Hydrocarbons In Marine Sediments Research Articles

Petroleum Hydrocarbon Concentrations in Marine Sediments Along Chennai Coast, Bay of Bengal, India

The spatial and temporal distribution of petroleum hydrocarbons (PHC) in marine sediments along the Chennai coast, Bay of Bengal was quantified by Ultra-Violet Fluorescence (UVF) Spectroscopy. The concentration of PHC in surface sediments varied from 1.88 to 39.76ppm. The highest values obtained in the northern part of the study area, where shipping activities and land-based waste waters disposed into sea through the rivers like Kuvam and Adayar. The Adayar (7.26-16.83ppm) and Kuvam (5.5-39.72ppm) cores reveal a clear horizon of increase in PHC above 50 and 35cm respectively. PHC values showed a decreasing pattern with depth in all sediment cores suggesting the excess anthropogenic loading occurring in the recent past. The present study revealed that the PHC values of Chennai coastal sediments are lower than the values reported from selected costal areas including the sediment of the Mumbai coast (7.6-42.8ppm), Arabian Sea. The results will be useful for pollution monitoring program along the coastal region and also to check the level of petroleum hydrocarbons in marine sediments.

Distribution of polycyclic aromatic hydrocarbons in marine sediments and their potential toxic effects

The presence of polycyclic aromatic hydrocarbons (PAHs) in samples of marine sediments from Paranagua Bay on the southern coast of Brazil was investigated. Paranagua Bay is the location of a major port, one of the busiest in Brazil. The region has a great potential for tourism and port-related industries and activities. Due to its characteristics as a venue for tourism, two major campaigns were planned: one 3 months before the summer (between December and February) and a second after the vacation season. Total concentration of PAHs in sediments ranged from 26.33 to 406.76 ng/g (in both campaigns). The highest values were found in sediments with higher organic carbon content. We found no substantial differences between the two campaigns, and the values are quite similar. Ternary diagrams show that points P5 and P6 were considered polluted, while others were classified as non-polluted. Molecular ratios indicate that the main sources of PAHs are petrogenic and the burning of fossil fuels. Sediment toxicity was assessed by the presence of PAHs in terms of benzo(a)pyrene (BaP) concentration. The toxicity of PAHs mixtures can be characterized more accurately by developing and establishing toxic equivalency factors (TEFs) for PAHs. Considering TEFs, the BaP(eq) concentrations vary between 0.264 and 5.922 ng/g (considering both campaigns). Thus, two points are above the maximum level recommended (3 ng/g) by the Netherlands sediment quality guidelines. In fact, sites P5 and P6 apparently are exposed to a greater number of pollution sources, thus reflecting the higher concentration of PAHs compounds in sediments.

Development of methods to collect and analyze gasoline range (C5–C12) hydrocarbons from seabed sediments as indicators of subsurface hydrocarbon generation and entrapment

Abstract Gasoline range hydrocarbons (C 5 –C 12 ) are usually associated with petroleum generation, yet few surface geochemical surveys have attempted to evaluate the gasoline range hydrocarbons in near-surface marine sediments. This is due to the difficulty in capturing and analyzing this volatile range of hydrocarbons with minimum loss and evaporative fractionation. In this study, a Headspace Solid Phase Microextraction (HSPME) method was developed and evaluated for the purpose of capturing the gasoline range of hydrocarbons within unconsolidated sediment using a solventless protocol. The sediment SPME extraction method is based on the condition that phase/composition equilibrium is reached between sediment/water mix, container headspace, and SPME fiber coated with sorbent. In the experiments, the effectiveness of SPME to detect and measure low concentrations of migrated crude oil in marine sediments was evaluated. The following optimum laboratory procedure for SPME gasoline monitoring was established: collect the sample in sealed disrupter chamber (sealed sediment storage container which breaks apart sediment and releases interstitial volatile hydrocarbons), use a water bath to keep a stable laboratory temperature, use an NaCl saturated solution to help aromatic compounds move out of the solution to vapor phase, and wait a sufficient time to reach equilibrium. The results show that HSPME is very sensitive with sub ppm detection limits. SPME proved to be suitable to reveal the natural background and micro-seepage level of gasoline hydrocarbons in marine sediments.

Development of a focused ultrasonic-assisted extraction of polycyclic aromatic hydrocarbons in marine sediment and mussel samples

Focused ultrasonic-assisted extraction (FUSE) is a new and particular technique based on the cavitation effect. In this work, the focused ultrasound assisted extraction was studied and developed for the extraction of polycyclic aromatic hydrocarbons from marine sediments and mussel tissues. The variables influencing the extraction (amplitude of the ultrasound pulse, the extraction time and the solvent) were studied by a full factorial design and a central composite design. As a result, flat response surfaces were obtained and the most convenient conditions were 45% of ultrasound amplitude, 120 s of extraction time and 5 mL of acetone. Both accuracy and precision of the method were evaluated by means of two certified reference materials (marine sediment and mussel tissue) and the results were also compared to those obtained by microwave assisted extraction.

Levels and toxicity of polycyclic aromatic hydrocarbons in marine sediments

The occurrence of polycyclic aromatic hydrocarbons (PAHs) in the marine environment has attracted the attention of the scientific community, as these compounds are frequently detected in seawater and sediments at increasing levels and can have adverse health effects on marine organisms and humans. Several PAHs are potential human carcinogens and are included in the priority list of the European Union’s Water Framework Directive (2000/60/EC). Research regarding their environmental levels requires their determination by gas-chromatography and liquid-chromatography techniques, which have been developed and optimized, especially for marine-sediment samples. Results of sample analyses reveal the increasing occurrence of many species of PAHs worldwide, especially in marine sediments, where they finally accumulate, mostly in areas near intense industrial activities. In parallel, research on the toxicity of PAHs and their mixtures is continuing and is aiming to provide more insight into the health risks associated with the levels of PAHs in the environment.

The usefulness of total concentrations and pore water concentrations of pesticides in soil as metrics for the assessment of ecotoxicological effects ‐ Scientific Opinion of the Panel on Plant Protection Products and their Residues (PPR)

The usefulness of total concentrations and pore water concentrations of pesticides in soil as metrics for the assessment of ecotoxicological effects ‐ Scientific Opinion of the Panel on Plant Protection Products and their Residues (PPR)

Laboratory methods for evaluating migrated high molecular weight hydrocarbons in marine sediments at naturally occurring oil seeps

A laboratory study has been conducted to determine the best methods for the detection of C 10–C 40 hydrocarbons at naturally occurring oil seeps in marine sediments. The results indicate that a commercially available method using n-C 6 to extract sediments and gas chromatography–flame ionization detection (GC–FID) to screen the resulting extract is effective at recognizing the presence of migrated hydrocarbons at concentrations from 50 to 5000 ppm. When non-biodegraded, the amount of oil charge is effectively tracked by the sum of n-alkanes in the gas chromatogram. However, once the charge oil becomes biodegraded, with the loss of n-alkanes and isoprenoids, the amount of oil is tracked by the quantification of the unresolved complex mixture (UCM). Gas chromatography–mass spectrometry (GC–MS) was also found to be very effective for the recognition of petroleum related hydrocarbons and results indicate that GC–MS would be a very effective tool for screening samples at concentrations below 50 ppm oil charge.

Analysis of light hydrocarbons in marine sediments by headspace technique: Optimization using design of experiments

Headspace technique is a common method to analyze light hydrocarbons in deep marine sediments. The use of an automatic headspace sampler instead of a manual injection is the guarantee for a better repeatability and furthermore it is less time consuming. But to increase the sensitivity and therefore, to achieve a better detection limit, it is necessary to optimize the automatic headspace sampler parameters. The theory of design of experiments was applied here by studying them. As a response, methane, which is an important gas in marine sediments, was chosen for its short analysis time. Regarding the parameters for automatic headspace sampler, eight variables were selected and then, a screening of them was carried out with a fractional factorial design to determine the influential factors. Finally, optimization was conducted with four factors: Sample Loop Fill time ( t slf), Oven temperature ( T° o), Vial Pressurization time ( t vp) and Vial pressure ( P v). They were modeled with a Doehlert experimental design. Then, the model was validated by a conventional statistical test (analysis of variance) and the optimum has been found and checked by three experiments. Results on light hydrocarbons measured in sediments from the Congo–Angola Basin are given, as an example.

Chronic toxicity of unresolved complex mixtures (UCM) of hydrocarbons in marine sediments

Background, Aim and Scope Unresolved complex mixtures (UCM) of hydrocarbons, containing many thousands of compounds which cannot be resolved by conventional gas chromatography (GC), are common contaminants of sediments but little is known of their potential to affect sediment-dwelling organisms. Evidence exists for reduced health status in mussels, arising from aqueous exposure to aromatic UCM components acting through a narcotic mode of action. However, UCM contaminants in sediments may not be sufficiently bioavailable to elicit toxic effects. The aim of our study was therefore to measure the sublethal effects of chronic exposure to model UCM-dominated oils at environmentally realistic concentrations and compare this to effects produced by a UCM containing weathered crude oil. A further aim was to determine which, if any, fractions of the oils were responsible for any observed toxicity.

Effects of dose and particle size on activated carbon treatment to sequester polychlorinated biphenyls and polycyclic aromatic hydrocarbons in marine sediments

Recent laboratory studies show that mixing activated carbon with contaminated sediment reduces the chemical and biological availability of hydrophobic organic contaminants. In this study, we test the effects of varying the activated carbon dose and particle size in reducing the aqueous availability of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) and the uptake of PCBs by two benthic organisms. We mixed PCB- and PAH-contaminated sediment from Hunters Point Naval Shipyard, San Francisco Bay (CA, USA), for one month with activated carbon, at doses of 0.34, 1.7, and 3.4% dry mass basis. We found that increasing the carbon dose increased the effectiveness in reducing PCB bioaccumulation. In 56-d uptake tests with the benthic organisms Neanthes arenaceodentata and Leptocheirus plumulosus, PCB bioaccumulation was reduced by 93 and 90%, respectively, with 3.4% carbon. Increasing the dose also increased the effectiveness in reducing PCB and PAH aqueous concentrations and uptake by semipermeable membrane devices and quiescent flux of PCBs to overlying water. Decreasing activated carbon particle size increased treatment effectiveness in reducing PCB aqueous concentration, and larger-sized activated carbon (400-1,700 microm) was ineffective with a contact period of one month. We invoke a numerical model based on intraparticle diffusion in sediment and activated carbon particles to help interpret our experimental results. This model was useful in explaining the trends for the effect of activated carbon dose and particle size on PCB aqueous concentrations in well-mixed systems.

Evaluation of atmospheric transport as a nonpoint source of polycyclic aromatic hydrocarbons in marine sediments of the Eastern Mediterranean

Coastal marine sediment, air and seawater samples were collected at six sampling stations in the Eastern Mediterranean Sea distant from pollutant point sources. All sediment samples were analyzed to determine polycyclic aromatic hydrocarbon (PAH), black carbon (BC) and organic carbon (OC) contents. The PAH contents of gaseous and seawater samples of the study were determined in order to evaluate the role of air–sea exchange as PAH nonpoint source to the marine sediments. The average concentration of the total PAHs (∑PAHs) in the sediments varied from 2.2 to 1056.2 ng g −1 dry weight. The average BC and OC contents varied from 0.3 to 5.6 and from 2.9 to 21.4 mg g −1 dry weight, respectively. ∑PAH concentration in the marine atmosphere varied from 20.0 to 83.2 ng m −3. Air–water exchange flux ( F A–W) estimation has indicated air transport as a significant source of PAHs to pristine marine sediments of Eastern Mediterranean. In addition, the significant correlation between the PAHs and the organic and soot carbon content further suggests the importance of atmospheric input of PAHs to the sediments.

Improved Accuracy of GC-MS Quantification of Aliphatic and Aromatic Hydrocarbons in Marine Sediments and Petroleums. Validation on Reference Matrices and Application to the Erika Oil Spill

A rapid and simple analytical procedure allowing accurate quantification of aliphatic and aromatic hydrocarbons in sediments and petroleum has been developed. Sediments were Soxhlet extracted using methylene chloride for 48 h. Oil maltene fractions were isolated by asphaltene precipitation in pentane. Sediment and oil extracts were first purified using alumina micro-columns. Saturated fractions were then separated from aromatic ones by fractionation on silica gel. Alkanes and polycyclic aromatic hydrocarbons (PAHs) were analyzed separately by gas chromatography coupled to mass spectrometry (GC-MS). PAHs and alkanes were quantified relative to perdeuterated PAHs and alkanes introduced prior to extraction. For accurate quantification, it is important to use several perdeuterated alkanes that cover the volatility range of alkanes of interest and at least one perdeuterated PAH per class of aromaticity. This analytical procedure has been validated on a reference material sediment (SRM 1941a) and a reference material crude oil (SRM 1582). This analytical procedure was then applied to the study of the contamination of marine sediments collected along the Atlantic coast after the Erika oil spill (December 1999).

Cloud-point preconcentration and HPLC determination of polycyclic aromatic hydrocarbons in marine sediments

Cloud-point methodology has been used to develop a new procedure for preconcentration of polycyclic aromatic hydrocarbons previously extracted from marine sediment with a micellar polyoxyethylene-10-lauryl ether medium by microwave- or ultrasound-assisted extraction. The optimum conditions for preconcentration and determination of PAH by HPLC with UV detection were established. The optimized procedure was applied to determination of these analytes in fortified marine sediment. The mean recoveries obtained after extraction and preconcentration by use of microwave- or ultrasound-assisted extraction were 105.8 and 99.5%, respectively. Precision, however, is considerably higher when extraction is performed ultrasonically.

Comment on “PAH refractory index as a source discriminant of hydrocarbon input from crude oil and coal in Prince William Sound, Alaska” by F.D. Hostettler, R.J. Rosenbauer, K.A. Kvenvolden

This comment addresses the recent paper by Hostettler et al. proposing a new geochemical refractory PAH index, T/C (the ratio of triaromatic steranes to methyl chrysenes), and using the index to indicate that coal is the main source of the natural petrogenic hydrocarbons in marine sediments in Prince William Sound, Alaska. In response Bench et al. argue that coal is only one of several possibilities, and that measurements of vitrinite/kerogen reflectance, hydrocarbon mass balance calculations, and other molecular indicators including biomarkers demonstrate that coal is not the dominant source. The small sample of data used by Hostettler et al., evidence from vitrinite/kerogen reflectance data, beach coal, mass balance constraints, and the limitations of the T/C index are discussed. Selected molecular parameters in the sediments and in the potential sources of the hydrocarbons background are tabulated.

Determination of polycyclic aromatic hydrocarbons in marine sediments using a new ASE-SFE extraction technique.

In order to determine PAHs in marine sediment samples by GC/MS(SIM) a new extraction approach of ASE-SFE was evaluated using combined accelerated solvent extraction (ASE, dynamic and static mode) and supercritical fluid extraction (SFE, dynamic mode) without further purification of the sample. The solvents used for ASE-SFE were methylene chloride and carbon dioxide. The recovery data, precision and accuracy of the whole method were evaluated statistically. The average recoveries of PAHs, based on deuterated internal standards were 77% for 2-3-ring PAHs, 85% for 4-ring PAHs, 88% for 5-ring PAHs and 97% for 6-ring PAHs. The extraction time required for the ASE-SFE technique was 30 min, which is longer than in the case of independent use of ASE and shorter compared to SFE. ASE-SFE recoveries of PAHs from SRM marine sediment are comparable for (2-3-ring, 4-ring PAHs) or higher (5-ring, 6-ring PAHs) than reported for the conventional extraction methods of ASE and SFE. Method detection limits of (MDL) were statistically estimated. MDL values obtained for 15 PAHs compounds vary between 0.06 ngg(-1) and 3.54 ngg(-1).

Determination of polycyclic aromatic hydrocarbons in marine sediments by high-performance liquid chromatography after microwave-assisted extraction with micellar media

A simple and rapid method is developed for extraction and determination of polycyclic aromatic hydrocarbons (PAHs) in marine sediments. The procedure was based on the microwave-assisted extraction of PAHs in marine sediment samples using a micellar medium of Polyoxyethylene 10 lauryl ether as extractant. Two-level factorial designs have been used to optimize the microwave extraction process. The analysis of extracts has been carried out by HPLC with UV detection. Fortified sediments gave an average recovery between 85.70 and 100.73%, with a relative standard deviation of 1.77–7.0% for PAHs with a ring number higher than three.

Optimization of microwave-assisted extraction of hydrocarbons in marine sediments: comparison with the Soxhlet extraction method

Microwave energy was applied to extract polycyclic aromatic hydrocarbons (PAHs) and linear aliphatic hydrocarbons (LAHs) from marine sediments. The influence of experimental conditions, such as different extracting solvents and mixtures, microwave power, irradiation time and number of samples extracted per run has been tested using real marine sediment samples; volume of the solvent, sample quantity and matrix effects were also evaluated. The yield of extracted compounds obtained by microwave irradiation was compared with that obtained using the traditional Soxhlet extraction. The best results were achieved with a mixture of acetone and hexane (1:1), and recoveries ranged from 92 to 106%. The extraction time is dependent on the irradiation power and the number of samples extracted per run, so when the irradiation power was set to 500 W, the extraction times varied from 6 min for 1 sample to 18 min for 8 samples. Analytical determinations were carried out by high-performance liquid chromatography (HPLC) with an ultraviolet-visible photodiode-array detector for PAHs and gas chromatography (GC) using a FID detector for LAHs. To test the accuracy of the microwave-assisted extraction (MAE) technique, optimized methodology was applied to the analysis of standard reference material (SRM 1941), obtaining acceptable results.

Normalization of Sedimentary Lipid Biomarker Concentrations to Total Organic Carbon in Principal Component Analysis

The objective of this study is to demonstrate the importance of normalizing lipid biomarker concentrations in sediment to total organic carbon (TOC) for principal component analysis (PCA) by using n-alkanols and aliphatic hydrocarbons in marine sediments collected from the East China Sea shelf off northern Taiwan. In performing PCA, logarithmically transformed data and z-score function transformed data along with the raw data were compared with TOC normalized data. Results show that the positions of n-alkanol variables in the loading plot using TOC normalized data are in good agreement with the organic geochemical knowledge in terms of sources. For aliphatic hydrocarbons, the positions of samples in the score plot using TOC normalized data are different from those using the raw data and z-score function transformed data. It is suggested that normalization of lipid biomarker concentrations with TOC be taken into consideration in performing PCA when the grain size distributions of sediments in a study area vary in a wide range.

Chlorinated hydrocarbons in marine sediments of the Baja California (Mexico)-California (USA) border zone

Chlorinated hydrocarbons in marine sediments of the Baja California (Mexico)-California (USA) border zone

Chlorinated Hydrocarbons in Marine Sediments of the Baja California (Mexico)--California (USA) Border Zone

Chlorinated Hydrocarbons in Marine Sediments of the Baja California (Mexico)--California (USA) Border Zone