In Vitro Microbial Degradation of Bituminous Hydrocarbons and In Situ Colonization of Bitumen Surfaces Within the Athabasca Oil Sands Deposit

Bituminous hydrocarbons extracted from the Athabasca oil sands of north-eastern Alberta were adsorbed onto filter supports and placed at sites in the Athabasca River and its tributaries where these rivers come in contact with the oil sands formation. Colonization of the hydrocarbon surfaces at summer and winter ambient temperatures was examined by scanning and transmission electron microscopy as well as by epifluorescence microscopy of acridine orange-stained cross sections. Ruthenium red and alkaline bismuth stains visualized an association of bacteria with the hydrocarbon surface which was mediated by bacterial polysaccharides. Bacteria apparently lacking a glycocalyx were also found closely associated with the surface of the hydrophobic substrate and in channels within the substrate. A solvent precipitation and column chromatographic fractionation of the bitumen was followed by cross-tests for growth on the fractions by various isolated sediment microorganisms, as determined by epifluorescence count. All fractions except the asphaltenes supported the growth of at least two of the isolates, although fractionation of degraded bitumen revealed that the saturate, aromatic, and first polar fractions were preferentially degraded.     

Enhanced procedural blank control for organic geochemical studies of critical sample material

Organic contamination of sedimentary rocks can produce artefacts in studies of hydrocarbon composition, and this can have significant negative consequences for interpretations of the geobiological record. False positives – that is cases of non‐syngenetic hydrocarbon biomarkers – are common in Precambrian studies, and significant challenges persist despite the intensive effort devoted to these studies. Efforts to standardize the ‘burden of proof’ for distinguishing between contamination and syngenetic material have to date failed to yield a simple or universal protocol, yet the need remains great, as both bitumen‐lean rocks and bitumen‐rich samples can be vulnerable to the accumulation of false‐positive signals. In an effort to determine the best approach to quality control, we tested the capability of different blank materials to collect ambient contamination by assessing their capacity to adsorb hydrocarbons during storage in plastic bags and found that commonly used Quartz sand does not provide an adequate measure of storage‐ or laboratory‐induced contamination. Brick blanks, having the advantage that they can parallel rock samples even during the sawing process, are characterized by similar poor adsorption properties. Primarily steered by mineralogy, organic carbon content and surface area, model‐black shales can adsorb up to 20 times more contaminants than sand blanks and up to 200 times more contaminants than organic‐free model‐carbonates. This observation provides an explanation for reports and observations of seemingly systematic stratigraphic variation of contaminants, but mostly should raise awareness for the evaluation of procedural blanks, in particular of sample‐to‐blank ratios, when studying bitumen‐lean rock samples of varying lithologies. Additionally, differences between the hydrocarbon profiles in plastic bags and the hydrocarbon signatures transferred to blank materials emphasize difficulties in the unequivocal detection of contamination sources. Artificial black shale pellets can provide enhanced contamination control in biomarker studies – particularly for exceptionally vulnerable samples such as Precambrian rocks, meteorites or extraterrestrial sample‐return material.     

Microbe-aliphatic hydrocarbon interactions in soil: implications for biodegradation and bioremediation

Aliphatic hydrocarbons make up a substantial portion of organic contamination in the terrestrial environment. However, most studies have focussed on the fate and behaviour of aromatic contaminants in soil. Despite structural differences between aromatic and aliphatic hydrocarbons, both classes of contaminants are subject to physicochemical processes, which can affect the degree of loss, sequestration and interaction with soil microflora. Given the nature of hydrocarbon contamination of soils and the importance of bioremediation strategies, understanding the fate and behaviour of aliphatic hydrocarbons is imperative, particularly microbe-contaminant interactions. Biodegradation by microbes is the key removal process of hydrocarbons in soils, which is controlled by hydrocarbon physicochemistry, environmental conditions, bioavailability and the presence of catabolically active microbes. Therefore, the aims of this review are (i) to consider the physicochemical properties of aliphatic hydrocarbons and highlight mechanisms controlling their fate and behaviour in soil; (ii) to discuss the bioavailability and bioaccessibility of aliphatic hydrocarbons in soil, with particular attention being paid to biodegradation, and (iii) to briefly consider bioremediation techniques that may be applied to remove aliphatic hydrocarbons from soil.     

Evaluation of biogenic and anthropogenic inputs of aliphatic hydrocarbons to Lake Taihu sediments using biomarkers

Surficial sediments from 13 sites throughout Lake Taihu, one of the largest urbanized freshwater lake systems in China, were analyzed for biomarkers (e.g., n-alkanes and hopanes) to track the origin of organic inputs (biogenic or anthropogenic), and, thus, to identify any ‘hot spots’ of hydrocarbon contamination. A distinct spatial distribution of aliphatic hydrocarbons in sediments was observed in Lake Taihu. At the northern tip of the lake (i.e., Meiliang and Wuli Bays), the highest mean aliphatic hydrocarbon concentration, with a significant contribution of an unresolved complex mixture (UCM), was found, indicating possible anthropogenic petroleum contamination (mainly from untreated and partially treated industrial and domestic sewage from Wuxi, Changzhou and other cities). This was supported by the n-alkane indices (e.g., small Carbon Preference Index and odd-to-even values) and a high degree of maturity of the hopane biomarkers. However, hydrocarbons from East Taihu were mainly biogenic, with the lowest mean concentrations, negligible or no contribution of UCM, abundance of vascular plant C₂₃–C₃₃ n-alkanes with a high odd-to-even predominance, and the presence of biogenic hopanes (e.g., 17β(H), 21β(H)-hopanes and hopenes). In the other areas of the lake, however, the predominance of biogenic in combination with petrogenic hydrocarbons was indicated by the biomarkers.     

Nucleolipids as potential organogelators

Four different series of nucleolipids or bola-nucleolipids were synthesized or re-synthesized. Most of the compounds were studied with respect to their gelation properties toward either water or aromatic, hetero-aromatic, and aliphatic hydrocarbons. Bola-nucleolipids 6 and 7 do not gelate any solvent tested, neither as sole additive nor by adding up to 10 wt% of a 1:1 mixture. The nucleolipid 22 carrying the antiviral acyclovir as a head group proved to be a potent organogelator for aromatic hydrocarbons such as toluene, but not for hetarenes, aliphatic hydrocarbons or water. The mono-tailed nucleolipid 24 exhibits excellent organogelator properties for both aromatic and aliphatic hydrocarbons. These were studied as a function of concentration and temperature.     

Physico-Chemical Characterization of Hamster Interferon

The glycoprotein nature of Syrian hamster interferon was tested on several immobilized lectins. The specific retention of small portion (20%) of interferon activity was observed only on concanavalin A-agarose; Component I of the interferon (not retained) has an apparent molecular weight of 23,500 whereas Component II (retained) is larger, 31,500. The apparent hydrophobicity of Syrian hamster interferon was probed by its chromatography on: (a) straight chain hydrocarbons of varied length; (b) aromatic ligands (aminobenzene, benzylamine, β-phenylethylamine, γ-phenyl-propylamine); ligands listed in (a) and (b) were immobilized to cyanogen bromide-activated agarose (isoure linkage); and (c) phenyl-agarose (Phenyl-Sepharose CL-4B), an aromatic ligand immobilized vi 2-hydroxypropyl arm to the agarose (ether linkage).

For a hydrophobic interaction to occur under physiological solvent conditions, the hydrocarbon arm (isourea 1inkage) must be C₉ to C₁₀ carbon atoms long, whereas the aromatic ligand (isourea linkage) must be removed from the agarose matrix by a molecular arm of C₃ carbon atoms. There is no significant binding of hamster interferon to phenyl-agarose (ether linkage) near neutral pH.

The apparent hydrophobicity of Syrian hamster interferon can be profoundly influenced by the pH of the solvent. At lower pH values, interferon binds to both octyl-agarose and phenyl-agarose. The midpoint of transition between binding of interferon and its release from these ligands is about the same, pH 6.0, suggesting the identity of the binding site on the interferon molecule for both aliphatic and aromatic hydrocarbons.     

In situ S‐isotope compositions of sulfate and sulfide from the 3.2 Ga Moodies Group,South Africa: A record of oxidative sulfur cycling

Sulfate minerals are rare in the Archean rock record and largely restricted to the occurrence of barite (BaSO₄). The origin of this barite remains controversially debated. The mass‐independent fractionation of sulfur isotopes in these and other Archean sedimentary rocks suggests that photolysis of volcanic aerosols in an oxygen‐poor atmosphere played an important role in their formation. Here, we report on the multiple sulfur isotopic composition of sedimentary anhydrite in the ca. 3.22 Ga Moodies Group of the Barberton Greenstone Belt, southern Africa. Anhydrite occurs, together with barite and pyrite, in regionally traceable beds that formed in fluvial settings. Variable abundances of barite versus anhydrite reflect changes in sulfate enrichment by evaporitic concentration across orders of magnitude in an arid, nearshore terrestrial environment, periodically replenished by influxes of seawater. The multiple S‐isotope compositions of anhydrite and pyrite are consistent with microbial sulfate reduction. S‐isotope signatures in barite suggest an additional oxidative sulfate source probably derived from continental weathering of sulfide possibly enhanced by microbial sulfur oxidation. Although depositional environments of Moodies sulfate minerals differ strongly from marine barite deposits, their sulfur isotopic composition is similar and most likely reflects a primary isotopic signature. The data indicate that a constant input of small portions of oxidized sulfur from the continents into the ocean may have contributed to the observed long‐term increase in Δ³³S_sulfate values through the Paleoarchean.     

Preservation of overmature,ancient, sedimentary organic matter in carbonate concretions during outcrop weathering

Concretions are preferentially cemented zones within sediments and sedimentary rocks. Cementation can result from relatively early diagenetic processes that include degradation of sedimentary organic compounds or methane as indicated by significantly ¹³C‐depleted or enriched carbon isotope compositions. As minerals fill pore space, reduced permeability may promote preservation of sediment components from degradation during subsequent diagenesis, burial heating and outcrop weathering. Discrete and macroscopic organic remains, macro and microfossils, magnetic grains, and sedimentary structures can be preferentially preserved within concretions. Here, Cretaceous carbonate concretions of the Holz Shale are shown to contain relatively high carbonate‐free total organic carbon (TOC) contents (up to ~18.5 wt%) compared to the surrounding host rock (with <2.1 wt%). TOC increases with total inorganic carbon (TIC) content, a metric of the degree of cementation. Pyrite contents within concretions generally correlate with organic carbon contents. Concretion carbonate carbon isotope compositions (δ¹³C_carb) range from ?22.5 to ?3.4‰ (VPDB) and do not correlate strongly with TOC. Organic carbon isotope compositions (δ¹³C_org) of concretions and host rock are similar. Thermal maturity data indicate that both host and concretion organic matter are overmature and have evolved beyond the oil window maturity stage. Although the organic matter in general has experienced significant oxidative weathering, concretion interiors exhibit lower oxygen indices relative to the host. These results suggest that carbonate concretions can preferentially preserve overmature, ancient, sedimentary organic matter during outcrop weathering, despite evidence for organic matter degradation genetic mechanisms. As a result, concretions may provide an optimal proxy target for characterization of more primary organic carbon concentrations and chemical compositions. In addition, these findings indicate that concretions can promote delayed oxidative weathering of organic carbon in outcrop and therefore impact local chemical cycling.     

Biodegradation of Aliphatic and Aromatic Hydrocarbons by Nocardia sp. H17-1

We investigated the biodegradation of hydrocarbon components by Nocardia sp. H17-1 and the catabolic genes involved in the degradation pathways of both aliphatic and aromatic hydrocarbons. After 6 days of incubation, the aliphatic and aromatic fractions separated from Arabian light oil were degraded 99.0 ± 0.1% and 23.8 ± 0.8%, respectively. Detection of the catabolic genes involved in the hydrocarbon degradation indicated that H17-1 possessed the alkB genes for n-alkane biodegradation and catA gene for catechol 1,2-dioxygenase. However, H17-1 had neither the C23O gene for the degradation of aromatic hydrocarbons nor the catechol 2,3-dioxygenase activity. The investigation of the genes involved in the biodegradation of hydrocarbons supported the low degradation activity of H17-1 on the aromatic fractions.     

The extent and significance of petroleum hydrocarbon contamination in Crater Lake,Oregon

In order to evaluate hydrocarbon inputs to Crater Lake from anthropogenic and natural sources, samples of water, aerosol, surface slick and sediment were collected and analyzed by gas chromatography-mass spectrometry (GC-MS) for determination of their aliphatic and aromatic hydrocarbon concentrations and compositions. Results show that hydrocarbons originate from both natural (terrestrial plant waxes and algae) and anthropogenic (petroleum use) sources and are entering the lake through direct input and atmospheric transport. The concentrations of petroleum hydrocarbons range from low to undetectable. The distributions and abundances of n-alkanes, polycyclic aromatic hydrocarbons (PAH) and unresolved complex mixture (UCM) from petroleum are similar for all surface slick sampling sites. The estimated levels of PAH in surface slicks range from 7–9 ng/m² which are low. Transport of petroleum-derived hydrocarbons from the lake surface has resulted in their presence in some sediments, particularly near the boat operations mooring (total petroleum HC = 1440 μg/kg, dry wt. compared to naturally derived n-alkanes, 240 μg/kg, dry wt.). The presence of biomarkers such as the tricyclic terpanes, hopanes and steranes in shallow sediments further confirms petroleum input from boat traffic. In the deep lake sediments, petroleum hydrocarbon concentrations were very low (16 μg/kg, dry wt.). Very low concentrations of PAH were detected in shallow sediments (17–40 μg/kg at 5 m depth near the boat operations) and deep sediments (3–15 μg/kg at 580 m depth). The individual PAH concentrations in sediments (μg/kg or ppb range) are at least three orders of magnitude less than reported threshold effects levels (mg/kg or ppm range, test amphipod Hyalella azteca). Therefore, no adverse effects are expected to occur in benthic biota exposed to these sediments. Boating activities are leaving a detectable level of petroleum in surface waters and lake sediments but these concentrations are very low.     

Emulsifier of Arthrobacter RAG-1: specificity of hydrocarbon substrate.

The purified extracellular emulsifying factor produced by Arthrobacter RAG-1 (EF-RAG) emulsified light petroleum oil, diesel oil, and a variety of crude oils and gas oils. Although kerosine and gasoline were emulsified poorly by EF-RAG, they were converted into good substrates for emulsification by addition of aromatic compounds, such as 2-methylnaphthalene. Neither aromatic nor aliphatic fractions of crude oil were emulsified by EF-RAG; however, mixtures containing both fractions were emulsified. Pure aliphatic or aromatic hydrocarbons were emulsified poorly by EF-RAG. Binary mixtures containing an aliphatic and an aromatic hydrocarbon, however, were excellent substrates for EF-RAG-induced emulsification. Of a variety of alkylcyclohexane and alkylbenzene derivatives tested, only hexyl- or heptylbenzene and octyl- or decylcyclohexane were effectively emulsified by EF-RAG. These data indicate that for EF-RAG to induce emulsification of hydrocarbons in water, the hydrocarbon substrate must contain both aliphatic and cyclic components. With binary mixtures of methylnaphthalene and hexadecane, maximum emulsion was obtained with 25% hexadecane.     

Emulsifier of Arthrobacter RAG-1: specificity of hydrocarbon substrate.

The purified extracellular emulsifying factor produced by Arthrobacter RAG-1 (EF-RAG) emulsified light petroleum oil, diesel oil, and a variety of crude oils and gas oils. Although kerosine and gasoline were emulsified poorly by EF-RAG, they were converted into good substrates for emulsification by addition of aromatic compounds, such as 2-methylnaphthalene. Neither aromatic nor aliphatic fractions of crude oil were emulsified by EF-RAG; however, mixtures containing both fractions were emulsified. Pure aliphatic or aromatic hydrocarbons were emulsified poorly by EF-RAG. Binary mixtures containing an aliphatic and an aromatic hydrocarbon, however, were excellent substrates for EF-RAG-induced emulsification. Of a variety of alkylcyclohexane and alkylbenzene derivatives tested, only hexyl- or heptylbenzene and octyl- or decylcyclohexane were effectively emulsified by EF-RAG. These data indicate that for EF-RAG to induce emulsification of hydrocarbons in water, the hydrocarbon substrate must contain both aliphatic and cyclic components. With binary mixtures of methylnaphthalene and hexadecane, maximum emulsion was obtained with 25% hexadecane.     

Biodegradation of Aliphatic vs. Aromatic Hydrocarbons in Fertilized Arctic Soils

The objectives of this study were to (1) test a simple bioremediation treatment strategy in the Arctic and (2) examine the effect of fertilization on the degradation of aliphatic and aromatic hydrocarbons. The site is a coarse sand pad that once supported fuel storage tanks. Concentrations of diesel-range organics at the beginning of the study (July 1996) ranged from 250 to 860 mg/kg soil. Replicate field plots treated with fertilizer yielded final concentrations of 0, 50, 100, or 200 mg N/kg soil. Soil samples were collected three times during the thaw season and analyzed for physical and chemical properties, microbial populations and activities, and concentrations of semivolatile hydrocarbons. Soil pH and soil-water potentials declined as a result of fertilizer application. Addition of fertilizer significantly increased soil respiration potentials, but not the populations of microorganisms measured. Fertilizer addition also resulted in ∼50% loss of measured aliphatic and aromatic hydrocarbons in surface and subsurface soils. For fertilized plots, hydrocarbon loss was not related to the amount of fertilizer added. Losses of aliphatic hydrocarbons were attributed to biotic processes, whereas losses of aromatic hydrocarbons likely were a result of both biotic and abiotic processes.     

Volatile Hydrocarbons in Contaminated Soil: Robustness of Fractional Quantification Using Headspace Gas Chromatography-Mass-Spectrometry

Fuel contamination of soils display complex and variable hydrocarbon mixtures with different volatility and toxicity characteristics. A recently suggested headspace procedure for the structure-based quantification of volatile hydrocarbons is evaluated regarding repeatability, reproducibility, and practical robustness. Three aliphatic and three aromatic fractions covering the boiling range between 69 and 216°C were defined as summation parameters by their respective equivalent carbon number ranges. A standard mixture of 35 aliphatic and aromatic hydrocarbons was used for calibration on basis of selected mass fragments specific for the aliphatics and aromatics, respectively. Two standard soils were fortified with the standard mixture or different fuels, respectively, and submitted to the analytical procedure. Limit of detection (LOD) and limit of quantification (LOQ) were for all fractions lower than 0.1 and 0.3 mg/kg, respectively. Analyte recovery was linear up to between 20 and 110 mg hydrocarbons/kg soil depending on the fraction. Hydrocarbon recovery ranged between 80% and 110% depending on the fraction and the repeatability was typically better than 10%. Finally, the impact of extraction solvent variation, column solid-phase polarity, and alternative summation of fractions were investigated. The procedure was applied to liner samples taken from a site contaminated with aviation fuel and its practicability is discussed.     

Importance of Different Volatile Petroleum Hydrocarbon Fractions in Human Health Risk Assessment

Soil vapor data for benzene and four aliphatic and aromatic hydrocarbon fractions from five volatile petroleum hydrocarbon (VPH)-contaminated sites in western Canada were used together with the Canadian Council of Ministers of the Environment (CCME) Canada-Wide Standard for petroleum hydrocarbons to investigate the relative importance of benzene and the different fractions in human health risk assessment. VPH concentrations in soil vapor samples ranged from 4.0 to 4200?mg/m³, of which 0 to 4.6% was BTEX and 90 to 95% was hydrocarbons of the C_5–8 aliphatic fraction. VPH inhalation exposure by an adult receptor in a hypothetical, commercial building was modelled deterministically assuming 16- and 70 year occupational tenures. The magnitude of hazard quotients varied widely between sites, but their hydrocarbon fraction signatures were consistent, and characterized by higher hazard quotients in the C_5–8 and C_9–10 aliphatic and C_9–10 aromatic fractions relative to benzene and the TEX aromatic fraction. This work has shown that the C_5– and C_9–10 aliphatic fractions yield greater relative risk than the commonlyregulated TEX compounds, and that benzene becomes the primary chemical of potential concern only when an occupational tenure approaching 70 years is assumed.     

Nucleolipids as Potential Organogelators

Four different series of nucleolipids or bola-nucleolipids were synthesized or re-synthesized. Most of the compounds were studied with respect to their gelation properties toward either water or aromatic, hetero-aromatic, and aliphatic hydrocarbons. Bola-nucleolipids 6 and 7 do not gelate any solvent tested, neither as sole additive nor by adding up to 10 wt% of a 1:1 mixture. The nucleolipid 22 carrying the antiviral acyclovir as a head group proved to be a potent organogelator for aromatic hydrocarbons such as toluene, but not for hetarenes, aliphatic hydrocarbons or water. The mono-tailed nucleolipid 24 exhibits excellent organogelator properties for both aromatic and aliphatic hydrocarbons. These were studied as a function of concentration and temperature.     

Paleoecology and paleoceanography of the Athel silicilyte,Ediacaran–Cambrian boundary,Sultanate of Oman

The Athel silicilyte is an enigmatic, hundreds of meters thick, finely laminated quartz deposit, in which silica precipitated in deep water (>~100–200 m) at the Ediacaran–Cambrian boundary in the South Oman Salt Basin. In contrast, Meso‐Neoproterozoic sinks for marine silica were dominantly restricted to peritidal settings. The silicilyte is known to contain sterane biomarkers for demosponges, which today are benthic, obligately aerobic organisms. However, the basin has previously been described as permanently sulfidic and time‐equivalent shallow‐water carbonate platform and evaporitic facies lack silica. The Athel silicilyte thus represents a unique and poorly understood depositional system with implications for late Ediacaran marine chemistry and paleoecology. To address these issues, we made petrographic observations, analyzed biomarkers in the solvent‐extractable bitumen, and measured whole‐rock iron speciation and oxygen and silicon isotopes. These data indicate that the silicilyte is a distinct rock type both in its sedimentology and geochemistry and in the original biology present as compared to other facies from the same time period in Oman. The depositional environment of the silicilyte, as compared to the bounding shales, appears to have been more reducing at depth in sediments and possibly bottom waters with a significantly different biological community contributing to the preserved biomarkers. We propose a conceptual model for this system in which deeper, nutrient‐rich waters mixed with surface seawater via episodic mixing, which stimulated primary production. The silica nucleated on this organic matter and then sank to the seafloor, forming the silicilyte in a sediment‐starved system. We propose that the silicilyte may represent a type of environment that existed elsewhere during the Neoproterozoic. These environments may have represented an important locus for silica removal from the oceans.     

Hydrocarbon-degrading filamentous fungi isolated from flare pit soils in northern and western Canada

Sixty-four species of filamentous fungi from five flare pits in northern and western Canada were tested for their ability to degrade crude oil using gas chromatographic analysis of residual hydrocarbons following incubation. Nine isolates were tested further using radiorespirometry to determine the extent of mineralization of model radiolabelled aliphatic and aromatic hydrocarbons dissolved in crude oil. Hydrocarbon biodegradation capability was observed in species representing six orders of the Ascomycota. Gas chromatography indicated that species capable of hydrocarbon degradation attacked compounds within the aliphatic fraction of crude oil, n-C12-n-C26; degradation of compounds within the aromatic fraction was not observed. Radiorespirometry, using n-[1-14C]hexadecane and [9-14C]phenanthrene, confirmed the gas chromatographic results and verified that aliphatic compounds were being mineralized, not simply transformed to intermediate metabolites. This study shows that filamentous fungi may play an integral role in the in situ biodegradation of aliphatic pollutants in flare pit soils.     

Effects of Bacillus subtilis O9 biosurfactant on the bioremediation of crude oil-polluted soils

The application of a surfactant from Bacillus subtilis O9 (Bs) on the bioremediation of soils polluted with crude oil was assayed in soil microcosms under laboratory conditions. Three concentrations of biosurfactant were assayed (1.9, 19.5, and 39 mg kg(-1) soil). Microcosms without biosurfactant were prepared as controls. During the experiment, the crude oil-degrading bacterial population, the aliphatic and aromatic hydrocarbons were monitored in each microcosm. The results indicated that applying Bs did not negatively affect the hydrocarbon-degrading microbial population Concentrations of 19 and 19.5mg (Bs) per kilogram of soil stimulated the growth of the population involved in the crude oil degradation, and accelerated the biodegradation of the aliphatic hydrocarbons. However, none of the assayed Bs concentrations stimulated aromatic hydrocarbon degradation.     

The taphonomic fate of isorenieratene in Lower Jurassic shales—controlled by iron?

Fossil derivatives of isorenieratene, an accessory pigment in brown‐colored green sulfur bacteria, are often used as tracers for photic zone anoxia through Earth's history, but their diagenetic behavior is still incompletely understood. Here, we assess the preservation of isorenieratene derivatives in organic‐rich shales (1.5–8.4 wt.% TOC) from two Lower Jurassic anoxic systems (Bächental oil shale, Tyrol, Austria; Posidonia Shale, Baden‐Württemberg, Germany). Bitumens and kerogens were investigated using catalytic hydropyrolysis (HyPy), closed‐system hydrous pyrolysis (in gold capsules), gas chromatography–mass spectrometry (GC–MS) and gas chromatography combustion isotope ratio‐mass spectrometry (GC‐C‐IRMS). Petrography and biomarkers indicate a syngenetic relationship between bitumens and kerogens. All bitumens contain abundant isorenieratane, diverse complex aromatized isorenieratene derivatives, and a pseudohomologous series of 2,3,6‐trimethyl aryl isoprenoids. In contrast, HyPy and mild closed‐system hydrous pyrolysis of the kerogens yielded only minor amounts of these compounds. Given the overall low maturity of the organic matter (below oil window), it appears that isorenieratene and its abundant derivatives from the bitumen had not been incorporated into the kerogens. Accordingly, sulfur cross‐linking, the key mechanism for sequestration of functionalized lipids into kerogens in anoxic systems, was not effective in the Jurassic environments studied. We explain this by (i) early cyclization/aromatization and (ii) hydrogenation reactions that have prevented effective sulfurization. In addition, (iii) sulfide was locally removed via anoxygenic photosynthesis and efficiently trapped by the reaction with sedimentary iron, as further indicated by elevated iron contents (4.0–8.7 wt.%) and the presence of abundant pyrite aggregates in the rock matrix. Although the combined processes have hampered the kerogen incorporation of isorenieratene and its derivatives, they may have promoted the long‐term preservation of these biomarkers in the bitumen fraction via early defunctionalization. This particular taphonomy of aromatic carotenoids has to be considered in studies of anoxic iron‐rich environments (e.g., the Proterozoic ocean).