Crude Oil In Soil Research Articles

Potential of vetiver (Vetiveria zizanioides (L.) Nash) for phytoremediation of petroleum hydrocarbon-contaminated soils in Venezuela

Venezuela is one of the largest oil producers in the world. For the rehabilitation of oil-contaminated sites, phytoremediation represents a promising technology whereby plants are used to enhance biodegradation processes in soil. A greenhouse study was conducted to determine the tolerance of vetiver (Vetiveria zizanioides (L.) Nash) to a Venezuelan heavy crude oil in soil. Additionally, the plant's potential for stimulating the biodegradation processes of petroleum hydrocarbons was tested under the application of two fertilizer levels. In the presence of contaminants, biomass and plant height were significantly reduced. As for fertilization, the lower fertilizer level led to higher biomass production. The specific root surface area was reduced under the effects of petroleum. However, vetiver was found to tolerate crude-oil contamination in a concentration of 5% (w/w). Concerning total oil and grease content in soil, no significant decrease under the influence of vetiver was detected when compared to the unplanted control. Thus, there was no evidence of vetiver enhancing the biodegradation of crude oil in soil under the conditions of this trial. However, uses of vetiver grass in relation to petroleum-contaminated soils are promising for amelioration of slightly polluted sites, to allow other species to get established and for erosion control.

Detailed compositional comparison of acidic NSO compounds in biodegraded reservoir and surface crude oils by negative ion electrospray Fourier transform ion cyclotron resonance mass spectrometry

Traditional hydrocarbon biomarker analyses determined the degree of biodegradation in two reservoir and two surface oils. These data were then correlated to the distribution and type (rings plus double bonds) of acidic NSO species selectively ionized and mass resolved by negative ion electrospray Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) to determine if oxygenated polars could be used to estimate the degree of biodegradation in crude-oil contaminated soil (surface) samples. Since the histories of the surface samples were unknown (as it often the case for environmental samples), non-degraded and severely degraded reservoir oils were used as compositional benchmarks. The biodegraded reservoir crude oil exhibited an increase in relative abundance of O 2-species, a decrease in acyclic fatty acids, an increase in multi-ring naphthenic acids and a decrease in C 32 hopanoic acids compared to the non-biodegraded reservoir crude oil. The surface oils exhibited trends similar to the biodegraded reservoir oil, indicating that the surface oils were biodegraded in the reservoir, the environment or both. However, one surface sample also exhibited biomarker signatures indicative of a non-degraded oil. This evidence, in combination with the ESI FT-ICR MS data, suggests that the sample was contaminated with a mixture of biodegraded and non-degraded oils and demonstrates how analysis of hydrocarbon and polar fractions can reveal complex histories of surface contamination. This work is the first detailed compositional analysis of acidic NSO species in crude oil soil extracts and lays the foundation for our understanding of how surface biodegradation effects the composition of polars.

The Effect of Triton X-100 on Biodegradation of Aliphatic and Aromatic Fractions of Crude Oil in Soil

The Effect of Triton X-100 on Biodegradation of Aliphatic and Aromatic Fractions of Crude Oil in Soil

Effect of Salinity on Biodegradation of Aliphatic Fractions of Crude Oil in Soil

Effect of Salinity on Biodegradation of Aliphatic Fractions of Crude Oil in Soil

Influence of fertilizer levels on phytoremediation of crude oil-contaminated soils with the tropical pasture grass Brachiaria brizantha (Hochst. ex A. Rich.) Stapf

Determination of fertilizer levels in phytoremediation of petroleum hydrocarbons is a complex issue, since nutrient demands of the plant and of degrading microorganisms in the rhizosphere have to be considered. In the present work, three fertilizer levels were tested in a greenhouse experiment with the aim of optimizing growth of the tropical pasture grass Brachiaria brizantha and enhance microbial degradation of heavy crude oil in soil. Fertilizer was applied twice in a concentration of 200, 300, and 400 mg each of N, P, and K per kg soil before and after the first sampling (14 wk). The medium fertilizer concentration resulted in best root growth and highest absolute oil dissipation (18.4%) after 22 wk. The highest concentration produced best shoot growth and highest relative oil dissipation after 14 wk (10.5% less than unplanted control). In general, degradation of total oil and grease was higher in planted than in unplanted soil, but differences diminished toward the end of the experiment. Next to fertilizer quantity, its composition is an important factor to be further studied, including the form of available nitrogen (N-NO 3 − vs. N-NH 4 +). Field trials are considered indispensable for further phytoremediation studies, since greenhouse experiments produce particular water and nutrient conditions.

Microbiological resilience of soils contaminated with crude oil

The effects of simulated crude oil soil contamination on microbial biomass, its activity and capacity to degrade crude oil hydrocarbons were examined in different soil types under different crop managements. The effect of the addition of different organic amendments (glucose, maize stalks and maize stalk compost) on microbial survival and crude oil degradation was also investigated. Microbial biomass was measured by the fumigation–extraction method and its activity was monitored by CO 2 evolution. Soil resilience was evaluated also from the amount of crude oil degraded at the end of the incubation (60 days at 25 °C). This ranged between 1% and 45% in unamended soils with an average of 31.3±3.8% and increased up to 36.4±2.1% in compost amended soils, although this difference was not significant. Less than 2% of crude oil was mineralized to CO 2 during 60 days of incubation, whereas more was irreversibly adsorbed (36–50%) and a smaller portion was lost by volatilization (10–33%). Crude oil caused a marked decrease in microbial biomass in Inceptisols (−25%), a small increase in Entisols (+5%) and a much larger increase in Mollisols (+53%). In Mollisols, microorganisms were better protected from the adverse effects of oil spills, and oil hydrocarbons were utilized as a carbon source, whereas in Inceptisols and Entisols, crude oil adversely affected the soil microbial populations, suggesting less resilience. Grassland soils, generally, better sustained the microorganisms in comparison to similar arable soils under maize monoculture. The addition of organic substrates (glucose, maize stalks and maize stalk compost) to contaminated soils had no synergistic effect on the decomposition of crude oil components but produced a marked increase in microbial biomass (21–36%). This increase was smaller than in uncontaminated soils (range 27–75%). The metabolic quotient increased markedly in contaminated soils from a mean of 1.24 up to 4.78 mg CO 2-C g −1 Bc h −1. Compost was the most effective amendment in reducing the metabolic quotient (2.36 mg CO 2-C g −1 Bc h −1), indicating a decrease in stress conditions caused by oil contamination. In Mollisols, the qCO 2 increased much less than in other soil types. No effects were observed on the decomposition rate of the different amendments indicating that decomposition of added substrates in soil was not significantly modified by crude oil contamination.

Stimulated Biodegradation of Crude Oil in Soil Amended with Periwinkle Shells

The potential of periwinkle shell (PS) in enhancing the microbial break down of crude oil spilled in soil were studied. The results revealed that the counts of crude oil degrading bacteria in oil-polluted soil fortified with PS were higher than the counts in unfortified soil. The rates and total extent of crude oil biodegradation in the soil were stimulated by the amendment. About 43.4 percent of crude oil was degraded in unfortified soil after 16 days as compared to 70.1 percent oil biodegradation, which occurred in PS fortified soil during the same period. These values were significantly (P>0.05) different from each other. Amendment of the soil with PS also raised the pH of the soil from acidic to alkaline range. The crude oil degrading microorganisms identified in PS amended soil were of the genus Pseudomonas, Bacillus, Micrococcus, Acinetobacter, Penicillium, Aspergillus, Mucor and Rhizopus. Similarly, Pseudomonas, Bacillus, Micrococcus, Mucor, Aspergillus and Penicillium were identified as crude oil degrading microorganisms in unamended soil. The bacteria formed either stable or unstable emulsions, suggesting that the organisms produce surface-active agents (biosurfactants) during the biodegradation process. The results of this study indicate that PS can be used in reclaiming oil-polluted soil.

Degradation of Crude Oil in the Rhizosphere of Sorghum bicolor

Dissipation of petroleum contaminants in the rhizosphere is likely the result of enhanced microbial degradation. Plant roots may encourage rhizosphere microbial activity through exudation of nutrients and by providing channels for increased water flow and gas diffusion. Phytoremediation of crude oil in soil was examined in this study using carefully selected plant species monitored over specific plant growth stages. Four sorghum (Sorghum bicolor L.) genotypes with differing root characteristics and levels of exudation were established in a sandy loam soil contaminated with 2700 mg crude oil/kg soil. Soils were sampled at three stages of plant growth: five leaf, flowering, and maturity. All vegetated treatments were associated with higher remediation efficiency, resulting in significantly lower total petroleum hydrocarbon concentrations than unvegetated controls. A relationship between root exudation and bioremediation efficiency was not apparent for these genotypes, although the presence of all sorghum genotypes resulted in significant removal of crude oil from the impacted soil.

Removal of Nigerian light crude oil in soil over a 12-month period

Abstract A study was carried out to aid in understanding the effect of various concentrations (10, 20, 30, 40% v/w) of Nigerian light crude oil (Transniger pipeline crude, TNP) deliberately spilled on soil will have on the indigenous bacterial population and the role of the bacteria in the removal of the oil. The average total counts of aerobic heterotrophs and crude oil utilizing bacteria in oil-impacted soils were 108 and 10 6 CFU/g , respectively, while in the untreated soil the total counts of the two groups of bacteria were low. The counts of the two groups of bacteria decreased with increasing oil concentration in the soil. Significantly higher numbers of total aerobic heterotrophs were recorded between May and July while those of crude oil utilizing bacteria were recorded between February and April probably due to differences in metabolic rates of the organisms as influenced by environmental conditions. The crude oil utilizing bacteria were identified as species of Bacillus, Pseudomonas, Vibrio, Micrococcus and Alcaligenes. The total extent of crude oil degradation by these organisms ranged from 26.7% to 43.3% after 16 days. GC analysis of the crude oil extracted from soil showed that hydrocarbon components C14 to C32 were extensively lowered in soil polluted with 10% and 20% (v/w) crude oil after 12 months but moderately lowered in soil treated with 30% (v/w) crude oil over the same period. In soil contaminated with 40% (v/w) of the same crude oil, minimal degradation of C14 to C32 was observed. The results indicate that the quantity of crude oil spilled in soil and the age of the contamination influence the rate and total extent of disappearance of the oil in the environment.

Earthworm survival in oil contaminated soil

Earthworms are an important component of the soil biota and their response to oil pollution needs to be better understood. Laboratory investigations were undertaken to determine the concentrations of crude oil in soil that leads to death of Lumbricus terrestris and Eisenia fetida and to determine the propensity of L. terrestris to move away from contaminated soil. Clemville sandy clay loam was amended to contain maximum oil contents of 1.5 – 2.5% depending on the particular experiment. Additionally, the ability of L. terrestristo survive in bioremediated oil-contaminated soil was evaluated. An oil content of 0.5% was not harmful to survival of earthworms for 7 d but an oil concentration of 1.5% reduced survival to less than 40%. Bioremediated soil containing 1.2% oil did not reduce survival of L. terrestrisduring 10 d. Survival of L. terrestrisin unweathered oil was improved when free movement between contaminated and uncontaminated soil was possible. Casts of earthworms exposed to oil-containing soil contained 0.2% total petroleum hydrocarbons. An allowable regulatory level of 1% oil contamination in soil may not allow for survival of earthworms.

Managed bioremediation of soil contaminated with crude oil soil chemistry and microbial ecology three years later

Analysis of samples taken from three experimental soil lysimeters demonstrated marked long-term effects of managed bioremediation on soil chemistry and on bacterial and fungal communities 3 yr after the application of crude oil or crude oil and fertilizer. The lysimeters were originally used to evaluate the short-term effectiveness of managed (application of fertilizer and water, one lysimeter) vs unmanaged bioremediation (one lysimeter) of Michigan Silurian crude oil compared to one uncontaminated control lysimeter. Three years following the original experiment, five 2-ft-long soil cores were extracted from each lysimeter, each divided into three sections, and the like sections mixed together to form composited soil samples. All subsequent chemical and microbiological analyses were performed on these nine composited samples. Substantial variation was found among the lysimeters for certain soil chemical characteristics (% moisture, pH, total Kjeldahl nitrogen [TKN], ammonia nitrogen [NH4-N], phosphate phosphorous [PO4-P], and sulfate [SO4 (-2)]). The managed lysimeter had 10% the level of total petroleum hydrocarbons (TPH-IR) found in the unmanaged lysimeter. Assessment of the microbial community was performed for heterotropic bacteria, fungi, and aromatic hydrocarbon-degrading bacteria (toluene, naphthalene, and phenanthrene) by dilution onto solid media. There was little difference in the number of heterotrophic bacteria, in contrast to counts of fungi, which were markedly higher in the contaminated lysimeters. Hydrocarbon-degrading bacteria were elevated in both oil-contaminated lysimeters. In terms of particular hydrocarbons as substrates, phenanthrene degraders were greater in number than naphthalene degraders, which outnumbered toluene degraders. Levels of sulfate-reducing bacteria seem to have been stimulated by hydrocarbon degradation.

API's Decision Support System (DSS) Applied in a Site Assessment for Residual Crude Oil in Soil: Case Study in Kern County, California: ABSTRACT

Historical crude oil leaks from a pipeline have impacted soil near a sensitive ground-water recharge area in Kern County, California. The residual crude oil in soil is confined to the vadose zone, and occurs from about 10 feet below ground surface (bgs) to a maximum depth of 80 feet bgs. The water table beneath the impacted soil is currently 159 feet bgs. The site is irrigated regularly for agriculture. Ground water has not been affected. Future ground-water recharge plans may raise the water table to 50 feet bgs near the area of the impacted soil. Fate and transport modeling with site-specific data was used to determine if the existing hydrocarbons in the soil pose a significant risk to ground water quality. The computer models selected for this project are incorporated as modules in the American Petroleum Institute`s (API`s) Exposure and Risk Assessment Decision Support System (DSS). Transport of BTEX compounds was modeled using SESOIL for the unsaturated zone, coupled with AT123D for the saturated zone. The SESOIL model was calibrated using actual soil moisture measurements and ground-water recharge estimates based on applied irrigation. Peak BTEX concentrations in ground water predicted for the site are well below maximum contaminant levels. Amore » sensitivity analysis affirmed that aerobic biodegradation significantly reduces BTEX compounds. Due to the high availability of dissolved oxygen in the ground water at this site, natural attenuation may be the most viable mechanism to remediate BTEX compounds in the soil.« less

Alternatives for In-Situ Remediation for Crude Oil in Soil and Groundwater

Alternatives for In-Situ Remediation for Crude Oil in Soil and Groundwater

Evaluation of Environmental and Human Risk From Crude-Oil Contamination

Summary The presence of petroleum compounds in soils, water, or petroleum compoundsin soils, water, or air does not necessarily result in a risk to populations. This paper presents a method of quantitative risk assessment (QRA) usedsuccessfully to assess, describe, and understand the environmental- andhuman-heath risks found in the oilfield environment. Introduction Soil contamination from petroleum hydrocarbons has become an important humanand environmental-health issue in the U.S. over the last decade. Yet, thiscontamination has probably occurred since the use of petroleum becamewidespread during the petroleum became widespread during the early part of thiscentury. The potential exists for humans to be exposed to petroleumconstituents in soils through various pathways. Potential pathways of exposureto pathways. Potential pathways of exposure to petroleum hydrocarbons in soilat a site depend petroleum hydrocarbons in soil at a site depend on the type ofsoil, petroleum, and petroleum constituents present. petroleum constituentspresent. Potential human exposures to petroleum in soils can be evaluatedthrough the use of formal QRA. This method incorporates information about thetoxicity of the petroleum and its constituents. the environmental behavior ofthese agents. and the estimated exposure to these agents to evaluate thepossible health risks to humans exposed to possible health risks to humansexposed to petroleum in soil. petroleum in soil. Crude oil is the naturallyoccurring liquid phase of petroleum. Natural crude-oil seeps are common inregions of petroleumbearing formations. This natural petroleumbearingformations. This natural contamination may result in human exposures to crudeoil and subsequent associated health risks. Risks from natural contaminationsources are often referred to as background risks. Health risks associated withexposures resulting from accidental releases of chemicals into the environmentare referred to as additional or incremental risks. QRA's are used to evaluateincremental health risks from accidental releases of petroleum products intothe environment. For example, if products into the environment. For example, ifa QRA concludes that the presence of crude oil in soil results in exposuresthat may cause adverse effects, then the concentration of the crude in soil mayneed to be reduced to an acceptable level. Use of Risk Assessment. Companies use formal health-based risk assessmentfor a variety of reasons, including the need to understand risks and toprioritize the remediation and prevention of risk. Internally, companies wantto understand the potential risks at a given site for decision-making reasonsand for comparison with other sites. The QRA provides information that cananswer a variety of internal questions. For example, how can one company withmultiple sites contaminated with a variety of chemicals prioritize remediationalternatives? How can a company develop a structured enviroinmental program toremediate each of those sites when the given fiscal reality does not permitremediation of all sites in a given year? Companies can use QRA's to prioritizethe sites and clean up the most risky sites first. This equates to a program ofrisk prevention in which the greatest amount of prevention in which thegreatest amount of risk reduction is achieved for every remediation dollarspent. QRA's can also be used to prioritize the remediation within a givensite. The chemical with the highest concentration may not be the chemical withthe highest risk. Use of QRA's within a site allows, first, for the remediationof chemical contaminants that pose the highest risk to the exposed population, with subsequent remediation of the remaining chemical contaminants having lowerrisk. Externally, QRA's are used in a variety of situations, includingregulatory responses and dealings with the public and media. QRA's can providealternative contamination levels or remediation goals at a given site and canbe used to convey the conditions at the site to the public and media. QRA's arescientifically defensible documents, based on the best and most currentunderstanding of the toxicity and exposure data base, that provide a logical, documented transition from site-specific exposure and toxicity data to theestimated risk. As legal documents, QRA's are used in liability cases and inthe defense of product liability suits. QRA's provide a structure to theremediation process and address an endpoint; they can be used to provide analternative remediation goal to one being proposed by regulators-i.e., arisk-driven rather than technology-driven remediation endpoint. QRA Components. The principle of risk assessment can be summed up as hazardtimes exposure equals risk. JPT P. 14

Low‐Temperature Mineralization of Crude Oil in Soil

AbstractPrudhoe Bay crude oil was added at 0,3, and 6% wt oil to wt of soil in a laboratory study designed to evaluate methods of enhancing crude oil mineralization at 10°C. Both mechanical stirring of the soil and fertilization were effective in enhancing mineralization. Under the most favorable conditions of the study at the 3 and 6% loading rates, respectively, only 18.9 and 11.9% of the added C was evolved as CO2. Nitrogen appeared to be the most stimulatory fertilizer; however, phosphorus in addition to nitrogen further enhanced C mineralization. Sulfur or a combined assortment of other macro‐ and micronutrients was not beneficial when added to nitrogen and phosphorus fertilizers. Sawdust was added to decrease the hydrophobic nature of oiled soils and to improve soil physical properties. Although added sawdust lessened aggregation of the stirred soil, degradation of the oil was not enhanced. Aerobic bacteria and actinomycetes were both initially active shortly after oil addition. This was followed somewhat later by population increases of bacteria growing anaerobically. Oil additions had no stimulatory effect on fungal populations. Doubling time of the net aerobic bacterial population was calculated to be 2.0 days in unfertilized soil receiving 6% oil. In fertilized soil receiving the same rate of oiling, the corresponding time was 1.2 days. Thus, fertilization decreased the doubling interval of indigenous bacteria by approximately 40% in this study conducted at 10°C.