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1

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

PubMed

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

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

2012-01-01

2

PAH molecular diagnostic ratios applied to atmospheric sources: a critical evaluation using two decades of source inventory and air concentration data from the UK.  

PubMed

Molecular diagnostic ratios (MDRs)-the ratios of defined pairs of individual compounds-have been widely used as markers of different source categories of polycyclic aromatic hydrocarbons (PAHs). However, it is well-known that variations in combustion conditions and environmental degradation processes can cause substantial variability in the emission and degradation of individual compounds, potentially undermining the application of MDRs as reliable source apportionment tools. The United Kingdom produces a national inventory of atmospheric emissions of PAHs, and has an ambient air monitoring program at a range of rural, semirural, urban, and industrial sites. The inventory and the monitoring data are available over the past 20 years (1990-2010), a time frame that has seen known changes in combustion type and source. Here we assess 5 MDRs that have been used in the literature as source markers. We examine the spatial and temporal variability in the ratios and consider whether they are responsive to known differences in source strength and types between sites (on rural-urban gradients) and to underlying changes in national emissions since 1990. We conclude that the use of these 5 MDRs produces contradictory results and that they do not respond to known differences (in time and space) in atmospheric emission sources. For example, at a site near a motorway and far from other evident emission sources, the use of MDRs suggests "non-traffic" emissions. The ANT/(ANT + PHE) ratio is strongly seasonal at some sites; it is the most susceptible MDR to atmospheric processes, so these results illustrate how weathering in the environment will undermine the effectiveness of MDRs as markers of source(s). We conclude that PAH MDRs can exhibit spatial and temporal differences, but they are not valid markers of known differences in source categories and type. Atmospheric sources of PAHs in the UK are probably not dominated by any single clear and strong source type, so the mixture of PAHs in air is quickly "blended" away from the influence of the few major point sources which exist and further weathered in the environment by atmospheric reactions and selective loss processes. PMID:21859122

Katsoyiannis, Athanasios; Sweetman, Andrew J; Jones, Kevin C

2011-10-15

3

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

4

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

5

Model-based evaluation of the use of polycyclic aromatic hydrocarbons molecular diagnostic ratios as a source identification tool.  

PubMed

Polycyclic Aromatic Hydrocarbons (PAHs) molecular diagnostic ratios (MDRs) are unitless concentration ratios of pair-PAHs with the same molecular weight (MW); MDRs have long been used as a tool for PAHs source identification purposes. In the present paper, the efficiency of the MDR methodology is evaluated through the use of a multimedia fate model, the calculation of characteristic travel distances (CTD) and the estimation of air concentrations for individual PAHs as a function of distance from an initial point source. The results show that PAHs with the same MW are sometimes characterized by substantially different CTDs and therefore their air concentrations and hence MDRs are predicted to change as the distance from the original source increases. From the assessed pair-PAHs, the biggest CTD difference is seen for Fluoranthene (107 km) vs. Pyrene (26 km). This study provides a strong indication that MDRs are of limited use as a source identification tool. PMID:24140981

Katsoyiannis, Athanasios; Breivik, Knut

2014-01-01

6

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

7

Optimal sampling ratios in comparative diagnostic trials  

PubMed Central

Summary A subjective sampling ratio between the case and the control groups is not always an efficient choice to maximize the power or to minimize the total required sample size in comparative diagnostic trials.We derive explicit expressions for an optimal sampling ratio based on a common variance structure shared by several existing summary statistics of the receiver operating characteristic curve. We propose a two-stage procedure to estimate adaptively the optimal ratio without pilot data. We investigate the properties of the proposed method through theoretical proofs, extensive simulation studies and a real example in cancer diagnostic studies. PMID:24948841

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

2014-01-01

8

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

PubMed

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

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

2012-04-01

9

Development of novel fuel ion ratio diagnostic techniques.  

PubMed

To overcome the challenge of measuring the fuel ion ratio in the core (?<0.3) of ITER, a coordinated effort aiming at developing diagnostic techniques has been initiated. The investigated techniques are novel uses or further development of existing methods such as charge exchange recombination spectrometry, neutron spectrometry, and collective Thomson scattering. An overview of the work on the three diagnostic techniques is presented. PMID:21033847

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

2010-10-01

10

The diagnostic odds ratio: a single indicator of test performance  

Microsoft Academic Search

Diagnostic testing can be used to discriminate subjects with a target disorder from subjects without it. Several indicators of diagnostic performance have been proposed, such as sensitivity and specificity. Using paired indicators can be a disadvantage in comparing the performance of competing tests, especially if one test does not outperform the other on both indicators. Here we propose the use

Afina S. Glas; Jeroen G. Lijmer; Martin H. Prins; Gouke J. Bonsel; Patrick M. M. Bossuyt

2003-01-01

11

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. PMID:25170522

2014-01-01

12

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

PubMed

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

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

2014-07-15

13

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

E-print Network

everywhere in the world, including water, sediment/soil, air, and organisms (Harvey, 1997). PAHs can be formed by either thermal alteration of buried organic matter or incomplete combustion of organic matter (Suess, 1976; Sims and Overcash, 1983; Nikolaou... stability of larger ring numbers, especially for linearly fused PAHs (Harvey, 1997). Most complex PAHs are named by the IUPAC system of nomenclature. PAH compound with complex ring systems use the name of the base component rings and adds...

Kim, Moon Koo

2004-11-15

14

Baseline distributions and sources of Polycyclic Aromatic Hydrocarbons (PAHs) in the surface sediments from the Prai and Malacca Rivers, Peninsular Malaysia.  

PubMed

In this study, the surface sediments of the Malacca and Prai Rivers were analyzed to identify the distributions, and sources of Polycyclic Aromatic Hydrocarbons (PAHs). The total PAH concentrations varied from 716 to 1210 and 1102 to 7938 ng g(-1)dw in the sediments of the Malacca and Prai Rivers, respectively. The PAH concentrations can be classified as moderate and high level of pollution in the sediments of the Malacca and Prai Rivers, respectively. The comparison of PAHs with the Sediment Quality Guidelines (SQGs) indicates that the PAHs in the sediments of the Malacca and Prai Rivers may have the potential to cause adverse toxicity effects on the sampled ecosystems. The diagnostic ratios of individual PAHs indicate both petrogenic- and pyrogenic-origin PAHs with dominance of pyrogenic source in both rivers. These findings demonstrate that the environmental regulations in Malaysia have effectively reduced the input of petrogenic petroleum hydrocarbons into rivers. PMID:25173594

Keshavarzifard, Mehrzad; Zakaria, Mohamad Pauzi; Hwai, Tan Shau; Yusuff, Ferdius Ferdius Mohamat; Mustafa, Shuhaimi; Vaezzadeh, Vahab; Magam, Sami M; Masood, Najat; Alkhadher, Sadeq A A; Abootalebi-Jahromi, Fatemeh

2014-11-15

15

PAH and Dust Processing in Supernova Remnants  

NASA Astrophysics Data System (ADS)

I present observations of shock-processed PAHs and dust in supernova remnants (SNRs). Supernova shocks are one of the primary sites destroying, fragmenting and altering interstellar PAHs and dust. Studies of PAHs through supernova shocks had been limited because of confusion with PAHs in background emission. Spitzer observations with high sensitivity and resolution allow us to separate PAHs associated with the SNRs and unrelated, Galactic PAHs. In the young SNR N132D, PAH features are detected with a higher PAH ratio of 15-20/7.7 ?m than those of other astronomical objects, and we suggest large PAHs have survived behind the shock. We present the spectra of additional 14 SNRs observed with Spitzer IRS and MIPS SED covering the range of 5-90 ?m. Bright PAH features from 6.2 to 15-20 ?m are detected from many of SNRs which emit molecular hydrogen lines, indicating that both large and small PAHs survive in low velocity shocks. We observe a strong correlation between PAH detection and carbonaceous small grains, while a few SNRs with dominant silicate dust lack PAH features. We characterize PAHs depending on the shock velocity, preshock density and temperature of hot gas, and discuss PAH and dust processing in shocks and implication of PAH and dust cycles in ISM.

Rho, J.; Andersen, M.; Tappe, A.; Reach, W. T.; Bernard, J. P.; Hewitt, J.

2011-03-01

16

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

PubMed

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

Sun, Li; Zang, Shuying

2013-09-01

17

Revisited abundance diagnostics in quasars: Fe II/Mg II ratios  

E-print Network

Both the Fe II UV emission in the 2000- 3000 A region [Fe II (UV)] and resonance emission line complex of Mg II at 2800 A are prominent features in quasar spectra. The observed Fe II UV/ Mg II emission ratios have been proposed as means to measure the buildup of the Fe abundance relative to that of the alpha-elements C, N, O, Ne and Mg as a function of redshift. The current observed ratios show large scatter and no obvious dependence on redshift. Thus, it remains unresolved whether a dependence on redshift exists and whether the observed Fe II UV/ Mg II ratios represent a real nucleosynthesis diagnostic. We have used our new 830-level model atom for Fe+ in photoionization calculations, reproducing the physical conditions in the broad line regions of quasars. This modeling reveals that interpretations of high values of Fe II UV/ Mg II are sensitive not only to Fe and Mg abundance, but also to other factors such as microturbulence, density, and properties of the radiation field. We find that the Fe II UV/ Mg II ratio combined with Fe II (UV)/ Fe II (Optical) emission ratio, where Fe II (Optical) denotes Fe II emission in 4000 - 6000 A can be used as a reliable nucleosynthesis diagnostic for the Fe/Mg abundance ratios for the physical conditions relevant to the broad-line regions (BLRs) of quasars. This has extreme importance for quasar observations with the Hubble Space Telescope and also with the future James Webb Space Telescope.

E. Verner; F. Bruhweiler; D. Verner; S. Johansson; T. Gull

2003-06-25

18

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

19

Characterization of PM(10) fraction of road dust for polycyclic aromatic hydrocarbons (PAHs) from Anshan, China.  

PubMed

Nineteen road dust samples were collected during 2005 in different parts of the urban area of Anshan, Liaoning Province, China, and 11 polycyclic aromatic hydrocarbons (PAHs) species were quantitatively analyzed using GC-MS. The results indicated that the total average concentration of PAHs over the investigated sites ranged from 48.73 to 638.26 microg/g, with a mean value of 144.25 microg/g, higher than the concentrations measured in previous studies. PAHs concentrations were higher with high molecular weight homologues (4-6 rings PAHs), accounting for 83.24-96.98%, showing combustion of petroleum fuels was a potential source. Organic carbon in road dust was considered one of the important factors that influenced the concentrations of PAHs in this study, and it was found that concentrations of total PAHs were correlated with those of organic carbon in road dust. The results of diagnostic ratios analysis showed traffic emission (gasoline or diesel) was one of the most important sources of road dust PAHs. Principal component analysis (PCA) indicated that the major sources of road dust PAHs might be emission from traffic, steel industry, cooking and coal combustion. PMID:19539426

Han, Bin; Bai, Zhipeng; Guo, Guanghuan; Wang, Fang; Li, Fu; Liu, Qiuxin; Ji, Yaqin; Li, Xiang; Hu, Yandi

2009-10-30

20

Century-Long Source Apportionment of PAHs in Athabasca Oil Sands Region Lakes Using Diagnostic Ratios and Compound-Specific  

E-print Network

, and Martine M. Savard INRS Eau Terre Environnement, Quebec, QC, G1K 9A9, Canada Geological Survey of Canada, Natural Resources Canada, Quebec, QC, G1K 9A9, Canada *S Supporting Information ABSTRACT: Evaluating on the surrounding boreal forest ecosystem requires a rigorous approach to source discrimination. This study presents

Beaudoin, Georges

21

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

PubMed

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

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

2014-07-01

22

Serum ?1?-glycoprotein and afamin ratio as potential diagnostic and prognostic markers in cholangiocarcinoma.  

PubMed

Cholangiocarcinoma (CCA) affects the intra- and extrahepatic bile ducts and is commonly burdened by a late presentation and resulting high mortality rate. Accordingly, finding non-invasive biomarkers with adequate diagnostic/prognostic values is a priority in high-risk populations. In this study, we analyzed proteomes of serum samples from six CCA cases and ten healthy subjects using two-dimensional polyacrylamide gel electrophoresis to identify CCA-associated spots. Thirty-six CCA-associated proteins found in sera were identified by mass spectrometry. ?1?-Glycoprotein (A1BG) and afamin (AFM) were detected consistently at different degrees in CCA sera compared with controls and were validated for their diagnostic and prognostic potential in a larger cohort of 64 patients with CCA, 4 with benign biliary diseases and 20 healthy subjects and compared between pre- and postsurgery serum samples from 26 CCA patients to ascertain a prognostic correlation. A single blot test developed to assess the serum A1BG/AFM ratio could detect CCA cases with 87.5% specificity, 84.4% sensitivity and the levels were significantly higher in CCA compared with controls. A high level of postoperative serum A1BG/AFM ratio was associated with worse outcomes and the infiltration of resection margins. The A1BG/AFM ratio may constitute a novel non-invasive candidate marker to diagnose CCA and its outcomes with high specificity and sensitivity. Prospective studies are awaited to demonstrate the clinical value of this observation. PMID:23104505

Tolek, Arthit; Wongkham, Chaisiri; Proungvitaya, Siriporn; Silsirivanit, Atit; Roytrakul, Sittiruk; Khuntikeo, Narong; Wongkham, Sopit

2012-10-01

23

Unusual PAH Emission in Elliptical Galaxies  

E-print Network

In a sample of thirty normal elliptical galaxies observed with the Spitzer IRS, one galaxy, NGC4697, shows strong PAH emission, but with an apparently weak 7.7 micron feature. We find that the PAH emission is confined to the central regions of the galaxy and that once a quiescent elliptical galaxy spectrum is subtracted, the PAH feature ratios are normal. We show that the PAH spectrum resembles the diffuse ISM of our galaxy rather than an HII region, and is not indicative of a starburst galaxy. We suggest that the PAHs in NGC4697 are consistent with a recent but now past burst of star formation.

J. D. Bregman; J. N. Bregman; P. Temi

2006-04-18

24

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

25

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

26

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

27

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

28

PAHs in Translucent Interstellar Clouds  

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

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

Multimedia model for polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs in Lake Michigan.  

PubMed

Polycyclic aromatic hydrocarbon (PAH) contamination in the U.S. Great Lakes has long been of concern, but information regarding the current sources, distribution, and fate of PAH contamination is lacking, and very little information exists for the potentially more toxic nitro-derivatives of PAHs (NPAHs). This study uses fugacity, food web, and Monte Carlo models to examine 16 PAHs and five NPAHs in Lake Michigan, and to derive PAH and NPAH emission estimates. Good agreement was found between predicted and measured PAH concentrations in air, but concentrations in water and sediment were generally under-predicted, possibly due to incorrect parameter estimates for degradation rates, discharges to water, or inputs from tributaries. The food web model matched measurements of heavier PAHs (?5 rings) in lake trout, but lighter PAHs (?4 rings) were overpredicted, possibly due to overestimates of metabolic half-lives or gut/gill absorption efficiencies. Derived PAH emission rates peaked in the 1950s, and rates now approach those in the mid-19th century. The derived emission rates far exceed those in the source inventories, suggesting the need to reconcile differences and reduce uncertainties. Although additional measurements and physiochemical data are needed to reduce uncertainties and for validation purposes, the models illustrate the behavior of PAHs and NPAHs in Lake Michigan, and they provide useful and potentially diagnostic estimates of emission rates. PMID:25373871

Huang, Lei; Batterman, Stuart A

2014-12-01

31

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

PubMed

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

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

2013-06-01

32

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

PubMed

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

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

2014-07-15

33

Data handling of GC/MS signals for characterization of PAH sources in Northern Italy aerosols.  

PubMed

The paper describes the characterization of polycyclic aromatic hydrocarbons (PAHs) in atmospheric aerosol samples using Gas Chromatography-Mass Spectrometry analysis. A data handling of GC/MS signals based on Experimental Autocovariance Function (EACVF) is described in order to directly characterize PAHs with a simple and reliable method suitable for processing large batches of samples. The method was successfully applied to 42 aerosol samples collected in different seasons (summer, fall and winter) in two locations in Northern Italy: Milan, a large urban area, and Oasi Le Bine, a rural site. The reliability of the EACVF results was verified by comparison with the values computed with the conventional GC/MS signal treatment and the data of independent studies. Two main emission sources were identified and described by PAH concentration profiles: the road traffic source (TR), characterized by high contributions of FLNT, PYR and CHR, and the residential combustion (COMB) mainly containing pyrogenic high molecular weight PAHs, i.e., CHR, BaP, BeP, BbF and BkF. In addition, some PAH diagnostic ratios were directly computed for the EACVF plot, to distinguish between traffic and combustion dominated emissions, i.e. the ratios CHR/BaP, PYR/BaP and PYR/BeP. PMID:24468371

Pietrogrande, M C; Perrone, M G; Sangiorgi, G; Ferrero, L; Bolzacchini, E

2014-03-01

34

PAH Spectra for Everyone  

NASA Astrophysics Data System (ADS)

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

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

2007-05-01

35

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

36

Seasonal and site-specific variation in vapour and aerosol phase PAHs over Flanders (Belgium) and their relation with anthropogenic activities  

NASA Astrophysics Data System (ADS)

The concentrations of 16 US-EPA criteria polycyclic aromatic hydrocarbons (PAHs) were monitored during various seasons at six different cities/locations in the northern part of Belgium. Pressurized liquid extraction (PLE) was used for the fast recovery of PAHs from quartz fibre filters (QFFs) and polyurethane foams (PUFs) in less than 30 min with minimum solvent consumption prior to their analysis with high-performance liquid chromatography. The concentrations of PAHs varied significantly at the studied sites and showed relation to different anthropogenic activities, such as vehicular emission (diesel/gasoline), incinerator, petroleum/oil burning, coke production, and wood/coal combustion. The annual average PAH concentration ranged from 17 (at a rural site) to 114 ng m -3 (near a petroleum harbour and industry). Most of the human carcinogenic PAHs were found to be associated with suspended particulate matter, which forms around ˜55% of the total PAH levels in aerosols. Relatively higher concentrations of PAHs were detected in aerosol samples during winter compared with other seasons, whereas no clear seasonal trend was observed for the vapour phase PAHs. This fraction is likely to be more local in origin; hence, it can be used as a site-specific characteristic. The site-specific concentrations of individual PAHs were also used in diagnostic ratio evaluations and in principal component analysis to find their relation with various anthropogenic activities. These results show that the vehicular emission is a major source of PAHs in Flanders, although other anthropogenic sources, as above, have also an impact on the total PAH levels.

Ravindra, Khaiwal; Bencs, László; Wauters, Eric; de Hoog, Johan; Deutsch, Felix; Roekens, Edward; Bleux, Nico; Berghmans, Patrick; Van Grieken, René

37

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

38

Source analysis of particulate matter associated polycyclic aromatic hydrocarbons (PAHs) in an industrial city in northeastern China.  

PubMed

Particle-associated polycyclic aromatic hydrocarbon (PAH) concentrations were investigated at eight sampling sites during cold periods where heating is used (heating period) (February to March, 2005) and warm periods where heating is not required (non-heating periods) (August to September 2006) in the urban area of Anshan, an iron and steel city in northeastern China. Eleven PAH species were measured using GC-MS. The total average concentrations of PAHs ranged from 46.14 to 385.60 ng m(-3) in the heating period and from 5.28 to 146.40 ng m(-3) in the non-heating period. The lowest concentration of ?PAHs was observed at Qianshan, a monitoring site far from the city and industrial area, and the highest concentration occurred in the site located at the factory area of Anshan Iron and Steel Incorporation. Moreover, ambient PAH profiles were studied and high molecular weight PAH (including 4-6 rings) species occurred in the high fractions. Toxic equivalent factors analysis gave the potential carcinogenic risks in Anshan. For the heating sampling period, BaP equivalent concentration is in the range of 41.98 to 220.83 ng m(-3), and 9.23 to 126.00 ng m(-3) for the non-heating sampling period. By diagnostic ratio analysis, traffic emission and combustion (coal or biomass) were potential sources for PAHs in Anshan. Finally, PCA results indicated the major sources were vehicle emission, steel industry emission, and coal combustion for both heating and non-heating seasons, which agreed with the results from the diagnostic ratio analysis. PMID:21829797

Han, Bin; Ding, Xiao; Bai, Zhipeng; Kong, Shaofei; Guo, Guanghuan

2011-09-01

39

Indoor/outdoor relationships and diurnal/nocturnal variations in water-soluble ion and PAH concentrations in the atmospheric PM2.5 of a business office area in Jinan, a heavily polluted city in China  

NASA Astrophysics Data System (ADS)

Indoor/outdoor and diurnal/nocturnal variations in PM2.5 and associated water-soluble ions and polycyclic aromatic hydrocarbons (PAHs) were examined in a business office during the summer and autumn of 2010 in Jinan, China. Both indoor and outdoor PM2.5 levels were higher than the value recommended by the WHO, and outdoor sources were found to be the major contributors to indoor PM2.5. SO42-, NO3- and NH4+ were the dominant water-soluble ions in both indoor and outdoor particles. During daytime, NO3- mainly came from indoor sources, which was related to the temperature difference between the indoor and outdoor air. During daytime, the 15 monitored PAHs were all largely from indoor sources, while during nighttime, the 3 -4-ring PAHs were mainly generated indoors and the 5-6-ring PAHs predominantly came from the outdoor air. The diurnal/nocturnal variations of PAHs suggested that gas/particle partitioning driven by temperature makes a significant contribution to the variation in PAH concentrations. The diagnostic ratios revealed that biomass burning had an important contribution to outdoor PAH concentrations in autumn. The results of a risk assessment of PAH pollution suggested that indoor PAHs present more carcinogenic and mutagenic risks during daytime. Our results indicated that serious indoor air pollution in a business office presents a high health risk for workers.

Zhu, Yanhong; Yang, Lingxiao; Meng, Chuanping; Yuan, Qi; Yan, Chao; Dong, Can; Sui, Xiao; Yao, Lan; Yang, Fei; Lu, Yaling; Wang, Wenxing

2015-02-01

40

Distribution and bioaccumulation of PAHs in the UNESCO protected natural reserve of Urdaibai, Bay of Biscay.  

PubMed

Along 10 campaigns, from June 2002 to September 2004, the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) were measured in sediments and oysters (Crassostrea sp.) taken from four sites in the Unesco protected natural reserve of Urdaibai (Basque Country, Bay of Biscay). Total PAH concentration ranged from 0.7 to 140 microg kg(-1) (dw) in the case of sediments, and from 300 to 1400 microg kg(-1) (dw) in the case of oysters. During this study, the coast of the Bay of Biscay was severely affected by the Prestige oil spill (November 2002). Presumably, as a consequence of this accident, both spatial and temporal variations of the PAHs, as well as the sources of the PAHs were affected by the oil spill, and this effect was observed in the total concentrations and, especially, in several diagnostic ratios and in multivariate data analysis. Finally, both BAF (bioaccumulation factor) and BSAF (biota-sediment accumulation factor) parameters were calculated to conclude that particulate matter seems to be the most favourable uptake pathway of PAHs in oysters from this estuary. PMID:18597814

Cortazar, E; Bartolomé, L; Arrasate, S; Usobiaga, A; Raposo, J C; Zuloaga, O; Etxebarria, N

2008-08-01

41

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

PubMed

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

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

2014-08-01

42

Particulate polycyclic aromatic hydrocarbons (PAH) in the atmosphere of Bizerte city, Tunisia.  

PubMed

The particle-phase concentrations of polycyclic aromatic hydrocarbons (PAH) were determined in 13 air samples collected in an urban area of Bizerte (Tunisia) during 2009-2010. Atmospheric particulate samples were extracted by ultrasonic bath and analyzed by high-performance liquid chromatography with fluorescence detection. PAH were found in all the analyzed air samples and the most abundant compounds were pyrene, fluoranthene, benzo[g,h,i]perylene, benzo[b]fluoranthene, chrysene and benzo[a]pyrene. ?14-PAH concentrations ranging from 9.38 to 44.81 ng m(-3) with mean value of 25.39 ng m(-3). PAH diagnostic ratio source analysis revealed gasoline and diesel vehicular emissions as major sources. The mean total benzo[a]pyrene toxicity equivalent calculated for samples was 3.66 ng m(-3) and the mean contribution of the carcinogenic potency of benzo[a]pyrene was determined to be 55.8 %. Concentrations of particulate PAH in Bizerte city atmosphere were approximately eight times greater than sampled at a nearby rural site. PMID:24902648

Ben Hassine, S; Hammami, B; Ben Ameur, W; El Megdiche, Y; Barhoumi, B; Driss, M R

2014-09-01

43

Characterizing PAH emission concentrations in ambient air during a large-scale joss paper open-burning event.  

PubMed

Large-scale open burning of joss paper is an important ritual practice for deity worshipping during Buddhist and Taoist festivals. Since Buddhism and Taoism are two of the most popular religions in Chinese societies and some Asian countries, the impact of joss paper burning on the air quality needs further investigation. This study explores the concentrations of polycyclic aromatic hydrocarbons (PAHs) in ambient air during one of the most important festivals, in which large-scale burning of joss paper occurs in temples and in people's houses. The PAH concentrations were measured simultaneously at a temple site and a background site during both the festival and non-festive (ordinary) periods. Each ambient sample was extracted by the Soxhlet analytical method (for both particle-bound and gas-phase) and analyzed with gas chromatography. Experimental results indicate that the total PAH concentration during the festival period is approximately 4.2 times higher than that during the ordinary period (5384 ng m(-3) vs. 1275 ng m(-3)). This study also employed statistical methods including diagnostic ratios and principal component analysis (PCA) to identify the possible PAH emission sources. Joss paper burning and vehicular emissions are identified as the principal sources of airborne PAHs during the large-scale open-burning event. The results of this work provide useful information for public awareness concerning PAH emission from the open burning of joss paper. PMID:18207636

Lin, Min-Der; Rau, Jui-Yeh; Tseng, Hui-Hsin; Wey, Ming-Yen; Chu, Chien-Wei; Lin, Yu-Hao; Wei, Ming-Chi; Lee, Ching-Hwa

2008-08-15

44

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

PubMed

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

Choi, Sung-Deuk

2014-02-01

45

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

46

Using comprehensive GC?×?GC to study PAHs and n-alkanes associated with PM2.5 in urban atmosphere.  

PubMed

Comprehensive two-dimensional gas chromatography (GC?×?GC) utilizing a flow modulator was applied to study particulate polycyclic aromatic hydrocarbons (PAHs) and n-alkanes in the urban atmosphere. Samples were collected onto quartz fiber filters using a PM2.5 sampler at Megacity Shanghai, China. Sample preparation included extraction into n-hexane-dichloromethane mixture and cleanup on silver-impregnated silica column. Analyses were performed well with GC?×?GC-FID and GC?×?GC-TOFMS equipment. Average particulate PAHs and n-alkane concentrations were in the range of 40-100 ng/m(3) and 120-500 pg/m(3), respectively. It is alarming to note that PAHs and n-alkane concentrations were increasing with urban PM2.5 values and exceeded the air quality standards in many sampling events. Among them, 2-ring, 3-ring, and 4-ring PAHs accounted for the majority of total PAHs, and C10-15 accounted for the majority of particulate n-alkanes. Potential sources of PAHs in PM2.5 were identified using the diagnostic ratios between PAHs. Local emission sources such as combustion from gasoline and diesel engines were the main contributors of particulate-associated PAHs, while long-range transport had minor contribution to the particulate PAHs. Additionally, we determined the overall carcinogenicity of the samples based on PAH concentrations by a dose addition model and found that the overall carcinogenicity during polluted period was obviously higher than during good air quality period. PMID:25345921

Xu, Tingting; Lv, Yan; Cheng, Tiantao; Li, Xiang

2015-04-01

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

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

49

Limitations of the Odds Ratio in Gauging the Performance of a Diagnostic, Prognostic, or Screening Marker  

Microsoft Academic Search

A marker strongly associated with outcome (or disease) is often assumed to be effective for classifying persons according to their current or future outcome. However, for this assumption to be true, the associated odds ratio must be of a magnitude rarely seen in epidemiologic studies. In this paper, an illustration of the relation between odds ratios and receiver operating characteristic

Margaret Sullivan Pepe; Holly Janes; Gary Longton; Wendy Leisenring; Polly Newcomb

2004-01-01

50

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

51

Diagnostics of the molecular component of photon-dominated regions with mechanical heating. II. Line intensities and ratios  

NASA Astrophysics Data System (ADS)

CO observations in active galactic nuclei and starbursts reveal high kinetic temperatures. Those environments are thought to be very turbulent due to dynamic phenomena, such as outflows and high supernova rates. We investigate the effect of mechanical heating on atomic fine-structure and molecular lines and on their ratios. We try to use those ratios as a diagnostic to constrain the amount of mechanical heating in an object and also study its significance on estimating the H2 mass. Equilibrium photodissociation models (PDRs hereafter) were used to compute the thermal and chemical balance for the clouds. The equilibria were solved for numerically using the optimized version of the Leiden PDR-XDR code. Large velocity-gradient calculations were done as post-processing on the output of the PDR models using RADEX. High-J CO line ratios are very sensitive to mechanical heating (?mech hereafter). These emission becomes at least one order of magnitude brighter in clouds with n ~ 105 cm-3 and a star formation rate of 1 M? yr-1 (corresponding to ?mech = 2 × 10-19 erg cm-3 s-1). The emission of low-J CO lines is not as sensitive to ?mech, but they do become brighter in response to ?mech. Generally, for all of the lines we considered, ?mech increases excitation temperatures and decreases the optical depth at the line centre. Hence line ratios are also affected, strongly in some cases. Ratios involving HCN are a good diagnostic for ?mech, where the HCN(1-0)/CO(1-0) increases from 0.06 to 0.25, and the HCN(1-0)/HCO+(1-0) increase from 0.15 to 0.5 for amounts of ?mech that are equivalent to 5% of the surface heating rate. Both ratios increase to more than 1 for higher ?mech, as opposed to being much less than unity in pure PDRs. The first major conclusion is that low-J to high-J intensity ratios will yield a good estimate of the mechanical heating rate (as opposed to only low-J ratios). The second one is that the mechanical heating rate should be taken into account when determing AV or, equivalently, NH, and consequently the cloud mass. Ignoring ?mech will also lead to large errors in density and radiation field estimates. Appendices are available in electronic form at http://www.aanda.orgThe data used to generate all the grids are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/574/A127

Kazandjian, M. V.; Meijerink, R.; Pelupessy, I.; Israel, F. P.; Spaans, M.

2015-02-01

52

Molecular Spectroscopy in Astrophysics: Interstellar PAHs  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

53

Diagnostic Value of Run Chart Analysis: Using Likelihood Ratios to Compare Run Chart Rules on Simulated Data Series  

PubMed Central

Run charts are widely used in healthcare improvement, but there is little consensus on how to interpret them. The primary aim of this study was to evaluate and compare the diagnostic properties of different sets of run chart rules. A run chart is a line graph of a quality measure over time. The main purpose of the run chart is to detect process improvement or process degradation, which will turn up as non-random patterns in the distribution of data points around the median. Non-random variation may be identified by simple statistical tests including the presence of unusually long runs of data points on one side of the median or if the graph crosses the median unusually few times. However, there is no general agreement on what defines “unusually long” or “unusually few”. Other tests of questionable value are frequently used as well. Three sets of run chart rules (Anhoej, Perla, and Carey rules) have been published in peer reviewed healthcare journals, but these sets differ significantly in their sensitivity and specificity to non-random variation. In this study I investigate the diagnostic values expressed by likelihood ratios of three sets of run chart rules for detection of shifts in process performance using random data series. The study concludes that the Anhoej rules have good diagnostic properties and are superior to the Perla and the Carey rules. PMID:25799549

Anhøj, Jacob

2015-01-01

54

Monte Carlo study of grid performance in diagnostic radiology: factors which affect the selection of tube potential and grid ratio.  

PubMed

A Monte Carlo computational model has been developed for the study of the performance of anti-scatter grids in diagnostic radiology. It is used here to estimate the scatter in the image plane from soft tissue phantoms (representing the patient) and to calculate image contrast and the mean absorbed dose in the phantom. Different scattering conditions, representative of various examinations, have been investigated: adult lumbar spine; small field radiography and fluoroscopy; adult chest and paediatric pelvis and chest. For each scattering condition, the combinations of tube potential and grid ratio have been found which, for a well designed grid, result in the lowest mean absorbed dose in the phantom for a fixed contrast level. In examinations which generate large amounts of scatter, the use of high grid ratios in combination with high tube potentials is favourable with regard to both mean absorbed dose in the phantom and tube charge. When less scatter is generated, either the grid ratio or the tube potential can be varied to achieve the desired contrast level. High grid ratios require shorter exposure times, but need careful alignment in the beam to prevent primary radiation cut-off. It is shown that the air gap technique can be used to reduce patient dose in examinations with small amounts of scatter, but in combinations with a lower tube potential than when a grid is used. PMID:8293262

Sandborg, M; Dance, D R; Carlsson, G A; Persliden, J

1993-12-01

55

Ratio  

NASA Astrophysics Data System (ADS)

Effects of basicity, B (CaO:SiO2 ratio) on the thermal range, concentration, and formation mechanisms of silico-ferrite of calcium and aluminum (SFCA) and SFCA-I iron ore sinter bonding phases have been investigated using an in situ synchrotron X-ray diffraction-based methodology with subsequent Rietveld refinement-based quantitative phase analysis. SFCA and SFCA-I phases are the key bonding materials in iron ore sinter, and improved understanding of the effects of processing parameters such as basicity on their formation and decomposition may assist in improving efficiency of industrial iron ore sintering operations. Increasing basicity significantly increased the thermal range of SFCA-I, from 1363 K to 1533 K (1090 °C to 1260 °C) for a mixture with B = 2.48, to ~1339 K to 1535 K (1066 °C to 1262 °C) for a mixture with B = 3.96, and to ~1323 K to 1593 K (1050 °C to 1320 °C) at B = 4.94. Increasing basicity also increased the amount of SFCA-I formed, from 18 wt pct for the mixture with B = 2.48 to 25 wt pct for the B = 4.94 mixture. Higher basicity of the starting sinter mixture will, therefore, increase the amount of SFCA-I, considered to be more desirable of the two phases. Basicity did not appear to significantly influence the formation mechanism of SFCA-I. It did, however, affect the formation mechanism of SFCA, with the decomposition of SFCA-I coinciding with the formation of a significant amount of additional SFCA in the B = 2.48 and 3.96 mixtures but only a minor amount in the highest basicity mixture. In situ neutron diffraction enabled characterization of the behavior of magnetite after melting of SFCA produced a magnetite plus melt phase assemblage.

Webster, Nathan A. S.; Pownceby, Mark I.; Madsen, Ian C.; Studer, Andrew J.; Manuel, James R.; Kimpton, Justin A.

2014-12-01

56

Airborne particulate polycyclic aromatic hydrocarbon (PAH) pollution in a background site in the North China Plain: concentration, size distribution, toxicity and sources.  

PubMed

The size-fractionated characteristics of particulate polycyclic aromatic hydrocarbons (PAHs) were studied from January 2011 to October 2011 using a Micro-orifice Uniform Deposit Impactor (MOUDI) at the Yellow River Delta National Nature Reserve (YRDNNR), a background site located in the North China Plain. The average annual concentration of total PAHs in the YRDNNR (18.95 ± 16.51 ng/m(3)) was lower than that in the urban areas of China; however, it was much higher than that in other rural or remote sites in developed countries. The dominant PAHs, which were found in each season, were fluorene (5.93%-26.80%), phenanthrene (8.17%-26.52%), fluoranthene (15.23%-27.12%) and pyrene (9.23%-16.31%). A bimodal distribution was found for 3-ring PAHs with peaks at approximately 1.0-1.8 ?m and 3.2-5.6 ?m; however, 4-6 ring PAHs followed a nearly unimodal distribution, with the highest peak in the 1.0-1.8 ?m range. The mass median diameter (MMD) values for the total PAHs averaged 1.404, 1.467, 1.218 and 0.931 ?m in spring, summer, autumn and winter, respectively. The toxicity analysis indicated that the carcinogenic potency of particulate PAHs existed primarily in the <1.8 ?m size range. Diagnostic ratios and PCA analysis indicated that the PAHs in aerosol particles were mainly derived from coal combustion. In addition, back-trajectory calculations demonstrated that atmospheric PAHs were produced primarily by local anthropogenic sources. PMID:23921366

Zhu, Yanhong; Yang, Lingxiao; Yuan, Qi; Yan, Chao; Dong, Can; Meng, Chuanping; Sui, Xiao; Yao, Lan; Yang, Fei; Lu, Yaling; Wang, Wenxing

2014-01-01

57

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

58

Presence of PAHs in milk of industrial farms from Tizayuca, Hidalgo, Mexico.  

PubMed

The objective of this study was to determine the concentrations of polycyclic aromatic hydrocarbons (PAHs) in cow's milk from industrial farms that are located near an industrial park in Hidalgo, Mexico. It was found that the concentrations of PAHs in the raw milk of cattle from industrial farms have increased in recent years. Composite samples were collected between 2008 and 2010 and analysis carried out according to 8100 EPA procedures and analyzed by gas chromatography with FID detection. The results show that combustion PAHs were mostly Ace, Acy, and Fla (0.25, 0.32, and 0.22 µg g(-1), respectively). Diagnostic ratios were used to show that the probable sources were grass and fuel combustion. The sum of concentrations of 16 individual PAHs did not breach permissible levels in milk (25 µg g(-1) according to the United States EPA), indicating a limited health risk to animals and humans in the study area. The industrial park has adequate pollutant emission regulations. PMID:25826099

Gutiérrez, Rey; Vega, Salvador; Ortiz, Rutilio; Pérez, José Jesús; Schettino, Beatriz

2015-05-01

59

Atmospheric concentrations of PAHs, their possible sources and gas-to-particle partitioning at a residential site of Bursa, Turkey  

NASA Astrophysics Data System (ADS)

Atmospheric PAH concentrations were determined in Gulbahce district of Bursa, Turkey between August 2004 and April 2005. Measured PAH concentrations were classified as heating and non-heating season samples. The concentrations of total PAHs in heating season were almost ten times higher than those in non-heating season. Diagnostic ratios and factor analysis results show that in the heating season traffic along with residential heating emissions heavily influence PAH concentrations. The plot of log Kp versus log PL0 for all the data set of heating and non-heating season samples gave significantly different slopes. The slope for the heating season samples (- 0.92) was steeper than the one for the non-heating season samples (- 0.78). The partitioning results for individual samples further indicated that slope values varied depending on air parcel trajectories. Air parcels traveled over water (either over the Black Sea or Aegean Sea) prior to arriving at the sampling site had less steep slopes. Partitioning of PAHs was also investigated by comparing experimentally determined Kp values with the results obtained both from octanol-based model ( Kp(Oct.)) and soot and octanol-based model ( Kp (Soot + Oct.)). Both models were useful in predicting the experimental Kp values. However, they did not explain the observed variability in the experimental Kp values.

Esen, Fatma; Tasdemir, Yücel; Vardar, Nedim

60

Occurrence, distribution, sources and toxic potential of polycyclic aromatic hydrocarbons (PAHs) in surface soils from the Kumasi Metropolis, Ghana.  

PubMed

As a developing country, the economic and population growth rates in Ghana over the past few years have seen a tremendous increase. The growing rate of industrialization is gradually leading to contamination and deterioration of the environment and pollution is likely to reach disturbing levels. Surface soil samples were collected randomly from 36 communities in the Kumasi Metropolis, Ghana, to determine the concentrations, distribution, sources and toxic potential of emission of polycyclic aromatic hydrocarbons (PAHs) since no such comprehensive study had been conducted. The mean concentration of total PAHs in the surface soils in each community ranged from 14.78 at Ahinsan to 2084 ng/g dry weight at Adum with an average of 442.5 ± 527.2 ng/g dry weight. Diagnostic ratios and chemical mass balance models of the results showed that PAHs in surface soil samples from the study area were mainly from fuel combustion. Carcinogenic potency of PAH load from the city centre was approximately 150 times higher as compared to a pristine site, Kwame Nkrumah University of Science and Technology's Botanical Garden. BaP, a human carcinogen, contributed 70% of the total PAHs toxicity level from the city centre of Kumasi. PMID:25108249

Bortey-Sam, Nesta; Ikenaka, Yoshinori; Nakayama, Shouta M M; Akoto, Osei; Yohannes, Yared Beyene; Baidoo, Elvis; Mizukawa, Hazuki; Ishizuka, Mayumi

2014-10-15

61

Intact PTH Combined With the PTH Ratio for Diagnosis of Bone Turnover in Dialysis Patients: A Diagnostic Test Study  

PubMed Central

Background Determination of parathyroid hormone (PTH) is the most commonly used surrogate marker for bone turnover in stage 5 chronic kidney disease patients on dialysis (CKD-5D patients). The objective of the current study was to evaluate the predictive value of various PTH measurements for identifying low or high bone turnover rate. Study design Diagnostic test study. Settings & Participants 141 CKD-5D patients from 15 US hemodialysis centers. Index Tests Intact PTH, PTH 1–84, and PTH ratio (ratio of level of PTH 1–84 to level of large carboxy-terminal PTH fragments). Reference Test or Outcome Bone turnover determined by bone histomorphometry Other Measurements Demographic and treatment related factors, serum calcium and phosphorus. Results Histologically, patients presented with a broad range of bone turnover abnormalities. In White patients (n=70), the iPTH cut-off of >420 pg/ml resulted in classifying 84% of the patients correctly as high turnover. A PTH ratio <1.0 when added to an intact PTH <420 pg/ml increased the positive predictive value for low bone turnover from 74% to 90% in these patients. In Black patients (n=71), adding a PTH ratio <1.2 to an intact PTH <340pg/ml increased the positive predictive value for low bone turnover from 48% to 90%. Adding a PTH ratio >1.6 to an intact PTH between 340 and 790 pg/ml increased the positive predictive value for high bone turnover from 56% to 71%. Limitations Since the research protocol called for carefully controlled blood specimen handling, drawing of blood and routine specimen handling might be less stringent in clinical practice. By limiting study participation to Black and White CKD-5D patients, we cannot comment on the roles of intact PTH, PTH 1–84 and the PTH ratio in other racial/ethnic groups. Conclusion In Black CKD-5D patients, addition of the PTH ratio to intact PTH measurements is helpful for diagnosing low and high bone turnover. In White CKD-5D patients, it aids in the diagnosis of low bone turnover. PMID:20347512

Herberth, Johann; Branscum, Adam J; Mawad, Hanna; Cantor, Tom; Monier-Faugere, Marie-Claude; Malluche, Hartmut H

2010-01-01

62

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

PubMed

The determination of the fuel ion ratio n(t)/n(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(T)/n(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. PMID:21058455

Ericsson, G; Conroy, S; Gatu Johnson, M; Andersson Sundén, E; Cecconello, M; Eriksson, J; Hellesen, C; Sangaroon, S; Weiszflog, M

2010-10-01

63

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

64

Polycylcic Aromatic Hydrocarbons (PAH's) in dense cloud chemistry  

E-print Network

Virtually all detailed gas-phase models of the chemistry of dense interstellar clouds exclude polycyclic aromatic hydrocarbons (PAH's). This omission is unfortunate because from the few studies that have been done on the subject, it is known that the inclusion of PAH's can affect the gas-phase chemistry strongly. We have added PAH's to our network to determine the role they play in the chemistry of cold dense cores. In the models presented here, we include radiative attachment to form PAH-, mutual neutralization between PAH anions and small positively-charged ions, and photodetachment. We also test the sensitivity of our results to changes in the size and abundance of the PAH's. Our results confirm that the inclusion of PAH's changes many of the calculated abundances of smaller species considerably. In TMC-1, the general agreement with observations is significantly improved contrary to L134N. This may indicate a difference in PAH properties between the two regions. With the inclusion of PAH's in dense cloud chemistry, high-metal elemental abundances give a satisfactory agreement with observations. As a result, we do not need to decrease the observed elemental abundances of all metals and we do not need to vary the elemental C/O ratio in order to produce large abundances of carbon species in TMC-1 (CP).

Valentine Wakelam; Eric Herbst

2008-02-26

65

Line Ratio Diagnostics Along the Disc of Two Edge-on Lenticular Galaxies, NGC 4710 and NGC 5866  

NASA Astrophysics Data System (ADS)

We present interferometric observations of a multitude of CO lines and dense gas tracers in two nearby edge-on lenticular galaxies, NGC~4710 and NGC~5866. 12CO(1-0), 12CO(2-1), 13CO(1-0), 13CO(2-1), HCN(1-0), HCO+(1-0), HNC(1-0) ad HNCO(4-3) were detected in both galaxies. The detections of HNC(1-0) and HNCO(4-3) are presenting here for the first time in these early-types. Our observations reveal that the CO gas is much more extended compared with the dense gas tracers which are generally centrally concentrated except HCN(1-0) which was also detected in the outskirts of NGC~5866. The unique X-shape (two-component velocity distributions indicating nuclear disc and inner ring) position-velocity diagram (PVD) of these barred edge-on galaxies allows us to study integrated line intensity ratios as a function projected radius along the velocity components. We study the gas physical conditions of two-component molecular ISM, i.e. one traced by CO and one traced by HCN, HCO+, HNC and HNCO, in each velocity component separately seen on the PVD by performing line ratio diagnostics in three complementary ways. In the nuclear disc, the CO gas is gravitationally unstable, optically thinner, hotter and dense gas fraction is higher, while in the inner ring the gas is more settled, optically thick, colder and the dense gas fraction is lower. We also compare the line ratios to that obtained in the nucleus of other lenticular, spiral, seyfert, starburst and peculiar galaxies as well as that obtained in the GMCs of some other spirals/starbursts. We found that the gas in the nuclear discs of NGC~4710 and NGC~5866 has line ratios similar to that in the center of starburst galaxies while the gas in the inner rings show some differences. We finally perform non-LTE radiative transfer code to the two-component ISM using a multitude of tracers. The model results, which are agree with the empirical results, indicate that there is a factor of 2 difference in the density of the gas traced by CO and the one traced by high density tracers in the nuclear disc but average kinetic temperature is similar, while the gas in the inner ring is relatively colder and less dense compared with the gas in the nuclear disc.

Topal, Selcuk; Bureau, Martin; Davis, Timothy A.; Young, Lisa; Krips, Melanie

2015-01-01

66

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

67

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

68

Evaluating rapid diagnostic tests of intra-amniotic infection: Gram stain, amniotic fluid glucose level, and amniotic fluid to serum glucose level ratio  

Microsoft Academic Search

OBJECTIVE: The aim of the study was to compare the diagnostic utility of the Gram stain, the amniotic fluid glucose level, and the ratio of amniotic fluid glucose level to serum glucose level in detecting intra-amniotic infection.STUDY DESIGN: We conducted a prospective study of 127 patients with preterm labor and 26 patients with preterm premature rupture of the membranes (153

Michael J. Hussey; Edward S. Levy; Xavier Pombar; Peter Meyer; Howard T. Strassner

1998-01-01

69

PAH Clusters as Sources of Interstellar Infrared Emission  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbons (or PAHs) have been the subject of astrochemical research for several decades as principal sources of the interstellar aromatic infrared emission bands. PAH clusters could possibly contribute to these emission bands, but a lack of data on their infrared properties has made this hypothesis difficult to evaluate. Here we investigate homogeneous neutral PAH clusters by measuring the mid-infrared absorption spectra of the five nonlinear PAH molecules phenanthrene, chrysene, pyrene, perylene, and benzo[ghi]perylene within solid argon ice at a fixed temperature of 5 K. We attribute observed spectral shifts in their principal absorption bands as a function of argon/PAH ratio to clustering of the PAH molecules within the argon matrix. These shifts are related to the cluster structures forming in the matrix and the topology of the monomer PAH molecule. We predict that interstellar PAH molecules that are relatively large (no fewer than 50 carbon atoms per molecule) and compact will have clusters that contribute to the asymmetrically red-shaded profile of the interstellar 11.2 ?m emission band.

Roser, J. E.; Ricca, A.

2015-03-01

70

Assessing risks to adults and preschool children posed by PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) during a biomass burning episode in Northern Thailand.  

PubMed

To investigate the potential cancer risk resulting from biomass burning, polycyclic aromatic hydrocarbons (PAHs) bound to fine particles (PM2.5) were assessed in nine administrative northern provinces (NNP) of Thailand, before (N-I) and after (N-II) a haze episode. The average values of ? 3,4-ring PAHs and B[a] P Equivalent concentrations in world urban cities were significantly (p<0.05) much higher than those in samples collected from northern provinces during both sampling periods. Application of diagnostic binary ratios of PAHs underlined the predominant contribution of vehicular exhaust to PM2.5-bound PAH levels in NNP areas, even in the middle of the agricultural waste burning period. The proximity of N-I and N-II values in three-dimensional (3D) principal component analysis (PCA) plots also supports this conclusion. Although the excess cancer risk in NNP areas is much lower than those of other urban area and industrialized cities, there are nevertheless some concerns relating to adverse health impacts on preschool children due to non-dietary exposure to PAHs in home environments. PMID:25506906

Pongpiachan, Siwatt; Tipmanee, Danai; Khumsup, Chukkapong; Kittikoon, Itthipon; Hirunyatrakul, Phoosak

2015-03-01

71

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

PubMed

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

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

2014-09-15

72

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

73

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

74

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)

Aerosol 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

75

Concentrations of polycyclic aromatic hydrocarbons (PAHs) in the eggs of predatory birds in Britain.  

PubMed

The eggs of gannets from two Scottish colonies (Ailsa Craig, Bass Rock) of golden eagles from the Hebrides and Highlands and of merlin eggs from the Scottish borders were analyzed for 52 PAHs, including 2-7 ring parent and alkylated PAHs. Phenanthrene was the most abundant PAH in gannet eggs from Ailsa Craig, and methylnaphthalenes predominated in the eggs from other locations and species. Most PAHs were detected in eggs but none were at likely embryotoxic concentrations. The sum concentrations for all the PAHs analyzed (3.1-5.7 ng g(-1) wet wt.) and for the U.S. EPA 16 priority PAHs (2.0-4.3 ng g(-1) wet wt.) did not differ significantly between species or locations. This uniform, low-level accumulation suggests background exposure to diffuse sources. PCA indicated that 3 ring parent and alkylated PAHs predominated in the eggs of merlins and gannets from Ailsa Craig and Hebridean golden eagles; other eggs had a more mixed profile. Source signature diagnostics largely suggested a petrogenic origin for the PAHs in the merlin eggs that we analyzed but otherwise gave equivocal results and further work is needed to determine which diagnostics can be successfully applied to PAHs in eggs. PMID:19943681

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

2009-12-01

76

PAHs in Comets: An Overview  

E-print Network

Polycyclic aromatic hydrocarbon (PAH) molecules, ubiquitously seen in the interstellar medium (ISM) of our own and external galaxies, might have been incorporated into comets if they are formed from relatively unprocessed interstellar matter. The detection of PAHs in comets would be an important link between the ISM and comets. This review compiles our current knowledge on cometary PAHs, based on ground-based and space-borne observations of infrared vibrational and ultraviolet fluorescence spectra of comets, and laboratory analysis of interplanetary dust particles possibly of cometary origin and cometary samples returned to Earth by the Stardust spacecraft. The latter provided the most unambiguous evidence for the presence of PAHs in cometary nuclei.

Aigen Li

2008-08-29

77

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

78

Contamination of polycyclic aromatic hydrocarbons (PAHs) in surface sediments and plants of mangrove swamps in Shenzhen, China.  

PubMed

The concentrations of 16 individual and total polycyclic aromatic hydrocarbons (?PAHs) in sediments, roots and leaves of three mangrove swamps in Shenzhen, China, namely Futian, Baguang and Waterlands, were determined. The mean concentration of ?PAHs in Futian (4480 ng g(-1)) was significantly higher than that in Baguang (1262 ng g(-1)) and Waterlands (2711 ng g(-1)). Among the 16 PAHs, the concentration of naphthalene was the highest. Based on the ratios of phenanthrene/anthracene and fluoranthene/pyrene, PAHs in Futian and Waterlands came from petrogenic and pyrolytic sources, while Baguang was mainly from pyrolytic. More PAHs were accumulated in leaves, as reflected by its higher mean concentration of ?PAHs (3697 ng g(-1)) and bioconcentration factor of PAHs (BCF) (>1.5) than that in roots. The BCF values in plants collected from Futian were significantly higher than that from Waterlands. These results indicated that more attention should be paid to the PAH contamination in Futian. PMID:24631400

Li, Fenglan; Zeng, Xiaokang; Yang, Junda; Zhou, Kai; Zan, Qijie; Lei, Anping; Tam, Nora F Y

2014-08-30

79

PAH clearance after renal ischemia and reperfusion is a function of impaired expression of basolateral Oat1 and Oat3  

PubMed Central

Abstract Determination of renal plasma flow (RPF) by para?aminohippurate (PAH) clearance leads to gross underestimation of this respective parameter due to impaired renal extraction of PAH after renal ischemia and reperfusion injury. However, no mechanistic explanation for this phenomenon is available. Based on our own previous studies we hypothesized that this may be due to impairment of expression of the basolateral rate limiting organic anion transporters Oat1 and Oat3. Thus, we investigated this phenomenon in a rat model of renal ischemia and reperfusion by determining PAH clearance, PAH extraction, PAH net secretion, and the expression of rOat1 and rOat3. PAH extraction was seriously impaired after ischemia and reperfusion which led to a threefold underestimation of RPF when PAH extraction ratio was not considered. PAH extraction directly correlated with the expression of basolateral Oat1 and Oat3. Tubular PAH secretion directly correlated with PAH extraction. Consequently, our data offer an explanation for impaired renal PAH extraction by reduced expression of the rate limiting basolateral organic anion transporters Oat1 and Oat3. Moreover, we show that determination of PAH net secretion is suitable to correct PAH clearance for impaired extraction after ischemia and reperfusion in order to get valid results for RPF. PMID:24744908

Bischoff, Ariane; Bucher, Michael; Gekle, Michael; Sauvant, Christoph

2014-01-01

80

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

81

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

82

Removing PAH`s with cells on fibers  

SciTech Connect

There are over 1,500 sites contaminated with polycyclic aromatic hydrocarbons from coal gas plants. White rot fungi degrade PAH`s in soil, but the problem is to supply oxygen needed for growth of the fungus. When old cardboard boxes are buried with the fungus, oxygen is entrapped in the corrugations. A method for growing the fungus quickly is also described. Pseudomonade also degrade PAH and several strains of this bacterium have been grown on fibers. The fibers have high area, and when Celite is entrapped in the fibers, more area is provided.

Clyde, R. [Clyde Engineering, New Orleans, LA (United States)

1996-12-31

83

Spatial distribution and seasonal variation of polycyclic aromatic hydrocarbons (PAHs) contaminations in surface water from the Hun River, Northeast China.  

PubMed

The objectives of this study were to investigate the levels, dispersion patterns, seasonal variation, and sources of 16 priority polycyclic aromatic hydrocarbons (16 EPA-PAHs) in the Hun River of Liaoning Province, China. Samples of surface water were collected from upstream to downstream locations, and also from the main tributaries of the Hun River in dry period, flood period, and level period, respectively. After appropriate preparation, all samples were analyzed for 16 EPA-PAHs. Total PAHs concentrations varied from 124.55 to 439.27 ng l(-1) in surface water in dry period, 1,615.75 to 5,270.04 ng l(-1) in flood period, and 2,247.42 to 7,767.9 ng l(-1) in level period. The 16 EPA-PAHs concentrations were significantly increased in the order of level period > flood period > dry period. The composition pattern of PAHs in surface water was dominated by low molecular weight PAHs, in particular two- to three-ring PAHs. In addition, two-ring PAH accounted for 39.33 to 88.27 % of the total PAHs in level period. Low molecular weight PAHs predomination together with higher levels of PAHs in flood and level period suggested a relatively recent local source of PAHs. Special PAHs ratios such as phenanthrene/anthracene and fluoranthene/pyrene indicated that under dry weather season conditions, the PAHs found in surface water were primarily from petrogenic source, while under wet weather season conditions they were from mixed source of both petrogenic inputs and combustion sources. The comparison of PAHs contamination among different types of areas in China suggested that atmospheric depositions might be the most important approaches of PAHs into water system. Although the Hun River exists low PAHs ecological risk now, potential toxic effects will be existed in the future especially in flood and level period. PMID:22527471

Zhang, Hongling; Sun, Lina; Sun, Tieheng; Li, Huiying; Luo, Qing

2013-02-01

84

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

85

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 426.2 ng cm(-2)y(-1) in the Rezvanshahr and Anzali core sediments, respectively. Prior to 1840, four distinct maxima in PAH fluxes (61-426.2 ng cm(-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

86

Temperature-sensitive Line Ratios Diagnostics of the non-flaring Corona based on Satellite-to-Resonance Line Ratios for 1s^2-1s(np) Transitions  

NASA Astrophysics Data System (ADS)

One of the most convenient electron temperature diagnostics of hot astrophysical plasmas is the intensity ratio of dielectronic satellite lines to resonance lines in the X-ray region. Until now, this diagnostic has been applied to satellites near the 1s-2p lines of H-like ions or the 1s^2 - 1s2p lines of He-like ions, these lines being extensively observed with crystal spectrometers during flares. However, satellites near the 1s^2 - 1snp (n>2) lines of He-like ions, unlike those near the 1s^2 - 1s2p lines, have the important advantage of being well separated from their parent lines and unblended with other lines. Spectra from the RESIK spectrometer on Coronas-F, covering the wavelength range 3.4 Å,- 6.1 Å, are highly suited for observation of these satellites, due to transitions from the n = 3, 4 and 5 levels to the n = 1 level, near corresponding resonance lines of H-like and He-like Si (Si XIII, Si XIV) and S (S XV, S XVI) ions. New calculations of satellite intensity factors presented in this paper enable temperatures to be calculated from observed ratios of Li-like Si (Si XII) 1s^2 2p ^2P1/2,3/2 - 1s 2p (^3P) 3p ^2D3/2,5/2 satellite complex (5.816 Å) near He-like Si (Si XIII) 1s^2 ^1S_0 - 1s 3p ^1P_1} resonance (5.681 Å) line. These lines are well observed in recent quiet and non-flaring active region RESIK X-ray spectra, and therefore provide the most sensitive temperature diagnostic tool for physical conditions in weakly active corona.

Phillips, K. J. H.; Dubau, J.; Sylwester, J.; Sylwester, B.; Kordylewski, Z.; Culhane, J. L.; Doschek, G. A.; Lang, J.

87

Characterization and source identification of polycyclic aromatic hydrocarbons (PAHs) in river bank soils.  

PubMed

Elevated PAH concentrations were detected in bank soils along the Mosel and Saar Rivers in Germany. Information on the identification of PAH sources in this area however remains unclear. This study was able to characterize the PAH sources by application of several approaches, including consideration of the distribution patterns of 45 PAHs (including 16 EPA PAHs and some alkyl PAHs), specific PAH ratios, distribution patterns of n-alkanes and principal component analysis (PCA). In addition, the efficiency of the tested approaches was assessed. The results from the application of the various source identification methods showed that pyrogenic PAHs dominate soil samples collected upstream of the confluence of the Mosel and Saar Rivers, and petrogenic and pyrogenic PAHs dominate samples downstream of the confluence. Based on the analysis of reference materials and organic petrography, the petrogenic input was found to be dominated by coal particles. More detailed information on the petrogenic sources was provided by the n-alkane analyses. The current study concludes that to accurately determine the origin of PAHs, several identification methods must be applied. PMID:18513782

Pies, Carmen; Hoffmann, Burkhard; Petrowsky, Jelena; Yang, Yi; Ternes, Thomas A; Hofmann, Thilo

2008-08-01

88

Empirical derivation of the reference region for computing diagnostic sensitive fluorodeoxyglucose ratios in Alzheimer's disease based on the ADNI sample,  

E-print Network

fluorodeoxyglucose ratios in Alzheimer's disease based on the ADNI sample, Jerod M. Rasmussen a, , Anita Lakatos a , Steven G. Potkin a for the Alzheimer's Disease Neuroimaging Initiative a Department of Psychiatry on the dataset collected by the Alzheimer's Disease Neuroimaging Initiative (ADNI) study. Candidate reference

Kruggel, Frithjof

89

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

90

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

91

Insensitivity of Line-Ratio Diagnostics to Steady-State Non-Maxwellian Electron Distributions in Solar Corona  

NASA Technical Reports Server (NTRS)

We examine the idea that the corona is heated by a population of nonthermal particles. An upper limit on the size of the nonthermal population is derived by assuming that all of the radiation and conduction losses in the corona are provided by the nonthermal tail of the particle distribution. Only a very small percentage of nonthermal particles are allowed. These particles have a negligable effect on temperature sensitive line ratios typically observed in the EUV (Extreme Ultraviolet Radiation).

Falconer, D. A.; Davila, J. M.

1999-01-01

92

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

93

Distribution and accumulation of polycyclic aromatic hydrocarbons (PAHs) in the food web of Nansi Lake, China.  

PubMed

The concentrations of polycyclic aromatic hydrocarbons (PAHs) were analyzed in water, sediment, and biota (aquatic plant, shrimp, and fish) of Nansi Lake by gas chromatography-mass spectrometry (GC-MS). The concentrations of total PAHs were 27.54-55.04 ng L(-1) in water, 80.31-639.23 ng g(-1) dry weight (dw) in sediments, 20.92-192.78 ng g(-1) dw in aquatic plants, and 67.3-533.9 ng g(-1) dw in fish and shrimp muscles. The ratios of phenanthrene to anthracene (Ph/An), fluoranthene to pyrene (Flu/Pyr), and low molecular weight to high molecular weight (LMW/HMW) in sediment indicated that the sources of the PAHs were a mixture of pyrolytic and petrogenic contamination at most sampling sites in Nansi Lake. The composition profile of PAHs in plants was similar to that in water and animals with 2-3 ring PAHs being dominant. The 4-6 ring PAHs were the dominant PAH compounds in sediment. There is a positive correlation between sediment and aquatic plants, but their PAH composition profiles were different, implying that aquatic plant absorption of PAHs from sediment is selective and the accumulation of PAHs in aquatic plants is different. The concentration of PAHs in fish showed a positive correlation with plants, reflecting that the PAHs in fish are mainly absorbed from aquatic plants rather than directly from the water. Bioaccumulation of LMW PAHs in aquatic biota was higher than HMW PAHs. The biota-sediment accumulation factor (BSAF) values of total PAHs in the plants Potamogeton lucens Linn and Ceratophyllum demersum Linn were higher than that in most animals. The BSAF values of total PAHs in animals were in the following order: Cyprinus carpio?>?Macrobrachium nipponense?>?Carassius auratus?>?Channa argus. There was no significant relationship between PAH bioaccumulation and trophic levels in Nansi Lake. Risk assessment of PAHs in water, sediment, and animals indicated that the water environment of Nansi Lake is safe at present. It is worthwhile to note that benzo [a] anthracene (BaA), benzo [a] pyrene (BaP), indeno [1,2,3-cd] pyrene (InP), dibenz [a, h] anthracene (DBA), and benzo [ghi] perylene (BghiP) were detected in sediment, plants, and animals at all sampling sites, and they have potential carcinogenicity to the organisms of Nansi Lake. PMID:25762425

Zhang, Guizhai; Pan, Zhaoke; Wang, Xiaoming; Mo, Xiaojie; Li, Xiaoming

2015-04-01

94

Distribution of PAHs in tissues of wetland plants and the surrounding sediments in the Chongming wetland, Shanghai, China.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) concentrations were determined in sediments and three types of wetland plants collected from the intertidal flats in the Chongming wetland. The concentration of total PAHs in sediments ranged from 38.7 to 136.2 ngg(-1). Surface sediment concentrations were higher in regions with plant cover than in bare regions. Rhizome-layer sediments (56.8-102.4 ngg(-1)) contained less PAHs than surface sediments (0-5 cm). Concentrations of PAHs in plant tissues ranged from 51.9 to 181.2 ngg(-1), with highest concentrations in the leaves of Scirpus. Most of the PAHs in the leaves and other plant tissues were low molecular weight compounds (LMW, 2-4 rings), and a similar distribution pattern of PAHs in different types of plants was also observed. Source analysis indicated that plants and sediments both came from pyrogenic sources, but plants had additional petroleum contamination. The low ratio of benzo[a]anthracene over chrysene suggests that the wetland PAHs came mainly from long-distance atmospheric transportation. Significant bioaccumulation of PAHs from the sediments into plants was not observed for high molecular weight PAHs (HMW, 5-6 rings) in Chongming wetland. The small RCFs (root concentration factor from sediments) for HMW PAHs and large RCFs for LMW PAHs suggested that roots accumulated LMW PAHs selectively from sediments in Chongming wetland. PMID:22578517

Wang, Zucheng; Liu, Zhanfei; Yang, Yi; Li, Tao; Liu, Min

2012-09-01

95

Concentration and source identification of polycyclic aromatic hydrocarbons (PAHs) in PM10 of urban, industrial and semi-urban areas in Malaysia  

NASA Astrophysics Data System (ADS)

Particulate matter (PM10) associated with polycyclic aromatic hydrocarbons (PAHs) in ambient air were determined at two sites within the Klang Valley, Kuala Lumpur (urban, KL) and Petaling Jaya (industrial, PJ), and one site outside the Klang Valley, Bangi (semi-urban, BG). This study aimed to determine the concentration and distribution of PAHs in PM10 and the source of origin through principal component analysis (PCA) and diagnostic ratio analysis. This study also assessed the health risk from exposure to airborne BaPeq. PM10 samples were collected on glass fiber filter paper using a High Volume Sampler (HVS) for 24 h between September 2010 and April 2011. The filter papers with PM10 were extracted using dichloromethane-methanol (3:1), and analysis of 16 USEPA priority PAHs was determined using gas chromatography with mass spectra (GC-MS). Health risk assessment was estimated using toxic equivalency factors (TEFs) and incremental lifetime cancer risk (ILCR) which quantitatively estimate the exposure risk for age specific group. The results showed that the total PAHs concentrations throughout seasonal monsoons for KL, PJ and BG ranged from 1.33 ng m-3 to 2.97 ng m-3, 2.24 ng m-3 to 4.84 ng m-3 and 1.64 ng m-3 to 3.45 ng m-3 respectively. More than 80% of total PAHs consisted of 5-ring and 6-ring PAHs such as benzo[a]pyrene (BaP), indeno[1,2,3-cd]pyrene (IcP), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF) and benzo[g,h,i]perylene (BgP). The presence of benzo[g,h,i]perylene (BgP) with high concentration at all locations suggested a source indicator for traffic emission. PCA and diagnostic ratio analysis also suggested substantial contributions from traffic emission with minimal influence from coal combustion and natural gas emissions. The use of total BaPeq concentration provide a better estimation of carcinogenicity activities, where they contributed to more than 50% of the potential health risk. Health risk assessment showed that the estimated incremental lifetime cancer risk (ILCR) from exposure to airborne BaPeq is negligible at all sampling sites for all age specific group.

Jamhari, Anas Ahmad; Sahani, Mazrura; Latif, Mohd Talib; Chan, Kok Meng; Tan, Hock Seng; Khan, Md Firoz; Mohd Tahir, Norhayati

2014-04-01

96

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

97

Accumulation, Allocation, and Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Soil-Brassica chinensis System.  

PubMed

Farmland soil and leafy vegetables accumulate more polycyclic aromatic hydrocarbons (PAHs) in suburban sites. In this study, 13 sampling areas were selected from vegetable fields in the outskirts of Xi'an, the largest city in northwestern China. The similarity of PAH composition in soil and vegetation was investigated through principal components analysis and redundancy analysis (RDA), rather than discrimination of PAH congeners from various sources. The toxic equivalent quantity of PAHs in soil ranged from 7 to 202 ?g/kg d.w., with an average of 41 ?g/kg d.w., which exceeded the agricultural/horticultural soil acceptance criteria for New Zealand. However, the cancer risk level posed by combined direct ingestion, dermal contact, inhalation of soil particles, and inhalation of surface soil vapor met the rigorous international criteria (1×10-6). The concentration of total PAHs was (1052±73) ?g/kg d.w. in vegetation (mean±standard error). The cancer risks posed by ingestion of vegetation ranged from 2×10-5 to 2×10-4 with an average of 1.66×10-4, which was higher than international excess lifetime risk limits for carcinogens (1×10-4). The geochemical indices indicated that the PAHs in soil and vegetables were mainly from vehicle and crude oil combustion. Both the total PAHs in vegetation and bioconcentration factor for total PAHs (the ratio of total PAHs in vegetation to total PAHs in soil) increased with increasing pH as well as decreasing sand in soil. The total variation in distribution of PAHs in vegetation explained by those in soil reached 98% in RDA, which was statistically significant based on Monte Carlo permutation. Common pollution source and notable effects of soil contamination on vegetation would result in highly similar distribution of PAHs in soil and vegetation. PMID:25679782

Zhang, Juan; Fan, Shukai; Du, Xiaoming; Yang, Juncheng; Wang, Wenyan; Hou, Hong

2015-01-01

98

Accumulation, Allocation, and Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Soil-Brassica chinensis System  

PubMed Central

Farmland soil and leafy vegetables accumulate more polycyclic aromatic hydrocarbons (PAHs) in suburban sites. In this study, 13 sampling areas were selected from vegetable fields in the outskirts of Xi’an, the largest city in northwestern China. The similarity of PAH composition in soil and vegetation was investigated through principal components analysis and redundancy analysis (RDA), rather than discrimination of PAH congeners from various sources. The toxic equivalent quantity of PAHs in soil ranged from 7 to 202 ?g/kg d.w., with an average of 41 ?g/kg d.w., which exceeded the agricultural/horticultural soil acceptance criteria for New Zealand. However, the cancer risk level posed by combined direct ingestion, dermal contact, inhalation of soil particles, and inhalation of surface soil vapor met the rigorous international criteria (1×10?6). The concentration of total PAHs was (1052±73) ?g/kg d.w. in vegetation (mean±standard error). The cancer risks posed by ingestion of vegetation ranged from 2×10?5 to 2×10?4 with an average of 1.66×10?4, which was higher than international excess lifetime risk limits for carcinogens (1×10?4). The geochemical indices indicated that the PAHs in soil and vegetables were mainly from vehicle and crude oil combustion. Both the total PAHs in vegetation and bioconcentration factor for total PAHs (the ratio of total PAHs in vegetation to total PAHs in soil) increased with increasing pH as well as decreasing sand in soil. The total variation in distribution of PAHs in vegetation explained by those in soil reached 98% in RDA, which was statistically significant based on Monte Carlo permutation. Common pollution source and notable effects of soil contamination on vegetation would result in highly similar distribution of PAHs in soil and vegetation. PMID:25679782

Zhang, Juan; Fan, Shukai; Du, Xiaoming; Yang, Juncheng; Wang, Wenyan; Hou, Hong

2015-01-01

99

Toxicokinetics of PAHs in Hexagenia  

USGS Publications Warehouse

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

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

1990-01-01

100

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

101

PAHs in the urban air of Sarajevo: levels, sources, day/night variation, and human inhalation risk.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) are organic pollutants derived from pyrolysis and pyrosynthesis processes. Industrial activity, motor vehicle emission, and domestic combustion are the main sources of PAHs in the urban atmosphere. In this work, samples collected during the day and night in the urban area of Sarajevo are analyzed separately for gaseous and particle-bound PAHs; the possible origin of PAHs at the receptor site was suggested using different methods applied to the solid phase and to the total PAHs (gaseous + particulate phase). Finally, the risk level in Sarajevo associated to the carcinogenic character of the studied PAHs has been assessed. The result of this study suggests that (a) the total PAH concentrations were higher than those reported in other European cities; (b) the PAH daytime concentrations are higher than nocturnal concentrations: the sum of the PAH day/night ratios is 1.52 (gas) and 1.45 (particle phase); (c) stationary combustion and traffic were suggested to be the main sources of PAHs; (d) the average particle-bound benzo(a)pyrene (BaP) concentration (5.4 ng/m(3)) is higher than EU target annual value (1 ng/m(3)); and (e) PAH cancer risk exceeds the carcinogenic benchmark level recommended by the EPA mainly due to BaP during both the day and night periods. PMID:24249248

De Pieri, Silvia; Arruti, Axel; Huremovic, Jasna; Sulejmanovic, Jasmina; Selovic, Alisa; Ðor?evi?, Dragana; Fernández-Olmo, Ignacio; Gambaro, Andrea

2014-03-01

102

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

103

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

104

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

105

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

106

Atmospheric size distribution of PAHs: evidence of a high-volume sampling artifact.  

PubMed

The purpose of this study was to characterize atmospheric levels of four- to six-ring polycyclic aromatic hydrocarbons (PAHs) in the vicinity of a horizontal stud Söderberg aluminum smelter in terms of the size distribution of particulate matter (September to December 2002). It was found that the vast majority of the PAHs was associated with particle diameters less than 1 and 3 microm. A profile comparison of the PAH mixture--using benzo[a]pyrene (B[a]P) relative abundance ratios (PAH/B[a]P)--for the cascade impactor filters indicated the formation of a sampling artifact. Overall, the PAH stability scale generated in this study agrees with those produced experimentally for ozone and nitrogen dioxides or developed using other in situ measurement techniques. Correlations of the four- to six-ring PAHs with other atmospheric variables suggested that smelter plume conditions and particle characteristics may play a potentially important role in the overall PAH reactivity. To our knowledge, this is the first study to report a sampling artifact for the four- to six-ring PAHs during in situ high volume sampling under real world conditions. PMID:16245837

Sanderson, Eric G; Farant, J P

2005-10-01

107

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

108

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

109

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

110

Atmospheric reactions influence seasonal PAH and nitro-PAH concentrations in the Los Angeles basin.  

PubMed

Ambient measurements of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs were carried out during August 2002 and January 2003 in Los Angeles, CA, a source site and in Riverside, CA, a downwind receptor site approximately 90 km to the east of Los Angeles. Atmospheric concentrations of PAHs and nitro-PAHs are of interest because both of these compound classes include potent mutagens and carcinogens. To augment our current understanding of atmospheric formation of nitro-PAHs, four sampling periods were employed to study the diurnal variations of these compounds. The PAH concentrations were highest in Los Angeles during January, as a result of traffic input at this source site undertightwintertime atmospheric inversions. In contrast, nitro-PAH levels were highest in Riverside during August, as a result of enhanced summertime photochemistry. Hydroxyl radical-initiated reactions produced nitro-PAHs in both seasons, while in winter little evidence for nitrate radical chemistry was seen. For the August samples, nitrate radical-initiated formation of nitro-PAHs is suggested by nitro-PAH isomer profiles not only at the downwind location as anticipated, but also atthe source site. In southern California, the contribution of atmospheric formation through gas-phase radical-initiated PAH reactions to the ambient burden of nitro-PAHs is dominant, with the semi-volatile nitro-PAHs being the most abundant and 2-nitrofluoranthene being the major particle-associated nitro-PAH. PMID:15667076

Reisen, Fabienne; Arey, Janet

2005-01-01

111

Sources and Significance of Alkane and PAH Hydrocarbons in Canadian Arctic Rivers  

NASA Astrophysics Data System (ADS)

Hydrocarbon measurements have been made on dissolved, suspended particulate and sediment samples collected in 1987, 1993 and 1994 from the Mackenzie River delta and shelf and in 1993 from 10 smaller Northwest Territories and Nunavut rivers that drain into the Canadian Archipelago or Hudson's Bay. Suspended particulate samples from all rivers have a resolved higher alkane pattern with a well-defined odd-even predominance consistent with a major source in terrestrial, vascular plant material. Particulate samples from the 10 smaller rivers have alkane concentrations that are similar to the Mackenzie River during summer, but PAH (polycyclic aromatic hydrocarbon) concentrations are approximately 10 times lower for the parent PAHs and 100 times lower for alkyl PAHs. PAHs on suspended particulate from the Mackenzie River exhibit a uniform composition typical of mature petrogenic sources, while PAHs in the smaller rivers are typical of combustion. The virtual absence of petrogenic PAHs in the smaller rivers is the single most important difference between these and the Mackenzie River. During summer the alkane and PAH composition of suspended particulate in the Mackenzie River is sufficiently homogenous to estimate directly the hydrocarbon load from the particulate load. Mackenzie River particulates and sediments have the hopane and sterane ratios characteristic of immature bitumens, shales or coals from the Devonian Canol formation that outcrops in the lower Mackenzie River valley. The erosion of organic-rich rocks from this formation is likely the source of the refractory petrogenic material found in the Mackenzie River delta and shelf. Data are insufficient to determine whether the petrogenic lower alkanes and PAHs have the same source or whether more mature petroleum also contributes. Because sediment samples (suspended and bed) from the Mackenzie delta have natural PAH concentrations that exceed the level where adverse biological effects are expected to occur, there is an urgent need to establish whether these petroleum-derived PAHs are bioavailable and if they are inducing effects in bottom fish and other biota.

Yunker, M. B.; Backus, S. M.; Graf Pannatier, E.; Jeffries, D. S.; Macdonald, R. W.

2002-07-01

112

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.

113

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

114

Sources, fate, and toxic hazards of oxygenated polycyclic aromatic hydrocarbons (PAHs) at PAH-contaminated sites.  

PubMed

In this paper we show that oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) are important cocontaminants that should be taken into account during risk assessment and remediation of sites with high levels of PAHs. The presented data, which have been collected both from our own research and the published literature, demonstrate that oxy-PAHs are abundant but neglected contaminants at these sites. The oxy-PAHs show relatively high persistency and because they are formed through transformation of PAHs, their concentrations in the environment may even increase as the sites are remediated by methods that promote PAH degradation. Furthermore, we show that oxy-PAHs are toxic to both humans and the environment, although the toxicity seems to be manifested through other effects than those known to be important for polycyclic aromatic compounds in general, that is, mutagenicity and carcinogenicity. Finally, we present data that support the hypothesis that oxy-PAHs are more mobile in the environment than PAHs, due to their polarity, and thus have a higher tendency to spread from contaminated sites via surface water and groundwater. We believe that oxy-PAHs should be included in monitoring programs at PAH-contaminated sites, even if a number of other toxicologically relevant compounds that may also be present, such as nitro-PAHs and azaarenes, are not monitored. This is because oxy-PAH levels are difficult to predict from the PAH levels, because their environmental behavior differs substantially from that of PAHs, and oxy-PAHs may be formed as PAHs are degraded. PMID:17985702

Lundstedt, Staffan; White, Paul A; Lemieux, Christine L; Lynes, Krista D; Lambert, Iain B; Oberg, Lars; Haglund, Peter; Tysklind, Mats

2007-09-01

115

Diurnal cycle of PAHs, nitro-PAHs, and oxy-PAHs in a high oxidation capacity marine background atmosphere.  

PubMed

To improve our understanding of the formation and fate of nitro-PAHs, which contribute to the toxicity of ambient particles, the diurnal variation of their ambient concentration was studied concurrently with the corresponding PAH, OH radical, ozone, and oxy-PAH concentration, during an intensive field campaign at an eastern Mediterranean marine background location (Finokalia, Island of Crete) in August, 2001. The gas-phase PAH and OH radical concentrations maximized at noon. Gas-phase PAH concentrations were correlated (p < 0.001) with ambient temperatures. The gas-phase OH-radical-initiated PAH reaction was identified as the major process contributing to the ambient burden of nitro-PAHs. 2-Nitrofluoranthene and 2-nitropyrene were the most abundant particle-associated nitro-PAHs. A well-defined diurnal pattern was identified for both compounds exhibiting a maximum during midday followed by a rapid decrease. 9,10-Anthracenodione and 9-fluorenone, the most abundant oxy-PAHs, did not present a diurnal variation of concentration. PMID:18186330

Tsapakis, Manolis; Stephanou, Euripides G

2007-12-01

116

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

117

PAHs in some brands of tea.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) are a class of environmental pollutants generated from incomplete combustion of organic materials. PAHs in tea have been studied for five locally available brands. Six to seven PAHs from list of 16 priority pollutants (US EPA) were found to be present in samples of various brands of tea. Benzo[a]pyrene (2A: probable human carcinogen) was found in two samples, and naphthalene (2B: possible human carcinogen) was found in all the tea samples. PMID:20665110

Singh, Satnam; Vashishth, Amit; Vishal

2011-06-01

118

PAH emission from various industrial stacks  

Microsoft Academic Search

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

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

1998-01-01

119

[Distribution characteristics and sources identification of PAHs in ancient paddy soil].  

PubMed

Soil samples of current paddy soils, ancient paddy soil/ancient dry land soil, and bottom soils were collected from two sites in Chuodunshan Site of Majiabang Culture (about 6,000a). 15 polycyclic aromatic hydrocarbons (PAHs) were analyzed with HPLC, and their possible sources were identified. The sum of 15 PAHs was 202.9microg x kg(-1) and 207.7microg x kg(-1) in the surface soils from Site A and Site B respectively, which were mainly deposited from atmosphere. In ancient paddy soil from Site A, the total PAHs concentration sharply decreased to 56.0microg x kg(-1), but was still higher than those in ancient dry land soil and bottom soils with the sum of 32.0 approximately 36.9microg x kg(-1). In ancient paddy soil, the concentrations of 2-ring and 3-ring PAHs took a larger portion of 63 percents to the total PAHs, and naphthalene and phenanthrene were the most abundant compounds, while PAHs of more than 4 rings took a small part. The ratios of phenanthrene anthracene and benzo(a) anthracene chrysene and 13C-NMR spectrum of soil organic matter showed that PAHs in ancient paddy soil mainly originated from rice straw burning, biogenesis under reducing conditions may be another source. PMID:16921968

Li, Jiu-hai; Dong, Yuan-hua; Cao, Zhi-hong; Wang, Hui; An, Qiong; Hu, Zheng-yi; Yang, Lin-zhang; Lin, Xian-gui; Yin, Rui

2006-06-01

120

Impact of Natural Gas Extraction on PAH Levels in Ambient Air.  

PubMed

Natural gas extraction, often referred to as "fracking," has increased rapidly in the U.S. in recent years. To address potential health impacts, passive air samplers were deployed in a rural community heavily affected by the natural gas boom. Samplers were analyzed for 62 polycyclic aromatic hydrocarbons (PAHs). Results were grouped based on distance from each sampler to the nearest active well. PAH levels were highest when samplers were closest to active wells. Additionally, PAH levels closest to natural gas activity were an order of magnitude higher than levels previously reported in rural areas. Sourcing ratios indicate that PAHs were predominantly petrogenic, suggesting that elevated PAH levels were influenced by direct releases from the earth. Quantitative human health risk assessment estimated the excess lifetime cancer risks associated with exposure to the measured PAHs. Closest to active wells, the risk estimated for maximum residential exposure was 2.9 in 10?000, which is above the U.S. EPA's acceptable risk level. Overall, risk estimates decreased 30% when comparing results from samplers closest to active wells to those farthest. This work suggests that natural gas extraction may be contributing significantly to PAHs in air, at levels that are relevant to human health. PMID:25810398

Paulik, L Blair; Donald, Carey E; Smith, Brian W; Tidwell, Lane G; Hobbie, Kevin A; Kincl, Laurel; Haynes, Erin N; Anderson, Kim A

2015-04-21

121

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

PubMed

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

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

2008-08-15

122

PAHs concentration and toxicity in organic solvent extracts of atmospheric particulate matter and sea sediments.  

PubMed

The concentration of polycyclic aromatic hydrocarbons (PAHs) and the toxicity to marine bacteria (Vibrio fischeri) were measured for the organic solvent extracts of sea sediments collected from an urban watershed area (Hiroshima Bay) of Japan and compared with the concentrations and toxicity of atmospheric particulate matter (PM). In atmospheric PM, the PAHs concentration was highest in fine particulate matter (FPM) collected during cold seasons. The concentrations of sea sediments were 0.01-0.001 times those of atmospheric PM. 1/EC50 was 1-10 L g(-1) PM for atmospheric PM and 0.1-1 L g(-1) dry solids for sea sediments. These results imply that toxic substances from atmospheric PM are diluted several tens or hundreds of times in sea sediments. The ratio of the 1/EC50 to PAHs concentration ((1/EC50)/16PAHs) was stable for all sea sediments (0.1-1 L ?g(-1) 16PAHs) and was the same order of magnitude as that of FPM and coarse particulate matter (CPM). The ratio of sediments collected from the west was more similar to that of CPM while that from the east was more similar to FPM, possibly because of hydraulic differences among water bodies. The PAHs concentration pattern analyses (principal component analysis and isomer ratio analysis) were conducted and the results showed that the PAHs pattern in sea sediments was quite different to that of FPM and CPM. Comparison with previously conducted PAHs analyses suggested that biomass burning residues comprised a major portion of these other sources. PMID:22797225

Ozaki, Noriatsu; Takeuchi, Shin-ya; Kojima, Keisuke; Kindaichi, Tomonori; Komatsu, Toshiko; Fukushima, Takehiko

2012-01-01

123

Polycyclic Aromatic Hydrocarbons (PAHs) in Indoor Dusts of Guizhou, Southwest of China: Status, Sources and Potential Human Health Risk  

PubMed Central

Polycyclic aromatic hydrocarbons (PAHs) were analyzed for 136 indoor dust samples collected from Guizhou province, southwest of China. The ?18PAHs concentrations ranged from 2.18 ?g•g-1 to 14.20 ?g•g-1 with the mean value of 6.78 ?g•g-1. The highest ?18PAHs concentration was found in dust samples from orefields, followed by city, town and village. Moreover, the mean concentration of ?18PAHs in indoor dust was at least 10% higher than that of outdoors. The 4–6 rings PAHs, contributing more than 70% of ?18PAHs, were the dominant species. PAHs ratios, principal component analysis with multiple linear regression (PCA-MLR) and hierarchical clustering analysis (HCA) were applied to evaluate the possible sources. Two major origins of PAHs in indoor dust were identified as vehicle emissions and coal combustion. The mean incremental lifetime cancer risk (ILCR) due to human exposure to indoor dust PAHs in city, town, village and orefield of Guizhou province, China was 6.14×10?6, 5.00×10?6, 3.08×10?6, 6.02×10?6 for children and 5.92×10?6, 4.83×10?6, 2.97×10?6, 5.81×10?6 for adults, respectively. PMID:25719362

Li, Baizhan

2015-01-01

124

Bacterial biodegradation of polycyclic aromatic hydrocarbons (PAH) and potential effects of surfactants on PAH bioavailability  

SciTech Connect

The purposes of this project were to evaluate whether indigenous microorganisms from polycyclic aromatic hydrocarbons (PAH)-contaminated soils produce surfactants (biosurfactants) as a means of enhancing the bioavailability of PAH; to improve the understanding of the general physiology of a diverse group of PAH-degrading bacteria; and to study in general how surfactants influence the biodegradation of hydrophobic chemicals.

Aitken, M.D.; Grimberg, S.J.; Nagel, J.; Nagel, R.D.; Stringfellow, W.T.

1996-02-01

125

SAMPLING AND ANALYSIS OF POLYCYCLIC AROMATIC HYDROCARBONS (PAH) AND OXYGENATED PAH IN  

E-print Network

SAMPLING AND ANALYSIS OF POLYCYCLIC AROMATIC HYDROCARBONS (PAH) AND OXYGENATED PAH IN DIESEL Hydrocarbons (PAH) and their oxygenated derivatives occur in particles or in the vapour phase in the atmosphere that is the result of the incomplete combustion of diesel fuel and lubricants. In general 10 % to 40

Paris-Sud XI, Université de

126

Sorptive behavior of nitro-PAHs in street runoff and their potential as indicators of diesel vehicle exhaust particles.  

PubMed

This is the first report to reveal the particle-water distribution of nitropolycyclic aromatic hydrocarbons (NPAHs) and to discuss their potential risks and utility as indicators of diesel vehicle exhaust particles (DEP). Time-series samples of runoff were collected from a highway, and NPAHs and polycyclic aromatic hydrocarbons (PAHs) were determined by gas chromatography-mass spectrometry (GC-MS) to study their dynamic behavior. The concentrations of total NPAHs ranged from 11 to 73 ng/L in particulate phase (>0.7 mcirom) and from 2.3 to 4.9 ng/L in dissolved phase (<0.7 microm). Like their PAH analogs, most (81-97%) NPAHs were associated with particulate matter. The organic carbon-normalized in situ partition coefficients (Koc') of NPAHs observed in runoff events (10(5.8-6.3) for 2-nitrofluoranthene and 10(5.8-6.2) for 1-nitropyrene [1-NP]) were more than 1 order of magnitude higher than those expected from their Kow, indicating great affinity for particulate matter such as soot. Concentrations of PAHs and NPAHs adjusted by potency equivalency factors and induction equivalency factors showed that the potential risks of NPAHs were smaller than those of PAHs by a factor of more than a hundred for the particulate phase and morethan fourforthe dissolved phase. Comparison of concentrations and compositions of NPAHs and PAHs among runoff, DEP, gasoline vehicle exhaust particles, boiler exhaust particles, and aerosols suggested that the ratio of 1-NP to total PAHs (1-NP/PAH) is a useful indicator of DEP for source apportionment of PAHs among traffic-related sources. Source-apportionment of PAHs in the runoff by 1-NP/PAH and methylphenanthrene/phenanthrene ratios suggested that most PAHs in the runoff except the second flush peak were derived from DEP but that other pyrogenic sources contributed to the particles at the second flush and thus to the overall runoff particles. PMID:18351085

Murakami, Michio; Yamada, Junya; Kumata, Hidetoshi; Takada, Hideshige

2008-02-15

127

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

128

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

129

Presence of polycyclic aromatic hydrocarbons (PAHs) in apple in rural terrains from Mexico City.  

PubMed

This paper describes PAH concentrations in apple crops that are growing in rural terrains in Mexico City. The concentrations of individual PAHs showed great variability, there being low and high molecular weight compounds in dry (high molecular weight for Tlahuac 7.06 microg/g and Milpa Alta 3.96 microg/g) and wet months (high molecular weight for Tlahuac 11.25 microg/g and Milpa Alta 12.05 microg/g). Some PAHs indicators and cross plot ratios Ant/(Ant + Phe) and Flu/(Flu + Pyr) define fossil fuels and vegetation combustion as the source of contamination over the cuticle of the apples. It is likely that deposition (dry and wet) is the principal source o f contamination over the apple surface. This study reveals the presence of PAHs in apples due to the high air contamination of Mexico City. PMID:20602085

Salinas, Rutilio Ortiz; González, Gilberto Díaz; Bermudez, Beatriz Schettino; Tolentino, Rey Gutiérrez; Vega Y León, Salvador

2010-08-01

130

Airborne and laboratory studies of interstellar PAHs  

NASA Technical Reports Server (NTRS)

A brief history of the observations which have led to the hypothesis that polycyclic aromatic hydrocarbons (PAH's) are the carriers of the widespread interstellar emission features near 3050, 1615, '1300' and 890 cm(exp -1) (3.29, 6.2, '7.7', and 11.2 mu m) is presented. The central role of airborne spectroscopy is stressed. The principal reason for the assignment to PAH's was the resemblance of the interstellar emission spectrum to the laboratory absorption spectra of PAH's and PAH-like materials. Since precious little information was available on the properties of PAH's in the forms that are thought to exist under interstellar conditions -isolated and ionized in the emission zones, with the smallest PAH's being dehydrogenated- there was a need for a spectral data base on PAH's taken in these states. Here, the relevant infrared spectroscopic properties of PAH's will be reviewed. These laboratory spectra show that relative band intensities are severely altered and that band frequencies shift. It is shown that these new data alleviate several of the spectroscopic criticisms previously leveled at the hypothesis.

Allamandola, L. J.; Sandford, S. A.; Hudgins, D. M.; Witteborn, Fred C.

1995-01-01

131

The thermodynamic landscape of methanogenic PAH degradation  

PubMed Central

Summary Methanogenic degradation of polycyclic aromatic hydrocarbons (PAHs) has long been considered impossible, but evidence in contaminated near surface environments and biodegrading petroleum reservoirs suggests that this is not necessarily the case. To evaluate the thermodynamic constraints on methanogenic PAH degradation we have estimated the Gibbs free energy values for naphthalene, phenanthrene, anthracene, pyrene and chrysene in the aqueous phase, and used these values to evaluate several possible routes whereby PAHs may be converted to methane. Under standard conditions (25°C, solutes at 1?M concentrations, and gases at 1?atm), methanogenic degradation of these PAHs yields between 209 and 331?kJ?mol?1. Per mole of methane produced this is 27–35?kJ?mol?1, indicating that PAH?based methanogenesis is exergonic. We evaluated the energetics of three potential PAH degradation routes: oxidation to H2/CO2, complete conversion to acetate, or incomplete oxidation to H2 plus acetate. Depending on the in situ conditions the energetically most favourable pathway for the PAH?degrading organisms is oxidation to H2/CO2 or conversion into acetate. These are not necessarily the pathways that prevail in the environment. This may be because the kinetic theory of optimal length of metabolic pathways suggests that PAH degraders may have evolved towards incomplete oxidation to acetate plus H2 as the optimal pathway. PMID:21255289

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

2009-01-01

132

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...

133

Infrared fluorescence from PAHs in the laboratory  

NASA Technical Reports Server (NTRS)

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

Cherchneff, Isabelle; Barker, John R.

1989-01-01

134

Diagnostic accuracy of the magnetic resonance Parkinsonism index and the midbrain-to-pontine area ratio to differentiate progressive supranuclear palsy from Parkinson's disease and the Parkinson variant of multiple system atrophy.  

PubMed

Using magnetic resonance (MR) planimetry, both the midbrain-to-pontine area ratio (m/p-ratio) and the MR parkinsonism index (MRPI) have been shown to assist in the differential diagnosis of progressive supranuclear palsy (PSP) from Parkinson's disease (PD) and the Parkinson variant of multiple system atrophy (MSA-P). The aim of this study was to determine the diagnostic accuracy of the MRPI compared with the m/p-ratio in a large cohort of 123 patients with neurodegenerative parkinsonism including patients with PSP, PD, and MSA-P. Patients with PSP had significant higher MRPI values and significant smaller m/p-ratios compared with the other groups with overlapping individual values. Overall predictive accuracy was similar for the m/p-ratio (87.0%) and the MRPI (80.5%) with a predictive accuracy for PSP from MSA-P being significantly better for the MRPI (87.5%) compared with the m/p-ratio (75%) as well as a predictive accuracy for PSP from PD being significantly better for the m/p-ratio (87.6%) compared with the MRPI (77.3%). Both the m/p-ratio and the MRPI may assist the clinical differential diagnosis in neurodegenerative parkinsonism. PMID:20878992

Hussl, Anna; Mahlknecht, Philipp; Scherfler, Christoph; Esterhammer, Regina; Schocke, Michael; Poewe, Werner; Seppi, Klaus

2010-10-30

135

Are PAH molecules the carriers of Unidentified Infrared Emission bands?  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbon (PAH) molecules are widely considered as the preferred candidate for the carrier of the unidentified infrared emission bands observed in the interstellar medium and circumstellar envelopes. In this paper we report the result of fitting a variety of non-PAH spectra (silicates, hydrogenated amorphous carbon, coal and even artificial spectra) using the theoretical infrared spectra of PAHs from the NASA Ames PAH IR Spectroscopic Database. We show that these non-PAH spectra can be well fitted by PAH mixtures. This suggest that a general match between astronomical spectra and those of PAH mixtures does not necessarily provide definitive support for the PAH hypothesis.

Kwok, Sun; Zhang, Yong

2015-01-01

136

PAHs and nitrated PAHs in air of five European countries determined using SPMDs as passive samplers  

NASA Astrophysics Data System (ADS)

The gas phase polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs in the atmosphere of five European countries (Austria, the Czech Republic, Poland, Slovakia and Sweden) were measured simultaneously during two 21-day passive sampling campaigns using semipermeable membrane devices (SPMDs). SPMD samplers, consisting of a pair of SPMDs covered by a metal umbrella, were deployed at 40 locations ranging from remote and rural to urban and industrial, at a similar time during each of the two sampling campaigns (autumn 1999, except in Poland, winter 1999, and summer 2000). The total amounts of PAHs and nitro-PAHs found in the SPMDs ranged between 5.0-1.2×10 3 and 1.1×10 -3-4.0 ng SPMD -1 day -1, respectively. The measured environmental sampling conditions were similar between sites and, thus, the variations in the SPMD data reflected the spatial differences in gas phase concentrations of nitro-PAHs and PAHs within and between countries. The gas phase concentrations of nitro-PAHs and PAHs found in East Europe (Slovakia, the Czech Republic and Poland 1999) were 10 times higher than those measured in Sweden, Austria and Poland in 2000. In each country, the levels of PAHs and nitro-PAHs differed by one-three orders of magnitudes amongst sampling sites. The highest within-country spatial differences were found in Poland where levels of PAHs and nitro-PAHs were about one and two orders of magnitudes, respectively, higher in winter 1999 than in summer 2000, probably due to increasing emissions of coal combustion for residential heating. Differences in PAH-patterns between sites were visualized by the multivariate projection method, principal component analysis (PCA). However, no specific source patterns were found, probably since imissions rather than emissions were measured, so the PAHs detected at many sites originated from multiple sources.

Söderström, Hanna; Hajšlová, Jana; Kocourek, Vladimir; Siegmund, Barbara; Kocan, Anton; Obiedzinski, Mieczys?aw W.; Tysklind, Mats; Bergqvist, Per-Anders

137

Theoretical evaluation of PAH dications properties  

E-print Network

Aims. We present a systematic theoretical study on 40 polycyclic aromatic hydrocarbons dications (PAHs++) containing up to 66 carbon atoms. Methods. We performed our calculations using well established quantum-chemical techniques in the framework of the density functional theory (DFT) to obtain the electronic ground-state properties, and of the time-dependent DFT (TD-DFT) to evaluate the excited\\textendash state properties. Results. For each PAH++ considered we computed the absolute visible-UV photo-absorption cross-section up to about 30 eV. We also evaluated their vibrational properties and compared them to those of the corresponding neutral and singly-ionised species. We estimated the adiabatic and vertical second ionisation energy DeltaI through total energy differences. Conclusions. The DeltaI values obtained fall in the energy range 8-13 eV, confirming that PAHs could reach the doubly-ionised state in HI regions. The total integrated IR absorption cross-sections show a marked increase upon ionization, being on the average about two and five times larger for PAHs++ than for PAHs+ and PAHs, respectively. The visible-UV photo-absorption cross-sections for the 0, +1 and +2 charge-states show comparable features but PAHs++ are found to absorb slightly less than their parent neutrals and singly ionized species between ~7 and ~12 eV. Combining these pieces of information we found that PAHs++ should actually be more stable against photodissociation than PAHs and PAHs+,_if_ dissociation tresholds are nearly unchanged by ionization.

G. Malloci; C. Joblin; G. Mulas

2006-09-25

138

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

PubMed

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

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

2014-07-01

139

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

140

Spitzer Spectroscopy of Infrared-luminous Galaxies: Diagnostics of Active Galactic Nuclei and Star Formation and Contribution to Total Infrared Luminosity  

NASA Astrophysics Data System (ADS)

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 ?m) > 1.2 mJy. The MIR spectra cover wavelengths 5-38 ?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 IR = L(8-1000 ?m) = 1010-1012 L ? (median L IR of 3.0 × 1011 L ?). We divide our sample into a subsample of galaxies with Spitzer Infrared Array Camera 3.6-8.0 ?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] ?12.8 ?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 11.3/L 7.7 and L 6.2/L 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] ?25.9 ?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; Rieke, George H.; Dey, Arjun; Jannuzi, Buell T.; Moustakas, John; Weiner, Benjamin

2013-05-01

141

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

PubMed Central

Atmospheric particulate matter with diameter <2.5 um (PM2.5) was collected at Peking University (PKU) in Beijing, China before, during, and after the 2008 Olympics and analyzed for black carbon (BC), organic carbon (OC), lower molecular weight (MW<300) and MW302 Polycyclic Aromatic Hydrocarbons (PAHs), nitrated PAHs (NPAHs) and oxygenated PAHs (OPAHs). In addition, the direct and indirect acting mutagenicity of the PM2.5 and the potential for DNA damage to human lung cells were also measured. Significant reductions in BC (45%), OC (31%), MW< 300 PAH (26% – 73%), MW 302 PAH (22% – 77%), NPAH (15% – 68%) and OPAH (25% – 53%) concentrations were measured during the source control and Olympic Olympic period. However, the mutagenicity of the PM2.5 was significantly reduced only during the Olympic period. The PAH, NPAH, and OPAH composition of the PM2.5 was similar throughout the study, suggesting similar sources during the different periods. During the source control period, the parent PAH concentrations were correlated with NO, CO, and SO2 concentrations, indicating that these PAHs were associated with both local and regional emissions. However, the NPAH and OPAH concentrations were only correlated with the NO concentrations, indicating that the NPAH and OPAH were primarily associated with local emissions. The relatively high 2-nitrofluoranthene/1-nitropyrene ratio (25 – 46) and 2-nitrofluoranthene/2-nitropyrene ratio (3.4 – 4.8), suggested a predominance of photochemical formation of NPAHs through OH-radical-initiated reactions in the atmosphere. On average, the ?NPAH and ?OPAH concentrations were 8% of the parent PAH concentrations, while the direct-acting mutagenicity (due to the NPAH and OPAH) was 200% higher than the indirect-acting mutagenicity (due to the PAH). This suggests that NPAH and OPAH make up a significant portion of the overall mutagenicity of PM2.5 in Beijing. PMID:21766847

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

2011-01-01

142

Concentration and photochemistry of PAHs, NPAHs, and OPAHs and toxicity of PM2.5 during the Beijing Olympic Games.  

PubMed

Atmospheric particulate matter with diameter <2.5 um (PM(2.5)) was collected at Peking University (PKU) in Beijing, China before, during, and after the 2008 Olympics and analyzed for black carbon (BC), organic carbon (OC), lower molecular weight (MW < 300) and MW302 Polycyclic Aromatic Hydrocarbons (PAHs), nitrated PAHs (NPAHs) and oxygenated PAHs (OPAHs). In addition, the direct and indirect acting mutagenicity of the PM(2.5) and the potential for DNA damage to human lung cells were also measured. Significant reductions in BC (45%), OC (31%), MW< 300 PAH (26-73%), MW 302 PAH (22-77%), NPAH (15-68%), and OPAH (25-53%) concentrations were measured during the source control and Olympic periods. However, the mutagenicity of the PM(2.5) was significantly reduced only during the Olympic period. The PAH, NPAH, and OPAH composition of the PM(2.5) was similar throughout the study, suggesting similar sources during the different periods. During the source control period, the parent PAH concentrations were correlated with NO, CO, and SO(2) concentrations, indicating that these PAHs were associated with both local and regional emissions. However, the NPAH and OPAH concentrations were only correlated with the NO concentrations, indicating that the NPAH and OPAH were primarily associated with local emissions. The relatively high 2-nitrofluoranthene/1-nitropyrene ratio (25-46) and 2-nitrofluoranthene/2-nitropyrene ratio (3.4-4.8), suggested a predominance of photochemical formation of NPAHs through OH-radical-initiated reactions in the atmosphere. On average, the ?NPAH and ?OPAH concentrations were 8% of the parent PAH concentrations, while the direct-acting mutagenicity (due to the NPAH and OPAH) was 200% higher than the indirect-acting mutagenicity (due to the PAH). This suggests that NPAH and OPAH make up a significant portion of the overall mutagenicity of PM(2.5) in Beijing. PMID:21766847

Wang, Wentao; Jariyasopit, Narumol; Schrlau, Jill; Jia, Yuling; Tao, Shu; Yu, Tian-Wei; Dashwood, Roderick H; Zhang, Wei; Wang, Xuejun; Simonich, Staci L Massey

2011-08-15

143

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

PubMed

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

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

2007-07-01

144

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

145

Histopathological Diagnostic Value of the IgG4+/IgG+ Ratio of Plasmacytic Infiltration for IgG4-Related Diseases: A PRISMA-Compliant Systematic Review and Meta-Analysis.  

PubMed

This article aims to perform a meta-analysis to evaluate the diagnostic value of the immunoglobulin G (IgG)4/IgG ratio of plasmacytic infiltration for IgG4-related diseases.Four databases-EMBASE, ISI Web of Knowledge, PubMed, and the Cochrane Library-were systematically searched. Approximately 200 participants from several studies were included in this research. STATA 11.2 software (Stata Corporation, College Station, TX) and Meta-DiSc 1.4 (Unit of Clinical Biostatistics, Ramon y Cajal Hospital, Madrid, Spain) were used to perform the meta-analysis.Nine studies were included in the meta-analysis. The pooled diagnostic odds ratio was 18.94 [95% confidence interval (CI), 2.89-124.30]. The sensitivity was 58.80% (95% CI, 50.90-66.30) and the specificity was 90.20% (95% CI, 81.20-95.80). The positive and negative likelihood ratios were 3.12 (95% CI, 1.07-9.16) and 0.26 (95% CI, 0.09-0.70), respectively. The area under the curve of the summary receiver-operating characteristic was 0.88.To conclude, the IgG4/IgG ratio of plasmacytic infiltration is modestly effective in diagnosing IgG-related disease. PMID:25738476

Deng, Chuiwen; Li, Wenli; Chen, Si; Zhang, Wen; Li, Jing; Hu, Chaojun; Wen, Xiaoting; Zhang, Fengchun; Li, Yongzhe

2015-03-01

146

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

147

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

148

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

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs, and oxy-PAHs were studied in the atmospheric particulate matter of a subtropical rural region (São Paulo State, Brazil) affected by emissions from sugar cane burning. Diurnal and nocturnal samples were collected from May to June of 2010. In general, average PAH concentrations were significantly higher at night, suggesting that the compounds were predominantly emitted to the atmosphere during biomass burning (which was mainly performed at night). The maximum average PAH concentration was found for benzo[b]fluoranthene at night (2.9 ± 5.4 ng m-3). Among the nitro-PAH compounds, the highest average concentrations were obtained for 9-nitrophenanthrene in diurnal and nocturnal samples (1.5 ± 1.2 and 1.3 ± 2.1 ng m-3, respectively). In contrast to the PAH and nitro-PAH compounds, the oxy-PAHs could not be directly associated with sugar cane burning. The most abundant oxy-PAH compound was benzanthrone (1.6 ± 1.3 ng m-3) at night, followed by 9,10-anthraquinone (1.1 ± 0.9 ng m-3) and 9-fluorenone (0.4 ± 0.1 ng m-3) during the day. A correlation matrix was used to explore the origins of the different compounds. The data suggested that during the daytime, direct emissions (mainly in vehicle exhaust) contributed to the presence of PAHs, nitro-PAHs, and oxy-PAHs in air. Photochemical production also appeared to be a source of the majority of nitro-PAHs and oxy-PAHs, while photolysis could have contributed to removal of the nitro-PAHs during the daytime. At night, sugar cane burning emissions were the primary source of the PAHs and nitro-PAHs, with additional sources also contributing to the levels of oxy-PAHs in the atmosphere.

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

2014-02-01

149

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

PubMed

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

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

2013-04-15

150

Polycyclic aromatic hydrocarbons (PAHs) in sea sediments of the Turkish Mediterranean coast, composition and sources.  

PubMed

The concentrations of polycyclic aromatic hydrocarbons (PAHs) were determined in 25 surface sediment samples from five sites located at Oludeniz Lagoon of the Turkish Mediterranean coast. The total concentration of the PAHs (1.85?±?1.39 mg/kg) was lower than the sediments from highly urbanized areas, while it was comparable with the sediments from similar locations. Acenaphthene and chrysene were dominant ones with the concentrations of 0.620 and 0.515 mg/kg, respectively. The isomeric ratios indicated that combustion is the predominant source of PAHs in the sediments. Factor analysis solution supports the same finding with three major factors accounting for 71.7 % of the variability in the data. Factor 1 with 43.4 % of the total variance identified as a pyrogenic source (coal combustion; 4 rings PAH and traffic related pollution; 5-6 rings PAHs). Factor 2 (explains 39 % of the total variance) represents PAHs originating from traffic, and factor 3 (explains 12 % of the total variance) represents petrogenic source. Our results suggest that combustion of fossil fuels affects most of the points, followed by combustion of biomass and human activity. PMID:25280504

Tuncel, Semra G; Topal, Tansel

2015-03-01

151

Characterization of alkanes, hopanes, and polycyclic aromatic hydrocarbons (PAHs) in tar-balls collected from the East Coast of Peninsular Malaysia.  

PubMed

The East Coast of Peninsular Malaysia faces the South China Sea and is vulnerable to oil pollution because of intense petroleum production activities in the area. The South China Sea is also a favored route for supertankers carrying crude oil to the Far East. Consequently, oil spills can occur, causing pollution and contamination in the surrounding areas. Residual oil spills stranded on coastal beaches usually end up as tar-balls. Elucidating the sources of tar-balls using a molecular marker approach is essential in assessing environmental impacts and perhaps settling legal liabilities for affected parties. This study utilizes a multimodal molecular marker approach through the use of diagnostic ratios of alkanes, hopanes, and polycyclic aromatic hydrocarbons (PAHs) to determine the source, distribution and weathering of tar-balls. Hopane ratios (e.g., C29/C30, and summation C31-C35/C30 ratios) were used to identify the sources of tar-balls. The weathering effects were distinguished by using alkanes, namely the unresolved complex mixture (UCM) and low molecular weight/high molecular weight (L/H) ratios. Similarly, PAHs were also used for the determination of weathering processes undergone by the tar-balls. This multimodal molecular marker gave a very strong indication of the sources of tar-balls in this study. For example, 16 out of 17 samples originated from South East Asian Crude Oil (SEACO) with one sample from Merang, Terengganu originating from North Sea Oil (Troll). The TRME-2 sample may have come from a supertanker's ballast water discharge. The second possibility is that the tar-ball may have been transported via oceanographic currents. All 'weathered' sample characterizations were based on the presence of UCM and other ratios. The multimodal molecular marker approach applied in this study has enabled us to partially understand the transport behavior of tar-balls in the marine environment and has revealed insights into the weathering process of tar-balls. PMID:18328505

Chandru, Kuhan; Zakaria, Mohamad Pauzi; Anita, Sofia; Shahbazi, Azadeh; Sakari, Mahyar; Bahry, Pourya Shahpoury; Mohamed, Che Abd Rahim

2008-05-01

152

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

153

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

NASA Astrophysics Data System (ADS)

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

Herklotz, Ilka; Gocht, Tilman; Grathwohl, Peter

2010-05-01

154

Dust Masses, PAH Abundances, and Starlight Intensities in the SINGS Galaxy Sample  

E-print Network

Physical dust models are presented for 65 galaxies in the SINGS survey that are strongly detected in the four IRAC bands and three MIPS bands. For each galaxy we estimate (1) the total dust mass, (2) the fraction of the dust mass contributed by PAHs, and (3) the intensity of the starlight heating the dust grains. We find that spiral galaxies have dust properties resembling the dust in the local region of the Milky Way, with similar dust-to-gas ratio, and similar PAH abundance. The observed SEDs, including galaxies with SCUBA photometry, can be reproduced by dust models that do not require "cold" (Tdust. The dust-to-gas ratio is observed to be dependent on metallicity. In the interstellar media of galaxies with A_O=12+log(O/H)>8.1, grains contain a substantial fraction of interstellar Mg, Si and Fe. Galaxies with A_Odust-to-gas ratios that are low for their measured oxygen abundance, but in the regions where infrared emission is detected, the dust-to-gas ratio generally appears to be consistent with a substantial fraction of interstellar Mg, Si, and Fe being contained in dust. The PAH index q_PAH -- the fraction of the dust mass in the form of PAHs -- correlates with metallicity. The nine galaxies in our sample with A_O8.1 have a median q_PAH=3.55%. The derived dust masses favor a value X_CO approx 4e20 cm^{-2}(K kms)^{-1} for the CO to H_2 conversion factor. Except for some starbursting systems (Mrk33, Tolo89, NGC3049), dust in the diffuse ISM dominates the IR power.

B. T. Draine; D. A. Dale; G. Bendo; K. D. Gordon; J. D. T. Smith; L. Armus; C. W. Engelbracht; G. Helou; R. C. Kennicutt; A. Li; H. Roussel; F. Walter; D. Calzetti; J. Moustakas; E. J. Murphy; G. H. Rieke; C. Bot; D. J. Hollenbach; K. Sheth; H. I. Teplitz

2007-03-09

155

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

156

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 (...

157

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

158

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

159

Simplifying Likelihood Ratios  

PubMed Central

Likelihood ratios are one of the best measures of diagnostic accuracy, although they are seldom used, because interpreting them requires a calculator to convert back and forth between “probability” and “odds” of disease. This article describes a simpler method of interpreting likelihood ratios, one that avoids calculators, nomograms, and conversions to “odds” of disease. Several examples illustrate how the clinician can use this method to refine diagnostic decisions at the bedside.

McGee, Steven

2002-01-01

160

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

PubMed

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

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

2014-08-01

161

An Investigation into PAH Destruction in Nearby Supernova Remnants, North Polar Spur and Cygnus Loop  

NASA Astrophysics Data System (ADS)

Our goal in conducting this research was to look at the polycyclic aromatic hydrocarbon (PAH)/large dust grain emission intensity ratio in nearby supernova remnants to find evidence for selective PAH destruction by hot gas and high velocity shock waves within these regions, as predicted by the models of Arendt et al. (2010) and Micelotta et al. (2010a,b). Two supernova remnants were studied- the North Polar Spur (NPS) and the Cygnus Loop. The data for PAHs were obtained from the WISE W3 12 micron all-sky map processed by Meisner & Finkbeiner (2014), and the data for the larger grains come from the IRAS 100 micron all-sky map processed by Schlegel, Finkbeiner & Davis (1998). After obtaining a control PAH/large grain intensity ratio of ~2.8 (DN/px)/(MJy/sr) from two high latitude clouds, MBM 30 and MBM 32, we found that the intensity ratios across the NPS and Cygnus Loop were not far off- ~2.7 (DN/px)/(MJy/sr) and ~3.1 (DN/px)/(MJy/sr), respectively- showing no evidence of selective large-scale PAH destruction in supernova remnants. The individual intensities for both PAHs and large grains do decrease inside the Cygnus Loop, however, suggesting a decrease in abundances of both grain types, which could mean total dust grain destruction with the normal ratios coming from foreground and background dust located in the line of sight of the remnant. In addition, temperature and E(B-V) measurements taken from calibrated IRAS images show that while the dust column density increases in the Eastern Veil of the Cygnus Loop, the dust temperature reaches a local maximum, indicating the heating of large grains by interaction with the hot gas in the remnant. The PAH/large grain ratio in the Eastern Veil does decrease and could be indicative of currently ongoing active grain destruction there, with the PAHs being destroyed on a more rapid timescale than the large grains.We are grateful for financial support from the NSF REU Program grant to the Department of Physics & Astronomy at the University of Toledo.

Burkhart, Sarah M.; Witt, Adolf N.

2015-01-01

162

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

SciTech Connect

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

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

2012-10-15

163

Concentrations and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) and nitrated PAHs (NPAHs) in the atmosphere of North China, and the transformation from PAHs to NPAHs.  

PubMed

The occurrence of polycyclic aromatic hydrocarbons (PAHs) and nitrated derivatives (NPAHs), as well as their transformation may have significant health impacts on humans. To investigate the level, spatial distribution and the transformation process of PAHs and NPAHs in North China, we performed a griddedfield passive air sampling campaign in summer of 2011. The median concentration of 25 PAH congeners and 13 NPAHs was 294 ng m(-3) (or 26.7 mg sample(-1)) and 203 ng sample(-1), respectively. Relative higher level of PAHs in Shanxi Province and NPAHs in megacities was observed. In North China, coal/biomass combustion and photochemical formation was the predominant source of PAHs and NPAHs, respectively.To investigate the relationship between these pollutants, a model incorporating NPAHs, PAHs and NO(2) was established, and the result indicated that NO(2) will promote the transformation processes from PAHs to NPAHs, which may increase the total toxicity of PAH-NPAH mixtures. PMID:25463710

Lin, Yan; Qiu, Xinghua; Ma, Yiqiu; Ma, Jin; Zheng, Mei; Shao, Min

2015-01-01

164

PAHs and nitrated PAHs in air of five European countries determined using SPMDs as passive samplers  

Microsoft Academic Search

The gas phase polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs in the atmosphere of five European countries (Austria, the Czech Republic, Poland, Slovakia and Sweden) were measured simultaneously during two 21-day passive sampling campaigns using semipermeable membrane devices (SPMDs). SPMD samplers, consisting of a pair of SPMDs covered by a metal umbrella, were deployed at 40 locations ranging from remote and

Hanna Söderström; Jana Hajšlová; Vladimir Kocourek; Barbara Siegmund; Anton Kocan; Mieczys?aw W. Obiedzinski; Mats Tysklind; Per-Anders Bergqvist

2005-01-01

165

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

166

Nitro-PAH compounds in the atmosphere of Sao Paulo, Brazil  

NASA Astrophysics Data System (ADS)

Nitrated polycyclic aromatic hydrocarbons (nitro-PAH) are the chemical class with potent mutagenic compounds. These species are emitted from a wide range of combustion sources. Some compounds can be formed photo chemically via reactions of their parents PAH with OH or NO_3 radicals (in the presence of NO_2) in the gas phase as well as N_2O_5 or HNO_3 when parent PAH is associated with aerosols. In the tropics, an important source of particulate PAH and nitro-PAH is biomass burning used for clearings in forest and for making easier the harvesting of sugar cane. Brazil owns 25% of global sugar cane and is the major producer in the world. This burning produces soot, which remains for along time in the air and can cause respiratory diseases. This study was conducted in 3 cities in São Paulo State during sugar cane burning episodes. Back trajectories were calculated by University of São Paulo Trajectory Model for determination of air parcel trajectories over the sites. Atmospheric samples were collected on quartz fiber filters for 24 hours in high-volume sampler during one week. A Soxhlet apparatus filled with methylene chloride was used for extracting the filters. This residue was submitted to HPLC separation and the 3 obtained fractions (n-alkanes, PAH and nitro-PAH) were analyzed by both gas chromatography/flame ionization and gas chromatography/mass spectrometry detection. The isomers 2-, 3-, 8-nitrofluoranthene and 2-nitropyrene were identified and results show large differences between the sites. 2-nitropyrene/2-nitrofluoranthene ratios were calculated indicating the daytime reactions promoted by OH radicals.

Mabilia, R.; Cecinato, A.; Tomasi Scianò, M. C.; Vasconcellos, P.; Carvalho, L.; Mathos, L.; Franco, L.

2003-04-01

167

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

168

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

169

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

170

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

171

Airborne Measurements of atmospheric PAH's across Europe  

NASA Astrophysics Data System (ADS)

Atmospheric measurements of PAHs were taken aboard the DRL Falcon 20 during May 2001. A sampling system was designed to work aboard this aircraft platform. Particulate PAHs were collected on a glass fiber filter (GFF) with their gaseous component concentrated on a polyurethane foam sheets located behind the filter. Typically sampling volumes of between 20-50m^3 were collected which equated to a collection time of about 30minutes. In this way the distance travelled was kept within an acceptable level, about 60 nautical miles. The average concentrations of the data set for phenanthrene was 450 pg m-3 while values for many of the heavier PAH marker compounds used in the UK such as benzo(a)pyrene, diben(ah)anthracene were below the detection limits on all flights. The results will be discussed with consideration of location, altitude and airmass trajectory.

Davison, B.; Jaward, F.; Jones, K.; Lee, R.

2003-04-01

172

Abundances of Neutral and Ionized PAH Along The Lines-of-Sight of Diffuse and Translucent Interstellar Clouds  

NASA Technical Reports Server (NTRS)

The spectra of neutral and ionized PAHs isolated in the gas phase at low temperature have been measured in the laboratory under conditions that mimic interstellar conditions and are compared with a set of astronomical spectra of reddened, early type stars. The comparisons of astronomical and laboratory data provide upper limits for the abundances of neutral PAH molecules and ions along specific lines-of-sight. Something that is not attainable from infrared observations. We present the characteristics of the laboratory facility (COSmIC) that was developed for this study and discuss the findings resulting from the comparison of the laboratory data with high resolution, high S/N ratio astronomical observations. COSmIC combines a supersonic jet expansion with discharge plasma and cavity ringdown spectroscopy and provides experimental conditions that closely mimic the interstellar conditions. The column densities of the individual PAH molecules and ions probed in these surveys are derived from the comparison of the laboratory data with high resolution, high S/N ratio astronomical observations. The comparisons of astronomical and laboratory data lead to clear conclusions regarding the expected abundances for PAHs 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 quantitative searches of PAHs and complex organics in a variety of interstellar and circumstellar environments.

Salama, Farid; Galazutdinov, Gazinur; Krewloski, Jacek; Biennier, Ludovic; Beletsky, Yuri; Song, In-Ok

2013-01-01

173

The Emissions of PAHs and Heavy Metals from Co-Combustion of Petrochemical Sludge with Coal in CFB Incinerator  

NASA Astrophysics Data System (ADS)

The polycyclic aromatic hydrocarbons (PAHs) and heavy metals (Hg, Pb, Ni, Cr, Cu, Zn) emission characteristics in flue gas from co-combustion of petrochemical sludge and coal were investigated in a pilot-scale circulating fluidized bed (CFB) incinerator with a thermal input of 0.2 MW. Experimental results show that when mass ratio of petrochemical sludge/coal increases from 10% to 40%, PAHs, Hg and Zn emissions increase, while Pb and Ni emissions decrease. Mass mixing ratio has no obvious effect on the emissions of Cr and Cu. As combustion temperature increases, PAHs emission decreases at first and then increases, there is an optimum combustion temperature inhibiting PAHs formation, while emissions of Hg, Pb, Cu, Zn increase relatively rapidly. With Ca/S molar ratio increasing, PAHs, Hg, Pb, Ni, and Cu emissions decrease due to adsorption by calcium sorbents. Limestone is effective in adsorbing Pb and Ni, while lime is suitable to adsorb Hg and Cu. However, Ca/S molar ratio doesn't have much influence on the emissions of Cr and Zn. Some combustion parameters are recommended based on stable combustion and low pollutant emission.

Zhu, Ge; Zhao, Changsui; Chen, Huichao; Chen, Xiaoping; Liang, Cai

174

Secondary effects of catalytic diesel particulate filters: conversion of PAHs versus formation of nitro-PAHs.  

PubMed

Diesel particulate filters (DPFs) are a promising technology to detoxify diesel exhaust. However, the secondary combustion of diesel soot and associated compounds may also induce the formation of new pollutants. Diesel soot is rated as carcinogenic to humans and also acts as a carrier for a variety of genotoxic compounds such as certain polycyclic aromatic hydrocarbons (PAHs) or nitrated PAHs (nitro-PAHs). Furthermore, diesel exhaust contains considerable amounts of nitric oxide (NO), which can be converted to more powerful nitrating species like nitrogen dioxide (NO2), nitric acid (HNO3), and others. This mix of compounds may support nitration reactions in DPFs. Herein we report effects of two cordierite-based, monolithic, wall-flow DPFs on emissions of genotoxic PAHs and nitro-PAHs and compare these findings with those of a reporter gene bioassay sensitive to aryl hydrocarbons (AHs). Soot combustion was either catalyzed with an iron- or a copper/iron-based fuel additive (fuel-borne catalysts). A heavy duty diesel engine, operated according to the 8-stage ISO 8178/4 C1 cycle, was used as test platform. Emissions of all investigated 4- to 6-ring PAHs were reduced by about 40-90%, including those rated as carcinogenic. Emissions of 1- and 2-nitronaphthalene increased by about 20-100%. Among the 3-ring nitro-PAHs, emissions of 3-nitrophenanthrene decreased by about 30%, whereas 9-nitrophenanthrene and 9-nitroanthracene were found only after DPFs. In case of 4-ring nitro-PAHs, emissions of 3-nitrofluoranthene, 1-nitropyrene, and 4-nitropyrene decreased by about 40-60% with DPFs. Total AH-receptor (AHR) agonist concentrations of diesel exhaust were lowered by 80-90%, when using the iron- and copper-based DPFs. The tested PAHs accounted for < 1% of the total AHR-mediated response, indicating that considerable amounts of other aryl hydrocarbons must be present in filtered and unfiltered exhaust. We conclude that both DPFs detoxified diesel exhaust with respect to total aryl hydrocarbons, including the investigated carcinogenic PAHs, but we also noticed a secondary formation of selected nitro-PAHs. Nitration reactions were found to be stereoselective with a preferential substitution of hydrogen atoms at peri-positions. The stereoisomers obtained are related to combustion chemistry, but differ from those formed upon atmospheric nitration of PAHs. PMID:18546721

Heeb, Norbert V; Schmid, Peter; Kohler, Martin; Gujer, Erika; Zennegg, Markus; Wenger, Daniela; Wichser, Adrian; Ulrich, Andrea; Gfeller, Urs; Honegger, Peter; Zeyer, Kerstin; Emmenegger, Lukas; Petermann, Jean-Luc; Czerwinski, Jan; Mosimann, Thomas; Kasper, Markus; Mayer, Andreas

2008-05-15

175

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...

176

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

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

177

Thrombosis, platelets, microparticles, and PAH: More than clot  

PubMed Central

Pulmonary arterial hypertension (PAH) is a progressive disease that involves pathological remodeling, vasoconstriction, and thrombosis. Alterations in hemostasis, coagulation, and platelet activation are consistently observed in PAH patients. Microparticles derived from platelets, inflammatory cells, and the endothelium are an increasingly well-recognized signal in a variety of cardiovascular diseases, including PAH. This review will focus on the role of coagulation, thrombosis, platelet activation, and microparticles in the pathology and progression of PAH. PMID:24747560

Lannan, Katie L.; Phipps, Richard P.; White, R. James

2015-01-01

178

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

PubMed

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

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

2013-01-15

179

Bioacessibility of PAHs in Fuel Soot Assessed by an in Vitro Digestive Model: Effect of Including an Absorptive Sink.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) associated with soot or black carbon can enter the human digestive tract by unintentional ingestion of soil or other particles. This study investigated the bioaccessibility of 11 PAHs in a composite fuel soot sample using an in vitro digestive model that included silicone sheet as an absorptive sink during the small intestinal digestion stage. The sheet was meant to simulate the passive transfer of PAHs in lumen fluid across the small intestinal epithelium, which was postulated to promote desorption of labile PAHs from the soot by steepening the soot-fluid concentration gradient. We show that the presence of silicone sheet during a 4 h default digestion time significantly increased the apparent bioaccessible fraction (Bapp, %), defined as the sum in the sheet and digestive fluid relative to the total PAH determined. The ability to increase Bapp for most PAHs leveled off above a sheet-to-soot ratio of 2.0 g per 50 mg, indicating that the sheet is an effective absorptive sink and promotes desorption in the mentioned way. Enhancement of Bapp by the sheet correlated positively with the octanol-water partition coefficient (Kow), even though the partition coefficient of PAH between sheet and digestive fluid (which contains bile acid micelles) correlated negatively with Kow. It was hypothesized that PAHs initially in the soot exist in labile and nonlabile states. The fraction of labile PAH still sorbed to the soot residue after digestion, and the maximum possible (limiting) bioaccessibility (Blim) could be estimated by varying the sheet-to-soot ratio. We show conclusively that the increase in bioccessibility due to the presence of the sheet is accounted for by a corresponding decrease in fraction of labile PAH still sorbed to the soot. The Blim ranged from 30.8 to 62.4%, independent of molecular size. The nonlabile fraction of individual PAHs (69.2-37.6% in this case) is therefore large and needs to be taken into account in risk assessment. PMID:25692464

Zhang, Yanyan; Pignatello, Joseph J; Tao, Shu; Xing, Baoshan

2015-03-17

180

Carcinogenic PAH in waterpipe charcoal products  

Microsoft Academic Search

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

Elizabeth Sepetdjian; Najat Saliba; Alan Shihadeh

2010-01-01

181

PAH Sorption Mechanism and Partitioning Behavior in  

E-print Network

PAH Sorption Mechanism and Partitioning Behavior in Lampblack-Impacted Soils from Former Oil of crude oil at high temperatures in the gas-making operation and is coated or impregnated with oil carbon with soot-like structures. A free-phase aromatic oil may be present in some of the lampblack soils

Zare, Richard N.

182

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 ...

183

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

184

Particle-Scale Investigation of PAH Desorption Kinetics and  

E-print Network

- density coal- and wood-derived fraction with 62% of total PAHs and a heavier-density sand, silt, and clay model were used to describe the thermal desorption of PAHs for four molecular weight classes. PAH.e., in the range of 37-41 kJ/ mol for molecular weight 202. Among the desorption models tested, a spherical

185

Rapid persulfate oxidation predicts PAH bioavailability in soils and sediments  

Microsoft Academic Search

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

Chiel Cuypers; Tim Grotenhuis; Jan Joziasse; Wim Rulkens

2000-01-01

186

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

187

Assessment of PAH Levels in Atmospheric Particulates from  

E-print Network

. Toxic equivalent values were similar for both sets of samples (0.29-0.30 ng BaP TEQ/m 3 ). High molecular weight PAHs exhibited a tri-modal distribution at molecular weight PAHs were associated with the summer months, while higher molecular weight PAHs were

188

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

189

Exploratory data analysis of PAH, nitro-PAH and hydroxy-PAH concentrations in atmospheric PM10-bound aerosol particles. Correlations with physical and chemical factors  

NASA Astrophysics Data System (ADS)

A method is proposed to determine PAHs, OH-PAHs and nitro-PAHs in samples of PM10 particulate matter based on liquid chromatography with fluorescence detection, and applied to quantify such compounds over a 14-month period in a semiurban area of a large city (Madrid, Spain). A clear seasonal trend was observed in the levels of the compounds. The mean overall concentration of all the PAHs determined was 1250 pg m-3; with levels rising in the colder months to 2062 pg m-3 and descending in the warm months to 725 pg m-3. The same effect was observed for the OH-PAHs, showing a mean of 83 pg m-3 and values of 153 pg m-3 and 36 pg m-3 in the colder and warmer months, and for the nitro-PAHs, with a mean of 132 pg m-3 and levels of 162 pg m-3 and of 112 pg m-3 in the colder and warmer months, respectively. These trends were confirmed in the statistical analysis, which clearly revealed the difference between PAH levels in the months April-September compared to October-December or January-March. Correlations were also found between PAH patterns and those of their hydroxy- and nitro derivatives, as well as between both derivatives. Negative correlation was observed between O3 and OH-PAH levels and direct correlation between the presence of nitrogen oxides in the atmosphere and nitro-PAHs in the particulate matter.

Barrado, Ana Isabel; García, Susana; Castrillejo, Yolanda; Barrado, Enrique

2013-03-01

190

Effects of low concentration biodiesel blends application on modern passenger cars. Part 3: impact on PAH, nitro-PAH, and oxy-PAH emissions.  

PubMed

This study explores the impact of five different types of methyl esters on polycyclic aromatic hydrocarbon (PAH), nitrated-PAH and oxygenated PAH emissions. The measurements were conducted on a chassis dynamometer, according to the European regulation. Each of the five different biodiesels was blended with EN590 diesel at a proportion of 10-90% v/v (10% biodiesel concentration). The vehicle was a Euro 3 compliant common-rail diesel passenger car. Emission measurements were performed over the NEDC and compared with those of the real traffic-based Artemis driving cycles. The experimental results showed that the addition of biodiesel led to some important increases in low molecular-weight PAHs (phenanthrene and anthracene) and to both increases and reductions in large PAHs which are characterised by their carcinogenic and mutagenic properties. Nitro-PAHs were found to reduce with biodiesel whereas oxy-PAH emissions presented important increases with the biodiesel blends. The impact of biodiesel source material was particularly clear on the formation of PAH compounds. It was found that most PAH emissions decreased as the average load and speed of the driving cycle increased. Cold-start conditions negatively influenced the formation of most PAH compounds. A similar trend was observed with particulate alkane emissions. PMID:20083330

Karavalakis, Georgios; Fontaras, Georgios; Ampatzoglou, Dimitrios; Kousoulidou, Marina; Stournas, Stamoulis; Samaras, Zissis; Bakeas, Evangelos

2010-05-01

191

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

E-print Network

surface soil · Air · Tire tracking Sealant applied by contractors in October 2007 #12;Results ­ Stormwater/L 4.39 g/L #12;PAH (Sum 16) Concentrations in Composite Stormwater Samples - Not normalized to flow ug/l March 19, 2008 1 inch of rain (30,000 liters) Flow(m3/s) 2.3 g PAHs #12;0.1 1 10 100 1000 10000

192

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

193

Rapid persulfate oxidation predicts PAH bioavailability in soils and sediments  

SciTech Connect

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

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

2000-05-15

194

Effect of rhamnolipids on the uptake of PAHs by ryegrass.  

PubMed

A hydroponic experiment was conducted to investigate the effect of rhamnolipids, a biosurfactant, on the uptake of polycyclic aromatic hydrocarbons (PAHs) by ryegrass. Results showed that rhamnolipids could enhance the uptake of PAHs by ryegrass roots. With increasing concentration of rhamnolipids, the PAH content in ryegrass roots initially increased and then decreased, while the PAH content in ryegrass shoots did not change. Batch studies also showed that the sorption of phenanthrene by fresh ryegrass roots was dependent on rhamnolipid concentration and showed the same trends as the uptake experiment. The increase of permeability of ryegrass root cells with the increase of rhamnolipid concentration may lead to the initial enhancement of PAH content in ryegrass roots, and the decrease of PAH adsorption onto the root surface with further increase of rhamnolipids led to the decrease of PAH content in ryegrass roots. PMID:18281132

Zhu, Lizhong; Zhang, Ming

2008-11-01

195

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.

196

Benzo[b]fluoranthene, a potential alternative to benzo[a]pyrene as an indicator of exposure to airborne PAHs in the vicinity of Söderberg aluminum smelters.  

PubMed

Benzo[b]fluoranthene (B[b]F) was used in relative abundance ratios (RARs), a parameter obtained by dividing the concentration of individual polycyclic aromatic hydrocarbons (PAHs) found in a given sample by the concentration of B[b]F in the same sample. The B[b]F RARs were derived for PAH concentrations measured at stacks and sampling stations in the vicinity of two Söderberg aluminum horizontal stud smelters (HSSs). The samples collected were analyzed by high-performance liquid chromatography using UV and fluorescence detection. A total of 15 PAHs were analyzed, but, due to the inefficiency of the sampling method used in collecting gaseous PAHs, only particulate PAHs were considered. Comparisons between the B[b]F RARs obtained simultaneously at the source (stack) and those obtained at sampling stations at the two smelters showed that B[b]F degrades more slowly than or at the same rate as most other particulate PAHs monitored. Twenty-three months of urban sampling in the vicinity of one of the aluminum HSSs are also presented, and the results indicate that B[b]F is more stable than all other particulate PAHs investigated. Sampling conducted during a smelter shutdown period confirmed that B[b]F was a much better marker of this source than was benzo[a]pyrene (B[a]P), the usual indicator. The remarkable stability of the benzo[k]fluoranthene (B[k]F)/B[b]F ratio is also discussed. PMID:11140138

Aubin, S; Farant, J P

2000-12-01

197

PAHs, NITRO-PAHs, HOPANES, AND STERANES IN LAKE TROUT FROM LAKE MICHIGAN  

PubMed Central

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 (?9PAH) 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 (?9NPAH) 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 (?5Sterane) and total hopane (?2Hopane) 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.

2015-01-01

198

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

199

Phenylalanine hydroxylase (PAH) from the lower eukaryote Leishmania major  

PubMed Central

Aromatic amino acid hydroxylases (AAAH) typically use tetrahydrobiopterin (H4B) as the cofactor. The protozoan parasite Leishmania major requires biopterin for growth and expresses strong salvage and regeneration systems to maintain H4B levels. Here we explored the consequences of genetic manipulation of the sole L. major phenylalanine hydroxylase (PAH) to explore whether it could account for the Leishmania H4B requirement. L. major PAH resembles AAAHs of other organisms, bearing eukaryotic-type domain organization, and conservation of key catalytic residues including those implicated in pteridine binding. A pah? null mutant and an episomal complemented overexpressing derivative (pah?/+PAH) were readily obtained, and metabolic labeling studies established that PAH was required to hydroxylate Phe to Tyr. Neither WT nor overexpressing lines were able to hydroxylate radiolabeled tyrosine or tryptophan, nor to synthesize catecholamines. WT but not pah? parasites showed reactivity with an antibody to melanin when grown with L-3,4-dihydroxyphenylalanine (L-DOPA), although the reactive product is unlikely to be melanin sensu strictu. WT was auxotrophic for Phe, Trp and Tyr, suggesting that PAH activity was insufficient to meet normal Tyr requirements. However, pah? showed an increased sensitivity to Tyr deprivation, while the pah?/+PAH overexpressor showed increased survival and could be adapted to grow well without added Tyr. pah? showed no alterations in H4B-dependent differentiation, as established by in vitro metacyclogenesis, or survival in mouse or macrophage infections. Thus Leishmania PAH may mitigate but not alleviate Tyr auxotrophy, but plays no essential role in the steps of the parasite infectious cycle. These findings suggest PAH is unlikely to explain the Leishmania requirement for biopterin. PMID:20887755

Lye, Lon-Fye; Kang, Song Ok; Nosanchuk, Joshua D.; Casadevall, Arturo; Beverley, Stephen M.

2010-01-01

200

[PAH Cations as Viable Carriers of DIBs  

NASA Technical Reports Server (NTRS)

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

Snow, Ted

1998-01-01

201

Photodestruction of PAHs in Planetary Nebulae  

Microsoft Academic Search

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

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

2005-01-01

202

Theoretical evaluation of PAH dications properties  

E-print Network

Aims. We present a systematic theoretical study on 40 polycyclic aromatic hydrocarbons dications (PAHs++) containing up to 66 carbon atoms. Methods. We performed our calculations using well established quantum-chemical techniques in the framework of the density functional theory (DFT) to obtain the electronic ground-state properties, and of the time-dependent DFT (TD-DFT) to evaluate the excited\\textendash state properties. Results. For each PAH++ considered we computed the absolute visible-UV photo-absorption cross-section up to about 30 eV. We also evaluated their vibrational properties and compared them to those of the corresponding neutral and singly-ionised species. We estimated the adiabatic and vertical second ionisation energy DeltaI through total energy differences. Conclusions. The DeltaI values obtained fall in the energy range 8-13 eV, confirming that PAHs could reach the doubly-ionised state in HI regions. The total integrated IR absorption cross-sections show a marked increase upon ionization, b...

Malloci, G; Mulas, G

2006-01-01

203

Carbon in The Universe: PAHs and Clusters  

NASA Technical Reports Server (NTRS)

Following the initial demonstration of this new technique (Science 265 1686 (1994)) and its application to a series of neutral PAHs which have been proposed as condidates for the UIRs (Nature 380, 227 (1996)), we have concentrated on two major aspects of this project. 1. Developing a detailed model for infrared emission spectra of a collection of highly excited PAH molecules, in which experimental bandshapes and temperature-dependent redshifts are used in conjunction with ab initio vibrational frequencies and intensities to simulate the UIR bands. This shows that a collection of nine different cations (as large as ovalene) reproduce the UIR features better than do a collection of the corresponding neutrals, but a detailed match with the UIRs is not obtained. 2. Construction of SPIRES apparatus for the study of PAH ion emission spectra. The design of this experiment is shown and described. Unfortunately a disasterous accident occurred just as we were preparing to start the testing of the ion apparatus. A vacuum implosion occurred, destroying the liquid He cooled monochromator. It has taken us nearly one full year to reconstruct this, and we arc only now in the final testing of the new system. We expect to try the ion experiments by the end of summer.

Saykally, Richard J.

1997-01-01

204

Sorption and chemical transformation of PAHs on coal fly ash  

SciTech Connect

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

Mamantov, G.; Wehry, E.L.

1991-01-01

205

Quantitative characterization of PAHs in burn residue and soot samples and differentiation of pyrogenic PAHs from petrogenic PAHs -- The 1994 Mobile burn study  

Microsoft Academic Search

Several mesoscale burns were conducted in 1994 in Mobile Bay, AL, to study various aspects of diesel fuel burning in situ. The target PAHs in the diesel, residue, and soot samples collected during each burn were quantitatively characterized by GC\\/MS. A simple model based on mass balance of individual petroleum PAHs pre- and postburn was proposed to estimate the destruction

Zhendi Wang; Merv Fingas; Y. Y. Shu; Lise Sigouin; Michael Landriault; Pat Lambert; Rod Turpin; Phil Campagna; Joseph Mullin

1999-01-01

206

Mitigation of PAH and Nitro-PAH Emissions from Nonroad Diesel Engines.  

PubMed

More stringent emission requirements for nonroad diesel engines introduced with U.S. Tier 4 Final and Euro Stage IV and V regulations have spurred the development of exhaust aftertreatment technologies. In this study, several aftertreatment configurations consisting of diesel oxidation catalysts (DOC), diesel particulate filters (DPF), Cu zeolite-, and vanadium-based selective catalytic reduction (SCR) catalysts, and ammonia oxidation (AMOX) catalysts are evaluated using both Nonroad Transient (NRTC) and Steady (8-mode NRSC) Cycles in order to understand both component and system-level effects of diesel aftertreatment on emissions of polycyclic aromatic hydrocarbons (PAH) and their nitrated derivatives (nitro-PAH). Emissions are reported for four configurations including engine-out, DOC+CuZ-SCR+AMOX, V-SCR+AMOX, and DOC+DPF+CuZ-SCR+AMOX. Mechanisms responsible for the reduction, and, in some cases, the formation of PAH and nitro-PAH compounds are discussed in detail, and suggestions are provided to minimize the formation of nitro-PAH compounds through aftertreatment design optimizations. Potency equivalency factors (PEFs) developed by the California Environmental Protection Agency are then applied to determine the impact of aftertreatment on PAH-derived exhaust toxicity. Finally, a comprehensive set of exhaust emissions including criteria pollutants, NO2, total hydrocarbons (THC), n-alkanes, branched alkanes, saturated cycloalkanes, aromatics, aldehydes, hopanes and steranes, and metals is provided, and the overall efficacy of the aftertreatment configurations is described. This detailed summary of emissions from a current nonroad diesel engine equipped with advanced aftertreatment can be used to more accurately model the impact of anthropogenic emissions on the atmosphere. PMID:25668360

Liu, Z Gerald; Wall, John C; Ottinger, Nathan A; McGuffin, Dana

2015-03-17

207

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

PubMed

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

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

2006-06-01

208

Distribution of polycyclic aromatic hydrocarbons (PAH's) in marsh sediments, Iraq  

SciTech Connect

Recently there has been a growing concern in the release of harmful organics into the environment. Carcinogenic polycyclic aromatic hydrocarbons (PAH's) are a class of compounds of interset due to their possible harmful effects to man as well as organisms. Anthropogenic PAH's may reach aquatic environment as a result of both industrial and domestic effluents, deposition of airborne particles, surface runoff and oil spillage. Having a relatively low water solubility and high affinity to sorb to the suspended particulate matter, most of the PAH's introduced to the aquatic environment tend to accumulate in bottom sediments. Sedimentary PAH's may thus provide a record of the input and history of these pollutants. Consequently, the distribution of PAH's in aquatic sediments have received considerable attention. The purpose of the present work was to establish the distribution of PAH's in the sediments of the marsh region located in southern Iraq.

Al-Saad, H.T.; Al-Timari, A.A. (Univ. of Basrah (Iraq))

1989-12-01

209

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

210

Simplifying site assessment of PAH using immunoassay directed field screening  

SciTech Connect

Polycyclic aromatic hydrocarbons (PAH) are carcinogenic and mutagenic chemicals found in combustion products and industrial waste materials. The carcinogenic nature of PAHs has led state and federal agencies to control their levels in the environment. Until recently, site assessment of PAH levels in soil was limited by the high cost and long turnaround time associated with analysis methods used in commercial analytical laboratories. The recent development of PAH immunoassays provides a rapid and cost effective alternative to the traditional analytical methods. One such immunoassay was developed as a part of the D TECH tm line of environmental detection systems. This competitive immunoassay uses anti-PAH antibodies immobilized on latex particles. Antibody binding to an enzyme labeled PAH analog is inhibited by free PAH extracted from soil samples or contained in water samples. The immunoassay detects the majority of compounds on the EPA list of 16 PAH priority pollutants below the ppm level without cross reacting with BTEX, PCBs and other similar compounds. Field samples of PAH were collected at both petrogenic and pyrolytic sites of contamination and the PAH concentrations were determined by both the immunoassay and the EPA SW-846 GC/MS method 8270. Test results correlated between the two methods and the low number of false negative and false positive results confirmed the assay`s specificity for PAH. The immunoassay provides the advantages of rapid, on site analysis, and minimum sample preparation. Use of the immunoassay results in a significant savings in the cost of analysis because the cost per assay is lower than commercial analysis and only positive samples require additional confirmation by instrumental techniques. The simple format of the immunoassay allows personnel with minimal training to reliably and accurately determine the PAH content of soils.

Mullenix, M.C.; Hudak, R.T.; Melby, J.M.; Stave, J.W. [Strategic Diagnostics Inc., Newark, DE (United States)

1995-12-31

211

Evaluation of an exposure assay to measure uptake of sediment PAH by fish.  

PubMed

The ecological risks of polynuclear aromatic hydrocarbons (PAH) in aquatic sediments will vary with both toxicity and bioavailability to aquatic biota. While there are standardized protocols to test the acute toxicity of sediment-borne compounds to aquatic invertebrates, there are none for assessing bioavailability to fish. We found that sediment-borne PAH caused an exposure-dependent induction of cytochrome P450 (CYP1A) enzymes in rainbow trout (Oncorhynchus mykiss) fingerlings exposed in semi-static 96 h bioassays, as shown by increased activity of ethoxyresorufin-o-deethylase (EROD). Assuming that PAH are taken up by trout due to partitioning from organic and inorganic constituents of sediments, we tested the effect of different test variables on bioaccumulation using induction as an index of exposure. EROD activity increased with exposure of fish to increasing volumes of sediments containing PAH, i.e., with increasing ratios of sediment to water. Uptake of single compounds from sandy sediments did not differ from uptake from clay or low organic (7% LOI - loss on ignition) sediments, but decreased when organic content was very high (58% LOI). Maximum induction was observed within 24 h of exposure and at 7.5 degrees C relative to 15, 22, or 28 degrees C. Storage and handling techniques had minor effects on sediment EROD induction potency. Absolute EROD activity was greater in white sucker (Catostomus commersoni) a benthic species, than in trout, a pelagic species. However, when basal (negative control) activity was accounted for, there was no difference in response between the species. Together, these experiments provide a basis for developing a standard protocol to test the bioavailability to fish of sediment-borne PAH. PMID:16779608

Fragoso, Nuno M; Hodson, Peter V; Zambon, Silvia

2006-05-01

212

UV-VIS absorption spectroscopy of jet-cooled PAHs  

NASA Astrophysics Data System (ADS)

We use cavity ring-down laser absorption spectroscopy to probe supersonic expansions of rare gases seeded with PAHs. The principal means of transferring solid PAH samples to the gas phase is heating, which we have applied to study rather light PAHs like anthracene (C14H10), but also the larger benzo[g,h,i]perylene (C22H12). As heating is expected to become less effective for vaporizing increasingly larger PAHs, laser vaporization is being explored for this purpose. Results are discussed within the framework of the search for carriers of diffuse interstellar bands.

Rouillé, G.; Arold, M.; Huisken, F.; Henning, Th.

2007-12-01

213

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

214

Protonated PAHs as carriers of diffuse interstellar bands  

NASA Astrophysics Data System (ADS)

We report the first results of Time-dependent Density Functional Theory calculations of electronic transitions of protonated stable neutral polycyclic aromatic hydrocarbon (PAH) molecules. Unlike most neutral closed-shell PAHs which generally absorb strongly in the ultraviolet (UV) or near-UV, the corresponding isoelectronic protonated forms of PAH molecules such as coronene and ovalene are predicted to have absorptions in the visible spectral region. Combining this with other astrophysical, chemical and physical aspects, it is concluded that the protonated forms of PAHs represent a strong class of candidate carriers of diffuse interstellar bands.

Pathak, A.; Sarre, P. J.

2008-11-01

215

PAH intermediates: Links between the atmosphere and biological systems.  

PubMed

China is now the world's largest emitter of polycyclic aromatic hydrocarbons (PAHs). In addition, PAHs, and their reactive intermediates, undergo trans-Pacific atmospheric transport to the Western U.S. The objectives of our research are to predict, identify and quantify novel PAH intermediates in the atmosphere and biological systems, using computational methods, as well as laboratory and field experiments. Gaussian is used to predict the thermodynamic properties of parent structure PAHs, as well as the associated nitro-, oxy-, and hydroxy-PAH intermediates. Based on these predictions, state-of-the-art analytical chemistry techniques are used to identify and quantify these potential intermediates on Asian particulate matter before and after reaction in a continuous flow photochemical reactor. These same techniques are used to identify the relative proportion of PAH intermediates in PAH source regions (such as Beijing, China) and during long-range atmospheric transport to the Western U.S. PAH personal exposure studies in China and the Confederated Tribes of the Umatilla Indian Reservation in Oregon will be used to assess the similarities and differences in the PAH intermediates in biological systems relative to the atmosphere. PMID:20849837

Simonich, Staci L Massey; Motorykin, Oleksii; Jariyasopit, Narumol

2011-06-30

216

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

PubMed

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 (approximately 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. PMID:19731689

Deepthike, Halambage Upul; Tecon, Robin; Van Kooten, Gerry; Van der Meer, Jan Roelof; Harms, Hauke; Wells, Mona; Short, Jeffrey

2009-08-01

217

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

218

Integrated diagnostics  

NASA Technical Reports Server (NTRS)

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

Hunthausen, Roger J.

1988-01-01

219

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

220

Testing the ``strong'' PAHs hypothesis. I. Profile invariance of electronic transitions of interstellar PAH cations  

NASA Astrophysics Data System (ADS)

The so-called ``strong'' Polycyclic Aromatic Hydrocarbons (PAHs) hypothesis postulates that isolated PAHs, which are thought to be the carriers of the Unidentified Infrared Bands, ought to be also responsible for a large number of Diffuse Interstellar Bands (DIBs). In this framework, the spectral profile of such DIBs should be due to unresolved rotational structure of vibronic absorption bands, the rotation of the molecule being by and large governed by the interaction with the interstellar radiation field. In this paper we quantitatively test the above hypothesis against the observational constraint of DIBs profile invariance, by using Monte-Carlo methods to model the photophysics of a prototypical interstellar PAH, namely the ovalene cation (C32H14+). Our results show that the predicted rotational band profiles are remarkably insensitive to both the ambient conditions and the assumed values of some poorly known parameters. The present model therefore offers a quantitative link between any given PAH and the observed DIB profiles, providing a valuable tool for molecular identification.

Malloci, G.; Mulas, G.; Benvenuti, P.

2003-11-01

221

Composition and Integrity of PAHs, Nitro-PAHs, Hopanes and Steranes In Diesel Exhaust Particulate Matter  

PubMed Central

Diesel exhaust particulate matter contains many semivolatile organic compounds (SVOCs) of environmental and health significance. This study investigates the composition, emission rates, and integrity of 25 SVOCs, including polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs (NPAHs), and diesel biomarkers hopanes and steranes. Diesel engine particulate matter (PM), generated using an engine test bench, three engine conditions, and ultra-low sulfur diesel (ULSD), was collected on borosilicate glass fiber filters. Under high engine load, the PM emission rate was 0.102 g/kWh, and emission rate of ?PAHs (10 compounds), ?NPAHs (6 compounds), ?hopanes (2 compounds), and ?steranes (2 compounds) were 2.52, 0.351, 0.02 ~ 2 and 1?g/kWh, respectively. Storage losses were evaluated for three cases: conditioning filters in clean air at 25 °C and 33% relative humidity (RH) for 24 h; storing filter samples (without extraction) wrapped in aluminum foil at 4 °C for up to one month; and storing filter extracts in glass vials capped with Teflon crimp seals at 4 °C for up to six months. After conditioning filters for 24 h, 30% of the more volatile PAHs were lost, but lower volatility NPAHs, hopanes and steranes showed negligible changes. Storing wrapped filters and extracts at 4 °C for up to one month did not lead to significant losses, but storing extracts for five months led to significant losses of PAHs and NPAHs; hopanes and steranes demonstrated greater integrity. These results suggest that even relatively brief filter conditioning periods, needed for gravimetric measurements of PM mass, and extended storage of filter extracts can lead to underestimates of SVOC concentrations. Thus, SVOC sampling and analysis protocols should utilize stringent criteria and performance checks to identify and limit possible biases occurring during filter and extract processing. PMID:24363468

Huang, Lei; Bohac, Stanislav V.; Chernyak, Sergei M.; Batterman, Stuart A.

2013-01-01

222

Composition and Integrity of PAHs, Nitro-PAHs, Hopanes and Steranes In Diesel Exhaust Particulate Matter.  

PubMed

Diesel exhaust particulate matter contains many semivolatile organic compounds (SVOCs) of environmental and health significance. This study investigates the composition, emission rates, and integrity of 25 SVOCs, including polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs (NPAHs), and diesel biomarkers hopanes and steranes. Diesel engine particulate matter (PM), generated using an engine test bench, three engine conditions, and ultra-low sulfur diesel (ULSD), was collected on borosilicate glass fiber filters. Under high engine load, the PM emission rate was 0.102 g/kWh, and emission rate of ?PAHs (10 compounds), ?NPAHs (6 compounds), ?hopanes (2 compounds), and ?steranes (2 compounds) were 2.52, 0.351, 0.02 ~ 2 and 1?g/kWh, respectively. Storage losses were evaluated for three cases: conditioning filters in clean air at 25 °C and 33% relative humidity (RH) for 24 h; storing filter samples (without extraction) wrapped in aluminum foil at 4 °C for up to one month; and storing filter extracts in glass vials capped with Teflon crimp seals at 4 °C for up to six months. After conditioning filters for 24 h, 30% of the more volatile PAHs were lost, but lower volatility NPAHs, hopanes and steranes showed negligible changes. Storing wrapped filters and extracts at 4 °C for up to one month did not lead to significant losses, but storing extracts for five months led to significant losses of PAHs and NPAHs; hopanes and steranes demonstrated greater integrity. These results suggest that even relatively brief filter conditioning periods, needed for gravimetric measurements of PM mass, and extended storage of filter extracts can lead to underestimates of SVOC concentrations. Thus, SVOC sampling and analysis protocols should utilize stringent criteria and performance checks to identify and limit possible biases occurring during filter and extract processing. PMID:24363468

Huang, Lei; Bohac, Stanislav V; Chernyak, Sergei M; Batterman, Stuart A

2013-08-01

223

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

224

Abundances of Neutral and Ionized PAH Along The Lines-of-Sight of Diffuse and Translucent Interstellar Clouds  

NASA Astrophysics Data System (ADS)

The spectra of neutral and ionized PAHs isolated in the gas phase at low temperature have been measured in the laboratory under conditions that mimic interstellar conditions and are compared with a set of astronomical spectra of reddened, early type stars. The comparisons of astronomical and laboratory data provide upper limits for the abundances of neutral PAH molecules and ions along specific lines-of-sight. Something that is not attainable from infrared observations. We present the characteristics of the laboratory facility (COSmIC) that was developed for this study and discuss the findings resulting from the comparison of the laboratory data with high resolution, high S/N ratio astronomical observations. COSmIC combines a supersonic jet expansion with discharge plasma and cavity ringdown spectroscopy and provides experimental conditions that closely mimic the interstellar conditions. The column densities of the individual PAH molecules and ions probed in these surveys are derived from the comparison of the laboratory data with high resolution, high S/N ratio astronomical observations. The comparisons of astronomical and laboratory data lead to clear conclusions regarding the expected abundances for PAHs 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 quantitative searches of PAHs and complex organics in a variety of interstellar and circumstellar environments. Acknowledgements: F.S. acknowledges the support of the Astrophysics Research and Analysis Program of the NASA Space Mission Directorate and the technical support provided by R. Walker at NASA ARC. J.K. acknowledges the financial support of the Polish State. The authors are deeply grateful to the ESO archive as well as to the ESO staff members for their active support.

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

2013-06-01

225

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...

226

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

227

Dissipation of PAHs in saturated, dredged sediments: a field trial.  

PubMed

Sediments dredged from navigable rivers often contain elevated concentrations of recalcitrant, potentially toxic organic compounds such as polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). The presence of these compounds often requires that the sediments be stored in fully contained disposal facilities. A 3-year field study was conducted at the Jones Island disposal facility in Milwaukee, Wisconsin, to compare bioremediation of PAHs in contaminated dredged sediments in the absence of plants to phytoremediation with Salix nigra (black willow) (SX61), Spartina pectinata (prairie cord grass), Carex aquatalis (lake sedge), Lolium multiflorum (annual rye), and Scirpus fluviatilis (bulrush). Nine PAHs were detected initially in the sediments. Over the 3-year experiment, acenaphthene dissipation ranged from 94% to 100%, whereas anthracene, benzo[a]pyrene and indo[1,2,3-cd]pyrene generally had modest decreases in concentration (0-30% decrease). The remaining five PAHs ranged in degree of disappearance from 23% to 82%. Planted treatments did not enhance PAH dissipation relative to those without plants, but treatments with high biomass yield and high transpiration plant species had significantly less removal of PAHs than unplanted controls. Significant, negative correlations between nitrogen removal and decreases in PAH concentration suggest that competition for nutrients between plants and microorganisms may have impeded the microbial degradation of PAHs in the rhizosphere of the more rapidly growing plant species. PMID:18547603

Smith, K E; Schwab, A P; Banks, M K

2008-08-01

228

Imaging of the PAH Emission Bands in the Orion Bar  

NASA Technical Reports Server (NTRS)

The infrared spectrum of many planetary nebulae, HII regions, galactic nuclei, reflection nebulae, and WC stars are dominated by a set of narrow and broad features which for many years were called the "unidentified infrared bands". These bands have been attributed to several carbon-rich molecular species which all contain only carbon and hydrogen atoms, and fall into the class of PAH molecules or are conglomerates of PAH skeletons. If these bands are from PAHs, then PAHs contain 1-10% of the interstellar carbon, making them the most abundant molecular species in the interstellar medium after CO. From ground based telescopes, we have studied the emission bands assigned to C-H bond vibrations in PAHs (3.3, 11.3 microns) in the Orion Bar region, and showed that their distribution and intensities are consistent with a quantitative PAH model. We have recently obtained spectral images of the Orion Bar from the KAO at 6.2 and 7.7 microns using a 128 x 128 Si:Ga array camera in order to study the C-C modes of the PAH molecules. We will show these new data along with our existing C-H mode data set, and make a quantitative comparison of the data with the existing PAH model.

Bregman, Jesse; Harker, David; Rank, David; Temi, Pasqiale; Morrison, David (Technical Monitor)

1994-01-01

229

Profiles of PAH emission from steel and iron industries  

Microsoft Academic Search

In order to characterize the polycyclic aromatic hydrocarbons (PAHs) emission from steel and iron industries, this study measured the stack emission of twelve steel and iron plants in southern Taiwan to construct a set of source fingerprints. The study sampled the emissions by the USEPA's sampling method 5 with the modification of Graseby for the gas and particulate phase PAH

Hsi-Hsien Yang; Soon-Onn Lai; Lien-Te Hsieh; Hung-Junt Hsueh; Tze-Wen Chi

2002-01-01

230

Are Urinary PAHs Biomarkers of Controlled Exposure to Diesel Exhaust?  

EPA Science Inventory

Urinary polycyclic aromatic hydrocarbons (PAHs) were evaluated as possible biomarkers of exposure to diesel exhaust (DE) in two controlled-chamber studies. We report levels of 14 PAHs from 28 subjects in urine that were collected before, immediately after and the morning after ex...

231

Solubilization, solution equilibria, and biodegradation of PAH's under thermophilic conditions.  

PubMed

Biodegradation rates of PAHs are typically low at mesophilic conditions and it is believed that the kinetics of degradation is controlled by PAH solubility and mass transfer rates. Solubility tests were performed on phenanthrene, fluorene and fluoranthene at 20 degrees C, 40 degrees C and 60 degrees C and, as expected, a significant increase in the equilibrium solubility concentration and of the rate of dissolution of these polycyclic aromatic hydrocarbons (PAHs) was observed with increasing temperature. A first-order model was used to describe the PAH dissolution kinetics and the thermodynamic property changes associated with the dissolution process (enthalpy, entropy and Gibb's free energy of solution) were evaluated. Further, other relevant thermodynamic properties for these PAHs, including the activity coefficients at infinite dilution, Henry's law constants and octanol-water partition coefficients, were calculated in the temperature range 20-60 degrees C. In parallel with the dissolution studies, three thermophilic Geobacilli were isolated from compost that grew on phenanthrene at 60 degrees C and degraded the PAH more rapidly than other reported mesophiles. Our results show that while solubilization rates of PAHs are significantly enhanced at elevated temperatures, the biodegradation of PAHs under thermophilic conditions is likely mass transfer limited due to enhanced degradation rates. PMID:16934313

Viamajala, Sridhar; Peyton, Brent M; Richards, Lee A; Petersen, James N

2007-01-01

232

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...

233

Fungal PAH-metabolites resist mineralization by soil microorganisms.  

PubMed

This study investigated the mineralization of water-soluble polycyclic aromatic hydrocarbon (PAH) metabolites produced by the soil fungus Cunninghamella elegans. Eleven soil fungi were screened for their ability to metabolize (14)C-phenanthrene, (14)C-fluoranthene, and (14)C-pyrene into water-soluble compounds. Eight fungi produced water-soluble metabolites from all or some of the PAHs. The composition of the water-soluble PAH-metabolites from the most effective solubilizer C. elegans was analyzed by an ultraperformance liquid chromatograph interfaced to a quadrupole time-of-flight mass spectrometer. Thirty-eight metabolites were detected. All of 34 identified metabolites were sulfate-conjugated. The mineralization of (14)C-metabolites, produced by C. elegans, was compared to mineralization of the parent (14)C-PAHs in soil slurries. It was hypothesized that the increased bioavailability and metabolic activation of the metabolites would increase mineralization in soil slurries compared to mineralization of the parent PAHs. Unexpectedly, the mineralization of the (14)C-metabolites was in all cases extremely slow compared to the mineralization of the parent (14)C-PAHs. Slow (14)C-metabolite mineralization was not caused by metabolite toxicity, neither was cometabolic mineralization of (14)C-metabolites stimulated by the presence of active PAH-degraders. High water solubility, low lipophilicity, and extremely slow mineralization of the metabolites indicate a potential problem of leaching of fungal PAH-metabolites to the groundwater. PMID:20136075

Schmidt, Stine N; Christensen, Jan H; Johnsen, Anders R

2010-03-01

234

ARIZONA BORDER STUDY--PAH IN REPLICATES ANALYTICAL RESULTS  

EPA Science Inventory

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

235

Polycyclic aromatic hydrocarbons (PAHs) in livers of California sea otters.  

PubMed

Concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) were measured in livers of 81 adult female sea otters collected along the California coast in 1992-2002. Concentrations of summation operatorPAHs in livers of sea otters were in the range of 588-17400ng/g lipid wt (mean: 3880ng/g, lipid wt). On a wet weight basis, the concentrations ranged from 17 to 1430ng/g (mean: 146ng/g). Overall, di- and tri-cyclic aromatic hydrocarbons, namely, naphthalene, fluorene, phenanthrene/anthracene, and acenaphthylene, were the predominant compounds found in the livers. Although petroleum-related sources appear to be the major contributors to PAH exposure in sea otters, exposure sources varied by geographical sub-regions. Dibenz[a,h]anthracene was found to comprise a significant proportion of the summation operatorPAH concentrations in sea otters from the northern sub-region of the study area. No significant difference existed in the concentrations of summation operatorPAHs among sea otters that died from infectious diseases, emaciation, and noninfectious causes. Concentrations of summation operatorPAHs in livers of sea otters decreased significantly from 1992 to 2002. Because of the rapid metabolism of PAHs in marine mammals such as sea otters, further studies examining the association of PAHs with health effects should determine hydroxylated metabolites in livers. PMID:18177687

Kannan, Kurunthachalam; Perrotta, Emily

2008-03-01

236

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

237

Comparative Developmental Toxicity of Environmentally Relevant Oxygenated PAHs  

SciTech Connect

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

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

2013-09-01

238

On the Viability of the PAH Model as an Explanation of the Unidentified Infrared Emission Features  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbon (PAH) molecules are widely considered the preferred candidate for the carrier of the unidentified infrared emission bands observed in the interstellar medium and circumstellar envelopes. In this paper, we report the results of fitting a variety of non-PAH spectra (silicates, hydrogenated amorphous carbon, coal, and even artificial spectra) using the theoretical infrared spectra of PAHs from the NASA Ames PAH IR Spectroscopic Database. We show that these non-PAH spectra can be well fitted by PAH mixtures. This suggests that a general match between astronomical spectra and those of PAH mixtures does not necessarily provide definitive support for the PAH hypothesis.

Zhang, Yong; Kwok, Sun

2015-01-01

239

Mutagenicity and DNA adduct formation of PAH, nitro-PAH, and oxy-PAH fractions of atmospheric particulate matter from São Paulo, Brazil.  

PubMed

Urban particulate matter (UPM) contributes to lung cancer incidence. Here, we have studied the mutagenic activity and DNA adduct-forming ability of fractionated UPM extractable organic matter (EOM). UPM was collected with a high-volume sampler in June 2004 at two sites, one at street level adjacent to a roadway and the other inside a park within the urban area of the city of São Paulo, Brazil. UPM was extracted using dichloromethane, and the resulting EOM was separated by HPLC to obtain PAH, nitro-PAH, and oxy-PAH fractions which were tested for mutagenicity with the Salmonella strains TA98 and YG1041 with and without S9 metabolic activation. The PAH fraction from both sites showed negligible mutagenic activity in both strains. The highest mutagenic activity was found for the nitro-PAH fraction using YG1041 without metabolic activation; however, results were comparable for both sites. The nitro-PAH and oxy-PAH fractions were incubated with calf thymus DNA under reductive conditions appropriate for the activation of nitro aromatic compounds, then DNA adduct patterns and levels were determined with thin-layer chromatography (TLC) 32P-postlabeling method using two enrichment procedures-nuclease P1 digestion and butanol extraction. Reductively activated fractions from both sites produced diagonal radioactive zones (DRZ) of putative aromatic DNA adducts on thin layer plates with both enrichment procedures. No such DRZ were observed in control experiments using fractions from unexposed filters or from incubations without activating system. Total adduct levels produced by the nitro-PAH fractions were similar for both sites ranging from 30 to 45 adducts per 10(8) normal nucleotides. In contrast, the DNA binding of reductively activated oxy-PAH fractions was three times higher and the adduct pattern consisted of multiple discrete spots along the diagonal line on the thin layer plates. However, DNA adduct levels were not significantly different between the sampling sites. Both samples presented the same levels of mutagenic activity. The response in the Salmonella assay was typical of nitroaromatics. Although, more mutagenic activity was related to the nitro-PAH fraction in the Salmonella assay, the oxy-PAH fractions showed the highest DNA adduct levels. More studies are needed to elucidate the nature of the genotoxicants occurring in São Paulo atmospheric samples. PMID:18294902

Umbuzeiro, Gisela A; Franco, Alexandre; Martins, Maria Helena; Kummrow, Fábio; Carvalho, Lilian; Schmeiser, Heinz H; Leykauf, Jutta; Stiborova, Marie; Claxton, Larry D

2008-03-29

240

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, other than methane, that are capable of producing photochemical oxidants by reactions with nitrogen

Zevenhoven, Ron

241

Polycyclic aromatic hydrocarbon (PAH) and oxygenated PAH (OPAH) air-water exchange during the deepwater horizon oil spill.  

PubMed

Passive sampling devices were used to measure air vapor and water dissolved phase concentrations of 33 polycyclic aromatic hydrocarbons (PAHs) and 22 oxygenated PAHs (OPAHs) at four Gulf of Mexico coastal sites prior to, during, and after shoreline oiling from the Deepwater Horizon oil spill (DWH). Measurements were taken at each site over a 13 month period, and flux across the water-air boundary was determined. This is the first report of vapor phase and flux of both PAHs and OPAHs during the DWH. Vapor phase sum PAH and OPAH concentrations ranged between 1 and 24 ng/m(3) and 0.3 and 27 ng/m(3), respectively. PAH and OPAH concentrations in air exhibited different spatial and temporal trends than in water, and air-water flux of 13 individual PAHs were strongly associated with the DWH incident. The largest PAH volatilizations occurred at the sites in Alabama and Mississippi in the summer, each nominally 10,000 ng/m(2)/day. Acenaphthene was the PAH with the highest observed volatilization rate of 6800 ng/m(2)/day in September 2010. This work represents additional evidence of the DWH incident contributing to air contamination, and provides one of the first quantitative air-water chemical flux determinations with passive sampling technology. PMID:25412353

Tidwell, Lane G; Allan, Sarah E; O'Connell, Steven G; Hobbie, Kevin A; Smith, Brian W; Anderson, Kim A

2015-01-01

242

Process diagnostics  

SciTech Connect

The book contains papers in the areas of combustion and fusion designed to overview major diagnostic techniques (laser-induced fluorescence, spontaneous Raman spectroscopy, interferometry, imaging, Langmuir probes, multiphoton exitation/detection techniques, etc.) as applied to combustion and fusion processes. The materials processing diagnostic papers represent the current state-of-the-art diagnostics in such areas as plasma etching, CVD, PACVD, welding, vacuum arc remelting, metal extrusion, and plasma spraying.

Hays, A.K. (Sandia National Labs., Albuquerque, NM (USA)); Eckbreth, A.C. (United Technologies Corp., East Hartford, CT (USA). Research Center (USA)); Campbell, G.A. (Plasma Materials Technologies, Burbank, CA (USA))

1988-01-01

243

Distribution of polycyclic aromatic hydrocarbons (PAHS) and phenolic endocrine disrupting chemicals in South and Southeast Asian mussels.  

PubMed

A comprehensive monitoring survey for polycyclic aromatic hydrocarbons (PAHs) and phenolic endocrine disrupting chemicals (EDCs) utilizing mussels as sentinel organisms was conducted in South and Southeast Asia as a part of the Asian Mussel Watch project. Green mussel (Perna viridis) samples collected from a total of 48 locations in India, Indonesia, Singapore, Malaysia, Thailand, Cambodia, Vietnam, and the Philippines during 1994-1999 were analyzed for PAHs, EDCs including nonylphenol (NP), octylphenol (OP) and bisphenol A (BPA), and linear alkylbenzenes (LABs) as molecular markers for sewage. Concentrations of NP ranged from 18 to 643 ng/g-dry tissue. The highest levels of NP in Malaysia, Singapore, the Philippines, and Indonesia were comparable to those observed in Tokyo Bay. Elevated concentrations of EDCs were not observed in Vietnam and Cambodia, probably due to the lower extent of industrialization in these regions. No consistent relationship between concentrations of phenolic EDCs and LABs were found, suggesting that sewage is not a major source of EDCs. Concentrations of PAHs ranged from 11 to 1,133 ng/g-dry, which were categorized as "low to moderate" levels of pollution. The ratio of methylphenanthrenes to phenanthrene (MP/P ratio) was >1.0 in 20 out of 25 locations, indicating extensive input of petrogenic PAHs. This study provides a bench-mark for data on the distribution of anthropogenic contaminants in this region, which is essential in evaluating temporal and spatial variation and effect of future regulatory measures. PMID:17370135

Isobe, Tomohiko; Takada, Hideshige; Kanai, Miki; Tsutsumi, Shinobu; Isobe, Kei O; Boonyatumanond, Ruchaya; Zakaria, Mohamad Pauzi

2007-12-01

244

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

PubMed

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

Haritash, A K; Kaushik, C P

2009-09-30

245

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

246

Metabolites of polycyclic aromatic hydrocarbons (PAHs) in bile as biomarkers of pollution in European eel (Anguilla anguilla) from German rivers.  

PubMed

In the light of the alarming decline of the European eel (Anguilla anguilla L.) population, there is an urgent need to define ecological indicators for eel habitat quality. Due to an increasing shortage of glass eels available for local stock enhancement, the decision of whether restocking is a valuable management tool to increase high-quality silver eel escapement to the sea needs to be evaluated. Organic contaminants, such as polycyclic aromatic hydrocarbons (PAHs), are among the major threats to fish in their habitat. Therefore, the aim of the investigation presented here was to examine metabolites of PAHs in eel bile as one possible marker for habitat quality. In total, 170 yellow eels were collected in the rivers Rhine, Ems, Weser, Elbe, Havel, Schlei, Eider, Trave, Warnow, Peene, Uecker, and Oder in 2009. PAH metabolites in eel bile were analyzed using high-performance liquid chromatography with fluorescence detection. Metabolites of pyrene and phenanthrene were investigated. Concentrations of PAH metabolites in eel bile varied significantly between several rivers, with the highest mean concentrations of 1-hydroxypyrene and 1-hydroxyphenanthrene in eel bile from the river Trave (2421 and 632 ng/ml). Moreover, huge differences in the ratio of 1-hydroxypyrene to 1-hydroxyphenanthrene, with the highest mean value in eel bile from the river Ems (7.43) and the lowest mean value in eel bile from the river Uecker (0.70), indicate different sources of PAH contamination. A comparative analysis of PAH-metabolite contamination of eels in different river systems is seen as a first step toward a classification of freshwater habitats for restocking purposes. PMID:21706228

Nagel, F; Kammann, U; Wagner, C; Hanel, R

2012-02-01

247

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

NASA Astrophysics Data System (ADS)

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

Simon, A.; Joblin, C.

2010-03-01

248

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

249

Sorption and chemical transformation of PAHs on coal fly ash  

SciTech Connect

The objective of this research is to characterize the interactions of coal fly ash with polycyclic aromatic hydrocarbons (PAHs) and their derivatives, and to understand the influence of the surface properties of coal ash (and other atmospheric particles) on the chemical transformations of polycyclic aromatic compounds. During the past year the following specific aspects of this broad problem area have been investigated: (a) Fractionation of heterogeneous coal fly ash samples into different particle types varying in size and chemical composition (carbonaceous, mineral-magnetic, and mineral nonmagnetic); (b) The use of gas-solid chromatography to measure heats of sorption of PAHS, and PAH derivatives, on coal fly ashes and ash fractions. (c) Identification of the major photoproduct(s) of the photodecomposition of one PAH (benz[a]anthracene) sorbed on model adsorbents; (d) Estimation of fractal dimensions'' of coal fly ash particles by use of specific surface area measurements, with an ultimate objective of using these measurements to assess the importance of inner-filter effects'' on the photodecomposition of PAHs sorbed on fly ash particles. (e) The photochemical transformation of a representative nitro-PAH derivative (1-nitropyrene) sorbed on fly ash. (f) Development of techniques for studying the nonphotochemical reactions of hydroxyl radicals (and other atmospheric constituents) with PAHs sorbed on fly ash. Progress achieved, and problems encountered, in each of these major areas of emphasis is described below.

Mamantov, G.; Wehry, E.L.

1992-01-01

250

PAHs in sediments: Unmixing and CMB modeling of sources  

SciTech Connect

A chemical mass balance (CMB) model, applied to polycyclic aromatic hydrocarbon (PAH) compounds, is used to apportion PAH sources in a group of seven sediment cores in the Milwaukee Basin of the central Lake Michigan area. PAH apportionment results indicate the dominance of coke oven emissions from 1925--1976, and of highway inputs from 1983--1992 for most of the seven cores. This is consistent with results of carbon particle analysis from the same basin. Milwaukee and Port Washington appear to be primary contributors of point source inputs of PAHs from coke ovens and highway dust. Wood burning is a minor source ({lt}13%). These findings are supported by an independent factor analysis study. Historical PAH records are also determined for the seven sediment cores. The records are unmixed and averaged over the basin. The resulting average record is then used as measured profile in a CMB model to determine PAH sources. Source profiles are historical records of the consumption of coal, petroleum, and wood, including coal used for coke production. A cubic spline technique is developed and applied for the curve fitting of original data points for all of the cores. Unmixed profiles reveal a number of features that are not seen in the original data. Wood burning, coke oven emissions, and highway dust profiles are found to resemble the national consumption records. Coal burning is a very small PAH source ({lt}1%).

Christensen, E.R.; Rachdawong, P.; Karls, J.F.; Van Camp, R.P.

1999-11-01

251

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

252

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

253

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

254

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

SciTech Connect

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

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

1985-02-01

255

Occurrence and fate of organochlorinated pesticides and PAH in agricultural soils from the Ebro River basin.  

PubMed

This study was aimed to assess the presence and fate of 22 organochlorinated pesticides (OCHs) and their degradation products and 16 Environmental Protection Agency-priority polycyclic aromatic hydrocarbons (PAHs) in soils of the Ebro River basin (NE Spain) during a 3-year period. The study site is characterized by a long and active agricultural history where pesticides have largely been used. Soils were extracted using pressurized liquid extraction followed by gas chromatography-mass spectrometry. This procedure was optimized in terms of multiresidue analysis and effective cleanup and proved to have excellent analytical performance (recoveries ranging between 71% and 133%, standard deviation <14%, and a method detection limit from 0.19 to 7.38 microg/kg). Soils form the Ebro basin showed a prevalence of 4,4'-DDT and 4,4'-DDE, found in 53% and 88% of the soil samples between 0.13 and 58.17 microg/kg-dw (dry weight), respectively, indicating a slight decreasing trend of DDT within time. PAHs were detected in all soil samples at concentrations up to 465 microg/kg-dw, and the phenanthrene/anthracene (<10) and fluoranthene/pyrene (>1) ratios indicated combustion processes as the main source attributing to the burning of weeds and vegetable wastes after harvesting. No traces of any of the OCHs and PAHs were detected in groundwater, indicating that leaching for agricultural fields is not an important process of transport for these compounds. Overall, we propose the need to perform a monitoring program to evaluate the temporal tendencies and potential impact of pesticides and PAH in soils. PMID:19052798

Hildebrandt, Alain; Lacorte, Sílvia; Barceló, Damià

2009-08-01

256

Modeling the PAH Emission Spectra of Protoplanetary and Debris Disks  

NASA Astrophysics Data System (ADS)

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

Li, Aigen; Lunine, J. I.

2006-05-01

257

Behavior of PAH/mineral associations during thermodesorption: impact for the determination of mineral retention properties towards PAHs.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) associated with two minerals (silica sand and bentonite) presenting opposite retention properties were analyzed with a thermodesorption (Td)-GC-MS coupling in order to validate this technique as a new and rapid way to evaluate the solid sorption properties. Two analysis modes were used, evolved gas analysis (EGA) and Td with cryo-trap. EGA allowed a real-time monitoring of the compounds desorbed during a temperature program and gave a first screening of the samples while Td gave more precise indications on compound abundances for selected temperature ranges. When associated with silica sand, PAHs were released at relatively low temperatures (<300 °C) close to corresponding boiling point, whereas for the PAH/bentonite mixture, PAHs were desorbed at much higher temperatures; they were also present in much lower abundance and were associated with mono-aromatic compounds. With bentonite, the PAH abundances decreased and the mono-aromatics increased with the increasing PAH molecular weight. These results indicated a clear PAH retention by the bentonite due to polymerization, followed by a thermal cracking at higher temperatures. The Td-GC-MS was proven to efficiently underline differences in retention properties of two minerals, and this study highlights the great potential of this technique to evaluate compound/matrix bond strength and interaction. PMID:25772555

Biache, Coralie; Lorgeoux, Catherine; Saada, Alain; Faure, Pierre

2015-05-01

258

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

259

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

260

Assessing PAH exposure in feral finfish from the Northwest Atlantic.  

PubMed

Polycyclic aromatic hydrocarbon (PAH) concentrations were examined in small finfish (<30 cm) represented by capelin, sand lance, American plaice, yellowtail flounder and herring collected opportunistically in various NAFO divisions. Analyses were performed on whole fish and in a portion of the samples; concentrations in internal organs were compared to the rest of the carcass. The effect of pool size, size differences within and between species, lipid content and location were examined to interpret PAH concentrations. Measurements were carried out before the development of the Hibernia oil fields and represent baseline levels for future comparison. Limits in assessing future risk that could be due to discharges of produced water or accidental oil spills are also discussed. Increasing knowledge on the bioaccumulation of PAH, on the production of bile metabolites, the formation of DNA-adducts and of the potential toxic effects associated with PAH will lead to better ecosystem management and protection for future generations. PMID:16364371

Hellou, J; Leonard, J; Collier, T K; Ariese, F

2006-04-01

261

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...

262

PAH formation in carbon-rich circumstellar envelopes  

NASA Technical Reports Server (NTRS)

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

Feigelson, Eric D.; Frenklach, Michael

1989-01-01

263

Biodegradability of select polycyclic aromatic hydrocarbon (pah) mixtures  

E-print Network

Polycyclic aromatic hydrocarbons (PAHs) are environmentally significant because of their ubiquity and the toxicity of some. Their recalcitrance and persistence makes them problematic environmental contaminants. Microbial degradation is considered...

Desai, Anuradha M.

2007-04-25

264

Effects of PAHs on the feeding activity of tubificid worms  

SciTech Connect

Sediment collected from a clean site in LA was sieved through a 125{mu}m screen and contaminated with individual PAHs (pyrene, phenanthrene and dibenzofuran) at increasing concentrations using spiking procedure and with a mixture of the 3 PAHs at a single concentration by shell coating. Feeding activity was estimated by defecation rate. Groups of 15 worms were assigned to defecation chambers in 4 replicates per treatment. Feces were collected daily for 10 days, filtered through a 8{mu}m membrane filter and dry weight measured. Results obtained with phenanthrene and mixture of 3 PAHs indicate that PHA bulk concentration of 100 mg/dry kg and higher significantly reduce tubificid ingestion of sediment. Total recovery to control levels occurred when worms exposed to high concentration of PAH were transferred to clean sediment. Total OC was determined to be 3.2 %.

Lotufo, G.R. [Louisiana State Univ., Baton Rouge, LA (United States)

1994-12-31

265

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.

266

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

267

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

268

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

269

Fish embryos are damaged by dissolved PAHs, not oil particles.  

PubMed

To distinguish the toxicity of whole oil droplets from compounds dissolved in water, responses of zebrafish embryos exposed to particulate-laden, mechanically dispersed Alaska North Slope crude oil (mechanically dispersed oil (MDO)) were compared to those of embryos protected from direct oil droplet contact by an agarose matrix. Most polycyclic aromatic hydrocarbons (PAHs) in MDO were contained in oil droplets; about 16% were dissolved. The agarose precluded embryo contact with particulate oil but allowed diffusive passage of dissolved PAHs. The incidence of edema, hemorrhaging, and cardiac abnormalities in embryos was dose-dependent in both MDO and agarose and the biological effects in these compartments were identical in character. Although mean total PAH (TPAH) concentrations in MDO were about 5-9 times greater than in agarose, dissolved PAH concentrations were similar in the two compartments. Furthermore, mean differences in paired embryo responses between compartments were relatively small (14-23%, grand mean 17%), typically with a larger response in embryos exposed to MDO. Therefore, the embryos reacted only to dissolved PAHs and the response difference between compartments is explained by diffusion. Averaged over 48 h, the estimated mean TPAH concentration in agarose was about 16% less than the dissolved TPAH concentration in MDO. Thus, PAHs dissolved from oil are toxic and physical contact with oil droplets is not necessary for embryotoxicity. PMID:18479765

Carls, Mark G; Holland, Larry; Larsen, Marie; Collier, Tracy K; Scholz, Nathaniel L; Incardona, John P

2008-06-23

270

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

271

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

272

Laboratory retention of vapor-phase PAHs using XAD adsorbents  

NASA Astrophysics Data System (ADS)

This investigation focuses on the retention of polycyclic aromatic hydrocarbons (PAHs) on XAD (-2, -4, and -16) resins, which is crucial for estimating PAH gas/particle partition coefficients. The XAD resins were found to exhibit higher specific retention volumes ( Vg, net gas-phase retention volume per unit weight (gram) of sorbent) than PUF for some 3-ring PAHs at 20 oC. The 3-ring compounds broke through the XAD adsorbents more easily than the 4-ring compounds at constant temperature. For the equation, Log Vg= m log PL+ b ( PL: subcooled liquid vapor pressure) the average m values were approximately -0.2 and -0.3 at 20 and 40 oC, respectively. Moreover, the Vg values were lower at 40 oC than at 20 oC for each PAH compound. The XAD-4 appeared to have a greater Vg value (adsorbent weight based) for each compound among the adsorbents at 40 oC. It was possible that PAH micropore adsorption dominated on XAD-4, different from the predominance of the PAH surface adsorption on the other two adsorbents.

Lee, James J.; Huang, Kuo-Lin; Yu, Yaochien Y.; Chen, Minsung S.

273

Do Small, Neutral PAHs Survive in the ISM?  

NASA Astrophysics Data System (ADS)

Polycyclic aromatic hydrocarbon (PAH) molecules are ubiqutous in the universe. They reveal themselves primarily through emission features in the near- and mid-IR, commonly referred to as aromatic emission features (AEF) or the unidentified infrared (UIR) bands. We discovered the presence of small 3-4 ringed, neutral PAHs in the Red Rectangle (RR) through their blue fluorescence (Vijh et al. 2004; Vijh et al. 2005). The central star in the RR is in an active dust producing stage and these small PAHs are just being formed in the gas. Do these small PAHs survive under harsh interstellar conditions? Are the AEFs primarily due to larger PAHs? To answer these questions we have obtained long slit spectra of different reflection nebulae and star forming regions, where the temperatures of the illuminating stars cover a range from ˜ 9000 - 25000 K. We will present results that establish the presence or absence of blue fluorescence from small, neutral PAHs as a function of the local radiation field density. This research is funded by the NSF grant AST 0307307 to the University of Toledo. \\textbf{References} Vijh, U.P., Witt, A. N., & Gordon, K. D. 2004, ApJ, 606, L68 Vijh, U.P., Witt, A. N., & Gordon, K. D. 2005, ApJ (in press)

Vijh, U. P.; Witt, A. N.; Gordon, K. D.

2004-12-01

274

PAH in fossil fuels and their geochemical significance  

NASA Astrophysics Data System (ADS)

With the help of the advanced TSQ-45 model GC-MS-MS with INCOS data system, polycyclic aromatic hydrocarbons (PAH) of 85 samples from twelve sedimentary basins both in China and abroad, including crude oils, source rocks, oil shales and coals, have been studied. PAH, source features, sedimentary environments and maturity of organic matter have been discussed. Three series, i.e. fluorene series, dibenzofuran series and dibenzothiophene series, may be derived from the same original materials, and their properties of internal compositions may be mainly controlled by oxi-reduction conditions. The major changes of PAH are cracking, dealkylation and structural rearrangement during the maturation of organic matter, therefore the changes in ring number of PAH, the internal composition of the same series of compounds and methylphenanthrene index may reflect the maturity of organic matter. On the basis of our analysis and study, a new maturity parameter, i.e. the stable three-fluorene series index, has been proposed. Biphenyl series compounds may be the products of high-temperature cracking. PAH can be used in oil-source correlation studies. The fingerprint of PAH is particularly important for those crude oils or source rocks which are high-mature or in which steroids and terpenoids have been severely altered because of biodegradation.

Lin Renzi; Wang Peirong

275

Diagnostic radiology  

SciTech Connect

Developments in the burgeoning field of diagnostic radiology have continued apace. Four areas that represent either subspecialities or technological advances in diagnostic radiology will be considered in this report: ultrasonography, interventional radiology, nuclear radiology, and magnetic resonance. In no sense is the exclusion of other subdisciplines and modalities (eg, pediatric radiology, computed tomography) and indication of their of importance or their failure to include innovative concepts.

Leeds, N.E.; Jacobson, H.G.

1986-10-17

276

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, ...

277

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

278

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

279

Relationship Between Polycyclic Aromatic Hydrocarbon (PAH) Accumulation in Semipermeable Membrane Devices and PAH Bile Metabolite Levels in Atlantic Cod (Gadus morhua)  

Microsoft Academic Search

The extent to which accumulations of polycyclic aromatic hydrocarbons (PAH) by semipermeable membrane devices (SPMD) may be correlated to the concentration of PAH metabolites in fish was examined. Atlantic cod (Gadus morhua) and SPMD were exposed over a 4-wk period to a mixture that was designed to simulate the composition of PAH in produced water discharges in the North Sea.

Christopher Harman; Tor Fredrik Holth; Ketil Hylland; Kevin Thomas; Merete Grung

2009-01-01

280

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

281

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

282

Molecular actions of polyhalogenated arylhydrocarbons (PAHs) in female reproduction.  

PubMed

Polyhalogenated aromatic arylhydrocarbons (PAHs) such as polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), the polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are persistent lipophilic pollutants, which affect female fertility resulting in severe reproductive dysregulation, including anovulation, reduced conception rates, abortion, menstrual abnormalities and developmental defects of female reproductive tissues. Many PAHs exert their effects by activating a family of basic helix-loop-helix (bHLH) transcription factors, the arylhydrocarbon receptor (AhR) and the arylhydrocarbon receptor nuclear translocator (ARNT), which result in the expression of AhR target molecules. Complex interactions between PAH-mediated AhR activation and ER signalling pathways have been discovered which may contribute to the developmental malformations, impact on reproductive dysfunctions and promote carcinogenic dedifferentiation of tissues within the female reproductive tract. This review will focus on the multifaceted roles of PAHs in key organs of the female reproductive tract, the ovary, uterus/ endometrium and the mammary gland. The complexity and diversity of actions unleashed by PAHs in these female reproductive tissues identify these environmental pollutants as important endocrine disrupting toxicants impacting on female fertility. PMID:15777215

Hombach-Klonisch, S; Pocar, P; Kietz, S; Klonisch, T

2005-01-01

283

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

284

Predicting low biota to sediment accumulation factors of PAHs by using infinite-sink and equilibrium extraction methods as well as BC-inclusive modeling.  

PubMed

Sequestration of polycyclic aromatic hydrocarbons (PAHs) results in the slow release of PAHs from sediment to the aqueous environment, thus limiting bioavailability. Three methods to account for the limited bioavailability of native PAHs to the gastropod Hinia reticulata were therefore investigated: (i) infinite-sink extractions that measure desorption; (ii) equilibrium extractions that measure freely dissolved pore water concentrations and (iii) black carbon-inclusive modeling. The rapidly desorbing fraction was estimated based on the amount desorbed by Tenax. Relatively small amounts of PAHs (<9%) were present in F(rapid) and the observed solid-water distribution ratios (K(d,obs)) were approximately 1-2 orders of magnitude higher than literature K(oc) values. Biota to sediment accumulation factors (BSAFs) measured in the gastropod H. reticulata ranged from 0.02 to 0.07, 10-140 times lower than the theoretical value of approximately 1-2. The BSAFs calculated using the rapidly desorbing fraction or freely dissolved aqueous concentrations were also much lower than the theoretical value, and median values differed from the measured BSAFs by only a factor of 1.5-9. Furthermore, the result of using a BC-inclusive BSAF model could explain the deviation from the theoretical BSAF value and account for the low bioavailability of these native PAHs to H. reticulata. Risk assessment strategies of in situ contamination should therefore include a combination of chemical methods accounting for bioavailability, as well as bioaccumulation studies. PMID:16434080

Oen, Amy M P; Schaanning, Morten; Ruus, Anders; Cornelissen, Gerard; Källqvist, Torsten; Breedveld, Gijs D

2006-08-01

285

Polycyclic aromatic hydrocarbons (PAHs) in transplanted Manila clams (Tapes philippinarum) from the Lagoon of Venice as assessed by PAHs/shell weight index: a preliminary study.  

PubMed

Variation of polycyclic aromatic hydrocarbons (PAHs) levels was assessed in Tapes philippinarum from the Lagoon of Venice. Clams were transplanted from a polluted area next to Porto Marghera to two rearing areas of the Southern Lagoon. Analyses of PAHs were made in sediments and clams by GC/MS at first sampling and after 30, 60 and 180 days. Principal component analysis was performed to elucidate bioaccumulation and depuration pattern and input sources. Biota-Sediment-Accumulation-Factor (BSAF) was applied to evaluate the PAHs input sources from sediment. Condition index was calculated to compare the seasonal variation of clam tissue to PAHs levels. To propose results not affected by seasonal changes in flesh weight of clams, the approach based on the calculation of PAHs/SW index was applied. From the results, it was concluded that PAHs/SW index is more recommendable to asses temporal variation of PAHs levels in Manila clams. PMID:18001805

Boscolo, Rossella; Cacciatore, Federica; Giovanardi, Otello

2007-01-01

286

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

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

287

[Health risk assessment of coke oven PAHs emissions].  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) produced by coke oven are with strong toxicity and carcinogenicity. Taken typical coke oven of iron and steel enterprises as the case study, the dispersion and migration of 13 kinds of PAHs emitted from coke oven were analyzed using AERMOD dispersion model, the carcinogenic and non-carcinogenic risks at the receptors within the modeling domain were evaluated using BREEZE Risk Analyst and the Human Health Risk Assessment Protocol for Hazardous Waste Combustion (HHRAP) was followed, the health risks caused by PAHs emission from coke oven were quantitatively evaluated. The results indicated that attention should be paid to the non-carcinogenic risk of naphthalene emission (the maximum value was 0.97). The carcinogenic risks of each single pollutant were all below 1.0E-06, while the maximum value of total carcinogenic risk was 2.65E-06, which may have some influence on the health of local residents. PMID:25244863

Bo, Xin; Wang, Gang; Wen, Rou; Zhao, Chun-Li; Wu, Tie; Li, Shi-Bei

2014-07-01

288

Sediment-porewater partitioning of polynuclear aromatic hydrocarbons (PAHs)  

SciTech Connect

Quantifying the distribution of hydrophobic organic compounds between contaminated sediment and interstitial water is key to understanding their fate and effects in aquatic ecosystems. Sampling during the wet and dry-seasons in San Francisco Bay has revealed that the extent of partitioning, measured as the apparent sediment organic carbon-porewater distribution coefficient (K{sub oc}{prime}), was positively correlated with the octanol-water distribution coefficient (K{sub ow}) for a suite of pyrogenically-derived, 2-6 ring PAHs. In addition, sediment PAHs (organic carbon basis) were associated with the silt fraction and organic carbon content. Moreover, K{sub oc}{prime} decreased along an intertidal gradient and was an order of magnitude higher during the wet season when runoff into the Bay was high. Our results provide evidence that substrate heterogeneity, a factor not accounted for in simple equilibrium models, can significantly alter the distribution of PAHs in this environment.

Maruya, K.A.; Risebrough, R.W.; Horne, A.J. [Univ. of California, Berkeley, CA (United States)

1996-10-01

289

Search for fullerenes and PAHs in the diffuse interstellar medium  

NASA Astrophysics Data System (ADS)

Recent studies suggest carbon-containing molecules as the best candidates for carriers of the unidentified diffuse interstellar bands (DIBs). considering their abundance and ability to form stable bonds in interstellar space. We have searched for new DIBs in the near-IR and have detected two new diffuse bands that are consistent with laboratory measurements of C 60+ in a neon matrix. Criteria for this possible identification are discussed. From these observations and the DIB treasured absorption. we estimate that up to 0.9% of interstellar carbon could be in the form of C 60+ We also searched for poly cyclic aromatic hydrocarbon (PAH) canons and have derived corresponding limits for the presence of the coronene C 24H 12 and ovalene C 32H 14 cations in space. We have studied the ionization properties of these PAH cations, which could explain their selective destruction. From these results we discuss the role of fullerenes and PAHs as possible DIB carriers.

Ehrenfreund, P.; Foing, B. H.

1995-02-01

290

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

NASA Astrophysics Data System (ADS)

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

Crimmins, Bernard S.; Baker, Joel E.

291

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

292

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

293

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

294

Experimental study on the removal of PAHs using in-duct activated carbon injection.  

PubMed

This paper presents the incineration tests of municipal solid waste (MSW) in a fluidized bed and the adsorption of activated carbon (AC) on polycyclic aromatic hydrocarbons (PAHs). An extraction and high performance liquid chromatography (HPLC) technique was used to analyze the concentrations of the 16 US EPA specified PAHs contained in raw MSW, flue gas, fly ash, and bottom ash. The aim of this work was to decide the influence of AC on the distribution of PAHs during the incineration of MSW. Experimental researches show that there were a few PAHs in MSW and bottom ash. With the increase of AC feeding rate, the concentrations of three- to six-ring PAHs in fly ash increased, and the concentration of two-ring PAH decreased. The total-PAHs in flue gas were dominated by three-, and four-ring PAHs, but a few two-, five-ring PAHs and no six-ring PAHs were found. PAHs could be removed effectively from flue gas by using in-duct AC injection and the removal efficiencies of PAHs were about 76-91%. In addition, the total toxic equivalent (TEQ) concentrations of PAH in raw MSW, bottom ash, fly ash, and flue gas were 1.24 mg TEQ kg-1, 0.25 mg TEQ kg-1, 6.89-9.67 mg TEQ kg-1, and 0.36-1.50 microg TEQ Nm-3, respectively. PMID:15811415

Zhou, Hong-Cang; Zhong, Zhao-Ping; Jin, Bao-Sheng; Huang, Ya-Ji; Xiao, Rui

2005-05-01

295

Radius Ratio  

NSDL National Science Digital Library

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

296

Biodegradation of PAHs and PCBs in soils and sludges  

USGS Publications Warehouse

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

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

2007-01-01

297

Coronal diagnostics.  

NASA Technical Reports Server (NTRS)

This is an introduction to this part of the proceedings and an overview of coronal diagnostics. The current understanding of coronal loops is summarized. Included are observations from ground-based radio telescopes and from X ray telescopes lofted above the atmosphere, as well as theoretical interpretations of these observations. Also included in these introductory remarks is a discussion of the three dimensional structure of coronal loops. Alternative radiation mechanisms are then described within the context of both the radio and X ray emission. Various methods of determining the strength and structure of the coronal magnetic field are then described, followed by the coronae of nearby stars and future prospects for radio diagnostic of coronal loops.

Lang, Kenneth R.

1986-01-01

298

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

EPA Science Inventory

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

299

Long-Term Composition Dynamics of PAH-Containing NAPLs and  

E-print Network

08544 Subsurface contaminants such as coal tar, creosote, diesel fuel, and other petroleum) containing polycyclic aromatic hydrocarbons (PAHs). A model is presented describing the interdependence hydrocarbon (TPH). Introduction Polycyclic aromatic hydrocarbons (PAHs) represent an important class

Peters, Catherine A.

300

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

301

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

302

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...

303

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...

304

75 FR 8937 - Development of a Relative Potency Factor (RPF) Approach for Polycyclic Aromatic Hydrocarbon (PAH...  

Federal Register 2010, 2011, 2012, 2013, 2014

...RPF) Approach for Polycyclic Aromatic Hydrocarbon (PAH) Mixtures'' (EPA/635/R-08...RPF) Approach for Polycyclic Aromatic Hydrocarbon (PAH) Mixtures'' is available primarily...consider your comment. Instructions: Direct your comments to Docket ID No....

2010-02-26

305

Identification of carbonaceous geosorbents for PAHs by organic petrography in river floodplain soils.  

PubMed

Organic petrographic analysis was applied to provide direct information on carbonaceous geosorbents for PAHs in river floodplain soils. The anthropogenic OM group (primarily coal and coal-derived particles) displayed large volume amounts for all the soil samples. Distinct PAH concentrations with similar PAH distribution patterns were determined in grain size and density fractions for each sample. Two-ring PAHs had stronger correlation to organic carbon (OC) than black carbon (BC) contents, while heavier PAHs showed correlation to BC, rather than OC. In this study, we combined grain size and density separation, PAH determinations, TOC and BC measurements, and organic petrographic identification, and concluded that two-ring PAHs in soils were associated to coal particles. Other heavier PAHs could be more controlled by black carbon (BC), which were mostly coal-derived particles from former coal mining and coal industrial activity. PMID:18280535

Yang, Yi; Ligouis, Bertrand; Pies, Carmen; Achten, Christine; Hofmann, Thilo

2008-05-01

306

BIODEGRADATION OF SEDIMENT-BOUND PAHS IN FIELD-CONTAMINATED SEDIMENT  

EPA Science Inventory

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

307

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

308

SYNTHESIS AND BIOLOGICAL ACTIVITY OF NITRO-SUBSTITUTED CYCLOPENTA-FUSED PAH  

EPA Science Inventory

PAH containing a peripherally fused cyclopenta ring are genotoxically active in Salmonella and mammalian cells and have been identified in combustion emissions. Since the cyclopenta ring is predicted to be susceptible to electrophilic attack, nitrosubstituted cyclopenta-fused PAH...

309

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

310

Polycyclic aromatic hydrocarbons (PAHs) in atmospheric dustfall from the industrial corridor in Hubei Province, Central China.  

PubMed

Thirty atmospheric dustfall samples collected from an industrial corridor in Hubei Province, central China, were analyzed for 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) to investigate their concentrations, spatial distributions, sources, and health risks. Total PAH concentrations (?PAHs) ranged from 1.72 to 13.17 µg/g and averaged 4.91 µg/g. High molecular weight (4-5 rings) PAHs averaged 59.67 % of the ?PAHs. Individual PAH concentrations were not significantly correlated with total organic carbon, possibly due to the semi-continuous inputs from anthropogenic sources. Source identification studies suggest that the PAHs were mainly from motor vehicles and biomass/coal combustion. The incremental lifetime cancer risks associated with exposure to PAHs in the dustfall ranged from 10(-4) to 10(-6); these indicate potentially serious carcinogenic risks for exposed populations in the industrial corridor. PMID:25239676

Zhang, Jiaquan; Qu, Chengkai; Qi, Shihua; Cao, Junji; Zhan, Changlin; Xing, Xinli; Xiao, Yulun; Zheng, Jingru; Xiao, Wensheng

2014-09-12

311

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

312

NSTX Diagnostics and Operation: Status and Plans  

SciTech Connect

The low aspect ratio and low magnetic field of the National Spherical Torus Experiment (NSTX) create many challenges for plasma diagnostics and control, as well as opportunities for studying new plasma phenomena. This paper describes the diagnostics now installed for studies of confinement, stability and edge plasma phenomena, and some of the diagnostic developments planned for the near future. The design of the plasma control system and plans for its development are also presented.

M.G. Bell; R.E. Bell; B.P. LeBlanc; S.S. Medley; and the NSTX Research Team

2001-08-30

313

Understanding the Complexity and Strategic Evolution in PAH Remediation Research  

Microsoft Academic Search

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

Biswanath Mahanty; Kannan Pakshirajan; Veeranki Venkata Dasu

2011-01-01

314

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...

315

Efficiency of butyl rubber sorbent to remove the PAH toxicity.  

PubMed

Large amounts of polycyclic aromatic hydrocarbons (PAHs) have been released to the marine environment as a result of oil spills and from other sources including wastewaters, surface runoff, industrial processes, atmospheric deposition, biosynthesis, and natural events such as forest fires. PAHs have been known to affect a variety of biological processes and can be potent cell mutagens/carcinogens and toxic. In this study, PAH toxicity removal was investigated by using a novel macroporous butyl rubber (BR) sorbent. To find out the toxicity removal efficiency of the sorbents, the toxicity tests with Vibrio fisheri (luminescence bacteria) and Phaeodactylum tricornutum (marine algae) were applied to the acenaphthene (Ace) and phenanthrene (Phen) solutions in seawater (Ace: 500- 1000 ?g/L; Phen; 100-1000 ?g/L) before and after sorbent applications. Additionally, lysosomal stability and filtration rate biomarker techniques were applied to the mussels (Mytilus galloprovincialis) exposed to 1000 ?g/L Phen solution and bioaccumulation was measured. The results showed that the toxicity of the PAH solutions decreased 50-100 percent depending on the concentration of the solutions and organisms. Phaeodactylum was found as the most sensitive organism to Phen and Ace. Since the application of BR sorbent removed the Phen from the solution, the bioaccumulated Phen amount in the mussels decreased accordingly. PMID:21714631

Okay, O S; Özdemir, P; Yakan, S D

2011-01-01

316

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

317

Dissipation of PAHs in saturated, dredged sediments: A field trial  

Microsoft Academic Search

Sediments dredged from navigable rivers often contain elevated concentrations of recalcitrant, potentially toxic organic compounds such as polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). The presence of these compounds often requires that the sediments be stored in fully contained disposal facilities. A 3-year field study was conducted at the Jones Island disposal facility in Milwaukee, Wisconsin, to compare bioremediation of

K. E. Smith; A. P. Schwab; M. K. Banks

2008-01-01

318

LAND TREATMENT OF TWO PLATEAU MATERIALS CONTAMINATED WITH PAHS  

EPA Science Inventory

This study was designed to evaluate several treatments for their ability to enhance the biological removal of polycyclic aromatic hydrocarbons (PAHs) from contaminated soil and sediment. Previously land-treated material was used to test the treatments in a 13 week bench scale stu...

319

Human Exposures to PAHs: an Eastern United States Pilot Study  

EPA Science Inventory

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

320

Energy sources of polycyclic aromatic hydrocarbons. [Carcinogenicity of PAHs  

SciTech Connect

Combustion is the predominant end-process by which fossil fuels are converted to energy. Combustion, particularly when inefficient, is also the primary technological source of polycyclic aromatic hydrocarbons (PAHs) released into the environment. The need for liquid fuels to supply the transportation industry and for nonpolluting fuels for heat and power generation provide the incentive to commercialize processes to convert coal to substitute natural gas and oil. These processes represent a potentially massive new source of environmental PAHs. Insuring an adequate supply of energy with minimum impact on the environment and on health is one of the most important, urgent, and challenging goals currently facing science and technology. Polycyclic aromatic hydrocarbon related carcinogenesis is among the most important of possible occupational- and environmental-health impacts of much of the current and projected national energy base. An understanding of the relationship of polycyclic aromatic hydrocarbons (PAHs) to human cancer and a continued surveillance of energy sources for PAH content are necessary to minimize this impact.

Guerin, M. R.

1977-01-01

321

The atmospheric photooxidation of gaseous PAHs on water films  

NASA Astrophysics Data System (ADS)

The processing of organic chemicals such as PAHs in fog can lead to more harmful oxy- and nitro-PAHs. Hence, the photo-transformation of gas phase PAHs (e.g. Naphthalene and phenanthrene) is important to understand in the atmospheric environment. This work summarizes our work on the uptake and UV-photo-oxidation of these gas phase PAHs in thin water films such as occurring in fogs and aerosols. A flow tube reactor was used to carry out these reactions. The rate of photo-oxidation was substantially higher in a thin film as compared to a bulk phase reaction1. Several products were identified in the water films and the mechanism of photo-oxidation was assessed. The presence of a natural surfactant in the water led to multiple effects on the rate of reaction. These were characterized via a dual mechanism of self-sensitized and surfactant-sensitized pathways for reaction. The atmospheric implications of these observations will be explored in this paper.

Valsaraj, K. T.; Chen, J.

2007-05-01

322

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...

323

Pyrogenic molecular markers: linking PAH with BPCA analysis.  

PubMed

Molecular characterization of pyrogenic organic matter (PyOM) is of great interest to understand the formation and behavior of these increasingly abundant materials in the environment. Two molecular marker methods have often been used to characterize and trace PyOM: polycyclic aromatic hydrocarbon (PAH) and benzenepolycarboxylic acid (BPCA) analysis. Since both methods target pyrogenic polycyclic compounds, we investigated the linkages between the two approaches using chars that were produced under controlled conditions. Rye and maize straws and their analogues charred at 300, 400 and 500 °C, respectively, were thus analyzed with both methods. Moreover, we also measured BPCAs directly on the lipid extracts, on which PAHs were analyzed, and on the respective extraction residues, too. Both methods revealed important features of the chars, in particular the increasing degree of aromatic condensation with increasing highest heating temperature (HTT). The overlap between the two methods was identified in the lipid fraction, where the proportion of benzenetricarboxylic acids (B3CAs) correlated with PAH abundance. The results confirmed the validity and complementarity of the two molecular marker methods, which will likely continue to play a crucial role in PyOM research due to the recent developments of compound-specific PAH and BPCA stable carbon (?(13)C) and radiocarbon ((14)C) isotope methods. PMID:25084061

Wiedemeier, Daniel B; Brodowski, Sonja; Wiesenberg, Guido L B

2015-01-01

324

Atmospheric versus biological sources of polycyclic aromatic hydrocarbons (PAHs) in a tropical rain forest environment  

Microsoft Academic Search

To distinguish between pyrogenic and biological sources of PAHs in a tropical rain forest near Manaus, Brazil, we determined the concentrations of 21 PAHs in leaves, bark, twigs, and stem wood of forest trees, dead wood, mineral topsoil, litter layer, air, and Nasutitermes termite nest compartments. Naphthalene (NAPH) was the most abundant PAH with concentrations of 35ngm?3 in air (>85%

Martin Krauss; Wolfgang Wilcke; Christopher Martius; Adelmar G. Bandeira; Marcos V. B. Garcia; Wulf Amelung

2005-01-01

325

ASSESSING THE BIOAVAILABILITY OF PAHS IN FIELD-CONTAMINATED SEDIMENT USING XAD-2 ASSISTED DESORPTION  

EPA Science Inventory

In the bioremediation of soils/sediments contaminated with polycyclic aromatic hydrocarbons (PAHs) it is imperative to determine the fraction of the PAHs that is amenable to remediation. For example, what fraction of the PAHs is available to the indigenous microorganisms, i.e. bi...

326

Polycyclic aromatic hydrocarbons (PAHs) in the water column and sediment core of Deep Bay, South China  

NASA Astrophysics Data System (ADS)

The levels of 15 polycyclic aromatic hydrocarbons (PAHs) were determined in seawater, suspended particulate matter (SPM), surface sediment and core sediment samples of Deep Bay, South China. The average concentrations ? 15PAHs were 69.4 ± 24.7 ng l -1 in seawater, 429.1 ± 231.8 ng g -1 in SPM, and 353.8 ± 128.1 ng g -1 dry weight in surface sediment, respectively. Higher PAH concentrations were observed in SPM than in surface sediment. Temporal trend of PAH concentrations in core sediment generally increased from 1948 to 2004, with higher concentrations in top than in sub-surface, implying a stronger recent input of PAHs owing to the rapid economic development in Shenzhen. Compared with historical data, the PAH levels in surface sediment has increased, and this was further confirmed by the increasing trend of PAHs in the core sediment. Phenanthrene, fluoranthene and pyrene dominated in the PAH composition pattern profiles in the Bay. Compositional pattern analysis suggested that PAHs in the Deep Bay were derived from both pyrogenic and petrogenic sources, and diesel oil leakage, river runoff and air deposition may serve as important pathways for PAHs input to the Bay. Significant positive correlations between partition coefficient in surface sediment to that in water ( KOC) of PAH and their octanol/water partition coefficients ( KOW) were observed, suggesting that KOC of PAHs in sediment/water of Deep Bay may be predicted by the corresponding KOW.

Qiu, Yao-Wen; Zhang, Gan; Liu, Guo-Qing; Guo, Ling-Li; Li, Xiang-Dong; Wai, Onyx

2009-06-01

327

BmPAH Catalyzes the Initial Melanin Biosynthetic Step in Bombyx mori  

PubMed Central

Pigmentation during insect development is a primal adaptive requirement. In the silkworm, melanin is the primary component of larval pigments. The rate limiting substrate in melanin synthesis is tyrosine, which is converted from phenylalanine by the rate-limiting enzyme phenylalanine hydroxylase (PAH). While the role of tyrosine, derived from phenylalanine, in the synthesis of fiber proteins has long been known, the role of PAH in melanin synthesis is still unknown in silkworm. To define the importance of PAH, we cloned the cDNA sequence of BmPAH and expressed its complete coding sequence using the Bac-to-Bac baculovirus expression system. Purified recombinant protein had high PAH activity, some tryptophan hydroxylase activity, but no tyrosine hydroxylase activity, which are typical properties of PAH in invertebrates. Because melanin synthesis is most robust during the embryonic stage and larval integument recoloring stage, we injected BmPAH dsRNA into silkworm eggs and observed that decreasing BmPAH mRNA reduced neonatal larval tyrosine and caused insect coloration to fail. In vitro cultures and injection of 4th instar larval integuments with PAH inhibitor revealed that PAH activity was essential for larval marking coloration. These data show that BmPAH is necessary for melanin synthesis and we propose that conversion of phenylalanine to tyrosine by PAH is the first step in the melanin biosynthetic pathway in the silkworm. PMID:23991017

Chen, Ping; Li, Li; Wang, Jiying; Li, Haiyin; Li, Yan; Lv, Yin; Lu, Cheng

2013-01-01

328

Passive sampling for the monitoring of organic pollutants (PAHs, BTEX) in groundwater. Application to a former  

E-print Network

Passive sampling for the monitoring of organic pollutants (PAHs, BTEX) in groundwater. Application) for respectively the estimation of PAHs and BTEX concentrations in groundwater at a former industrial site. Results were compared with those from classical analysis (LC/UV/fluorescence and ITEX/GC/MS for PAHs and BTEX

Boyer, Edmond

329

THE COMPUTED INFRARED SPECTRA OF A VARIETY OF [FePAH]{sup +} COMPLEXES: MID- AND FAR-INFRARED FEATURES  

SciTech Connect

The effects of the pi-coordination of an Fe atom on the mid- and far-infrared spectra of a mixture of cationic polycyclic aromatic hydrocarbons (PAHs), e.g., pyrene (C{sub 16}H{sub 10}), anthanthrene (C{sub 22}H{sub 12}), coronene (C{sub 24}H{sub 12}), ovalene (C{sub 32}H{sub 14}), circumpyrene (C{sub 42}H{sub 16}), and circumcoronene (C{sub 54}H{sub 18}), are studied by Density Functional Theory based calculations. In the mid-infrared range (3-20 {mu}m), by comparison with the bare PAH{sup +} spectrum, we found (1) an increase of the intensity ratio of the C-H stretching and C-H out-of-plane bending bands with respect to the intense CC stretching band and (2) a shift of the band positions and a characteristic profile with a steep blue rise and an extended red tail for the CC stretching and CH out-of-plane bending bands. None of these features appears inconsistent with the observed aromatic infrared band spectrum. In the far-infrared range (lambda > 20 {mu}m), the presence of a pi-coordinated Fe atom induces many new bands as (1) some vibrational modes of the PAH are activated due to symmetry reduction and (2) new modes involving the motion of the Fe atom occur. In particular, an accumulation point due to the activation of the Fe-PAH stretching mode is observed at around 40 {mu}m. This range is suggested to contain the spectral fingerprint for the presence of [M-PAH]{sup +} (M=Fe, Si, Mg) complexes in the interstellar medium. Additional features in the [60-300] {mu}m range are found for complexes with large PAHs. The obtained results are discussed in the light of past, present, and future astronomical missions, among which are the Herschel Space Observatory and the SPICA telescope for the far-infrared domain.

Simon, A.; Joblin, C. [Universite de Toulouse, UPS, CESR, 9 Av. du Colonel Roche, 31028 Toulouse Cedex 4, France. (France)

2010-03-20

330

Theoretical Investigation of PAHs: Implications to Diffuse Interstellar Bands  

NASA Astrophysics Data System (ADS)

About a thousand optical absorption features on the interstellar extinction curve popularly known as the Diffuse Interstellar Bands (DIBs) have been observed. The numbers are increasing every year, thanks to the improvement in telescope and spectroscopic technology. Ultra-high resolution spectroscopic observations and emission features corresponding to some of the DIBs suggest that, some if not all, of these features are due to large molecules. The strength of DIBs depend on the amount of reddening which is directly proportional to the amount of material present between the background star and the observer. Since, the strengths of the DIBs are not strongly correlated with each other, there must be several carriers. Time Dependent Density Functional Theory (TDDFT) calculations are useful in narrowing down molecular systems that may be further investigated in the laboratory. The observations of the unidentified infrared (UIR) bands point towards the widespread presence of Polycyclic Aromatic Hydrocarbon (PAH) molecules. Though, not a single PAH has been discovered in interstellar space, these are the largest molecules suspected to be present. PAHs are stable towards energetic environment prevailing under interstellar conditions rendering these molecules to be good candidates as DIB carriers. We report TDDFT calculations to predict electronic transitions of neutral, protonated-deuteronated and PAHs with five member rings with various sites of protonation and deuteronation. 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 and laboratory studies are warranted for these systems.

Pathak, A.; Buragohain, M.; Hammonds, M.; Sarre, P. J.

2014-02-01

331

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

332

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

333

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

334

Photochemistry of Polycyclic Aromatic Hydrocarbons in Cosmic Water Ice: The Role of Pah Ionization and Concentration  

NASA Astrophysics Data System (ADS)

Infrared spectroscopic studies of ultraviolet (UV) irradiated, water-rich, cosmic ice analogs containing small polycyclic aromatic hydrocarbons (PAHs) are described. The irradiation studies of anthracene:H2O, pyrene:H2O, and benzo[ghi]perylene:H2O ices (14 K) at various concentrations reported by Bouwman et al. are extended. While aromatic alcohols and ketones have been reported in residues after irradiated PAH:H2O ices were warmed to 270 K, it was not known if they formed during ice irradiation or during warm-up when reactants interact as H2O sublimes. Recent work has shown that they form in low temperature ice. Using DFT computed IR spectra to identify photoproducts and PAH cations, we tentatively identify the production of specific alcohols [PAH(OH) n ] and quinones [PAH(O) n ] for all PAH:H2O ices considered here. Little evidence is found for hydrogenation at 14 K, consistent with the findings of Gudipati & Yang. Addition of O and OH to the parent PAH is the dominant photochemical reaction, but PAH erosion to smaller PAHs (producing CO2 and H2CO) is also important. DFT spectra are used to assess the contribution of PAH-related species to interstellar absorption features from 5 to 9 ?m. The case is made that PAH cations are important contributors to the C2 component and PAH(OH) n and PAH(O) n to the C5 component described by Boogert et al. Thus, interstellar ices should contain neutral and ionized PAHs, alcohols, ketones and quinones at the ~2%-4% level relative to H2O. PAHs, their photoproducts, and ion-mediated processes should therefore be considered when modeling interstellar ice processes.

Cook, Amanda M.; Ricca, Alessandra; Mattioda, Andrew L.; Bouwman, Jordy; Roser, Joseph; Linnartz, Harold; Bregman, Jonathan; Allamandola, Louis J.

2015-01-01

335

Characteristics and sources of atmospheric polycyclic aromatic hydrocarbons (PAHs) in Shanghai, China.  

PubMed

A field campaign was conducted to measure and analyze 13 polycyclic aromatic hydrocarbons (PAHs) in six major zones in the city of Shanghai, P.R. China from August 2006 to April 2007. Ambient air samples were collected seasonally using passive air samplers, and gas chromatography-mass spectroscopy was used in this field campaign. The results showed that there was a sequence of 13 PAHs at Phen > FA > Pyr > Chr > Fl > An > BaA > BbFA > BghiP > IcdP > BkFA > BaP > DahA and the sum of these PAHs is 36.01 +/- 10.85 ng/m(3) in gas phase. FL, Phen, FA, Pyr, and Chr were the dominant PAHs in gas phase in the city. They contributed 90% of total PAHs in the gas phase. Proportion of measured PAHs with three, four, five, and six rings to total PAHs was 53%, 42%, 3%, and 2%, respectively. The highest concentration of SigmaPAHs (the sum of 13 PAHs) occurred in the wintertime and the lowest was in the summer. This investigation suggested that traffic, wood combustion, and metal scrap burn emissions were dominant sources of the concentrations of PAHs in six city zones compared with coal burning and industry emissions. Further, the traffic emission sources of PAHs in the city were attributed mostly to gasoline-powered vehicles compared with diesel-powered vehicles. It was revealed that the seasonal changes in PAHs in the city depended on different source types. Metal scrap burn was found to be the major source of PAHs during the autumn, while the PAH levels in the atmosphere for winter and spring seasons were mainly influenced by wood and biomass combustion. Comparisons of PAHs among different city zones and with several other cities worldwide were also made and discussed. PMID:19440848

Wang, Xian Yu; Li, Qing Bo; Luo, Yong Ming; Ding, Qian; Xi, Lian Min; Ma, Jian Min; Li, Yan; Liu, Yi Peng; Cheng, Cui Li

2010-06-01

336

Combined use of PAH levels and EROD activities in the determination of PAH pollution in flathead mullet (Mugil cephalus) caught from the West Black Sea coast of Turkey.  

PubMed

The aim of this study was to determine the extent of polycyclic aromatic hydrocarbon (PAH) pollution by measuring PAH levels and 7-ethoxyresorufin-O-deethylase (EROD) activities in flathead mullet (Mugil cephalus) samples caught from the West Black Sea coast of Turkey. The fish samples were caught in August 2008-2011. The levels of 13 PAHs were measured by high-performance liquid chromatography (HPLC) in the liver of fish. Most of the measured PAHs had three rings (low molecular weight). The frequencies of detection of PAHs were higher in fish samples caught from Zonguldak Harbour and Gülüç Stream Mouth than those from Sakarya River Mouth, Amasra and Kefken. EROD activities and cytochrome P4501A (CYP1A) protein level were also measured in the fish liver microsomes. Highly elevated EROD activities and CYP1A levels were measured in the mullet samples caught from Zonguldak Harbour and Gülüç Stream than those from Amasra and Kefken. The detection of PAHs in the liver of fish samples shows recent exposure to PAHs. The chemical analyses of PAHs and EROD activity results together reflected the extent of PAH pollution in the livers of fish caught from the West Black Sea coast of Turkey. The results indicate that Zonguldak Harbour is the most polluted site in the West Black Sea coast of Turkey. PMID:25339526

Bozcaarmutlu, Azra; Sapmaz, Canan; Kaleli, Gizem; Turna, Sema; Yenisoy-Karaka?, Serpil

2015-02-01

337

Hydrocarbon, PAH and PCB emissions from ferries: A case study in the Skagerak-Kattegatt-Öresund region  

NASA Astrophysics Data System (ADS)

Hydrocarbon speciation measurements have been carried out on board two passenger ferries (medium speed, four-stroke diesel main engines) operating in the Skagerak-Kattegatt-Öresund region. Average emission factors for 20 light-weight hydrocarbons (C 2-C 6), 12 medium-weight hydrocarbons (C 6-C 12), 23 polycyclic aromatic hydrocarbons (PAH), 7 polychlorinated biphenyls (PCB) and hexachlorbenzene (HCB) were determined for a situation with varying engine loads and a short service route ( MS Aurora, Helsingborg-Helsingor) and a case with a longer service route and more constant engine loads ( Stena Danica, Goteborg-Fredrikshavn). In general, ethene, propene, isobutene, benzene and C 9?C 12 alkanes dominated the hydrocarbon compositions measured, although their relative proportions differed between the two ferries. The PCB emissions measured were relatively small which is probably a reflection of the low Cl content in the fuel and gas oils used. The levels of PAH detected appear, however, to be of significance; the total PAH group accounted for ca. 1 % of the total hydrocarbon emission. It is roughly estimated that ferry traffic in the Skagerak-Kattegatt-Öresund region accounts for ca. 5 t PAH and ca. 1 kg PCB per year. In line with previous estimates of marine emissions, NO x emissions from the ferries were quite significant and this represents an important source in the study area. Since average hydrocarbon emission rates were only ca. 1 % of the NO x emissions, tropospheric ozone formation will be more dependent on the NO x emissions irrespective of the composition of the emitted hydrocarbons. In addition, the low HC/NO x ratio in the emissions also indicates that the possible contribution of ferry traffic emissions to hydrocarbon measurements at coastal stations is not very significant.

Cooper, D. A.; Peterson, K.; Simpson, D.

338

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

PubMed Central

Polycyclic aromatic hydrocarbons (PAHs) are combustion products of organic materials, mixtures of which contain multiple known and probable human carcinogens. PAHs occur in indoor and outdoor air, as well as in char-broiled meats and fish. Human exposure to PAHs occurs by inhalation, ingestion and topical absorption, and subsequently formed metabolites are either rendered hydrophilic and excreted, or bioactivated and bound to cellular macromolecules. The formation of PAH-DNA adducts (DNA binding products), considered a necessary step in PAH-initiated carcinogenesis, has been widely studied in experimental models and has been documented in human tissues. This review describes immunohistochemistry (IHC) studies, which reveal localization of PAH-DNA adducts in human tissues, and semi-quantify PAH-DNA adduct levels using the Automated Cellular Imaging System (ACIS). These studies have shown that PAH-DNA adducts concentrate in: basal and supra-basal epithelium of the esophagus, cervix and vulva; glandular epithelium of the prostate; and cytotrophoblast cells and syncitiotrophoblast knots of the placenta. The IHC photomicrographs reveal the ubiquitous nature of PAH-DNA adduct formation in human tissues as well as PAH-DNA adduct accumulation in specific, vulnerable, cell types. This semi-quantative method for PAH-DNA adduct measurement could potentially see widespread use in molecular epidemiology studies. PMID:21845152

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

2011-01-01

339

Survey of polycyclic aromatic hydrocarbons (PAHs) in arterial street air of Hangzhou.  

PubMed

The presence of particulate and vapor PAHs, SO2 and NOx and other interrelated conditions (temperature, traffic intensity and wind velocity) were investigated in the arterial street air of Hangzhou. The concentration of the nine PAHs in the air was mean to 11.7 micrograms/m3, and the content of benzo(a) pyrene was up to 0.108 microgram/m3. The contents of PAHs in the sampling sites were in good relation to the traffic intensity, and would be also affected by the terrain and meteorological conditions. The occurrences of PAHs in ambient air were mainly affected by their physical, chemical characters and temperature. The three- and four-ring PAHs (MW < or = 228) mainly existed in the vapor phase and the five-ring PAHs (MW > 228) existed predominately in the particulate phase. The fraction of vapor PAHs in the total nine PAHs was 84.2% in the air of the sampling sites. In the morning and evening, the concentrations of PAHs in the arterial street air were higher than that on the noon and the diurnal variation of PAHs was similar to that of the traffic gas NOx. A conclusion would be drawn that the major source of PAHs in the arterial street air was the traffic. And the results indicated that 75% of BaP would come from traffic source and remaining 25% of BaP would come from non-traffic source. PMID:11590725

Zhu, L Z; Liu, Y J

2001-01-01

340

Ecotoxicological risk of polycyclic aromatic hydrocarbons (PAHs) in urban soil of Isfahan metropolis, Iran.  

PubMed

Concentration, distribution, probable sources, and health risks of 16 polycyclic aromatic hydrocarbons (PAHs) were investigated in 52 soil samples collected within a radius 50 km from Isfahan metropolis center. Total concentration of PAHs ranged from 57.70 to 11,730.08 ?g/kg averaging 2,000.56 ?g/kg. Spatial PAH profiles were site-specific and higher concentration of PAHs was observed in the vicinity of industrial zones within Isfahan metropolis. The molecular indices, ring classes, and principal component analysis indicated that the sources of PAHs were both geogenic and pyrogenic. The incremental lifetime cancer risks of exposure to soil PAHs for adults and children living in the study area were 2.3?×?10(-2) and 2.2?×?10(-3), respectively. The results suggest that current PAHs levels in Isfahan metropolis soil are highly carcinogenic and may hold a serious health risk for local resident. PMID:25805371

Moore, F; Akhbarizadeh, R; Keshavarzi, B; Khabazi, S; Lahijanzadeh, A; Kermani, M

2015-04-01

341

A Critical Review about the Health Risk Assessment of PAHs and Their Metabolites in Foods.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) are a family of toxicants that are ubiquitous in the environment. These contaminants generate considerable interest, because some of them are highly carcinogenic in laboratory animals and have been implicated in breast, lung, and colon cancers in humans. Dietary intake of PAHs constitutes a major source of exposure in humans. Factors affecting the accumulation of PAHs in the diet, their absorption following ingestion, and strategies to assess risk from exposure to these hydrocarbons following ingestion have received very little attention. This review, therefore, focuses on concentrations of PAHs in widely consumed dietary ingredients along with gastrointestinal absorption rates in humans. Metabolism and bioavailability of PAHs in animal models and the processes, which influence the disposition of these chemicals, are discussed. Finally, based on intake, disposition, and tumorigenesis data, the exposure risk to PAHs from diet is presented. This information is expected to provide a framework for refinements in risk assessment of PAHs. PMID:24915328

Yebra-Pimentel, Iria; Fernández-González, Ricardo; Martínez-Carballo, Elena; Simal-Gándara, Jesús

2015-08-24

342

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

PubMed

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

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

2011-09-01

343

Lung cancer risk from PAHs emitted from biomass combustion.  

PubMed

This study deals with the assessment of the cancer risk attributable to PAH exposure, attributable to the increased use of biomass for space heating in Greece in the winter of 2012-2013. Three fractions of particulates (PM1, PM2.5 and PM10) were measured in two sampling sites (urban/residential and traffic-influenced) followed by chemical analysis of 19 PAHs and levoglucosan (used as a biomarker tracer). PAH-induced lung cancer risk was estimated by a comprehensive methodology that incorporated human respiratory tract deposition modelling in order to estimate the toxic equivalent concentration (TEQ) at each target tissue. This allowed us to further differentiate internal exposure and risk by age groups. Results showed that all PM fractions are higher in Greece during the cold months of the year, mainly due to biomass use for space heating. PAH and levoglucosan levels were highly correlated, indicating that particles emitted from biomass combustion are more toxic than PM emitted from other sources. The estimated lung cancer risk was non-negligible for residents close to the urban background monitoring site. Higher risk was estimated for infants and children, due to the higher bodyweight normalized dose and the human respiratory tract (HRT) physiology. HRT structure and physiology in youngsters favor deposition of particles that are smaller and more toxic per unit mass. In all cases, the estimated risk (5.7E-07 and 1.4E-06 for the urban background site and 1.4E-07 to 5.0E-07 for the traffic site) was lower to the one estimated by the conventional methodology (2.8E-06 and 9.7E-07 for the urban background and the traffic site respectively) that is based on Inhalation Unit Risk; the latter assumes that all PAHs adsorbed on particles are taken up by humans. With the methodology proposed herein, the estimated risk presents a 5-7 times difference between the two sampling sites (depending on the age group). These differences could not have been identified had we relied only on conventional risk assessment method. Consequently, the actual cancer risk attributable to PAHs on PM emitted from biomass burning would have been significantly underestimated. PMID:25543545

Sarigiannis, Dimosthenis ?; Karakitsios, Spyros P; Zikopoulos, Dimitrios; Nikolaki, Spyridoula; Kermenidou, Marianthi

2015-02-01

344

Rotorcraft Diagnostics  

NASA Technical Reports Server (NTRS)

Health management (HM) in any engineering systems requires adequate understanding about the system s functioning; a sufficient amount of monitored data; the capability to extract, analyze, and collate information; and the capability to combine understanding and information for HM-related estimation and decision-making. Rotorcraft systems are, in general, highly complex. Obtaining adequate understanding about functioning of such systems is quite difficult, because of the proprietary (restricted access) nature of their designs and dynamic models. Development of an EIM (exact inverse map) solution for rotorcraft requires a process that can overcome the abovementioned difficulties and maximally utilize monitored information for HM facilitation via employing advanced analytic techniques. The goal was to develop a versatile HM solution for rotorcraft for facilitation of the Condition Based Maintenance Plus (CBM+) capabilities. The effort was geared towards developing analytic and reasoning techniques, and proving the ability to embed the required capabilities on a rotorcraft platform, paving the way for implementing the solution on an aircraft-level system for consolidation and reporting. The solution for rotorcraft can he used offboard or embedded directly onto a rotorcraft system. The envisioned solution utilizes available monitored and archived data for real-time fault detection and identification, failure precursor identification, and offline fault detection and diagnostics, health condition forecasting, optimal guided troubleshooting, and maintenance decision support. A variant of the onboard version is a self-contained hardware and software (HW+SW) package that can be embedded on rotorcraft systems. The HM solution comprises components that gather/ingest data and information, perform information/feature extraction, analyze information in conjunction with the dependency/diagnostic model of the target system, facilitate optimal guided troubleshooting, and offer decision support for optimal maintenance.

Haste, Deepak; Azam, Mohammad; Ghoshal, Sudipto; Monte, James

2012-01-01

345

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

346

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

USGS Publications Warehouse

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

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

2012-01-01

347

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

PubMed

The effects of interactions between genetic materials and polycyclic aromatic hydrocarbons (PAHs) on gene expression in the extracellular environment remain to be elucidated and little information is currently available on the effect of ionic strength on the transformation of plasmid DNA exposed to PAHs. Phenanthrene and pyrene were used as representative PAHs to evaluate the transformation of plasmid DNA after PAH exposure and to determine the role of Ca(2+) during the transformation. Plasmid DNA exposed to the test PAHs demonstrated low transformation efficiency. In the absence of PAHs, the transformation efficiency was 4.7 log units; however, the efficiency decreased to 3.72-3.14 log units with phenanthrene/pyrene exposures of 50 µg · L(-1). The addition of Ca(2+) enhanced the low transformation efficiency of DNA exposed to PAHs. Based on the co-sorption of Ca(2+) and phenanthrene/pyrene by DNA, we employed Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and mass spectrometry (MS) to determine the mechanisms involved in PAH-induced DNA transformation. The observed low transformation efficiency of DNA exposed to either phenanthrene or pyrene can be attributed to a broken hydrogen bond in the double helix caused by planar PAHs. Added Ca(2+) formed strong electrovalent bonds with "-POO(-)-" groups in the DNA, weakening the interaction between PAHs and DNA based on weak molecular forces. This decreased the damage of PAHs to hydrogen bonds in double-stranded DNA by isolating DNA molecules from PAHs and consequently enhanced the transformation efficiency of DNA exposed to PAH contaminants. The findings provide insight into the effects of anthropogenic trace PAHs on DNA transfer in natural environments. PMID:23484001

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

2013-01-01

348

Photo-induced toxicity of PAHs to Hyalella azteca and Chironomus tentans: effects of mixtures and behavior  

Microsoft Academic Search

In the aquatic environment, polycyclic aromatic hydrocarbon (PAH) contamination can result from several anthropogenic sources such as petroleum runoff, industrial processes, and petroleum spills. When ultraviolet light (UV) is present at sufficient intensity, the acute toxicity of some PAHs to aquatic biota is greatly enhanced. This photo-induced toxicity of PAHs is directly influenced by the amount of PAH and by

A. C. Hatch; G. A. Burton

1999-01-01

349

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

350

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

351

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

352

Comparing PAH availability from manufactured gas plant soils and sediments with chemical and biological tests. 1. PAH release during water desorption and supercritical carbon dioxide extraction.  

PubMed

Soil and sediment samples from oil gas (OG) and coal gas (CG) manufactured gas plant (MGP) sites were selected to represent a range of PAH concentrations (150-40,000 mg/kg) and sample matrix compositions. Samples varied from vegetated soils to lampblack soot and had carbon contents from 3 to 87 wt %. SFE desorption (120 min) and water/XAD2 desorption (120 days) curves were determined and fit with a simple two-site model to determine the rapid-released fraction (F) for PAHs ranging from naphthalene to benzo[ghi]perylene. F values varied greatly among the samples, from ca. 10% to >90% for the two- and three-ring PAHs and from <1% to ca. 50% for the five- and six-ring PAHs. Release rates did not correlate with sample matrix characteristics including PAH concentrations, elemental composition (C, H, N, S), or "hard" and "softs" organic carbon, indicating that PAH release cannot easily be estimated on the basis of sample matrix composition. Fvalues for CG site samples obtained with SFE and water desorption agreed well (linear correlation coefficient, r2 = 0.87, slope = 0.93), but SFE yielded higher F values for the OG samples. These behaviors were attributed to the stronger ability of carbon dioxide than water to desorb PAHs from the highly aromatic (hard) carbon of the OG matrixes, while carbon dioxide and water showed similar abilities to desorb PAHs from the more polar (soft) carbon of the CG samples. The combined SFE and water desorption approaches should improve the understanding of PAH sequestration and release from contaminated soils and sediments and provide the basis for subsequent studies using the same samples to compare PAH release with PAH availability to earthworms. PMID:12487302

Hawthorne, Steven B; Poppendieck, Dustin G; Grabanski, Carol B; Loehr, Raymond C

2002-11-15

353

Cells on fibers to degrade PAH and upgrade coal  

SciTech Connect

There are over 2000 sites contaminated with PAH`s from coal burning plants. White rot fungus degrades phenanthrene and anthracene, but the fungus needs air to grow. When grown on old cardboard boxes and buried, air is entrapped in the corrugations for growth of the fungus. When holes are put in the valleys of the corrugations and rotated in a half full reactor, drops are formed. Mass transfer to drops is much faster than to a flat surface, as described in Patent 5,256,570, so the fungus grows faster. Low rank coal can be upgraded to more valuable products with the fungus, say some Australians, but the problem is supplying oxygen. Celite can be entrapped in the fibers to ferment coal derived synthesis gas. The paper describes these processes.

Clyde, R.

1997-12-31

354

PAHs biodegradation in intertidal surface sediment by indigenous microorganisms.  

PubMed

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

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

2014-05-01

355

Carbon X-ray Raman Spectroscopy of PAHs and Asphaltenes  

Microsoft Academic Search

The application of x-ray Raman spectroscopy (XRRS) to gain information about the local structure of carbonaceous systems including\\u000a complex polycyclic aromatic hydrocarbons (PAHs) and asphaltenes is discussed in this chapter. This novel approach to directly\\u000a probe carbon type in such systems has become practical only recently with the help of intense new synchrotron x-ray sources\\u000a and innovation in spectrograph design.

Uwe Bergmann; Oliver C. Mullins

356

Semipermeable membrane devices accumulate conserved ratios of sterane and hopane petroleum biomarkers.  

PubMed

Semipermeable membrane devices (SPMDs) are commonly used as a time-integrated measure of aqueous concentrations of persistent hydrophobic chemicals, including PAH, pesticides, dioxins, and PCBs. Another class of persistent hydrophobic chemicals is petroleum biomarker compounds (hopanes and steranes) that are used for hydrocarbon source identification and allocation. In this study three different passive sampling device designs were exposed to a complex hydrocarbon mixture (Alaska North Slope crude) in a laboratory experiment to determine uptake rates of biomarkers into SPMDs. In addition to the standard triolein filled SPMDs, iso-octane filled SPMDs (ISPMDs) and unfilled low-density polyethylene strips (PESDs) were tested. Uptake rates and effective sampling rates were determined for 53 compounds. There was little variation in sampling rates among the individual biomarkers; average values (ld(-1)) for hopanes were 0.43+/-0.07 (PESD), 0.33+/-0.06 (SPMD), and 0.44+/-0.03 (ISPMD) and average sterane sampling rates were 0.57+/-0.04 (PESD), 0.42+/-0.03 (SPMD), and 0.53+/-0.03 (ISPMD). The primary reason for biomarker analysis is for source discrimination of petroleum. Nineteen different diagnostic ratios were measured, and were found to be remarkably well conserved between the oil, water, and all three devices. This indicates that SPMDs, PESDs, and ISPMDs should each be effective for source discrimination studies of petroleum contamination. PMID:13129510

Luellen, Drew R; Shea, Damian

2003-11-01

357

Polycyclic aromatic hydrocarbons (PAHs) in the air of Chinese cities.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) were determined in the air of 37 cities and 3 rural locations across China during the winter, spring, summer and autumn of 2005, using polyurethane foam (PUF) disks as passive air samplers (PAS). Winter and autumn concentrations in cities exceeded spring and summer values. Concentrations were amongst the highest in the world; seasonally averaged autumn/winter values in some cities in the north and north-west of China exceeded proposed European Union air quality standards. Several factors, acting in combination, influenced air concentrations. A significant negative correlation was found between average annual city concentrations and the annual average temperature, while winter time PAH concentrations correlated with estimated coal consumption. The highest total PAH concentrations and loadings of high molecular weight compounds generally occurred in major cities located on higher land (500-2000 m), where relatively cold winters and higher coal consumption occurs. Lower values occurred in cities located in the south and east China and along the coastal regions. Molecular markers indicated incomplete combustion of fossil fuels dominated the urban air and gave evidence for photo-decomposition of selected compounds. PMID:17909643

Liu, Xiang; Zhang, Gan; Li, Jun; Cheng, Hai-Rong; Qi, Shi-Hua; Li, Xiang-Dong; Jones, Kevin C

2007-10-01

358

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

359

Further insights into the composition, source, and toxicity of PAHs in size-resolved particulate matter in a megacity in China.  

PubMed

Concentrations of particulate matter with an aerodynamic diameter less than 10 ?m (PM10 ) and PM with an aerodynamic diameter less than 2.5 ?m (PM2.5 ), and 16 polycyclic aromatic hydrocarbons (PAHs) were measured. The average concentrations of PM10 and PM2.5 reached 209.75??g/m(3) and 141.87??g/m(3) , respectively, and those of ?PAHs were 41.46?ng/m(3) for PM10 and 36.77?ng/m(3) for PM2.5 . The mass ratio concentrations were 219.23??g/g and 311.01??g/g in PM10 and PM2.5 , respectively. Three sources and their contributions for PAHs were obtained. For individual input mode, diesel exhaust contributed 46.77% (PM10 ) and 41.12% (PM2.5 ) for mass concentration and 48.69% (PM10 ) and 39.47% (PM2.5 ) for mass ratio concentration; gasoline exhaust contributed 31.02% (PM10 ) and 39.47% (PM2.5 ) for mass concentration and 28.95% (PM10 ) and 36.46% (PM2.5 ) for mass ratio concentration; and coal combustion contributed 22.22% (PM10 ) and 19.41% (PM2.5 ) for mass concentration and 22.36% (PM10 ) and 15.89% (PM2.5 ) for mass ratio concentration. For combined input mode, the same source categories were obtained. Source contributions to PM10 and PM2.5 were diesel exhaust (40.70% and 36.64%, respectively, for mass concentration; 49.19% and 38.47%, respectively, for mass ratio concentration), gasoline exhaust (35.09% and 38.47%, respectively, for mass concentration; 32.50% and 33.43%, respectively, for mass ratio concentration), and coal combustion (24.21% and 24.89%, respectively, for mass concentration; 18.31% and18.17%, respectively, for mass ratio concentration). Source risk assessment showed that vehicle emission was a significant contributor. The findings can help elucidate sources of PAHs and provide evidence supporting further applications of the Unmix model and additional studies about PAHs. Environ Toxicol Chem 2015;34:480-487. © 2014 SETAC. PMID:25400005

Shi, Guo-Liang; Zhou, Xiao-Yu; Jiang, Su-Yang; Tian, Ying-Ze; Liu, Gui-Rong; Feng, Yin-Chang; Chen, Gang; Liang, Yang-Ke-Xin

2015-03-01

360

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

361

PAH charge state distribution and DIB carriers: Implications from the line of sight toward HD 147889  

NASA Astrophysics Data System (ADS)

We have computed physical parameters such as density, degree of ionization and temperature, constrained by a large observational data set on atomic and molecular species, for the line of sight toward the single cloud HD 147889. Diffuse interstellar bands (DIBs) produced along this line of sight are well documented and can be used to test the PAH hypothesis. To this effect, the charge state fractions of different polycyclic aromatic hydrocarbons (PAHs) are calculated in HD 147889 as a function of depth for the derived density, electron abundance and temperature profile. As input for the construction of these charge state distributions, the microscopic properties of the PAHs, e.g., ionization potential and electron affinity, are determined for a series of symmetry groups. The combination of a physical model for the chemical and thermal balance of the gas toward HD 147889 with a detailed treatment of the PAH charge state distribution, and laboratory and theoretical data on specific PAHs, allow us to compute electronic spectra of gas phase PAH molecules and to draw conclusions about the required properties of PAHs as DIB carriers. We find the following. 1) The variation of the total charge state distribution of each specific class (series) of PAH in the translucent cloud toward HD 147889 (and also of course for any other diffuse/translucent cloud) depends strongly on the molecular symmetry and size (number of ? electrons). This is due to the strong effects of these parameters on the ionization potential of a PAH. 2) Different wavelength regions in the DIB spectrum are populated preferentially by different PAH charge states depending on the underlying PAH size distribution. 3) The PAH size distribution for HD 147889 is constrained by the observed DIB spectrum to be Gaussian with a mean of 50 carbon atoms. 4) For the given PAH size distribution it is possible to constrain the total small catacondensed PAH column density along the line of sight to HD 147889 to 2.4×1014 cm-2 by comparing the total observed UV extinction to the strong UV absorptions of neutral PAHs in the 2000-3000 Å region. 5) Catacondensed PAHs with sizes above some 40 C-atoms are expected to show strong DIBS longward of 10 000 Å. Large condensed PAHs in the series, pyrene, coronene, ovalene, .... , on the other hand, mainly absorb between 4000 and 10 000 Å but extrapolation to even larger pericondensed PAHs in this series also shows strong absorptions longward of 10 000 Å. 6) Only the weak DIBs in HD 147889 could be reproduced by a mix of small catacondensed PAHs (<50 C atoms) while for large pericondensed PAHs (50 < C atoms < 100) the intermediate DIBs are well reproduced. Small catacondensed PAHs cannot contribute more than 50% of the total observed equivalent width toward HD 147889. Strong DIBs can only be reproduced by addition of very specific PAH molecules or homologue series to the sample set (i.e., a small number of PAHs with high oscillator strength or a large number of PAHs with a low oscillator strength). An outline is provided for a more general application of this method to other lines of sight, which can be used as a pipeline to compute the spectroscopic response of a PAH or group of PAHs in a physical environment constrained by independent (non-DIB) observations. Based on observations made at the European Southern Observatory, Paranal, Chile (ESO programs 67.C-0281 and 64.H-0224). Appendices A-C are only available in electronic form at http://www.edpsciences.org

Ruiterkamp, R.; Cox, N. L. J.; Spaans, M.; Kaper, L.; Foing, B. H.; Salama, F.; Ehrenfreund, P.

2005-03-01

362

Biodiesel emissions profile in modern diesel vehicles. Part 2: Effect of biodiesel origin on carbonyl, PAH, nitro-PAH and oxy-PAH emissions.  

PubMed

In the present study, the effects of different biodiesel blends on the unregulated emissions of a Euro 4 compliant passenger car were examined. Two fresh and two oxidized biodiesel fuels of different source materials were blended with an ultra low sulphur automotive diesel fuel at proportions of 10, 20, and 30% v/v. Emission measurements were conducted on a chassis dynamometer with a constant volume sampling (CVS) technique, over the New European Driving Cycle (NEDC) and the Artemis driving cycles. The experimental results revealed that the addition of biodiesel led to important increases in most carbonyl compounds. Sharp increases were observed with the use of the oxidized biodiesel blends, especially those prepared from used frying oil methyl esters. Similar to carbonyl emissions, most PAH compounds increased with the addition of the oxidized biodiesel blends. It can be assumed that the presence of polymerization products and cyclic acids, along with the degree of unsaturation were the main factors that influenced carbonyl and PAH emissions profile. PMID:21122895

Karavalakis, Georgios; Boutsika, Vasiliki; Stournas, Stamoulis; Bakeas, Evangelos

2011-01-15

363

Genotoxicity of oxy-PAHs to Japanese medaka (Oryzias latipes) embryos assessed using the comet assay.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) have long been recognized as important environmental toxicants. Despite a plethora of information on the fate and effects of parent PAHs, relatively little is known about the environmental fate and toxicity of ketone- and quinone-substituted PAH oxidation products (termed oxy-PAHs), particularly in the aquatic environment. This study begins to fill that gap using embryos of the Japanese medaka (Oryzias latipes) as a model species. The genotoxic potential of two environmentally relevant oxy-PAHs, acenaphthenequinone and 7,12-benz[a]anthracenquinone, was assessed using the comet assay. We found that both oxy-PAHs could cause significant increases in DNA damage after only 48 h of exposure at the lowest concentrations tested (5 ?g/L). Comparisons of the genotoxic potential between these oxy-PAHs and their corresponding parent PAHs (acenaphthene and benz[a]anthracene) and a well-known mutagenic PAH, benzo[a]pyrene, indicated similar potencies among all five of these compounds, particularly after longer (7 day) exposures. This study demonstrates the mutagenic potential of oxy-PAHs to an in vivo fish embryo model and points out the need for further study of their environmental occurrence and biologic effects. PMID:24510601

Dasgupta, Subham; Cao, Austin; Mauer, Brittany; Yan, Beizhan; Uno, Seiichi; McElroy, Anne

2014-12-01

364

Anaerobic biodegradation of PAHs in mangrove sediment with amendment of NaHCO3.  

PubMed

Mangrove sediment is unique in chemical and biological properties. Many of them suffer polycyclic aromatic hydrocarbon (PAH) contamination. However, the study on PAH biological remediation for mangrove sediment is deficient. Enriched PAH-degrading microbial consortium and electron acceptor amendment are considered as two effective measures. Compared to other electron acceptors, the study on CO2, which is used by methanogens, is still seldom. This study investigated the effect of NaHCO3 amendment on the anaerobic biodegradation of four mixed PAHs, namely fluorene (Fl), phenanthrene (Phe), fluoranthene (Flua) and pyrene (Pyr), with or without enriched PAH-degrading microbial consortium in mangrove sediment slurry. The trends of various parameters, including PAH concentrations, microbial population size, electron-transport system activities, electron acceptor and anaerobic gas production were monitored. The results revealed that the inoculation of enriched PAH-degrading consortium had a significant effect with half lives shortened by 7-13days for 3-ring PAHs and 11-24days for 4-ring PAHs. While NaHCO3 amendment did not have a significant effect on the biodegradation of PAHs and other parameters, except that CO2 gas in the headspace of experimental flasks was increased. One of the possible reasons is that mangrove sediment contains high concentrations of other electron acceptors which are easier to be utilized by anaerobic bacteria, the other one is that the anaerobes in mangrove sediment can produce enough CO2 gas even without adding NaHCO3. PMID:25872721

Li, Chun-Hua; Wong, Yuk-Shan; Wang, Hong-Yuan; Tam, Nora Fung-Yee

2015-04-01

365

Evaluating sources of PAHs in urban streams based on land use and biomonitors.  

PubMed

Toxic polycyclic aromatic hydrocarbons (PAHs) can be found in wastewaters and sewages released from industries and/or urban areas. When discharged untreated to stream waters, they can be a problem to human health. This work represents the first attempt to use PAH and metal concentrations in aquatic moss transplants together with land-use information to identify water pollution sources in urban areas. To do this, the moss Fontinalis antipyretica was collected from a natural stream and transplanted to four different streams in a densely populated area of Lisbon, Portugal. After three months of exposure, mosses were collected and analyzed for metals and for the 16 priority PAHs recommended by the U.S. EPA. Urban streams seem to have a scattered contamination of 6-ring PAHs. Correlations among land-use, metal concentrations, and PAH concentrations indicated that areas occupied by activities of tertiary and industrial sectors had higher PAH concentrations in transplanted mosses, mainly for the sum of the 16 EPA-PAHs and for the 2-, 3- and 5-ringed PAHs, than areas occupied by urban and wooded areas. These PAHs were associated with enhanced Zn and Cu and land use activities that linked the sites to high traffic density. Industrial land use influences PAH concentration in water up to 1000 m of distance from the stream, whereas tertiary sector land use influences it up to 500 m. PMID:21410193

Augusto, Sofia; Gonzalez, Carla; Vieira, Rute; Máguas, Cristina; Branquinho, Cristina

2011-04-15

366

A step towards the use of biomonitors as estimators of atmospheric PAHs for regulatory purposes.  

PubMed

One of the main drawbacks of using lichens to monitor atmospheric PAHs has been reported as the inexistence of studies aiming to translate PAH values in lichens into the atmospheric equivalents ones, in order to use this information for regulatory purposes. In this work, PAH concentrations in lichens were compared with PAH concentrations measured in a conventional active sampler in an outdoor environment for a 9-month span. Significant positive correlations between HMW-PAHs, ?16 EPA-PAHs, and BaP equivalent concentrations in lichens and those in air (TSP) were found. Concentrations of ?16 EPA-PAHs in lichens and air showed a seasonal variation, with highest values during winter and lowest values during summer. Meteorological variables - temperature, atmospheric pressure, relative humidity, and wind speed - showed to significantly influence PAH concentrations in both lichens and air. Based on the significant linear correlations, equations for translating PAH concentrations measured in lichens into equivalent ones for air were proposed for the first time, allowing a broader use of lichens' information regarding PAHs in monitoring schemes and decision-making. PMID:23668962

Augusto, Sofia; Pereira, Maria J; Máguas, Cristina; Branquinho, Cristina

2013-07-01

367

Screening level of PAHs in sediment core from Lake Hongfeng, Southwest China.  

PubMed

Using data from a 25-year retrospective of polycyclic aromatic hydrocarbons (PAHs) in sediment core from Lake Hongfeng, Southwest China, their possible sources and potential toxicologic significance were investigated. The total PAH concentrations (16 priority PAHs as proposed by the United States Environmental Protection Agency) in sediments ranged from 2936.1 to 5282.3 ng/g and gradually increased from the analyzed deeper sediments to surface sediments. PAHs were dominated by low molecular-weight components, especially phenanthrene (PHEN) and fluorene (FLU). However, a significantly increased number of high molecular-weight (HMW) PAHs was found in upper segments. The temporal trends of individual PAH species suggest that there may have been a change in energy use from low- to high-temperature combustion, especially after approximately 2001. PAH input to Lake Hongfeng originated mainly from domestic coal combustion and biomass burning, whereas fuel combustion characteristics have also been found in recent years. Sediment-quality assessment implied that potential adverse biologic impact could be a probability for most low-ring PAHs (including naphthalene, acenaphthylene, acenaphthylene, FLU, PHEN, and anthracene). Nevertheless, more concern should be paid to HMW PAHs in the future due to their rapidly increasing trends in upper sediments. Because only one core was analyzed in this study, more work is needed to confirm the sources and toxicity of PAHs in Lake Hongfeng. PMID:20623117

Guo, Jian-Yang; Wu, Feng-Chang; Zhang, Liang; Liao, Hai-Qing; Zhang, Run-Yu; Li, Wei; Zhao, Xiao-Li; Chen, She-Jun; Mai, Bi-Xian

2011-05-01

368

Generation and distribution of PAHs in the process of medical waste incineration  

SciTech Connect

Highlights: ? PAHs generation and distribution features of medical waste incineration are studied. ? More PAHs were found in fly ash than that in bottom ash. ? The highest proportion of PAHs consisted of the seven most carcinogenic ones. ? Increase of free oxygen molecule and burning temperature promote PAHs degradation. ? There is a moderate positive correlation between total PCDD/Fs and total PAHs. - Abstract: After the deadly earthquake on May 12, 2008 in Wenchuan county of China, several different incineration approaches were used for medical waste disposal. This paper investigates the generation properties of polycyclic aromatic hydrocarbons (PAHs) during the incineration. Samples were collected from the bottom ash in an open burning slash site, surface soil at the open burning site, bottom ash from a simple incinerator, bottom ash generated from the municipal solid waste (MSW) incinerator used for medical waste disposal, and bottom ash and fly ash from an incinerator exclusively used for medical waste. The species of PAHs were analyzed, and the toxicity equivalency quantities (TEQs) of samples calculated. Analysis results indicate that the content of total PAHs in fly ash was 1.8 × 10{sup 3} times higher than that in bottom ash, and that the strongly carcinogenic PAHs with four or more rings accumulated sensitively in fly ash. The test results of samples gathered from open burning site demonstrate that Acenaphthylene (ACY), Acenaphthene (ACE), Fluorene (FLU), Phenanthrene (PHE), Anthracene (ANT) and other PAHs were inclined to migrate into surrounding environment along air and surface watershed corridors, while 4- to 6-ring PAHs accumulated more likely in soil. Being consistent with other studies, it has also been confirmed that increases in both free oxygen molecules and combustion temperatures could promote the decomposition of polycyclic PAHs. In addition, without the influence of combustion conditions, there is a positive correlation between total PCDD/Fs and total PAHs, although no such relationship has been found for TEQ.

Chen, Ying, E-mail: echochen327@163.com [School of Environment, Tsinghua University, Beijing 100084 (China); National Center of Solid Waste Management, Ministry of Environmental Protection, Beijing 100029 (China); Zhao, Rongzhi [Civil and Environmental Engineering School, University of Science and Technology Beijing, Beijing 100083 (China); Xue, Jun [National Center of Solid Waste Management, Ministry of Environmental Protection, Beijing 100029 (China); Li, Jinhui, E-mail: jinhui@tsinghua.edu.cn [State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084 (China)

2013-05-15

369

Lack of PAH emission toward low-mass embedded young stellar objects  

E-print Network

PAHs have been detected toward molecular clouds and some young stars with disks, but have not yet been associated with embedded young stars. We present a sensitive mid-IR spectroscopic survey of PAH features toward a sample of low-mass embedded YSOs. The aim is to put constraints on the PAH abundance in the embedded phase of star formation using radiative transfer modeling. VLT-ISAAC L-band spectra for 39 sources and Spitzer IRS spectra for 53 sources are presented. Line intensities are compared to recent surveys of Herbig Ae/Be and T Tauri stars. The radiative transfer codes RADMC and RADICAL are used to model the PAH emission from embedded YSOs consisting of a PMS star with a circumstellar disk embedded in an envelope. The dependence of the PAH feature on PAH abundance, stellar radiation field, inclination and the extinction by the surrounding envelope is studied. The 3.3 micron PAH feature is undetected for the majority of the sample (97%), with typical upper limits of 5E-16 W/m^2. Compact 11.2 micron PAH emission is seen directly towards 1 out of the 53 Spitzer Short-High spectra, for a source that is borderline embedded. For all 12 sources with both VLT and Spitzer spectra, no PAH features are detected in either. In total, PAH features are detected toward at most 1 out of 63 (candidate) embedded protostars (<~ 2%), even lower than observed for class II T Tauri stars with disks (11-14%). Assuming typical class I stellar and envelope parameters, the absence of PAHs emission is most likely explained by the absence of emitting carriers through a PAH abundance at least an order of magnitude lower than in molecular clouds but similar to that found in disks. Thus, most PAHs likely enter the protoplanetary disks frozen out in icy layers on dust grains and/or in coagulated form.

V. C. Geers; E. F. van Dishoeck; K. M. Pontoppidan; F. Lahuis; A. Crapsi; C. P. Dullemond; G. A. Blake

2008-12-18

370

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

371

Influence of biotransformation on trophic transfer of the PAH, fluoranthene.  

PubMed

The persistence of polycyclic aromatic hydrocarbons (PAHs) in marine sediments may be influenced by benthic invertebrate bioturbation. Through processes such as deposit-feeding and enhancement of microbial metabolic activity PAHs may be remobilized from the sediment compartment, and either transferred to organisms at higher trophic levels or to the overlying water column, both processes inevitably changing the bioavailability of the PAH. Accumulation of contaminants from one level in the food chain to the next depends on feeding rate and assimilation efficiency, two factors that basically vary with food quality and contaminant type. Though it is generally believed that pre-consumptive biotransformation will reduce bioavailability due to the more polar nature of the metabolites compared to the unchanged parent compound, theoretically the decrease in lipophilicity will increase the sediment/food desorption rate in the intestine, and some metabolites will still be lipophilic enough to be absorbed by passive diffusion. We examined the trophic transfer of the PAH, fluoranthene from two closely related polychaete species (i.e., Capitella sp. I and Capitella sp. S), differing in their biotransformation ability, to the predatory polychaete, Nereis virens. We found that N. virens fed the biotransforming species, Capitella sp. I, accumulated significantly more Flu equivalents compared to worms fed Capitella sp. S, which have a very limited biotransformation ability. The dose-specific increase in N. virens intestinal Flu concentration was approximately twice as high in worms fed Capitella sp. I (equation: gut content=7.3 x dose-3.9) compared to worms fed Capitella sp. S (equation: gut content=3.2 x dose+0.6). In addition, we measured DNA damage, using the comet assay, in N. virens intestinal cells after feeding with the two prey species. We did not detect DNA damage above 'background' levels for worms fed either of the two Capitella species, possibly due to relatively low intestinal Flu concentrations in N. virens. Our results indicate that accumulation of PAHs by infaunal organisms may play an important role in the transfer of this type of contaminant to higher trophic levels. Moreover, we observed differences in transfer potential between parent compounds and their respective metabolites, which may influence the fate of these compounds in marine ecosystems. However, from the present study it cannot be concluded whether differences in biotransformation ability among prey species can lead to different effects in their predators. PMID:17084915

Palmqvist, Annemette; Rasmussen, Lene Juel; Forbes, Valery E

2006-12-01

372

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

2014-12-01

373

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

374

PAH Concentrations Decline Following 2006 Ban on Coal-Tar-Based Pavement Sealants in Austin, Texas  

NASA Astrophysics Data System (ADS)

Recent studies have concluded that coal-tar-based pavement sealants (CT sealants) are a major source of polycyclic aromatic hydrocarbons (PAHs) in non-industrial urban settings in the United States. In 2006, Austin, TX, became the first jurisdiction in the U.S. to ban the use of CT sealants. We evaluated PAH concentrations following the ban by analyzing sediment cores collected from Lady Bird Lake in 2012; Lady Bird Lake impounds the Colorado River in central Austin and receives runoff from much of the greater Austin area. The mean sum concentration of the 16 U.S. Environmental Protection Agency Priority Pollutant PAHs (?PAH16) in one of two 2012 sediment cores analyzed for PAHs declined 75% from before 2006 (mean of 4 samples=8,090 ?g kg-1) to 2012 (mean of 2 samples=2,030 ?g kg-1), reversing a 40-year (1959-1999) upward trend in PAH concentrations that was previously documented. The downward trend in PAH concentrations in the seven uppermost 1 cm sampling intervals in the first 2012 core was statistically significant (r=0.93, p-value=0.002). Post-2008 PAH trends in the second 2012 core were similar (significant downward trend in the six uppermost 1 cm sampling intervals and mean 2012 ?PAH16 of 2,390 ?g kg-1); however, pre-2007 sediment did not appear to have been preserved in this core likely because of the effects of flooding on sediment deposition and mixing at this site--the largest flood on the Colorado River in Austin in 20 years was in 2007. On the basis of a comparison of lake-sediment PAH profiles to 22 PAH source profiles, the PAH loading to lake sediment continues to be dominated by CT sealants. The continued dominance of proportional PAH loading by CT sealants in spite of decreased concentrations since 2006 might be because legacy CT sealant and contaminated soils and sediments continue to yield PAHs to runoff. A previous study using source-receptor modeling concluded that CT sealants were the largest PAH source to 40 urban lakes studied in the U.S. (including Lady Bird Lake) and were the primary cause of increasing PAH trends in recent decades. The results presented here are the first direct evidence that removing this source can lead to a substantial reduction in PAH concentrations in receiving water bodies. CT sealants are sprayed or painted on asphalt parking lots and driveways. The sealant abrades into fine particles that can be washed into streams and lakes and tracked into homes.

Van Metre, P. C.; Mahler, B. J.

2013-12-01

375

Genomic structure of the Aeromonas bacteriophage pAh6-C and its comparative genomic analysis.  

PubMed

pAh6-C is a virulent bacteriophage (phage), isolated from a river in Korea, that infects a multiple-antibiotic-resistant A. hydrophila strain, JUNAH. The double-stranded DNA genome of pAh6-C is composed of 53,744 bp with a G + C content of 52.83 %. The genome encodes 86 putative ORFs, four putative promoters, and seven transcriptional terminator regions. Genome sequence analysis of pAh6-C and comparative analysis with the homologous Shewanella phage Spp001 revealed that there is a high degree of similarity between pAh6-C and Spp001 in 50 of the 86 ORFs of pAh6-C. The results of this investigation indicate that pAh6-C is closely related to Spp001, especially in the genes coding for proteins involved in DNA metabolism. PMID:25189428

Jun, Jin Woo; Kim, Hyoun Joong; Yun, Sae Kil; Chai, Ji Young; Park, Se Chang

2015-02-01

376

Spatial distribution and source apportionment of PAHs in surficial sediments of the Yangtze Estuary, China.  

PubMed

Spatial distribution and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in the surface sediments of the Yangtze Estuary, especially the North Branch, have been fully investigated. PAH concentrations increased with the descending distance from the inner estuary to the adjacent sea, and varied significantly in various estuarine regions. Water currents (e.g., river runoff and ocean current) greatly affected the distribution pattern. In addition, ambient sewage and traffic also contributed to the PAH pollution in the estuary. In the adjacent sea, PAH values along the -20m isobath were higher than those along the -10m isobath due to the "marginal filter" phenomenon formed by different water currents. In most sites, PAHs had poor correlations with sediment size, but had positive correlations with total organic carbon. Based on the qualitative and quantitative analysis results, PAH sources were proved to be mainly from a mixture of petroleum combustion, biomass, and coal combustion. PMID:22245436

Li, Baohua; Feng, Chenghong; Li, Xue; Chen, Yaxin; Niu, Junfeng; Shen, Zhenyao

2012-03-01

377