Individual Aromatic Hydrocarbons Research Articles

Development of an effective QSAR-based hazard threshold prediction model for the ecological risk assessment of aromatic hydrocarbon compounds.

The insufficient hazard thresholds of specific individual aromatic hydrocarbon compounds (AHCs) with diverse structures limit their ecological risk assessment. Thus, herein, quantitative structure-activity relationship (QSAR) models for estimating the hazard threshold of AHCs were developed based on the hazardous concentration for 5% of species (HC5) determined using the optimal species sensitivity distribution models and on the molecular descriptors calculated via the PADEL software and ORCA software. Results revealed that the optimal QSAR model, which involved eight descriptors, namely, Zagreb, GATS2m, VR3_Dzs, AATSC2s, GATS2c, ATSC2i, ω, and Vm, displayed excellent performance, as reflected by an optimal goodness of fit (R2adj = 0.918), robustness (Q2LOO = 0.869), and external prediction ability (Q2F1 = 0.760, Q2F2 = 0.782, and Q2F3 = 0.774). The hazard thresholds estimated using the optimal QSAR model were approximately close to the published water quality criteria developed by different countries and regions. The quantitative structure-toxicity relationship demonstrated that the molecular descriptors associated with electrophilicity and topological and electrotopological properties were important factors that affected the risks of AHCs. A new and reliable approach to estimate the hazard threshold of ecological risk assessment for various aromatic hydrocarbon pollutants was provided in this study, which can be widely popularised to similar contaminants with diverse structures.

EFFECT OF AN ALKYL SUBSTITUTE ON HYDROCONVERSION OF INDIVIDUAL AROMATIC HYDROCARBONS ON Co/HZSM-5/SO42-–ZrO2 COMPOSITE CATALYST

A systematic study of the hydrogenation of individual aromatic hydrocarbons (benzene, toluene, xylene) and their mixtures was carried out at 1800C, H2/Ar=7, WHSV = 2h-1 and atmospheric pressure on a composite catalyst 0.4%Co/HZSM-5/SO42-(2.0%)–ZrO2. It has been established that the developed catalyst has a high hydrogenating ability with respect to aromatic hydrocarbons at low hydrogen pressures. Alkyl-substituted benzenes turned out to be more active. It was found that alkyl substituents increase the activity of hydrogenation of the benzene ring of an aromatic hydrocarbon. According to their conversion, benzene, toluene and xylene form the following sequence: benzene<toluene<xylene. It was found that the optimal temperature for the process of hydroconversion of aromatic hydrocarbons on a composite catalyst is 1800C. The influence of the concentration of the hydrogenating component of the catalyst – Co on the hydroconversion was also investigated. It was found that the optimal concentration of Co is 0.4wt %. It has been established that in a benzene:toluene:xylene mixture, the conversion of benzene in comparison with its separate hydroconversion increases by more than 10%. The hydroconversion of aromatic hydrocarbons is accompanied by the formation of high-octane naphthenic hydrocarbons - cyclohexane, methylcyclohexane and methylcyclopentane. The antibatic change in the yield of CH and MCP with the duration of the experiment shows that the hydrogenation of the aromatic ring is primary and the isomerization of C6H10 to MCP is secondary, i.e. MCP is the result of a sequential transformation. The absence of dimethylcyclohexane (DMCH) in the benzene:toluene:xylene mixture conversion products suggests that the benzene and xylene conversions additionally involve transalkylation

Automation of the Formation of a Mathematical Formulation of Kinetics for Multistage Chemical Reactions and Numerical Solution to a Direct Problem

Introduction. The basis for research, analysis and mathematical optimization of any chemical process is an adequate mathematical model that takes into account the kinetics of the object. Kinetic analysis is a challenge in chemical technology, since it allows for optimizing synthesis processes and predicting their efficiency. Numerous chemical processes involve several stage reactions. For successful design and optimization, a mathematical model that describes each stage is needed. Creating such a model manually can be time-consuming and costly, since it requires processing a large amount of information. The modern level of automation makes it possible to accelerate the obtaining of a mathematical formulation of the kinetics of multistage reactions. In this case, working with data is greatly simplified, and the probability of making mistakes is reduced. The resulting mathematical model can be applied for further analysis and optimization of the process. The paper considers the industrial reaction of catalytic reforming of gasoline, which occupies an important place in the modern scheme of oil refining, since it is a source of high-octane components of commercial gasolines and individual aromatic hydrocarbons. This process is characterized by the participation of a large number (up to 300) of various hydrocarbons, a change in the number of moles, and non-isothermality in it. Mathematical modeling of such processes involves detailing the stages to the required level. The detailing of up to 173 stages is considered. In this setting, automation of the formation of a mathematical formulation of kinetics for catalytic reforming of gasoline has not been carried out before. Therefore, the presented work aimed at implementing effective numerical methods and algorithms for automating the building of a mathematical model taking into account kinetics, thermodynamics, and changes in the number of moles.Materials and Methods. The mathematical formulation of the kinetics of multistage reactions was developed on the basis of the mass action law. The kinetic parameters values were taken from literary sources. The direct kinetics problem was solved using algorithms: the Gear method, the Runge-Kutta method of the 4th order, and the scipy.odeint() method of the Python language. The automation concept was implemented using the IDEF0 methodology. The software was written in the Python programming language.Results. A new software was created to automate the process of forming a mathematical model, taking into account the kinetics, thermodynamics, and the volume of the reaction mixture. The program results were presented by the example of catalytic reforming of gasoline. The model implemented the possibility of taking into account the intermediate heating of the mixture in the reactor cascade. Numerical values of temperature changes corresponding to industrial data were obtained.Discussion and Conclusion. The results obtained through modeling chemical transformations in the cascade of gasoline catalytic reforming reactors confirmed the exothermic nature of the reaction. The developed software product provides displaying changes in the concentrations of reactants, as well as temperature variations in the reactor, and it can be used in scientific research organizations for the analysis of multistage catalytic processes. The results of the reaction kinetics modeling will be used in the subsequent optimization of the process conditions in production.

Carbon isotopic compositions of mono-, di-, tri-aromatics provide insights into the source of sulfur-rich crude oils in the Huanghekou Depression, Bohai Bay Basin

The stable carbon isotope compositions (δ13C) of individual aromatic hydrocarbons have been analyzed in sulfur-rich and sulfur-lean crude oils from the Huanghekou depression, Bohai Bay Basin. The δ13C values of individual aromatic hydrocarbons, including alkylbenzenes, alkylnaphthalenes, alkylphenanthrenes, alkylfluorenes and alkyldibenzothiophenes, are reported. The main aims are to find out the origin of these oils and their relationship to paleoclimate. The distribution of aromatic hydrocarbons and maturity parameters show the oils all stay in the low-mature to mature stage. Meanwhile, aromatic hydrocarbons are mainly derived from the diagenetic/catagenetic origin. The δ13C values for 1,2,4-trimethylbenzene (−30.7‰ to −28.8‰) and 1,2,3,4-tetramethylbenzene (−32.4‰ to −26.3‰) indicate the algae-derived organic matter for alkylbenzenes. Some isomers, such as 1,7-+1,3-+1,6-dimethylnaphthalene, 1,2,5-trimethylnaphthalene, 1,2,5,6-+1,2,3,5-tetramethylnaphthalene, 1,10- + 1,3- + 3,10- + 3,9-dimethylphenanthrenes, 1,6- + 2,9- + 2,5- dimethylphenanthrenes and 4,9- + 4,10- + 1,9- dimethylphenanthrenes show isotopic depletion (−34.9‰ to −25.2‰), indicating the major contribution of algae for these compounds. Meanwhile, isotopically depleted (−33.6‰ to −26.7‰) alkyldibenzothiophenes represent the algae input. δ13C values for mainly algae-derived naphthalene to trimethylnaphthalenes of sulfur-rich oils are more enriched than those of sulfur-lean oil, with the most significant difference of 4.4‰, indicating that the aridity of the environment and stratified water column result in the enrichment in 13C.

STABILITY OF PHYTOCENOSES IN OIL-PRODUCING REGIONS

The only real way to deal with the consequences of oil and oil products spills is a complex of works, including mechanical or physico-chemical removal of spilled oil products with subsequent purification of the remaining oil in the soil by biological methods using phytoremediation with oil-oxidizing plants. One of the stages of the study of hydrocarbon-oxidizing plants before their introduction into the environment for remediation of contaminated sites is the study of the process of degradation of pollutants in model soil systems. Model experiments on cleaning and restoration of soils after their contamination with oil and oil products by plant biomass were studied. Oil samples from the Tengiz field were taken. During the experiments, the indicator of the total amount of biomass, as well as the oil content in the soil, was controlled. To correctly assess the participation of plant raw materials in the destruction of oil, experiments were carried out using non-sterile soils. Among other plant cultures, the most degrading activity was shown by plant cultures of the genus Fabaceae, which led to an increase in growth in the soil environment by an average of 7 sm in 20 days. This is observed for plants with oil concentrations of 3, 6 and 9 g. The results of physical and chemical analyses of phytoremediation products of crude oil, petroleum products and individual aromatic hydrocarbons can be important in microbiological and chemical studies with geobotanical indicators that allow analyzing the mechanism of action of biomass in the process of phytoremediation in the disposal of oil waste that pollutes the environment. The available data on the effect of petroleum hydrocarbons on plants are very contradictory. The species diversity of plants capable of growing on oil-contaminated soils has not been sufficiently studied. Knowledge of the degree of resistance of plants to hydrocarbon pollution is necessary to address issues related, on the one hand, to the possibility of their cultivation on contaminated soil, and on the other - to use for the restoration of disturbed soil fertility. In connection with the above, it is of great scientific and practical interest to study the effect of various doses of oil on changes in vegetation cover, soil properties and assessment of their phytotoxicity, which together determines the relevance of the stated topic.

Hich-octane gasoline production processes using catalysts containing platinum

The catalytic reforming process is designed to increase the detonation resistance of gasolines and to obtain individual aromatic hydrocarbons, mainly benzene, toluene, xylenes - petrochemical feedstocks. It is important to obtain a cheap hydrogen-containing gas in the process for use in other hydrocatalytic processes. The importance of catalytic reforming processes in oil refining increased significantly in the 1990s. due to the need to produce unleaded high-octane gasoline.

Hich-octane gasoline production processes using catalysts containing platinum

The catalytic reforming process is designed to increase the detonation resistance of gasolines and to obtain individual aromatic hydrocarbons, mainly benzene, toluene, xylenes - petrochemical feedstocks. It is important to obtain a cheap hydrogen-containing gas in the process for use in other hydrocatalytic processes. The importance of catalytic reforming processes in oil refining increased significantly in the 1990s. due to the need to produce unleaded high-octane gasoline.

INVESTIGATION OF PETROLEUM FORM NEW WELLS OF EASTERN GEORGIA


 
 
 
 Investigation of new wells of Satskhenisi oil (#7, #11, #12, #13, #14) and Manavi oil (#11, #12) was carried out. By IR spectroscopy it was established that Satskhenisi oil belonged to naphtheno-aromatic type and Manavi oil – to paraffinic type of oils. According to distribution of trace elements V, Fe, Ni, Co, Mo, Cu, Pb, Sn, Zn, Sr, Ba, Ti and the ratio V/Ni <1, these oils refer to tertiary types of oils, which is explained by conditions of accumulation and geochemical transformation of the original organic compounds.Using simulation chromatographic distillation of Manavi oil from the #12 well were obtained naphtha and diesel fractions. In naphtha by method of gas-liquid chromatography were identified individual paraffinic, naphthenic and aromatic hydrocarbons and in diesel fraction – individual n-paraffinic hydrocarbons.By low content of sulfur, tar-asphaltene compounds and high yield of light fractions, Satskhensi and Manavi crude oils are high-quality raw material for production of commercial oil products for energy purposes.
 
 
 

ИССЛЕДОВАНИЕ СКВАЖИН НОВЫХ МЕСТОРОЖДЕНИЙ МАНАВСКОЙ НЕФТИ


 
 
 
 An investigation of oils from new wells of Manavi oil deposit was carried out. Physical and chemical and geochemical parameters, as well as functional groups were determined by IR spectrometry. Using simulative chromatographic distillation of oil from the #12 well naphtha 35-180 °C and diesel fractions were obtained. Individual paraffinic, naphthenic and aromatic hydrocarbons were identified in naphtha by gas chromatographic method and distribution of individual n-paraffinic hydrocarbons in urea concentrate was determined in diesel fraction. The results of the investigation show that due to low content of sulfur, tar- asphaltenic compounds and high yield of light fractions the Manavi oil can be recognized as a high quality paraffinic type of oil. Physical and chemical characteristics, chemical nature and high yield of light fractions outline a good perspective for usage of Manavi deposit oil as a raw material for production of commodity petroleum products like high quality organic solvents, aviation and diesel fuels and various petroleum oils.
 
 
 

A preliminary effort to reduce carcinogenic polycyclic aromatic hydrocarbons from diesel exhaust by using different blends of diesel and synthesized Biodiesel

In the present investigation, an attempt for the reduction of six hazardous air Pollutants (HAPs) from diesel exhaust by different blends of diesel and biodiesel has been made. The synthesis of biodiesel has been done from Jetrofa, Linseed Castor and Karanja oils which are commonly used in the Indian market. Blending of diesel with biodiesel was done in different ratios (20 to 40 %) for the estimation of carcinogenic HAPs from the exhaust of a Honda engine (EBK 2010AC Model). The order of HAPs emission from engine exhaust by using diverse blends were Diesel>Jatropha-diesel>Linseed-diesel>Castor-diesel> Karanja-diesel. The maximum reduction of HAPs was established in the following ratio 40% (Biodiesel):60% (Diesel). B(a)P and Chrysene were the two individual aromatic hydrocarbons (AHCs) found in higher concentration in almost all blending fuels, ranging between 50 ng/µl to 101.1 ng/µl. The emission of almost all AHCs reduces by Blending of Diesel with Biodiesel. This was the first comprehensive information which showed the reduction of carcinogenic pollutants from diesel exhaust.

Catalytic fast co-pyrolysis of biomass and fusel alcohol to enhance aromatic hydrocarbon production over ZSM-5 catalyst in a fluidized bed reactor

In order to enhance aromatic hydrocarbon production, catalytic fast co-pyrolysis (co-CFP) of corn stover and fusel alcohol is conducted with ZSM-5 catalyst in a fluidized bed reactor. Effects of co-CFP temperature, catalyst loading and mass ratio of fusel alcohol to biomass on aromatic hydrocarbon yields are investigated and the experimental results show that bio-derived aromatic hydrocarbons can be formed through Diels-Alder cycloaddition and catalyst-induced hydrocarbon pool. It is found that co-CFP temperature of 550 °C results in the maximum aromatic hydrocarbon yield and the carbon and hydrogen yields of individual and total aromatic hydrocarbons increase dramatically with an elevated catalyst loading amount. Additionally, an apparent synergy between biomass and fusel alcohol is observed during co-CFP. With the consideration of aromatic hydrocarbon yields in bio-oil, the mass ratio of fusel alcohol to biomass of 1:1 in the blends is the best option. Moreover, isotopic labeling technique is utilized to unearth the origin of carbon and hydrogen in aromatic hydrocarbons, and the results demonstrate that carbon and hydrogen atoms from both feedstocks can coexist in the individual aromatic hydrocarbon and make up the targeted products during co-CFP of the blends.

Coliform Bacteria for Bioremediation of Waste Hydrocarbons.

Raw, domestic sewage of Kuwait City contained about 106 ml−1 colony forming units of Enterobacter hormaechei subsp. oharae (56.6%), Klebsiella spp. (36%), and Escherichia coli (7.4%), as characterized by their 16S rRNA-gene sequences. The isolated coliforms grew successfully on a mineral medium with crude oil vapor as a sole source of carbon and energy. Those strains also grew, albeit to different degrees, on individual n-alkanes with carbon chains between C9 and C36 and on the individual aromatic hydrocarbons, toluene, naphthalene, phenanthrene, and biphenyl as sole sources of carbon and energy. These results imply that coliforms, like other hydrocarbonoclastic microorganisms, oxidize hydrocarbons to the corresponding alcohols and then to aldehydes and fatty acids which are biodegraded by β-oxidation to acetyl CoA. The latter is a well-known key intermediate in cell material and energy production. E. coli cells grown in the presence of n-hexadecane (but not in its absence) exhibited typical intracellular hydrocarbon inclusions, as revealed by transmission electron microscopy. Raw sewage samples amended with crude oil, n-hexadecane, or phenanthrene lost these hydrocarbons gradually with time. Meanwhile, the numbers of total and individual coliforms, particularly Enterobacter, increased. It was concluded that coliform bacteria in domestic sewage, probably in other environmental materials too, are effective hydrocarbon-biodegrading microorganisms.

Influence of thermal maturity on carbon isotopic composition of individual aromatic hydrocarbons during anhydrous closed-system pyrolysis

Anhydrous closed-system pyrolysis experiments were conducted on the pure alkyl naphthalenes, n-alkanes and three crude oils at the highly to over mature stage in order to investigate compositional and isotopic changes of individual aromatic hydrocarbons during laboratory maturation. On the whole, aromatic hydrocarbons have better thermal stability than n-alkanes. While the carbon isotopic composition of substituted aromatic hydrocarbons exhibits a positive correlation with increasing thermal maturity, there is no significant fractionation in the carbon isotopic composition of unsubstituted aromatic hydrocarbons. This finding suggests that the carbon isotopic distribution of unsubstituted aromatic hydrocarbons can be used as an effective tool for oil-oil and oil-source correlation, especially for highly-over mature fields.

Nanoheterogeneous catalysis: Definition, state, and research prospects (Review)

This review is concerned with the analysis of nanoheterogeneous catalysis (catalysis in heterogeneous-dispersed systems with nanosized particles of the dispersed phase) in the hydroconversion of a vacuum distillation residue, hydrogenation of individual aromatic hydrocarbons and technical mixtures, and Fischer–Tropsch synthesis. For nanoheterogeneous catalysis, in addition to factors that are typical for heterogeneous catalysis, important factors are the size effect, the all-round accessibility of catalytically active species to reagents, the absence of a porous structure, a high efficiency of heat transfer in the dispersion medium, and an extremely low mass concentration of the catalyst in the suspension reactor (0.05–0.5%) at a high concentration of nanoparticles per reactor volume unit (1013–1015 particles per cubic centimeter). A fine tuning of catalytic processes may be performed in nanoheterogeneous catalysis via a change in the morphology, size, and structure of nanoparticles and variation in their concentration in a suspension reactor. In many cases, the aggregation of nanoparticles accompanied by the formation of nanoaggregates may become the decisive factor for the final outcome of the test reaction and special efforts are needed to stabilize the suspension of catalytically active particles. Technologies based on catalysis by nanosized particles of the dispersed phase have undergone benchmark and pilot tests and are entering the period of wide implementation in the hydroconversion of oil vacuum distillation residue and partially in the Fischer–Tropsch synthesis.

The distribution characteristic and its significance of compound specific isotopic composition of aromatic hydrocarbon from marine source rock and oil in the Tarim Basin, western China

Aromatic hydrocarbons are generally main distillation of crude oil and organic extract of source rocks. Bicyclic and tricyclic aromatic hydrocarbons can be purified by two-step method of chromatography on alumina. Carbon isotopic composition of individual aromatic hydrocarbons is affected not only by thermal maturity, but also by organic matter input, depositional environment, and hydrocarbon generation process based on the GC-IRMS analysis of Upper Ordovician, Lower Ordovician, and Cambrian source rocks in different areas in the Tarim Basin, western China. The subgroups of aromatic hydrocarbons as well as individual aromatic compound, such as 1-MP, 9-MP, and 2,6-DMP from Cambrian-Lower Ordovician section show more depleted 13C distribution. The δ13C value difference between Cambrian-Lower Ordovician section and Upper Ordovician source rocks is up to 16.1‰ for subgroups and 14‰ for individual compounds. It can provide strong evidence for oil sourc correlation by combing the δ13C value and biomarker distribution of different oil and source rocks from different strata in the Tarim Basin. Most oils from Tazhong area have geochemical characteristics such as more negative δ13C9-MP value, poor gammacerane, and abundant homohopanes, which indicate that Upper Ordovician source rock is the main source rock. In contrast, oils from Tadong area and some oils from Tazhong area have geochemical characteristics such as high δ13C9-MP value, abundant gammacerane, and poor homohopanes, which suggest that the major contributor is Cambrian-Lower Ordovician source rock.

Computerized optimization of flows and temperature gradient in flow modulated comprehensive two-dimensional gas chromatography

Informational entropy and syentropy percent were used to optimize the flows in the first (1D) and in the second (2D) dimension (1Fm and 2Fm, respectively) as well as the temperature program rate (r) for the flow modulated GC×GC-FID separation of C6–C12 aromatic hydrocarbons in a low boiling petrochemical sample. The separations were performed on a column series consisting of a 25m×0.25mm i.d.×0.2μm df of the polar ionic liquid SLB-IL 100 (1,9-di(3-vinylimidazolium)nonane bis(trifluoromethylsulfonyl)imide) in the first dimension and 5m×0.25mm i.d.×0.25μm df apolar HP-5MS (5% phenyl-95% methylpolysiloxane) in the second dimension. A dependence of a distribution of individual aromatic hydrocarbons in the 2D retention plane on the carrier gas flows (1Fm, and 2Fm,) and temperature gradient (r) was examined in this study. It was found that informational entropy and synentropy percent are advantageous criteria to characterize the distribution of peaks in the 2D retention plane. Maximum informational entropy and synentropy percents correspond to the maximum distribution of C6–C12 aromatic hydrocarbons in the corresponding 2D retention plane gained by the given separation using optimized values of individual carrier gas column volume flows and the temperature rate at the temperature programmed GC×GC separations.

On the use of ionic liquid capillary columns for analysis of aromatic hydrocarbons in low-boiling petrochemical products by one-dimensional and comprehensive two-dimensional gas chromatography

One-dimensional and comprehensive two-dimensional flow modulated gas chromatography with simultaneous flame ionization and mass spectrometric detection were applied for the identification and quantification of benzene, toluene, ethyl benzene and xylenes (BTEX) as well as of all C9–C11 aromatic hydrocarbons in the low-boiling petroleum products gasoline, reformate and fluid catalytic cracking (FCC) samples. GC×GC experiments were performed on two reversed phase polarity column sets namely SLB-IL100 (25m×250μm i.d.×0.2μm df)+HP-5MS (5m×250μm i.d.×0.25μm df) and SLB-IL111 (30m×250μm i.d.×0.2μm df)+HP-5MS (5m×250μm i.d.×0.25μm df). The one-dimensional GC experiments were carried out on the same ionic liquid columns. The most powerful method is GC×GC on the SLB-111+HP-5MS column combination. Quantitative analysis of individual aromatic hydrocarbons (C6–C11) present in gasoline, reformate and fluid catalytic cracking (FCC) samples was performed by GC×GC-FID using the internal normalization method. Mass spectra obtained by GC×GC-qMSD were used for identification of the aromatic hydrocarbons in these samples.

Sustained induction of cytochrome P4501A1 in human hepatoma cells by co-exposure to benzo[a]pyrene and 7H-dibenzo[c,g]carbazole underlies the synergistic effects on DNA adduct formation

To gain a deeper insight into the potential interactions between individual aromatic hydrocarbons in a mixture, several benzo[a]pyrene (B[a]P) and 7H-dibenzo[c,g]carbazole (DBC) binary mixtures were studied. The biological activity of the binary mixtures was investigated in the HepG2 and WB-F344 liver cell lines and the Chinese hamster V79 cell line that stably expresses the human cytochrome P4501A1 (hCYP1A1). In the V79 cells, binary mixtures, in contrast to individual carcinogens, caused a significant decrease in the levels of micronuclei, DNA adducts and gene mutations, but not in cell survival. Similarly, a lower frequency of micronuclei and levels of DNA adducts were found in rat liver WB-F344 cells treated with a binary mixture, regardless of the exposure time. The observed antagonism between B[a]P and DBC may be due to an inhibition of Cyp1a1 expression because cells exposed to B[a]P:DBC showed a decrease in Cyp1a1 mRNA levels. In human liver HepG2 cells exposed to binary mixtures for 2h, a reduction in micronuclei frequency was also found. However, after a 24h treatment, synergism between B[a]P and DBC was determined based on DNA adduct formation. Accordingly, the up-regulation of CYP1A1 expression was detected in HepG2 cells exposed to B[a]P:DBC. Our results show significant differences in the response of human and rat cells to B[a]P:DBC mixtures and stress the need to use multiple experimental systems when evaluating the potential risk of environmental pollutants. Our data also indicate that an increased expression of CYP1A1 results in a synergistic effect of B[a]P and DBC in human cells. As humans are exposed to a plethora of noxious chemicals, our results have important implications for human carcinogenesis.

Stable carbon isotopic compositions of individual aromatic hydrocarbons as source and age indicators in oils from western Australian basins

The present study aims to establish the factors controlling the stable carbon isotopic compositions (δ 13C) of individual aromatic hydrocarbons analysed by compound specific isotope analysis (CSIA) in crude oils from western Australian petroleum basins of varying age and facies type. This paper reports δ 13C values of individual aromatic hydrocarbons, like alkylbenzenes, alkylnaphthalenes, alkylphenanthrenes and methylated biphenyls. The main aims are to confirm the origin (source) and age of these oils based on CSIA of selected aromatic compounds and to understand why the Sofer plot is ineffective in establishing the source of western Australian petroleum systems. The bulk δ 13C of saturated and aromatic hydrocarbon fractions of crude oils have been previously used to differentiate sources, however, many Australian crude oils are not classified correctly using this method. The oils were classified as marine by the δ 13C values of individual aromatic compounds and as terrigenous based on the bulk δ 13C data (Sofer plot). The oils where the δ 13C values of 1,6-DMN and 1,2,5-TMN isomers are most negative are indicative of a marine source, whereas oils with a less negative values for the 1,6-DMN and 1,2,5-TMN isomers are derived from marine source rocks that contain a significant terrigenous component. Similarly, oils with the least negative δ 13C values for the 1-MP and 1,9-DMP isomers reflect varying inputs of terrigenous organic matter to the their marine source rocks. Plots of P/DBT and Pr/Ph concentration ratios versus δ 13C values of DMP, 1,6-DMN, 1,2,5-TMN, 1-MP and 1,9-MP are constructed to establish the relative amount of terrigenous organic matter contributing to the source rock of a series of marine oils. The ratios of P/DBT and Pr/Ph plotted against the δ 13C values of the aromatic isomers (such as 1,6-DMN, 1,2,5-TMN, 1-MP and 1,9-MP) provide a novel and convenient way to discriminate crude oils derived from different source rocks that contain varying amounts of marine and terrigenous organic matter.

PlANT-ASSOCIATED BACTERIA AS TOOLS FOR THE PHYTOREMEDIATION OF OILY NITROGEN-POOR SOILS

The rhizospheres and phyllospheres of peas, beans, tomatoes, and squash raised in a desert sand soil mixed with 0.5% crude oil were rich in oil-utilizing bacteria and accommodated large numbers of free-living diazotrophic bacteria, with potential for hydrocarbon utilization. According to their 16S rRNA-sequences, the cultivable oil-utilizing bacteria were affiliated with the following genera, arranged in decreasing frequency: Bacillus, Ochrobactrum, Enterobacter, Rhodococcus, Arthrobacter, Pontola, Nocardia, and Pseudoxanthomonas. Diazotrophic isolates were affiliated with Rhizobium, Bacillus, Rhodococcus, Leifsonia, Cellulosimicrobium, Stenotrophomonas, Kocuria, Arthrobacter, and Brevibacillus. The crude oil–utilizing and diazotrophic isolates grew, with varying growth intensities, on individual aliphatic (C8 to C40) and aromatic hydrocarbons, as sole sources of carbon and energy. Quantitative gas liquid chromatographic measurements showed that representative bacterial isolates eliminated pure n-hexadecane, n-decosane, phenanthrene, and crude oil from the surrounding liquid media. Cultivation of oily sand–soil samples with any of the four tested crops led to enhanced oil degradation in that soil, as compared with the degradation in uncultivated oily sand–soil samples.