Diesel Contamination Research Articles

Assessment of bimetallic Zn/Fe0 nanoparticles stabilized Tween-80 and rhamnolipid foams for the remediation of diesel contaminated clay soil

Diesel contamination of soil due to oil spills, disposal of refinery waste, oil exploration constitutes a major environmental problem. This paper reports the remediation of diesel contaminated clay soil using Zn/Fe0 bimetallic nanoparticle stabilized Rhamnolipid (RMLP) and Tween-80 (TW-80) surfactant foams. Fe0, and Zn (x wt%)/Fe0 (x = 0.2, 2.0, and 10.0) bimetallic nanoparticles are synthesized by using sodium borohydride reduction method. The average particle size (from FESEM) is calculated to be 62, 57, 42 and 35 nm for the Fe0, Zn (0.2)/Fe0, Zn (2)/Fe0 and Zn (10)/Fe0 nanopowders, respectively. The highest foamability and foam stability of 109.6 and 108.5 mL, respectively are observed for the RMLP (12 mg/l) surfactant foam stabilized with 6 mg/l Zn (10)/Fe0 nanoparticles. The surface tension values reduce to the lowest value of 28.1 and 31.4 mN/m with the addition of 6 mg/l of Zn (10)/Fe0 powder in RMLP and TW-80 solutions of 12 mg/l, respectively. The maximum diesel removal efficiency of 83.8 and 59%, is achieved by RMLP (12 mg/l) foam stabilized by Zn (10)/Fe0 nanoparticles (6 mg/l) for the clay soil contaminated with 100 and 500 μl/g of diesel, respectively. The physicochemical properties of the nanoparticles are studied to explain the foam properties and the remediation behavior. These findings regarding the nanoparticle stabilized foams can offer a cost-effective environment friendly commercial solution for soil remediation in the future.

Bioremediation of hydrocarbon contaminated soil using local organic materials and earthworms

Bioremediation technologies have demonstrated significant success on biological quality recovery of hydrocarbon contaminated soils, employing techniques among which composting and vermiremediation stand out. The aim of this study was to evaluate the efficiency of these processes to remediate diesel-contaminated soil, employing local organic materials and earthworms. During the initial composting stage (75 days), the substrate was made up using contaminated soil, lombricompost, rice hulls and wheat stubbles (60:20:15:5% w/w). Diesel concentration in the contaminated substrate was about 5 g kg−1, equivalent to a Total Petroleum Hidrocarbons (TPH) experimental concentration of 3425 ± 50 mg kg−1. During the later vermiremediation stage (60 days), the earthworm species Eisenia fetida and Amynthas morrisi were evaluated for their hydrocarbon degradation capacity. Physicochemical and biological assays were measured at different times of each stage and ecotoxicity assays were performed at the end of the experiments. TPH concentration reduced 10.91% after composting and from 45.2 to 60.81% in the different treatments after vermiremediation. Compared with TPH degradation in the treatment without earthworms (16.05%), results indicate that earthworms, along with indigenous microorganisms, accelerate the remediation process. Vermiremediation treatments did not present phytotoxicity and reflected high substrate maturity values (>80% Germination Index) although toxic effects were observed due to E. fetida and A morrisi exposure to diesel. Vermiremediation was an efficient technology for the recovery of substrate biological quality after diesel contamination in a short period. The addition of organic materials and suitable food sources aided earthworm subsistence, promoted the decontamination process and improved the substrate quality for future productive applications.

Effects of diesel contamination on geotechnical properties of granitic residual soil

Effects of diesel contamination on geotechnical properties of granitic residual soil

Phytoremediation of diesel contaminated soil using urban wastewater and its effect on soil concentration and plant growth

Abstract To assess the ability of tall fescue (Festuca arundinacea) and grass pea (Lathyrus sativus) plant species to effect phytoremediation with the utilization of freshwater and urban wastewater, greenhouse experiments were conducted in 2018 and 2019 with three levels of diesel contamination of 0, 1.5, and 3% w/w (referred to as DC (clean soil), D1.5 and D3, respectively). The maximum soil diesel content removal for tall fescue was by freshwater (54% (2018); 46% (2019)) and in the grass, the pea was by wastewater (44% (2018); 41% (2019)). A significant difference was observed in the amount of diesel removal by the plants at two levels of contamination, but the type of irrigation water had no significant effect. The plant growth decreased significantly by increased diesel in all treatments except D1.5 for tall fescue (2018) that led to better growth compared to the DC treatment. Diesel concentration had significant effects on plant parameters (dry weight, height, color, time of flowering, and podding), but the type of water had no similar impact. Phytoremediation was considered an effective method to reduce soil contamination, but treated wastewater could not significantly improve phytoremediation performance. The correlation coefficient indicated that the diesel removal rate was positively correlated with plant height and shoot dry weight (p < 0.01).

Impact of diesel and detergent contamination on gasoline low-speed pre-ignition and their characterization using unwashed gums

Fuel composition variability affects many aspects of engine operation. This includes the propensity to trigger abnormal combustions. Fuel logistic can lead to incorporating different contaminants into gasoline. Diesel fuel or over-concentrated detergent additives are two examples. They require a qualification and quantification within the gasoline fuel and an evaluation of their impact on engine performances.We consider both contaminants in this work and it addresses simultaneously their identification within a gasoline fuel and their impact on abnormal combustion. The study evaluates contaminants propensity to trigger Low Speed Pre-Ignition (LSPI). The latter is a stochastic abnormal combustion leading to engine damage related to fuel quality. A novel method based on unwashed gums is used to characterize qualitatively and quantitatively these contaminants. Engine tests led to the conclusion that diesel contamination contributes to increase LSPI frequency and severity. However, this increase depends on the base fuel heavy aromatic content. Deposit control additive (DCA) increases slightly LSPI frequency compared to diesel contaminant. The study also suggests that such additive can contribute to recover a less sensitive combustion system once it has been running with a diesel contaminated gasoline. Finally, this work explores the possibility of correlating fuel propensity to trigger LSPI through unwashed gums (UWG) measurement. It concludes that the approach seems sensible but requires further work to be confirmed.

Induced systemic tolerance mediated by plant-microbe interaction in maize (Zea mays L.) plants under hydrocarbon contamination

The present investigation was committed to examining the effect of soil spiked with diesel contamination (0, 1.5, 2.5, 3.5 g diesel kg−1 soil) on maize (Zea mays L) varieties (MMRI yellow and Pearl white) with or without bacterial consortium (Pseudomonas aeruginosa BRRI54, Acinetobacter sp. strain BRSI56, Acinetobacter sp. strain ACRH80). Seed and soil bacterial inoculation were done. The studied morphological attributes were fresh and dry weight of shoot and root of both maize varieties. The results documented that bacterial consortium caused 21%, 0.06% and 29%, 34% higher shoot and root fresh/dry weights in “Pearl white” and 14%, 15% and 32%, 22% shoot and root fresh/dry weights respectively in MMRI yellow under control conditions. The biochemical attributes of shoot and root were affected negatively by the 3.5 g diesel kg−1 soil contamination. Bacterial consortium enhanced enzymatic activity (APX, CAT, POD, SOD, GR) and non-enzymatic (AsA, GSH, Pro, α-Toco) antioxidant and reduction in oxidative stress (H2O2, MDA) under hydrocarbon stress as compared to non-inoculated ones in both root and shoot organs. Among both varieties, the highest hydrocarbon removal (75, 64, and 69%) was demonstrated by MMRI yellow with bacterial consortium as compare to Pearl white showed 73, 57, 65% hydrocarbon degradation at 1.5 2.5, 3.5 g diesel kg−1 soil contamination. Consequently, the microbe mediated biotransformation of hydrocarbons suggested that the use of PGPB would be the most beneficial selection in diesel fuel contaminated soil to overcome the abiotic stress in plants and successfully remediation of hydrocarbon in contaminated soil.

Combined Application of Ozone and Hydrogen Peroxide to Degrade Diesel Contaminants in Soil and Groundwater

Environmental pollution has been a major concern in recent times, and soil and groundwater pollution are areas which have received particular focus. This has led to the development of various remediation techniques such as excavation, soil vapor extraction, bioremediation, chemical oxidation, and so on. Among all remediation techniques, chemical oxidation has been proven to be the most effective and feasible technique around the world. In this study, various combinations of ozone and hydrogen peroxide were used to treat diesel-contaminated soil and groundwater in an experimental setup. Experimental soil and groundwater were prepared with properties similar to the contaminated soil. An ozone generator and a pump injection system were deployed for combining ozone and hydrogen peroxide. Five different experiment batches were prepared based on the hydrogen peroxide concentration and its ratio to the soil. The diesel concentration in the water dropped from 300 mg/L to 7 mg/L in the first hour of treatment, which dropped below the detection limit (0.01 mg/L) thereafter. Similarly, 63.9% degradation was achieved with the combined sparging of ozone and hydrogen peroxide in the soil. Ozone combined with 7% hydrogen peroxide was the most promising combination for removing the contaminants. In addition, this research explored the hydroxyl radical conversion rate of ozone and the perozone, the difference in order of magnitude is greater than one which shows that the perozone has better oxidation capacity than ozone only. The findings of this study show that combining ozone with hydrogen peroxide is a competent and feasible onsite remediation method for diesel contaminants in soil and groundwater. Thus, this method can be applied in local gas stations, accidental spillage sites, and small-scale refineries for onsite treatment in a cost-effective and technically sound way within a short time span.

Optimum conditions of zero-valent iron nanoparticle stabilized foam application for diesel-contaminated soil remediation involving three major soil types

Stability of foam, enhanced by nano zero-valent iron (nZVI) and its optimized constituents, may have significant potential for effective treatment of soil contaminated with diesel oil-a major environmental problem. The optimum diesel removal efficiency from distinct types of soil accomplished by the unique application of such foams as well as the optimum conditions of the foaming constituents have not been reported in literature so far. Hence, in this work, the removal of diesel contaminant from different soil types (desert, coastal, clay soil) is optimized, and the optimized results are reported for the first time, using response surface methodology (RSM), for alkylpolyglucoside phosphate (APG-Ph) foam, stabilized by nZVI. The effect of concentrations of APG-Ph (0.02, 0.04, 0.06, 0.08, and 0.1 volume %) and nZVI (2, 3, and 3.5mg/l) on diesel removal efficacy from soil is studied using Box-Behnken design (BBD) of response surface methodology (RSM). Maximum diesel removal efficiency obtained at a concentration of 0.1 volume % APG-Ph foam with 3.5mg/l nZVI for desert, coastal, and clay soil is 94.6, 95.3, and 57.5%, respectively. The optimum concentrations of APG-Ph and nZVI are found to be 0.98 volume % and 0.8mg/l, respectively. Validation of this optimal condition experimentally results in highest removal efficiency of 98.3, 97.2, and 75.9% for desert, coastal, and clay soil respectively. This is in good agreement with the predicted values by RSM (98.67, 97.57, and 76.85%). The maximum diesel removal efficiency predicted at optimal concentration of APG-Ph and nZVI is significantly larger than the results reported in literature in last three years.

Mangrove’s rhizospheric engineering with bacterial inoculation improve degradation of diesel contamination

Mangroves (Avicennia marina) growing in intertidal areas are often exposed to diesel spills, adversely damaging the ecosystem. Herein, we showed for the first time that mangrove seedlings’ associations with bacteria could reprogram host-growth, physiology, and ability to degrade diesel. We found four bacterial strains [Sphingomonas sp.-LK11, Rhodococcus corynebacterioides-NZ1, Bacillus subtilis-EP1 Bacillus safensis-SH10] exhibiting significant growth during diesel degradation (2% and 5%, v/v) and higher expression of alkane monooxygenase compared to control. This is in synergy with reduced long-chain n-alkanes (C24-C30) during microbe-diesel interactions in the bioreactor. Among individual strains, SH10 exhibited significantly higher potential to improve mangrove seedling’s morphology, anatomy and growth during diesel treatment in rhizosphere compared to control. This was also evidenced by reduced activities and gene expression of antioxidant enzymes (catalases, peroxidases, ascorbic peroxidases, superoxide dismutases and polyphenol peroxidases) and lipid peroxidation during microbe-diesel interactions. Interestingly, we noticed significantly higher soil-enzyme activities (phosphatases and glucosidases) and essential metabolites in seedling’s rhizosphere after bacteria and diesel treatments. Degradation of longer n-alkane chains in the rhizosphere also revealed a potential pathway that benefits mangroves by bacterial strains during diesel contaminations. Current results support microbes' application to rhizoengineer plant growth, responses, and phytoextraction abilities in environments contaminated with diesel spills. Availability of data and materialsThe datasets generated during the current study are available in the NCBI GenBank ((https://www.ncbi.nlm.nih.gov).

Nutrient status, hydrogen peroxide content and peroxidase activity of arbuscular mycorrhizal plants of Melilotus albus grown in diesel-contaminated substrate

Background: Petroleum hydrocarbons affect plant growth, but little is known about physiological responses of mycorrhizal plants facing diesel contamination.
 Objective: To evaluate the effects of arbuscular mycorrhizal fungi (AMF) on the nutritional status, peroxidase activity (POX), and hydrogen peroxide content (H2O2) in leaves of Melilotus albus planted under diesel-contaminated sand (7500 mg kg-1).
 Methods: A 2x2 factorial experiment was set in a completely randomized design, under greenhouse conditions for 35 days. Seedlings were pre-inoculated with AMF and transplanted to sand with or without diesel, including non-AMF plants.
 Results and conclusions: Diesel contamination impaired plant growth; AMF plants had similar growth than non-AMF plants at diesel-contamination, but low nutrient content. Protein content decreased due to diesel in non-AMF plants, but this content was low in AMF plants regardless diesel contamination. Diesel increased POX; whereas AMF plants with or without diesel had higher POX than non-AMF plants. The H2O2 content in AMF plants with or without diesel was low than non-AMF plants. Diesel contamination diminished AMF-colonization, but AMF dissipate more diesel hydrocarbons (>40%). Overall, AMF alleviated the toxic effects of diesel on plants.

Geotechnical Evaluation of Diesel Contaminated Clayey Soil

Soil contamination by different hydrocarbons has rapidly expanded worldwide, surpassing the self-purification capacity of soils and increasing the number of contaminated sites. Although much effort has been devoted to study the effects of diesel contamination on the geotechnical properties of soil, there is still limited available information about it. Moreover, there is no available information about the maximum diesel retention that soil can have and its effect on the geotechnical behavior of the soil. Thus, in this paper, we determined the maximum diesel retention by an unsaturated clayey soil and evaluated the impact of diesel contamination on its geotechnical properties. The results showed that the soil could only retain 12.6% of the added diesel and the excess was expulsed. At such a diesel concentration, the saturation rate of the soil was lower than 80%. Diesel contamination increased the plasticity and the internal friction angle of the soil, while its cohesion was considerably decreased. It should be noted that the matric suction of contaminated soil was lower than the one obtained for natural soil. However, its osmotic suction was considerably higher. This indicates that osmotic suction must be considered to evaluate the shear strength of contaminated soils.

Foam flushing with soil vapor extraction for enhanced treatment of diesel contaminated soils in a one-dimensional column

A limitation of soil vapor extraction (SVE) remediation for total petroleum hydrocarbons (TPHs) in the unsaturated zone is the inability to remove the less volatile petroleum mixture compounds in diesel fuel. SVE combined with foam flushing may have the potential to enhance dissolution or mobilization of soil sorbed diesel and allow mobilized diesel to move to the SVE extraction well. A nonionic surfactant polyoxyethylene (20) sorbitan monooleate (TW80) was selected for generating foam, and a procedure to incorporate the oxidant sodium persulfate (SPS) in generating TW80/SPS foam to deliver chemical oxidation, was also studied. Both TW80 and TW80/SPS foams exhibited 96–98% quality under 8–32 mM of TW80 and 10–50 mM of SPS. The addition of SPS in TW80 solution resulted in elevated ionic content and degradation of TW80, which may reduce the foam stability and have minor effects on foam quality. Through analysis of interrelationships among column flushing experimental parameters, it was shown that the foam quality was reduced to 42–47% when foam flushed through a diesel contaminated soil column. Moreover, the results of column flushing tests operated for 12 h indicated that the effectiveness of removal of diesel by different foams followed the order of TW80 foam (53%) > TW80/SPS foam (37%) >N2 gas flow alone (3%). It was shown that foam flushing could be an alternative approach, rather than using N2 gas flow alone (SVE), in enhancing SVE for reducing diesel contamination in the unsaturated zone.

The role of humic acid in Fenton reaction for the removal of aliphatic fraction of total petroleum hydrocarbons (diesel range) in soil

This study investigated the role of humic acid in Fenton reaction for the total petroleum hydrocarbons (TPH) (diesel) in soil. Batch reactions were conducted at varying humic acid dosages and pH. For the lowest molecular weight diesel contaminants, a humic acid dosage of 10 mg/l produced the favourable effect of reducing Fe3+ to Fe2+ which continued for higher humic acid dosages of 50, 100 and 150 mg/l. Conversely, for higher molecular weight diesel contaminants, the negative effect of hydroxyl radicals consumption by the humic acid was more significant than its reduction of Fe3+ to Fe2+. The positive role of humic acid on Fenton reaction increased with increasing humic acid dosage for the overall TPH, with an optimum dosage of 150 mg/l. At higher pH, the removal efficiencies increased or reduced depending on the molecular weight of TPH. The power law and pseudo-first-order kinetic models fitted the experimental kinetic data well.

Geophysical Assessment of Groundwater Vulnerability to Diesel Contamination at a Telecommunication Mast in Adebayo Area, Ado-Ekiti, Southwestern Nigeria

Abstract An appraisal of the groundwater vulnerability to contamination risk at Adebayo in Ado-Ekiti, Southwestern Nigeria, was carried out using the electrical resistivity method of geophysical prospecting. Two traverses of length 100 m each were established for both vertical electrical sounding (VES) and dipole-dipole. Six (6) Vertical Electrical Sounding (VES) and 2-D dipole-dipole profiling techniques of the electrical resistivity method were adopted for the geophysical investigation. The results show variations in resistivity values, depicting four to five geologic layers: the topsoil, laterite, weathered layer, fractured, and the fresh basement. It was observed from the correlation of the geoelectric section and 2-D resistivity image along traverse 1 (TR1) that the groundwater in the study area flows towards the southwestern part, and the fractured basement serves as a migration pathway to the diesel oil in the same direction as groundwater flow. The fractured basement (Well 2) with no lateritic cover has higher resistivity values compare to the fracture zone that was found directly under the mast which was overlain by the laterite. Comparing the resistivity values of Well 1 and 2, Well 2 that was drilled into the fractured basement has more traces of the contaminant than Well 1.

Geotechnical Properties and Microstructure of a Diesel Contaminated Lateritic Soil Treated with Lime

ABSTRACT Studies involving oil-contaminated lateritic fine-grained soils are still scarce in literature, especially regarding treatments for improving soils mechanical properties. In this study, geotechnical properties and microstructure of a diesel-contaminated lateritic soil treated with lime are investigated and compared to tests conducted on lime-treated soil (2% to 8% lime) and diesel-contaminated soil (2 to16% diesel). The presence of diesel had no significant effect on soil plasticity but decreased soil strength. Lime stabilization applied to diesel-contaminated soils significantly improved soil properties after 6% of lime stabilizer. The diesel presence led to an inhibition of lime reaction due to reduction of cation exchange capacity and flocculation, which reflected in loss of its effectiveness in improving strength as compared to natural soil response. The water retention behavior and unsaturated hydraulic conductivity of soil were affected by diesel contamination, leading to curve shapes similar to clay materials. Adding 2% of lime to the contaminated soil, increase in the soil pores and changes in the shapes of water retention curve and k-functions were observed with similar behavior of a course-grained material. Overall, this study highlights how the presence of diesel and lime affects lateritic soil properties and microstructure.

Diesel in Antarctica and a Bibliometric Study on Its Indigenous Microorganisms as Remediation Agent.

Diesel acts as a main energy source to complement human activities in Antarctica. However, the increased expedition in Antarctica has threatened the environment as well as its living organisms. While more efforts on the use of renewable energy are being done, most activities in Antarctica still depend heavily on the use of diesel. Diesel contaminants in their natural state are known to be persistent, complex and toxic. The low temperature in Antarctica worsens these issues, making pollutants more significantly toxic to their environment and indigenous organisms. A bibliometric analysis had demonstrated a gradual increase in the number of studies on the microbial hydrocarbon remediation in Antarctica over the year. It was also found that these studies were dominated by those that used bacteria as remediating agents, whereas very little focus was given on fungi and microalgae. This review presents a summary of the collective and past understanding to the current findings of Antarctic microbial enzymatic degradation of hydrocarbons as well as its genotypic adaptation to the extreme low temperature.

Experimental investigation into the effects of diesel dilution on engine lubrication

The dilution of lubricant due to contamination with diesel fuel is an increasingly prevalent, potentially important and poorly understood issue. This study addresses two fundamental questions: 1) How does the change in lubricant rheology due to diesel dilution affect engine lubrication? 2) How is the chemical performance of lubricant components (base oil and performance additives) impacted by diesel dilution under different lubrication regimes (boundary/full film, hydrodynamic/elastohydrodynamic). This is achieved by testing three lubricant samples: 1) neat fully formulated 0W-30 engine oil, 2) fully formulated 0W-30 oil diluted with diesel at a concentration of 15%, denoted “0W-30D”, and 3) neat, fully-formulated 0W-16, with the same base oil components and performance additives as the 0W-30, but blended to give a viscosity equal to that of the diluted an equivalent “0W-30D”. Tribometer tests, including 1) low pressure, low shear viscosity, 2) Ultra-high Shear Viscosity (USV), 3) elastohydrodynamic film thickness, 4) Stribeck friction and 5) boundary friction and wear, are then conducted. To further emulate engine lubrication conditions, Stribeck curve measurements are performed on the three lubricants using a journal bearing test rig, fitted with a connecting-rod and commercial diesel engine shells. Results suggest that diesel dilution only slightly affects chemical additive performance (with friction modifiers being more inhibited than anti-wear additives) but does reduce both viscosity and film thickness. However, care must be taken in using viscometrics to predict dilution behaviour because 1) the pressure viscosity coefficient is also affected by diesel dilution which has implications for elastohydrodynamically lubrication contacts, 2) shear thinning means that viscosity modifier additives effects lose their functions at high shear rates; whereas diesel contamination affects viscosity behaviour throughout the whole shear rate range.

Effect of Co-contamination by PAHs and Heavy Metals on Bacterial Communities of Diesel Contaminated Soils of South Shetland Islands, Antarctica.

Diesel oil is the main source of energy used in Antarctica. Since diesel is composed of toxic compounds such as polycyclic aromatic hydrocarbons (PAHs) and heavy metals, it represents a constant threat to the organisms inhabiting this continent. In the present study, we characterized the chemical and biological parameters of diesel-exposed soils obtained from King George Island in Antarctica. Contaminated soils present PAH concentrations 1000 times higher than non-exposed soils. Some contaminated soil samples also exhibited high concentrations of cadmium and lead. A 16S metagenome analysis revealed the effect of co-contamination on bacterial communities. An increase in the relative abundance of bacteria known as PAH degraders or metal resistant was determined in co-contaminated soils. Accordingly, the soil containing higher amounts of PAHs exhibited increased dehydrogenase activity than control soils, suggesting that the microorganisms present can metabolize diesel. The inhibitory effect on soil metabolism produced by cadmium was lower in diesel-contaminated soils. Moreover, diesel-contaminated soils contain higher amounts of cultivable heterotrophic, cadmium-tolerant, and PAH-degrading bacteria than control soils. Obtained results indicate that diesel contamination at King George island has affected microbial communities, favoring the presence of microorganisms capable of utilizing PAHs as a carbon source, even in the presence of heavy metals.

Deciphering the synergistic impact of elevated temperature and oil pollution on meiobenthic community structure: A benthocosm study

Meiobenthos has been considered as an excellent tool for biomonitoring assessment. Elevated temperature and oil pollution are considered as the most pervasive aspects of global environmental changes and matter of concern for contemporary society. Presently, very limited information is available about the synergistic effect of these stressors on meiobenthic community structure and tolerance potential from tropical intertidal environment. Here, we assessed their impacts on meiobenthic community by conducting a 60 days long benthocosm experiment selecting three sets of temperature (25°, 30° and 35 °C) and two sets of diesel oil (low and high) combinations. Gradual changes in their community composition were revealed discernibly with exposures to both the disturbances after 30 and 60 days of experimental period. Diversity profiles for the nematodes were less affected, but copepods showed a graded response of decreasing density with increasing dose of both the stressors. Other meiobenthic taxa such as halacarid mite, turbellaria and polycheate juveniles were adversely affected and eliminated from the treatments, howbeit abundance of ostracods, foraminiferans and bivalve settlers varied significantly. A 3-factor PERMANOVA indicated a significant effect of temperature, diesel, between their interaction and interaction among stressors and time on meiofaunal abundances. In case of free-living nematodes, temperature rise and diesel contamination synchronously led to an elimination of k-selected species like Halalaimus gracilis, H. longicaudatus, Oxystomina aesetosa and Pomponema sp. with a significant decrease in abundance of H. capitulatus and Oncholaimus sp. The r-selected species Daptonema invagiferoum, Sabatieria praedatrix, Theristus acer, Monhystera sp. and Thalassomonhystera sp. had endured even at high doses of diesel treatment in three different temperatures set up. The effects were evident in term of changes in life strategies with an increment of opportunistic species and increased trophic diversity of deposit feeders in treated sediments. Overall, elevated temperature together with diesel oil contamination were found to alter species dynamics within shallow intertidal meiobenthic communities, which might have significant Armageddon on benthic ecosystem functioning.

Survival Response of Consortium Isolates from Diesel Contaminated Soil within Katsina State, Nigeria

Environmental increase in the spilled diesel creates serious damages to our natural ecosystems. Biodegradation provide the best removal alternative for such diesel contamination. This study was carried out to monitor the bacteria survival response during diesel oil biodegradation. Bacteria isolation was carried out using plating technique and screened at varying diesel concentrations (0 to 10%, v/v) before being identified using the 16S rRNA gene sequencing. Bacteria consortia were formulated using the screened isolates through mathematical permutation approach. Prepared bacteria resting cells of the selected consortium was grown at 2%, v/v diesel oil which was co-contaminated with varying concentrations of Mg++, Mn++, Zn+, Co++ and Fe++ (0 to 4 g/L) in mineral salts medium. Total of 47 different bacteria strains were isolated and the finally screened isolates were identified as Alcaligenes sp., Ochrobactrum sp., Alcaligenes aquatilis and Alcaligenes faecalis UMYU001 (MN519483.1). These bacteria were found to be compatible with one another despite being obtained from different environments. Of the prepared consortia, combination 11 (CST11) was found to produce the highest population of 1.6 x 104 cfu/mL after 48 hours at 2% v/v diesel oil. This CST11 survived optimally at 35°C, 7.0, and 2% v/v of the temperature, pH and diesel oil respectively. Also, the resistance thresholds of the metals for CST11 include Mg++ (3.5 g/L) while Mn++, Zn++, Co++ and Fe++ were only resisted at 1 g/L. This recommends the consortium as good enough in surviving at the sole expense of diesel oil even in the presence of heavy metals co-contaminants.