High Molecular Hydrocarbons Research Articles

Surfactant-enhanced biodegradation of high molecular weight polycyclic aromatic hydrocarbons by stenotrophomonas maltophilia

The objectives of this study were to isolate and evaluate microorganisms with the ability to degrade high molecular weight polycyclic aromatic hydrocarbons (PAHs) in the presence of synthetic surfactants. Stenotrophomonas maltophilia VUN 10,010, isolated from PAH-contaminated soil, utilized pyrene as a sole carbon and energy source and also degraded other high molecular weight PAHs containing up to seven benzene rings. Various synthetic surfactants were tested for their ability to improve the PAH degradation rate of strain VUN 10,010. Anionic and cationic surfactants were highly toxic to this strain, and the Tween series was used as a growth substrate. Five nonionic surfactants (Brij 35, Igepal CA-630, Triton X-100, Tergitol NP-10, and Tyloxapol) were not utilized by, and were less toxic to, strain VUN 10,010. MSR and log Km values were determined for fluoranthene, pyrene, and benzo[a]pyrene in the presence of these nonionic surfactants and their apparent solubility was increased by a minimum of 250-fold in the presence of 10 g L-1 of all surfactants. The rate of pyrene degradation by strain VUN 10,010 was enhanced by the addition of four of the nonionic surfactants (5-10 g L-1); however, 5 g L-1 Igepal CA-630 inhibited pyrene degradation and microbial growth. The specific growth rate of VUN 10,010 on pyrene was increased by 67% in the presence of 10 g L-1 Brij 35 or Tergitol NP-10. The addition of Brij 35 and Tergitol NP-10 to media containing a single high molecular weight PAH (four and five benzene rings) as the sole carbon source increased the maximum specific PAH degradation rate and decreased the lag period normally seen for PAH degradation. The addition of Tergitol NP-10 to VUN 10,010 cultures which contained a PAH mixture (three to seven benzene rings) substantially improved the overall degradation rate of each PAH and increased the specific growth rate of VUN 10,010 by 30%. Evaluation of the use of VUN 10,010 for degrading high molecular weight PAHs in leachates from surfactant-flushed, weathered, PAH-contaminated sites is warranted. Copyright 1998 John Wiley & Sons, Inc.

A detailed analysis of the pyrolysis products from dioctyltin maleate and its mixture with PVC

The thermal decomposition of dioctyltin maleate (DOTM) and a blend of PVC and DOTM has been studied in air, nitrogen and under vacuum. TG was used to examine the effect of different amounts of DOTM on stability. The PVC/DOTM mixture shows delayed dehydrochlorination in both the air and inert environment compared with PVC. The blend shows more thermal stability in an inert atmosphere than in air. The decomposition products from a blend containing a high loading of DOTM were investigated using Thermal Volatilisation Analysis (TVA) and Subambient Thermal Volatilisation Analysis (SATVA). Gas, liquid and tar fractions were separated and analysed by IR spectroscopy, on-line mass spectrometry or GC-MS. High molecular weight polycyclic aromatic hydro-carbons (PAH) found in the pyrolysis of pure PVC were not found from the blend. The pyrolysis in the presence of air rather than inert atmosphere does not change the nature of the products, although the relative amounts may be different. Traces of oxygen-containing volatile products are formed from the blend, while most of the oxygen-containing groups formed in the polymer pass into the tar as large fragments split from the crosslinked network. Dioctytin dichloride is the most important product apart from HCl from the pyrolysis of the PVC DOTM mixture.

PAH growth and soot formation in the pyrolysis of acetylene and benzene at high temperatures and pressures: Modeling and experiment

The growth of high molecular polycyclic aromatic hydrocarbons (PAHs) before soot inception is modeled during C 2 H 2 and C 6 H 6 pyrolysis at temperatures between 1600 and 2400 K, p =60 bar, and C-atom concentrations of (3.8–4.0)×10 −6 mol/cm 3 . The formation of high molecular PAH is mainly computed by two different reaction pathways: (1) successive H-abstraction C 2 H 2 additions and (2) a combinative ring-ring condensation of aromatics. The calculations are compared with measurements obtained from C 2 H 2 and C 6 H 6 pyrolysis by the shock wave method. From reaction flux analysis, it is deduced that the combinative route plays a major role in forming PAHs, especially at early reaction times. The calculated induction times of higher PAHs reasonably reflect the experimental trends of soot inception. The slope of the computed and measured induction times in dependence on the temperature resulted in a similar activation energy for high molecular PAH and soot formation. It is concluded that soot mass growth rates during the pyrolysis of C 2 H 2 and C 6 H 6 are strongly related to PAH formation. Thus, the decrease of the soot mass growth rates during C 2 H 2 pyrolysis for T >2000 K seems to be substantially influenced by a change in the nucleation process of soot precursors.

Sediment contaminants and biological effects in southern California: Use of a multivariate statistical approach to assess biological impact

AbstractThis study attempts to predict biological toxicity and benthic community impact in sediments collected from two southern California sites. Contaminant concentrations and grain size were evaluated as predictors using a two‐step multivariate approach. The first step used principal component analysis (PCA) to describe contamination type and magnitude present at each site. Four dominant PC vectors, explaining 88% of the total variance, each corresponded to a unique physical and/or chemical signature. The four PC vectors, in decreasing order of importance, were: (1) high molecular weight polynuclear aromatic hydrocarbons (PAH), most likely from combusted or weathered petroleum; (2) low molecular weight alkylated PAH, primarily from weathered fuel product; (3) low molecular weight nonalkylated PAH, indicating a fresh petroleum‐related origin; and (4) fine‐grained sediments and metals. The second step used stepwise regression analysis to predict individual biological effects (dependent) variables using the four PC vectors as independent variables. Results showed that sediment grain size alone was the best predictor of amphipod mortality. Contaminant vectors showed discrete depositional areas independent of grain size. Neither contaminant concentrations nor PCA vectors were good predictors of biological effects, most likely due to the low concentrations in sediments.

Multi-Dimensional Liquid Chromatography Coupled with Atmospheric Pressure Chemical Ionization LC-MS for Profiling High Molecular Mass Polycyclic Aromatic Hydrocarbons

Abstract High molecular mass polycyclic aromatic hydrocarbon (PAH) fractions were isolated from organic solvent extracts of a variety of matrices including bottom sediments, suspended sediments, coal tar-contaminated sediments and freshwater mussels from Hamilton Harbour (western Lake Ontario). Isomeric molecular mass PAH fractions were prepared using a normal phase HPLC method. The high molecular mass PAH fractions were analyzed by atmospheric pressure chemical ionization (APCI) LC-MS, and the resulting chromatographic profiles were compared. The effects of different HPLC mobile phases on mass spectrometer instrument performance are also briefly described.

High molecular weight polycyclic aromatic hydrocarbons in hydrothermal petroleums from the Gulf of California and Northeast Pacific Ocean

Hydrothermal petroleums and heavy tars have been analyzed for polycyclic aromatic hydrocarbons (PAH) with molecular weights greater than that of coronene (300 da). Samples from the hydrothermal systems in the Guaymas Basin (Gulf of California) and in the Escanaba Trough and Middle Valley (Northeastern Pacific) were analyzed by gas chromatography-mass spectrometry and high pressure liquid chromatography with diode-array absorbance detection. Mass spectra and fluorescence spectra were used to characterize the compounds. Several large PAHs with six and more rings were identified among the heavy PAH. Production routes via one-ring build-up and Scholl-condensation are proposed to explain the observed structures. The variations in PAH concentrations and distributions between samples from different locales are a consequence of the hydrothermal conditions of generation, migration, and post-depositional alteration.

Evidence of prooxidative biological action of ethanol

The removal and transformation of seven high molecular weight polycyclic aromatic hydrocarbons (PAHs), namely benz[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, indeno[1,2,3-c,d]pyrene and benzo[g,h,i]perylene, by a freshwater microalga Selenastrum capricornutum under gold and white light irradiation was studied. The two light sources did not result in significant differences in the biodegradation of the selected PAHs in live algal cells, but white light was more effective in promoting photodegradation than was gold light in dead cells. The removal efficiency of seven PAHs, as well as the difference between live and dead microalgal cells, was PAH compound-dependent. Benz[a]anthracene and benzo[a]pyrene were highly transformed in live and dead algal cells, and dead cells displayed greater transformation levels than live cells. Further investigation comparing the transformation of single PAH compound, benzo[a]pyrene, by S. capricornutum and another green microalgal species, Chlorella sp., demonstrated that the transformation in dead cells was similar, indicating the process was algal-species independent. Dead algal cells most likely acted as a photosensitizer and accelerated the photodegradation of PAHs.

Pilot-Scale Demonstration of DARAMEND Enhanced Bioremediation of Sediment Contaminated with Polycyclic Aromatic Hydrocarbons in Hamilton Harbour

Abstract In 1992, GRACE Dearborn, Inc. was contracted by Environment Canada to conduct a field-scale demonstration of the DARAMEND bioremediation technology under the auspices of the Great Lakes Cleanup Fund's Contaminated Sediment Treatment Technology Program. The demonstration on approximately 150 tonnes of sediment dredged from Hamilton Harbour was completed by January 1994. Two distinct batches of sediment were treated. One batch of 90 tonnes of sediment, dredged directly from the harbour without any pretreatment, is the focus of this paper. Sediment was received in October 1992 and was treated through to December 1993. Treatment was conducted in an high-density polyethylene-lined treatment cell that was covered by a steel framed greenhouse. The treatment involved amending, tilling and closely controlling the sediment water content. In approximately 300 days of treatment, the level of total polycyclic aromatic hydrocarbon contamination was reduced from approximately 1,000 µg/g to 100 µg/g, corresponding to a destruction and removal efficiency of approximately 90%. Notably, the high molecular weight polycyclic aromatic hydrocarbons (containing 4 to 6 benzene rings) were effectively degraded to concentrations below the Ministry of the Environment and Energy’s Soil Placement Guideline for controlled fill (MOEE 1992). The trend in the data suggest that following addition of DARAMEND amendment and several months of active management, the polycyclic aromatic hydrocarbons would continue to biodegrade as a result of the DARAMEND amendment even without active management of the sediment.

Uptake and elimination of benzo[a]pyrene in the terrestrial isopod Porcellio scaber.

In isopods from contaminated sites relatively low levels of high molecular weight polycyclic aromatic hydrocarbons (PAHs) have been observed, which may be caused by either a low bioavailability or a high elimination rate. To shed light on this, the uptake and elimination rates of benzo[a]pyrene were estimated for the isopod Porcellio scaber. The isopod was fed contaminated food (100 microg benzo[a]pyrene/g dwt) for seven weeks followed by four weeks of untreated food. The hindguts of the animals were removed prior to analysis to exclude food material from the body. Benzo[a]pyrene concentrations were log-normally distributed among the individuals. The high inter-individual variation in benzo[a]pyrene content could not be explained from differences in sex, the estimated amount of food in the hindgut, or the body weight. A one-compartment model fitted to the isopod concentrations estimated an assimilation rate of 2.9 microg benzo[a]pyrene/g dwt day, an elimination rate constant of 1.1/day and an equilibrium concentration of 2.5 microg benzo[a]pyrene/g dwt. According to the model 68% of the isopod population had an equilibrium concentration between 1.0 and 7.2 microg benzo[a]pyrene/g dwt day with a benzo[a]pyrene half-life ranging between 0.4 and 1.3 days. The assimilation efficiency was estimated at 20 to 40% of the ingested benzo[a]pyrene. The tissue distribution of benzo[a]pyrene was investigated in a separate experiment. Trace levels of benzo[a]pyrene were detected in haemolymph samples, demonstrating absorption and transport of the compound in the isopod. It is concluded that dietary benzo[a]pyrene is available for uptake to the isopod and that low residues of the compound observed in field isopods are the result of a high elimination rate rather than a reduced bioavailability. As PAHs from soil appear to be available to soil invertebrates, the widespread contamination of the soil from atmospheric emissions is of some concern, especially since the observed elimination may be linked to metabolic activation of PAHs.

Degradation of Polynuclear Aromatic Hydrocarbons bySphingomonas paucimobilis

The ability of Sphingomonas paucimobilis, strain EPA 505 (a soil bacterium capable of utilizing fluoranthene as the sole source of carbon and energy for growth) to metabolize a variety of high molecular weight polynuclear aromatic hydrocarbons (PAHs) was investigated. After 16 h of incubation with 10 ppm of a PAH, a resting cell suspension (1 mg wet cells/mL) of S. paucimobilis grown on fluoranthene degraded 80.0, 72.9, 31.5, 33.3, 12.5, and 7.8% of pyrene, benz[a]anthracene (B[a]A), chrysene, benzo[a]pyrene (B[a]P), benzo[b]fluoranthene (B[b]F), and dibenz[a,h]anthracene (DB[a,h]A), respectively. No degradation of dibenzo[a,l]pyrene was detected under these conditions. 1-Nitropyrene was degraded at a lower rate than pyrene. The extent of degradation of the PAHs increased with an increase in cell density. Studies with [7-14C]B[a]P and [5,6,11,12-14C]chrysene showed that, after 48 h of incubation, the cells degraded nearly 28 and 42% of [14C]B[a]P and [14C]chrysene to 14CO2, respectively, suggesting that the bacterium is able to metabolize B[a]P and chrysene via ring cleavage. No evolution of 14CO2 was detected from cultures incubated with [4,5,9,10-14C]pyrene or [1,2,3,4,4a,4b-U-14C]dibenz[a,l]pyrene. Analysis of the ethyl acetate extracts of the culture medium by reverse-phase HPLC showed that B[a]P, B[b]F, and B[a]A were each degraded to the major, high polar metabolite(s). The degradation of B[a]P with S. paucimobilis significantly reduced the mutagenic activity associated with the hydrocarbon. The addition of solubilizing agents such as Tween 80 or cyclodextrin to the incubation medium did not enhance the biodegradation of B[a]P by EPA 505. The addition of 5 ppm of B[a]A, chrysene, fluoranthene, or DB[a,h]A to the incubation medium containing 5 ppm of B[a]P had no effect on the degradation of B[a]P by EPA 505. However, the biodegradation of B[a]P was reduced by nearly 30% in the presence of 5 ppm of B[b]F. The results demonstrate that S. paucimobilis EPA 505 has the ability to degrade several four- and five-ring PAHs ranging in molecular size, shape, and chemical structure.

Determination and genotoxicity of high molecular mass polycyclic aromatic hydrocarbons isolated from coal‐tar‐contaminated sediment

AbstractA bioassay‐directed chemical fractionation methodology was used to identify the principal mutagenic compounds in an organic solvent extract of coal‐tar‐contaminated sediment from Sydney Harbour, Nova Scotia. Biological assays with Salmonella typhimurium bacteria with the addition of oxidative metabolism indicated that the majority of the mutagenic activity observed in the sediment extract was associated with the higher molecular mass polycyclic aromatic hydrocarbons (PAHs). A normal phase high‐performance liquid chromatography (HPLC) technique was developed to separate the PAH‐rich solvent extracts into fractions containing isomeric PAHs of a single benzologue class. These fractions were analyzed by probe mass spectrometry and gas chromatography‐mass spectrometry (GC‐MS), and subjected to biological assays using strain YG1025 with the addition of oxidative metabolism (4% and 10% S9). Fractions containing compounds of molecular weights 252, 276, 278, and 302 amu exhibited mutagenic activities of 930 + 125, 510 + 100, 250 + 40, and 370 + 140 rev/mg sediment, respectively. The molecular weight 252 and 276 amu fractions were further analyzed using reversed‐phase HPLC and GC‐MS to identify the individual PAHs responsible for the observed biological activity. High molecular mass PAHs including benzo[a]pyrene, benzo[ghi]perylene, indeno[1,2,3‐cd]pyrene, and compounds of molecular weight 302 amu were found to be responsible for the majority of the mutagenic activity displayed by this complex environmental mixture.

Phylogenetic analysis of polycyclic aromatic hydrocarbon degrading mycobacteria by 16S rRNA sequencing

Mycobacterium sp. PYR-1 was previously isolated in our laboratory and was shown to be able to mineralize high molecular mass polycyclic aromatic hydrocarbons (PAHs) [ Heitkamp and Cerniglia, (1988) Appl. Environ. Microbiol. 54, 1612–1614]. In this research, the 16S rRNA gene (rDNA) of this strain was amplified by polymerase chain reaction (PCR) and directly sequenced by cycle sequencing method. We compared this sequence with all known mycobacterial 16S rDNA sequences available from GenBank and found that Mycobacterium sp. PYR-1 16S rDNA differs from the other mycobacteria, especially in the region of nucleotides 168–200 (in the Escherichia coli numbering system). Using the 16S rDNA sequences of the mycobacteria, a phylogenetic tree was constructed. The data from the phylogenetic tree and similarity values suggest that Mycobacterium sp. PYR-1 is closer to M. aurum and M. vaccae. Using the same approach, we also determined the 16S rDNA from an another PAH-degrading Mycobacterium sp. PAH135, isolated by Grosser and colleagues (1991) (Appl. Environ. Microbiol. 57, 3462–3469). Mycobacterium sp. PAH135 was found to be closer to M. aichiense, and different from our Mycobacterium sp. PYR-1.

Phylogenetic analysis of polycyclic aromatic hydrocarbon degrading mycobacteria by 16S rRNA sequencing

Mycobacterium sp. PYR-1 was previously isolated in our laboratory and was shown to be able to mineralize high molecular mass polycyclic aromatic hydrocarbons (PAHs) [Heitkamp and Cerniglia, (1988) Appl. Environ. Microbiol. 54, 1612–1614]. In this research, the 16S rRNA gene (rDNA) of this strain was amplified by polymerase chain reaction (PCR) and directly sequenced by cycle sequencing method. We compared this sequence with all known mycobacterial 16S rDNA sequences available from GenBank and found that Mycobacterium sp. PYR-1 16S rDNA differs from the other mycobacteria, especially in the region of nucleotides 168–200 (in the Escherichia coli numbering system). Using the 16S rDNA sequences of the mycobacteria, a phylogenetic tree was constructed. The data from the phylogenetic tree and similarity values suggest that Mycobacterium sp. PYR-1 is closer to M. aurum and M. vaccae. Using the same approach, we also determined the 16S rDNA from an another PAH-degrading Mycobacterium sp. PAH135, isolated by Grosser and colleagues (1991) (Appl. Environ. Microbiol. 57, 3462–3469). Mycobacterium sp. PAH135 was found to be closer to M. aichiense, and different from our Mycobacterium sp. PYR-1.

Contamination of bela krajina, Slovenia with polychlorinated biphenyls 1. Levels of some high molecular chlorinated hydrocarbons in the water and fish of the Kupa River in Croatia

It is well documented that synthetic chlorinated hydrocarbon residues are widespread throughout the world ecosystem.

The Importance of Long and Short-Term Air-Soil Exchanges of Organic Contaminants

Retrospective analysis of archived soil samples collected and stored from long-term agricultural experiments in the UK has shown how soil organic chemical composition has changed over time. High molecular weight polycyclic aromatic hydrocarbons (e.g. benzo[a]pyrene) and polychlorinated dibenzo-p-dioxins and -furans have increased in concentration through this century as a result of cumulative atmospheric depositional inputs. Concentrations of polychlorinated biphenyls and low molecular weight hydrocarbons (e.g. phenanthrene) peaked in the late 1960s/early 1970s, but have declined subsequently. This reflects declining atmospheric inputs of these compounds and losses from surface soils by volatilisation back to the atmosphere and biodegradation. PCBs and low molecular weight PAHs exist predominantly in the vapour phase in air, whilst heavy PAHs and PCDD/Fs are predominantly particulate-bound. Outgassing from soils is probably the most important contemporary source of PCBs to the atmosphere in the UK. Future UK PCB air concentrations will presumably therefore be influenced (controlled) by the rate of desorption and outgassing, as soil and air concentrations move towards a condition of equilibrium partitioning. Archived soils collected and stored before the commercial manufacture of PCBs contain no PCBs indicating that there is no 'natural production' of these compounds. However, within a few hours of exposure to contemporary air these samples contain detectable quantities of PCBs. Short-term air-soil exchange, such as during soil drying in the laboratory, can lead to contamination of samples which contain low concentrations of PCBs and loss from samples which contain high concentrations.

High Molecular Weight Polycyclic Aromatic Hydrocarbons in Hydrothermal Petroleums-Indicators of High Temperatures and Water Washing: ABSTRACT

Hydrothermal petroleums from active sedimented oceanic spreading axes contain polycyclic aromatic hydrocarbons (PAH) as characteristic components of their rapid high temperature genesis. The unsubstituted PAH dominate over their alkyl-substituted homologs and occur at high concentrations relative to the aliphatic components, which distinguishes hydrothermal petroleums from conventional reservoir petroleums. Some of the samples contain PAH with higher molecular weights than coronene (M.W. 300) and here we describe the structures and distributions of these PAH in typical examples of petroleums from Guaymas Basin, Escanaba Trough and Middle Valley. Some of the aromatic fractions (F2) show PAH of up to nine rings [e.g., dibenzo-(e,ghi)perylene, benzo(a)coronene, benzo(pqr)naphtho(8,1,2-bcd)perylene, naphtho(8,1,2-abc)coronene]. Fraction 3 in some of these samples has ovalene, a condensed ten-ring PAH. These PAH are the most thermodynamically stable structures for each ring number, and are most likely indicative of a one-ring build-up mechanism. The samples also contain a few specific PAHs [e.g., the seven-ring PAH dibenzo(cd,lm)perylene] which are not members of this stable class. Its formation mechanism must be very specific through the condensation of a pair of the three-ring phenalene radicals or through the Scholl-condensation of pyrene to a nine-ring PAH with its subsequent hydrogenation and cracking down to dibenzo(cd,lm)-perylene. This is themore » first report of the occurrence of heavy PAH (M.W. >300) in geological samples. They are concentrated in the bitumens by removal of the lower molecular weight PAH due to mixing during hydrothermal fluid/oil transport and selective deposition/solidification of the heavy ends at the seabed with concurrent loss of the more water soluble and lower weight products to the ambient seawater. Additional post-depositional reworking by hot fluids and biodegradation further enhance the enrichment of the heavy PAH.« less

Levels of some high molecular chlorinated hydrocarbons in sediment samples from the eastern Adriatic coastal waters

It is well documented that synthetic chlorinated hydrocarbon residues are widespread through the oceanic ecosystem. The Adriatic Sea, as semi-enclosed body of water, is of special interest for an evaluation of the entry, extent and fate of the pollution by chlorinated hydrocarbons. Sediments samples were collected from 1976 to 1990 at seven areas and over forty stations located on the eastern Yugoslav coastal waters. Concentrations of chlorinated insecticides and polychlorinated biphenyls in surface sediment samples ranged from <0.1 to 93.9 for DDTs and from <0.5 to 294 μg kg−1 for PCBs on dry weight basis. It is very important to stress that all these samples were analyzed from a single analytical group (mostly by the same analyst), using a uniform methodology. Total DDT and PCB concentration do not exhibit Gausian distribution in the investigated area and collecting period, so it is necessary to be very careful in interpreting the concentration data using parametric statistics. Very often, the pollutant levels in sediment samples differ significantly in samples collected at the same time at nearby stations.

Geology and geochemistry of source rocks of the Eastern Pearl River Mouth Basin, South China Sea

The Pearl River Mouth Basin (PRMB), with mostly Cenozoic sediments, is one of the largest offshore oil-bearing basins in the South China Sea. It covers an area of 175,000 km 2 with the maximum sedimentary thickness of 12 km. Large structural belts trending NE-SW were developed in the basin. From north to south they are the Northern Fault Terrace-Uplift, Northern Depression, Central Uplift and Southern Depression Belts, respectively. The evolution of the PRMB had been in two stages, i.e. first faulting (from Paleocene to Early Oligocene) and then subsiding (starting from Late Oligocene), and the so-called Double Structural Layers were thus developed. Therefore, the sedimentary rocks of the PRMB are characterized by terrestrial followed by marine facies. Three terrestrial (accendingly known as Shenhu, Wenchang and Enping Formations, respectively) and six marine formations (accending named Zhuhai, Zhujiang, Yuehai, Wanshan and Quaternary Formations, respectively) were deposited. Geochemical statistical study of possible source rocks in the PRMB showed that both the terrestrial Enping and Wenchang Formations were richer in organic matter while both the marine Zhujiang and Zhuhai Formations are relatively poor. The type of organic matter is dominantly composed of Types II to I for the Wenchang Formation and mainly Type III for the other three overlying formations. Furthermore, in thermal maturity, the Zhujiang Formation is either immature or marginally mature, Zhuhai, marginally mature-mature, Enping, mature-highly mature and Wenchang, highly-overmature. Hence, the principal source rocks in the PRMB are the Wenchang and Enping Formations, and the Zhuhai and Zhujiang Formations could also be oil sources. Geochemical investigations indicated that the source rocks in the PRMB are characterized by lower saturates to aromatics ratio, commonly found 18a(H)-oleanane and resin-derived “W” and “T” compounds in some source rocks, enriched high molecular weight n-paraffin hydrocarbons and C29 steranes except for those of Wenchang and partly of the Enping Formations and predominant C30 hopane for Wenchang Formation in contrast to the others, which contained either predominant C31 homohopane or C29 norhopane or C27 trisnorhopane. However, the more abundant C30 4-methyl steranes discovered in crude oils of the PRMB were only identified from a thin setting of Wenchang Formation occurring in Huilu Lowhigh. Therefore, it was deduced that there must have been a certain setting of the Wenchang Formation which contains enriched C30 4-methylsteranes which are widely distributed in the depositional centers of the separated Depressions of the PRMB. They are possible oil sources of the reservoirs found in the PRMB.

Interaction of MeV ions and VUV photons with polymers and high molecular hydrocarbons

Organic solids such as polymethylene, polyethylene, polyoxymethylene, aliphatic and cyclic paraffins, naphthalene, anthracene and kerogen were irradiated at 77 K with 10–20 MeV cyclotron ions (p, 3He) and up to 10 eV photons. The products were analysed by quadrupole mass spectrometry (QMS). Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy and gas chromatography (GC). Besides radiolytic fragmentation, also synthesis of new and complex compounds was observed as a consequence of hot carbon chemistry. Vacuum ultraviolet (VUV) irradiation proved to be less effective in the buildup of new structures than MeV ions, due to its lower linear energy transfer.

High-temperature GC/MS characterization of porphyrins and high molecular weight saturated hydrocarbons

Determination of the exact structure and relative concentrations of metalloporphyrins and high molecular weight cyclic and acyclic hydrocarbon is of importance since these are useful «biomarkers» in petroleum exploration. Description of the recent efforts in high-temperature gas chromatography /electron impact mass spectrometry (GC/EIMS) and gas chromatography/field ionisation mass spectrometry (GC/FIMS) analysis of these relatively high molecular weight components in petroleum and petroleum sediments