Hydrocarbons in coastal sediments from the Mediterranean sea (Gulf of Fos area, France)

Sedimentary hydrocarbons have been studied quantitatively and qualitatively in 11 coastal stations located in the Gulf of Fos (French Mediterranean coast). Hydrocarbon levels ranged from 10 to 260 mg kg(-1) sed. dry weight. A new parameter "NAR" (Natural n-alkane ratio) is proposed to evaluate the contribution of terrestrial inputs of hydrocarbons in the sediments. The origins of hydrocarbons are multiple: terrestrial inputs, biogenic, pyrolytic (industry emissions mainly steel and iron industries, ship and road traffic). Generally, the main source of contamination is not petroleum. Several ratios between parent polycyclic aromatic hydrocarbons show that the sources of hydrocarbons in the sediments are generally much more pyrolytic than petrogenic.     

On saturation of magnesian cordierite with alkanes at high temperatures and pressures

 Incorporation of hydrocarbons (CH₄, C₂H₆, C₃H₈, C₄H₁₀) in cordierite channels was experimentally studied at 700 °C and at pressures from 200 to 1000 MPa, (avoiding recrystallization). The maximum concentrations of hydrocarbons determined by gas chromatographic analysis are CH₄=78.3, C₂H₆=134, C₂H₄ + C₂H₆=26, C₃H₈=28, C₄H₁₀=32, C₅H₁₂=23, and C₆H₁₄=7 × 10⁻³ wt%). According to IR spectroscopy data, the channel forms of hydrocarbons differ from the forms on the surface. As a result of interactions with the framework oxygen, normal hydrocarbons are converted to saturated oligomers and their fragments. Small amounts of water molecules of the first and second types (up to 0.3 wt%) are formed in the same way. As pressure grows from 200 to 1000 MPa, the total content of structural hydrocarbons is nearly doubled. Special runs on cordierite saturation in mixtures of hydrocarbons with water showed that low contents of hydrocarbons in natural cordierites correspond to their large concentrations in fluid. Received: 7 May 2001 / Accepted: 17 July 2001     

海洋中烃的分析方法

本文介绍海洋中烃的提取和分析方法，以及部分海域海水中烃的分析结果．     

Simultaneous measurements of ozone and its precursors on a diurnal scale at a semi urban site in India

Simultaneous observations of surface ozone (O₃) with its precursors namely, carbon monoxide (CO) and oxides of nitrogen (NO_x) have been taken on diurnal scale from a tropical semi-urban site, Pune (18.54°N, 73.81°E) in India. We present the data for one year (2003–2004) period to study the salient features of these trace gases. The peak in amplitude of ozone is found during the noontime whereas in CO and NO_X it is observed in the morning hours between 0800 and 0900 H. The concentration of these pollutants drop down considerably during southwest monsoon months and the diurnal pattern also become very weak. The diurnal trends of these gases are found to be different for different seasons, which are specific to the receptor site. Model simulations using 3-D chemical-transport model with regional emission inventories and observed winds have also been carried out. The comparison of model results with observations, on seasonal basis yielded a reasonable qualitative agreement. The relative role of local emissions and long range transport in the diurnal pattern for different seasons has been outlined, which reveals that the ozone is highly influenced by regional/long range transport in this region. The effect of precursor amounts in the morning on afternoon ozone peak levels has been investigated using the lag correlation study, which reveals that a time lag of 5–7 h is required for most of these precursor gases to photo-chemically produce ozone to its maximum potential. Results are discussed in the light of available topographic and meteorological conditions.     

Adsorptive Separation of 1, 2‐Dichloroethane from Model Wastewater by Natural Clinoptilolite

The adsorptive separation of 1, 2‐dichloroethane from model wastewater by different Slovak natural and octadecylammonium‐modified clinoptilolites has been studied. It was found that the 1, 2‐dichloroethane will be adsorbed by natural as well as by surfactant‐modified clinoptilolites; all clinoptilolites have a similar adsorption loading. There was also no remarkable difference between the natural and surfactant‐modified clinoptilolites in respect to the adsorption kinetics.     

Feinauflösung von UV-Spektren durch Differentiation 1. und 2. Ordnung im Rahmen der Kohlenwasserstoffanalyse

Fine Resolution of UV Spectra by Differentiation of 1st and 2nd Order in Hydrocarbon Analysis Basic UV spectra (0th order) in unpolar solvents such as cyclohexane are useful — though with some reservations — in characterizing mineral oils occuring in pure form and aromatic fractions in environmental samples separated by chromatographic techniques. The common standard raffinates, biogenic hydrocarbons or other mixes of hydrocarbons including polycyclic aromatics can be approximately identified. The spectra of 1st and 2nd order improve the reliability of the results and permit above all to detect polycondensated aromatics even in traces. Finally, partial spectra of 1st and 2nd order in the wavelength ranges 205…240, 220…260, and 260…320 nm allow because of their very specific structures a simple and fast practically definite assignment to the above-mentioned groups of aromatics. Analogously, substituted aromatics in detergents and other technical products have already been identified. The method is suitable as a fast preliminary test, at least.     

Use of the Comet assay to assess DNA damage in hemocytes and digestive gland cells of mussels and clams exposed to water contaminated with petroleum hydrocarbons

Oil spills can result in the deposition of large quantities of petroleum hydrocarbons into intertidal and shallow waters seriously impacting bivalve populations. Petroleum hydrocarbons are enriched in polycyclic aromatic hydrocarbons (PAH) and PAH analogs many of which may have potential to damage DNA. The Comet assay is useful for assessing DNA damage and has been used to a limited degree with aquatic organisms, but mostly with studies in vitro. We have carried out studies with the Comet assay to assess the DNA damaging potential of complex mixtures of petroleum hydrocarbons for bivalves. Experiments were carried out with mussels (Mytilus edulis) and clams (Mya arenaria) with dispersions and water soluble fractions of an Arabian crude oil which was also chemically characterized in detail by GC-MS. Pilot studies were first conducted to evaluate test performance and reproducibility. An interindividual coefficient of variation ranging from 17 to 30% was established for the assay with hemocytes and digestive gland cells of both species. Exposure to hydrocarbon fractions had no significant impact on clams. However, an increase in DNA damage was observed at P < 0.1 with digestive gland cells of mussels exposed to aqueous fractions of a light crude oil. These studies have demonstrated a potential for DNA damage in bivalves exposed to oil spills in inshore waters as well as potential for interspecies sensitivity.     

Bitumen biomarkers in the Mid-Proterozoic Ilímaussaq intrusion, Southwest Greenland - A challenge to the mantle gas theory

GC and GC/MS/MS analysis on rock extracts has shown that the bitumen in the peralkaline Ilímaussaq intrusion, previously assumed to be abiogenic, is biotic in origin. A biotic origin is in accordance with previously published stable carbon isotopic data on bituminous matter in the rocks. The biomarker distribution in the bitumen, including the less common bicadinanes, resembles that of oil seeps on the central West Greenland coast 2200 km farther north, whose source rocks and migration history are relatively well established. We use a recent re-construction of the subsidence and later exhumation of the West Greenland coastal region during the Mesozoic-Cenozoic (Japsen et al., 2006a, b) to anticipate that hydrocarbons migrated from deeper parts of the basin offshore west of Greenland. The rocks of Ilímaussaq were probably more deeply invaded than the surrounding granites due to their higher proportion of corroded minerals, which may explain why bitumen has not been observed elsewhere in the area.Hydrocarbon gases (C1-C5) present in fluid inclusions were also analysed, after having been released by treatment with hydrochloric acid that resulted in an almost complete disintegration of the Ilímaussaq intrusion rocks. The acid extraction method proved generally more efficient than the crushing procedure applied by others, but gave similar results for the chemical composition of the gas (CH₄: 88-97%) and isotopic ratios (δ¹³C₄CH: −1.6 to −5.0‰; δ¹³CC₂H₆: −9.2 to −12.5‰), with the exception of hydrocarbons hosted in quartz, which showed significantly lower isotopic values for methane (Graser et al., 2008). Previous researchers have suggested an abiotic origin for these hydrocarbon gases, but we suggest a biotic origin for the majority of them, not just those in quartz, assuming that the isotopic ratio of the constituents have changed due to loss of gas by diffusion. The assumption of gas loss via diffusion is supported by published studies on micro-fissures in minerals typical of the Ilímaussaq and field investigations showing diffusive loss of gas from the peralkaline Khibina and Lovozero massifs on the Kola Peninsula, Russia, which are, in many respects of mineralogy and hydrocarbon content, similar to the Ilímaussaq intrusion.Both the hydrocarbon gases and bitumen in the Khibina and Lovozero massifs have been cited as prime examples of a deep mantle source, although the carbon isotopic ratio of the bitumen clearly pointed to an organic origin. The trends in carbon isotopic ratio of methane released with time from freshly exposed rocks also supports our hypothesis of ¹³C enrichment of the methane remaining within the rock. Thus, there is good evidence that the hydrocarbons in the Kola alkaline massifs are mostly biotic in origin, in which case the probability of finding economic hydrocarbon accumulations from a deep mantle source seems exceedingly small.     

Variations in benthic fauna underneath an effluent mixing zone at a marine oil terminal in Port Valdez, Alaska

The distributions of hydrocarbons and infauna in sediments below a permitted mixing zone for the disposal of treated ballast waters in Port Valdez, Alaska were examined annually, 1999–2001. The associations of biological measures and the abundance of selected benthic organisms to total aromatic hydrocarbons (TARO) ranged up to large-sized effects, as compared against minimum-effect criteria (|r|0.63). The apparent sensitivity of three polychaete worms to low levels of hydrocarbons makes them particularly useful as indicators of future changes in spatial distributions of hydrocarbons associated with discharged effluent. In 2001, sediment TARO concentrations decreased and the correlation values of TARO to biotic variables were generally less than in 1999 and 2000. Evidence supports a conclusion of a strong but spatially limited association of some fauna with accumulations of petroleum hydrocarbons in these sediments.     

Hydrocarbon contamination in Cartagena Bay, Colombia

This study deals with the levels of aromatic and aliphatic hydrocarbon quantification in sediments and organisms in Cartagena Bay (Colombia), 1996-1997. Sediments (14 stations) and bivalves (2 stations) were monitored at different times of the year. Areas with high values were in the north with concentrations above 100 microg/g with a maximum of 1415 microg/g. Areas with low values were located toward the south, near the outlet of the Canal del Dique and Barú Island, with values below 10 microg/g. In other areas concentrations were between 50 and 100 microg/g. A decrease in sediment concentrations of hydrocarbons has occurred since 1983, but levels in some sectors are still similar to those in polluted areas. Organisms have relatively low values (8-30 microg/g for bivalves, and 10-40 microg/g for fish).