Biodegradation of aliphatic and aromatic hydrocarbons by natural soil microflora and pure cultures of imperfect and lignolitic fungi

The biodegradation of aliphatic and aromatic hydrocarbons by natural soil microflora and seven fungi species, including imperfect strains and higher level lignolitic species, is compared in a 90-day laboratory experiment using a natural, not-fertilized soil contaminated with 10% crude oil. The natural microbial soil assemblage isolated from an urban forest area was unable to significantly degrade crude oil, whereas pure fungi cultures effectively reduced the residues by 26-35% in 90 days. Normal alkanes were almost completely degraded in the first 15 days, whereas aromatic compounds (phenanthrene and methylphenanthrenes) exhibited slower kinetics. Aspergillus terreus and Fusarium solani, isolated from oil-polluted areas, produced the more efficient attack of aliphatic and aromatic hydrocarbons, respectively. Overall, imperfect fungi isolated from polluted soils showed a somewhat higher efficiency, but the performance of unadapted, indigenous, lignolitic fungi was comparable, and all three species, Pleurotus ostreatus, Trametes villosus and Coriolopsis rigida, effectively degraded aliphatic and aromatic components. The simultaneous, multivariate analysis of 22 parameters allowed the elucidation of a clear reactivity trend of the oil components during biodegradation: lower molecular weight n-alkanes > phenanthrene > 3-2-methylphenanthrenes > intermediate chain length n-alkanes > longer chain length n-alkanes > isoprenoids approximately 9-1-methylphenanthrenes. Irrespective of the individual degrading capacities, all fungi species tested seem to follow this decomposition sequence.     

Burial,exportation and degradation of acyclic petroleum hydrocarbons following a simulated oil spill in bioturbated Mediterranean coastal sediments

A field study was conducted in a French Mediterranean littoral (Gulf of Fos) in order to determine the role of bioturbation processes during the bioremediation of oil-contaminated sediments. Inert particulate tracers (luminophores) and Arabian light crude oil were deposited at the surface of sediment cores incubated in situ for 2, 6 and 12 months. After incubation, luminophores and hydrocarbons presented roughly similar depth distributions in the sediment, showing a continuous burial of material until 55 mm depth. Short-chain (< or = n-C25) n-alkanes were totally removed from the sedimentary column after 6 months, whereas approximately 20% of heavier n-alkanes (e.g. n-C30) and of isoprenoid hydrocarbons (pristane (Pr) and phytane (Ph)) remained at the end of the experiment. The determination of the degradation constant and the turn-over rate of individual hydrocarbon indicated that C17-25 n-alkanes were degraded two to three times faster than longer homologues and than pristane and phytane. Using the 17alpha,21beta-C30-hopane as an internal inert reference, we could demonstrate that, after 12 months of in situ incubation, 55% of the losses of the n-alkanes < or = C25 and 35% of the losses of the heavier n-alkanes and of Pr and Ph were due to biodegradation processes. These results demonstrate that the activity of benthic organisms can have a significant influence on the qualitative and quantitative fate of acyclic hydrocarbons following a petroleum contamination in marine coastal sediments.     

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.     

Influence of n-alkanes and petroleum on fatty acid composition of a hydrocarbonoclastic bacterium: Marinobacter hydrocarbonoclasticus strain 617

This study concerns the effects of various long-chain n-alkanes, n-alkane mixtures and Arabian Light crude oil on the fatty acid (FA) composition of a sedimentary marine bacteria (Marinobacter hydrocarbonoclasticus strain 617), growing under aerobic conditions. The cultures with n-alkanes, as compared with soluble carbon sources, led to greater amounts of saturated and methyl branched FA (mainly belonging to a delta10 series). We observed the appearance or increase of saturated and unsaturated FA with the same carbon chain length (CCL) as the n-alkane carbon source (maximum for n-alkane CCL corresponding to the 'range' of the de novo synthesized fatty acids). We also observed a strong control of the oddness/evenness of the CCL of the FA by the oddness/evenness of the n-alkane. A n-alkane utilization index, (saturated + branched)/monounsaturated fatty acids (SAFA + BFA/MUFA) enabled discriminating between soluble carbon sources and hydrocarbons.     

Climate change,future Arctic Sea ice,and the competitiveness of European Arctic offshore oil and gas production on world markets

A significant share of the world’s undiscovered oil and natural gas resources are assumed to lie under the seabed of the Arctic Ocean. Up until now, the exploitation of the resources especially under the European Arctic has largely been prevented by the challenges posed by sea ice coverage, harsh weather conditions, darkness, remoteness of the fields, and lack of infrastructure. Gradual warming has, however, improved the accessibility of the Arctic Ocean. We show for the most resource-abundant European Arctic Seas whether and how a climate induced reduction in sea ice might impact future accessibility of offshore natural gas and crude oil resources. Based on this analysis we show for a number of illustrative but representative locations which technology options exist based on a cost-minimization assessment. We find that under current hydrocarbon prices, oil and gas from the European offshore Arctic is not competitive on world markets.     

Photochemically induced interactions in Ekofisk crude oil

Evidence for photochemically induced interactions in Ekofisk crude oil as a thin film on top of a water surface has been obtained by isotopic labelling experiments and field desorbtion mass spectrometry. The interaction behaviour to the high molecular weight resin/asphaltene material has been discussed by invoking the concept of molecular assemblies like micelles and vesicles. This latter chromophoric material has also been shown to have an appreciable sensitizing effect, resulting in a substantial transformation of carbon 14 radiolabelled species, including straight chain n-alkanes.Isotopic studies do not provide evidence for interactions in Ekofisk crude oil constituents kept in darkness, where only a very slow transformation/degradation of oil components has been observed.The implication of these findings has been discussed.     

Assessment of crude oil biodegradation in arctic seashore sediments: effects of temperature,salinity, and crude oil concentration

The expected increase in offshore oil exploration and production in the Arctic may lead to crude oil spills along arctic shorelines. To evaluate the potential effectiveness of bioremediation to treat such spills, oil spill bioremediation in arctic sediments was simulated in laboratory microcosms containing beach sediments from Barrow (Alaska), spiked with North Slope Crude, and incubated at varying temperatures and salinities. Biodegradation was measured via respiration rates (CO₂ production); volatilization was quantified by gas chromatography/mass spectrophotometry (GC/MS) analysis of hydrocarbons sorbed to activated carbon, and hydrocarbons remaining in the sediment were quantified by GC/flame ionization detector (FID). Higher temperature leads to increased biodegradation by naturally occurring microorganisms, while the release of volatile organic compounds was similar at both temperatures. Increased salinity had a small positive impact on crude oil removal. At higher crude oil dosages, volatilization increased, however CO₂ production did not. While only a small percentage of crude oil was completely biodegraded, a larger percentage was volatilized within 6–9 weeks.     

Oil spill response capabilities and technologies for ice-covered Arctic marine waters: A review of recent developments and established practices

Renewed political and commercial interest in the resources of the Arctic, the reduction in the extent and thickness of sea ice, and the recent failings that led to the Deepwater Horizon oil spill, have prompted industry and its regulatory agencies, governments, local communities and NGOs to look at all aspects of Arctic oil spill countermeasures with fresh eyes. This paper provides an overview of present oil spill response capabilities and technologies for ice-covered waters, as well as under potential future conditions driven by a changing climate. Though not an exhaustive review, we provide the key research results for oil spill response from knowledge accumulated over many decades, including significant review papers that have been prepared as well as results from recent laboratory tests, field programmes and modelling work. The three main areas covered by the review are as follows: oil weathering and modelling; oil detection and monitoring; and oil spill response techniques.     

Crude oil and hydrocarbon-degrading strains of Rhodococcus rhodochrous isolated from soil and marine environments in Kuwait

Soil and marine samples collected from different localities in Kuwait were screened for microorganisms capable of oil degradation. Both fungi and bacteria were isolated. The fungal flora consisted of Aspergillus terreus, A. sulphureus, Mucor globosus, Fusarium sp. and Penicillum citrinum. Mucor globosus was the most active oil degrading fungus isolated. Bacterial isolates included Bacillus spp. Enterobacteriaceae, Pseudomonas spp., Nocardia spp., Streptomyces spp.,and Rhodococcus spp. Among these Rhodococcus strains were the most efficient in oil degradation and, relatively speaking, the most abundant. Bacterial and fungal isolates differed in their ability to degrade crude oil, with Rhodococcus isolates being more active that fungin in n-alkane biodegradation, particularly in the case of R. rhodochrous. In addition to medium chain n-alkanes, fungi utilized one or more of the aromatic hydrocarbons studied, while bacteria failed to do so. R. rhodochorous KUCC 8801 was shown by GLC and post-growth studies to be more efficient in oil degradation than isolates known to be active oil degraders.     

Interactive factors leading to dying-off Carex tato in Momoge wetland polluted by crude oil, Western Jilin, China

Momoge wetland is an internationally important wetland not only because it is a habitat for many rare bird species but also because it is an internationally important stopover for some rare global migratory bird species. However the petroleum exploitation in wetland has brought about many environmental problems. One of the most severe problems is crude oil pollution, which has caused the dying-off Carex tato and imposes great threat on survival of rare birds. This work studied the factors that caused the dying off of Carex tato. The results showed that death of Carex tato was the result narcosis toxicity of alcohols, intermediate biodegradation products of crude oil, on the root tissue, and the fragmentization of cuticle of leaves by light components of crude oil volatized from soil surface. However, the mechanism involved was much more complex and three interactive factors including crude oil pollution of soil, long-term drought and poor permeability of soil were responsible for the dying-off of Carex tato grassland. The distribution of crude oil in soil profile was characterized with high concentrations at top silty layer and the layer below root zone and low or no crude oil at root zone layer. This distribution was relative to root system characteristics and rhizospheric biodegradation. In root zone, substantive oxygen could be transported to root zone through dense root system and well developed aerenchyma. The crude oil in root zone was easily biodegraded by aerobic rhizosphere microbes. However, some toxic intermediate products, such as some alcohols, was sealed in root zone due to poor permeability of the top soil layer and the deeper soil layer and they had lethal effects on root tissue. Above ground, low molecular components of crude oil in top soil layer was easily volatized into atmosphere during long-term drought. Some of the volatized components were adsorbed onto leaves. SEM analysis showed that these components destroyed the leaves by fragmentization of cuticle of leave. This study also shows that although wetland has natural attenuation of pollutants, natural attenuation of pollutants by natural wetland should not be overemphasized. This attenuation function may lose under some conditions such as long-term drought and poor soil texture.     

Factors inhibiting bioremediation of soil contaminated with weathered oils and drill cuttings

Oily drill cuttings and a soil contaminated with weathered crude oils were treated by enhanced biodegradation under tropical conditions in industrial scaled experiments. Oil contaminants were characterized by gas chromatography and mass spectrometry. This allowed for the identification of a mixture of two crude oils in the contaminated soil. After 12 months of bioremediation process, the removal of hydrocarbons reached by biodegradation an extent of 60% although nutrient amendment with elevated concentration of N-urea had highly detrimental effects on the hydrocarbon degrading fungal populations due to the production of toxic concentration of ammonia gas by nitrification. The saturated hydrocarbons were extensively assimilated, though n-alkanes were not completely removed. Aromatic hydrocarbons were less degraded than saturated whereas resin and asphaltene fractions were, surprisingly, partly assimilated. In laboratory conditions, the residual hydrocarbons in the field-treated materials were 15-20% further degraded when metabolic byproducts resulting from biodegradation were diluted or removed.     

Petroleum Pollutant Degradation by Surface Water Microorganisms (8 pp)

Background, Aims and Scope It is well known that the composition of petroleum or some of its processing products changes in the environment mostly under the influence of microorganisms. A series of experiments was conducted in order to define the optimum conditions for an efficient biodegradation of petroleum pollutant, or bioremediation of different segments of the environment. The aim of these investigations was to show to what extent the hydrocarbons of a petroleum pollutant are degraded by microbial cultures which were isolated as dominant microorganisms from a surface water of a wastewater canal of an oil refinery and a nitrogen plant. Biodegradation experiments were conducted on one paraffinic, and one naphthenic type of petroleum during a three month period under aerobic conditions, varying the following parameters: Inorganic (Kp) or an organic medium (Bh) with or without exposition to light. Methods Microorganisms were analyzed in a surface water sample from a canal (Pančevo, Serbia), into which wastewater from an oil refinery and a nitrogen plant is released. The consortia of microorganisms were isolated from the water sample (most abundant species: Phormidium foveolarum - filamentous Cyanobacteria, blue-green algae and Achanthes minutissima, diatoms, algae). The simulation experiments of biodegradation were conducted with the biomass suspension and crude oils Sirakovo (Sir, paraffinic type) and Velebit (Ve, naphthenic type). After a three month period, organic substance was extracted by means of chloroform. In the extracts, the content of saturated hydrocarbons, aromatic hydrocarbons, alcohols and fatty acids was determined (the group composition). n-Alkanes and isoprenoid aliphatic alkanes, pristane and phytane, in the aliphatic fractions, were analyzed using gas chromatography (GC). Total isoprenoid aliphatic alkanes and polycyclic alkanes of sterane and triterpane types were analyzed by GC-MS. Results and discussion. Paraffinic type petroleums have a significant loss of saturated hydrocarbons. For naphthenic type petroleum, such a trend has not been observed. The most intensive degradation of n-alkanes and isoprenoid aliphatic alkanes (in paraffinic oil) and isoprenoids (in naphthenic oil) was observed using the inorganic medium Kp in the light; the microbial conversion is somewhat lower with Kp in the dark; with organic medium Bh in the light the degradation is of low intensity; with the same medium in the dark the degradation is hardly to be seen. Steranes and triterpanes were not affected by microbial degradation under the conditions used in our experiments. Obviously, the petroleum biodegradation was restricted to the acyclic aliphatics (n-alkanes and isoprenoids). Conclusion Phormidium foveolarum (filamentous Cyanobacteria - blue-green algae) and Achanthes minutissima (diatoms, algae), microbial cultures isolated as dominant algae from a surface water in a wastewater canal of an oil refinery and a nitrogen plant, have degradable effects dominantly involving petroleum hydocarbons. Petroleum microbiological degradation is more intensive when inorganic medium (in the light) is applied. Having in mind that the inorganic pollutants have been released into the canal as well, this medium reflects more the natural environmental conditions. Polycyclic alkanes of sterane and triterpane type, in spite of the fact that these compounds could be degraded, have remained unchanged regarding abundance and distribution. Since this is the case even for naphthenic type petroleum (which is depleted in n-alkanes), it can be concluded that the biodegradation of petroleum type pollutants, under natural conditions, will be restrained to the n-alkane and isoprenoid degradation. Recommendation and Outlook Performed experiments and simulations of petroleum microbiological degradation may serve for the prediction of the fate of petroleum type pollutants, as well as for definition of conditions for bioremediation of some environmental segments.     

Biodegradation of heavy crude oil Maya using spent compost and sugar cane bagasse wastes

Experiments were carried out to evaluate the use of some agroindustrial wastes as supports in solid state cultures for the biodegradation of crude oil Maya in static column reactors over 15-20 days periods. Spent compost and cane bagasse wastes showed superior qualities over peat moss waste as support candidates with the advantage that they contain appreciable densities of autochthonous microorganisms in the order of 10(2) cfu g(-1). Mercuric chloride (2%) was able to completely inhibit growth of these microfloras. Biodegradation was enhanced in the presence of the IMP consortium and highest when microflora from cane bagasse only was the bioaugmentation partner (180.7 mg kg(-1) day(-1)). Combination of these waste materials (3:1 ratio, respectively) was observed to significantly biodegrade the crude oil by approximately 40% in 15 days from an initial concentration of 10,000 mg kg(-1) with a four order of magnitude increase in microbial density during this period. Spent compost and cane bagasse wastes are veritable solid support candidates for use in the biodegradation of crude oil polluted systems.     

Long-Term Effects of Grazing and Global Warming on the Composition and Carrying Capacity of Graminoid Marshes for Moulting Geese in East Greenland

Greening of the Arctic due to climate warming may provide herbivores with richer food supplies, resulting in higher herbivore densities. In turn, this may cause changes in vegetation composition and ecosystem function. In 1982-1984, we studied the ecology of non-breeding moulting geese in Jameson Land, low Arctic East Greenland. By then, geese consumed most of the graminoid production in available moss fens, and it appeared that the geese had filled up the available habitat. In 2008, we revisited the area and found that the number of moulting geese and the temperature sum for June-July had tripled, while the above-ground biomass in a moss fen ungrazed by geese had more than doubled. In a goose-grazed fen, the overall plant composition was unchanged, but the frequency of graminoids had decreased and the area with dead vegetation and open spots had increased. We suggest that climate warming has lead to increased productivity, allowing for higher numbers of moulting geese. However, the reduction of vegetation cover by grazing may have longer term negative consequences for the number of geese the habitat can sustain.     

Impact of climate change and seasonal trends on the fate of Arctic oil spills

We investigated the effects of a warmer climate, and seasonal trends, on the fate of oil spilled in the Arctic. Three well blowout scenarios, two shipping accidents and a pipeline rupture were considered. We used ensembles of numerical simulations, using the OSCAR oil spill model, with environmental data for the periods 2009–2012 and 2050–2053 (representing a warmer future) as inputs to the model. Future atmospheric forcing was based on the IPCC’s A1B scenario, with the ocean data generated by the hydrodynamic model SINMOD. We found differences in “typical” outcome of a spill in a warmer future compared to the present, mainly due to a longer season of open water. We have demonstrated that ice cover is extremely important for predicting the fate of an Arctic oil spill, and find that oil spills in a warming climate will in some cases result in greater areal coverage and shoreline exposure.     

Influence of synthetic and biogenic surfactants on the toxicity of water-soluble fractions of hydrocarbons in sea water determined with the bioluminescence inhibition test

The influence of increasing amounts of surfactants on the toxicity of hydrocarbons was determined using the bioluminescence inhibition test (Microtox test). Three biogenic and three synthetic surfactants were tested against the water-soluble fractions (WSF) of crude and weathered Ekofisk oil, phenol, and naphthalene. Surfactant concentrations below 100 mg litre(-1) lowered the toxicity of the WSF, indicating an antagonistic interaction reducing the toxicities of surfactants and hydrocarbons. At concentrations greater than 100 mg litre(-1) the toxicity rose again and was higher than the untreated WSF. The point of reversal seemed to be the critical micelle concentration, at which the formation of oil/water emulsions is possible.     

Effect of crude oil contamination on the chlorophyll content and morpho-anatomy of Cyperus brevifolius (Rottb.) Hassk

Chlorophyll plays a pivotal role in the plant physiology and its productivity. Cultivation of plants in crude oil contaminated soil has a great impact on the synthesis of chlorophyll pigment. Morpho-anatomy of the experimental plant also shows structural deformation in higher concentrations. Keeping this in mind, a laboratory investigation has been carried out to study the effect of crude oil on chlorophyll content and morpho-anatomy of Cyperus brevifolius plant. Fifteen-day-old seedling of the plant was planted in different concentrations of the crude oil mixed soil (i.e., 10,000, 20,000, 30,000, 40,000, and 50,000 ppm). A control setup was also maintained without adding crude oil. Results were recorded after 6 months of plantation. Investigation revealed that there is a great impact of crude oil contamination on chlorophyll content of the leaves of the experimental plant. It also showed that chlorophyll a, chlorophyll b, and total chlorophyll content of leaves grown in different concentrations of crude oil were found to be lower than those of the control plant. Further, results also demonstrated that chlorophyll content was lowest in the treatment that received maximum dose of crude oil. It also showed that chlorophyll content was decreased with increased concentration of crude oil. Results also demonstrated that there was a reduction in plant shoot and root biomass with the increase of crude oil concentration. Results also revealed that the shoot biomass is higher than root biomass. Morphology and anatomy of the experimental plant also show structural deformation in higher concentrations. Accumulation of crude oil on the cuticle of the transverse section of the leaves and shoot forms a thick dark layer. Estimation of the level of pollution in an environment due to oil spill is possible by the in-depth study of the harmful effects of oil on the morphology and anatomy and chlorophyll content of the plants grown in that particular environment.     

Field investigation on the toxicity of Alaska North Slope crude oil (ANSC) and dispersed ANSC crude to Gulf killifish, Eastern oyster and white shrimp

A field investigation was conducted on a Louisiana Spartina alterniflora shoreline to evaluate the toxic effects of crude oil (Alaska North Slope crude oil, ANSC) and dispersed oil (ANSC + dispersant Corexit 9,500) on three aquatic species indigenous to the Gulf of Mexico: Fundulus grandis (Gulf killifish), Crassostrea virginica (Eastern oyster), and Litopenaeus setiferus (white shrimp). Results indicated that total hydrocarbons concentration value in oiled treatments decreased rapidly in 3h and were below 1 ppm at 24h after initial treatment. Corexit 9,500 facilitated more ANSC fractions to dissolve and disperse into the water column. L. setiferus showed short-term sensitivity to the ANSC and ANSC + 9,500 at 30 ppm. However, most test organisms (>83%) of each species survived well after 24h exposure to the treatments. Laboratory tests conducted concurrent with the field investigation indicated that concentrations of crude oil higher than 30 ppm were required for any significant toxic effect on the juvenile organisms tested.     

Oil spill cleanup using graphene

In this article, we study the use of thermally reduced graphene (TRG) for oil spill cleanup. TRG was synthesized by thermal exfoliation of graphite oxide and characterized by X-ray diffusion, Raman spectroscopy, SEM, TEM, elemental analysis, and Brunauer–Emmett–Teller (BET) surface area measurement. Various aspects of the sorption process have been studied including the sorption capacity, the recovery of the adsorbed oil, and the recyclability of TRG. Our results shows that TRG has a higher sorption capacity than any other carbon-based sorbents, with sorption capacity as high as 131 g of oil per gram TRG. With recovery of the sorbed oil via filtration and reuse of TRG for up to six cycles, 1 g of TRG collectively removes approximately 300 g of crude oil. Moreover, the effects of TRG bulk density, pore volume, and carbon/oxygen ratio and the oil viscosity on the sorption process are also discussed.     

Identifying source correlation parameters for hydrocarbon wastes using compound-specific isotope analysis

A preliminary evaluation of compound-specific isotope analysis (CSIA) as a novel, alternative method for identifying source correlation compounds in soils contaminated with residual heavy or weathered petroleum wastes is presented. Oil-contaminated soil microcosms were established using soil (sandy-loam, non-carbonaceous cley) amended with ballast-, crude- or No.6 fuel oil. Microcosms were periodically sampled over 256 days and delta(13)C values (which express the ratio of (13)C to (12)C) determined at each time point for five n-alkanes and the isoprenoid norpristane using gas chromatography-isotope ratio mass spectrometry (GC-IRMS). Although some temporal variation was observed, no significant temporal shifts in the delta(13)C values for the five n-alkanes were measured in all three oils. Isoprenoid isotope ratios (delta(13)C) appeared to be least affected by biotransformation, especially in the No.6 fuel oil. The research suggests that the delta(13)C of isoprenoids such as norpristane, may be of use as source correlation parameters.