrene). Several growth parameters and Chlorophyll a fluorescence was monitored in PAH treated plants. BN-PAGe analysis was done in order to get information about change in the protein conformation. PAH treatment led to increased value of Fo which collaborated with increase in the amount of free LHC as seen through BN-Page analysis. Thus PAH were found to inhibit PS II photochemistry and caused distinct change in pigment composition. However the results led us to infer that 3-ring anthracence is more inhibitory as compared to 2-ring naphthalene and 4-ring pyrene. This indicates that aromaticity of PAH is unrelated to their response on photosynthetic processes. PMID:24793324

Jajoo, Anjana; Mekala, Nageswara Rao; Tomar, Rupal Singh; Grieco, Michele; Tikkanen, Mikko; Aro, Eva-Mari

2014-08-01

318

Biliary PAH metabolites and the hepatosomatic index of brown bullheads from Lake Erie tributaries  

USGS Publications Warehouse

In studies designed to investigate the environmental exposure of fish in Lake Erie tributaries, a benthic fish, the brown bullhead (Ameiurus nebulosus), was collected from the industrially contaminated Detroit River, Ottawa River, Black River, Cuyahoga River-harbor and -upstream, Ashtabula River, Buffalo River, and Niagara River, and the non-industrialized Old Woman Creek during 1997-2000. Biliary benzo[a]pyrene (B[a]P)- and naphthalene (NAPH)-type metabolites and the hepatosomatic index (HSI) were measured in fish and compared between different sites. Fish from all of the contaminated sites except Niagara River had significantly higher concentrations of both types of polycyclic aromatic hydrocarbon (PAH) metabolites than fish from the Old Woman Creek. Concentrations of PAH metabolites in bile of fish were positively associated with concentrations of PAHs in sediments, supporting the use of bile metabolites as a measure of PAH exposure. Relatively low concentrations of PAHs detected in fish bile and sediments of the Niagara River, which had undergone extensive remediation, suggested a lowered PAH exposure for fish at this site. No apparent trend was observed in HSI between the industrialized and non-industrialized sites. This study demonstrates that biliary PAH metabolites are an effective indicator of exposure of fish to PAHs. However, because factors other than contamination could also affect the liver size of wild fish, HSI alone may be not a reliable biomarker for assessing contaminant stress. ?? 2005 Elsevier Ltd. All rights reserved.

Yang, X.; Baumann, P. C.

2006-01-01

319

PAHs in aquatic sediment in Hangzhou, China: analytical methods, pollution pattern, risk assessment and sources.  

PubMed

Eleven surface sediment samples, from Hangzhou section of Qiantang River and Jinghang Canal, west Lake the inland river were collected to investigate 17 polycyclic aromatic hydrocarbons (PAHs) pollution in aquatic sediments of Hangzhou. Accelerated solvent extraction(ASE) was used to extract PAHs from sediments with satisfactory recoveries. It was found that the total PAHs in the sediments ranged from 308.4 to 3037 ng/g dw, and PAHs pollution in sediments from Jinghang Canal were the heaviest. Lowest effect level (LEL) and severe effect level (SEL) sediment quality guidelines were introduced to perform risk assessment for PAHs pollution in aquatic sediments. Only one sample in Jinghang Canal had adverse impact on benthic organism. 2-3 ring PAHs had a noticeable contribution to total PAHs, especially NA, PHEN. A quantity method was used to determine the major source, the results showed petroleum origin was the chief source to PAHs pollution in all sediments with the exception of sediments from Jinghang Canal where combustion sources had a larger contribution. PMID:16312996

Zhu, Li-zhong; Cai, Xue-fen; Wang, Jing

2005-01-01

320

Polynuclear aromatic hydrocarbons (PAHs) mediate cadmium toxicity to an emergent wetland species  

Microsoft Academic Search

Growth and pollutant removal by emergent wetland plants may be influenced by interactions among mixed pollutants in constructed wetlands. A glasshouse experiment was conducted to investigate interactive effects of cadmium (Cd)×polynuclear aromatic hydrocarbons (PAHs)×plant treatments on growth of Juncus subsecundus, Cd and PAH removal from soil and the total number of microorganisms in soil. Growth and biomass of J. subsecundus

Zhenhua Zhang; Zed Rengel; Kathy Meney; Ljiljana Pantelic; Radmila Tomanovic

2011-01-01

321

23. Method development for the determination of polycyclic aromatic hydrocarbons (PAHs) in environmental matrices  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs) and some of their derivatives represent a class of important environmental pollutants possessing a high mutagenic and carcinogenic potential as proven by in vitro experiments with various animal species using different modes of application and in vitro experiments using tissue homogenates, cells in culture and subcellular fractions as well [1,2].PAHs are ubiquitous in the environment, although

J. Jacob

1995-01-01

322

Measurement of gaseous PAHs with an innovative passive sampler in community exposure studies  

EPA Science Inventory

A sensitive, simple, and cost-effective passive sampling methodology was developed to quantify gaseous polycyclic aromatic hydrocarbons (PAHs) in personal, indoor and outdoor air. A Fan-Lioy passive PAH sampler (FL-PPS) is constructed from four 80 sections of 1 cm long SPB-5 GC c...

323

Removal of polycyclic aromatic hydrocarbons (PAHs) from sewage sludge by anaerobic degradation  

Microsoft Academic Search

Due to the hydrophobic nature of the polyaromatic hydrocarbons (PAHs) they are mostly bound to the sludge and escape aerobic treatment in a wastewater treatment plant. They therefore proceed directly to the anaerobic post treatment, terminate in the sludge, and can be released to the environment if land spreading is used. PAH degradation in anaerobic methanogenic systems has only recently

N. Christensen; D. J. Batstone; Z. He; I. Angelidaki; J. E. Schmidt

2004-01-01

324

BILIARY PAH METABOLITES AS A BIOLOGICAL INDICATOR OF FISH EXPOSURE IN TRIBUTARIES OF LAKE ERIE  

EPA Science Inventory

Biliary polynuclear aromatic hydrocarbons (PAH) metabolites have been studied as a biological indicator of fish exposure to PAHs since the mid 1980's. Brown bullheads were collected from the following Lake Erie tributaries: Buffalo River (BUF), Niagara River at Love Canal (NIA)...

325

Occurrence and Fate of PAHs from Road Runoff in the South Drainage Basin of Annecy Lake  

Microsoft Academic Search

The nature and concentration of Polycyclic Aromatic Hydrocarbons (PAHs) from main road runoff were evaluated in several potential deposition areas close to Annecy Lake. Investigations were conducted on sediments from road lining ditches, surface sediments, surface water of the lake, Eau Morte river, stagnant water from a natural reserve. Sixteen common PAHs were studied and the concentration determined monthly from

E. Naffrechoux; E. Combet; B. Fanget; L. Paturel; F. Berthier

2000-01-01

326

PAHs in Road Dust: Ubiquity, Fate, and Summary of Available Data  

Microsoft Academic Search

Polyaromatic hydrocarbons (PAH) are ubiquitous in environment and are also present in road dust in urban and rural locations worldwide due to the mere presence of even a weak primary source and the dynamic interconnection among all environmental segments. Although monitoring and assessment of PAHs in road dust have been undertaken in several countries, compilation of information on the dynamics

Deepanjan Majumdar; Bhargavi Rajaram; Shweta Meshram; C. V. Chalapati Rao

2012-01-01

327

POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) IN EGGS FROM GANNETS, GOLDEN EAGLES AND MERLINS  

Microsoft Academic Search

7,8 . The presence of detectable PAHs residues and metabolites in the body tissues and eggs of some biota 9 indicates that exposure does occur. PAHs in birds are often associated with lipids, bioaccumulation tending to occur not only in the livers but also in eggs where residues can be two or three orders of magnitude higher than in livers

M. Glória Pereira; Lee A. Walker; Julian Wright; Jennifer Best; Richard F. Shore

328

Modeling PAH mass transfer in a slurry of contaminated soil or sediment amended with organic sorbents  

Microsoft Academic Search

A three-compartment kinetic partitioning model was employed to assess contaminant mass transfer and intraparticle diffusion in systems comprising dense slurries of polluted soil or aquifer sediment with or without sorbent amendments to sequester polycyclic aromatic hydrocarbons (PAHs). The model was applied to simulate temporal changes in aqueous and particle-bound PAH concentrations comparing different pollution sources (heavy oil or tar sludge)

Sungwoo Ahn; David Werner; Richard G. Luthy

2008-01-01

329

Rinodina sophodes (Ach.) Massal.: a bioaccumulator of polycyclic aromatic hydrocarbons (PAHs) in Kanpur City, India.  

PubMed

The aim of this study is to determine the possibility of using Rinodina sophodes (Ach.) Massal., a crustose lichen as polycyclic aromatic hydrocarbons (PAHs) bioaccumulator for evaluation of atmospheric pollution in tropical areas of India, where few species of lichens are able to grow. PAHs were identified, quantified and compared to evaluate the potential utility of R. sophodes. The limit of detection for different PAHs was found to be 0.008-0.050 ?g g(?-?1). The total PAHs in different sites were ranged between 0.189 ± 0.029 and 0.494 ± 0.105 ?g g(?-?1). The major sources of PAHs were combustion of organic materials, traffic and vehicular exhaust (diesel and gasoline engine). Significantly higher concentration of acenaphthylene and phenanthrene indicates road traffic as major source of PAH pollution in the city. Two-way ANOVA also confirms that all PAHs content showed significant differences between all sampling sites (P 1%). This study establishes the utility of R. sophodes in monitoring the PAHs accumulation potentiality for development of effective tool and explores the most potential traits resistant to the hazardous environmental conditions in the tropical regions of north India, where no such other effective way of biomonitoring is known so far. PMID:21465135

Satya; Upreti, Dalip K; Patel, D K

2012-01-01

330

NHEXAS PHASE I MARYLAND STUDY--QA ANALYTICAL RESULTS FOR PAHS IN BLANKS  

EPA Science Inventory

The PAHs in Blanks data set contains the analytical results of measurements of up to 11 polynuclear aromatic hydrocarbons (PAHs) in 20 blank samples from 14 households. Measurements were made in blank samples of indoor air, dust, and soil. Blank samples were used to assess the ...

331

Bioaccumulation and critical body residue of PAHs in the amphipod, Diporeia spp.: additional evidence to  

E-print Network

Bioaccumulation and critical body residue of PAHs in the amphipod, Diporeia spp.: additional. This study determined the toxicity of several PAH congeners on a body residue basis in Diporeia spp. Published by Elsevier Science Ltd. Keywords: Polycyclic aromatic hydrocarbons; Diporeia spp.; Lethal body

332

Anaerobic PAH degradation in soil by a mixed bacterial consortium under denitrifying conditions  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs) are one of the main classes of contaminants in the terrestrial environment. Concentrations of biphenyl, fluorene, phenanthrene and pyrene were added to soil samples in order to investigate the anaerobic degradation potential of PAHs under denitrifying conditions. A mixed population of microorganisms obtained from a paddy soil was incubated for 20days in anaerobic conditions in the

Roberto Ambrosoli; Laura Petruzzelli; José Luis Minati; Franco Ajmone Marsan

2005-01-01

333

Identification of Sediment Organic Carbon Location and Association with Polycyclic Aromatic Hydrocarbons (PAHs) in Contaminated Sediment  

E-print Network

Hydrocarbons (PAHs) in Contaminated Sediment Upal Ghosh1 , Richard G. Luthy1 , J. Seb Gillette2 , and Richard N is known about the mechanisms of PAH and other hydrophobic organic compound sequestration and aging successful sediment bioremediation is the availability of contaminants to microorganisms for degradation

334

PAH dissipation in a contaminated river sediment under oxic and anoxic conditions  

Microsoft Academic Search

A batch experiment was conducted to compare PAH degradation in a polluted river sediment under aerobic and anaerobic conditions, and to investigate whether input of fresh organic material (cellulose) could enhance such degradation. All measurements were checked against abiotic control treatments to exclude artifacts of sample preparation and non-biological processes like aging. Three- and four-ring PAHs could be degraded by

C. Quantin; E. J. Joner; J. M. Portal; J. Berthelin

2005-01-01

335

Insights into the genetic diversity of initial dioxygenases from PAH-degrading bacteria  

Microsoft Academic Search

Alpha subunit genes of initial polyaromatic hydrocarbon (PAH) dioxygenases were used as targets for the PCR detection of PAH-degrading strains of the genera Pseudomonas, Comamonas and Rhodococcus which were obtained from activated sludge or soil samples. Sequence analysis of PCR products from several Pseudomonas strains showed that alpha subunits (nahAc allele) of this genus are highly conserved. PCR primers for

Ralf Moser; Ulf Stahl

2001-01-01

336

Microcosm studies of subsurface PAH-degrading bacteria from a former manufactured gas plant  

Microsoft Academic Search

A study was conducted to evaluate the potential for natural in situ biodegradation of polycyclic aromatic hydrocarbons (PAH's) in the subsurface at the site of a former manufactured gas plant. Fifty-seven samples of unconsolidated subsurface sediments were aseptically obtained from five boreholes across the site. Bacteria capable of aerobically degrading PAH's without an acclimation period were detected throughout shallow (2.7

Neal D. Durant; Liza P. Wilson; Edward J. Bouwer

1995-01-01

337

MEASURING AIRBORNE PAHS FROM THE NEW YORK WORLD TRADE CENTER DISASTER  

EPA Science Inventory

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in ambient air, are suspected human carcinogens, and have been linked to genotoxic and mutagenic effects. Although there are no specific monitoring programs for PAHs in ambient air in the United States, there is a national...

338

Variations in the 3 Micron Spectrum Across the Orion Bar: PAHS and Related Molecules  

NASA Technical Reports Server (NTRS)

Long-slit spectra across the Orion Bar reveal significant differences in the spatial behavior of the components of the 3 micrometer PAH spectrum. The strong PAH band at 3.29 micrometers generally decreases exponentially with distance from the ionization front into the molecular cloud (scale height approximately 12"), although excesses appear approximately 10" and approximately 20" behind the ionization front, close to layers of H2 and CO emission respectively. The 3.40 micrometer PAH feature separates into two components with very different spatial distributions. The main component (at 3.395 micrometers), along with the 3.51 micrometer band and the PAH plateau (3.3-3.6 micrometers), shows excess emission approximately 10" and approximately 20" behind the ionization front, stronger than the excesses in the 3.29 micrometer band. The extra component of the 3.40 micrometer band, which peaks at approximately 3.405 micrometers, has a spatial distribution very similar to the H2 emission. Aromatic C-H stretches in PAHs most likely produce the 3.29 micrometer feature. Aliphatic C-H stretches in either attached methyl sidegroups or super-hydrogenated PAHs (H-PAHs), or perhaps both, could produce the complicated spectral and spatial structure at 3.40 micrometers. The distribution of these fragile PAH-based species traces the physical and chemical conditions in the interface between the ionized region and molecular cloud.

Sloan, G. C.; Bregman, J. D.; Geballe, T. R.; Allamandola, L. J.; Woodward, C. E.; Wittborn, Fred C. (Technical Monitor)

1996-01-01

339

Statistical models for the accumulation of PAH, chlorinated hydrocarbons and trace metals in epiphytic Hypnum cupressiforme  

Microsoft Academic Search

Concentrations of PAH (1.12-benzoperylene, 3.4-benzopyrene, fluoranthene), chlorinated hydrocarbons (a-BHC, lindane, PCB) and trace metals (Zn, Pb, Cu) in bulk precipitation, as well as PAH and trace metal concentrations in atmospheric dust samples from 14 sites in Bavaria, F.R.G. are presented for two vegetation periods (1979 and 1980).

Wolfgang Thomas

1984-01-01

340

Analysis of smoke PAHs from selected Taiwanese cigarettes by using molecular imprinting polymers  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs) and their derivatives are common trace pollutants produced during incomplete combustion of organic substances, such as tobacco. After sampling cigarette smoke, PAH collators must undergo pretreatment processes such as extraction, cleanup and concentration before instrument analysis. This study combines molecular imprinted polymers (MIPs) and solid-phase extraction (SPE) to create a novel sample pretreatment technique. Experimental results

Wei L. Ho; Ta C. Lin; Yu Y. Liu; Jiun A. Chen

2010-01-01

341

FATE OF PAH COMPOUNDS IN TWO SOIL TYPES: INFLUENCE OF VOLATILIZATION, ABIOTIC LOSS, AND BIOLOGICAL ACTIVITY  

EPA Science Inventory

The fate of 14 polycyclic aromatic hydrocarbon (PAH) compounds was evaluated with regard to interphase transfer potential and mechanisms of treatment in soil under unsaturated conditions. Volatilization and abiotic and biotic fate of the PAHs were determined using two soils not p...

342

FATE OF PAH COMPOUNDS IN TWO SOIL TYPES: INFLUENCE OF VOLATILIZATION, ABIOTIC LOSS AND BIOLOGICAL ACTIVITY  

EPA Science Inventory

The fate of 14 polycyclic aromatic hydrocarbon (PAH) compounds was evaluated with regard to interphase transfer potential and mechanisms of treatment in soil under unsaturated conditions. olatilization and abiotic and biotic fate of the PAHs were determined using two soils not pr...

343

Nonadditive effects of PAHs on Early Vertebrate Development: mechanisms and implications for risk assessment  

PubMed Central

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants. Traditionally, much of the research has focused on the carcinogenic potential of specific PAHs, such as benzo(a)pyrene, but recent studies using sensitive fish models have shown that exposure to PAHs alters normal fish development. Some PAHs can induce a teratogenic phenotype similar to that caused by planar halogenated aromatic hydrocarbons, such as dioxin. Consequently, mechanism of action is often equated between the two classes of compounds. Unlike dioxins, however, the developmental toxicity of PAH mixtures is not necessarily additive. This is likely related to their multiple mechanisms of toxicity and their rapid biotransformation by CYP1 enzymes to metabolites with a wide array of structures and potential toxicities. This has important implications for risk assessment and management as the current approach for complex mixtures of PAHs usually assumes concentration addition. In this review we discuss our current knowledge of teratogenicity caused by single PAH compounds and by mixtures and the importance of these latest findings for adequately assessing risk of PAHs to humans and wildlife. Throughout, we place particular emphasis on research on the early life stages of fish, which has proven to be a sensitive and rapid developmental model to elucidate effects of hydrocarbon mixtures. PMID:18156145

Billiard, Sonya M.; Meyer, Joel N.; Wassenberg, Deena M.; Hodson, Peter V.; Di Giulio, Richard T.

2008-01-01

344

Effect of copper chloride on the emissions of PCDD/Fs and PAHs from PVC combustion.  

PubMed

The influences of temperature, air flow and the amount of copper chloride upon the types and amount of the toxic emissions such as polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and polycyclic aromatic hydrocarbons (PAHs) during combustion of polyvinyl chloride (PVC) were investigated. The mechanism concerning the effect of temperature and copper chloride on the PCDD/Fs and PAHs formation was discussed. The results shown that without copper chloride, trace amounts of PCDD/Fs and large amounts of PAHs were found in the emissions from the pure PVC combustion under various combustion conditions. The addition of copper chloride enhanced PCDD/Fs formation, but it seems that the formation of PAHs decreased with increasing amount of copper chloride, and greater total amount of PAHs were produced at the higher temperature under our experimental conditions. PMID:12222780

Wang, Dongli; Xu, Xiaobai; Zheng, Minghui; Chiu, Chung H

2002-09-01

345

Identification of petroleum hydrocarbons using a reduced number of PAHs selected by Procrustes rotation.  

PubMed

Identifying petroleum-related products released into the environment is a complex and difficult task. To achieve this, polycyclic aromatic hydrocarbons (PAHs) are of outstanding importance nowadays. Despite traditional quantitative fingerprinting uses straightforward univariate statistical analyses to differentiate among oils and to assess their sources, a multivariate strategy based on Procrustes rotation (PR) was applied in this paper. The aim of PR is to select a reduced subset of PAHs still capable of performing a satisfactory identification of petroleum-related hydrocarbons. PR selected two subsets of three (C(2)-naphthalene, C(2)-dibenzothiophene and C(2)-phenanthrene) and five (C(1)-decahidronaphthalene, naphthalene, C(2)-phenanthrene, C(3)-phenanthrene and C(2)-fluoranthene) PAHs for each of the two datasets studied here. The classification abilities of each subset of PAHs were tested using principal components analysis, hierarchical cluster analysis and Kohonen neural networks and it was demonstrated that they unraveled the same patterns as the overall set of PAHs. PMID:20005532

Fernández-Varela, R; Andrade, J M; Muniategui, S; Prada, D; Ramírez-Villalobos, F

2010-04-01

346

Degradation of Polycyclic Aromatic Hydrocarbons (PAHs) by Bacteria Isolated from Light Oil Polluted Soils  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbons (PAHs) have polluted soil and groundwater widely and for long term because of their low solubility at normal temperature. Several microorganisms, such as Pseudomonas sp., Sphigomonas sp., a white-rot fungus and so on, being able to decompose PAHs, have been isolated and researched. This study reported to investigate biodegradation of low molecule PAH by isolated bacteria from light oil polluted soil. 12 isolates were obtained from a light oil polluted soil using naphthalene, fluorene and anthracene as sole carbon source, of which 4 isolates grew with naphthalene, 4 isolates did with fluorene and 4 isolates did with anthracene. Among them 3 isolates showed the ability to degrade phenanthrene additionally. These phenanthrene degradation and growth rates were almost same as that of S. yanoikuyae (DSM6900), which is the typical bacteria of PAHs degrader. Therefore, the isolate seemed to have an expectation for PAHs degradation.

Ohnuma, T.; Suto, K.; Inoue, C.

2007-03-01

347

Ecotoxicity of a polycyclic aromatic hydrocarbon (PAH)-contaminated soil.  

PubMed

Soil samples from a former cokery site polluted with polycyclic aromatic hydrocarbons (PAHs) were assessed for their toxicity to terrestrial and aquatic organisms and for their mutagenicity. The total concentration of the 16 PAHs listed as priority pollutants by the US Environmental Protection Agency (US-EPA) was 2634+/-241 mg/kgdw in soil samples. The toxicity of water-extractable pollutants from the contaminated soil samples was evaluated using acute (Vibrio fischeri; Microtox test, Daphnia magna) and chronic (Pseudokirchneriella subcapitata, Ceriodaphnia dubia) bioassays and the EC values were expressed as percentage water extract in the test media (v/v). Algal growth (EC50-3d=2.4+/-0.2% of the water extracts) and reproduction of C. dubia (EC50-7d=4.3+/-0.6%) were the most severely affected, compared to bacterial luminescence (EC50-30 min=12+/-3%) and daphnid viability (EC50-48 h=30+/-3%). The Ames and Mutatox tests indicated mutagenicity of water extracts, while no response was found with the umu test. The toxicity of the soil samples was assessed on the survival and reproduction of earthworms (Eisenia fetida) and collembolae (Folsomia candida), and on the germination and growth of higher plants (Lactuca sativa L.: lettuce and Brassica chinensis J.: Chinese cabbage). The EC50 values were expressed as percentage contaminated soil in ISO soil test medium (weight per weight-w/w) and indicated severe effects on reproduction of the collembola F. candida (EC50-28 d=5.7%) and the earthworm E. fetida (EC50-28 d=18% and EC50-56 d=8%, based on cocoon and juvenile production, respectively). Survival of collembolae was already affected at a low concentration of the contaminated soil (EC50-28 d=11%). The viability of juvenile earthworms was inhibited at much lower concentrations of the cokery soil (EC50-14 d=28%) than the viability of adults (EC50-14 d=74%). Only plant growth was inhibited (EC50-17d=26%) while germination was not. Chemical analyses of water extracts allowed us to identify inorganic water-extractable pollutants as responsible for toxicity on aquatic species, especially copper for effects on D. magna and C. dubia. The soil toxicity on collembolae and earthworms could be explained by 4 PAH congeners-fluorene, phenanthrene, pyrene, and fluoranthene. Yet, toxicity of the cokery soil as a whole was much lower than toxicity that could be deduced from the concentration of each congener in spiked soils, indicating that pollutants in the soil became less bioavailable with ageing. PMID:17382389

Eom, I C; Rast, C; Veber, A M; Vasseur, P

2007-06-01

348

A statistical approach to develop a detailed soot growth model using PAH characteristics  

SciTech Connect

A detailed PAH growth model is developed, which is solved using a kinetic Monte Carlo algorithm. The model describes the structure and growth of planar PAH molecules, and is referred to as the kinetic Monte Carlo-aromatic site (KMC-ARS) model. A detailed PAH growth mechanism based on reactions at radical sites available in the literature, and additional reactions obtained from quantum chemistry calculations are used to model the PAH growth processes. New rates for the reactions involved in the cyclodehydrogenation process for the formation of 6-member rings on PAHs are calculated in this work based on density functional theory simulations. The KMC-ARS model is validated by comparing experimentally observed ensembles on PAHs with the computed ensembles for a C{sub 2}H{sub 2} and a C{sub 6}H{sub 6} flame at different heights above the burner. The motivation for this model is the development of a detailed soot particle population balance model which describes the evolution of an ensemble of soot particles based on their PAH structure. However, at present incorporating such a detailed model into a population balance is computationally unfeasible. Therefore, a simpler model referred to as the site-counting model has been developed, which replaces the structural information of the PAH molecules by their functional groups augmented with statistical closure expressions. This closure is obtained from the KMC-ARS model, which is used to develop correlations and statistics in different flame environments which describe such PAH structural information. These correlations and statistics are implemented in the site-counting model, and results from the site-counting model and the KMC-ARS model are in good agreement. Additionally the effect of steric hindrance in large PAH structures is investigated and correlations for sites unavailable for reaction are presented. (author)

Raj, Abhijeet; Celnik, Matthew; Shirley, Raphael; Sander, Markus; Patterson, Robert; West, Richard; Kraft, Markus [Department of Chemical Engineering, Cambridge University, New Museums Site, Pembroke Street, Cambridge CB2 3RA (United Kingdom)

2009-04-15

349

Particle/vapor concentrations and distributions of PAHs in the atmosphere of southern Chesapeake Bay  

SciTech Connect

Atmospheric PAH concentrations were measured at four sites characterized as rural (Haven Beach), semiurban (York River), urban (Hampton), and industrialized (Elizabeth River) areas as part of a study to quantify gaseous exchange fluxes across the air-water interface of southern Chesapeake Bay. Aerosol particle-associated PAH concentrations were similar at all sites; however, PAH vapor concentrations in the urban areas were as much as a factor of 50 greater than those at the rural site. Mean total PAH concentrations ranged from 7.87 ng/m{sup 3} at the rural site to 92.8 ng/m{sup 3} at the urban site. Daily total PAH concentrations ranged from 1.60 to 198 ng/m{sup 3}. Exponential increases in PAH vapor concentrations with temperature were observed at the non-rural sites, suggesting volatilization from contaminated surfaces during warmer weather; whereas PAH vapor concentrations at the rural Haven Beach site exhibited little seasonal variability. Aerosol particle-associated PAH levels were similar at all sites and increased in winter due to the temperature dependence of vapor-particle partitioning, increased sources from combustion of fossil fuel and wood for home heating, and cold condensation of source vapors to background aerosols as air masses are dispersed to remote regions. Plots of log K{sub d} vs. log P{sub sat,SC1} indicate PAH partitioning is not at equilibrium in rural areas of Southern Chesapeake Bay. In addition, plots of log K{sub d} vs. 1/T for individual PAHs indicate difference particle characteristics or partitioning processes influence particle/vapor distributions at the urban and rural sites.

Gustafson, K.E. [Univ. of West Florida, Pensacola, FL (United States). Inst. for Coastal and Estuarine Research; Dickhut, R.M. [Coll. of William and Mary, Gloucester Point, VA (United States)

1995-12-31

350

Polycyclic aromatic hydrocarbons (PAHs) in Antarctic Martian meteorites, carbonaceous chondrites, and polar ice  

NASA Astrophysics Data System (ADS)

Recent analyses of the carbonate globules present in the Martian meteorite ALH84001 have detected polycyclic aromatic hydrocarbons (PAHs) at the ppm level (McKay et al., 1996). The distribution of PAHs observed in ALH84001 was interpreted as being inconsistent with a terrestrial origin and were claimed to be indigenous to the meteorite, perhaps derived from an ancient martian biota. We have examined PAHs in the Antarctic shergottite EETA79001, which is also considered to be from Mars, as well as several Antarctic carbonaceous chondrites. We have found that many of the same PAHs detected in the ALH84001 carbonate globules are present in Antarctic carbonaceous chondrites and in both the matrix and carbonate (druse) component of EETA79001. We also investigated PAHs in polar ice and found that carbonate is an effective scavenger of PAHs in ice meltwater. Moreover, the distribution of PAHs in the carbonate extract of Antarctic Allan Hills ice is remarkably similar to that found in both EETA79001 and ALH84001. The reported presence of L-amino acids of apparent terrestrial origin in the EETA79001 druse material (McDonald and Bada, 1995) suggests that this meteorite is contaminated with terrestrial organics probably derived from Antarctic ice meltwater that had percolated through the meteorite. Our data suggests that the PAHs observed in both ALH84001 and EETA79001 are derived from either the exogenous delivery of organics to Mars or extraterrestrial and terrestrial PAHs present in the ice meltwater or, more likely, from a mixture of these sources. It would appear that PAHs are not useful biomarkers in the search for extinct or extant life on Mars.

Becker, Luann; Glavin, Daniel P.; Bada, Jeffrey L.

1997-01-01

351

Polycyclic aromatic hydrocarbons (PAHs) in Antarctic Martian meteorites, carbonaceous chondrites, and polar ice  

NASA Astrophysics Data System (ADS)

Recent analyses of the carbonate globules present in the Martian meteorite ALH84001 have detected polycyclic aromatic hydrocarbons (PAHs) at the ppm level. The distribution of PAHs observed in ALH84001 was interpreted as being inconsistent with a terrestrial origin and were claimed to be indigenous to the meteorite, perhaps derived from an ancient martian biota. We have examined PAHs in the Antarctic shergottite EETA79001, which is also considered to be from Mars, as well as several Antarctic carbonaceous chondrites. We have found that many of the same PAHs detected in the ALH84001 carbonate globules are present in Antarctic carbonaceous chondrites and in both the matrix and carbonate (druse) component of EETA79001. We also investigated PAHs in polar ice and found that carbonate is an effective scavenger of PAHs in ice meltwater. Moreover, the distribution of PAHs in the carbonate extract of Antarctic Allan Hills ice is remarkably similar to that found in both EETA79001 and ALH84001. The reported presence of L-amino acids of apparent terrestrial origin in the EETA79001 druse material suggests that this meteorite is contaminated with terrestrial organics probably derived from Antarctic ice meltwater that had percolated through the meteorite. Our data suggests that the PAHs observed in both ALH84001 and EETA79001 are derived from either the exogenous delivery of organics to Mars or extraterrestrial and terrestrial PAHs present in the ice meltwater or, more likely, from a mixture of these sources. It would appear that PAHs are not useful biomarkers in the search for extinct or extant life in Mars.

Becker, Luann; Glavin, Daniel P.; Bada, Jeffrey L.

1997-07-01

352

Impact of vehicular traffic emissions on particulate-bound PAHs: Levels and associated health risks  

NASA Astrophysics Data System (ADS)

Considering vehicular transport as one of the most health-relevant emission sources of urban air, and with aim to further understand its negative impact on human health, the objective of this work was to study its influence on levels of particulate-bound PAHs and to evaluate associated health risks. The 16 PAHs considered by USEPA as priority pollutants, and dibenzo[a,l]pyrene associated with fine (PM2.5) and coarse (PM2.5-10) particles were determined. The samples were collected at one urban site, as well as at a reference place for comparison. The results showed that the air of the urban site was more seriously polluted than at the reference one, with total concentrations of 17 PAHs being 2240% and 640% higher for PM2.5 and PM2.5-10, respectively; vehicular traffic was the major emission source at the urban site. PAHs were predominantly associated with PM2.5 (83% to 94% of ?PAHs at urban and reference site, respectively) with 5 rings PAHs being the most abundant groups of compounds at both sites. The risks associated with exposure to particulate PAHs were evaluated using the TEF approach. The estimated value of lifetime lung cancer risks exceeded the health-based guideline levels, thus demonstrating that exposure to PM2.5-bound PAHs at levels found at urban site might cause potential health risks. Furthermore, the results showed that evaluation of benzo[a]pyrene (regarded as a marker of the genotoxic and carcinogenic PAHs) alone would probably underestimate the carcinogenic potential of the studied PAH mixtures.

Slezakova, Klara; Castro, Dionísia; Delerue–Matos, Cristina; Alvim–Ferraz, Maria da Conceição; Morais, Simone; Pereira, Maria do Carmo

2013-06-01

353

Spectroscopy of neutral and ionized PAHs. From laboratory studies to astronomical observations  

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 astrochemistry is to reproduce (in a realistic way) the physical conditions that are associated with the emission and 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. PAHs, neutrals and ions, are expanded through a pulsed discharge nozzle (PDN) and probed with high-sensitivity cavity ringdown spectroscopy (CRDS). These laboratory experiments provide unique information on the spectra of free, cold large carbon molecules and ions in the gas phase from the ultraviolet and visible range to the near-infrared 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 of interstellar and circumstellar environments will also be discussed.

Salama, Farid

2005-01-01

354

METABOLIC ACTIVATION PATHWAYS OF CYCLOPENTA-FUSED PAH (POLYCYCLIC AROMATIC HYDROCARBONS) AND THEIR RELATIONSHIP TO GENETIC AND CARCINOGENIC ACTIVITY  

EPA Science Inventory

Cyclopenta-fused PAH are a novel class of environmental PAH of which the most well known example is cyclopenta(cd)pyrene. The fusion of an unsaturated cyclopenta-ring on a PAH in general, markedly enhances its activity as a gene mutagen in bacteria and cultured mammalian cells, a...

355

ATTRIBUTION OF PARTICLE EXPOSURE AND RISK TO COMBUSTION SOURCE EMISSIONS BASED ON PERSONAL PAH EXPOSURE AND URINARY METABOLITES  

EPA Science Inventory

Personal airborne exposures to carcinogenic particulate PAH have been significantly correlated with exposure to respirable fine particle mass (PM 2.5) in several studies. All combustion sources emit PAH, however the relative concentrations of different PAH and other organic tr...

356

Bioremediation of an aged polycyclic aromatic hydrocarbons (PAHs)-contaminated soil by filamentous fungi isolated from the soil  

Microsoft Academic Search

Twenty-one filamentous fungi were isolated from the soil of an old polycyclic aromatic hydrocarbon (PAH)-contaminated gaswork site and tested in their native soil for PAH degradation. This degradation study was performed for each isolate with two inoculation treatments, by spore or mycelial inoculum. An improvement in the extent of total PAH degradation occurred with mycelial inoculum. The greatest degradation was

Olivier Potin; Catherine Rafin; Etienne Veignie

2004-01-01

357

Use of an avoidance test for the assessment of microbial degradation of PAHs1 Christine Lors1  

E-print Network

1 Use of an avoidance test for the assessment of microbial degradation of PAHs1 2 Christine Lors1 (50%). PAH disappearance was linked to10 the occurrence of indigenous microbiota able to degrade springtail Folsomia candida was used to assess3 changes in contamination levels at low doses of PAHs

Paris-Sud XI, Université de

358

Biokinetic parameter estimation for ISB of PAH-contaminated soil  

SciTech Connect

In situ bioremediation (ISB) has been shown to be an effective and cost-efficient method for remediating contaminated ground water and soil. One of the major disadvantages associated with this process is the lack of available kinetic information. The viability of respirometry to determine the relevant biokinetic parameters for degradation of contaminants in groundwater has been proven; however, little work has been done using soil systems. This work investigated the applicability of using respirometer data to determine the biokinetic parameters for soil systems. The specific soil investigated was contaminated with polycyclic aromatic hydrocarbons (PAHs), which contain 16 EPA priority pollutants. The work also investigated a logarithmic growth and modified Lineweaver-Burke approach for experimentally determining the maximum specific growth rate from batch degradation data. As expected, this research concluded that determining all biokinetic parameters from respirometer data was not a viable method for soil systems. Obtaining the maximum specific growth rate from batch degradation data provided more accurate results.

Smith, K.; Cutright, T.; Qammar, H.

2000-04-01

359

Particulate PAH emissions from residential biomass combustion: time-resolved analysis with aerosol mass spectrometry.  

PubMed

Time-resolved emissions of particulate polycyclic aromatic hydrocarbons (PAHs) and total organic particulate matter (OA) from a wood log stove and an adjusted pellet stove were investigated with high-resolution time-of-flight aerosol mass spectrometry (AMS). The highest OA emissions were found during the addition of log wood on glowing embers, that is, slow burning pyrolysis conditions. These emissions contained about 1% PAHs (of OA). The highest PAH emissions were found during fast burning under hot air starved combustion conditions, in both stoves. In the latter case, PAHs contributed up to 40% of OA, likely due to thermal degradation of other condensable species. The distribution of PAHs was also shifted toward larger molecules in these emissions. AMS signals attributed to PAHs were found at molecular weights up to 600 Da. The vacuum aerodynamic size distribution was found to be bimodal with a smaller mode (Dva ? 200 nm) dominating under hot air starved combustion and a larger sized mode dominating under slow burning pyrolysis (Dva ? 600 nm). Simultaneous reduction of PAHs, OA and total particulate matter from residential biomass combustion may prove to be a challenge for environmental legislation efforts as these classes of emissions are elevated at different combustion conditions. PMID:24866381

Eriksson, A C; Nordin, E Z; Nyström, R; Pettersson, E; Swietlicki, E; Bergvall, C; Westerholm, R; Boman, C; Pagels, J H

2014-06-17

360

Polycyclic aromatic hydrocarbons (PAHs) in starfish body and bottom sediments in Mohang Harbor (Taean), South Korea.  

PubMed

The concentrations of 27 polycyclic aromatic hydrocarbons (PAHs) were determined in bottom sediments and starfish from Mohang Harbor (MH) in Taean peninsula, South Korea. In December 2007, crude oil washed ashore from the M/V Hebei Spirit and was subsequently cleaned up within a few months of the incident. The ecological risk, bioaccumulation factor (BAF), and composition of the 27 PAHs were examined. The PAH concentrations in the bottom sediment ranged from 24 to 366 ?g/kg dried weight, and the ecological risk was determined as minimal (mERL-Q?PAH concentrations in Asterina pectinifera (inside seawall) and Asterias amurensis (outside seawall) were 1,226 and 1,477 ?g/kg dry weight (d.w.), respectively. The total BAFs (?BAF) for A. amurensis was 3.8 times higher than that of A. pectinifera, and the PAH concentrations of 5-6 log K OW were highest in the two starfish species. Further, PAH fingerprint analysis (nine alkyl-substituted PAHs fraction, low molecular weight (LMW)/high molecular weight (HMW), Phe/Ant, and Flu/Pyr), and principal component analysis (PCA) based on three crude oil samples from the M/V Hebei Spirit showed no remaining influence of crude oil. PMID:24682639

Kim, Chang Joon; Hong, Gi Hoon; Kim, Hye Eun; Yang, Dong Beom

2014-07-01

361

Characterization of polycyclic aromatic hydrocarbons (PAHs) on lime spray dryer (LSD) ash using different extraction methods.  

PubMed

In this study, traditional Soxhlet, automatic Soxhlet and ultrasonic extraction techniques were employed to determine the speciation and concentration of polycyclic aromatic hydrocarbons (PAHs) on lime spray dryer (LSD) ash samples collected from the baghouse of a spreader stoker boiler. To test the efficiencies of different extraction methods, LSD ash samples were doped with a mixture of 16 US EPA specified PAHs to measure the matrix spike recoveries. The results showed that the spike recoveries of PAHs were different using these three extraction methods with dichloromethane (DCM) as the solvent. Traditional Soxhlet extraction achieved slightly higher recoveries than automatic Soxhlet and ultrasonic extraction. Different solvents including toluene, DCM:acetone (1:1 V/V) and hexane:acetone (1:1 V/V) were further examined to optimize the recovery using ultrasonic extraction. Toluene achieved the highest spike recoveries of PAHs at a spike level of 10 microg kg(-1). When the spike level was increased to 50 microg kg(-1), the spike recoveries of PAHs also correspondingly increased. Although the type and concentration of PAHs detected on LSD ash samples by different extraction methods varied, the concentration of each detected PAH was consistently low, at microg kg(-1) levels. PMID:15990154

Sun, Ping; Weavers, Linda K; Taerakul, Panuwat; Walker, Harold W

2006-01-01

362

Quantification of PAHs and health risk via ingestion of vegetable in Khyber Pakhtunkhwa Province, Pakistan.  

PubMed

This study was conducted to evaluate the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in the soil and vegetable irrigated with wastewater in 11 districts of Khyber Pakhtunkhwa (KPK) Province (Pakistan). The ?16PAH ranged from 223 to 929?g/kg in the soils with highest concentration in the soil of high urbanized district (Peshawar), while the lowest concentration in the soil of less urbanized district (Lakki Marwat). PAH concentrations in vegetable ranged from 51.6 to 402?g/kg on dry weight bases (d.w). Naphthaene, phenanthrene, fluoranthene and pyrene were frequently observed in vegetable. The concentrations of higher molecular weight PAHs were lower in vegetable as compared to low molecular weight PAHs. The highest PAH concentrations were observed in leafy vegetable (lettuce>spinach). The highest TEQ value (7.2) was observed for pyrene following by naphthalene (4.9) for the samples collected from Mardan, while the lowest mean TEQ value (0.12) was found for acenaphthylene followed by benzo[k]fluoranthene (0.26) in Peshawar. The highest TEQ value was 4.1 for flouranthene followed by 3.8 for naphthalene in the KPK province. The uniqueness of this study is the quantification of PAHs in the soil and vegetable collected from a large area of KPK Province which are rapidly urbanizing. PMID:25150739

Waqas, Muhammad; Khan, Sardar; Chao, Cai; Shamshad, Isha; Qamar, Zahir; Khan, Kifayatullah

2014-11-01

363

Emission of polycyclic aromatic hydrocarbons (PAHs) from the liquid injection incineration of petrochemical industrial wastewater.  

PubMed

This study investigated the emission of polycyclic aromatic hydrocarbons (PAHs) from stack flue gas and air pollution control device (APCD) effluent of the liquid injection incinerator (LII) disposing the petrochemical industrial wastewater, and PAH removal efficiencies of wet electrostatic precipitator (WESP) and wet scrubber (WSB). The PAH carcinogenic potency were investigated with the benzo(a)pyrene equivalent concentration (BaP(eq)). The remarkably high total-BaP(eq) concentration (220 microgNm(-3)) in the stack flue gas was much higher than those of several published emission sources, and indicated the possible influence on its surrounding environment. The total-PAH emission factors of the WESP, WSB and stack flue gas were 78.9, 95.7 and 30,900 microgL(-1) wastewater, respectively. The removal efficiencies of total-PAHs were 0.254, 0.309 and 0.563% for WESP, WSB and overall, respectively, suggesting that the use of both WESP and WSB shows insignificant PAH removal efficiencies, and 99.4% of total-PAHs was directly emitted to the ambient air through the stack flue gas. This finding suggested that the better incineration efficiencies, and APCD removal efficiencies for disposing the petrochemical industrial wastewater are necessary in future. PMID:17368715

Wang, Lin-Chi; Wang, I-Ching; Chang, Juu-En; Lai, Soon-Onn; Chang-Chien, Guo-Ping

2007-09-01

364

Tourmaline combined with Phanerochaete chrysosporium to remediate agricultural soil contaminated with PAHs and OCPs.  

PubMed

The potential application on tourmaline was explored. The combination of tourmaline and Phanerochaete chrysosporium was conducted to remediate the field soil from the Dagu Drainage River bank of Tianjin in China. The total PAH and OCP concentrations in the soil were 6.4±0.05 and 145.9±1.9mg/kg, respectively. During the 60 day remediation program, the remediation degradation rates of all the 16 U.S. EPA priority PAHs and OCPs were 53.2±4.7% and 43.5±3.1%, respectively. The PAH and OCP removal rates were 31.9±2.9% and 26.4±1.8%, respectively, in soil with the addition of tourmaline, and the removal rates were 40.5±2.3% and 34.2±3.9%, respectively, in soil with the addition of P. chrysosporium. Thus, the combination of tourmaline and P. chrysosporium promoted the bioremediation rate of PAHs and OCPs in the soil, compared with the rates obtained using tourmaline or P. chrysosporium individually for the remediation of PAH and OCP degradation. In addition, tourmaline can promote the generation of soil hydrogen peroxidase and invertase enzyme, significantly increase the indigenous bacterial community and the number of PAH and OCP-degraders compared to those in the control, and reduce the soil humic acid content. Hence, the present study provides a potential alternative for the remediation of soils contaminated by PAHs and OCPs. PMID:24333677

Wang, Cuiping; Yu, Li; Zhang, Zhiyuan; Wang, Baolin; Sun, Hongwen

2014-01-15

365

Particle size distribution and PAH concentrations of incense smoke in a combustion chamber.  

PubMed

The particle size distribution and the concentrations of polycyclic aromatic hydrocarbons (PAHs) in incense smoke were studied using a custom-designed combustion chamber. Among the nine types of incense investigated, the particle and the total PAH emission factors varied significantly. The average mass median aerodynamic diameter (MMAD) of the smoke aerosol was 262+/-49nm, which positively correlated to particle emission factor (mg/stick, p<0.05). Coagulation was a major mechanism that dictates the MMAD of the smoke. The total toxic equivalency (the sum of the benzo[a]pyrene equivalent concentration) of the solid-phase PAHs (S-PAHs) was over 40 times higher than that of the corresponding gas-phase PAHs, indicating that the S-PAHs in incense smoke may pose potential health risk. Experiments show that each lowered percentage of total carbon content in the raw incense helped decrease the particle emission factor by 2.6mg/g-incense, and the reduction of S-PAH emission factor ranged from 8.7 to 26% when the carbon content was lowered from 45 to 40%. PMID:17014940

Yang, Chi-Ru; Lin, Ta-Chang; Chang, Feng-Hsiang

2007-01-01

366

Preliminary study on PAH degradation by bacteria from contaminated sediments in Xiamen Western Sea, Fujian, China  

NASA Astrophysics Data System (ADS)

In order to estimate the biodegradation of three polycyclic aromatic hydrocarbons (PAHs) compounds, bacterial strains were isolated from marine sediments in three heavily contaminated sites (Yuandang Lake, Dongdu Port and Aquacultural zones in Maluan Bay) in Xiamen Western Sea. The results show three bacterial strains, which used pyrene as the sole carbon source, were identified as strains of Aureobacterium sp., Arthrobacter sp., Rhodococcus sp. The PAH-degrading bacteria isolated had a strong ability to degrade phenanhrene, fluoranthene and pyrene at different degradation rates. The highest degradation rate was observed when three PAH compounds were mixed with an individual strain in the medium. The three PAHs were degraded after one week with a degradation rate of 89.94% for phenanthrene and 93.4% for both of fluoranthene and pyrene. In addition, after 25 days of incubation, the degradation rate was 99.98% for phenanthrene and 99.97% for both of fluoranthene and pyrene. Optical density was measured to estimate bacterial growth during the degradation of PAHs. Highest levels of bacterial growth were observed with a three PAH mixture in the culture, suggesting that the concentration of PAHs influenced bacterial growth and the highest levels of degradation for most series were detected after one week of incubation.

Khalid, Maskaoui; Zheng, Tianling; Hong, Huasheng; Yu, Zhiming; Yuan, Jianjun; Hu, Zhong

2004-12-01

367

Spatio-temporal distribution and characteristics of PAHs in sediments from Masan Bay, Korea.  

PubMed

The distribution of polycyclic aromatic hydrocarbons (PAHs) has been investigated in the surface and core sediments from Masan Bay, Korea. Total PAHs in the surface sediments ranged from 207 to 2670 ng/g dry weight with a mean value of 680 ng/g. Qualitative similarity and quantitative difference between inner and outer bay indicate that the main sources of PAHs are located in the inner bay and outer bay is also affected by the same sources. Vertical distribution of PAHs revealed that three distinctive stages could be differentiated with the help of PCA analysis. The highest concentration (industrialization stage) appeared between late 1950s and 1980, which was 10 years later than other developed countries. A strong pyrolytic source fingerprint has been detected with slight influence of petrogenic sources, and diagenetic PAH, perylene also contributed. Total organic carbon normalized PAHs (sum of 13 PAHs, 8.85-88.0 microg/g OC) were under the threshold effects concentration (TEC, 290 microg/g OC). PMID:15757695

Yim, U H; Hong, S H; Shim, W J; Oh, J R; Chang, M

2005-03-01

368

Role of CYP1B1 in PAH-DNA adduct formation and breast cancer risk  

SciTech Connect

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 water, and diet. PAHs require metabolic transformation to bind to DNA, causing DNA adducts, which can lead to mutations and are thought to be an important pre-cancer marker. In breast tissue, PAHs appear to be metabolized to their cancer-causing form primarily by the cytochrome P450 enzyme CYP1B1. Because the genotoxic impact of PAH depends on their metabolism, we hypothesized that high CYP1B1 enzyme levels result in increased formation of PAH-DNA adducts in breast tissue, leading to increased development of breast cancer. We have investigated molecular mechanisms of the relationship between PAH exposure, CYP1B1 expression and breast cancer risk in a clinic-based case-control study. We collected histologically normal breast tissue from 56 women (43 cases and 13 controls) undergoing breast surgery and analyzed these specimens for CYP1B1 genotype, PAH-DNA adducts and CYP1B1 gene expression. We did not detect any difference in aromatic DNA adduct levels of cases and controls, only between smokers and non-smokers. CYP1B1 transcript levels were slightly lower in controls than cases, but the difference was not statistically significant. We found no correlation between the levels of CYP1B1 expression and DNA adducts. If CYP1B1 has any role in breast cancer etiology it might be through its metabolism of estrogen rather than its metabolism of PAHs. However, due to the lack of statistical power these results should be interpreted with caution.

Goth-Goldstein, Regine; Russell, Marion L.; Muller, A.P.; Caleffi, M.; Eschiletti, J.; Graudenz, M.; Sohn, Michael D.

2010-04-01

369

Tubule urate and PAH transport: sensitivity and specificity of serum protein inhibition  

SciTech Connect

Macromolecules in rabbit serum inhibit the cellular uptake and transepithelial secretion of (/sup 14/C)urate and p-(/sup 3/H)aminohippurate ((/sup 3/H)PAH) in rabbit S/sub 2/ proximal tubule segments. To understand better the potential role these inhibitors may have in the regulation of renal organic anion excretion, the authors examined the specificity and relative inhibitory effects on tubule urate and PAH transport of albumin and ..gamma..-globulin, the major inhibitory proteins in rabbit serum. Native rabbit serum markedly inhibited the cellular accumulation or urate and PAH by isolated nonperfused segments. Urate and PAH transport was also inhibited by bovine serum, human serum, Cohn-fractionated rabbit albumin, and rabbit ..gamma..-globulin, but not by Cohn-fractionated bovine serum albumin. ..cap alpha..-Lactalbumin and ..beta..-lactoglobulin, derived from milk, also inhibited urate and PAH transport, but to a lesser extent than albumin and ..gamma..-globulin. The transport inhibitory effects of proteins were independent of their binding to urate and PAH. Unidirectional influx and the steady-state intracellular accumulation of urate and PAH in suspensions of proximal tubules were decreased by rabbit serum proteins, suggesting that these inhibitors act on the external face of the cells to diminish the uptake of the organic anions. These studies indicate that the principal plasma proteins (albumin and ..gamma..-globulin) significantly inhibit urate and PAH transporters in the basolateral membranes of S/sub 2/ proximal tubules. They suggest that circulating plasma proteins that can penetrate the basement membrane of proximal tubules may directly modulate the renal excretion of urate and PAH.

Grantham, J.J.; Kennedy, J.; Cowley, B.

1987-04-01

370

Desorption and Bioavailability of PAHs in Contaminated Soil Subjected to Long-Term In Situ Biostimulation  

PubMed Central

The distribution and potential bioavailability of polycyclic aromatic hydrocarbons (PAHs) in soil from a former manufactured-gas plant (MGP) site were examined before and after long-term biostimulation under simulated in situ conditions. Treated soil was collected from the oxygenated zones of two continuous-flow columns, one subjected to biostimulation and the other serving as a control, and separated into low- and high-density fractions. In the original soil, over 50% of the total PAH mass was associated with lower-density particles, which comprised < 2% of the total soil mass. However, desorbable fractions of PAHs were much lower in the low-density material than in the high-density material. After over 500 d of biostimulation, significant removal of total PAHs occurred in both the high- and low-density materials (77% and 53%, respectively), with three- and four-ring PAHs accounting for the majority of the observed mass loss. Total PAHs that desorbed over a 28-d period were substantially lower in treated soil from the biostimulated column than in the original soil for both the high-density material (23 versus 63%) and low-density material (5 versus 20%). The fast-desorbing fractions quantified by a two-site desorption model ranged from 0.1 to 0.5 for most PAHs in the original soil but were essentially zero in the biostimulated soil. The fast-desorbing fractions in the original soil underestimated the extent of PAH biodegradation observed in the biostimulated column, and thus was not a good predictor of PAH bioavailability after long-term, simulated in situ biostimulation. PMID:21932296

Richardson, Stephen D.; Aitken, Michael D.

2011-01-01

371

Spitzer IRAC Color Diagnostics for Extended Emission in Star Forming Regions  

E-print Network

The infrared data from the Spitzer Space Telescope has provided an invaluable tool for identifying physical processes in star formation. In this study we calculate the IRAC color space of UV fluorescent molecular hydrogen (H$_2$) and Polycyclic Aromatic Hydrocarbon (PAH) emission in photodissociation regions (PDRs) using the Cloudy code with PAH opacities from Draine & Li 2007. We create a set of color diagnostics that can be applied to study the structure of PDRs and to distinguish between FUV excited and shock excited H$_2$ emission. To test this method we apply these diagnostics to Spitzer IRAC data of NGC 2316. Our analysis of the structure of the PDR is consistent with previous studies of the region. In addition to UV excited emission, we identify shocked gas that may be part of an outflow originating from the cluster.

Ybarra, Jason E; Román-Zúñiga, Carlos G; Lada, Elizabeth A

2014-01-01

372

Spitzer IRAC Color Diagnostics for Extended Emission in Star-forming Regions  

NASA Astrophysics Data System (ADS)

The infrared data from the Spitzer Space Telescope are an invaluable tool for identifying physical processes in star formation. In this study, we calculate the Infrared Array Camera (IRAC) color space of UV fluorescent H2 and polycyclic aromatic hydrocarbon (PAH) emission in photodissociation regions (PDRs) using the Cloudy code with PAH opacities from Draine & Li. We create a set of color diagnostics that can be applied to study the structure of PDRs and to distinguish between FUV-excited and shock-excited H2 emission. To test this method, we apply these diagnostics to Spitzer IRAC data of NGC 2316. Our analysis of the structure of the PDR is consistent with previous studies of the region. In addition to UV excited emission, we identify shocked gas that may be part of an outflow originating from the cluster.

Ybarra, Jason E.; Tapia, Mauricio; Román-Zúñiga, Carlos G.; Lada, Elizabeth A.

2014-10-01

373

Diagnostic Diagram with polycyclic aromatic hydrocarbons in different types of galaxies  

NASA Astrophysics Data System (ADS)

In this contribution, we investigate the energetic processes associated to star formation activity in galaxies. In this way, spectroscopic data was used to discriminate those processes in a sample of starburst, luminous infrared galaxies-LIRGs, ultraluminous infrared galaxies-ULIRGs, and also in Seyfert, quasars and radio galaxies. We propose a new diagnostic diagram based on the polycyclic aromatic hydrocarbon features. The diagnostic diagram allow us to discriminate the behavior of starbursts and LIRGs-ULIRGs objects, taking into account the line emission of the PAHs, [NeII], [NeIII], and [OIV]. We found a good relation between [NeII] and PAH (11.2? m+11.3? m) in starburst, LINER and Seyfert samples.

Quintero, S.; Ramos P., A. F.; Higuera-G., M. A.; Martínez-Galarza, J. R.

2014-10-01

374

Total and bioavailable PAH concentrations in biochar - a future soil improver  

NASA Astrophysics Data System (ADS)

Biochar is pyrolyzed organic feedstock. It has become more and more important as soil conditioner and received broad attention as a possible measure against climate change. Polycyclic aromatic hydrocarbons (PAHs) are formed during biochar production due to incomplete combustion. These PAHs will enter the environment when the biochar is applied as soil conditioner to avoid leaching of nutrients, to increase microbial biomass and activity, to remediate the soil of organic pollutants, etc. Such positive effects are undermined if PAH exposure is concomitantly increased. We have determined the total PAH concentrations of about 40 commercially produced biochars with an analytical method based on Soxhlet extraction with toluene optimized in our laboratory (Hilber et al.). The bioavailability of the PAHs in these biochars was assessed with polyoxymethylene (POM), a passive sampler, which measures the truly dissolved concentration of organic pollutants in the pore water, according to Hale et al. Samples from total and POM extractions where measured by GC-MS to determine the total and bioavailable concentrations of the 16 EPA PAHs, respectively. Preliminary results showed that the total concentrations of the biochars ranged from 0.4 to 355 mg?16 EPA PAH/kgBC. The bioavailable concentrations were in the nanograms per liter for the ?16 EPA PAH and goes in line with findings of recently published data of Hale et al. The fraction desorbed by POM in relation to the total concentrations is in the permill range. Although the bioavailable concentration appears very small, it has to be considered that biochars might be applied to an agricultural field several times. Thus, the source of amended PAHs to the soil is renewed not only for the bioavailable but also for the total concentration. Biochar applications might become a problem especially for legislation accounting for total concentrations. The only guideline for biochars is from the International Biochar Initiative which set the maximum allowed threshold value at 6 mg?16 EPA PAH/kgBC. Efforts of the producers to minimize the PAH concentrations towards or below this value as well as effects of the biochar's treatment as for example composting after pyrolysis or ozonation will be discussed in this study. Further, the bioavailable PAH will be considered under different aspects such as the fingerprints and compared with findings from other researchers.

Hilber, I.; Blum, F.; Hale, S.; Cornelissen, G.; Schmidt, H. P.; Bucheli, T. D.

2012-04-01

375

Ratios and Proportions  

NSDL National Science Digital Library

In this learning object from Wisc-Online, students will examine ratios and proportions. The unit's activities include defining ratios and proportions, simplifying ratios, solving problems using proportions and answering practice questions.

Blohowiak, Chad; Jensen, Douglas; Reed, Allen

2005-01-01

376

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

SciTech Connect

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 species. To examine the modes of PAH action in the light and determine if the photomodified compounds are hazardous, the authors investigated the photoinduced toxicity of anthracene, phenanthrene and benzo[a]pyrene to the aquatic higher plant Lemna gibba (a duckweed). Toxicity end points were inhibition of growth and extent of chlorosis. Light did indeed activated the phytotoxicity of PAHs, with UV radiation more effective than visible light. Dose-response curves based on chemical concentration and light intensity revealed the order of phytotoxic strength to be anthracene > phenanthrene > benzo[a]pyrene. To explore whether photomodified PAHs were contributing to toxicity, the chemicals were irradiated before toxicity testing. The rates of photomodification of the three PAHs were rapid, and the relative velocities were coincident with the order of toxic strength. Furthermore, the photomodified PAHs were more hazardous to Lemna than the intact compounds. Because interpretations of the potential impacts of PAHs in the environment are based mostly on measurements of the structurally intact chemicals, the severity of PAH hazards is possibly underestimated.

Xiaodong Huang; Dixon, D.G.; Greenberg, B.M. (Univ., of Waterloo, Ontario (Canada). Dept. of Biology)

1993-06-01

377

Polycyclic aromatic hydrocarbons (PAHs) in surface sediments from the Bizerte Lagoon, Tunisia: levels, sources, and toxicological significance.  

PubMed

To assess the status of polycyclic aromatic hydrocarbon (PAH) contamination in sediments from the Bizerte Lagoon (northern Tunisia), 18 surface sediment samples were collected in March 2011 and analyzed for 14 US Environmental Protection Agency priority PAHs by high-performance liquid chromatography. The total concentrations of the 14 PAHs (?PAHs) ranged from 16.9 to 394.1 ng g(-1) dry weight (dw) with a mean concentration of 85.5 ng g(-1) dw. Compared with other lagoons, coasts, and bays in the world, the concentrations of PAHs in surface sediments of the Bizerte Lagoon are low to moderate. The PAHs' composition pattern was dominated by the presence of four-ring PAHs (45.8 %) followed by five-ring (26.8 %) and three-ring PAHs (12.7 %). The PAH source analysis suggested that the main origin of PAHs in the sediments of the lagoon was mainly from pyrolytic sources. According to the numerical effect-based sediment quality guidelines of the USA, the levels of PAHs in the Bizerte Lagoon should not exert adverse biological effects. The total benzo[a]pyrene toxicity equivalent values calculated for the samples varied from 3.1 to 53.7 ng g(-1) dw with an average of 10.6 ng g(-1) dw. PMID:24346349

Barhoumi, Badreddine; LeMenach, Karyn; Devier, Marie-Hélène; Ben Ameur, Walid; Etcheber, Henry; Budzinski, Hélène; Cachot, Jérôme; Driss, Mohamed Ridha

2014-05-01

378

Distribution and partitioning of polycyclic aromatic hydrocarbons (PAHs) in different size fractions in sediments from Boston Harbor, United States.  

PubMed

The concentrations of 16 US EPA priority pollutant polycyclic aromatic hydrocarbons (PAHs) were analyzed in four size fractions (< 62, 62-125, 125-250, and > 250 microm) in three contaminated Boston Harbor sediments. Total PAH concentrations ranged from 7.3 to 358 microg/g dry wt. and varied largely among the different size fractions in these sediments. For all three sites, the highest PAH concentrations were associated with the large size (> 250 microm) fractions while the fine silt and clay fractions (< 62 microm) contained relatively low PAHs. Despite the great concentration differences, the composition of PAHs in the four size fractions of these sediments showed similar patterns dominated by PAHs with three or more rings. By examining the distribution patterns of selected alkyl homologs to parent compounds, the results indicate that the major PAHs contributing to the high contamination in the inner harbor sediments were from pyrogenic sources. A positive correlation between PAHs and sedimentary organic carbon exists for all size fractions in the sediments. Calculated organic carbon normalized partition coefficients (log K(oc)) for selected major PAHs indicate near-equilibrium partitioning of PAHs among the different size fractions despite their large concentration variations. Sedimentary organic matter associated with different size fractions was the controlling factor for the observed distribution differences of PAHs among the size fractions. Our results also suggest that sedimentary organic matter with different origins and maturities may have somewhat different PAH sorption characteristics. Particulate organic matter of charcoal, plant detritus and Capitella fecal pellets in the sediments appear to sorb PAHs more strongly than organic matter associated with clay minerals. The strong association of PAHs with these organic particles in sediments will have a great influence not only on their distribution but also on long-term environmental impact. PMID:11763227

Wang, X C; Zhang, Y X; Chen, R F

2001-11-01

379

Urinary polycyclic aromatic hydrocarbons as a biomarker of exposure to PAHs in air: a pilot study among pregnant women.  

PubMed

Recent studies have linked increased polycyclic aromatic hydrocarbons (PAHs) in air and adverse fetal health outcomes. Urinary PAH metabolites are of interest for exposure assessment if they can predict PAHs in air. We investigated exposure to PAHs by collecting air and urine samples among pregnant women pre-selected as living in "high" (downtown and close to steel mills, n=9) and "low" (suburban, n=10) exposure areas. We analyzed first-morning urine voids from all 3 trimesters of pregnancy for urinary PAH metabolites and compared these to personal air PAH/PM(2.5)/NO(2)/NO(X) samples collected in the 3rd trimester. We also evaluated activities and home characteristics, geographic indicators and outdoor central site PM(2.5)/NO(2)/NO(X) (all trimesters). Personal air exposures to the lighter molecular weight (MW) PAHs were linked to indoor sources (candles and incense), whereas the heavier PAHs were related to outdoor sources. Geometric means of all personal air measurements were higher in the "high" exposure group. We suggest that centrally monitored heavier MW PAHs could be used to predict personal exposures for heavier PAHs only. Urine metabolites were only directly correlated with their parent air PAHs for phenanthrene (Pearson's r=0.31-0.45) and fluorene (r=0.37-0.58). Predictive models suggest that specific metabolites (3-hydroyxyfluorene and 3-hydroxyphenanthrene) may be related to their parent air PAH exposures. The metabolite 2-hydroxynaphthalene was linked to smoking and the metabolite 1-hydroxypyrene was linked to dietary exposures. For researchers interested in predicting exposure to airborne lighter MW PAHs using urinary PAH metabolites, we propose that hydroxyfluorene and hydroxyphenanthrene metabolites be considered. PMID:21915154

Nethery, Elizabeth; Wheeler, Amanda J; Fisher, Mandy; Sjödin, Andreas; Li, Zheng; Romanoff, Lovisa C; Foster, Warren; Arbuckle, Tye E

2012-01-01

380

Effect of photoionization of PAH molecules on the heating of HI interstellar gas  

NASA Astrophysics Data System (ADS)

It is proposed that the photoelectric effect on polycyclic aromatic hydrocarbons (PAH) molecules can be the dominant source of heating of the interstellar H I gas, if their photoionization cross-section is sufficient. Such a quantity has not yet been measured for large PAHs, but is estimated from data on benzene. The ionization properties of PAHs are reviewed and their ionization fraction in various environments are computed. The heat input from the ejected photoelectrons is calculated, and it can be the dominant heating source for the H I clouds and the intercloud medium if about 10 percent of the cosmic carbon is locked in PAH molecules. Such a value is consistent with previous estimates of their abundance. This situation differs from the photoelectric effect on grains, which has been pointed out to be inefficient in the hot intercloud medium.

D'Hendecourt, L. B.; Leger, A.

1987-06-01

381

Isolation and genetic identification of PAH degrading bacteria from a microbial consortium.  

PubMed

Polycyclic aromatic hydrocarbons (PAH; naphthalene, anthracene and phenanthrene) degrading microbial consortium C2PL05 was obtained from a sandy soil chronically exposed to petroleum products, collected from a petrochemical complex in Puertollano (Ciudad Real, Spain). The consortium C2PL05 was highly efficient degrading completely naphthalene, phenanthrene and anthracene in around 18 days of cultivation. The toxicity (Microtox method) generated by the PAH and by the intermediate metabolites was reduced to levels close to non-toxic in almost 40 days of cultivation. The identified bacteria from the contaminated soil belonged to gamma-proteobacteria and could be include in Enterobacter and Pseudomonas genus. DGGE analysis revealed uncultured Stenotrophomonas ribotypes as a possible PAH degrader in the microbial consortium. The present work shows the potential use of these microorganisms and the total consortium for the bioremediation of PAH polluted areas since the biodegradation of these chemicals takes place along with a significant decrease in toxicity. PMID:19468841

Molina, M Carmen; González, Natalia; Bautista, L Fernando; Sanz, Raquel; Simarro, Raquel; Sánchez, Irene; Sanz, José L

2009-11-01

382

AN OVERVIEW OF THE DEVELOPMENT, STATUS, AND APPLICATION OF EQUILIBRIUM PARTITIONING SEDIMENT BENCHMARKS FOR PAH MIXTURES  

EPA Science Inventory

This article provides an overview of the development, theoretical basis, regulatory status, and application of the U.S. Environmental Protection Agency's (USEPA's)< Equilibrium Partitioning Sediment Benchmarks (ESBs) for PAH mixtures. ESBs are compared to other sediment quality g...

383

Polycyclic aromatic hydrocarbon (PAH) in four fish species from different trophic levels in the Persian Gulf.  

PubMed

Concentration of ten polycyclic aromatic hydrocarbon (PAH) compounds were determined in liver of four fish species from different trophic levels (Aurigequula fasciata, omnivore; Alepes djedaba, carnivore; Liza abu and Sardinella albella, phytoplanktivores). In all the species, similar distributions were observed in which pyrene predominated and followed by naphthalene and acenaphthylene. L. abu accumulated the highest concentration of ?PAH, followed by S. albella, A. fasciata, and A. djedaba. No correlation between PAH content in fish liver and fish size has been found at the level of individual compounds, except for benzo[a]pyrene (p?PAH concentrations than male in all the species, except for L. abu. PMID:25004856

Rahmanpour, Shirin; Farzaneh Ghorghani, Nasrin; Lotfi Ashtiyani, Seyede Masoumeh

2014-11-01

384

MOBILIZATION OF PAHS AND PCBS FROM IN-PLACE CONTAMINATED MARINE SEDIMENTS DURING SIMULATED RESUSPENSION EVENTS  

EPA Science Inventory

A particle entrainment simulator was used to experimentally produce representative estuarine resuspension conditions to investigate the resulting transport of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) to the overlying water column. Contaminants ...

385

STUDIES ON IN-SITU BIOREMEDIATION OF PAH CONTAMINATED SEDIMENTS: BIOAVAILABILITY, BIODEGRADABILITY AND TOXICITY ISSUES  

EPA Science Inventory

The widespread contamination of aquatic sediments by polycyclic aromatic hydrocarbons (PAHs) has created a need for cost-effective bioremediation processes. The purpose of this research was to compare the toxicity reduction achieved through several sediment treatments. Sediments ...

386

Direct quantification of PAHs in biomass burning aerosols by desorption electrospray ionization mass spectrometry  

NASA Astrophysics Data System (ADS)

Desorption electrospray ionization mass spectrometry (DESI-MS) technique was applied to the quantitative analysis of polycyclic aromatic hydrocarbons (PAHs) in biomass burning aerosols. Experimental conditions were optimized to enhance the detection efficiencies of PAHs. DESI-MS signal intensities showed good linear responses to the amount of PAHs in a dynamic range of four orders of magnitude and the detection limit is about 1 pg/mm2. Mass concentrations of three-, four-, five-, six-ring PAHs in laboratory-made rice straw burning aerosols were directly measured by DESI-MS without any sample pretreatment. The results agree well with the parallel measurement by traditional GC-MS. DESI phenomenon was also observed for other compounds in biomass burning aerosols such as sugars, inorganic and organic acids. Potential applications of DESI-MS to the rapid analysis of multiple components in aerosol samples were discussed.

Li, Mei; Chen, Hong; Wang, Bi-Fei; Yang, Xin; Lian, Jin-Jun; Chen, Jian-Min

2009-03-01

387

Occurrence and distribution of polycyclic aromatic hydrocarbons (PAHs) in Bolgoda and Beira Lakes, Sri Lanka.  

PubMed

The pollution of polycyclic aromatic hydrocarbons (PAHs) has been widely used to assess the potential impact of anthropogenic activities on aquatic environments because their occurrence in water is closely tied to urban activities. Many PAHs possess mutagenic and carcinogenic properties (Menzie et al. 1992). PAH distribution and toxic potentials have therefore been the focus of numerous studies in waterways including the Great Lakes (USEPA Report 1994), Yanisei Bay (Dahle et al., 2003), and the Fraser River basin (Yunker et al., 2002). Sri Lanka, a small island nation with a dense population of about 20 million people, faces a multitude of environmental stresses ranging from deforestation to traffic congestion and the deterioration of water quality. This study was undertaken to understand the occurrence, sources, and potential impacts of PAHs in the waterways of Sri Lanka. Two lakes, Beira and Bolgoda, were selected for the study due to their economic value and high level of pollution. Beira Lake, situated in downtown Colombo, the capital city of Sri Lanka, is highly polluted. Sources of pollution are multifarious. For instance, clusters of communities have sprung up along the edges of the lake in recent times and many shacks have been built. These communities are generally not connected to municipal sewer systems and substantial quantities of domestic sewage and untreated wastewaters are discharged directly into the lake. Small industries have also grown rapidly around the lakes, most of which are not believed to have adequate facilities to treat industrial wastewater, especially organic wastes. In addition, Sri Lanka has experienced an upsurge of motor vehicles, including millions of three-wheelers and minivans that are powered by leaded gasoline and diesel fuels. Traffic congestion and severe air pollution due to vehicle emissions are now common daily occurrences and are considered a major potential source of PAHs in the lakes. Although Bolgoda Lake is situated some distance from Colombo, it is heavily polluted due to the growing number of towns with an attendant increase in small businesses and various industries along its shores. These new developments have undoubtedly impacted the lake through the discharge of PAHs and other anthropogenic chemicals present in industrial wastewater and from street runoffs. The lake, additionally, receives a large quantity of pollutants from the industrial zone in the north. The pollution caused by PAHs has led to various studies on the distribution and origin of PAHs in the environment (Yunker et al., 1996; Budzinski et al., 1997). Based on the proportions of different PAHs, most studies aim to distinguish PAHs of petrogenic sources from those of pyrolytic origins. The PAHs of petrogenic origin, prevalent in coals and fossil fuels, are formed from diagenesis of sedimentary organic material under low to moderate temperature and tend to consist of low-molecular-weight PAHs with two to three aromatic rings (Potter et al., 1998). The pyrolytic PAHs, on the other hand, are formed at much higher temperatures (greater than 500 degrees C for example) and consist mainly of four or more aromatic rings (Commins, 1969). Thus, an increase in the proportion of higher-molecular-weight PAHs is taken to be indicative of contaminations of mainly pyrolytic origin. The prevalence of high-molecular-weight PAHs in the urban dusts (Wise et al., 1988) and in atmospheric particles (Sicre et al., 1987) illustrates the chemistry of their formation at high temperature. The purpose of this study was to determine the PAH concentrations and distribution with respect to sampling location, origin and sources in two polluted lakes. PMID:17522750

Pathiratne, K A S; De Silva, O C P; Hehemann, David; Atkinson, Ian; Wei, Robert

2007-08-01

388

The role of the charge state of PAHs in ultraviolet extinction  

E-print Network

Aims: We explore the relation between charge state of polycyclic aromatic hydrocarbons (PAHs) and extinction curve morphology. Methods: We fit extinction curves with a dust model including core-mantle spherical particles of mixed chemical composition (silicate core, $sp^2$ and $sp^3$ carbonaceous layers), and an additional molecular component. We use exact methods to calculate the extinction due to classical particles and accurate computed absorption spectra of PAHs in different charge states, for the contribution due to the molecular component, along a sample of five rather different lines of sight. Results: A combination of classical dust particles and mixtures of real PAHs satisfactorily matches the observed interstellar extinction curves. Variations of the spectral properties of PAHs in different charge states produce changes consistent with the varying relative strengths of the bump and non-linear far-UV rise.

C. Cecchi-Pestellini; G. Malloci; G. Mulas; C. Joblin; D. A. Williams

2008-04-24

389

GEOCHEMISTRY OF PAHS IN AQUATIC ENVIRONMENTS: A SYNTHESIS OF DISTRIBUTION, SOURCE, PERSISTENCE, PARTITIONING AND BIOAVAILABILITY  

EPA Science Inventory

On the basis of their distributions, sources, persistence, partitioning and bioavailability, polycyclic aromatic hydrocarbons (PAHs) are a unique class of persistent organic pollutants (POPs) contaminating the aquatic environment. They are of particular interest to geochemists an...