Petroleum Hydrocarbons In Soil Research Articles

Comparison of landfarming amendments to improve bioremediation of petroleum hydrocarbons in Niger Delta soils

Large scale landfarming experiments, using an extensive range of treatments, were conducted in the Niger-Delta, Nigeria to study the degradation of oil in contaminated soils. In this work the effect of nutrient addition, biosurfactant, Eisenia fetida (earthworm) enzyme extract, bulking and sorption agents and soil neutralization were tested. It was found that these treatments were successful in removing up to 53% of the total petroleum hydrocarbon in the soil within 16 weeks. A comparison between treatments demonstrated that most were no more effective than agricultural fertilizer addition alone. One strategy that did show better performance was a combination of nutrients, biochar and biosurfactant, which was found to remove 23% more Total Petroleum Hydrocarbons (TPH) than fertilizer alone. However, when performance normalized costs were considered, this treatment became less attractive as a remedial option. Based on this same analysis it was concluded that fertilizer only was the most cost effective treatment. As a consequence, it is recommended that fertilizer is used to enhance the landfarming of hydrocarbon contaminated soils in the Niger Delta.The attenuation rates of both bulk TPH and Total Petroleum Hydrocarbon Criteria Working Group (TPHCWG) fractions are also provided. These values represent one of the first large scale and scientifically tested datasets for treatment of contaminated soil in the Niger Delta region. An inverse correlation between attenuation rates and hydrocarbon molecular weight was observed with heavy fractions showing much slower degradation rates than lighter fractions. Despite this difference, the bioremediation process resulted in significant removal of all TPH compounds independent of carbon number.

Evaluation of the use of legumes for biodegradation of petroleum hydrocarbons in soil

The aim of this research was to evaluate the potential of six legumes: Medicago sativa L., Glycine max, Arachis hypogea, Lablab purpureus, Pheseolus vulgaris and Cajanus cajan to restore within a short period of time soil contaminated with 3% crude oil. The legumes in five replications were grown in crude oil-contaminated and crude oil-uncontaminated soil in a completely randomized design. Plants were assessed for seedling emergence, plant height and leaf number. GC–MS was used to analyze the residual crude oil from the rhizosphere of the legumes. Plant growth parameters were reduced significantly (P < 0.05) for legumes in contaminated soil compared to their controls. In the 4th week after planting (WAP), shoot height increased across the species up to the 8th WAP. However, in the 12 WAP no significant increase in the shoot of all species was observed. Two WAP legumes planted in contaminated soil had significantly (P < 0.05) higher leaf number than these planted in uncontaminated soil with the exception of M. sativa. In the 4th WAP, only A. hypogea and P. vulgaris had increased leaf number, while in the 6th WAP, only L. purpureus had increased leaf number and survived up to the 12th WAP while most of the legumes species died. Chromatographic profiles indicated 100% degradation of the oil fractions in C. cajan and L. purpureus after 90 days. For other legumes however, greater losses of crude oil fractions C1–C10 and C10–C20 were indicated in rhizosphere soil of P. vulgaris and G. max, respectively. The most effective removal (93.66%) of C21–C30 components was observed in G. max-planted soil even though vegetation was not established. The legumes especially C. cajan, L. purpureus and A. hypogea are promising candidates for phytoremediation of petroleum hydrocarbon-impacted soil.

Interpreting Interactions between Ozone and Residual Petroleum Hydrocarbons in Soil.

We evaluated how gas-phase O3 interacts with residual petroleum hydrocarbons in soil. Total petroleum hydrocarbons (TPH) were 18 ± 0.6 g/kg soil, and TPH carbon constituted ∼40% of the dichloromethane-extractable carbon (DeOC) in the soil. At the benchmark dose of 3.4 kg O3/kg initial TPH, TPH carbon was reduced by nearly 6 gC/kg soil (40%), which was accompanied by an increase of about 4 gC/kg soil in dissolved organic carbon (DOC) and a 4-fold increase in 5-day biochemical oxygen demand (BOD5). Disrupting gas channeling in the soil improved mass transport of O3 to TPH bound to soil and increased TPH removal. Ozonation resulted in two measurable alterations of the composition of the organic carbon. First, part of DeOC was converted to DOC (∼4.1 gC/kg soil), 75% of which was not extractable by dichloromethane. Second, the DeOC containing saturates, aromatics, resins, and asphaltenes (SARA), was partially oxidized, resulting in a decline in saturates and aromatics, but increases in resins and asphaltenes. Ozone attack on resins, asphaltenes, and soil organic matter led to the production of NO3-, SO42-, and PO43-. The results illuminate the mechanisms by which ozone gas interacted with the weathered petroleum residuals in soil to generate soluble and biodegradable products.

Use of Rice Husk as Bulking Agent in Bioremediation of Automobile Gas Oil Impinged Agricultural Soil

ABSTRACTEvaluation of rice husk (RH) as bulking agent in bioremediation of automobile gas oil (AGO) hydrocarbon polluted agricultural soil using renewal by enhanced natural attenuation (RENA) as control was the subject of the present investigation. The effect of different parameters such as total petroleum hydrocarbon (TPH), dehydrogenase activity (DHA), optical density and pH on bioremediation performance were evaluated. The studied parameters such as microbial dynamics, percentage degradation and DHA were found to be higher in RH-amended system and differed significantly with control at P < 0.05. RH resulted in high removal efficiency of 97.85 ± 0.93% under a two-month incubation period, while RENA had lesser removal efficiency of 53.15 ± 3.81%. Overall hydrocarbon biodegradation proceeded very slowly in the RENA particularly from week 0 to 4. Experimental data perfectly fitted into the first-order kinetic and generated high r2 values (0.945), first-order degradation constant (0.47 day−1), and shorter degradation half-life (1.50 d)—t1/2 = Ln2/K and Ln2 numerically equals to 0.693 and hence written as 0.693/K. Micrococcus luteus and Rhizopus arrhizus were isolated in the present study, which displayed extreme AGO hydrocarbon biodegradative abilities. The use of RH in hydrocarbon-polluted soil significantly increased biodegradation rate and resulted in effective AGO cleanup within 2 months period. Therefore, RH provides an alternative source of bioremediation material in field application for abundant petroleum hydrocarbon soil pollution.

Comparison of the phytoremediation potentials of Medicago falcata L. And Medicago sativa L. in aged oil-sludge-contaminated soil.

Thirteen-year monitoring of the vegetation growing in the industrial and adjacent areas of an oil refinery showed the prevalence of yellow medick (Medicago falcata L.) over other plant species, including alfalfa (Medicago sativa L.). A comparative field study of the two Medicago species established that yellow medick and alfalfa exhibited similar resistance to soil petroleum hydrocarbons and that the pollutant concentration in their rhizosphere was 30% lower than that in the surrounding bulk soil. In laboratory pot experiments, yellow medick reduced the contaminant content by 18% owing to the degradation of the major heavy oil fractions, such as paraffins, naphthenes, and alcohol and benzene tars; and it was more successful than alfalfa. Both species were equally effective in stimulating the total number of soil microorganisms, but the number of hydrocarbon-oxidizing microorganisms, including polycyclic aromatic hydrocarbon degraders, was larger in the root zone of alfalfa. In turn, yellow medick provided a favorable balance of available nitrogen. Both Medicago species equally stimulated the dehydrogenase and peroxidase activities of the soil, and yellow medick increased the activity of soil polyphenol oxidase but reduced the activity of catalase. The root tissue activity of catalase, ascorbate oxidase, and tyrosinase was grater in alfalfa than in yellow medick. The peroxidase activity of plant roots was similar in both species, but nondenaturing polyacrylamide gel electrophoresis showed some differences in the peroxidase profiles of the root extracts of alfalfa and yellow medick. Overall, this study suggests that the phytoremediation potentials of yellow medick and alfalfa are similar, with some differences.

Treatment of soil co-contaminated with inorganics and petroleum hydrocarbons using silica: Implications for remediation in cold regions

Successful remediation of contaminated land in cold regions is challenged by freeze-thaw cycling, slow rates of natural hydrocarbon attenuation, extreme weather and financial and logistical constraints. At sites co-contaminated with metals and petroleum hydrocarbons, microbial activity is suppressed and biodegradation of petroleum hydrocarbons is also slowed. This study assesses the performance of eight silica treatments for immobilising inorganics (Al, Cr, Fe, Ni, Cu, Zn, As, Cd and Pb) and encapsulating petroleum hydrocarbons (a winterised diesel) in co-contaminated soil at 2°C. Treatments containing orthophosphoric acid immobilised Cu, Zn, Cd and Pb, but mobilised As. The formation of hydroxypyromorphite, sodium aluminosilicates and calcium bearing minerals were observed following treatment, demonstrating the potential for successful immobilisation of inorganics using silica treatments. Silica treatments were less effective at reducing total extractable concentrations of petroleum hydrocarbons in soil, indicating that further research is required to optimise treatment performance in soil co-contaminated with inorganics and petroleum hydrocarbons.

The Willow Microbiome Is Influenced by Soil Petroleum-Hydrocarbon Concentration with Plant Compartment-Specific Effects.

The interaction between plants and microorganisms, which is the driving force behind the decontamination of petroleum hydrocarbon (PHC) contamination in phytoremediation technology, is poorly understood. Here, we aimed at characterizing the variations between plant compartments in the microbiome of two willow cultivars growing in contaminated soils. A field experiment was set-up at a former petrochemical plant in Canada and after two growing seasons, bulk soil, rhizosphere soil, roots, and stems samples of two willow cultivars (Salix purpurea cv. FishCreek, and Salix miyabeana cv. SX67) growing at three PHC contamination concentrations were taken. DNA was extracted and bacterial 16S rRNA gene and fungal internal transcribed spacer (ITS) regions were amplified and sequenced using an Ion Torrent Personal Genome Machine (PGM). Following multivariate statistical analyses, the level of PHC-contamination appeared as the primary factor influencing the willow microbiome with compartment-specific effects, with significant differences between the responses of bacterial, and fungal communities. Increasing PHC contamination levels resulted in shifts in the microbiome composition, favoring putative hydrocarbon degraders, and microorganisms previously reported as associated with plant health. These shifts were less drastic in the rhizosphere, root, and stem tissues as compared to bulk soil, probably because the willows provided a more controlled environment, and thus, protected microbial communities against increasing contamination levels. Insights from this study will help to devise optimal plant microbiomes for increasing the efficiency of phytoremediation technology.

Influence of humic acid on biodegradation of petroleum hydrocarbons in oil-contaminated soils

ABSTRACTThis study evaluated the use of humic acid (HA) to enhance biodegradation of petroleum hydrocarbons in a soil contaminated with diesel oil at an initial total petroleum hydrocarbons (TPH) concentration of 5000 mg kg−1 soil (0.5%). The HA was characterized using Fourier transform infrared (FTIR) spectroscopy. Six pans of 0.5% diesel oil-contaminated soil were prepared—three pans were supplemented with three rates of HA (10, 20, and 30g HA kg−1 soil) and urea, one pan was supplemented with only urea, another pan was without any amendment (control), and the sixth pan was supplemented with a diesel-oil-contaminated soil that was steam-sterilized (nonbiologically active soil) . These pans were used to investigate the effects of HA on the biodegradation of TPHs and the population of hydrocarbon-utilizing bacteria (HUB) by measuring residual concentration of TPH and microbial count, respectively, during a 75-day incubation experiment. At the end of the incubation, the lowest reduction in TPH concentration was observed in the sterilized soil. The TPH in HA amended pans had reduced from 55.55 to 80.70%, while other biologically active soils recorded reductions between 21.39 and 32.59%. The pan containing only nutrient recorded lower concentration of TPH (32.59%) compared to the control (21.39%). The HA-amended pans also recorded highest count of HUB that ranged between 3.6 × 106 and 11.5 × 106 cfu g−1. The pan containing only urea recorded HUB count of 5.9 × 106 cfu g−1, while the control had HUB count of 2.2 × 106 cfu g−1. The results of this study showed that HAs enhanced biodegradation of petroleum hydrocarbons and also stimulated the proliferation of soil bacteria.

Rapid prediction of total petroleum hydrocarbons in soil using a hand-held mid-infrared field instrument

This manuscript reports on the performance of a hand-held diffuse reflectance (mid)-infrared Fourier transform (DRIFT) spectrometer for the prediction of total petroleum hydrocarbons (TPH) in three different diesel-contaminated soils. These soils include: a carbonate dominated clay, a kaolinite dominated clay and a loam from Padova Italy, north Western Australia and southern Nigeria, respectively. Soils were analysed for TPH concentration using a standard laboratory methods and scanned in DRIFT mode with the hand-held spectrometer to determine TPH calibration models. Successful partial least square regression (PLSR) predictions, with coefficient of determination (R2) ~0.99 and root mean square error (RMSE) <200mg/kg, were obtained for the low range TPH concentrations of 0 to ~3,000mg/kg. These predictions were carried out using a set of independent samples for each soil type. Prediction models were also tested for the full concentration range (0–60,000mg/kg) for each soil type model with R2 and RMSE values of ~0.99 and <1,255mg/kg, respectively. Furthermore, a number of intermediate concentration range models were also generated for each soil type with similar R2 values of ~0.99 and RMSE values <800mg/kg. This study shows the capability of using a portable mid-infrared (MIR) DRIFT spectrometer for predicting TPH in a variety of soil types and the potential for being a rapid in-field screening method for TPH concentration levels at common regulatory thresholds.A novel hand-held mid-infrared instrument can accurately detect TPH across different soil types and concentrations, which paves the way for a variety of applications in the field.

Numerical Simulation of Plant–microbial Remediation for Petroleum-polluted Soil

ABSTRACTThis paper presents a numerical analysis of the migration and transformation mechanism of petroleum hydrocarbons (PHs) pollutants in soil. The mathematical model of the solute migration and plant–microbial remediation for PH polluted soil was established. The model was verified by field experimental data. Then, the software Hydrus-1D was employed to simulate the processes of diffusion, adsorption, desorption, microbial degradation, and plant adsorption of PHs in the soil–water system. The process of plant–microbial remediation for PH-contaminated soil was also simulated. The space-time change of PHs in soil was obtained, and the fate and remediation efficiency of PHs in soil were revealed in different remediation conditions. The results indicated that the Hydrus-1D model can adequately simulate the process of plant–microbial remediation. Plant–microbial remediation appears to be more efficient than the application of bacteria or Suaeda salsa. The majority of PH pollutants are degraded in the upper soil levels. For long-chain petro-alkane-contaminated soil, plant–microbial remediation is a more efficient method. A suitable moisture level in soil is important for improving the bioremediation effect of plant–microbial remediation technology.

Consistency between health risks and microbial response mechanism of various petroleum components in a typical wastewater-irrigated farmland

Various petroleum components possess distinctive migration and toxicity characteristics. Evaluation of contamination levels on the basis of total concentrations of petroleum hydrocarbons in soil and groundwater is limited. Hunpu, a typical wastewater-irrigated area, is located at the southwest of Shenyang City, Liaoning Province, China. In this study, various fractions, exposure pathways, and soil microbial communities were taken into account to make petroleum contamination evaluation more effective and precise in the region. The concentrations and hazard quotients of aliphatic fractions, as the bulk of an oil, verified that the groundwater must not be drunk directly. The total concentrations of aliphatic hydrocarbons (TAHs) for C10–34 were 68.90–199.87 μg g−1 in soil in Hunpu, which required cleanup according to Oklahoma criteria. However, both health and ecological risks indicated that petroleum contamination in surface soil was not serious. Microbes may use aliphatic fractions as carbon and energy source for their growth, which was indicated by positive correlation between them. TAHsC12–16 posed highest human health risks and had the most significant effect on the soil microbial composition, although its concentration was low in both the groundwater and the soil. Straight-, branched-chain saturated, and cyclopropyl phospholipid fatty acids had more closely positive correlation with TAHsC12–16, which indicated that regulation of bacterial membrane fluidity to toxic petroleum pollutants. This study can also provide the guidelines for assessment and management of petroleum contamination.

Potential biodegradation of crude petroleum oil by newly isolated halotolerant microbial strains from polluted Red Sea area

Two microbial isolates from oil polluted Red Sea water in Egypt, designated as RS-Y1 and RS-F3, were found capable of degrading Belayim mix (BX) crude oil. Strains RS-Y1 and RS-F3 were assigned to the genera Lipomyces tetrasporus and Paecilomyces variotii based on their morphological and physiological characteristics. Both isolates were compared for the biodegradation of crude petroleum-oil hydrocarbons in basal salt medium supplemented with 5% (w/v) of BX-crude oil. Gas chromatography profile showed that the biodegradation of total petroleum hydrocarbons (TPHs) inoculated with L. tetrasporus (68.3%) and P. variotii (58.15%) along with their consortium (66%) significantly reduced TPHs levels as compared to the control after 30days. L. tetrasporus (44.5%) was more effective than P. variotii strain (32.89%) in reducing the unresolved complex mixtures (UCM) content from the medium. Both isolates exhibited a strong growth over a wide range of salinity (5–45g/L NaCl).

Bioremediation Rate of Total Petroleum Hydrocarbons from Contaminated Water by Pseudomonas aeruginosa Case Study: Lake Albert, Uganda

Uganda is currently exploiting petroleum products. This is mainly around the fresh water bodies. However, these water bodies are habitants for several aquatic organisms and also the main drinking water sources. Despite the fact that they are known for several uses both ecological and economical, they are likely to be seriously polluted by crude oil petroleum hydrocarbons (PHs). Therefore they will require to be treated by ecologically friendly methods. Pseudomonas aeruginosa naturally habits Ugandan water bodies and it’s known for no health hazards to human (after boiling the water) and to aquatic organisms. Therefore multiplying its numbers in aquatic environments has no health implications yet it’s known for degrading PHs. Thus the current study aimed at determining the rate at which Pseudomonas aeruginosa can remediate PHs from water of Lake Albert. Method: Water from Lake Albert was collected to laboratory, contaminated with 10% m/v PHs (100g/L). This was then inoculated with Pseudomonas aeruginosa (turbidity of 0.04 absorbance at a wave length of 600 nm) in a 1cm cuvette containing about 3.0×107 colony-forming unit (CFU)/mL. The waters were left at room temperatures to replicate the temperature of the natural water body in Uganda. Results: Results showed that the initial rate, Rbioi was 32.3 g/liter per day for n-hexane soluble PHs. Also, the maximum amount removed when the rate reduced to zero was 89.3/liter. The bioremediation process followed second order kinetics with half-life of 3.9 days. This means the original amount will reduce to half the original amount after 3.9 days (about 93.6 hrs). Pseudomonas aeruginosa significantly (p=0.03) (p<0.05) remediates PHs from Lake Albert water with maximum removal rate between day 1 and day 3. However, physico-chemical factors for example temperature, pH were not investigated in this current study.

State and federal cleanup levels for petroleum hydrocarbons in soil: State of the states and implications for the future

ABSTRACTThe Association for Environmental Health and Sciences Foundation has been collecting information on state-by-state petroleum cleanup levels (CULs) for soil since 1990, with the most recent survey in 2012. These data form the basis for this analysis, including a comparison of the CULs to U.S. Environmental Protection Agency (USEPA) regulatory values. The results illustrate the evolving complexity of state regulatory approaches to petroleum mixtures; benzene, toluene, ethylbenzene, and xylenes; and carcinogenic polycyclic aromatic hydrocarbons, as well as the use of multiple exposure scenarios and pathways to regulate petroleum in soil. Different fractionation approaches in use by various states and the USEPA are discussed, their strengths and limitations are reviewed, and their implications for site CULs are evaluated. Because of an increasing array of scenarios and pathways, CUL ranges have widened over time. As the regulatory environment for petroleum releases becomes more complex, it is increasingly important to develop a conceptual site model for fate, transport, land use assumptions, and exposure pathways at petroleum-contaminated sites to enable selection of the most appropriate CULs available.

Determination of oil and oil products total content in soils for monitoring of contamination and effectiveness of remediation

The method of determining the content of oil and petroleum products in the soils is substantiated through the use established by thermogravimetric curves optimum temperatures and time intervals thermal sample of contaminated soil, determination of total losses its weight on the appropriate formula which ensures the quantitative determination of total content level of hydrocarbons of oil and oil products in the soil with increased accuracy and quick testing of the method. In the methodical approach by combining individual components of the known methods thermogravimetry and gas chromatography, the distribution regularities of changes in the sample mass under the influence of thermal effects on a new class of objects with simultaneous production of a rapid method for determination of total content of petroleum hydrocarbons in soils, provided simplification soil samples algorithm analyzing for pollution monitoring and the remediation effectiveness of obtaining the economic use of resources. The invention belongs to the field of environmental protection, soil quality, namely to the ways of determine the content of oil and petroleum products (diesel, kerosene, fuel oil, etc.) in contaminated soils while of soils lands plot monitoring. The method can be used in the field of conservancy in the oil industrial complex in determining the degree of contamination of soil for rapid analysis of soil samples; in agroecology, soil ecological management for environmental monitoring of technologically contaminated soils of lands plots for various purposes and their using; in research practice - to investigate the thermal processes and properties of soils; elaboration of scientific and methodical bases of contaminated soils monitoring (diagnosis, assessment, forecast ecological state), environmental regulation of organic nature contaminants in soils; regulation of the using and soil remediation processes to improve quality. Based on the analysis of the scientific literature data and results of long-term experiments it was determined the optimal temperature range of 280–500 ○C with different temperature ranges of thermal evaporation the fractions of petroleum hydrocarbons. Series conducted modeling experiments with varying temperature, time, sample the soils and the changing quantitative and qualitative composition of hydrocarbons in contaminated soils, the total petroleum hydrocarbons thermogravimetric method has been found that the thermal degradation of contaminated soils samples formed various fractions of hydrocarbons, which leads to increased losses mass Dm contaminated soil sample to obtain thermogravimetric curves. By the method of gas chromatography, in the range of 100–200 ○C it is set the selective extraction of lighter fractions of petroleum and petroleum products in the soil; in the range of 280–350 ○C – it is noted a sharp increase in the rate of decomposition of oil saturated hydrocarbons (C10–C40) with intensive gas evolution, the formation of a mixture of reaction products is a significant amount of unsaturated hydrocarbons. Thus, the use of established ranges of determining the optimum temperature desorption fractions of petroleum hydrocarbons and their thermal degradation of soil samples for thermolysis with simultaneous identification of the total content of oil and petroleum products in the soil, it is possible to determine the total amount of oil hydrocarbons fractions in soil as the amount of oil hydrocarbons. The proposed algorithm method is suitable for the soils of different genesis. It is determined that the consistent increase in temperature is a necessary procedure for the identification of pollution if soil sample analysis of the expected low concentrations of oil and petroleum products and water content in soils of different types and different size distribution of more than 5 % of oil production zones. By evaluating the flow of thermal processes in the surveyed contaminated and uncontaminated soil samples the temperature ranges degradation of petroleum hydrocarbons is determined. Their using, as an indicator, significantly reduced the timing of selection of optimal technological parameters of thermal oils in the soils for determining the total content of oil and petroleum products in the soils, pollution monitoring and remediation efficiency control.

Enhanced biodegradation of aged petroleum hydrocarbons in soils by glucose addition in microbial fuel cells

AbstractBACKGROUNDBioelectrochemical remediation of soils contaminated by petroleum hydrocarbons has received increasing attention as an effective approach to remove pollution with simultaneous electricity generation.RESULTSHere, glucose was added as a co‐substrate in this system. The charge output of soil microbial fuel cells (MFCs) was enhanced by 262%, and the total petroleum hydrocarbon degradation rate increased by 200%. According to the increased dehydrogenase and polyphenol oxidase activities, the exogenetic glucose substantially activated hydrocarbon degradation bacteria (such as Alcanivorax). The Shannon–Wiener Index and richness of soil microbial community decreased after glucose addition, indicating that a selective enrichment of specific communities was imposed by glucose. Correlation analysis showed the biodiversity in soil far from the cathode was mainly determined by the concentration of petroleum hydrocarbons, while that in soil close to the cathode was dominated by the current.CONCLUSIONThis study demonstrated that an exogenetic carbon source enhanced the bioelectrochemically assisted degradation of aged petroleum hydrocarbons in saline soils, providing an effective approach to remove contaminations from soil in barren areas or extreme environments. © 2015 Society of Chemical Industry

Assessment of the Hydrocarbon Degrading Abilities of Three Bioaugmentation Agents for the Bioremediation of Crude Oil Tank Bottom Sludge Contaminated Libyan Soil

Bioremediation is a widely used environmental friendly treatment method for petrogenic hydrocarbon contaminated soils but its application to the treatment of crude oil tank bottom sludge (COTBS) contaminated soil is limited especially in Mediterranean countries such as Libya. Therefore in this study, the hydrocarbon degrading abilities of three bioaugmentation agents Pseudomonas sp (4M12), Pseudomonas xanthomarina (4M14) and Arthrobacter nitroguajacolicus (1B16A) (isolated from COTBS polluted soils) applied as part of a biostimulation-bioaugmentation (BS/BA) strategy were assessed in COTBS contaminated Libyan soils. Biostimulated (BS) and natural attenuation (NA) microcosms were also set up for comparative purposes. Gas chromatograph mass spectrometer (GC- MS) analysis revealed a total soil petroleum hydrocarbon (TPH) and polycyclic aromatic hydrocarbon (PAHs) content of 30,703 mg kg-1 and 13,816 mg kg-1 respectively. Two carcinogenic fractions (naphthalene and benzenamine, 4, 4`methylenbis [2-methyl-]) and 4 mutagenic fractions (pyrene, phenanthrene, fluorene and anthracene) were detected. Substantial PAH degradation occurred in 4M14 and 4M12 samples within 15 days in contrast to up to 23 days in 1B16A, NA. However, substantial reduction in TPH (> 97%) was only observed in 4M12 and 4M14 inoculated microcosms within 15 days compared to 25-30 days in 1B16A inoculated, BS and NA microcosms. 4M14 inoculated microcosms were most efficient at complete removal (D100) of all carcinogenic and mutagenic fractions; 4M14 (9-10 days), 4M12 (9-15 days), 1B16A (15-23 days), BS (18-21 days) and NA (18-22 days). Pseudomonas xanthomarina was therefore shown as the best candidate for use in a BS/BA approach for treating COTBS contaminated Libyan soils. This study shows the importance of pre-screening bioaugmentation agents for the removal of carcinogenic and mutagenic fractions prior to use; in order to carry out safe, efficient and sustainable COTBS bioremediation in Libya.

Bioremediation of Three Brazilian Soils Contaminated with Used Lubricating Oil

Objectives: This study aimed at bioremediation potentials of organic pollutants, in particular, used lubricating oil contaminated soils, using commercial microbial nutrient. Other objectives were the evaluation of kinetic model to determine the rate of biodegradation of petroleum hydrocarbon in soil and to subsequently determine the half-life of the oil degradation. Materials and Methods: The patterns of biodegradation of used motor oil were studied for a period of 90 days under laboratory condition. The model soil (300 g) was contaminated with 1.5% (w/w) of used motor oil at room temperature in the laboratory using microcosm of 1 L. The microcosm was used to simulate the comparative effect of used lubricating oil addition and bioremediation using a commercially available hydrocarbon degrading microbial consortium - Amnite P1300 as

Evaluation of Enzyme Expression in a Macrophytic Treated Crude Oil Soil Habitat: Implication for Enhanced Phytoremediation Potential Using Transgenic Botanicals

Background: Several studies have demonstrated the success of phytoremediation and its advantages over conventional physical and biochemical (even engineered transgenics) methods, resulting in its use on many contaminated sites. A direct method for enhancing the effectiveness of phytoremediation is to over express the genes in transgenic plants that are involved in metabolism, uptake and/or transport of specific pollutants. Objective: A screen-house ecological study was carried out to evaluate the remediation potentials of three species of the Fabaceae Family (Peltophorum pterocarpum, Leucaena leucocephala and Crotolaria retusa) for cleaning up soils contaminated with crude oil petroleum hydrocarbons. Result: Enzymatic analysis and hydrocarbon index assessment of the species and the vegetated and non-vegetated soils showed that P. pterocarpum recorded significant (p<0.05) performance over C. retusa and L. leucocephala in the uptake of hydrocarbons (oil and Grease (OG), Total Hydrocarbon Content (THC), organic carbon and organic matter content]. Results showed significant (p<0.05) reduction in enzyme expression and soil hydrocarbon index. C. retusa recorded significant (p<0.05) increase over P. pterocarpum and L. leucocephala in enzyme expression and reduction in foliar hydrocarbon index, with significant (p<0.05) increase in soil hydrocarbon index. Conclusion: Crotolaria retusa can thus be recommended as an integral component of any bioremediation technology package for hydrocarbon polluted terrestrial environment and by it transgenic enhancement of indigenous enzymes.

Baseline for PAHs and metals in NW Gulf of Mexico related to the Deepwater Horizon oil spill

As a rapid response to the massive oil spill caused by the sinking of the Deepwater Horizon (DWH) Platform in the northern Gulf of Mexico in April 2010, a baseline study was initiated. The study focused on determining the concentration of crude oil petroleum hydrocarbons and trace metals (Cr, Ni and V) in water and surface sediments from Mexico's EZZ, in the NW Gulf of Mexico. A total of 60 samples obtained from the shelf-slope regions were analyzed by GC/FID for 16 EPA priority polycyclic aromatic hydrocarbons (PAHs) and ICP/MS for Cr, Ni and V. The concentrations of PAHs in the surface water were below detection limits (<0.003–0.03 μg L−1) while in sediments, ranged from 0.01 to 0.070 μg g−1. International sedimentary quality guidelines (ERL-ERM) indicated a low probability of harmful effects to benthic organisms. Similarly, metal concentrations in sediments exhibited low concentrations (Cr 25.2–117, Ni 9.6–50.8, V 42.9–150.8 μg g−1). These metals were traced to a lithogenic source related to the heavy sediment load contributed by local rivers; no traces of anthropogenic inputs from oil related operations were identified. Significant enrichment of Ni and V was recorded in deep sediments whose ERL limits did not represent adverse conditions to benthic communities except for few sites on the upper continental slope. During the first two years of environmental monitoring of Mexico's EZZ in the NW Gulf of Mexico, no evidence of the DWH oil spill have been detected.