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A variety of biomarker and non-biomarker parameters has been used to geochemical characterization of seven crude oils from the Gulf of Suez region of Egypt. The carbon number distribution and the i...

Gas chromatography and combined gas chromatography/mass spectrometry were used to characterize different thiophenic compounds in representative petroleum from the Gulf of Suez. An evaluation of the distribution patterns of these compounds has been used to infer depositional environment and lithology of crude oil source rock and maturity. Ratios involving dibenzothiophenes (DBT) such as DBT/phenanthrene (Phen) and methyldibenzothiophenes (MDBT)/methylphenanthrenes (MPhen) correlated with other biological markers and were used to classify the oils into different source-related types. Type 1 oils with relatively high (DBT/Phen) and (MDBT/MPhen) ratios show marine carbonate depositional setting. Type 2 oils show low (DBT/Phen) and (MDBT/MPhen) ratios and other biomarker features consistent with marine siliciclastic source rocks. On the other hand, type 3 oils have geochemical characteristics intermediate between those of types 1 and 2.

The purpose of this study was to determine the levels, distribution and toxicological potential of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in sewage sludge samples from several WWTPs in the Alexandria area, Egypt. The POPs of interest were 26 PCBs and 16 OCPs. Analyses were performed by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode (GC-MS-SIM) using deuterated organochlorines as internal standards. Total concentrations of OCPs and Σ7 PCBs (ICES) in sludge ranged from 44.2 to 489 μg/kg dw. and 5,600 to 11,000 μg/kg dw., respectively. The highest concentration levels were found for PCBs, HCHs, DDTs, and HCB, in this order. The PCB homologue profiles in sludge samples were dominated by penta- and hexa-chlorinated biphenyls. Seasonal variations were observed for OCPs with higher levels in summer, which reflects more usage in warmer climates. Composite profiles of OCP metabolites indicated new inputs of lindane and technical endosulfan and earlier usage of DDT and technical chlordane. Contamination levels of OCPs and PCBs for Egyptian sludge can be categorized as moderate to high compared to other countries worldwide. The OCP content in none of the samples exceeded limits set by the European Commission for use of sludge in agriculture; while all the concentrations of PCBs in sludge samples were higher by one order of magnitude than the upper limit for land application.

The purpose of this study was to determine concentrations of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in Nile tilapia (Oreochromis niloticus) and Bouri fish (Mugil cephalus) from Lake Qarun, a protected area of Egypt, and evaluate the relative ecological risk of these compounds. Different tissues of the fish species were analyzed for 26 chlorinated pesticides and 29 PCB congeners. Total concentrations (µg/kg wet weight, ww) of OCPs ranged between 1487 and 6217 (mean: 3260) and of PCBs between 9.0 and 61 (mean: 34). The trend of detected organochlorine pollutants was: endrin aldehyde > dieldrin > hexachlorobenzene > PCBs > endrin > 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethanes (DDTs). Heptachlor epoxide; oxy-, cis-, and trans-chlordane; trans-nonachlor; β-hexachlorocyclohexane; δ-hexachlorocyclohexane; and endosulfan I and endosulfan sulfate levels were below the detection limit. The ratios of (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylenes [DDEs] + 1,1-dichloro-2,2-bis...

Organochlorine contamination in the Mediterranean coastal environment of Egypt was assessed based on 26 surface sediments samples collected from several locations on the Egyptian coast, including harbors, coastal lakes, bays, and estuaries. The distribution and potential ecological risk of contaminants is described. Organochlorine compounds (OCs) were widely distributed in the coastal environment of Egypt. Concentrations of PCBs, DDTs, and chloropyrifos ranged from 0.29 to 377 ng g −1 dw, 0.07 to 81.5 ng g −1 dw, and below the detection limit (DL) to 288 ng g −1 dw, respectively. Other organochlorinated pesticides (OCP) studied were 1–2 orders of magnitude lower. OCP and PCBs had higher concentrations at Burullus Lake, Abu Qir Bay, Alexandria Eastern Harbor, and El Max Bay compared to other sites. OCP and PCB contamination is higher in the vicinity of possible input sources such as shipping, industrial activities and urban areas. PCB congener profiles indicated they were derived from more than one commercially available mixture. The ratios of commercial chlordane and heptachlor metabolites indicate historical usage; however, DDT and HCHs inputs at several locations appear to be from recent usage. The concentrations of PCBs and DDTs are similar to those observed in sediments from coastal areas of the Mediterranean Sea. Ecotoxicological risk from DDTs and PCBs is greatest in Abu Qir Bay, Alexandria Harbor, and El-Max Bay.

Two successive degradation steps involving Na 2 Cr 2 O 7 /AcOH and RuO 4 were carried out on a Type II-S kerogen from the Miocene Monterey Formation (California) after pre-saponification of the ester bonds by KOH/MeOH treatment. Detailed gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS) analysis of the soluble acids revealed significant qualitative and quantitative variation of the various types of products obtained from the two different degradation steps. Maleimides (lH-pyrrole-2,5-diones), dominated by Me,Et-maleimide, were the major degradation products released by Na 2 Cr 2 O 7 /AcOH oxidation indicating that their precursors, probably tetrapyrrole pigments, occur ether- as well as sulfur-bound in the kerogen. On the other hand, a scarcely reported homologous series of 2-methyl- n -alkanoic acids (C 8 –C 27 ) was identified as the most prominent series of carboxylic acids obtained after RuO 4 oxidation. The results support the high specificity of the RuO 4 oxidation method in revealing information on the nature of the alkyl chains substituting the aromatic moieties in the kerogen structure and point to the presence of aryl–alkyl ether groups in the kerogen. The significance of the lipid composition of the kerogen is further discussed in terms of biomarker information and their original attachment to the macromolecular structure.

The distribution of free sterols in a sulfur-rich lacustrine sediment of Miocene age deposited in the ancient crater lake of the Nordlinger Ries (southern Germany) was investigated and compared with the corresponding distributions of esterified and kerogen-bound sterols. The three fractions exhibited the same suite of principal sterols, with 4α,24-dimethyl-5α- cholestan-3β-ol, dinosterol and dinostanol displaying the highest concentrations and relative abundances. The distributions of sterols, steroidal ketones, n-alkanols and isoprenoid alcohols suggest a prevalent deposition of autochthonous aquatic organic matter under saline conditions. In particular, the high abundance of 4α,24-dimethyl-5α-cholestan-3-one, dinosterone and dinostanone and the corresponding 4-methyl sterols indicates the importance of dinoflagellate productivity in this former crater lake and its significant contribution to the sedimentary lipids in the Nordlinger Ries sediment. The similarity in structures and relative abundance of the major 4-methyl sterols and the corresponding steroidal ketones suggest that they are biosynthetically linked.

Several series of alkylated phenols were detected for the first time in the extractable bitumens of organic matter-rich sediments from the Nordlinger Ries (southern Germany). Most abundant and significant constituents comprise those with n-octadecyl, n-eicosanyl, phytanyl, and iso-pentadecyl and anteiso-pentadecyl substituents. The structures of these compounds are suggested from mass spectrometric and retention time data and coinjection with synthetic standards. Diagenetic alteration of phenolic algal lipids is suggested as a possible way to the formation of these compounds in the Nordlinger Ries sediments.

Ruthenium tetroxide oxidation was applied to sulfur-rich kerogens from the Nordlinger Ries, southern Germany, to provide complementary structural information about the nature of alkyl substituents attached to aromatic moieties. The oxidation products contained series of straight-chain monocarboxylic acids (C8–C29), α,ω-dicarboxylic acids (C7–C26), isoprenoid acids (C14–C21, except C18), non-isoprenoid branched acids (mainly iso and anteiso C11–C18 acids), 3β-carboxysteroids (C28–C31) and steroid ketones (C27–C30). Furthermore, 4-hydroxy-4,8,12,16-tetramethylheptadecanoic acid γ-lactone, 6,10,14-trimethylpentadecan-2-one, and 10-oxo-n-octadecanoic acid were identified. The oxidation products are discussed in terms of their original contribution to the macromolecular structure. The results support previous suggestions that alkyl–aryl ether groups are present in the kerogen, probably as a result of O-alkylation between phenols and aliphatic precursors. Of particular interest, however, is the identification of a predominant homologous series of 2-methyl n-alkanoic acid methyl esters (C9–C28) in one of the samples. The release of this scarcely reported series of branched acids points toward the specificity of RuO4 oxidation revealing structural information on the alkyl chains substituting the aromatic moieties in the kerogen structure, and implies that some of the bound lipids were contributed by sulfate-reducing bacteria.

Concentrations of Al, As, Ba, Be, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Se, Sn, V and Zn in road dust particles at seven sites in the Delta region have been investigated using atomic absorption spectroscopy (AAS). Results showed that samples were highly contaminated with Cd, Pb, Sn and Zn and moderately contaminated with As, Se, Ba and Cu when compared to the average crustal background concentrations of metals. The output of the principle component analysis revealed that Al, Fe, Be and Mn were predominantly driven from natural sources and that all the other metals were anthropogenically driven from industrial activities (As, Ba, Cd, Cr, Cu, Se, and Sn) and traffic emissions (Pb, Ni and V). Results of the applied risk assessment indicated that the higher risk of occurrence of adverse non-carcinogenic health effects is associated with the exposure of children to Al, Fe, As, Cr, Pb and Zn via the ingestion pathway and that carcinogenic health effects are not expected to occur from the exposure to metals in the road dust of the Delta region. However, given the large uncertainties associated with the estimates of toxicity values and exposure factors, and the absence of site-specific biometric factors, these results should be regarded as a screening data. Further research should be undertaken before any definite conclusions regarding potential health effects are drawn.

Surface and core sediments from Lake Maryut, Egypt, one of the most polluted lakes in Egypt, were analyzed for polycyclic aromatic hydro- carbons (PAHs) using gas chromatography-mass spectrometry. This investigation represents the first extensive study of the distribution and sources of PAHs in sediments from Lake Maryut. The total PAHs concentrations (sum of 39 PAH compounds) in surface sediments varied greatly depending on the sampling location and ranged from 106 to 57,800 ng/g dry weight with a mean concentration of 6,950 ng/g. The most polluted areas are distributed in areas which are mainly influenced by municipal sewage and industrial effluent discharges, suggesting a direct influence of these sources on the pollutant distribution patterns. PAH concentrations were one to two orders of magnitude higher in comparison with those reported for riverine/ estuaries systems around the world. Molecular indices, such as pyrogenic index (PI), methylphenanthrenes to phenanthrene ratio, HMWPAH/LMWPAH, A-PAHs/P- PAHs, FL/FL+PY, BaP/BaP+C, IP/IP+BgP, and Per/ ∑(penta-aromatics) were calculated to evaluate differ- ent hydrocarbon origins and their relative importance. In general, sediments from the main basin and northwest basin of Lake Maryut showed the highest PAH concentrations with petrogenic signatures, indi- cating major sources of petrogenic PAHs in the city. On the other hand, lower levels of PAHs with a pyrogenic signature were widely recorded in areas that are distant from anthropogenic sources. At other locations, both petrogenic and pyrogenic inputs were significant. The concentrations of perylene relative to the penta-aromatic isomers are dominant especially in locations associated with terrestrial inputs and in the deepest core sediments, indicating diagenetic origin for the presence of perylene. Temporal trends of PAH concentrations in both cores sediments were influenced by input pathways and followed the economic development and the environmental policies of the Egyptian Government in the last 15 years. Finally, PAH levels in sediments were compared with Sediments Quality Guidelines (effects range median-effects range low) for evaluation probable toxic effects on organism. Results suggest an ecotoxicological risk for benthic organisms mainly in the main basin area, where high concentrations of PAHs were found in sediments influenced by anthropogenic activities.

To assess the status of polycyclic aromatic hydrocarbon (PAH) contamination in sediments of Hadhramout coastal area, Gulf of Aden, Yemen, 17 surface sediment samples were collected in March–April 2005 and analyzed for PAHs with 2–6 benzene rings by gas chromatography–mass spectrometry (GC-MS). The concentrations of PAHs in surface sediments were in the range of 2.2–604 ng g − 1 (average value: 82.4 ng g − 1 ). PAHs contamination is highest in proximity to harbour activities, near Al-Dhabah petroleum terminal and urban areas. Comparison of the concentration range with a worldwide survey of sedimentary PAH concentrations ranked PAH contamination in Hadhramout coastal sediments as low to moderate. Assessment of PAH sources in Hadhramout coastal sediments suggested that they originated largely from petrogenic sources. PAHs of pyrolytic origin were found in sediments from urbanized areas. Adverse effects on benthic communities are not expected at the levels of PAHs contamination observed from harbour and industrial areas.

The distribution of trace metals between crude petroleum and its heavy products has been studied by emission spectrography. The highest concentration of V, Ni, Sb and Mg was associated with the asphaltic fraction. A correlation has been established between the V/Ni, V/Sb and Ni/Sb indices and the geologic age of petroleum. Examination of gas and diesel oils for suitability as catalytic cracking feedstocks has been made on the basis of their Ni equivalent. Lubricating oil was found to retain little or no trace metals from the parent crude oil. The relatively high V content of fuel oil can affect refinery equipment, distillation units and linings of industrial furnaces. Other trace metals are non-destructive or only slightly destructive.

Molecular geochemical properties of crude oils and surface petroleum seeps from the southern part of the Gulf of Suez were evaluated. The characterizations of individual aliphatic, aromatic, and biomarker compounds were based on gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) analyses. The results provided strong evidence for a close genetic association of these samples. The geochemical characteristics suggest an origin from Tertiary source rocks deposited in a normal marine environment that received continental runoff. The molecular signatures of the investigated samples were very similar to those of the Lower Miocene Rudeis Formation source rock in the southern Gulf of Suez. Further, biomarker fingerprints of the investigated oil seeps were compared with those of the Dead Sea asphalt, as well as the bitumen from some Egyptian mummies reported in the literature. The results demonstrate that oil seeps from the southern end of Gebel El Zeit were used by ancient Egyptians for embalming. © 2005 Wiley Periodicals, Inc.

Little data are available on the levels of polycyclic aromatic hydrocarbons (PAHs) in the sediments of the Mediterranean Sea Coast of Egypt in general and the Alexandria coastal zone in particular. It was therefore deemed necessary to set up a monitoring programme to determine the current concentrations of PAHs in bottom sediments, and to identify any area where high concentrations of these potential hazardous contaminants were present in the Western Harbour of Alexandria. The composition, distribution and the source of PAHs in surficial sediments of the harbour were investigated. To document the spatial PAH input, surficial sediment samples from 23 locations throughout the harbour were analysed. as]Results and Discussion The total PAH load determined in the surficial sediment samples ranged from 8 to 131150 ng g1 dry wt, generally with most of the samples having total concentrations of PAHs greater than 5000 ng g1 dry weight. The highest concentration of total PAHs was recorded in sediments of the inner harbour. Ratio values of specific compounds such as phenanthrene to anthracene, fluoranthrene to pyrene, methyl-phen-anthrene to phenanthrene, methyl-dibenzothiophenes to dibenzothiophenes, alkylated to non-alkylated and high molecular weight to low molecular weight PAH, were calculated to evaluate the possible source of PAH contamination in the harbour sediments. Two main sources of PAH in the study area have been found: pyrolytic and petrogenic. Interferences of rather petrogenic and pyrolytic PAH contaminations were noticed for most samples. The dominant sources of PAH appear to be the combustion processes through run-off, industrial and sewage discharges, and atmospheric input. The concentrations of PAHs were generally above levels expected to cause adverse biological effects. Information from this study and any other relevant studies should be useful in designing future strategies for environmental protection and management of the harbour.

In an attempt to examine the suitability of chemical fingerprinting methods in oil spill investigations, multiple parameters sensitive to both sources and degree of weathering were used to characterize spilled oil samples and to distinguish spilled hydrocarbons from sources unrelated to the spill in shoreline of the Gulf of Suez, Egypt. The characterizations of individual aliphatic and aromatic compounds were based on gas chromatography and gas chromatography/mass spectrometry analyses. The distribution of n-alkanes, polynuclear aromatic hydrocarbons (PAHs) and alkyl PAHs in the source oil and an oil slick collected 72 h after the spill were very similar. Major compositional changes observed in a weathered oiled sediment collected nine months after the spill from the shoreline at the spill location were consistent with previous studies. Molecular parameters of hopane and sterane biomarkers were very similar in the source oil, the spilled oil and the highly weathered oiled sediment. The similarity in biomarker compositions provided a strong evidence for a close genetic association of these samples. Ratios of C2-chrysenes/C2-phenanthrenes and C2-chrysenes/C2-dibenzothiophenes, the pregnane index (sum of the concentrations of C21 and C22 steranes over total concentration of steranes×100), and the tricyclic terpane index (sum of the concentrations of C19 and C30 tricyclic terpanes over total concentration of terpanes×100) clearly differentiated the refined oil products from crude oils. The composition of bilge oil indicated enrichment of late eluting steranes and terpanes and showed biomarker distributions similar to natural petroleum. The results further support that sterane and terpane biomarker analyses could differentiate oil samples of different sources even though they were sometimes indistinguishable in PAH and alkane compositions.

Seven crude oils representing the different petroleum-bearing basins in the Western Desert were characterized by a variety of biomarker and nonbiomarker parameters. For comparison, one crude oil from the Gulf of Suez region has also been studied. The oils have been analyzed for geochemical biomarkers using GC and GC-MS techniques. The results reveal significant differences within the oils that suggest five oil types. Type 1 oils from the Gulf of Suez show C 29 /C 30 17α(H) hopane ratio >1, high C 35 homohopane index, and the presence of considerable amounts of gammacerane indicating a marine saline carbonate or evaporite source rock and highly reducing (low Eh) conditions. Type 2 oils from Matruh basin and type 3 oils from Shushan basin are very similar and show relatively high Pr/Ph ratios, low sulfur and metal contents, paucity of C 30 steranes and the presence of high relative abundance of 17α(H) diahopane (C 30 *) suggesting that they probably originated from source rocks containing a significant proportion of higher plant material. Another related feature of these oils is the absence of 18α(H)-oleanane which suggests a source age older than Cretaceous. Type 4 oils from Abu-Elgharadig basin show terpane distribution dominated by C 24 tricyclic, absence of C 30 *-diahopane and medium diasterane/sterane ratios which reflect generation from marine siliciclastic source rocks. Type 5 oils from Alamein basin possess source biomarkers indicating a mixed contribution of terrestrial and marine sources. The presence of measurable amounts of oleanane in this type of oils suggests source rocks deposited in deltaic or near shore environment in Post-Cretaceous basin.

Maturity-dependent trends of a number of biomarker and nonbiomarker geochemical parameters were examined in crude oils from the Western Desert and the Gulf of Suez, Egypt. Molecular maturity assessments showed that all oils are at an advanced level of thermal maturity, and many ratios, such as CPI, hopane/hopane + moretane, C31 22S/22S + 22R hopanes and C29 ααα-20S/20S + 20R steranes were almost identical and have reached their thermal equilibrium values. Changes in the Ts/Tm and C29 ββ/(ββ + αα) steranes however, showed a more advanced level of thermal maturity for Umbaraka oil. On the other hand, correlations utilizing the nonbiomarkers API gravity, ΣV, Ni, sulfur content, sat/arom, and Ph/n-C18 ratios did show more distinct differences and are consistent between the oils.

To evaluate the chemical fingerprint of hydrocarbons in airborneorganic matter in the arid environment of Alexandria City, Egypt,the compositions of aliphatic and aromatic compounds were determined in suspended particulate material collected from a street undergoing heavy traffic in central Alexandria and in bulkdeposition samples collected from a site representing an area increasingly influenced by human and industrial activities. Qualitative and quantitative characterizations of individual compounds were based on gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) analyses. More than 100 organic compounds are quantified in each sample, including n-alkanes, isoprenoids, polycyclic aromatic hydrocarbons(PAHs), sulfur-bearing heterocyclics, steranes/diasteranes, terpanes and aromatic steroids. The use of hydrocarbon profilesand ratios for identifying sources and processes is discussed.The molecular distribution of alkanes revealed that the mainsource of these compounds is from petroleum contamination withtrace input of vascular plant wax. The PAH profiles, especiallythe relative abundance of alkyl-PAHs and sulfur-containing heterocyclics, showed that PAHs are chiefly derived from trafficsources. The results further indicated that diesel vehicles aremore important PAH sources than gasoline vehicles. In addition,the source fingerprint of fossil fuel biomarkers such as steranes, terpanes and aromatic steroids agreed well with thefingerprint of unburned lubricating oil, which are probably contributed to vehicle exhaust emissions.

Tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) compounds were quantitatively determined in surface-sediment samples collected from 23 sites in the commercial harbor of Alexandria City, Egypt. Butyltin concentrations in sediments varied widely depending on the sample location, ranging from less than 0.1 to 186 ng g−1 of Sn for MBT, less than 0.1 to 379 ng g−1 of Sn for DBT, and 1 to 2,067 ng g−1 of Sn for TBT. Elevated TBT concentrations, ranging from 727 to 2,067 ng g−1 of Sn were observed in harbors, marinas, and near ship-repair facilities, indicating that the butyltin-containing, antifouling paints of boats and vessels are the major source of butyltin contamination. The TBT concentration decreased rapidly away from potential source areas of boat docking and repair facilities. The high relative concentrations of TBT in the sediments indicated that degradation processes in the sediments are minor, probably due to the anoxic sedimentary conditions at the sampling sites and/or relatively fresh input of TBT to these sites.

The acid fraction of crude oils and related source rocks of different stratigraphic units from the Gulf of Suez and Western Desert, Egypt were analyzed by GC and GC/MS. Normal alkanoic acids (n-C9−n-C30) were the dominant series (with the predominance of even-carbon numbers maximizing at n-C16, n-C18 or n-C22while iso- and anteiso- branched acids were minor constituents. All samples showed a preference of short chain acids (n-C10−n-C19 with respect to long chain acids (n-C20+) typical of marine oils and source rocks. The n-alkanoic acids distribution suggests a predominant algal and/or bacterial contribution. The presence of high relative abundance of mono and di-unsaturated carboxylic acids in a number of samples point to recent microbial activity. Distributions of n-alkanoic acids in the range (C12−C22) show striking similarities with the n-alkane distributions, indicating that both series may, at least in part, be diagenetically related by decarboxylation of the acids. Dehydroabietic acid has ...

In an attempt to investigate the suitability of a multibiological marker approach for defining the origin of petroleum pollution in marine systems, the aliphatic hydrocarbon compositions of tar ball samples collected from the beaches of a small island impacted by heavy tar loads were determined by gas chromatography and gas chromatography/mass spectrometry. The tar ball samples, as collected, were at low stages of biodegradation and had diverse physical appearance. The majority of the samples (as many as 7 of the 10) appeared to be heavy fuel oils—possibly Bunker C. The GC traces for the other three tar balls, however, indicated that they were crude oils probably from tanker ballast washings or other non-point sources like the oil entering from the adjacent North Mediterranean. The biomarkers of the sterane and hopane series in these samples, however, had remained unaffected by weathering, and their distributions revealed significant differences among the samples suggesting multiple sources of the tar balls. The tar ball samples could be genetically subdivided into four groups on the basis of their biomarker fingerprints. A marine carbonate or evaporite, hypersaline, anoxic depositional environment of the petroleum source rock for Type I residues could be inferred from the even-carbon-number predominance of n-alkanes, the high relative abundance of gammacerane and the predominance of C35 relative to C34 17α(H)-homohopanes. Higher plant contribution and a deltaic environment of source rock deposition could be concluded for Type II residues from the high concentrations of oleanane and diasteranes. On the other hand, Type III residues possessed geochemical characteristics consistent with a normal marine carbonate or evaporite source depositional environment under normal saline, reducing conditions. Finally, type IV residues had biomarker signatures intermediate between Types II and III.

Crude oils from the Gulf of Suez and the North Western Desert of Egypt have been analyzed for geochemical biomarkers using GC and GC-MS techniques. The biomarker compositions of the crude oils have been used to differentiate crude oils of non-marine, normal marine and marine carbonate sources. The geochemical features of Zaafarana crude oil from the Gulf of Suez Basin indicate a marine carbonate depositional setting. One crude oil from Budran however, possesses geochemical characteristics consistent with an origin from source rock deposited in normal marine conditions. Bahar and Morgan show normal marine source rock deposition environment with terrigenous organic matter input. On the other hand, the crude oils from the North Western Desert have bulk and biomarker characteristics cosistent with non-marine depositional setting, with the exception of one oil sample which appears to have a mixed marine/terrestrial sources. The presence of oleanane in some of these oils suggests source rocks deposited...

The distribution patterns of methylhomologs of naphthalene and phenanthrene in five crude oils from the southern part of the Gulf of Suez, Egypt, have been examined by quantitative capillary gas chromatography (GC) and computerized gas chromatography/mass spectrometry (GC/MS). In general, the relative abundance of individual naphthalenes and phenanthrenes were not significantly different in the five oil samples. Correlation between the source rock deposition and the abundance of specific methylnaphthalene and melhylphenanthrene isomers are consistent with a marine type source materials for the analyzed Gulf of Suez oils. Maturity parameters based on methylnaphthalene and methylphenanthrene isomers were almost identical and are consistent with an advanced stage of maturity. Further, calculated vitrinite reflectance (Re) confirmed that the sediments have a range of maturity within the “oil window”.

Five crude oils from some producing wells in the southern part of the Gulf of Suez were characterized using a variety of organic geochemical parameters. The results reveal significant differences within the oils from the Gulf of Suez basin that suggest two oil types and one mixed type. Type 1 oils from Ras Fanar and East-Zeit fields show a high relative abundance of gammacerane indicating a marine saline-source depositional environment. Another related feature of these oils is the predominance of C 35 over C 34 17α( H )-homohopanes. Type 2 oils from Gama and Amal-9 wells show oleanane indices over 20%, indicating that they originated from an angiosperm-rich, Tertiary source rock. Type 3 oil from Amal-10 well has geochemical characteristics intermediate between those of types 1 and 2. This may reflect mixing of oils from the sources of both types 1 and 2. The geochemical characteristics of the oils vary sufficiently to suggest multiple sources. The type 1 oils possess geochemical characteristics consistent with Upper Cretaceous Brown Limestone or Lower Eocene Thebes Formation carbonate source rocks. Type 2 oils are very similar in geochemical character to the Lower Miocene Rudeis Formation source rocks.

Conventional organic geochemical and biomarker parameters are used together to provide information on source organic matter input, depositional environment, and the correlation between crude oils from different pay zones and geographical locations in Egypt. The method of biomarker characterization is based on the fractionation of crude oils by liquid chromatography into three main compound classes: saturated hydrocarbons, aromatics and N, S, O components. The identities of specific compounds and the carbon number distribution of n -alkanes and acyclic isoprenoids were determined by capillary column gas chromatography. On the basis of correlation plots between biomarker and nonbiomarker parameters, the oil samples are classified into three main groups. The first group includes oil samples from the central part of the Gulf of Suez (Balayem Land, Bakr, Gharib and July fields) and is typical of crude oils generated in a strongly reducing environment. The second group comprises oils generated from sediments deposited in suboxic conditions and includes oils from the south central and southern part of the Gulf (Ras Fanar, Shark El-Zeit, Amal 9, Amal 10 and Gamma) and Yidma crude from the Western Desert. The third group includes oil samples of the Western Desert from the Umbaraka, Khalda and Meleiha fields, which are typical of oils accumulated under oxic palaeoenvironmental conditions.

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were determined in sediment samples collected from 34 locations in Lake Qarun, Egypt to elucidate their concentrations, distribution, possible sources and potential ecological risk. A total of 25 OCPs and 29 PCBs were identified and quantified. OCPs and PCBs were found to be ubiquitous pollutants in the aquatic environment of Lake Qarun, particular near urban areas reflecting the local usage and input of these pollutants. Total concentrations of OCPs and PCBs in sediments ranged from 1.01 to 164.8 ng g −1 and 1.48 to 137.2 ng g −1 , respectively. Among OCPs, γ-HCH, heptachlor, aldrin, endrin, p,p′-DDE, oxy-chlordane and endosulfan I and II were the most abundant compounds. The composition of PCB congeners was dominated by the tri-, tetra-, penta- and hexa-chlorinated biphenyls. The ratios of certain metabolites (isomers) to their parent compounds (mixtures) indicated there are still new inputs of lindane, endrin, heptachlor and technical endosulfan to Qarun Lake, while the ratios of (p,p′-DDE + p,p′-DDD)/∑p,p′-DDTs indicate earlier usage of DDT. Contamination levels of PCBs and HCHs can be categorized as moderate to high compared to other urbanized regions worldwide. According to established sediment quality guidelines, γ-HCH, endrin and chlordanes would be more concerned OCP species for the ecotoxicological risk in Lake Qarun.

A number of structural isomers of C 33 2,5-dialkylthiophenes (I), C 33 , C 37 , C 38 2,6-dialkylthianes (II), and 2,5-dialkylthiolanes (III) have been identified in sediment extracts from the Nordlinger Ries, southern Germany. The identifications are based on gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) analysis and confirmed by carbon skeleton determination on desulfurization products using Raney nickel treatment. All the organic sulfur compound classes mentioned exhibit structural distributions dominated by a limited number of all theoretically possible isomers. This provides further evidence for the formation of these compounds by abiogenic incorporation of sulfur into functionalized lipids at the early stages of diagenesis

Unusually high concentrations of C16 and C18 10-oxo-carboxylic acids were identified in the free acid fractions of bitumens from sulphur-rich black shales from the Nordlinger Ries (southern Germany). After isolation, the structure of the C18 homologue was elucidated by mass spectral interpretation, derivatization (formation of diol and conversion into diacetate), IR and 13C NMR spectroscopy and comparison of spectral data with those of closely related standards. These acids are assumed to be derived from oxidation of Δ9 fatty acids, which are common constituents of microorganisms, possibly in the course of microbial sulphate reduction which was a major redox process during early diagenesis in these sediments.

Series of C-ring monoaromatic steroid hydrocarbons (C21, C22, C27 C29) and triaromatic steroid hydrocarbons (C20, C21, C26 C28) have been recognized in the aromatic hydrocarbon fraction of Alamein crude oil from the western desert, Egypt. Detection of these compounds were based on mass fragmentography of the key ions m/z 253 and m/z 231 and comparison of the mass spectra and relative retention times with literature data. The predominance of the C29 monoaromatic steroids and C28 triaromatic steroids provide further evidence for a land plant origin of Alamein oil. The results substantiate previous evidence of the occurrence of an aromatization process with increasing maturation and indicate a moderate maturity level for Alamein oil.

Three main series of bound steroidal acids have been tentatively identified, in low concentrations, in the hydrolysates of kerogens and the extractable polar fractions of sediments from the Nordlinger Ries (southern Germany), and in a kerogen sample from the Monterey Formation (California). The results provide further evidence of the widespread occurrence of 3-carboxysteroids and indicate that they are chemically bonded to the complex network of kerogen through ester linkages. This suggests that these compounds could represent a yet unrecognized family of compounds occurring in the biosphere

Free fatty and hopanoic acids, and hydrocarbons of five organic- and sulfur-rich lacustrine sediments from Nordlinger Ries black shales (southern Germany), have been studied by gas chomatography and computerized GC-MS. The results indicate that Nordlinger Ries sediments contain abnormally high concentrations of those free acids (up to 57% of total extractable bitumen). Besides n-alkanoic, monomethyl, and isoprenoid acids common to any other immature sediments, high concentrations of C 16 and C 18 10-oxoalkanoic acids are unusual constituents of these sediments. The high concentrations of fatty acids in the bitumens are attributed to early diagenesis. The carbon distributions of the acids are consistent with an origin mainly from planktonic and microbial organisms

In order to obtain more information on the structural entities bonded to the macromolecular structure of Monterey kerogen, the solvent-extractable acidic products obtained by mild alkaline hydrolysis were investigated by gas chromatography and combined gas chromatography-mass spectrometry analysis. On the basis of the results obtained, the previously proposed structural feature of Monterey kerogen is expanded to include saturated normal monocarboxylic acids (C 8 -C 36 ), saturated normal α,ω-dicarboxylic acids (C 7 -C 29 ), isoprenoid acids (C 14 -C 17 , C 19 -C 21 ), iso and anteiso acids (C 11 -C 18 ), unsaturated acids (C 16:1 , C 18:1 ), aromatic acids, hopanoid acids, and 3-carboxycholestane, as well as a complex mixture of alkylated thiophene carboxylic acids (C 6 -C 11 )

Alkaline hydrolysis of kerogen from a Miocene lacustrine sediment (Nordlinger Ries, southern Germany) afforded a series of cembrenoid diterpenes characterized by a 14-membered ring system together with a second, probably related, series of yet unidentified structure. This is the first report of the occurrence of these compounds in fossil organic matter. The interpretation of cembrenoids as molecular markers of arid or semiarid climate is consistent with other information about the depositional environment of the former Nordlinger Ries crater lake.

In an attempt to obtain a greater insight into the structure of Monterey kerogen, partially oxidized kerogen concentrates obtained from Na2Cr2O7glacial CH3COOH stepwise oxidation were examined by Fourier transform infrared (FT-i.r.) analysis. The results show that the kerogen samples contain condensed aromatic systems to which are attached OH and Oalkyl functional groups, and also indicate that the majority of N and S atoms are within the ring structure. It was found that the carbonyl, aromatic and ether groups are not affected while CH2 groups are lost upon oxidation. Furthermore, it was concluded that in kerogen oxidation, organic sulphur can be fixed as inorganic sulphate in the presence of COO− in a manner similar to coal oxidation.

Pentacyclic triterpenoids released from Green River kerogen by a low temperature, mild, stepwise oxidative degradation using sodium dichromate in glacial acetic acid have been investigated by high resolution gas chromatography and computerized gas chromatography-mass spectrometry. Three series of stereoisomeric hopanoic acids (C 30 –C 33 ) were found based on their αβ, ββ, and βα configurations. In addition, the following compounds were tentatively identified: 29,30-bisnorhopanoic acid, 30-norhop-22-one, 22,29,30-trinorhopan-21-one, 3-hopanone, and 3-gammacerone. The distribution of isomeric hopanoic acids supports previous suggestions of an extremely mild thermal history of Green River kerogen. Bonding of these triterpenoids to kerogen is likely to occur through the terminal positions (e.g. positions 3, 21, 22, 30, 31, etc.). The results also provide further evidence in favor of the microbiological origin of at least part of the organic matter in Green River oil shale kerogen.

The main objective of this study was to investigate compositional changes in a range of source- and weathering-dependent molecular parameters in oil residues in the arid terrestrial environment of Al-Alamein, Egypt. The results of aromatic hydrocarbon analysis demonstrated the stability of several aromatic hydrocarbon ratios in oil residues over a wide range of weathering and hydrocarbon concentrations. The ratios of C2-dibenzothiophenes/C2-phenanthrenes (C2-DBTs/C2-PHENs), C3-dibenzothiophenes/C3-phenanthrenes (C3-DBTs/C3-PHENs), C2-chrysenes/C1-chrysenes (C2-CHRYs/C1-CHRYs), and C2-dibenzothiophenes/C1-dibenzothiophenes (C2-DBTs/C1-DBTs) were nearly constant in oil residues of varying degrees of weathering. Biomarker ratios of hopanes and steranes were useful for source identification even for severely weathered oil residues. The data confirmed previous observations that C29 20S/(20S+20R) and C29 ββ/(ββ+αα) sterane epimer ratios, and C29/C30, C30 αβ/(αβ+βα), C31 22S/(22S+22R) hopane ratios correlate well even after extensive weathering of spilled oils, although some exceptions were encountered for an extensively weathered surface sample. The data provided clear evidence of correlation between samples of the weathered oil residues and the possible source oil. Moreover, the results of biomarker compositions were in good agreement with weathering classification based on alkanes and aromatic hydrocarbons. In general, samples with lowest pregnane indices (PI) and tricyclic terpane indices (TriTI) showed the lowest concentrations of n-alkanes and alkylated polycyclic aromatic hydrocarbon (PAH) homologues, the highest weathering ratios (WRs), the highest values of unresolved complex mixture (UCM)/total resolved peak (TRP) ratios, and the highest ratios of C2 and C3-alkylated CHRYs to their counterparts in the PHEN and DBT series. Keywords: Oil residues, Weathering, Terrestrial environment, Chemical fingerprinting, Alkanes, Polycyclic aromatic hydrocarbons

Green River shale kerogen was degraded by a careful five-step oxidation with sodium dichromate in glacial acetic acid. Products isolated from each oxidation step were examined by capillary gas chromatography and combined gas chromatography-mass spectrometry. The analyses revealed the presence of several homologous series. Saturated normal monocarboxylic acids (C 6 C 35 ) and saturated normal α,ω-dicarboxylic acids (C 4 C 33 ) were the major constituent series, while isoprenoid acids (C 14 C 21 , except C 18 ), iso and anteiso acids (C 6 C 16 ), branched dicarboxylic acids (C 20 C 29 ), triterpenoidal acids (C 27 C 33 ), cyclic, and oxo-acids were the minor constituent series. Moreover, a few aromatic acids, branched ketones, heterocyclic compounds, as well as a series of (C 25 C 30 ) n -alkanes were identified. The results were discussed in terms of the qualitative and quantitative variations of the products with duration of oxidation. The data corroborate the conclusion of a predominantly open chain crosslinked aliphatic structure for Green River kerogen, and indicate that aromatic structures are mainly in the form of isolated phenyl and tolyl groups. The results further confirm the presence of etioporphyrin as a significant constituent in the kerogen studied.

Computerized capillary gas chromatography-mass spectrometry (GC-MS) was employed to investigate maleimides (1H-pyrrole-2,5-diones) produced from a controlled stepwise oxidation of bitumen-free kerogen samples isolated from Green River and Monterey oil shales. On the basis of the evidence obtained from the analysis of all fractions, it is suggested that etioporphyrin species are most likely entrapped in the molecular sieve type network of kerogen

On realise l'oxydation menagee par etapes, des kerogenes de schistes de Green River et de Monterey dans le but d'etudier la distribution en dimension des structures aliphatiques en chaine droite et le degre de reticulation des deux kerogenes