Quantification and source identification of atmospheric particulate polycyclic aromatic hydrocarbons and their dry deposition fluxes at three sites in Salvador Basin, Brazil, impacted by mobile and stationary sources

The present work has aimed to determine the 16 US EPA priority PAH atmospheric particulate matter levels present in three sites around Salvador, Bahia: (i) Lapa bus station, strongly impacted by heavy-duty diesel vehicles; (ii) Aratu harbor, impacted by an intense movement of goods, and (iii) Bananeira village on Maré Island, a non vehicle-influenced site with activities such as handcraft work and fisheries. Results indicated that BbF (0.130-6.85 ng m-3) is the PAH with highest concentration in samples from Aratu harbor and Bananeira and CRY (0.075-6.85 ng m-3) presented higher concentrations at Lapa station. PAH sources from studied sites were mainly of anthropogenic origin such as gasoline-fueled light-duty vehicles and diesel-fueled heavy-duty vehicles, discharges in the port, diesel burning from ships, dust ressuspension, indoor soot from cooking, and coal and wood combustion for energy production.

Electrochemical and photocatalytic reactions of polycyclic aromatic hydrocarbons investigated by raman spectroscopy

This paper presents the study of photochemical behavior of polycyclic aromatic hydrocarbons (PAHs), potential pollutants in secondary reactions in aerosols, through Raman spectroscopy compared with its electrochemical behavior. The PAHs studied include pyrene, anthracene, phenanthrene and fluorene. These were adsorbed onto TiO2 and irradiated with ultraviolet light (254 nm). Their electrochemical oxidation was studied by in situ Surface-enhanced Raman Scattering (SERS) and led to the formation of carbonyl-containing products. Oxidized intermediates bearing the C=O group were also formed during photodegradation. The joint analysis of the photodegradation data with those produced by electrochemical means - using spectroscopic techniques for the identification and characterization of the products - revealed the formation of identical products for anthracene, but not for pyrene. A reasonable explanation for this difference in results is that photochemical and electrochemical oxidation reactions proceed via different mechanisms. While photocatalytic degradation over TiO2 is initiated by hydroxyl radicals, electrochemical oxidation is initiated by the direct electron transfer from adsorbed PAH to the electrode, generating PAH cation radicals that undergo subsequent reactions.

Emission of polycyclic aromatic hydrocarbons from gasohol and ethanol vehicles

The exhaust emission of the polycyclic aromatic hydrocarbons (PAHs) considered toxic to human health were investigated on two spark ignition light duty vehicles, one being gasohol (Gasohol, in Brazil, is the generic denomination for mixtures of pure gasoline plus 20-25% of anhydrous ethyl alcohol fuel (AEAF).)-fuelled and the other a flexible-fuel vehicle fuelled with hydrated ethanol. The influence of fuel type and quality, aged lubricant oil type and use of fuel additives on the formation of these compounds was tested using standardized tests identical to US FTP-75 cycle. PAH sampling and chemical analysis followed the basic recommendations of method TO-13 (United States. Environmental Protection Agency, 1999. Compendium Method TO-13A - Determination of polycyclic Aromatic hydrocarbons (PAH) in Ambient Air Using Gas Chromatography/Mass Spectrometry (CG/MS). Center for environmental research information, Cincinnati, p. 78), with the necessary modification for this particular application. Results showed that the total PAH emission factor varied from 41.9 mu g km(-1) to 612 mu g km(-1) in the gasohol vehicle, and from 11.7 mu g km(-1) to 27.4 mu g km(-1) in the ethanol-fuelled vehicle, a significant difference in favor of the ethanol vehicle. Generally, emission of light molecular weight PAHs was predominant, while high molecular weights PAHs were not detected. In terms of benzo(a)pyrene toxicity equivalence, emission factors varied from 0.00984 mu g TEQ km(-1) to 4.61 mu g TEQ km(-1) for the gasohol vehicle and from 0.0117 mu g TEQ km(-1) to 0.0218 mu g TEQ km(-1) in the ethanol vehicle. For the gasohol vehicle, results showed that the use of fuel additive causes a significant increase in the emission of naphthalene and phenanthrene at a confidence level of 90% or higher; the use of rubber solvent on gasohol showed a reduction in the emission of naphthalene and phenanthrene at the same confidence level; the use of synthetic oil instead of mineral oil also contributed significantly to a decrease in the emission of naphthalene and fluorene. In relation to the ethanol vehicle, the same factors were tested and showed no statistically significant influence on PAH emission. (c) 2008 Elsevier Ltd. All rights reserved.

On the catalytic hydrogenation of polycyclic aromatic hydrocarbons into less toxic compounds by a facile recoverable catalyst

Here we present the catalytic hydrogenation of polycyclic aromatic hydrocarbons (PAHs) to less toxic mixtures of saturated and partial unsaturated polycyclic hydrocarbons under mild reaction conditions using a magnetically recoverable rhodium catalyst and molecular hydrogen as the exclusive H source. The catalyst is easily recovered after each reaction by placing a permanent magnet on the reactor wall and it can be reused in successive runs without any significant loss of catalytic activity. As an example, anthracene was totally converted into the saturated polycyclic hydrocarbon form (ca. 60%) and the partially hydrogenated form, 1,2,3,4,5,6,7,8-octahydroanthracene (ca. 40%). The catalyst operates in a broad range of temperature and H(2) pressure in both organic and aqueous/organic solutions of anthracene and it also exhibits significant activity at low substrate concentrations (20 ppm). This can be an efficient recycling process for hydrogenation of PAHs present in contaminated fluid waste streams. (C) 2009 Elsevier B.V. All rights reserved.

Improving the Fluorescence Detectability of Polycyclic Aromatic Hydrocarbons for Evaluation of Workplace Environments of Cement Industries Processing Organic Residues

The burning of organic residues and wastes in furnaces of cement industries has been an attractive and lucrative approach to eliminate stocks of these pollutants. There is a potential risk for producing PAH in the workplace of industries burning organic wastes, so that highly sensitive analytical methods are needed for monitoring the air quality of these environments. An official method for determination of PAH is based on liquid chromatography with fluorescence detection at fixed excitation and emission wavelengths. We demonstrate that a suitable choice of these wavelengths, which are changed during the chromatographic run, significantly improves the detectability of PAH in atmosphere and particulate matter collected in cement industries.

Biodegradation of polyurethane derived from castor oil

The aim of this research was to study the biodegradation of a polymer derived from castor oil, which is a renewable, natural material that is a practical alternative for the replacement of traditional polyurethane foams. Due to its molecular structure, which contains polyester segments derived from vegetable oil, the polymeric surface is susceptible to microorganism attack. This study tested the biological degrading agent that was in contact with the microorganisms resulting from microbiological grease degrading agents, when foam was inoculated. Solid-media agar-plate tests were conducted for their potential to evaluate the biodegradation of polymeric particles by specific strains of microorganisms during 216 hours. The growth rate was defined. This technique provides a way of distinguishing the degradation abilities of microorganisms from the degradability of materials.

Variations on a theme: diversification of cuticular hydrocarbons in a clade of cactophilic Drosophila

Background: We characterized variation and chemical composition of epicuticular hydrocarbons (CHCs) in the seven species of the Drosophila buzzatii cluster with gas chromatography/mass spectrometry. Despite the critical role of CHCs in providing resistance to desiccation and involvement in communication, such as courtship behavior, mating, and aggregation, few studies have investigated how CHC profiles evolve within and between species in a phylogenetic context. We analyzed quantitative differences in CHC profiles in populations of the D. buzzatii species cluster in order to assess the concordance of CHC differentiation with species divergence. Results: Thirty-six CHC components were scored in single fly extracts with carbon chain lengths ranging from C(29) to C(39), including methyl-branched alkanes, n alkenes, and alkadienes. Multivariate analysis of variance revealed that CHC amounts were significantly different among all species and canonical discriminant function (CDF) analysis resolved all species into distinct, non-overlapping groups. Significant intraspecific variation was found in different populations of D. serido suggesting that this taxon is comprised of at least two species. We summarized CHC variation using CDF analysis and mapped the first five CHC canonical variates (CVs) onto an independently derived period (per) gene + chromosome inversion + mtDNA COI gene for each sex. We found that the COI sequences were not phylogenetically informative due to introgression between some species, so only per + inversion data were used. Positive phylogenetic signal was observed mainly for CV1 when parsimony methods and the test for serial independence (TFSI) were used. These results changed when no outgroup species were included in the analysis and phylogenetic signal was then observed for female CV3 and/or CV4 and male CV4 and CV5. Finally, removal of divergent populations of D. serido significantly increased the amount of phylogenetic signal as up to four out of five CVs then displayed positive phylogenetic signal. Conclusions: CHCs were conserved among species while quantitative differences in CHC profiles between populations and species were statistically significant. Most CHCs were species-, population-, and sex-specific. Mapping CHCs onto an independently derived phylogeny revealed that a significant portion of CHC variation was explained by species' systematic affinities indicating phylogenetic conservatism in the evolution of these hydrocarbon arrays, presumptive waterproofing compounds and courtship signals as in many other drosophilid species.

Effect of terbium(III) on the binding of aromatic guests with sodium taurocholate aggregates

The effect of binding Tb(3+) to sodium taurocholate aggregates containing polyaromatic hydrocarbon guests was examined using pyrene and 1-ethylnaphthalene as guests that bind to the primary aggregate, and 1-naphthyl-1-ethanol as a secondary aggregate guest. Time-resolved fluorescence quenching studies were used to study the binding site properties, while laser flash photolysis quenching studies provided information on the dynamics of the guest-aggregate system. Both the primary and secondary aggregate binding sites became more compact in the presence of bound Tb(3+), while only the primary aggregate became more accessible to anionic molecules. The binding dynamics for the guest-primary aggregate system became faster when Tb(3+) was bound to the aggregate. In contrast, for the guest-secondary aggregate the presence of Tb(3+) resulted in a small decrease in the dissociation rate constant. The influence of bound Tb(3+) on the primary and secondary bile salt aggregates is significantly different, which affects how these aggregates can be used as supramolecular host systems to modify guest reactivity.

Relevance of extractives and wood transformation products on the biodegradation of Pinus taeda by Ceriporiopsis subvermispora

Ceriporiopsis subvermispora is a promising white-rot fungus for biopulping. However, the underlying biochemistry involved in lignin removal and insignificant cellulose degradation by this species is not completely understood. This paper addresses this topic focusing on the involvement of ethanol-soluble extractives and wood transformation products in the biodegradation process. Cultures containing ethanol-extracted or in natura wood chips presented similar levels of extracellular enzymes and degradation of wood components. Fe3+-reducing compounds present in undecayed Pinus taeda were rapidly diminished by fungal degradation. Lignin-degradation products released during biodegradation restored part of the Fe3+-reducing activity. However, Fe3+ reduction was ineffective in presence of 0.5 mM oxalate at pH 4.5. Fungal consumption of Fe3+-reducing compounds and secretion of oxalic acid minimized the significance of Fenton`s reaction in the initial stages of wood biotreatment. This would explain limited polysaccharide degradation by the fungus that also lacks a complete set of hydrolytic enzymes. Scientific relevance of the paper: Ceriporiopsis subvermispora is a white-rot fungus suitable for biopulping processes because it degrades lignin selectively and causes significant structural changes on the wood components during the earlier decay stages. However, the intricate mechanism to explain lignin transformation and insignificant cellulose degradation by this species remains poorly understood. Some recent evidences pointed out for lipid peroxidation reactions as all initiating process explaining lignin degradation. On the other hand, alkylitaconic acids produced by the fungus via transformations of fatty acids occurring in wood showed to prevent polysaccharide degradation in Fenton reactions. In this context, one may conclude that the involvement of native wood substances or their transformation products in the overall wood biodegradation process induced by C subvermispora is still a matter of discussion. While free and esterified fatty acids present in wood extractives may be involved in the biosynthesis of alkylitaconic acids and in lipid peroxidation reactions, some extractives and lignin degradation products can reduce Fe3+, providing Fe2+ species needed to form OH radical via Fenton`s reaction. The present study focuses on this topic by evaluating the relevance of ethanol-soluble extractives and wood transformation products on the biodegradation of P. taeda by C subvermispora. For this, solid-state cultures containing ethanol-extracted and in natura wood chips were evaluated in details for up to 4 weeks. (C) 2007 Elsevier Ltd. All rights reserved.

NMR study of slow motions of HDA hydrocarbons chains inside lamellar structures

Measurements of H-1 and C-13 Nuclear Magnetic Resonance (NMR) for the nano-composite materials formed by the intercalation of hexadecylamine (HDA) in metal oxides (TiO2, V2O5 and MoO3), are reported. The H-1 NMR spin-lattice relaxation in the rotating frame was described by using the spectral density due to Davidson and Cole, which incorporates a distribution of correlation times characterized by a width parameter epsilon. The fitting of the data was obtained for epsilon = 0.74, indicating that the correlation times are distributed over a narrow range in this system. High-resolution C-13 NMR techniques were used to resolve the NMR lines of middle-chain methylene groups in the spectra and variable contact time cross-polarization {H-1-}C-13 experiments were employed to analyze the reorientation dynamics of the CH3 and CH2 groups in the HDA chains.

Improving the enantioselective bioreduction of aromatic ketones mediated by Aspergillus terreus and Rhizopus oryzae: the role of glycerol as a co-solvent

The improvement of the enzymatic performance of Aspergillus terreus and Rhizopus oryzae in enantioselective bioreductions by using glycerol as a co-solvent has been studied. In the most of the bioreductions, glycerol has demonstrated its potential for improved conversions (up to >99%) and enantioselectivities (up to >99%) when compared to reactions in aqueous or other aqueous-organic media (THF, diethyl ether, toluene, DMSO and acetonitrile). Moreover, high isolated yields of the desired chiral alcohols have been obtained on a preparative scale showing the great potential of this green solvent in biocatalysis. (C) 2009 Elsevier Ltd. All rights reserved.

Crystallization and preliminary X-ray diffraction analysis of recombinant chlorocatechol 1,2-dioxygenase from Pseudomonas putida

Chlorocatechol 1,2-dioxygenase from the Gram-negative bacterium Pseudomonas putida (Pp 1,2-CCD) is considered to be an important biotechnological tool owing to its ability to process a broad spectrum of organic pollutants. In the current work, the crystallization, crystallographic characterization and phasing of the recombinant Pp 1,2-CCD enzyme are described. Reddish-brown crystals were obtained in the presence of polyethylene glycol and magnesium acetate by utilizing the vapour-diffusion technique in sitting drops. Crystal dehydration was the key step in obtaining data sets, which were collected on the D03B-MX2 beamline at the CNPEM/MCT - LNLS using a MAR CCD detector. Pp 1,2-CCD crystals belonged to space group P6(1)22 and the crystallographic structure of Pp 1,2-CCD has been solved by the MR-SAD technique using Fe atoms as scattering centres and the coordinates of 3-chlorocatechol 1,2-dioxygenase from Rhodococcus opacus (PDB entry 2boy) as the search model. The initial model, which contains three molecules in the asymmetric unit, has been refined to 3.4 A resolution.

Bioremediation of gasoline-contaminated groundwater in a pilot-scale packed-bed anaerobic reactor

This work reports on the anaerobic treatment of gasoline-contaminated groundwater in a pilot-scale horizontal-flow anaerobic immobilized biomass reactor inoculated with a methanogenic consortium. BTEX removal rates varied from 59 to 80%, with a COD removal efficiency of 95% during the 70 days of in situ trial. BTEX removal was presumably carried out by microbial syntrophic interactions, and at the observed concentrations, the interactions among the aromatic compounds may have enhanced overall biodegradation rates by allowing microbial growth instead of co-inhibiting biodegradation. There is enough evidence to support the conclusion that the pilot-scale reactor responded similarly to the lab-scale experiments previously reported for this design. (C) 2009 Elsevier Ltd. All rights reserved.

Characterization of the Phenol Monooxygenase Gene from Chromobacterium violaceum: Potential Use for Phenol Biodegradation

In this work, the biodegradation mechanism of phenol and sub products (such as catechol and hydroquinone) in Chromobacterium violaceum was investigated by cloning and molecular characterization of a phenol monooxygenase gene in Escherichia coli. This gene (Cvmp) is very similar (74 and 59% of similarity and identity, respectively) to the ortholog from Ralstonia eutropha, bacteria capable of utilizing phenol as the sole carbon source. The phenol biodegradation ability of E. coli recombinant strains was tested by cell-growth in a minimal medium containing phenol as the sole source of carbon and release of intermediary metabolites (catechol and hydroquinone). Interestingly, during the growth of these strains on phenol, catechol, and hydroquinone accumulated transiently in the medium. These metabolites were further analyzed by HPLC. These results indicated that phenol can be initially orto or para hydroxylated to produce cathecol or hydroquinone, respectively, followed by meta-cleavage of aromatic rings. To verify this information, the metabolites obtained from HPLC were submitted to LC/MS to confirm their chemical structure, thereby indicating that the recombinant strains utilize two different routes simultaneously, leading to different ring-fission substrates for the metabolism of phenol. (C) KSBB

Sensory evaluation of black instant coffee beverage with some volatile compounds present in aromatic oil from roasted coffee

The oil obtained from Brazilian roasted coffee by supercritical CO2 extraction shows considerable aromatic properties, mainly composed by five aromatic compounds, 2-methylpyrazine; 2-furfurylalcohol, 2,5-dimethylpyrazine; γ-butyrolactone and 2-furfurylacetate. Sensory analyses were used to verify the influence of a mixture of these important classes of aromatic coffee compounds (pyrazines, furans and lactones) and of the roasted coffee aromatic oil on the coffee aroma and flavour of black instant freeze and spray-dried coffee beverages. In the acceptance evaluation of the aroma, the samples prepared with freeze-dried instant coffee without the mixture of volatile compounds (sample 4) were not significantly different from the freeze-dried instant coffee in which the aromatic coffee oil was added (sample 5) and from the sample prepared with freeze-dried coffee in which the mixture of the five volatile was added (sample 3), coincidentally from the same drying process. Therefore, sample (3) did not differ from samples prepared with spray dried instant coffee without (sample 1) and to which (sample 2) the mixture of volatile was added. Therefore, with respect to this attribute, the addition of this mixture did not interfere in this drink acceptance. Taking into consideration the flavor, samples prepared with freeze-dried instant coffee in which the aromatic coffee oil was added (5) and the samples with (3) and without (4) the mixture of the five volatile was added did not differ significantly, however sample (4) did not differ from samples (1) and (2). Regarding this attribute, the addition of the aromatic oil of roasted coffee or a mixture of volatile in samples of freeze-dried instant coffee had a better acceptance than those dried by spray dryer (1) and (2). Thus, the enrichment of drinks with the aromatic oil of roasted coffee, or even with the mixture of the five components did not influence the consumer acceptance with respect to the aroma, but exerts influence with respect to flavour.