Pyrogenic Hydrocarbons Research Articles

Sources identification and distribution of aliphatic and aromatic hydrocarbons in coastal sediments of Arica Bay – Chile

ABSTRACT This study assesses the first approach regarding the origin, level of contamination, and spatial and vertical distribution of aliphatic and polycyclic aromatic hydrocarbons in coastal sediments of Arica’s Bay. Twenty-seven aliphatic hydrocarbons (AHs) and eighteen polycyclic aromatic hydrocarbons (PAHs) were studied at three depths in sediment cores collected from six locations in the coastal bay. The spatial distribution pattern of the molecular composition of aliphatic and aromatic hydrocarbons is consistent with the directions of the ocean currents from the northeast to the southwest. PAHs are mainly correlated with anthropogenic input sources to the bay. The total aliphatic hydrocarbons showed a wide concentration range from 112.07 to 2,382.43 ng·g−1 dry wt. while total PAHs ranged from 8.01 to 85.40 ng·g−1 dry wt. The vertical distribution of the total AHs shows a tendency to concentrate between 10–20 and 20–30 cm depth. Specific diagnostic characterisation ratios suggest that the bay sediments mainly consist of a mixture of autochthonous, predominantly marine sources composed of marine bacteria (n-C16, n-C18, and C20) and terrestrial plant derivatives (n-C29 and n-C31) and with a contribution of petrogenic hydrocarbons masked by biogenic hydrocarbons. The vertical distribution of the total polycyclic aromatic hydrocarbons is dominated by low molecular weight (LMW) PAHs of two and three rings, such as fluoranthene (FLT), phenanthrene (PHE), pyrene (PYR), and the highest concentrations are found between 10 and 20 cm depth of the sediment column. The PAH diagnostic ratios revealed a mixture of pyrogenic hydrocarbons (biomass and coal combustion) with petrogenic compounds from the Port of Arica and its neighbouring areas. According to the guidelines of UNEP for AHs and PAHs categorisation, the bay’s sediments may be classified from harmless to harmful due to AHs composition and low PAHs pollution.

Dissolved/dispersed polycyclic aromatic hydrocarbon spatial and temporal changes in the Western Gulf of Mexico

Oil extraction and transport activities in the Gulf of Mexico (GoM), along with major marine oil spills and riverine inputs, are exerting environmental pressure on this system by increasing the concentration of oil-related pollutants such as polycyclic aromatic hydrocarbons (PAHs). To fully identify these changes related to oil activities, current PAH levels should be established. Here, we present the PAH concentration and the low molecular weight/high molecular weight (LMW/HMW) ratios obtained in the Perdido Fold Belt area in surface and bottom water at four cruises from May 2016 to September 2017. The Perdido 1 (P1) cruise was conducted in May 2016, the Perdido 2 (P2) cruise in September–October 2016, the Perdido 3 (P3) cruise in June 2017, and the Perdido 4 (P4) cruise in September 2017. Samples were taken during each cruise at up to 3,500-m depth, the deepest ever recorded for the GoM. Results show that the highest concentrations of PAH, LMW PAHs, and HMW PAHs were found in the P4 cruise (1.15, 1.05, and 0.10 µg/L, respectively), well below the 300 µg/L guideline for acute exposure. LMW/HMW ratios show that only the P1 cruise indicates pyrogenic hydrocarbons, while P2, P3, and P4 were petrogenic. The spatial distribution of total PAH, LMW, and HMW showed higher values in the southern and northeastern areas, except for P4, which showed high values related to riverine inputs. The complex hydrodynamic in the region was found to have a significant effect on PAH seasonal changes, river contributions, eddy circulation, and fronts to promote their dispersion.

Paleotoxicity of petrogenic and pyrogenic hydrocarbon mixtures in sediment cores from the Athabasca oil sands region, Alberta (Canada)

Despite the economic benefits of the oil and gas industry in Northern Alberta, significant concerns exist regarding the impacts of increased oil production on the environment and human health. Several studies have highlighted increases in the concentrations of polycyclic aromatic compounds (PACs) and other hydrocarbons in the atmosphere, water, soil and sediments, plants, wildlife and fish in the Athabasca Oil Sands Region (AOSR) as a result of oil sands industrial activity. Sediment cores can provide information on the temporal trends of contaminants to the environment and provide important baseline information when monitoring data are absent. Here we combined analytical chemistry and a mammalian cell-based bioassay in dated lake sediment cores to assess paleotoxicity in freshwater systems in the AOSR. Sediment intervals were radiometrically dated and subsequently analysed for PACs. PAC extracts from select dated intervals were used in cell-based bioassays to evaluate their endocrine disrupting properties. We demonstrated spatial and temporal variability in the PAC composition of sediment cores around the AOSR with some of the highest concentrations of PACs detected near oil sands industrial activity north of Fort McMurray (AB) in La Saline Natural Area. Recent sediment had positive enrichment factors across most PAC analytes at this site with heavier pyrogenic compounds such as benz(a)anthracene/chrysene and benzofluoranthene/benzopyrene dominating. Our study is the first to link chemical analysis of sediment cores with biological effect assessments of endocrine activity showing feasibility of extending the usefulness of sediment cores in monitoring programs interested in complex mixture assessments. While we observed no spatial or temporal differences in ERα mediated signaling, AhR CALUX results mirrored those of the chemical analysis, demonstrating the utility of coupling biological effects assessments to historical reconstructions of contaminant inputs to the natural environment.

Identification of Hydrocarbons in the Waters of Raised Bogs in the Southern Taiga of Western Siberia

The composition and content of hydrocarbons (HCs) in the waters three raised bogs of the south taiga subzone of Western Siberia: the Bolshoe bog, Central bog, and Bakchar bog (which is part of the Great Vasyugan mire) were determined by IR spectrometry, fluorimetry, and chromatography–mass spectrometry. The waters of the bogs are demonstrated to contain hydrocarbons coming from peat deposits (and produced by plants) and pyrogenic hydrocarbons. The Bolshoe bog, which occurs near areas with oil-producing facilities, is the only one whose water contains oil hydrocarbons. The most representative HCs group is n-alkanes whose carbon preference index (CPI) is 4.9–9.2. Among alicyclic HCs, the highest concentrations were detected for triterpenes, with the dominance of taraxerene and neohop-13(18)-ene in the Bolshoe and Bakchar bogs and diploptene in the Central bog. Contamination with oil hydrocarbons, which are transferred by air from oil- and gas-producing facilities, was identified based on the presence of methyl-substituted polycyclic aromatic hydrocarbons (PAHs), steranes, hopanes, and cheilanthanes and by reduced CPI in the water of the Bolshoe bog. The effect of fires in 2016 is inferred from the ratios of unsubstituted PAHs.

Expression of Estrogenic Response Genes in Black Mollies (Poecilia Sphenops) Exposed to Pyrogenic Hydrocarbon and Petroleum from Campeche Sound

The estrogenic effects of endocrine disrupting compounds (EDC´s) in animals are not reversible and can reduce populations. Sensitive methods such Q-PCR have been used to determine changes in gene expression and thus predict the effects before they become irreversible. The present study was designed to detect the expression on the estrogen receptors and vitellogenin genes in the Black Mollies fish (Poecilia sphenops) exposed to pyrogenic hydrocarbon and petroleum from Campeche Sound. The results indicate that the expression of transcript of the estrogen receptor and vitellogenin indicates are potentially useful as molecular biomarker for detecting the presence of endocrine-disruption compounds in environment.

Origin of hydrocarbons in suspended matter and bottom sediments near the Crimean peninsula

It was established that the content of hydrocarbons in the surface waters of the Feodosia Gulf fluctuated were varied a wide range (11–179 μg/l), and exceeded the MPC values for petroleum hydrocarbons in individual samples. The highest concentrations were observed in 2016. The composition of alkanes suggested their mixed (autochthonous and allochthonous) origin. The weathered petroleum hydrocarbons have been identified only in a few cases. In bottom sediments, the concentrations of hydrocarbons depended on their grain size distribution, and terrigenous alkanes were dominated in their composition. The oil and pyrogenic hydrocarbons’ pollution were established based on the composition of polycyclic aromatic hydrocarbons. In the open part of the Black Sea, southward the Crimean peninsula, the hydrocarbon content in surface waters and bottom sediments were at the level of background concentrations, and homologs of terrigenous origin dominated in their composition.

Effects of offshore oil exploration and development in the Alaskan Beaufort Sea: Long-term patterns of hydrocarbons in sediments.

The United States Bureau of Ocean Energy Management (BOEM) has sponsored 4 major monitoring projects in the oil and gas development area of the Alaskan Beaufort Sea since the 1980s, the last being the Arctic Nearshore Impact Monitoring in the Development Area III (ANIMIDA III) Project (2014-2017). These studies were conducted to better understand the physical, chemical, and biological environments and how oil and gas activities may impact them. This paper focuses on monitoring sediment hydrocarbon chemistry. The projects included measuring polycyclic aromatic hydrocarbons (PAHs), n-alkanes and isoprenoids (SHCs), and sterane/triterpene (S/T) geochemical biomarkers and determining their distribution, possible sources, and environmental significance in the sediments of the Beaufort Sea and rivers emptying into it. Concentrations of hydrocarbons in sediments were variable on both spatial and temporal scales; surface sediment concentrations of total PAHs (TPAHs), the class of hydrocarbons of greatest environmental interest, averaged between 300 and 700 μg/kg in different years of monitoring between 1985 and 2015. The concentrations were similar to those measured in other marine regions of Alaska where oil activities have not occurred. Sediment TPAH concentrations were below sediment quality guidelines values, indicating a low risk of harm to benthic marine communities. The hydrocarbons in the Beaufort Sea sediments are primarily from non-oil petrogenic and biogenic sources, with small amounts of pyrogenic hydrocarbons. Most of the hydrocarbons are carried to the Beaufort Sea in coastal erosion and river inputs of hydrocarbon-rich materials, such as peat and shale. The majority of the Beaufort Sea Development Area, including near production facilities, contains uncontaminated sediments with only a few small areas near (<100 m) some exploratory wells where petroleum hydrocarbon concentrations are above regional background. Integr Environ Assess Manag 2019;15:224-236. © 2019 SETAC.

The evolution and formation mechanisms of closed pores in coal

Closed pores, which have been confirmed to exist in coal, have a dual significance in illustrating the tremendous gas outburst content in coal mining and ascertaining the exact methane content in coal, although it is unknown if this methane can be exploited and utilized. In this paper, the principal objective is to explore the evolution and formation mechanisms of closed pores, regarding which there is a lack of knowledge and understanding. We investigated the varieties of closed pore contents in coalification, combining the small angle X-ray scattering (SAXS) and liquid nitrogen adsorption methods (LNA), and simultaneously analyzed the surface topography of closed pores by scanning electron microscopy (SEM). The closed pore volume represents a low-high-low evolution trend during coalification owing to the appearance of gas pores in the pyrogenic hydrocarbon generation stage. However, the specific surface area increases uniformly due to the increase in the number of micro-pores. The tectonic deformation effect impels the increase of closed pores, which reflected in the larger pore volume and specific surface area in strong deformation coal than that in weak deformation coal. The genesis of closed pores can be summarized as a result of heterogeneous matrix shrinkage, the tectonic compressive stress and the tectonic shear stress. Finally, this work provides a novel method to investigate the mechanism of geological CO2 sequestration.

Bioorganic components and compounds of petroleum series in bottom sediments in Lake Tus and Lake Chyornoye (Khakassia)

The distribution of bioorganic components and compounds of anthropogenic and mixed origin in the bottom sediments (BSs) in freshwater Lake Chyornoye and saltwater Lake Tus (Republic of Khakassia) has been studied using the chromatographic mass spectrometric method. The contribution of the major organic matter sources to the BS composition is assessed. It is ascertained that the formation of the BS composition can mostly arise due to the compounds of biogenic and mixed origin. Some lake sites with elevated concentrations of pollutants—petroleum and pyrogenic hydrocarbons and iso-alkylbenzenes as the probable degradation products of surface-active agents—are identified.

Seasonal effect on biomarkers of exposure to petroleum hydrocarbons in fish from Kuwait's marine area

The aquatic biota of the Arabian Gulf deals with exposure to chronic oil pollution, several constituents of which cause induction of Cytochrome P450 1A that serves as a biomarker of AhR ligand exposure. In this study, fluorescent aromatic compounds (FACs) in bile and 7-ethoxyresorufin-o-deethylase (EROD) catalytic activity were determined as a measure of exposure biomarkers in two fish species, yellow fin seabream (Acanthopagrus latus) and tonguesole (Cynoglossus arel) captured from Kuwait Bay and outside the Bay area. FACs in fish bile determined by using fixed-wavelength fluorescence (FF) showed high fluorescence ratios between FF290/335 and FF380/430 indicating predominant exposure to low molecular weight, naphthalene-rich petroleum products (375±91.0pgml−1). Exposures to benzo(a)pyrene-type high-molecular weight polycyclic aromatic hydrocarbons (PAHs) originating from burnt fuel were also present in appreciable concentration in the bile. The ratio of petrogenic to pyrogenic hydrocarbon was twofold higher in winter compared to summer months in both species. Seasonal effect on EROD was significant in tonguesole in Auha site (P<0.05); whereas seabream resisted seasonal change. Tonguesole is considered to be a suitable bioindicator of oil pollution in Kuwait Bay area.

Hydrocarbons in Hydropyrolysis Products of Sapropelic Coals

We have studied the qualitative and quantitative composition of hydrocarbons formed in the hydropyrolysis of sapropelic coals. It was observed that 30-50% of pyrolytic conversions of the organic mass in the studied sapropelic coals at 420°C under hydrogen pressure are associated with the formation of liquid hydrocarbons typical of petroleum kerosene and diesel fractions. It was noted that the hydropyrolysis products contain more alkanes and fewer alkenes and cycloalkanes than the hydrogen-free pyrolysis products. Based on the composition of unbranched, isoprenoid, and cyclic pyrogenic hydrocarbon biomarkers, we draw conclusions concerning the marine origin of the original biomass in the studied coals and the pathways for the formation of hydropyrolysis products from lipid structural components.

Forensic fingerprinting and source identification of the 2009 Sarnia (Ontario) oil spill

This paper presents a case study in which integrated forensic oil fingerprinting and data interpretation techniques were used to characterize the chemical compositions and determine the source of the 2009 Sarnia (Ontario) oil spill incident. The diagnostic fingerprinting techniques include determination of hydrocarbon groups and semi-quantitative product-type screening via gas chromatography (GC), analysis of oil-characteristic biomarkers and the extended suite of parent and alkylated PAH (polycyclic aromatic hydrocarbon) homologous series via gas chromatography-mass spectrometry (GC-MS), determination and comparison of a variety of diagnostic ratios of "source-specific marker" compounds, and determination of the weathering degree of the spilled oil, and whether the spilled oil hydrocarbons have been mixed with any other "background" chemicals (biogenic and/or pyrogenic hydrocarbons). The detailed chemical fingerprinting data and results reveal the following: (1) all four samples are mixtures of diesel and lubricating oil with varying percentages of diesel to lube oil. Both samples 1460 and 1462 are majority diesel-range oil mixed with a smaller portion of lube oil. Sample 1461 contains slightly less diesel-range oil. Sample 1463 is majority lubricating-range oil. (2) The diesel in the four diesel/lube oil mixture samples was most likely the same diesel and from the same source. (3) The spill sample 1460 and the suspected-source sample 1462 have nearly identical concentrations and distribution patterns of target analytes including TPHs, n-alkane, PAHs and biomarker compounds; and have nearly identical diagnostic ratios of target compounds as well. Furthermore, a perfect "positive match" correlation line (with all normalized ratio data points falling into the straight correlation line) is clearly demonstrated. It is concluded that the spill oil water sample 1460 (#1, from the water around the vessel enclosed by a boom) matches with the suspected source sample 1462 (#3, from the vessel engine room bilge pump). (4) From the n-alkane and PAH analysis, it appears that the oil in the spill sample 1460 is slightly more weathered in comparison with sample 1462. The minor differences in fingerprints of two samples were most likely caused by weathering effects. (5) Sample 1461 (#2, from the vessel engine room bilge) and sample 1463 (#4, from the vessel bilge waste collection tank) demonstrated significantly different fingerprints and diagnostic ratios of target compounds from that of spill sample 1460. This was caused most likely by percentages of diesel to lube oil in these two samples different from that in spill sample 1460.

Distribution and sources of hydrocarbons in lagoon sediments of Setiu Wetland, Terengganu, Malaysia

Hydrocarbon compounds viz. aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), sterols, long chain fatty acids, alkanones and alkanals in surface sediment of Setiu Wetland were analysed and characterized using GCMS. The concentration of total identified resolved n-alkanes (TIRNA) in sediment ranged from 2.99–11.6 μ g g− 1 dry weight. The distribution of the aliphatic fraction showed the presence of n-alkanes ranging from C12 to C36 with high predominance for long chain homologues (C25-C31) and a carbon maximum at C29 and C31 with CPI &amp;gt; 3; these observations provide evidence for the presence of biogenic terrigenous input corresponding to epicuticular plant waxes into the lagoon sediments. Positive and strong correlation between n-alkanes associated with terrigenous input (ALK TER) and TIRNA suggest terrestrial input is the main sources of TIRNA in this study area. The absence of unresolved complex mixture (UCM) in the chromatogram and the absence of hopanes, steranes and PAHs compounds are indicative of uncontaminated sediment by petrogenic and pyrogenic hydrocarbons. The concentration of total identified sterols (TIS) ranged from 1.41 μ g g− 1 dry weight to 3.11 μ g g− 1 dry weight with cholesterol, β -Sitosterol and stigmasterol were generally the most dominant and abundant components detected at almost all stations. A positive and strong correlation was observed between B-Sitosterol and TIS and the distribution of long chain n-alkan-2-ones in the range of C21 to C27 with odd to even predominance and n-alkanals (C20 to C28), n-alkanols (C22–C30) and n-alkanoic acids (C22–C30) with even to odd predominance provide further evidence for biogenic sources of hydrocarbons with terrestrial plant input as the predominant source. It was noted that a minor contribution associated with marine phytoplankton (algae) as well as bacteria were also observed in some of the sediment samples superimposing with the terrigenous plant wax input. In general results from this study clearly showed the lagoon sediment of Setiu Wetland is still in uncontaminated condition where terrestrial plants input are the dominant contributor of organic compounds in the sediments with a minor input from marine organisms.

Molecular markers, essential oils and diagnostic parameters as indicators for assessing the origin and constitution of organic matter in atmospheric aerosols

Atmospheric particulate matter was collected at two sites: an Abies boressi forest in central Greece and in Giesta, a coastal-rural site in the centre of Portugal. The extractable organic material consisted primarily of aliphatic hydrocarbons, acids, alcohols, and ketones, with a predominance of molecular weights >C20, derived from vascular plant waxes. Biomarkers for vegetation sources such as phytosterols, triterpenic compounds and essential oils were also detected. Microbial components (>C20), pyrogenic aromatic hydrocarbons and petroleum residues, including hopanes, steranes and cyclic and branched hydrocarbons, were present in the various aerosol extracts. In the apportionment of the various organic fractions to sources, vegetation waxes dominated, contributing to 50?60% of the solvent-extractable material in the aerosols. Petroleum residues and microbial components comprise 25?30% and 15?25% of the organic matter, respectively.

Nonparametric Identification of Petrogenic and Pyrogenic Hydrocarbons in Aquatic Ecosystems

Novel nonparametric models developed herein discriminated between oiled and nonoiled or pyrogenic and oiled sources better than traditionally used diagnostic ratios and can outperform previously published oil identification models. These methods were compared using experimental and environmental hydrocarbon data (sediment, mussels, water, and fish) associated with the Exxon Valdez oil spill. Several nonparametric models were investigated, one designed to detect petroleum in general, one specific to Alaska North Slope crude oil (ANS), and one designed to detect pyrogenic PAH. These ideas are intended as guidance; nonparametric models can easily be adapted to fit the specific needs of a variety of petrogenic and pyrogenic sources. Oil identification was clearly difficult where composition was modified by physical or biological processes; model results differed most in these cases, suggesting that a multiple model approach to source discrimination may be useful where data interpretation is contentious. However, a combined nonparametric model best described a broad range of hydrocarbon sources, thus providing a useful new analytical assessment tool.

Development of oil hydrocarbon fingerprinting and identification techniques

Oil, refined product, and pyrogenic hydrocarbons are the most frequently discovered contaminants in the environment. To effectively determine the fate of spilled oil in the environment and to successfully identify source(s) of spilled oil and petroleum products is, therefore, extremely important in many oil-related environmental studies and liability cases. This article briefly reviews the recent development of chemical analysis methodologies which are most frequently used in oil spill characterization and identification studies and environmental forensic investigations. The fingerprinting and data interpretation techniques discussed include oil spill identification protocol, tiered analytical approach, generic features and chemical composition of oils, effects of weathering on hydrocarbon fingerprinting, recognition of distribution patterns of petroleum hydrocarbons, oil type screening and differentiation, analysis of “source-specific marker” compounds, determination of diagnostic ratios of specific oil constituents, stable isotopic analysis, application of various statistical and numerical analysis tools, and application of other analytical techniques. The issue of how biogenic and pyrogenic hydrocarbons are distinguished from petrogenic hydrocarbons is also addressed.

A Holistic Approach to Hydrocarbon Source Allocation in the Subtidal Sediments of Prince William Sound, Alaska, Embayments

Prince William Sound (PWS), Alaska has an extensive history of human and industrial activity that has produced a complex organic geochemistry record in subtidal sediments of embayments throughout the sound. In addition to contributions from recent oil spills and a regional background of natural petroleum hydrocarbons originating from active hydrocarbon systems in the northern Gulf of Alaska (GOA), pyrogenic and petrogenic PAH were, and continue to be introduced to subtidal sediments at numerous sites of past and present human activities. These sites include villages, fish hatcheries, fish camps and recreational campsites in addition to abandoned settlements, canneries, sawmills, and mines. A holistic approach is used to fingerprint and quantify hydrocarbon contributions from multiple sources in a sediment sample. It involves acquiring a comprehensive understanding of the history of the area to identify potential sources, collection of representative samples, and accurate quantitative analyses of the source and sediment samples for a suite of diagnostic PAH analytes and chemical biomarker compounds. Unlike the deepwater sediments of the sound and GOA, the TOC tool, described elsewhere, does not work as well in some restricted embayments due to their high contents of recent organic matter (ROM). The current study employs a constrained least-squares algorithm to allocate hydrocarbon sources contributing to subtidal sediments collected from PWS embayments in 1991, 1999 and 2000. Results show that sources contributing to the natural petrogenic background are present in the embayments, pyrogenic hydrocarbons including combustion products of diesel are important where human activity was high, and petroleum produced from the Monterey Formation (CA) is present locally. Oil and asphalt shipped from California were widely used for fuel and construction prior to development of the Cook Inlet and North Slope fields. In certain locations that were oiled in 1989, low levels of highly degraded Alaska North Slope crude oil residues attributable to the Exxon Valdez spill remain.

A Holistic Approach to Hydrocarbon Source Allocation in the Subtidal Sediments of Prince William Sound, Alaska, Embayments

Prince William Sound (PWS), Alaska has an extensive history of human and industrial activity that has produced a complex organic geochemistry record in subtidal sediments of embayments throughout the sound. In addition to contributions from recent oil spills and a regional background of natural petroleum hydrocarbons originating from active hydrocarbon systems in the northern Gulf of Alaska (GOA), pyrogenic and petrogenic PAH were, and continue to be introduced to subtidal sediments at numerous sites of past and present human activities. These sites include villages, fish hatcheries, fish camps and recreational campsites in addition to abandoned settlements, canneries, sawmills, and mines. A holistic approach is used to fingerprint and quantify hydrocarbon contributions from multiple sources in a sediment sample. It involves acquiring a comprehensive understanding of the history of the area to identify potential sources, collection of representative samples, and accurate quantitative analyses of the source and sediment samples for a suite of diagnostic PAH analytes and chemical biomarker compounds. Unlike the deepwater sediments of the sound and GOA, the TOC tool, described elsewhere, does not work as well in some restricted embayments due to their high contents of recent organic matter (ROM). The current study employs a constrained least-squares algorithm to allocate hydrocarbon sources contributing to subtidal sediments collected from PWS embayments in 1991, 1999 and 2000. Results show that sources contributing to the natural petrogenic background are present in the embayments, pyrogenic hydrocarbons including combustion products of diesel are important where human activity was high, and petroleum produced from the Monterey Formation (CA) is present locally. Oil and asphalt shipped from California were widely used for fuel and construction prior to development of the Cook Inlet and North Slope fields. In certain locations that were oiled in 1989, low levels of highly degraded Alaska North Slope crude oil residues attributable to the Exxon Valdez spill remain.

The Aegean Sea Oil Spill in the Galicia Coast (NW Spain). I. Distribution and Fate of the Crude Oil and Combustion Products in Subtidal Sediments

The spatial distribution and fate of petrogenic and pyrogenic hydrocarbons in coastal sediments following the Aegean Sea oil spill (Galicia, NW Spain) was investigated through a detailed study of chemical markers. Alkanes and acyclic isoprenoid hydrocarbons were degraded within six months of the accident, but triterpane and sterane distributions were still detectable and were useful in monitoring, respectively, the oil source and weathering. Aromatic steranes were also useful source indicators, and oil degradation was clear from the decrease of certain alkyl dibenzothiophene and phenanthrene isomers. The pyrogenic polycyclic aromatic hydrocarbons produced in the tanker wreck were found more persistent than the petrogenic ones. However, the presence of the oil in the sediments was recognized even one year after the accident and was found particularly preserved in the subsurface layers.

Identification of the Source(s) of Unknown Spilled Oils

ABSTRACT The ability to unambiguously identify spilled oils and petroleum products in complex contaminated environmental samples and to link them to the known sources is extremely important in settling questions of environmental impacts and liability. This paper will briefly review advanced chemical fingerprinting and data interpreting techniques used to identify sources of spilled oils. The chemical fingerprinting techniques discussed include pattern recognition evaluation of target petroleum hydrocarbon distributions; determination of major oil components and hydrocarbon groups; determination of diagnostic ratios of source-specific marker compounds such as PAHs and biomarkers; target PAH isomer analysis; and carbon isotopic ratio analysis. Methods for distinguishing biogenic and pyrogenic hydrocarbons from petrogenic hydrocarbons are also addressed. Several examples are presented to illustrate approaches to identifying and allocating multiple sources of hydrocarbons in complex hydrocarbon mixtures using these advanced chemical fingerprinting techniques.