Distribution Of Aliphatic Hydrocarbons Research Articles

Gas–particle concentrations and distribution of aliphatic hydrocarbons, PAHs, PCBs and PCDD/Fs in the atmosphere of Athens (Greece)

Air samples were collected at the urban center, a background site, and the adjacent coastal area of the metropolitan area of Athens during July 2000. Gas and particle phase concentrations of aliphatic hydrocarbons, α, β-hopanes, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and 2,3,7,8-substituted polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) were identified and measured. Total concentrations of aliphatic hydrocarbons, ranged between 943.0 ng m −3 (urban site) and 947.1 ng m −3 (coastal area) in the gas and from 141.8 ng m −3 (coastal site) up to 469.0 ng m −3 (urban center) in the particulate phase. The total concentration of α, β-hopanes (12 homologues) in the urban area was ca. 0.2 ng m −3 in the gas and 1.0 ng m −3 in the particulate phase. Total PAH concentrations (∑PAHs of 20 members) ranged from 3.5 ng m −3 (background site) to 26.0 ng m −3 (urban center) in the gas and from 1.3 ng m −3 (coastal area) up to 5.0 ng m −3 (urban center) in the particulate phase. The total concentration of PCBs (∑PCBs of 38 congeners) in the gas plus the particulate phase of the atmosphere ranged from 80.5 pg m −3 (background site) up to 348.6 pg m −3 (urban center) and the corresponding concentration of PCDD/Fs ranged from 166.6 fg m −3 (background site) up to 701.5 fg m −3 (urban center), respectively. Gas–particle partition coefficients K p of n-alkanes, PAHs, PCBs and PCDD/Fs were well correlated ( R 2=0.50–0.99) with the sub-cooled liquid vapor pressure P L o . The average slopes m r of log K p versus log P L o for n-alkanes (−0.46) and PCBs (−0.44) were low compared to other urban areas. The corresponding m r values for PAHs (−0.57), PCDDs (−0.78) and PCDFs (−0.75) are comparable to those obtained in other urban areas.

Chemosystematic and microstructural investigations on Carboniferous seed plant cuticles from four North American localities

The cuticles of different Late Carboniferous plants – Cordaitales from Lone Star Lake, Kansas, USA; Cordaitales, and pteridosperms ( Neuralethopteris and Eusphenopteris) from Joggins, NS, Canada; and conifers of the genus Walchia from Garnett and Hamilton, both in Kansas, USA – have been isolated from rock and examined by electron microscopy and pyrolysis–gas chromatography–mass spectrometry. Cuticles are preserved as sheets from larger leaves or as entire cuticle envelopes from smaller, scale-like leaves. Each cuticle has morphology diagnostic of the parent plant group reflected in external appendages and/or external/internal patterns indicative of the arrangement of underlying epidermal cells. All cuticles have amorphous ultrastructure in thin section. All cuticle pyrolysates reveal a highly aliphatic character, however there are differences in the distribution and relative abundance of aliphatic hydrocarbons between the different genera. The pyrograms of the two Cordaites and the two Walchia are similar to one another but distinct from pyrograms of other seed plant cuticles, including those from the same localities. Hence, cuticles retain some chemosystematic signature. However, there are no obvious closer similarities between the cordaites and conifers ( Walchia) than between these and the pteridosperms ( Neuralethopteris, Eusphenopteris) in spite of the evolutionary relationship of cordaites and conifers as sister taxa.

Effects of biodegradation on Australian Permian coals

Permian coals from Blackwater, Poitrel and Moura (Bowen Basin, Queensland) have been extracted and characterised by detailed organic geochemical techniques. A variety of source-related aliphatic and aromatic biomarker parameters indicate that these coals from three different locations are similar in terms of organic matter type and palaeoenvironment of deposition. The hydrocarbons extracted from these coals appear to have been generated from predominantly plant-derived organic matter deposited in a fluvio-deltaic environment. Moderately high Pr/Ph ratios, the high proportion of C 29 steranes and very low sterane to hopane ratios are indicative of their largely terrestrial source. Molecular maturity parameters derived from aliphatic and aromatic biomarkers corroborate a measured maturity of 1.0–1.1% R o for these medium volatile bituminous coals. The aliphatic and aromatic hydrocarbon distributions in these coals also allow their differentiation into two groups: biodegraded Moura coals and non-degraded Blackwater and Poitrel coals. Comparison of various compound ratios from the degraded and non-degraded coals indicate the dependence of susceptibility to biodegradation on precise molecular structures. Major aromatic compound classes in coals, generally regarded as being more resistant, may be microbially altered before branched/cyclic alkanes are affected and even before the n-alkanes are completely removed. As reported in crude oils, susceptibility to biodegradation of aromatic hydrocarbons decreases with increasing number of aromatic rings and with increasing number of alkyl substituents. Furthermore, alkylnaphthalenes with 1,6-dimethyl substitution patterns are more susceptible to degradation than other alkylnaphthalene isomers. This study reveals that biodegradation may alter the hydrocarbon composition of coals in a similar way to that observed in crude oils or oil spills, except that aromatic hydrocarbons are altered relatively earlier than aliphatic hydrocarbons in coals compared to oils.

Sources, Distribution, and Water Column Processes of Aliphatic and Polycyclic Aromatic Hydrocarbons in the Northwestern Black Sea Water

Aliphatic and aromatic hydrocarbons have been determined in (28 samples) suspended particulate matter (>0.7 μm) collected at subsurficial seawater and three vertical profiles in a transect from the continental shelf, slope, and deep basin (15 samples) of the western Black Sea. The dissolved phase (<0.7 μm) was collected at subsurficial and in the redoxcline (6 subsurficial and 5 deeper). The highest concentrations of hydrocarbons were detected in the Danube, Dnieper, and Dniester River Estuaries and other point sources of pollution located offshore Romania and Bulgaria where oil production and refining is carried out (i.e., Constantza, Varna). Concentrations of hydrocarbons decreased with increasing distance from the coast, but relatively high concentrations were found at the open stations where the particulate organic carbon (POC) is higher. Fossil PAHs are predominant in the coastal stations, and the unresolved complex mixture (UCM) of aliphatic hydrocarbons is predominantly of a fossil common origin ac...

Distribution and Origin of Hydrocarbons in Water and Sediment in São Sebastião, SP, Brazil

This study describes the dissolved/dispersed petroleum hydrocarbons (DDPH) in surface water and the origin and distribution of aliphatic and aromatic hydrocarbons in samples from the surface bottom sediments. The main objective was to verify the anthropogenic contribution on the adjacent inner shelf off São Sebastião, taking into account the distribution of hydrographic properties and knowledge of the main circulation. The DDPH concentration range of the 20 samples was from 0.35 to 2.50 μ g.L −1, characterizing this region as slightly affected by the contribution of petroleum hydrocarbons. Considering sediment hydrocarbon results, sites located in the inner shelf were divided into three groups: one with mainly biogenic hydrocarbons, a second one with biogenic and petroleum hydrocarbons and a third with significant contribution of petroleum hydrocarbons. These results show an influence of human activities in the São Sebastiõ Channel on the surrounding area of the inner shelf.

99/00182 A simple estimation of shale oil content by thermogravimetry

The organic matter rich Oligocene Menilite black shales and mudstones are widely distributed in the Carpathian Overthrust region of southeastern Poland and have excellent hydrocarbon generation potential, according to TOC, Rock-Eval, and petrographic data. Extractable organic matter was characterized by an equable distribution of steranes by carbon number, by varying amounts of 28,30-dinor-hopane, 18α(H)-oleanane and by a distinctive group of C24 ring-A degraded triterpanes. The Menilite samples ranged in maturity from pre-generative to mid-oil window levels, with the most mature in the southeastern portion of the study area. Carpathian petroleum samples from Campanian-Oligocene sandstone reservoirs were similar in biomarker composition to the Menilite rock extracts. Similarities in aliphatic and aromatic hydrocarbon distributions between petroleum asphaltene and source rock pyrolyzates provided further evidence genetically linking Menilite kerogens with Carpathian oils.

Aliphatic and polycyclic aromatic hydrocarbons in Black Sea sediments

Concentrations of aliphatic hydrocarbons (AHC) in sediments of the Black Sea ranged from 153,000 ng g−1 dw near the mouth of the Danube River to about 10,000 ng g−1 dw in abyssal plain sediments. Compound distributions were dominated by long-chain n-alkanes except at the Danube station where a significant petrogenic component with an unresolved complex mixture was also present. Polycyclic aromatic hydrocarbon (PAH) concentrations ranged from 1,250 ng g−1 dw to about 200 ng g−1 dw at the same locations and compound distributions were dominated by PAH of pyrolytic origin. The flux of hydrocarbons to the central Black Sea sediments over the past 25 years is estimated to be ~ 580 μg AHC m−2 yr−1 and ~ 80 μg PAH m−2 yr−1. Long-range aeolian transport is invoked as the primary mechanism for delivering terrigenous higher plant AHC and pyrogenic PAH in abyssal Black Sea sediments although petrogenic hydrocarbons and retene appear to be delivered via fluvial transport and as a result are preferentially deposited in sediments along the continental margin. Analysis of a sediment core showed a rapid decrease in AHC and PAH concentrations with increasing depth in the sediment, reaching background levels of about 1000 ng g−1 dw and 10 ng g−1 dw, respectively, by about 4 cm depth or about 150 years BP. AHC fluxes in these sediments deposited before the industrial revolution were ~ 50 μg m−2 yr−1, PAH fluxes were ~ 0.5 μg m−2 yr−1. Differences between the distributions of AHC and PAH in surface sediments and the core sediments indicate an uncoupling of the source and transport processes affecting various components of the two hydrocarbon classes.

Organic geochemistry and petrology of oil source rocks, Carpathian Overthrust region, southeastern Poland—implications for petroleum generation

The organic matter rich Oligocene Menilite black shales and mudstones are widely distributed in the Carpathian Overthrust region of southeastern Poland and have excellent hydrocarbon generation potential, according to TOC, Rock-Eval, and petrographic data. Extractable organic matter was characterized by an equable distribution of steranes by carbon number, by varying amounts of 28,30- dinor-hopane, 18α(H)-oleanane and by a distinctive group of C 24 ring-A degraded triterpanes. The Menilite samples ranged in maturity from pre-generative to mid-oil window levels, with the most mature in the southeastern portion of the study area. Carpathian petroleum samples from Campanian-Oligocene sandstone reservoirs were similar in biomarker composition to the Menilite rock extracts. Similarities in aliphatic and aromatic hydrocarbon distributions between petroleum asphaltene and source rock pyrolyzates provided further evidence genetically linking Menilite kerogens with Carpathian oils.

Aliphatic and Polycyclic Aromatic Hydrocarbons and Sulfur/Oxygen Derivatives in Northwestern Mediterranean Sediments: Spatial and Temporal Variability, Fluxes, and Budgets

The spatial and temporal distribution of aliphatic and polycyclic aromatic hydrocarbons (PAHs) and sulfur/oxygen derivatives in sediments from the NW Mediterranean basin were investigated. Along the Continental Shelf and slope, an unresolved complex mixture (UCM) of aliphatic hydrocarbons and alkylated PAHs, indicative of petrogenic inputs, were predominant. Long-chain n-alkanes derived from terrestrial plant waxes (n-C27, n-C29, and n-C31) and parent PAHs, which are typical of high-temperature combustion processes, were evenly distributed in the whole basin and largely prevailing in the deepest areas. Perylene, a geochemically derived PAH, was found highly abundant in the areas influenced by river discharges. The highest anthropogenic hydrocarbon inputs were found near the cities of Marseille and Barcelona, being the contribution of the Rhone River ca. 25 times higher than that of the Ebro. Fluxes of PAHs in the deep basin were consistent with a predominant atmospheric input. These results account for an...

CHEMICAL ANALYSIS OF HIGH ASH BRAZILIAN COAL TAR. 3. HYDROCARBON CHARACTERIZATION

Abstract In this paper we show the total analysis of the hydrocarbon fractions obtained from the chromatographic fractionation of a coal tar cut, previously described. All fractions were analyzed by Gas Chromatography coupled to Mass Spectrometry using a non-polar capillary column. A group-type distribution of aliphatic, olefins and monoaromatic hydrocarbons was found in the first three fractions obtained (I, II and III). In fractions IV and V polyaromatics with two or more condensed rings were founded. Many of these hydrocarbons are recognized to be carcinogenic and mutagenic, including pyrene, chrysene and others.

The galactic distribution of aliphatic hydrocarbons in the diffuse interstellar medium.

The infrared absorption feature near 2950 cm-1 (3.4 micrometers), characteristic of dust in the diffuse interstellar medium (ISM), is attributed to C-H stretching vibrations of aliphatic hydrocarbons. We show here that the strength of the band does not scale linearly with visual extinction everywhere, but instead increases more rapidly for objects near the center of the Galaxy, a behavior that parallels that of the Si-O stretching band due to silicate materials in the diffuse ISM. This implies that the grains responsible for the diffuse medium aliphatic C-H and silicate Si-O stretching bands are different from those responsible for much of the observed visual extinction. It also suggests that the distribution of the carbonaceous component of the diffuse ISM is not uniform throughout the Galaxy, but instead may increase in density toward the center of the Galaxy. The similar behavior of the C-H and Si-O stretching bands suggests that these two components may be coupled, perhaps in the form of silicate-core, organic-mantle grains. Several possible models of the distribution of this material are presented and it is demonstrated that the inner parts of the Galaxy has a carrier density that is 5 to 35 times higher than in the local ISM. Depending on the model used, the density of aliphatic material in the local ISM is found to be about 1 to 2 -CH3 groups m-3 and about 2 to 5 -CH2- groups m-3. These densities are consistent with the strengths of the 2955 and 2925 cm-1 (3.38 and 3.42 micrometers) subfeatures (due to -CH3 and -CH2- groups, respectively) within the overall 2950 cm-1 (3.4 micrometers) band being described by the relations A upsilon/tau(2955 cm-1) = 270 +/- 40 and A upsilon/tau(2925 cm-1) = 250 +/- 40 in the local diffuse ISM.

Seasonally dependent size distributions of aliphatic and polycyclic aromatic hydrocarbons in urban aerosols from densely populated areas

Aerosol samples corresponding to well-defined cold/warm seasons in the atmosphere of Barcelon a have been collected and size-fractionated during stable atmospheric conditions. A predominant hydrocarbon pattern derived from gasoline and diesel vehicular traffic emissions has been identified in most particle fractions. In quantitative terms, these hydrocarbons exhibit a predominant occurrence in the submicron fractions, particularly the <0.5-μm fraction, which is likely characteristic of early aging stages after gas-phase emission of combustion residues to the atmosphere. This predominant occurrence contrasts with the bimodal log-normal distribution of particles found in the city. The seasonal fluctuations of these hydrocarbons reflect a strong decrease in the warm period

Hydrous pyrolysis of crude oil in gold-plated reactors

Crude oils from Iraq and California have been pyrolyzed under hydrous conditions at 200 and 300°C for time periods up to 210 days, in gold-plated reactors. Elemental (vanadium, nickel), stable isotopic (carbon), and molecular ( n-alkanes, acyclic isoprenoids, steranes, terpanes and aromatic steroid hydrocarbons) analyses were made on the original and pyrolyzed oils. Various conventional crude oil maturity parameters, including 20 S/(20 S + 20 R)-24-ethylcholestane ratios and the side-chain-length distribution of aliphatic and aromatic steroidal hydrocarbons, were measured in an effort to assess the modification of molecular maturity parameters in clay-free settings, similar to those encountered in “clean” reservoirs. Concentrations of vanadium and nickel in the Iraq oil decrease significantly and the V/(V + Ni) ratio decreases slightly, with increasing pyrolysis time/temperature. Whole oil carbon isotope ratios remain fairly constant during pyrolysis, as do hopane/sterane ratios and carbon number distribution of 5 α(H),14 α(H),17 α(H),20 R steranes. These latter three parameters are considered maturity-invariant. The ratios of short side-chain components to long side-chain components of the regular steranes [C 21/(C 21 + C 29 R)] and the triaromatic steroid hydrocarbons [C 21/(C 21 + C 28)] vary systematically with increasing pyrolysis time, indicating that these parameters may be useful as molecular maturity parameters for crude oils in clay-free reservoir rocks. In addition, decreases in bisnorhopane/hopane ratio with increasing pyrolysis time, in a clay-free and kerogen-free environment, suggest that the distribution of these compounds is controlled by either differential thermal stabilities or preferential release from a higher-molecular weight portion of the oil.

A statistical approach to the interpretation of aliphatic hydrocarbon distributions in marine sediments

Q-mode factor analysis was used to quantitate the distribution of the major aliphatic hydrocarbon (n-alkanes, pristane, phytane) systems in sediments from a variety of marine environments. The compositions of the pure end members of the systems were obtained from factor scores and the distribution of the systems within each sample was obtained from factor loadings. All the data, from the diverse environments sampled (estuarine (San Francisco Bay), fresh-water (San Francisco Peninsula), polar-marine (Antarctica) and geothermal-marine (Gorda Ridge) sediments), were reduced to three major systems: a terrestrial system (mostly high molecular weight aliphatics with odd-numbered-carbon predominance), a mature system (mostly low molecular weight aliphatics without predominance) and a system containing mostly high molecular weight aliphatics with even-numbered-carbon predominance. With this statistical approach, it is possible to assign the percentage contribution from various sources to the observed distribution of aliphatic hydrocarbons in each sediment sample.

Molecular mass distribution of aliphatic and aromatic hydrocarbons obtained from CO and H2 in the presence of Fe catalysts

It has been demonstrated that together with C1-C6 aliphatic hydrocarbons up to 20% C6-C9 aromatic hydrocarbons are formed from a mixture of CO∶H2 (1∶1) in the presence of 8.2% Fe-4.5% K/Al2O3. A new method for determining the parameter a in the Schultz-Flory equation has been proposed which is applicable to the synthesis of low molecular mass C1-C6 hydrocarbons. It has been shown that the mass fractions of aromatic hydrocarbons are higher than the values expected on the basis of a step-wise mechanism for growth of the hydrocarbon chain.

Accumulation and Distribution of Aliphatic (n‐Nonane), Aromatic (1,2,4‐Trimethylbenzene) and Naphthenic (1,2,4‐Trimethylcyclohexane) Hydrocarbons in the Rat after Repeated Inhalation

The concentrations of the C9 hydrocarbons n-nonane, 1,2,4-trimethylbenzene and 1,2,4-trimethylcyclohexane were measured in rat blood, brain and perirenal fat after exposures to 1000 p.p.m. of the individual compounds. Measurements were made by head space gas chromatography at the end of 12 hr exposures on days 1, 3, 7, 10 and 14 of the exposure periods. The relative concentrations of hydrocarbons in each organ were, brain: n-nonane "trimethylcyclohexane approximately trimethylbenzene, blood: trimethylbenzene "n-C9 greater than trimethylcyclohexane and perirenal fat: trimethylbenzene greater than n-nonane greater than trimethylcyclohexane, showing the widely different distribution properties of the different hydrocarbons. Brain/blood ratios of 11.4, 2.0 and 11.4, and fat/blood ratios of 113, 63 and 135 were found for n-nonane, trimethylbenzene and trimethylcyclohexane, respectively. A marked decrease in biological concentrations of trimethylbenzene and trimethylcyclohexane during the initial phase of exposure indicate that these hydrocarbons are capable of inducing their own metabolic conversion resulting in lower steady state levels. A special attention was made to n-nonane showing the highest concentration in brain concomitantly with a low blood concentration. This observation demonstrate that biological monitoring of occupational exposure by blood measurements not should be performed without knowledge of the distribution properties of the compounds investigated.

Distribution and sources of aliphatic hydrocarbons in fish from the Arabian Gulf

Distribution and sources of aliphatic hydrocarbons in fish from the Arabian Gulf

Vertical distribution of aliphatic and aromatic hydrocarbons in mussels from the Amposta offshore oil production platform (Western Mediterranean)

The qualitative distributions of aliphatic hydrocarbons in mussels adhered to the legs of an oil production platform (Amposta, Western Mediterranean) have evidenced local (diesel oil) and chronic inputs (middle East crude oils) as the main pollutant sources in the area. Quantitative data have shown that aromatic hydrocarbons are selectively accumulated with the age of mussels and are more evenly distributed through the water column. Background concentrations of petrogenic aliphatic hydrocarbons in mussels living in the vicinity of oil platforms have been established in the range of 25–40 ug/g dry weight.

Distribution of aliphatic, aromatic and chlorinated hydrocarbons in mussels from the Spanish Atlantic coast (Galicia). An assessment of pollution parameters

Mussel populations collected in a suite of heavily polluted to non-polluted estuarine systems of the NW Spanish Atlantic Coast (Galicia) have been analyzed for alkanes+alkenes (I), monocyclic aromatics and PCBs (II), and polycyclic aromatics (III). Using GC-FID, GC-ECD, GC-MS and UV-fluorescence, molecular marker identifications and correlation trends of chemical composition parameters have been determined for the assessment of pollution. The results have shown that both the resolved and unresolved components of fractions I and II are predominated by petrogenic hydrocarbons. UV-fluorescence is also useful for the measurement of petroleum contributions in fraction II although a standard better than chrysene should be developed for quantitation. The unresolved hydrocarbons of fraction III correspond to a mixture of petrogenic and pyrolytic sources. Finally, the polychlorobiphenyls do not show any correlation with petrogenic or pyrolytic pollutant sources.

Release of aliphatic, aromatic and sulphur compounds from Kimmeridge kerogen by hydrous pyrolysis: A quantitative study

The results discussed in this paper form part of a larger study aimed at obtaining qualitative and quantitative data on the types and amounts of aliphatic and aromatic hydrocarbons (including biological markers) and sulphur-containing heterocyclic compounds released when kerogens, asphaltenes and the polar fractions of extracted bitumens, and crude oils, are heated in the presence of excess water. Some of the results from the experiments in which Kimmeridge kerogen was heated in the presence of excess water, at times ranging from 7 h to 3 months and at temperatures ranging from 200 to 340°C are reported here. The maximum yield of pyrolysate was obtained in experiments conducted at 330°C for 72 h, and became increasingly aromatic as pyrolysis temperatures increased. Aliphatic hydrocarbon distributions became increasingly oil-like. Interestingly, unsaturated isoprenoid hydrocarbons were present but only in the low temperature reaction mixtures. Quantitative estimates of individual hydrocarbon types showed that with increasing temperatures the n-alkanes were approximately five to tenfold more abundant than the isoprenoid hydrocarbons by that the rate of release of the latter, in the lower temperature work, was greater than for the n-alkanes. The very small amoounts of C 21 + C 22 steranes released increased for all reaction temperatures and with increased heating times; unlike the C 27–C 29 steranes, and hopanes they did not pass through a maximum yield at lower pyrolysis temperatures. Approximately five times more alkylnaphthalenes than phenanthrenes plus anthracenes were released. The most abundant sulphur containing compounds in the pyrolysates were alkylbenzothiophnes and dibenzothiophenes, the former being tenfold more abundant than the latter and almost double the total amount of alkylnaphthalenes produced at high pyrolysis temperatures. Microscopy of all of the kerogen residues indicated that vitrinite-like material had been generated in the heated kerogens and this increased in rank with increased temperatures and times of heating.