Polycyclic Aromatic Hydrocarbons In Medium Research Articles

PAHs in medium and high rank Bulgarian coals – insights from aromatic indices

The study presents analyses of aromatic components in bitumen extracts from Bulgarian medium and high rank coals. Bulk samples from Balkan, Ro = 0.96%, Dobroudzha, Ro = 1.13%, and Svoge, Ro = 5.20% coal-bearing provinces, were considered. After extensive chromatographic separation and GC-MS study of the aromatic fractions, our attention was focused on polycyclic aromatic hydrocarbons (PAHs) compositions. Aromatic indices, based on quantification of individual compounds, revealed that: (i) the highest amounts of PAHs were present in Balkan and Dobroudzha samples, 219–365 μg/g TOC, and dropped to 3.5 μg/g TOC at Svoge sample; (ii) the alkylated naphthalenes and phenantrenes prevalence confirmed published data; (iii) the relationship between aromatic indices vs. Ro, % is in agreement with the previously obtained results, indicating their decrease with thermal maturity. For some indices only weak correlation was obtained, suggesting that PAH concentrations are not solely affected by coal rank, but also by environmental conditions and vegetation.

Biochar and fungi as bioretention amendments for bacteria and PAH removal from stormwater

Bioretention has been widely used to mitigate hydrologic impacts of stormwater runoff and is increasingly being relied upon to treat chemical and biological pollutants transported by stormwater. Despite this reliance, we still lack an understanding of treatment performance for certain organic and biological contaminants which may interact with biotic and abiotic components of bioretention systems. We evaluated the treatment of fecal indicator bacteria (FIB) and polycyclic aromatic hydrocarbons (PAHs) in stormwater runoff by bioretention. We compared treatment performance by Washington's standard bioretention mix of 60% sand: 40% compost (by volume), and by three other mixtures amended with biochar, fungi (Stropharia rugosoannulata), or both. All bioretention columns were conditioned with clean water and then dosed with collected roadway runoff at a rate equivalent to a 6 month, 24 h storm in this region during 8 events over a 14-month period. Effluents for each column were analyzed for 23 PAHs, Escherichia coli, fecal coliform, dissolved organic carbon (DOC), and total suspended solids (TSS). The fate and transport of PAHs within the bioretention columns was tracked by measuring soil PAHs in media cores taken from the columns. ΣPAH were almost completely removed by all treatments across all storms, with removal rates ranging from 97 to 100% for 94 out of 96 samples. Compost appeared to be a source of PAHs in bioretention media, as biochar-amended media initially contained half the ΣPAHs as treatments with the standard 60:40 sand:compost mixture. We observed a net loss of ΣPAHs (19–73%) in bioretention media across the study, which could not be explained by PAHs in the effluent, suggesting that bioremediation by microbes and/or plants attenuated media PAHs. E. coli and fecal coliform were exported in the first dosing event, but all columns achieved some treatment in subsequent dosing events. Overall, these findings suggest that PAHs in stormwater can be remediated with bioretention, are unlikely to accumulate in bioretention media, and that biochar amendments can improve the treatment of E. coli.

Polycyclic Aromatic Hydrocarbons in the Snow Cover of Moscow (Case Study of the RUDN University Campus)

The major objective of this study are polycyclic aromatic hydrocarbons (PAHs) in the snow cover of the RUDN-University campus. The campus is located in the south-west of Moscow, in a relatively clean zone of the city. However, the atmospheric pollution introduces a significant amount of the contaminants into this area, including PAHs. The area is affected by several anthropogenic sources, and the major highways are the largest contributor of air pollution. The presence of PAH in the snow cover is also due to these sources. The paper investigates interrelation of pollution character and transport activity mode. The pyrogenic genesis of pollution was confirmed using indicator ratios of PAH isomers. This method can demonstrate significant errors; therefore, the study investigates the informative value of the indicators. Implementation of a complex of ratios confirmed pyrogenic pollution. Due to the complexity and originality of the local conditions of scattered pollution the profiles of the prevalence of PAHs in the snow cover of the campus practically do not correspond to theoretical models. The study revealed dominant pollutants, i.e. Flu, Py, Phen, BbFlu, in contrast to earlier findings, traditionally used to describe the distribution of PAHs in media (soil, snow etc.). It draws on the specificity of migration and accumulation of PAHs, which may be due to the phase-structural transitions in the “snow-water” system, occurring during thaws and cold spells, and the specificity of pyrogenic pollution

Characterization of Petroleum Hydrocarbon Decomposing Fungi Isolated from Mangrove Rhizosphere

The research was done to obtain the isolates of soil borne fungi isolated from mangrove rhizosphere which were capable of degrading petroleum hydrocarbon compounds. The soil samples were collected from South Sumatra mangrove forest which was contaminated by petroleum. The isolates obtained were selected based on their ability to survive, to grow and to degrade polycyclic aromatic hydrocarbons in medium containing petroleum residue. There were 3 isolates of soil borne hydrocarbonoclastic fungi which were able to degrade petroleum in vitro. The 3 isolates were identified as Aspergillus fumigates, A. parasiticus, and Chrysonilia sitophila. C. sitophila was the best isolate to decrease total petroleum hydrocarbon (TPH) from medium containing 5-20% petroleum residue.Keywords: Hydrocarbonoclastic fungi, hydrocarbon compounds, mangrove rhizosphere

Water Table Fluctuation in Tidal Lowland for Developing Agricultural Water Management Strategies

The research was done to obtain the isolates of soil borne fungi isolated from mangrove rhizosphere which were capable of degrading petroleum hydrocarbon compounds. The soil samples were collected from South Sumatra mangrove forest which was contaminated by petroleum. The isolates obtained were selected based on their ability to survive, to grow and to degrade polycyclic aromatic hydrocarbons in medium containing petroleum residue. There were 3 isolates of soil borne hydrocarbonoclastic fungi which were able to degrade petroleum in vitro. The 3 isolates were identified as Aspergillus fumigates, A. parasiticus, and Chrysonilia sitophila. C. sitophila was the best isolate to decrease total petroleum hydrocarbon (TPH) from medium containing 5-20% petroleum residue. Keywords: Hydrocarbonoclastic fungi, hydrocarbon compounds, mangrove rhizosphere

Effects of a pre-incubation period on the photoinduced toxicity of polycyclic aromatic hydrocarbons to the luminescent bacterium Vibrio fischeri.

Irradiation of polycyclic aromatic hydrocarbons (PAHs) in aqueous solution with simulated solar radiation (SSR; a light source with a visible light: UV-A:UV-B ratio similar to that of sunlight) can greatly enhance their toxicity. Two microbial toxicity tests with Vibrio fischeri were used to investigate the effect of composition of the growth medium and pre-incubation on the photoinduced toxicity of PAHs. The assays were a short-term test (15 min) and long-term test (18 h). Both assays were carried out in SSR and darkness to examine for photoinduced toxicity of PAHs. For the short-term toxicity assay, inhibition of bacterial luminescence was measured. For the long-term toxicity assay, both inhibition of bacterial luminescence and inhibition of growth were recorded. To broaden this test, V. fischeri cells were pre-incubated with PAHs in medium without a carbon source (minimal medium) for 8 h to facilitate assimilation and photooxidation of the contaminants, and to prevent bacterial growth at the outset of the assay. V. fischeri was more sensitive in minimal medium than in complex medium in both the short- and long-term toxicity assays. Moreover, in the long-term assay, SSR greatly increased toxicity, especially if there was a pre-incubation period in minimal medium. This indicates that both assimilation and photooxidation of PAHs are important to their toxicity to V. fischeri.

Biocatalytic oxidation of polycyclic aromatic hydrocarbons in media containing organic solvents

Lignin peroxidase, cytochrome c and haemoglobin were tested for oxidation of polycyclic aromatic hydrocarbon (PAH) in the presence of hydrogen peroxide. The reaction mixture Contained water-miscible organic solvents in order to reduce the mass transfer limitation of hydrophobic substrates. The reaction products from all three haemoproteins were mainly quinones, suggesting the same oxidation mechanism for the three biocatalysts. The haeme prosthetic group must have located in a protein environment for it to catalyze these reactions, and only certain types of protein environment are able to induce this type of haemebased catalytic activity. The solvent hydrophobicity is a factor affecting the biocatalysis in organic media. Substrate partitioning between the active site (haeme) and the bulk solvent is the main factor of the biocatalytic behaviour in organic solvent mixtures. Site-directed mutagenesis of yeast cytochrome c significantly altered the kinetic behaviour of the protein. The Gly82;Thr 102 variant was 10 times more active and showed a catalytic efficiency 10-fold greater than the wild-type iso-1-cytochrome c. These results suggest that it is possible to design a new biocatalyst for environmental purposes.

Molecular shape recognition of polycyclic aromatic hydrocarbons with various alkyl diphenyl bonded phases in microcolumn liquid chromatography

The basic retention behaviors of polycyclic aromatic hydrocarbons (PAHs) with various novel alkyl diphenyl bonded phases have been examined using microcolumn liquid chromatography The retention behaviors of PAHs with these phases have been compared to those with n-alkyl bonded phases which have the same carbon numbers but methyl side groups instead of phenyl groups. Three different alkyl chain lengths for bothn-alkyl dimenthyl andn-alkyl diphenyl bonded phases such as C4, C8 and C 18 were used in this study. It was found that thesen-alkyl diphenyl phases have a non-planarity recognition capability for small and medium PAHs. It appears that this capability increases as the alkyl chain length of the bonded phases decreases. The short or medium alkyl chain length diphenyl bonded phases retained non-planar solutes better than the planar solutes. This trend is completely opposite to that with dimethyl analogs. This unique retention behavior is believed to be caused by strong molecular-molecular interaction between non-planar solutes and the two phenyl groups in those diphenyl stationary phases.

Biocatalytic oxidation of polycyclic aromatic hydrocarbons in media containing organic solvents

Lignin peroxidase, cytochrome c and haemoglobin were tested for oxidation of polycyclic aromatic hydrocarbon (PAH) in the presence of hydrogen peroxide. The reaction mixture Contained water-miscible organic solvents in order to reduce the mass transfer limitation of hydrophobic substrates. The reaction products from all three haemoproteins were mainly quinones, suggesting the same oxidation mechanism for the three biocatalysts. The haeme prosthetic group must have located in a protein environment for it to catalyze these reactions, and only certain types of protein environment are able to induce this type of haemebased catalytic activity. The solvent hydrophobicity is a factor affecting the biocatalysis in organic media. Substrate partitioning between the active site (haeme) and the bulk solvent is the main factor of the biocatalytic behaviour in organic solvent mixtures. Site-directed mutagenesis of yeast cytochrome c significantly altered the kinetic behaviour of the protein. The Gly82;Thr 102 variant was 10 times more active and showed a catalytic efficiency 10-fold greater than the wild-type iso-1-cytochrome c. These results suggest that it is possible to design a new biocatalyst for environmental purposes.

The spectral energy distribution of star-forming regions

view Abstract Citations (29) References (113) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Spectral Energy Distribution of Star-forming Regions Siebenmorgen, Ralf Abstract We present exact solutions of the radiative transfer problem for clouds containing quantum-heated dust particles, with attention to dust destruction as appropriate for modeling star-forming regions. The dust model by Siebenmorgen and Kruegel (1993) is compared with models containing only large grains heated under steady state conditions. We demonstrate that both models can be distinguished by studying the surface brightness morphology of objects at midinfrared wavelengths. The emission bands of polycyclic aromatic hydrocarbons in media with high optical depth is studied and the multicomponent grain emission and temperature structures inside opaque clouds is discussed. We present excellent fits of a sample of well-known star-forming regions by calculating beam-matched spectral energy distributions. The current problems of modeling the infrared emission from star-forming regions are summarized. We suggest that a scenario of disklike structures embedded in the circumstellar dust envelope might better match the observations. The disk grains should be large and of inhomogeneous structure. The grain absorption cross sections of fluffy grains are calculated by using the Maxwell-Garnett mixing rule. We find that compositional inhomogeneities of dust grains will affect the silicate bands and increase the absorptivity at far-infrared and submillimeter wavelengths. Publication: The Astrophysical Journal Pub Date: May 1993 DOI: 10.1086/172581 Bibcode: 1993ApJ...408..218S Keywords: Astronomical Models; Cosmic Dust; Spectral Energy Distribution; Star Formation; Stellar Envelopes; Infrared Astronomy; Interstellar Extinction; Radiative Transfer; Astrophysics; INFRARED: STARS; ISM: DUST; EXTINCTION; RADIATIVE TRANSFER; STARS: FORMATION full text sources ADS | data products SIMBAD (13)