Oil-contaminated Seawater Research Articles

Adsorption Kinetics and Capacity of Fatty Acid-Modified Banana Trunk Fibers for Oil in Water

Oil spill leaves detrimental effects to environment, living organisms, and economy. As such, it is of considerable interest to find an effective, simple, and inexpensive method to treat this calamity. This work reports the use of banana trunk fibers (BTF) modified with oleic acid, stearic acid, castor oil, and palm oil for oil spill recovery. The maximum sorption capacity, effect of oil to water ratio, effect of light oil fractions, and effect of dissolved organic compounds in weathered oil-contaminated seawater were studied. It is found that BTF treated with oleic acid exhibited the best sorption capacity for engine oil, dissolved organic compounds in weathered oil, and light oil fractions. The equilibrium process was described well by the Freundlich isotherm model, and the kinetic studies show good correlation coefficients for a pseudo-second-order kinetic model.

Isolation of Crude Oil Degrading Marine Bacteria and Assessment for Biosurfactant Production

Ten bacterial isolates recovered from the crude oil contaminated sea water samples from a ship yard in Alang coast, Gujarat showed optimum growth in presence of crude oil. The crude oil degrading isolates were identified as species of genera Acinetobacter, Marinococcus, Micrococcus, Planococcus, Methylobacterium, Rhodococcus and Noccardia. All the ten isolates degraded 1% crude oil in Bushnell Haas broth. Highest biodegradation of crude oil was found to be 70% by the isolate M2 which belonged to genus Marinococcus. Other isolates showed biodegradation in the range of 55-30%. On addition of 1% Tween 80 biodegradation reduced in majority of cases. 70% of the bacterial isolates scored positive for biosurfactant production and emulsified toluene however emulsion stability varied drastically among the isolates. None of the biosurfactant producing bacterial isolates was hemolytic.

Analytical study on flow process of floating-oil recovery device from oil-contaminated seawater by MHD method

A new method of recovering maritime oil-spill based on electromagnetic force, the so-called MHD oil-spill recovery method was proposed in the IEECAS. The operating process of MHD channel was described in this article. Numerical study was carried out using a two-dimensional water-air two-phase model and the VOF method. The agreement between the numerical and the experimental results was reached.

Structural analysis of an extracellular polysaccharide produced by Rhodococcus rhodochrous strain S-2

A possibility has been suggested of applying the EPS produced by Rhodococcus rhodochrous strain S-2 (S-2 EPS) to the bioremediation of oil-contaminated environments, because its addition, together with minerals, to oil-contaminated seawater resulted in emulsification of the oil, increased the degradation of polyaromatic hydrocarbons (PAH) of the oil, and led to the dominance of PAH-degrading marine bacteria. To understand the underlying principles of these phenomena, we determined the chemical structure of the sugar chain of S-2 EPS. The EPS was found to be composed of d-galactose, d-mannose, d-glucose, and d-glucuronic acid, in a molar ratio of 1:1:1:1. In addition, 0.8% (w/w) of octadecanoic acid and 2.7% (w/w) of hexadecanoic acid were also contained in its structure. By 1H and 13C NMR spectroscopy, including 2D DQF-COSY, TOCSY, HMQC, HMBC, and NOESY experiments, as well as chemical and enzymatic analyses, the polysaccharide was shown to consist of tetrasaccharide repeating units with the following structure: [Display omitted]

Improvement in MHD Separation Device for Separation of Oil from Oil-Contaminated Seawater Using High-Field Superconducting Magnet

A unique device for separating oil from oil-contaminated seawater by the magnetohydrodynamics (MHID) method, so-called the MIID separation device, is improved on the basis of the results of observation of the inside of MHD separation cells. The MHID method is based on the difference in electric conductivity between seawater and oil; the separation force applied to oil as a reaction of the electromagnetic force is used for oil separation. The performance of the improved device with a mixture of artificial seawater and simulation particles instead of oil droplets is tested using a 10-T class superconducting magnet. The results show perfect separation at a magnetic field of 5 T 10.1 A or higher.

Trophic Interactions among Marine Microbes in Oil-contaminated Seawater on a Mesocosmic Scale

We studied the effects of oil spills on the trophic interactions among microorganisms in marine environments on a mesocosmic scale. When Bunker-A oil or kerosene was introduced into the mesocosm, bacterial numbers increased for the first 3 days, then decreased with a concomitant propagation of either heterotrophic nanoflagellates (HNFs) or viruses. We hypothesized that the sensitivity of HNFs to each oil resulted in this trophic relationship. To test this hypothesis, the rates at which HNFs grazed on bacteria were examined by conducting microcosm experiments in the presence of one of these oils. The rates were markedly reduced by kerosene but slightly increased by Bunker-A oil. The removal of HNFs by filtration led to a fluctuation in the numbers of bacteria and viruses that was quite similar to that in the mesocosm with kerosene. We conclude that the inhibitory effect of oil components on unicellular microorganisms is one of the key factors controlling the microbial food-web in oil-contaminated seawater.

Microbial communities in oil-contaminated seawater.

Although diverse bacteria capable of degrading petroleum hydrocarbons have been isolated and characterized, the vast majority of hydrocarbon-degrading bacteria, including anaerobes, could remain undiscovered, as a large fraction of bacteria inhabiting marine environments are uncultivable. Using culture-independent rRNA approaches, changes in the structure of microbial communities have been analyzed in marine environments contaminated by a real oil spill and in micro- or mesocosms that mimic such environments. Alcanivorax and Cycloclasticus of the gamma-Proteobacteria were identified as two key organisms with major roles in the degradation of petroleum hydrocarbons. Alcanivorax is responsible for alkane biodegradation, whereas Cycloclasticus degrades various aromatic hydrocarbons. This information will be useful to develop in situ bioremediation strategies for the clean-up of marine oil spills.

ＭＨＤ方式による海洋流出油の分離回収技術の基礎研究

ＭＨＤ方式による海洋流出油の分離回収技術の基礎研究

Bio-physicochemical treatment of oil contaminated sea water

This article introduces a combined physicochemical and biological process for treatment of oil contaminated sea water. In this process, a new polymeric surfactant is successfully applied with a dosage of 0.0015 g/g of crude oil to accumulate oil spots on the sea water in a microcosm. In the next step, microbial degradation of accumulated oil spots using isolated bacteria from oil contaminated Caspian Sea water was studied. The results of a proposed process for treatment of contaminated sea water in a pilot scale, using a 1500-l microcosm with several basins at different conditions are presented.

Influence of daylight on potential biodegradation of diesel and crude oil in Antarctic seawater

The effects of daylight exposure on Antarctic coastal bacterial communities contaminated by diesel fuel and ‘Arabian light’ crude oil addition were studied in artificial mesocosms during the austral summers of 1991–1992, 1992–1993 and 1993–1994 in the Terre Adelie land area. In order to study the possible influence of photo-oxidation, two sets of experiments were conducted in covered and noncovered batches. Daily sampling allowed regular surveys of the changes of total bacterial abundance, mean cell volumes, saprophytic and hydrocarbon-utilizing bacterial communities. The results clearly revealed a significant response of the Antarctic bacterial community to crude oil addition. Two orders of magnitude increases were observed after contamination. Concomitant enrichments of saprophytic and hydrocarbon-utilizing bacteria occurred during these periods. Hydrocarbon-utilizing bacteria ranged from 0.001% of the total community before contamination to more than 80% after 2 weeks of contamination with crude oil. Chemical analysis of the residual hydrocarbon fraction after 5 weeks of contamination confirmed this potential biodegradation. Solar radiation had no measurable effect upon crude oil-contaminated seawater. In contrast, there was a clear toxic effect upon bacterial communities contaminated with diesel. Data suggest that the initial state of the bacterial communities can play a major role in the potential biodegradation. Some surface bacterial assemblages seem to demonstrate a better resistance to solar radiation than deeper ones.

Effectiveness of bioremediation for oil-polluted Antarctic seawater

The effectiveness of a specific fertiliser (INIPOL EAP 22) addition on bioremediation of oil-contaminated Antarctic coastal seawater was determined in the “Terre Adelie” area. Mesocosm studies were conducted to evaluate the effects of “Arabian light” crude oil contamination on coastal bacterioplanktonic communities. After oil addition, regular surveys of the bacterial changes of the oil-contaminated seawater were performed during 5-week periods during the austral summer of 1992/1993 and 1993/1994. All results (total, saprophytic and hydrocarbon-utilising bacterial abundance) clearly revealed a significant response of Antarctic bacterial communities to hydrocarbon contamination. A 1 order of magnitude increase of bacterial microflora occurred in seawater after crude oil contamination. A concomitant enrichment in oil-degrading bacteria was generally observed, from less than 0.001% of the community in uncontaminated samples to up to 50% after 3 weeks of contamination. Addition of fertiliser (INIPOL EAP 22) induced clear enhancement of both saprophytic and hydrocarbon-utilising microflora. Chemical analysis of the residual hydrocarbon fractions confirmed that fertiliser application increased the rate of oil biodegradation.

Effect of dispersed oil on heterotrophic bacterial communities in cold marine waters

Mesocosm studies were conducted to evaluate the effect of dispersed oil on total and heterotrophic bacterial communities of under-ice seawater from the St. Lawrence Estuary. A regular survey of bacterial changes in the oil-contaminated seawater was performed during a two week period. The bacterial community structure was investigated by carrying out 27 morphological and biochemical tests on 168 isolated strains. The results show a detectable but transient response of the bacterial community to crude oil addition. While total bacterial counts were approximately constant during the experiment, dispersed oil induced an increase in heterotrophic bacterial microflora (from 10(4) to 10(5) bacteria ml(-1) after two weeks of contamination). The dispersed oil appeared to have an inhibitory effect on some components of the bacterial community. A decrease of most probable number values was observed just after addition of crude oil in the most polluted tanks and one day later in the less polluted tank. However, except for the most polluted tank, this adverse effect disappeared rapidly. While the dispersed oil induced a total disappearance of some components of the bacterial community in the most polluted tank, the structure of the bacterial community in the less polluted tank appeared relatively unchanged after 14 days of contamination.

Influence of oil shale on intertidal organisms: Sensory impairment in the blenny, Blennius pholis L. by oil shale extracts

As part of an investigation on the effect of natural oil seeps and oil-bearing substrata on littoral organisms, a study was made on the effect of the presence of freshly exposed Blackstone oil shale from Kimmeridge on the Dorset coast on the behaviour of the common littoral fish the blenny Blennius pholis L. in a simulated rock pool habitat. Plastic test chambers were designed with two compartments, one contained sea water and the other contaminated sea water which had been allowed to equilibrate with pieces of Blackstone oil shale and in some experiments further modified by decreasing the pH to simulate natural CO 2 build up in rock pools. The fish were allowed to enter the sea water in either compartment from one of three types of ramp positioned above the surface. The results showed that against appropriate controls, fish which are able to sample a saturated atmosphere avoid coming into contact with equilibrated shale oil-contaminated sea water. As the shale oil content decreased the aversion decreased but the oil still affected the ability of the fish to detect a decrease in pH. Apparently the presence of shale oil leachings in the sea water interferes with the ability of the blenny to discriminate certain characteristics of the physico-chemical environment which would otherwise be avoided.

Accumulation and release of petroleum-derived aromatic hydrocarbons by four species of marine animals

When exposed to oil-contaminated seawater, marine animals accumulate a wide variety of petroleum hydrocarbons in their tissues. Generally, the aromatic hydrocarbons are accumulated to a greater extent and are retained longer than the alkanes. In all species tested, accumulation of aromatic hydrocarbons appears to be dependent primarily on a partitioning of the hydrocarbons between the exposure water and the tissue lipids. Current evidence indicates that binding of hydrocarbons to tissue lipids is by hydrophobic interactions and not by covalent bonding. Bioaccumulation factors (tissue: water concentration ratio) increase in proportion to the increase in molecular weight of the aromatic hydrocarbons. When returned to oil-free seawater, marine animals rapidly release the accumulated hydrocarbons from their tissues. Release rates are species-dependent. Shrimp and fish, which can metabolize aromatic hydrocarbon, release them more rapidly than clams and oysters, which apparently lack the detoxifying enzymes. Release of hydrocarbons to background or undetectable levels requires from 2 to 60 days. The high molecular weight aromatic hydrocarbons are released more slowly than the low molecular weight hydrocarbons.