The effect of crude oil and oil spill chemicals on nitrogen fixation in the cyanobacteria Nostoc sp

The effects of crude oil and three oil spill dispersants (Corexit 9600, 9550 and 7664) on nitrogenase activity in the cyanobacteria Nostoc sp. were examined. The addition of oil to Nostoc sp. cultures resulted in a catastrophic decline in nitrogenase activity with activity ceasing 7 h after treatment. The addition of a dispersant with the oil did not ameliorate this effect. Cultures exposed to high concentrations of dispersants showed lower rates on nitrogenase activity than untreated cultures. However, it is unlikely that dispersant concentrations of this magnitude would occur in the field. At the lowest concentration tested, which approximates the manufacturer's recommended application rate, the effects of the dispersant appear to be negligible.     

Crude oil contaminated soil washing in air sparging assisted stirred tank reactor using biosurfactants

This study investigated the removal of crude oil from soil using air sparging assisted stirred tank reactors. Two surfactants (rhamnolipid and sodium dodecyl sulfate, SDS) were tested and the effects of different parameters (i.e. temperature, surfactant concentrations, washing time, volume/mass ratio) were investigated under varying washing modes namely, stirring only, air sparging only and the combination of stirring and air sparging. The results showed that SDS removed more than 80% crude oil from non-weathered soil samples, whilst rhamnolipid showed similar oil removal at the third and fourth levels of the parameters tested. The oil removal ability of the seawater prepared solutions were better than those of the distilled water solutions at the first and second levels of temperature and concentration of surfactant solutions. This approach of soil washing was noted to be effective in reducing the amount of oil in soil. Therefore we suggested that a field scale test be conducted to assess the efficiency of these surfactants.     

Evaluation of biosurfactants for crude oil contaminated soil washing

An evaluation of the ability of aqueous biosurfactant solutions (aescin, lecithin, rhamnolipid, saponin and tannin) for possible applications in washing crude oil contaminated soil was carried out. The biosurfactants behaviour in soil-water, water-oil and oil-soil systems (such as foaming, solubilization, sorption to soil, emulsification, surface and interfacial tension) was measured and compared with a well-known chemical surfactant (sodium dodecyl sulphate, SDS) at varying concentrations. Results showed that the biosurfactants were able to remove significant amount of crude oil from the contaminated soil at different solution concentrations for instance rhamnolipid and SDS removed up to 80% oil and lecithin about 42%. The performance of water alone in crude oil removal was equally as good as those of the other biosurfactants. Oil removal was due to mobilization, caused by the reduction of surface and interfacial tensions. Solubilization and emulsification effects in oil removal were negligible due to the low crude oil solubilization of 0.11%. Therefore, these studies suggest that knowledge of surfactants' behaviour across different systems is paramount before their use in the practical application of oil removal.     

Impact of dispersed fuel oil on cardiac mitochondrial function in polar cod Boreogadus saida

In this study, impact of dispersed oil on cardiac mitochondrial function was assessed in a key species of Arctic marine ecosystem, the polar cod Boreogadus saida. Mature polar cod were exposed during 48 h to dispersed oil (mechanically and chemically) and dispersants alone. The increase observed in ethoxyresorufin-O-deethylase activity and polycyclic aromatic hydrocarbon metabolites in bile indicated no difference in contamination level between fish exposed to chemical or mechanical dispersion of oil. Oil induced alterations of O₂ consumption of permeabilised cardiac fibres showing inhibitions of complexes I and IV of the respiratory chain. Oil did not induce any modification of mitochondrial proton leak. Dispersants did not induce alteration of mitochondrial activity and did not increase oil toxicity. These data suggest that oil exposure may limit the fitness of polar cod and consequently could lead to major disruption in the energy flow of polar ecosystem.     

Analysis of stability of silica nano-particle-laden microbubble dispersion

Microbubbles are small gas-filled bubbles which have wide application in various industries. The stability of microbubble is of primary concern for the application of microbubble. In this research, the stability of microbubble dispersion generated using CTAB surfactant is analyzed by drainage mechanism. The stability of microbubble dispersion is studied on the basis of the half-life of microbubble dispersion. Microbubble dispersion gas fraction and apparent rise velocity of interface of microbubble dispersion are also calculated. The size of microbubble is estimated from the apparent rise velocity of interface of microbubble dispersion. Further, silica nano-particles are added to the surfactants to study their effect on the stability of microbubble dispersion. The observed results clearly indicate that the stability of microbubble dispersion is significantly affected by the surfactant concentration and the weight of silica nano-particle in the liquid. Similar results were observed for the apparent rise velocity of interface and bubble size of dispersion. The present work may be beneficial for the application of microbubble in various chemical and biochemical industries and scientific community.

     

Review article: effects of oil pollution, chemically treated oil, and cleaning on thermal balance of birds

The acute effect of oil pollution on birds is on their thermal balance. Oil adheres to the plumage and causes a reduction in water repellant properties of the plumage, causing water to penetrate into the plumage to displace the insulating layer of air. The effect of oil on the plumage insulation is dose-dependent. The effect of oiling is greatly enhanced when the oil is spread in the plumage due to preening. In water, plumage oiling may cause the heat loss to exceed the bird's heat production capacity, resulting in hypothermia. If the oiled bird is ashore, with a dry plumage, it may have a normal thermal insulation. Bird species dependent upon feeding in water (such as diving birds) are therefore much more susceptible to the harmful effects of oil pollution than are semi-aquatic species that can feed ashore. It is possible to restore the water-repelling and insulative properties of the plumage by the process of cleaning if all the oil and soap is removed, and if the plumage is completely dry. Chemical treatment of oil has been suggested as a way to reduce the impact of oil spills on avian life. However, very few reports seem to have addressed the effects of chemically treated oil on the thermal balance of birds, and the results from one study actually indicate that oil treated with dispersants may be more harmful to birds than oil. The urgent need for more information about the effects of chemically treated oil on aquatic birds is therefore stressed.     

Efficiency of recycled wool-based nonwoven material for the removal of oils from water

The aim of this study was to highlight the potential use of recycled wool-based nonwoven material for the removal of diesel fuel, crude, base, vegetable and motor oil from water. Sorption capacity of the material in water and in oil without water, oil retention, sorbent reusability and buoyancy in static and dynamic conditions were investigated. The results show high sorption capacity of recycled wool for different kinds of oil. This sorbent also exhibited excellent buoyancy after 24h of sorption as well as a good reusability since the decrease in sorption capacity did not exceed 50% of the initial value after five sorption cycles in oil without water.     

TiO2 photocatalytic degradation of PCBs in soil-water systems containing fluoro surfactant

Titanium dioxide-mediated photodegradation of Polychlorinated biphenyls (PCBs) in soil/aqueous systems with added fluorinated surfactant was investigated. PCBs can bind tightly to organic matter in the soil, especially in aged, contaminated soil. Experiments showed an effective PCB photocatalytic degradation in mixed systems of soil/clay with anionic fluorinated surfactant FC-143 and TiO2. The FC-143 surfactant is stable in this photochemical process. PCB degradation rates in samples followed the order: spiked clay > spiked soil > Hudson River bank soil. The results suggest that anionic fluorinated surfactant may form semimicelles and/or admicelles on the surface of positively charged TiO2. The hydrophobic surface of TiO2 can provide a nonpolar phase that acts as a partioning medium for hydrophobic PCBs. Therefore, PCBs in soil can be released to the semimicelle and/or admicelle on the TiO2 surface and are effectively photodegraded in a dispersion containing anionic fluorinated surfactant. The combination of surfactant extraction and photooxidation forms the basis for a novel two-stage process for the removal and destruction of PCBs from soil.     

Compositional Changes of Aromatic Steroid Hydrocarbons in Naturally Weathered Oil Residues in the Egyptian Western Desert

Naturally weathered oil residues from an arid dumpsite in Al-Alamein, Egypt were analyzed for monoaromatic and triaromatic steranes to demonstrate the utility of biomarker compounds in assessing the chemical composition changes during the degradation of the released oil residues in a terrestrial environment. The characterizations of individual aromatic compounds were based on gas chromatography/mass spectrometry (GC/MS) analyses. The results showed that triaromatic sterane distributions were similar in the oil residues of varying weathering degradation extents and correlated with a fresh crude oil sample of the Western Desert-sourced oil. Molecular ratios of triaromatic sterane compounds (ratios of C 28 20R /C 28 20S , C 27 20R /C 28 20R , and C 28 20S /[C 26 20R + C 27 20S ]) were proved to be suitable for source identification. Major changes in chemical compositions during weathering of the oil residues were the depletion of short chain mono- and tri-aromatic steranes in samples that had undergone extensive degradation. The results of triaromatic sterane distribution are in good agreement with weathering classification based on the analyses of saturate and aromatic hydrocarbons and the ratios of n -alkanes, PAHs and saturate biomarker compounds.     

Immiscible fluid flow in porous media: dielectric properties

The movement and retention of immiscible fluids in porous media was determined using a microwave dielectric measuring technique. The technique was used to monitor the composite dielectric constant of columns containing model soil materials to observe the effect of displacement of various saturating fluids by water and determine the retained immiscible components. Various combinations of displacing fluids, both miscible and immiscible, were studied, yielding time-dependent flow characteristics as well as the total retention factor. The flow circumstances were similar to what would be encountered in an accidental spill of chlorocarbons or crude oil.The retention of chlorocarbons and crude oil was determined for model soils consisting of sand or glass spheres. The storage capacity of the sand for immiscible fluids was dependent on the fluid initially saturating the porous medium. For chlorocarbons, it was increased in water-wet compared to dry sands while the inverse was true for crude oil. The retention of crude oil in the sand was dependent on the water flow velocity and was much larger than that for chlorocarbons. The crude oil could be displaced by solvents such as cyclohexane in the sand but the net volume occupied by the two immiscible fluids after water flushing did not change appreciably, i.e. the crude oil component was replaced by the solvent. Application of a miscible fluid-water mixture or surfactants improved the ability of water to displace the immiscible fluid from the sand column.     

A protocol for assessing the effectiveness of oil spill dispersants in stimulating the biodegradation of oil

Dispersants are important tools in oil spill response. Taking advantage of the energy in even small waves, they disperse floating oil slicks into tiny droplets (<70 μm) that entrain in the water column and drift apart so that they do not re-agglomerate to re-form a floating slick. The dramatically increased surface area allows microbial access to much more of the oil, and diffusion and dilution lead to oil concentrations where natural background levels of biologically available oxygen, nitrogen, and phosphorus are sufficient for microbial growth and oil consumption. Dispersants are only used on substantial spills in relatively deep water (usually >10 m), conditions that are impossible to replicate in the laboratory. To date, laboratory experiments aimed at following the biodegradation of dispersed oil usually show only minimal stimulation of the rate of biodegradation, but principally because the oil in these experiments disperses fairly effectively without dispersant. What is needed is a test protocol that allows comparison between an untreated slick that remains on the water surface during the entire biodegradation study and dispersant-treated oil that remains in the water column as small dispersed oil droplets. We show here that when this is accomplished, the rate of biodegradation is dramatically stimulated by an effective dispersant, Corexit 9500®. Further development of this approach might result in a useful tool for comparing the full benefits of different dispersants.     

Study on the effect of temperature and pressure on nickel-electroplating characteristics in supercritical CO2

In this work, it was investigated the effect of solubility in supercritical CO2 on the nickel-electroplating characteristics. The plating characteristics could be controlled by electric resistance and dispersion in emulsion as well. CO2 concentration had better be controlled at lower concentration than 50 CO2 wt% to decrease electric resistance since supercritical CO2 is non-polar material. Non-ionic surfactant with EO/PO block copolymer was more efficient than any other surfactant and the dispersion at 0.2 surfactant wt% was better than at any surfactant concentration and over-added surfactant concentration over 0.2 wt% brought to the decrease of dispersion properties. Electric resistance was constant at 20Omega in ranging from pH 2.2 to pH 3.5 and increased slowly to 50Omega at pH 4 and rapidly to 400Omega at pH 5. Characteristics of nickel film has a close relation with solubility in supercritical CO2 and solubility is dependent on pressure and temperature. Solubility at 16 MPa was higher than that any other at pressure and at constant pressure of 16 MPa, solubility in supercritical CO2 increased with an increasing temperature from 31 to 45 degrees C and decreased over 45 degrees C.     

Optimization and treatment of wastewater of crude oil desalting unit and prediction of scale formation

In this article, one of Iran’s southwest oil fields that produces 3200 barrels per day (bbl/d) of wastewater from oil and gas processing was investigated. Experimental analysis of oil reservoir water and desalting wastewater disposal of crude oil desalting unit was performed. First, water was treated with a reverse osmosis membrane. As a result, the purified water, with lower total dissolved solids (TDS) and pH, was a suitable candidate for injection into the adjacent wells of the crude oil desalting unit. The effectiveness and compatibility of this wastewater to the formation water of the oil field wells were simulated. Finally, we studied and identified the formation, the amount, and the type of mineral scale deposits. These are the most important problems during water injection into the wells. The analysis shows that the refined water from the reverse osmosis (RO) process was a suitable and low-cost economical option for injection in onshore and offshore fields, due to the low amount of salts, the concentration of susceptible ions in scaling formation, and the appropriate pH. This oil field, which is in the second half of life, requires enhanced oil recovery methods (EOR) for the maintenance of pressure and an increase in oil recovery.

     

Polycyclic aromatic hydrocarbons in crude oil-contaminated soil: A two-step method for the isolation and characterization of PAHs

A two-step analytical method is developed for the isolation and characterization of polycyclic aromatic hydrocarbons (PAHs) in crude oil contaminated soil. In the first step, those crude oil components were isolated which are easily mobilized with water from the contaminated soil (determination of groundwater pollution potential). In the second step, the fraction containing the remaining crude oil compounds was extracted using toluene. After the cleanup of the fractions, both fractions were analyzed using high-performance liquid chromatography (HPLC). The HPLC of the toluene extracted fraction shows that along with the sixteen priority pollutants from the US-EPA list, many other polycyclic aromatic hydrocarbons (PAHs) are present as well. It is evident from the chromatograms that a significant amount of PAHs are present as is also the case in the fractions eluted by water. The described method allows the determination of total organic pollutants from crude oil, some of them being potential groundwater contaminants. The major part of the total pollutants could not be mobilized by water and therefore remains in the soil, which was extracted in the second step.     

The effects of crude and fuel oils on the growth, chlorophyll 'a' content and dry matter production of a green alga Scenedesmus quadricauda (Turp.) bréb

The growth of Scenedesmus quadricauda algae in a batch culture was examined in the presence of crude oil and fuel oil, added to the cultivation medium in the form of a water-soluble fraction (WSF), water extract (WE) and oil-water dispersion (OWD). On applying various concentrations of oils, a decrease in the number of cells, dry matter and chlorophyll 'a' production, with respect to the cell population, was observed. The extent of this decrease depended on the kind and concentration of the soluble and dispersed hydrocarbon fractions and on the proportions in which these occurred in the culture medium. On the other hand, the water extracts of both oils stimulated dry mass and chlorophyll 'a' content with respect to a single cell. This effect was accompanied by increased size of the algal cells. The WSF, WE and OWD of fuel oil, prepared from 200, 50 and 1 cm(3) of oil per dm(3) of BBM medium, respectively, had a similar inhibitory effect, which points to the dominant role of oil dispersion in the reduction of algal growth. Chemical analysis of the water extracts of fuel oil revealed the presence of 35 hydrocarbons of various kinds, mainly n-alkanes and polycyclic aromatic hydrocarbons.     

Organic matrix in produced water from the Osage-Skiatook petroleum environmental research site, Osage county, Oklahoma

Produced water (water co-produced with oil and gas) constitutes the single largest waste stream for oil and gas industry. Reclaiming this water for beneficial use is thought to be one of the most practical solutions that can solve both environmental and water shortage problems. The feasibility of this practice depends on the ability to remove its chemical content to the levels that meets the appropriate standards. Organic compounds are probably the most difficult fraction to handle. In this paper, the discrete organic compounds and non-volatile, macromolecular organic compounds (i.e., natural organic matter--NOM) of three produced water samples from the Osage-Skiatook Environmental Research site were characterized. Two of the three produced waters had very little contribution from NOM, while one of the samples had about 23% NOM contribution to its organic matrix pool. Fluorescent spectrophotometric scans provided little differentiation among the organic quality of the produced water, while pyrolysis-GC/MS showed that the NOM characteristics of the three produced waters were distinct. Specifically, the overall halogenated content and aromaticity of the NOM were found to be possible qualifiers that distinguish produced water from the coalbed methane well from produced water from the oil well. And the specific chemical fragments that are linked to polysaccharide sources were found to be potential identifiers that distinguish produced water from the newer oil well from produced water from the older oil well. These identifiers were, however, only suggested for this preliminary study. More samples must be included to build a substantial database on produced water NOM to confirm and identify more markers.     

Evaluation of bioremediation effectiveness on crude oil-contaminated sand

A treatability study was conducted using sea sand spiked with 3% or 6% (w/w) of Arabian light crude oil to determine the most effective bioremediation strategies for different levels of contamination. The sea sand used in the study was composed of gravel (0.1%), sand (89.0%), and silt and clay (10.9%). The water content of the sea sand was adjusted to 12.6% (w/w) for the study. Different combinations of the following treatments were applied to the sand in biometer flasks: the concentration of oil (3% or 6%), the concentration of a mixture of three oil-degrading microorganisms (Corynebacterium sp. IC-10, Sphingomonas sp. KH3-2 and Yarrowia sp. 180, 1x10(6) or 1x10(8) cells g-1 sand), the concentration of the surfactant Tween 80 (1 or 10 times the critical micelle concentration), and the addition of SRIF in a C:N:P ratio of 100:10:3. Three biometer flasks per combination of experimental conditions were incubated, and the performance of each treatment was examined by monitoring CO2 evolution, microbial activity, and oil degradation rate. The results suggest that the addition of inorganic nutrients accelerated the rate of CO2 evolution by a factor of 10. The application of oil-degrading microorganisms in a concentration greater than that of the indigenous population clearly increased biodegradation efficiency. The application of surfactant slightly enhanced the oil degradation rate in the contaminated sand treated with the higher concentration of oil-degrading microorganisms. The initial CO2 evolution rate was shown to efficiently evaluate the treatability test by providing significant data within a short period, which is critical for the rapid determination of the appropriate bioremediation approach. The measurements of microbial activity and crude oil degradation also confirmed the validity of the CO2 evolution rate as an appropriate criterion.     

Potential biomarkers of crude oil exposure in the gastropod mollusc,Austrocochlea porcata: laboratory and manipulative field studies

Surveys conducted after a crude oil spill indicated that the intertidal gastropod mollusc Austrocochlea porcata may be highly sensitive to the pollutant, and therefore also valuable as a biomonitoring organism. Toxicity tests conducted in the laboratory and field established cause-effect for A. porcata mortalities on exposure to environmentally relevant concentrations of crude oil constituents. Glutathione antioxidant system components (glutathione and glutathione peroxidase, GPx) and oxidative damage (lipid peroxidation) in A. porcata were measured to determine whether any of these biochemical parameters showed potential as biomarkers of sublethal oil exposure. GPx was the most promising candidate for field-based biomarker studies after showing a dose-dependent induction to a crude oil water accommodated fraction (WAF) in laboratory assays. However, subsequent manipulative field experimentation indicated that the GPx response was not sufficiently sensitive and not necessarily predictive of population level effects when measured in situ.     

A Strategy and Methodology for Defensibly Correlating Spilled Oil to Source Candidates

The source of crude oils and petroleum products released into navigable waterways and shipping lanes is not always known. Thus, the defensible identification of spilled crude oils and petroleum products and their correlation to suspected sources is a critical part of many oil spill assessments. Quantitative "fingerprinting" analysis, when evaluated using straightforward statistical and numerical analyses, provides a defensible means to differentiate among qualitatively similar oils and provides the best assessment of the source(s) for spilled oils. Polycyclic aromatic hydrocarbon (PAH) and petroleum biomarker concentration data are a particularly useful quantitative measure that can benefit most oil spill investigations. In this paper the strategy and methodology for correlation analysis that relies upon quantitative gas chromatography/mass spectrometry operated in the selected ion monitoring mode (GC/MS-SIM) is demonstrated in a case study involving 66 candidate sources for a heavy fuel oil spill of unknown origin. The strategy includes identification of 19 chemical indices (out of 45 evaluated) based upon PAH's and biomarkers that were (1) independent of weathering; and (2) precisely measured, both of which are determined by statistical analysis of the data. The 19 chemical indices meeting these criteria are subsequently analysed using principal component analysis (PCA), which helps to determine defensibly the "prime suspects" for the oil spill under investigation. The strategy and methodology described, which combines statistical and numerical analysis of quantitative chemical data, can be adapted and applied to other environmental forensic investigations with the objective of correlating any form of contamination to its suspected sources.     

Toxicity of crude oil to the mayfly, Hexagenia bilineata (Ephemeroptera: Ephemeridae)

Effects of crude oil on survival and behavior of the mayfly Hexagenia bilineata were evaluated in laboratory studies. Mayfly nymphs were exposed to the water soluble and oil residue fractions of crude oil. Mayfly survival was not reduced by a 96-h exposure to either the water soluble fraction or the oil residue mixed with sediment. However, significant mortality did result from a 21-day exposure to oil residue mixed with sediment at concentrations as low as 500 microg g(-1). Survival was also reduced after a 21-day exposure to oil-contaminated sediments (1905 microg g(-1)) collected 6 weeks after a crude oil spill in the Chariton River, Missouri. In a behavioral test measuring habitat exclusion, organisms did not avoid contact with sediment containing oil residue (50-800 microg g(-1)). Collectively, results from these studies indicate that exposure to oil residue in sediment will reduce survival of H. bilineata in the laboratory and may reduce survival in the environment for 6 weeks or more after an oil spill.