Petroleum Polycyclic Aromatic Hydrocarbons Research Articles

Ultra-low hydrogen content bowl-shaped polycyclic aromatic hydrocarbons in petroleum

In the ultra-high resolution mass spectrometric analysis of processed petroleums (fossil materials), we observed species with ultra-low hydrogen content (e.g. H/C ratio from 0.1 to 0.4). Some of the observed chemical formula (C20-40H10) can be rationalized by the known corannulene-based peri-condensed Polycyclic Aromatic Hydrocarbons (PAHs). Other formulas (such as C20-40H8, C20-40H6 and C20-40H4) cannot be rationalized with any known structures. We proposed highly curved non-planar PAHs involving multiple connected five member aromatic rings. These structures do not obey the isolated pentagon rule (IPR). The stabilities of the proposed structures were evaluated by density functional theory. Strain energies were calculated based on hypothetical isodesmic conversion of planar structures to the curved non-planar structures. Results showed that the strain energies of the proposed structures are lower than that of fullerenes of the same carbon number, confirming stabilities of the non-IPR structures. The low hydrogen content species are likely formed in the thermal and/or catalytic cracking of the petroleums. They are possible intermediate molecules on the path toward the formation of fullerenes (buckyballs) and other nano-carbon materials

Investigating the degradation of nC12 to nC23 alkanes and PAHs in petroleum- contaminated water by electrochemical advanced oxidation process using an inexpensive Ti/Sb-SnO2/PbO2 anode

Electrochemical advanced oxidation experiments were conducted to investigate the degradation of total petroleum hydrocarbons (TPH), nC12 to nC23 alkanes and priority pollutants such as polycyclic aromatic hydrocarbons (PAHs) in petroleum-contaminated water using an inexpensive Ti/Sb-SnO2/PbO2 anode. The influence of electrolyte, applied current, treatment time, and electrode surface area was assessed. Under optimal conditions of energy and 2.5 h of treatment, the TPH removal percentages were 85.44% and 85.61% in Na2SO4 and NaCl electrolytes, respectively. The effect of external electrolyte on TPH degradation was marginal at smaller electrodes (12 cm2) and found to be negligible at larger electrodes (30 cm2). Results demonstrated that TPH degradation was not significantly influenced by active chlorine species (Cl2, HOCl) generated in the NaCl electrolyte other than hydroxyl radicals. The lighter n-alkanes (nC12 to nC14) had exhibited greater removal percentages (90.65% to 98.8%) than medium alkanes (nC15 to nC18: 81% to 89%) and heavier alkanes (nC19 to nC23: 81% to 84.3%). n-Alkanes were resistant to oxidation at low concentrations, possibly due to the inter-phase mass transfer resistance between polar free-radicals and non-polar alkanes. PAHs were completely disappeared (~99.99%) owing to their high reactivity towards free radicals. GC–MS analysis revealed that the n-alkanes had transformed to alcohols, aldehydes, carboxylic acids, and esters before mineralization. The degradation pathway for PAHs involves the formation of hydroxylated products, chlorinated products, aromatic ring-opening products, acids, and esters. The toxicity, as evaluated by Vibrio-fischeri inhibition tests, was decreasing in Na2SO4 medium and increasing in NaCl medium following the electrochemical oxidation treatment. This increase in toxicity in NaCl medium was found to be due to electro-generated active chlorine species.

Determination and Remediation of Selected Polycyclic Aromatic Hydrocarbons in Petroleum Contaminated Water

Determination and remediation of pollutants such as polycyclic aromatic hydrocarbons (PAHs) have not being fully regulated in Nigeria; hence contamination of surface water by such pollutant is a major concern. This study was designed to determine the level of selected PAHs in petroleum contaminated water using spectroscopic techniques and the efficacy of activated carbons made from Bambusa vulgaris and Oxytenanthera vabyssinaca. Bambusa vulgaris and Oxytenanthera abyssinaca were carbonized at 350OC and activated with Phosphoric acid (CBV350OC H3PO4) and Potassium chloride (COA 350OC KCl) as dehydrating agent respectively. The adsorbents were then used to remediate PAHs in petroleum contaminated water. Liquid-Liquid extraction procedures were used for extracting selected PAHs from sampled solutions. The batch experiment was performed to study the adsorption capacity of adsorbents at 5hrs contact time. Analysis of PAHs concentration for each sampling day was determined by GC-MS. Total PAHs in simulated wastewater did not show a clear trend, contrary to the expectation that there should be a progressive increase with time due to photolysis or photodecomposition of compounds or PAHs. COA 350OC KCl showed a range of 6.2-19.3% removal efficiency of each selected PAH with a total percentage efficiency of 27.7-70.8 for all days. For CBV350OC H3PO4 removal efficiency ranged from 10.26-19.30% for each selected PAH and a total efficiency of 50.8-100% for all selected PAHs for the 4 days intervals. The experimental result showed that adsorbent made from Bambusa vulgaris and Oxytenanthera abyssinaca and activated with H3PO4 and KCl as dehydrating agentrespectively can efficiently adsorb the selected PAHs in contaminated water. The study also revealed that PAHs in contaminated water increases with time due to photodecomposition, thus necessitating their treatment on time.

Quantification of Naphthalene Dioxygenase (NahAC) and Catechol Dioxygenase (C23O) Catabolic Genes Produced by Phenanthrene-Degrading Pseudomonas fluorescens AH-40.

Background Petroleum polycyclic aromatic hydrocarbons (PAHs) are known to be toxic and carcinogenic for humans and their contamination of soils and water is of great environmental concern. Identification of the key microorganisms that play a role in pollutant degradation processes is relevant to the development of optimal in situ bioremediation strategies.Objective Detection of the ability of Pseudomonas fluorescens AH-40 to consume phenanthrene as a sole carbon source and determining the variation in the concentration of both nahAC and C23O catabolic genes during 15 days of the incubation period.Methods In the current study, a bacterial strain AH-40 was isolated from crude oil polluted soil by enrichment technique in mineral basal salts (MBS) medium supplemented with phenanthrene (PAH) as a sole carbon and energy source. The isolated strain was genetically identified based on 16S rDNA sequence analysis. The degradation of PAHs by this strain was confirmed by HPLC analysis. The detection and quantification of naphthalene dioxygenase (nahAc) and catechol 2,3-dioxygenase (C23O) genes, which play a critical role during the mineralization of PAHs in the liquid bacterial culture were achieved by quantitative PCR.Results Strain AH-40 was identified as pseudomonas fluorescens. It degraded 97% of 150 mg phenanthrene L-1 within 15 days, which is faster than previously reported pure cultures. The copy numbers of chromosomal encoding catabolic genes nahAc and C23O increased during the process of phenanthrene degradation.ConclusionnahAc and C23O genes are the main marker genes for phenanthrene degradation by strain AH-40. P. fluorescence AH-40 could be recommended for bioremediation of phenanthrene contaminated site.

16S rDNA Phylogenetic and RAPD–PCR Analyses of Petroleum Polycyclic Aromatic Hydrocarbons-Degrading Bacteria Enriched from Oil-Polluted Soils

Petroleum polycyclic aromatic hydrocarbons (PAHs) are health risks to human, as they can be toxic, mutagenic and carcinogenic. As the Kingdom of Saudi Arabia is one of the major petroleum-producing countries, they inevitably suffer from worsening this environmental problem. Therefore, removal of these compounds from the environment is a necessity for ensuring human health. In this study, 54 bacterial isolates were obtained by enrichment techniques from oil-contaminated soil samples. Out of them, seven gram-negative bacterial strains, KKU-J1, KKU-J2, KKU-J4, KKU-J7, KKU-J9, KKU-J14 and KKU-J17, exhibiting ability for petroleum PAHs degradation were selected. The isolates showing the highest growth during screening as demonstrated by the increase in their optical densities (OD600) and a concentration-dependent growth in all examined PAH compounds that grew in it, with strains KKU-J2, KKU-J7 and KKU-J17 were the best. The highest optimum growth rate of \({0.333 \pm 0.0, 0.364 \pm 0.016}\) and \({0.357 \pm 0.004 ({\rm OD}_{600})}\) was recorded for the strains KKU-J2, KKU-J7 and KKU-J17, respectively, when the level of phenanthrene was 100 mg/l. On the other hand, strain KKU-J2 was found to be the best one (\({0.413 \pm 0.0}\)) when the level of naphthalene was 100 mg/l. Molecular identification of the selected isolates was detected based on 16S rRNA gene amplification and partial sequence determination. Alignment results and the comparison of 16S rRNA gene sequences of the isolates to the 16S rRNA gene sequences available in GenBank database, as well as the phylogenetic analysis, confirmed the accurate position of the isolates as Sphingomonas paucimobilis KKU-J1, Pseudomonas alcaligenes KKU-J2, Micrococcus antarcticus KKU-J4, Arthrobacter oxydans KKU-J7, Stenotrophomonas rhizophila KKU-J9, Kocuria rhizophila KKU-J14 and Shinella zoogloeoides KKU-J17. RAPD–PCR fingerprinting was carried out for the seven isolates, and the DNA patterns revealed that there is no correlation between the RAPD profile and geographic origin sites where these isolates were collected from. This study indicates that the contaminated soil samples contain a diverse population of PAH-degrading bacteria, and the use of soil-associated microorganisms could be recommended for PAHs bioremediation in the environment.

Development of a methodology for accurate quantitation of alkylated polycyclic aromatic hydrocarbons in petroleum and oil contaminated environmental samples

Polycyclic aromatic hydrocarbons (PAHs) are compounds of concern because most of these compounds are toxic, carcinogenic, or mutagenic and are relatively persistent in the environment. Reliable quantitative information of PAHs is important to evaluate the acute and chronic harmful effects of PAHs on the ecosystem. Crude oils and refined petroleum products contain many highly abundant PAHs and heterocyclic PAHs, in particular the alkylated homologues of naphthalene, phenanthrene, dibenzothiophene, fluorene and chrysene (APAH). The alkylated PAH homologues usually occur in significantly higher concentrations than their corresponding unsubstituted parent PAHs. Petrogenic alkylated PAHs generally consist of large numbers of isomers. Unlike those individual unsusbstituted PAHs, most of the APAH isomers are not commercially available. Therefore, historically, the target APAHs are generally quantified using the relative response factors (RRFs) obtained from their respective unsubstituted parent PAH compounds, this inevitably results in the quantitative results of APAH being significantly underestimated. In order to improve the accuracy of the measurement of PAHs and their alkylated homologues in oil and oil related samples, this study measured and compared the response factors of a large number of alkylated PAHs relative to the internal standards in gas chromatography-mass spectrometry (GC-MS) analysis, with the goal of developing a more accurate quantitative methodology for the determination of oil APAHs, and eventually leading to a standardized methodology of quantitative APAH analysis. The PAHs in different oils and related environmental samples collected from oil impacted areas were determined using this GC-MS methodology. Furthermore, the influence of the measurement methodology on the diagnostic ratios of target PAHs was also assessed in this work.

Biota – Sediment partitioning of aluminium smelter related PAHs and pulp mill related diterpenes by intertidal clams at Kitimat, British Columbia

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

Distribution and source apportionment of polycyclic aromatic hydrocarbons (PAH) in water and sediments of the Luan River, China

The distribution of polycyclic aromatic hydrocarbons (PAH) was studied by determining the levels of 16 PAH in the water and sediment samples of the Luan River; a very important drinking water source for Tianjin and Tangshan in Hebei province, China. A total of 11 water samples and 11 sediment samples were collected in April 2008. The total PAH concentrations in water varied from 9.8 to 310 ng L−1, and those in surficial sediments ranged from not detected (ND) to 478 ng g−1 dry weight. The results showed that the upstream and downstream areas were low-polluted and high-polluted sites concentrated in the middle reaches of the river, respectively. The concentrations of PAH in rural areas (5 sites), which could be considered as the “background” levels, were lower than those near city zones (6 sites), which could be regarded as the “maximum” values. The PAH were dominated by 3- (38.4%) and 4-ring (60.7%) components in water samples and by 3- (27.4%), 4- (38.5%), and 5-ring (15.8%) compounds in sediments. High molecular weight PAH were inclined to be absorbed into sediments. The 3- and 4-ring PAH were the most common components in the Luan River. The molecular indices and the distribution of different rings were used to infer the sources of PAH, and the results suggested that anthropogenic heavy fuel combustion was likely to be the main source. The petroleum PAH had a high contribution to the PAH pollution at Baohekou and Daheiting.

Concentration Dependence in the Spectra of Polycyclic Aromatic Hydrocarbon Mixtures by Front-Surface Fluorescence Analysis

Polycyclic aromatic hydrocarbons (PAHs) are a challenge for fluorescence analysis. Inner-filter quenching effects and energy transfers of PAHs in petroleum differ with concentration, leading to characteristically different fluorescence. At high concentrations of single PAH molecules and petroleum mixtures the classic rectangular quartz cell presents a particular challenge due to inner filter effects from right-angle illumination. While quite a few instrumental and mathematical corrections for these effects are reported throughout the literature, for researchers with standard instrumental sample compartments a triangular fluorometer cell can be used to emulate front-surface fluorescence analysis. This work presents concentration study results from the single PAH molecules fluoranthene and azulene dissolved in spectral-grade cyclohexane and also seeks to correct an aspect of our past work on the fluorescence of petroleum mixtures.

PAHS AND OTHER CONTAMINANTS IN EFFLUENTS FROM ARTIFICIALLY WEATHERED OIL ON GRAVEL

ABSTRACT Several recent studies report that low parts per billion (ppb) concentrations of petroleum polycyclic aromatic hydrocarbons (PAH) are toxic to marine fish embryos and that crude oil toxicity increases as it weathers. Such claims for Pacific herring embyros derive from two experiments by Carls et al. (1999) in which herring eggs were exposed to seawater passed through gravel coated with artificially weathered Alaska North Slope crude oil. The experiments differed in the extent of weathering of the oil on gravel. Carls et al. reported that developmental abnormalities in herring embryos occur during chronic exposure to PAH levels as low as 0.4 ppb in seawater passed through the oiled gravel. Earlier studies had shown that effects are observed at low PAH levels only when oil droplets or films adhered to the herring eggs. To better understand Carls et al. experiments, we examined effluent from a gravel bed prepared following Carls et al. and report that ammonia, sulfides, and oil droplets were present in the effluent from oiled gravel generators that were shut down between two 16-day trials (as was done by Carls et al.). Oil droplets (0.5 to 1 mm) were intermittently present in effluent from oiled gravel generators even when the flow was continuous. Two hours after restarting flow, low dissolved oxygen, ammonia, and sulfides were present in the generators and in the effluent. Droplets, ammonia, and sulfides all induce developmental abnormalities of the types seen by Carls et al. The presence of ammonia and sulfide in the effluent after shutdown is a laboratory artifact and constitutes clear evidence of anaerobic biodegradation of the oil on gravel. Evidence of anaerobic biodegradation suggests that the exposure regime of Carls et al. did not effectively simulate field conditions. Our results demonstrate that the presence of confounding toxicants in the Carls et al. experiments cannot be dismissed. There is no basis to conclude that aqueous exposure to low ppb PAH levels affects herring eggs or that weathering increases oil toxicity to fish eggs without additional experiments that specifically account for the potential confounding factors and all chemicals in effluents from oiled gravel columns.

Molecular characterization and substrate preference of a polycyclic aromatic hydrocarbon dioxygenase from Cycloclasticus sp. strain A5.

Cycloclasticus sp. strain A5 is able to grow with petroleum polycyclic aromatic hydrocarbons (PAHs), including unsubstituted and substituted naphthalenes, dibenzothiophenes, phenanthrenes, and fluorenes. A set of genes responsible for the degradation of petroleum PAHs was isolated by using the ability of the organism to oxidize indole to indigo. This 10.5-kb DNA fragment was sequenced and found to contain 10 open reading frames (ORFs). Seven ORFs showed homology to previously characterized genes for PAH degradation and were designated phn genes, although the sequence and order of these phn genes were significantly different from the sequence and order of the known PAH-degrading genes. The phnA1, phnA2, phnA3, and phnA4 genes, which encode the alpha and beta subunits of an iron-sulfur protein, a ferredoxin, and a ferredoxin reductase, respectively, were identified as the genes coding for PAH dioxygenase. The phnA4A3 gene cluster was located 3.7 kb downstream of the phnA2 gene. PhnA1 and PhnA2 exhibited moderate (less than 62%) sequence identity to the alpha and beta subunits of other aromatic ring-hydroxylating dioxygenases, but motifs such as the Fe(II)-binding site and the [2Fe-2S] cluster ligands were conserved. Escherichia coli cells possessing the phnA1A2A3A4 genes were able to convert phenanthrene, naphthalene, and methylnaphthalene in addition to the tricyclic heterocycles dibenzofuran and dibenzothiophene to their hydroxylated forms. Significantly, the E. coli cells also transformed biphenyl and diphenylmethane, which are ordinarily the substrates of biphenyl dioxygenases.

Alkane and PAH depositional history, sources and fluxes in sediments from the Fraser River Basin and Strait of Georgia, Canada

Hydrocarbon data for dated sediment cores from Fraser Basin lakes and the Strait of Georgia in Canada reveal a pristine pre-industrial background that remains unaltered in modern sediments far from human activities. These pristine sediments contain polycyclic aromatic hydrocarbons (PAHs) from combustion (natural forest and prairie fires), and alkanes and PAHs from weathering of soils containing vascular plant remains and natural petroleum hydrocarbons, and algal production. At other locations examined, however, these natural loadings have been augmented over the past century by hydrocarbons from petroleum, the combustion of liquid (oil, gasoline) and solid (coal, wood) fuels and from processing of wood either directly from disturbed land and slash burning or indirectly through pulp mill effluent. Although contamination is clearest where there are nearby human activities, alkane profiles, PAH distributions and alkane unresolved complex mixtures suggest a widespread contamination from petroleum. Combustion products from human activities can also be identified, although with less source specificity than with the petroleum products. Regional emissions from anthropogenic combustion processes appear to support modern PAH increases within the Fraser River Basin and there is little evidence of inputs from global emissions. Principal components analysis using the new centred log ratio normalisation procedure to normalise data discriminates well between PAHs entering lakes from runoff or the atmosphere and PAH formed diagenetically within lake sediments, as well as between combustion and petroleum PAHs.

Oxidation of polycyclic aromatic hydrocarbons by fungal isolates from an oil contaminated refinery soil.

Indigenous soil microorganisms are used for the biodegradation of petroleum hydrocarbons in oily waste residues from the petroleum refining industry. The objective of this investigation was to determine the potential of indigenous strains of fungi in soil contaminated with petroleum hydrocarbons to biodegrade polycyclic aromatic hydrocarbons (PAH). Twenty one fungal strains were isolated from a soil used for land-farming of oily waste residues from the petrochemical refining industry in Singapore and identified to genus level using laboratory culture and morphological techniques. Isolates were incubated in the presence of 30 mg/L of phenanthrene over a period of 28 days at 30 degrees C. The most effective strain was further evaluated to determine its ability to oxidise a wider range of PAH compounds of various molecular weight i.e acenaphthene, fluorene, fluoranthene, chrysene, benzo(a)pyrene and dibenz(ah)anthracene After 28 days of incubation, 18 of the 21 fungal cultures were capable of oxidising over 50% of the phenanthrene present in culture medium, relative to abiotic controls. Fungal isolate, Penicillium sp. 06, was able to oxidise 89% of the phenanthrene present. This isolate could also oxidise more than 75% of the acenaphthene, fluorene and fluoranthene after 30 days of incubation. However, the oxidation of high molecular weight PAH i.e. chrysene, benzo(a)pyrene and dibenz(ah)anthracene by the Penicillium sp. 06 isolate was limited, where the extent of oxidation was inversely proportional to PAH molecular weight. Fungal isolate, Penicillium sp. 06, was effective at oxidising a range of PAH in petroleum contaminated soils, but higher molecular weight PAH were more recalcitrant. There is potential for the re-application of this fungal strain to soil for bioremediation purposes.

Dissolved and Suspended Polycyclic Aromatic Hydrocarbons (PAH) in the North Aegean Sea

The distribution and sources of polycyclic aromatic hydrocarbons (PAH) were investigated in the seawater of the North Aegean Sea. The measured PAH concentrations in SPM are generally considered as elevated for open sea waters and were evenly distributed in the area. Their levels in the dissolved phase (1.6-33.0 ng/l) were much higher than those encountered in the corresponding particulate phases (0.04-10.2 ng/l). The PAH patterns in both phases were dominated by the three ring aromatics and their alkylated derivatives, reflecting a predominant contribution of fossil hydrocarbons probably related to ship traffic, whereas no significant inputs from the rivers outfalling in the area were detected. In bottom waters PAH values were generally lower, whereas a higher depletion of the petroleum PAH in comparison with the pyrolytic ones according to depth was observed.

New approach to study of spilled crude oils using high resolution GC-MS (SIM) and metastable reaction monitoring GC-MS-MS

Polycyclic aromatic hydrocarbons (PAHs) and geochemical biomarkers are good environmental markers to study the origin and evolution of an oil spill. To have access to the greatest number of molecular ratios, no fractionation of oil into aliphatic and aromatic compounds is made. Three analytical MS approaches are tested to analyze markers in this total hydrocarbon fraction: classical quadrupole GC-MS, high resolution GC-MS (HR GC-MS) and metastable reaction monitoring GC-MS-MS (MRM GC-MS-MS). This analytical approach is used to follow the evolution of PAHs in petroleum polluted mangrove soils over 8 years by using molecular ratios between polycyclic aromatic hydrocarbons and tri- and tetracyclic terpanes.

Selective Aerobic Degradation of Methyl-Substituted Polycyclic Aromatic Hydrocarbons in Petroleum by Pure Microbial Culturest

Abstract Studies of laboratory degradation of Arabian light crude oil (b.p. < 200°C) by pure cultures of bacterial strains Pseudomonas sp. isolated from tanker ballast waters showed that biodegradation of alkyl-substituted polycyclic aromatic hydrocarbons strongly depends on the number, position, and the type of the substituents. Biodegradation of alkylphenanthrenes and dibenzothiophenes decreased with increasing number of substitutents. Biodegradation of methylphenanthrenes (P), dibenzothiophenes (DBT), pyrenes (Py) and chrysenes (C) showed a pattern similar to that previously observed for the methylnapthalenes; compounds containing unsubstituted α and β adjacent positions were more readily degraded. Thus, 2- and 3-MP, 2- and 3-MDBT, 1-MPy and 2- and 3-MC were shown to be less resistant to degradation within these families. Cycloalkylaromatics, such as partially aromatized steranes, hopanes and 8, 14-secohopanes were generally resistant to degradation by the cultures employed.

Embryotoxic effects of benzo[a]pyrene, chrysene, and 7,12-dimethylbenz[a]anthracene in petroleum hydrocarbon mixtures in mallard ducks.

Studies with different avian species have revealed that surface applications of microliter amounts of some crude and fuel oils that coat less than 10% of the egg surface result in considerable reduction in hatching with teratogenicity and stunted growth. Other studies have shown that the embryotoxicity is dependent on the aromatic hydrocarbon content, further suggesting that the toxicity is due to causes other than asphyxia. In the present study the effects of three polycyclic aromatic hydrocarbons identified in petroleum were examined on mallard (Anas platyrhynchos) embryo development. Addition of benzo[a]pyrene (BaP), chrysene, or 7,12-dimethylbenz[a]anthracene (DMBA) to a synthetic petroleum hydrocarbon mixture of known composition and relatively low embryotoxicity resulted in embryotoxicity that was enhanced or equal to that of crude oil when 10 microliter was applied externally to eggs at 72 h of development. The order of ability to enhance embryotoxicity was DMBA greater than BaP greater than chrysene. The temporal pattern of embryonic death was similar to that reported after exposure to crude oil, with additional mortality occurring after outgrowth of the chorioallantois. Retarded growth, as reflected by embryonic body weight, crown-rump length, and bill length, was accompanied by teratogenicity. Abnormal embryos exhibited extreme stunting; eye, brain, and bill defects; and incomplete ossification. Gas chromatographic-mass spectral analysis of externally treated eggs showed the passage of aromatic hydrocarbons including chrysene through the shell and shell membranes to the developing embryos. These findings suggest that the presence of polycyclic aromatic hydrocarbons in petroleum, including BaP, chrysene, and DMBA, significantly enhances the overall embryotoxicity in avian species.

Origins of polycyclic aromatic hydrocarbons in estuarine sediments

In order to determine the origin of polycyclic aromatic hydrocarbons (PAHs) in sediments from Narragansett Bay, Rhode Island, the PAH assemblages from the sediments and from possible origin materials were analyzed by gas Chromatographic and gas chromatographic-mass spectrometric techniques. Analyses included determinations of: 1. (1) the relative content of non-alkylated PAH parent molecules i.e. parent compound distributions (PCDs); 2. (2) alkylation patterns of these PAH molecules, i.e. alkyl homolog distributions (AHDs); and 3. (3) phenanthrene/anthracene (P/A) ratios. Samples from the Narragansett Bay transect, which began at a sewage outfall for the City of East Providence, Rhode Island, and ended 20 km to the south, showed rapidly decreasing concentrations of PAH compounds with increasing distance from Providence. The PAH assemblages in transect sediment samples, and in other samples collected near piers, showed evidence for different origins. The sediments surrounding tarred piers were contaminated by coal tar used to coat the pilings. The close resemblance of PCDs from bay sediments and combustion products indicated that the PAHs in the transect sediments were predominantly combustion generated. While evidence for the input of PAHs from petroleum to bay sediments appeared in some AHDs of upper bay transect sediments, AHDs from the lower (less polluted) end of the transect showed less influence of petroleum PAH contamination. In general, the shapes of AHDs from transect sediments of Narragansett Bay appeared to be best explained by a combination of inputs of PAHs from petroleum and combustion processes, rather than by the solubility alteration of PAH assemblages on incoming airborne material.

Analysis of polycyclic aromatic hydrocarbons in petroleum waxes and white mineral oils with appraisal of merits of different methods of analysis

We present a critical discussion, based on our own experimental work, of the merits of two different methods for determining and estimating polycyclic aromatic hydrocarbon (PAH) compounds in refined paraffin waxes and white mineral oils. The Food and Drug Administration (FDA) in the USA has developed a method involving extraction of PAH compounds from wax for quantitative estimation by ultraviolet spectrophotometry of the total PAH content. In W. Germany two methods have been developed: one based on fluorescence of molten wax, the other on paper chromatography applied to a nitromethane extract of PAH compounds. The method employing fluorescence of the molten wax, however, is of little value, because the activating rays, wavelength 254 mμ are absorbed by mono- and bicyclic aromatic components naturally present in the wax. This leads to quenching of the fluorescence, even for waxes passing the requirements of the W. German sulphuric acid test intended to detect fluorescence quenchers. In the other method, the paper-chromatographic behaviour of the PAH extract of the wax is compared with that of three known carcinogenic PAH compounds. We have found that the retention values of these reference carcinogens, added intentionally to the wax extract, are not reproducible and that the fluorescent band is displaced irregularly by other components extracted from the wax, so that a comparison with the reference chromatogram is hardly possible. In addition, quenching takes place, the extent of which is dependent upon the type of PAH and on the type of wax. From our investigations, which cover more PAH compounds than those mentioned explicitly by the W. German law, we conclude that the reliability of both W. German methods is insufficient. We prefer the FDA method, because it is very reproducible and always gives the total PAH content. Moreover, this method has been developed in conjunction with toxicological experiments on animals.