The effect of petroleum hydrocarbons on reproduction of an estuarine planktonic copepod in laboratory cultures

The effect of short-term exposure to high concentration (mg l.^?1) of water soluble fraction of aromatic heating oil on subsequent egg production by the estuarine copepod Eurytemora affinis has been studied in laboratory cultures to investigate possibly sublethal biological effects following exposure to hydrocarbon under an oil spill. Significant reduction in subsequent length of life, total number of eggs produced, mean brood size, and rate of egg production was observed. Exposure to naphthalene alone at 1 mg l.^?1 for 24 h produced a significant effect on total fecundity of the females. Ingestion rates were significantly lower when measured in the presence of the water soluble fraction, and also naphthalene alone at mg l.^?1 concentrations. Exposure to low-levels (10 and 50 μg l.^?1) of ¹⁴C-naphthalene alone over a period of ten days produced no significant effect on feeding or reproduction despite the high concentrations of hydrocarbon accumulated during this period. The results are discussed in relation to previous work on the fate of hydrocarbons in planktonic copepods, using ¹⁴C-1-naphthalene as a model compound.     

Der Einfluß von Erdölkohlenwasserstoffen auf die Primärproduktion des Donauplanktons

Danube river water samples were saturated with mineral oil, and then the primary production (gross) was determined by means of the light-dark bottle method (oxygen) in situ at depths of 0.1… 1.5 m in comparison with untreated samples. Samples were exposed for half a solar day alternately during the first and second half-days. Investigations carried out between March and October for periods of 14 days showed a mean production of 2.56 g · m^?2d^?1 O₂, which was reduced by 36% due to 12.6 mg/l hydrocarbons. Production decreases with the water depth from 6.2 to 0.9 mg · l^?1d^?1 0₂, whereas the inhibition by hydrocarbons increases from 31 to 41%.     

Study of genetic evolution of oil inclusion and density of surface oil by measurement of fluorescence lifetime of crude oil and oil inclusion

By using fluorescence lifetime image microscope (FLIM) and time-correlated single photon counting (TCSPC) technique, we measured fluorescence lifetime of crude oils with density of 0.9521–0.7606 g/cm³ and multiple petroleum inclusions from Tazhong uplift of Tarim Basin. As indicated by the test results, crude oil density is closely correlated with average fluorescence lifetime following the regression equation Y=–0.0319X+0.9411, which can thus be used to calculate density of oil inclusions in relation to fluorescence lifetime and density of corresponding surface crude. For type A oil inclusions showing brown-yellow fluorescence from Tazhong 1 well in Tarim Basin, their average fluorescence lifetime was found to be 2.144–2.765 ns, so the density of surface crude corresponding to crude trapping these oil inclusions is 0.852–0.873 g/cm³, indicating that they are matured oil inclusions trapped at earlier stage of oil formation. For type B oil inclusions with light yellow-white fluorescence, their average fluorescence lifetime was found to be 4.029–4.919 ns, so the density of surface crude corresponding to crude trapping these oil inclusions is 0.784–0.812 g/cm³, indicating that they are higher matured oil inclusions trapped at the second stage of oil formation. For type C oil inclusions showing light blue-green fluorescence, their average fluorescence lifetime was found to be 5.063–6.168 ns, so the density of surface crude corresponding to crude trapping these oil inclusions is 0.743–0.779 g/cm³, indicating that they are highly-matured light oil inclusions trapped at the third stage of oil formation.     

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

Aromatic hydrocarbons are generally main distillation of crude oil and organic extract of source rocks. Bicyclic and tricyclic aromatic hydrocarbons can be purified by two-step method of chromatography on alumina. Carbon isotopic composition of individual aromatic hydrocarbons is affected not only by thermal maturity, but also by organic matter input, depositional environment, and hydrocarbon generation process based on the GC-IRMS analysis of Upper Ordovician, Lower Ordovician, and Cambrian source rocks in different areas in the Tarim Basin, western China. The subgroups of aromatic hydrocarbons as well as individual aromatic compound, such as 1-MP, 9-MP, and 2,6-DMP from Cambrian-Lower Ordovician section show more depleted 13 C distribution. The 13 C value difference between Cambrian-Lower Ordovician section and Upper Ordovician source rocks is up to 16.1‰ for subgroups and 14‰ for individual compounds. It can provide strong evidence for oil source correlation by combing the 13 C value and biomarker distribution of different oil and source rocks from different strata in the Tarim Basin. Most oils from Tazhong area have geochemical characteristics such as more negative 13C9-MP value, poor gammacerane, and abundant homohopanes, which indicate that Upper Ordovician source rock is the main source rock. In contrast, oils from Tadong area and some oils from Tazhong area have geochemical characteristics such as high 13C9-MP value, abundant gammacerane, and poor homohopanes, which suggest that the major contributor is Cambrian-Lower Ordovician source rock.     

222Rn as Natural Tracer for LNAPL Recovery in a Crude Oil‐Contaminated Aquifer

The objective of this study was to investigate whether ²²²Rn in groundwater can be used as a tracer for light non‐aqueous phase liquid (LNAPL) quantification at a field site treated by dual‐phase LNAPL removal. After the break of a pipeline, 5 ha of soil in the nature reserve Coussouls de Crau in southern France was contaminated by 5100 m³ of crude oil. Part of this oil seeped into the underlying gravel aquifer and formed a floating oil body of about 3.9 ha. The remediation consists of plume management by hydraulic groundwater barriers and LNAPL extraction in the source zone. ²²²Rn measurements were performed in 21 wells in and outside the source zone during 15 months. In uncontaminated groundwater, the radon activity was relatively constant and remained always >11 Bq/L. The variability of radon activity measurements in wells affected by the pump‐and‐skim system was consistent with the measurements in wells that were not impacted by the system. The mean activities in wells in the source zone were, in general, significantly lower than in wells upgradient of the source zone, owing to partitioning of ²²²Rn into the oil phase. The lowest activities were found in zones with high non‐aqueous phase liquid (NAPL) recovery. LNAPL saturations around each recovery well were furthermore calculated during a period of high groundwater level, using a laboratory‐determined crude oil–water partitioning coefficient of 38.5 ± 2.9. This yielded an estimated volume of residual crude oil of 309 ± 93 m³ below the capillary fringe. We find that ²²²Rn is a useful and cheap groundwater tracer for finding zones of good LNAPL recovery in an aquifer treated by dual‐phase LNAPL removal, but that quantification of NAPL saturation using Rn is highly uncertain.     

Application of pyrolysis gas chromatography technique to evaluation of coal-generated hydrocarbon

Based on kerogen-generated hydrocarbon model, a new method to calculate hydrocarbon yields for coals and coaly samples was put forward by means of pyrolysis technique. At the same time, the empirical criteria suggested by Powell were revised. The threshold value was preliminarily defined as HC yields >30 mg HC per gram TOC for effective gas source rocks and >60 mg HC per gram TOC for effective oil source rocks. Additionally, it was also confirmed that the relative compositions of the three ranges of C1-C5 total hydrocarbons, C6-C14n-alkanes plusn-alkenes and C15⁺ n-alkanes plusn-alkenes from pyrolysates can be effectively used to distinguish the coal-generated hydrocarbon types.     

Geochemical evolution during the cracking of crude oil into gas under different pressure systems

Two comparative simulation experiments(a normal atmospheric-pressure opening system and a 20 MPa closed system)were conducted to study the geochemical evolution of n-alkane,sterane,and terpane biomarkers in the process of oil cracking into gas under different pressures.With an initial experimental temperature set at 300°C,the temperature was increased to 650°C at a heating rate of 30°C/h.The products were tested every 50°C starting at 300°C,and a pressure of 20 MPa was achieved using a water column.The low-maturity crude oil sample was from the Paleogene system in the Dongying sag in eastern China.The threshold temperature obtained for the primary oil cracking process in both pressure systems was 450°C.Before the oil was cracked into gas,some components,including macromolecular n-alkanes,were cracked into medium-or small-sized n-alkanes.The secondary oil cracking of heavy hydrocarbon gases of C2–5to methane mainly occurred between 550°C to 650°C,and the parameters Ln(C1/C2)and Ln(C1/C3),as well as the dry coefficients,increased.Overpressure inhibited the oil cracking process.In the 20 MPa system,the oil conversion rate decreased,the temperature threshold for gas generation rose,and oil cracking was inhibited.Compared with the normal pressure system,high-carbon n-alkanes and other compounds in the 20 MPa pressure system were reserved.Furthermore,the parameters∑C21-/∑22+,Ln(C1/C2),and Ln(C1/C3),as well as the dry coefficients,decreased within the main temperature range.During secondary oil cracking(550°C to 600°C),the Ph/nC18and Pr/nC17decreased.High pressure influenced the evolution of the biomarkers Ts and Tm,C31homohopane,C29sterane,and their related maturity parameters to different extents during oil cracking under different temperature ranges.     

Cracking conditions of crude oil under different geological environments

There are mainly 3 kinds of existing states of oil generating from source rocks, that is, dispersive liquid hydrocarbon inside of source rock, dispersive liquid hydrocarbon outside of source rock and concentrated liquid hydrocarbon outside of source rock. Because of the differences in thermal history and medium conditions around, and the interaction of organic and inorganic matter, the liquid hydrocarbon with 3 kinds of existing state has different cracking conditions. The gas generation dynamics experiments of crude oil matching different mediums indicate that the distribution of activation energy of methane changes a lot according to medium difference. The carbonate has a main influence on oil cracking conditions and can largely reduce its activation energy, which reflects the lower cracking temperature of crude oil. The mudstone takes a second place and the sandstone is the smallest. The catalytic cracking function to the oil of the carbonate, of the mudstone and of the sandstone changes weaken in turn. The corresponding R _o values of main gas generation period in different mediums are as follows: 1.5%–3.8% with pure crude oil, 1.2%–3.2% with dispersive crude oil in carbonate, 1.3%～3.4% with dispersive crude oil in mudstone and 1.4%–3.6% with dispersive crude oil in sandstone. The influence of pressure to crude oil cracking is relatively complicated. In the low heating speed condition, pressure restrains the oil cracking and gas generation, but in the high heating speed condition, pressure has an indistinctive influence to the oil cracking and gas generation. Pressure also makes a different effort in different evolvement stage. Taking the middle and lower Cambrian source rocks in the Tarim Basin as an example, primary oil generating quantity is 2232.24×10⁸t, residual oil and oil cracking gas quantity is 806.21×10⁸t and 106.95×10¹²m³ respectively.     

The tritium and carbon-14 profiles at the Geosecs I (1969) and GOGO I (1971) North Pacific stations

Tritium and¹⁴C data of the “GOGO I” station at 28.5°N, 121.6°W in November 1971 are reported. The tritium decline between 150 and 350 m depth is as pronounced as was observed on a previous occupation of the same position, station “Geosecs I” in September 1969, and the tritium concentrations below 200 m are unchanged.¹⁴C data from the depth range of tritium decline are corrected for fallout¹⁴C contribution. The correcting procedure requires simultaneous measurements of¹⁴C, ΣCO₂, and tritium. It is concluded that the natural absolute¹⁴C concentration attains a maximum near 400 m depth, of 7.5% excess over that of surface water.     

Annual growth rings in a sample of Paraná pine (Araucaria angustifolia): Toward improving the 14C calibration curve for the Southern Hemisphere

This work reports the first high-precision ¹⁴C-AMS dating of holocellulose from a Brazilian subtropical species for the period 1927–1997, with the goal to identify suitable Southern American tree species that will serve as benchmarks for improving the calibration of the ¹⁴C time-scale for the Southern Hemisphere (SH). The tree rings analyzed here came from a single tree of Paraná pine (Araucaria angustifolia) growing at 22°50′S, 46°04′W (Camanducaia, Minas Gerais, Brazil). A slight depletion of atmospheric ¹⁴C after 1927 AD was observed, due to the Suess effect. Our ¹⁴C results also showed the rise and rapid decrease of atmospheric ¹⁴C concentrations associated with the detonation of nuclear weapons during the late 50s, and its subsequent uptake by other large C sinks. Current ¹⁴C data can be used for the study of the global carbon cycle, forensic sciences applications, and the determination of the age and growth rate of tropical trees without annual ring patterns. The remarkable overall agreement of our tree-ring/¹⁴C data with the SH Zone 1–2 compilation dataset shows this subtropical tree species' potential to refine the ¹⁴C calibration curve.     

Dissolved/dispersed hydrocarbons,tarballs and the surface microlayer: Experiences from an IOC/UNEP Workshop in Bermuda,December, 1984

An intercomparison exercise was conducted at the Bermuda Biological Station for Research, Inc, Bermuda on 1–15 December 1984. It primarily involved the testing of the IOC Manual for monitoring oil and dissolved/dispersed petroleum hydrocarbons (DDPH) in marine waters and on beaches (IOC, Manuals and Guides, No. 13). An additional exercise sought to intercompare methodologies for the collection of sea surface microlayer samples.DDPH measurements in the inshore waters of Bermuda resulted in a mean concentration of 0.057 μg l⁻¹ of (n = 30) chrysene equivalents with a 60% relative standard deviation (RSD). Open ocean samples yielded a mean concentration of 0.011 μg l⁻¹ (n = 44) with a 65% RSD. These concentrations are extremely low and the results indicate that the method described in the Manual is sufficiently sensitive for the detection of ‘hot spots’The collection of beach tar using the method outlined in the Manual indicated that the data, when expresed as per metre of linear beach length, are an extremely good measure of oil contamination. The mean of 42 collections was 23.1 ± 14.4 g m⁻¹ in the first sampling period and the mean of 39 transects was 40.6 ± 17.7 g m⁻¹ on the second sampling period. Although 14 individuals took part in the sampling the results of individuals were consistent enough to demonstrate that beach tar collections are indeed valuable tools for monitoring contamination by petroleum in the marine environment.The operational manual for the sampling of the sea surface microlayer (IOC Manuals and Guides, No. 15), was also tested. The results indicated that this method collects reproduceable volumes of elevated concentrations of materials from the sea surface suitable at least for qualitative analyses. However, the spatial distribution and stability of surface films may render quantitative analyses less meaningful.     

Petroleum source rock identification of United Kingdom Atlantic Margin oil fields and the Western Canadian Oil Sands using Platinum,Palladium, Osmium and Rhenium: Implications for global petroleum systems

This study demonstrates that petroleum and source rocks are enriched in Pt and Pd to the ppb level, and that the ¹⁸⁷Os/¹⁸⁸Os composition coupled with the Pt/Pd value permits the fingerprinting of petroleum to its source. Oils from the United Kingdom Atlantic Margin (sourced from the Upper Jurassic Kimmeridge Clay Fm.) as well as source rock samples have been analysed for Pt and Pd. When the Pt/Pd value is compared with ¹⁸⁷Os/¹⁸⁸Os (calculated at the time of oil generation; Os_g) the values from both the known source and the oils are similar, demonstrating that they can be used as an oil to source fingerprinting tool. This inorganic petroleum fingerprinting tool is particularly important in heavily biodegraded petroleum systems where traditional fingerprinting techniques (e.g. biomarkers) are severely hampered, e.g. the world's largest oil sand deposit, the West Canadian Oil Sands (WCOS). This has caused the source of the WCOS to be hotly debated, with no present day consensus between inputs from potential source units e.g. Exshaw and Gordondale Fms. ¹⁸⁷Os/¹⁸⁸Os and Pt/Pd fingerprinting of the oil sands shows that the majority of the petroleum have similar ¹⁸⁷Os/¹⁸⁸Os and Pt/Pd values, supporting the hypothesis of one principal source. Analysis of the potential source rocks establishes that the principal source of the oil sands to be from the Jurassic Gordondale Fm., with a minor Exshaw Fm. input. Thus, the combination of previously pioneered Re–Os petroleum geochronology with ¹⁸⁷Os/¹⁸⁸Os and Pt/Pd values of petroleum permits both a temporal and spatial understanding of petroleum systems.     

中国新疆博斯腾湖现代碳库效应研究

碳库效应存在影响了¹⁴C测年的准确性,制约了沉积物在湖泊研究中的应用。本文研究位于典型西风环流带的新疆博斯腾湖现代碳库效应,结合同位素地球化学、水化学等方法,探讨了博斯腾湖碳库效应的影响机制。研究结果表明,博斯腾湖最大现代碳库年龄为3535年,最小为现代碳,集中在670~945年。而过去碳库效应集中在1033~2200年。深水区表现为碳库年龄较小且稳定;在入湖口碳库效应最大,富水生植物浅水区碳库效应最小。与过去碳库年龄相比较,现代碳库效应整体表现更为年轻。研究发现,博斯腾湖口受流域外源“死”碳影响,深水区受湖水与大气CO₂交换率差异影响,富水生植物浅水区可能受水生植物光合作用影响。此外,核爆效应也对博斯腾湖现代碳库效应产生了影响,可能导致最高约1000年的年代误差。利用深水区放射性碳比活度(pMC)平均值与大气碳比活度差值(~18%),得出深水区沉积物存在约846年现代碳库效应,再经核爆效应校正后得出博斯腾湖存在最高约1800年碳库效应。     

Radiocarbon: A chronological tool for the recent past

The past few hundred years have seen large fluctuations in atmospheric ¹⁴C concentration. In part, these have been the result of natural factors, including the climatic changes of the Little Ice Age, and the Spörer and Maunder solar activity minima. In addition, however, changes in human activity since the middle of the 19th century have released ¹⁴C-free CO₂ to the atmosphere. Moreover, between c. 1955 and c. 1963, atmospheric nuclear weapon testing resulted in a dramatic increase in the concentration of ¹⁴C in the atmosphere. This was followed by a significant decrease in atmospheric ¹⁴C as restrictions on nuclear weapon testing began to take effect and as rapid exchange occurred between the atmosphere and other carbon reservoirs. The large fluctuations in atmospheric ¹⁴C that occurred prior to 1955 mean that a single radiocarbon date may yield an imprecise calibrated age consisting of several possible age ranges. This difficulty may be overcome by obtaining a series of ¹⁴C dates from a sequence and either wiggle-matching these dates to a radiocarbon calibration curve or using additional information on dated materials and their surrounding environment to narrow the calibrated age ranges associated with each ¹⁴C date. For the period since 1955 (the bomb-pulse period), significant differences in atmospheric ¹⁴C levels between consecutive years offer the possibility of dating recent samples with a resolution of from one to a few years. These approaches to dating the recent past are illustrated using examples from peats, lake and salt marsh sediments, tree rings, marine organisms and speleothems.     

Carbon isotopic compositions of 1,2,3,4-tetramethylbenzene in marine oil asphaltenes from the Tarim Basin: Evidence for the source formed in a strongly reducing environment

Although 1-alkyl-2,3,6-trimethylbenzenes and a high relative amount of 1,2,3,4-tetramethylbenzene have been detected in marine oils and oil asphaltenes from Tabei uplift in the Tarim Basin, their bio-logical sources are not determined. This paper deals with the molecular characteristics of typical ma-rine oil asphaltenes from Tabei and Tazhong uplift in the Tarim Basin and the stable carbon isotopic signatures of individual compounds in the pyrolysates of these asphaltenes using flash pyrolysis-gas chromatograph-mass spectrometer (PY-GC-MS) and gas chromatograph-stable isotope ratio mass spectrometer (GC-C-IRMS), respectively. Relatively abundant 1,2,3,4-tetramethylbenzene is detected in the pyrolysates of these marine oil asphaltenes from the Tarim Basin. δ 13C values of 1,2,3,4-tetrame-thylbenzene in the pyrolysates of oil asphaltenes vary from-19.6‰ to-24.0‰, while those of n-alkanes in the pyrolysates show a range from-33.2‰ to-35.1‰. The 1,2,3,4-tetramethylbenzene in the pyro-lysates of oil asphaltenes proves to be significantly enriched in 13C relative to n-alkanes in the pyro-lysates and oil asphaltenes by 10.8‰―15.2‰ and 8.4‰―13.4‰, respectively. This result indicates a contribution from photosynthetic green sulfur bacteria Chlorobiaceae to relatively abundant 1,2,3,4-tetramethylbenzene in marine oil asphaltenes from the Tarim Basin. Hence, it can be speculated that the source of most marine oil asphaltenes from the Tarim Basin was formed in a strongly reducing water body enriched in H2S under euxinic conditions.     

Superhydrophobic and superoleophillic surface of porous beaded electrospun polystrene and polysytrene-zeolite fiber for crude oil-water separation

This research presents a cheap route procedure for the preparation of a potential adsorbent with superhydrophobic/superoleophillic properties for selective removal of crude oil from water. In this study, expanded polystyrene (EPS) was electrospun to produce beaded fibers in which zeolite was introduced to the polymer matrix in order to impart rough surface to non-beaded fiber. Films of the EPS and EPS/Zeolite solutions were also made for comparative study. The electrospun fibers EPS, EPS/Zeolite and resultant films were characterized using SEM, BET, FTIR and optical contact angle. The fibers exhibited superhydrophobic and superoleophillic wetting properties with water (>150⁰) and crude oil (0⁰). The selective removal of crude oil presents new opportunity for the re-use of EPS as adsorbent in petroleum/petrochemical industry.     

Organic carbon release by phytoplankton and bacterial reassimilation

The release of organic carbon by phytoplankton and its reassimilation by bacteria were studied in Lake Geneva during four daily kinetics, using¹⁴C techniques. Gentamycin was used to suppress bacterial activity. Size fractionation was used to measure¹⁴C fixation in 2 particulate fractions (≥1 μm and 0.2 to 1 μm) and in a third fraction: dissolved organic carbon. Measurements of bacterial biomass and¹⁴C glucose uptake as the H¹⁴CO ₃ ⁻ uptake by samples prefractionated before incubation showed that the whole algae were retained on 1 μm pore size Nuclepore filters, but bacteria were retained on 1 μm and 0.2 μm filters. Concentration of 20 μg.ml⁻¹ gentamycin resulted in incomplete bacterial inhibition while phytoplankton was affected. Phytoplankton released less of 20% of its photoassimilated carbon of which a large proportion was utilized by bacterioplankton.     

Towards radiocarbon calibration beyond 28 ka using speleothems from the Bahamas

We present a new speleothem record of atmospheric Δ¹⁴C between 28 and 44 ka that offers considerable promise for resolving some of the uncertainty associated with existing radiocarbon calibration curves for this time period. The record is based on a comprehensive suite of AMS ¹⁴C ages, using new low-blank protocols, and U–Th ages using high precision MC-ICPMS procedures. Atmospheric Δ¹⁴C was calculated by correcting ¹⁴C ages with a constant dead carbon fraction (DCF) of 22.7 ± 5.9%, based on a comparison of stalagmite ¹⁴C ages with the IntCal04 (Reimer et al., 2004) calibration curve between 15 and 11 ka. The new Δ¹⁴C speleothem record shows similar structure and amplitude to that derived from Cariaco Basin foraminifera (Hughen et al., 2004, 2006), and the match is further improved if the latter is tied to the most recent Greenland ice core chronology (Svensson et al., 2008). These data are however in conflict with a previously published ¹⁴C data set for a stalagmite record from the Bahamas — GB-89-24-1 (Beck et al., 2001), which likely suffered from ¹⁴C analytical blank subtraction issues in the older part of the record. The new Bahamas speleothem ?¹⁴C data do not show the extreme shifts between 44 and 40 ka reported in the previous study (Beck et al., 2001). Causes for the observed structure in derived atmospheric Δ¹⁴C variation based on the new speleothem data are investigated with a suite of simulations using an earth system model of intermediate complexity. Data-model comparison indicates that major fluctuations in atmospheric ?¹⁴C during marine isotope stage 3 is primarily a function of changes in geomagnetic field intensity, although ocean–atmosphere system reorganisation also played a supporting role.     

Radiocarbon in polar ice: The mechanism by which radiocarbon is preserved in firn grains

This work is devoted to the problem of localizing the ¹⁴C cosmogenic radionuclide in a firn layer covering glaciers. The data on ¹⁴C in ice samples from the GISP2 ice core drilled on a Greenland ice dome (Summit) are analyzed. It has been indicated that experimental values of the ¹⁴C concentration are systematically smaller than theoretically calculated values, which indicates that firn grains partially lose ¹⁴C. Diffusion of cosmogenic ¹⁴C in firn grains and hydration of ¹⁴CO₂ in a disordered ice layer, which is formed on a firn grain surface and at the boundary between ice monocrystals, are considered. It has been indicated that these processes are among the main ones responsible for the level of radiocarbon concentration in firn and ice samples.