Petroleum Hydrocarbon Concentrations Research Articles

Integrated geophysical and geochemical methods for environmental assessment of subsurface hydrocarbon contamination.

Oil spills have become a major source of environmental pollution in Nigeria, especially in the oil-producing communities. Assessment of hydrocarbon contamination within the subsurface is a complex program and requires both field-based measurement and geochemical analysis, to give a precise definition of the extent of pollution. To ascertain the extent of contamination of the subsurface around an oil spill site which was reportedly contaminated by oil pollution, an integrated geophysical method involving 1D vertical electrical sounding (VES) and 2D, 3D electrical resistivity tomography (ERT) techniques supported with geochemical method was employed. Orthogonal set of 2D resistivity data consisting of six (6) parallel and six (6) perpendicular profiles were acquired in a 100 × 50-m2 rectangular grid using the Wenner array. Ten (10) vertical electrical soundings were also acquired in the site to supplement the 2D profiles. 2D resistivity data were processed individually using 2D Earth Imager software. The entire set of 2D resistivity data is collated into a 3D dataset using a 3D collation code and was inverted to produce a 3D resistivity structure of the subsurface, following from which contaminant plumes with high resistivity anomalies due to oil pollution were observed from 2D and 3D resistivity images. 2D resistivity tomography imaged contaminant plume to depth of 17.1 m, while 3D resistivity tomography imaged plumes of hydrocarbon contaminant to depth of 19.8 m within the subsurface. 3D depth slices imaged hydrocarbon contaminants within the third, fourth, and fifth layers at depths of 5.38-8.68 m, 8.68-12.5 m, and 12.5-16.9 m respectively. Thus, hydrocarbon contamination was evidently increasing with depth as observed in VES survey which indicated pollution to depth beyond 24 m, which goes beyond the depth to first and second aquifers in the area, indicating that the first and second aquifers have been invaded by oil pollution. Similarly, geochemical analysis of groundwater samples from three boreholes showed average concentration of total petroleum hydrocarbon (TPH) as 722.75µg/L which is higher than DPR limits indicating high contamination. Poly aromatic hydrocarbons (PAHs) concentration in the samples was summed up to 0.66µg/L in BH1, 0.68µg/L in BH2, and 0.30µg/L in BH3, which are above the DPR target limit. BTEX compounds also showed elevated concentrations in the water samples. These findings validate the result of geophysical investigation; therefore, future research should aim to proffer remediation solutions to oil spill impact on the environment within the study area. The findings of this study can help for better understanding of the subject of electrical resistivity inversion, and particularly on 3D inversion technique for delineating subsurface plumes of hydrocarbon contamination.

Simulating diluted bitumen spills in boreal lake limnocorrals - Part 1: Experimental design and responses of hydrocarbons, metals, and water quality parameters

Large-scale, in-lake enclosures (limnocorrals) were used to simulate spills of diluted bitumen (dilbit) in a boreal lake. In this study we use these simulated spills, which covered a range of sizes (oil:water ratio) representative of the upper 25% of onshore crude oil spills in North America (2008–2019), to assess the fate of dilbit-derived hydrocarbons and metals as well as the impacts of the spills on standard water quality parameters. The systems were monitored over 70 days following the application of dilbit amounts ranging between 1.5 and 179.8 L into 10-m diameter, ~100 m3 limnocorrals. The concentration of total petroleum hydrocarbons (TPH) in the water column increased rapidly over the first two weeks reaching a plateau that ranged between 200 μg/L and 2200 μg/L for the lowest and highest treatment respectively. The concentration of total polycyclic aromatic compounds (PACs) also increased over the first two weeks, prior to a slow decrease until day 70. The maximum measured concentrations in the highest treatment were 2858 ng/L for the sum of all 46 quantified PACs, 2716 ng/L for alkylated PACs and 154 ng/L for the 16 EPA priority PAHs. The concentrations of PACs in the sediment increased continuously over the study in the three highest treatments with maximum observed concentrations of 189 ng/g for ΣPAC46, 169 ng/g for ΣPACalk. No significant treatment-related changes in the 16 EPA priority PAHs were observed in the sediment. Of the 25 metals quantified in the water column, only manganese, molybdenum, and vanadium displayed a significant treatment effect with increases of 280, 76 and 25% respectively in the total fraction. These results can help us understand and predict the fate of oil-derived contaminants following a spill and characterize the exposure of freshwater organisms living within them. These results should help inform the risk assessment of future dilbit transportation projects.

Ecological criteria for assessing the content of petroleum hydrocarbons in the main soils of coniferous-deciduous forests and forest steppe.

The effect of pollution of Albicluvisols/Retisols, Calcaric Leptosols, Luvic Phaeozems, Greyzamic Phaeozems and Folic Fluvisols with oil (Solovatovsky oil field, Perm region) added in amounts of 1, 2, 3 and 5g oil/kg of soil on the organisms was studied in a model laboratory experiment. Oil addition showed phytotoxic effects on root length in Triticum aestivum L., Lepidium sativum L., Picea obovata Ledeb. and Pinus sylvestris L. in all soils. However, oil contamination of Calcaric Leptosols and Greyzamic Phaeozems led to growth stimulation in Picea obovata seedlings. A remarkable shift in the diversity and number of colony-forming units of heterotrophic and oil-oxidizing bacteria was detected in all soil types. The maximum decrease in biodiversity (45%) was noted for heterotrophic bacteria in Luvic Phaeozems. Aqueous extracts from all oil-contaminated soils had a toxic effect on Chlorella vulgaris Beijer, causing an increase in biomass by more than 30%, but did not show acute toxicity on Daphnia magna Straus. Oil addition in the range of 1-3g oil/kg soil posed no environmental risk to human health. However, oil addition at 5g oil/kg of soil led to an increase in the level of carcinogenic risk to children to the threshold values of acceptable risk and ranged from 0.95 × 10-4 for Greyzamic Phaeozems and Folic Fluvisols to 1.098 × 10-4 for Luvic Phaeozems. Our results suggest that the reaction of test organisms to oil pollution depends on the soil type, and their complex application makes it possible to identify the most sensitive factor and assess the dangerous level of pollution.

A New Ciboria sp. for Soil Mycoremediation and the Bacterial Contribution to the Depletion of Total Petroleum Hydrocarbons.

A Ciboria sp. strain (Phylum Ascomycota) was isolated from hydrocarbon-polluted soil of an abandoned oil refinery in Italy. The strain was able to utilize diesel oil as a sole carbon source for growth. Laboratory-scale experiments were designed to evaluate the use of this fungal strain for treatment of the polluted soil. The concentration of total petroleum hydrocarbons (TPH) in the soil was 8,538 mg/kg. Mesocosms containing the contaminated soil were inoculated with the fungal strain at 1 or 7%, on a fresh weight base ratio. After 90 days of incubation, the depletion of TPH contamination was of 78% with the 1% inoculant, and 99% with the 7% inoculant. 16S rDNA and ITS metabarcoding of the bacterial and fungal communities was performed in order to evaluate the potential synergism between fungi and bacteria in the bioremediation process. The functional metagenomic prediction indicated Arthrobacter, Dietzia, Brachybacerium, Brevibacterium, Gordonia, Leucobacter, Lysobacter, and Agrobacterium spp. as generalist saprophytes, essential for the onset of hydrocarbonoclastic specialist bacterial species, identified as Streptomyces, Nocardoides, Pseudonocardia, Solirubrobacter, Parvibaculum, Rhodanobacter, Luteiomonas, Planomicrobium, and Bacillus spp., involved in the TPH depletion. The fungal metabolism accelerated the onset of specialist over generalist bacteria. The capacity of the Ciboria sp. to deplete TPH in the soil in treatment was also ascertained.

Bioremediation of clay with high oil content and biological response after restoration

The clay with high oil content form soil lumps, which is hard for microbes to repair. In this paper, the bioaugmentation and biostimulation technology were applied to improve the bioremediation effect of the soil with high oil content, that modified by local cow dung and sandy soil, the ecological toxicity of the soil after restoration was further analyzed. After 53 days of bioremediation, the degradation efficiency with respect to the total petroleum hydrocarbons (TPH) content reached 76.9% ± 2.2%. The soil bacterial count of M5 group reached log10 CFU/g soil = 7.69 ± 0.03 and the results were better than other experimental groups. The relative abundances of petroleum-degrading bacteria added to M5 remained high (Achromobacter 9.44%, Pseudomonas 31.06%, and Acinetobacter 14.11%), and the proportions of some other indigenous bacteria (Alcanivorax and Paenibacillus) also increased. The toxicity of the bioremediated soil was reduced by seed germination and earthworm survival experiments.

Petroleum hydrocarbon concentrations in the surface sediments of two major sea ports, Bay of Bengal, India

Petroleum hydrocarbon concentrations in the surface sediments of two major sea ports, Bay of Bengal, India

Environmental and socioeconomic impacts of pipeline transport interdiction in Niger Delta, Nigeria

Over the years, pipelines have been the most economic medium for transporting crude oil to production and distribution facilities in the Niger Delta area of Nigeria. However, damages to the pipelines in this area by interdiction have hampered the continuous flow of crude oil to the facilities. Consequently, the revenue of the government dwindles, and the environment is severely degraded. This study assesses the economic and environmental impacts of pipeline interdiction in the Niger Delta region. Data from National oil spills detection and response agency, Nigeria is used to map spatial distribution of oil spills using Kernel Density Estimation with Geographic Information System. Literature was assessed to synthesize the historical, socioeconomic, and environmental impacts of oil spills and pipeline interdiction. Soil samples were collected from study area to determine the types of hydrocarbon pollutants and their concentrations in comparison with uncontaminated sites in the area. Results show that the range of concentrations of total petroleum hydrocarbon (TPH) for the impacted soil (IMP) was 17.27–58.36 mg/kg; remediated soil (RS) was 11.73–50.78 mg/kg which were higher than the concentrations of 0.68 mg/kg in the control samples (CS). Polycyclic aromatic hydrocarbons (PAH) concentrations were in the range of 0.43–77.54 mg/kg for IMP, 0.42–10.65 mg/kg for RS, against CS value of 0.49 mg/kg while BTEX ranged between 0.02 – 0.38 mg/kg for IMP, 0.01–2.7 for RS against CS value of 0.01. The values of the PAH were higher than the limits of the Department of Petroleum Resources, Nigeria. This study also revealed that pipeline interdiction has affected the livelihood of the inhabitants of the study area and the revenue of the Nigerian government. The major hotspots for oil spills in the Niger Delta region are Bayelsa, Rivers and Delta states.

Remediation of weathered diesel-oil contaminated soils using biopile systems: An amendment selection and pilot-scale study

Weathered diesel oil (WDO) has less biodegradable and volatile characteristics, and its bioremediation could be a challenge. In this study, the effectiveness of enhanced bioremediation via biopile processes for the cleanup of WDO-contaminated soils was evaluated. Six biopiles were constructed and operated with the following six different amendments addition: red bran (12 kg), water-soluble fertilizer (20 L/week), highly oxygenated water (20 L/d, dissolved oxygen = 25 mg/L), petroleum hydrocarbon-degrading bacterial culture (20 L/week), mixture of the above amendments, and natural attenuation (no amendment). Each biopile contained 5 m3 [2.5 m (L) × 2 m (W) × 1 m (H)] of WDO-contaminated soils [initial total petroleum hydrocarbon (TPH) concentrations = 3015 to 3785 mg/kg]. Soils were mixed with amendments and tilled for air supplement twice a week with soil moisture around 25%. Metagenomics analyses were applied to determine the microbial biodiversity and strains responsible for hydrocarbon biodegradation. Results show that the biopile system with mixed supplements (mixture group) had the highest TPH removal efficiency (79% of TPH removal) followed by red bran addition group with a removal efficiency of approximately 73% during the 42-day operation. The first-order TPH decay rates in mixture and red bran biopiles were around 3.2 × 10−2 1/d, which was 4.8 times higher than that obtained from natural attenuation biopile. Biopiles with red bran and mixture supplements contained carbon substrates and nutrients, which could effectively activate microbial activities and accelerate the TPH biodegradation. High carbon number compounds (C > 20) in WDO could be biodegraded within 24 days in the biopile with mixed amendments. Results from metagenomics study indicate that Sphingomonas and Pseudomonas might cause removal of heavy components (C24–30) and light components of petroleum hydrocarbons (C10–16), respectively.

Research on the effects of soil petroleum pollution concentration on the diversity of natural plant communities along the coastline of Jiaozhou bay

This study examines the 4 typical natural plant communities at the coastal waterfront of Jiaozhou Bay. Based on field survey and sampling, laboratory analysis, application of classical statistical methods and the requirements for urban ecological preservation and data restoration in IoT engineering technology, this study investigates the diversity pattern of the 4 natural plant communities, i.e. Phragmitesaustralis, Suaeda salsa, Setariaviridis and Conyzacanadensis, analyzes the characteristics of the petroleum pollution suffered by these 4 natural plant communities and the soil at the coastal waterfront of Jiaozhou Bay. By investigating the impact on the natural regulation ability of the natural ecosystem, species and habitat, this study provides the basis for protection of the natural plant communities in the petroleum polluted area and for the design of plants arrangement in ecological restoration in the site and provides the support for application of IoT technology in urban ecosystem establishment and urban ecological restoration. Findings: (1) During investigation of 30 quadrats of the plant communities in the petroleum polluted area at coastal waterfront of Qingdao, 74 plant species have been discovered.They belong to 12 families, where Chenopodiaceae, Poaceae and Compositae are dominant families and account for 9.09%, 20.45% and 38.63% respectively; Phragmitesaustralis, Suaeda salsa, Conyza canadensis and Setariaviridis communities are all herbosa, their species composition is quite simplex and most of them are in monodominant community patch; (2) The Conyzacanadensis community has the largest Shannon-Wiener diversity index, Patrick richness index and Simpson dominance index, which are 2.115, 1.930 and 1.228 respectively; in terms Pielou evenness index, the rank is Phragmitesaustralis > Conyzacanadensis > Setariaviridis > Suaeda salsa, which are 1.056, 0.907, 0.877 and 0.661; (3) According to the result of data analysis, the petroleum polluted area at coastal waterfront of Jiaozhou Bay has average total salt content 0.626%, average PH 8.067 and average petroleum hydrocarbons content 69.306 mg/kg.According to the result of difference examination of different plant communities, the total salt, PH and petroleum hydrocarbons content in the soil at the coastal waterfront Jiaozhou Bay are the main factors that affect the distribution of plant communities in that area (P < 0.05), and the petroleum hydrocarbons content in the soil has significant impact on the distribution of the communities (P < 0.01).(4) In this study, the petroleum hydrocarbon tolerance degrees of the 4 typical tolerant plant communities are ranked as Conyzacanadensis > Suaeda salsa > Setariaviridis > Phragmitesaustralis.In the soil environment with light (Level Ⅰ) and severe (Level Ⅳ) petroleum hydrocarbon pollution, the indexes of Suaeda salsa and Conyzacanadensis are optimal among the communities; the indexes of Phragmitesaustralis and Setariaviridis are optimal in the soil environment with Level Ⅱ and Level Ⅲ petroleum hydrocarbon pollution and can grow better in that environment.

Temporal (Monthly) Distribution and Variation of Total Petroleum Hydrocarbons Content in the Water and Sediments from Orashi River, Engenni, Rivers State, Nigeria

The total petroleum hydrocarbons content of the surface water and the sediments from the Orashi River were investigated between December 2019 and June 2020 at two months intervals to find out the level of contamination of the river. The total petroleum hydrocarbons were determined by GC-FID using Agilent 5890N, after following due laboratory procedures of sample pretreatment and clean-up. The results recorded from the surface water were December, 5.844±1.231 mg/L; February, 8.767±2.501 mg/L, April, 16.886±3.157 mg/L and June, 7.271±1.110 mg/L. Variation in concentration showed that April &gt; February &gt; June &gt; December. Results recorded in the sediments were December, 39.8427±13.5 mg/Kg; February, 29.5322±5.301 mg/Kg; April, 50.5040±16.813 mg/Kg and June; 16.6545±3.35 mg/Kg. The variation in concentration showed that April &gt; December &gt; February &gt; June. The variations observed in of total petroleum hydrocarbons content in the river indicated that the contamination source was primarily anthropogenic. It is therefore recommended that effective measures and adequate steps be taken by the government to mitigate the effect that may result from the accumulation of the total petroleum hydrocarbons in the river and on the aquatic inhabitants and man who depends on the river for daily living.

Pyrolysis of heavy hydrocarbons in weathered petroleum-contaminated soil enhanced with inexpensive additives at low temperatures

Pyrolysis is a promising technology for the remediation of soil contaminated with petroleum hydrocarbons. However, for weathered petroleum-contaminated soil (WPCS) with massive recalcitrant heavy hydrocarbons, pyrolysis still has the drawback of high energy consumption. To reduce energy consumption, commonly used inexpensive additives, including Fe2O3, Al2O3, K2CO3, CaO, HZSM-5, and red mud, were selected to strengthen the pyrolysis of heavy hydrocarbons in WPCS. The removal of the total petroleum hydrocarbon (TPH) content from WPCS increased as the dosage of additives increased from 1% to 5% at 400 °C for 30 min, and increased slightly or even decreased when the additive dosage was further increased to 10%. The reduction rates of the TPH content in soil treated with 5% additives of K2CO3, CaO, Fe2O3, red mud, HZSM-5, and Al2O3 increased by 26.16%, 25.65%, 25.53%, 23.93%, 23.15%, and 20.75%, respectively. Among these additives, CaO exhibited the best performance for the removal of aromatics (73.00%) and asphaltenes (72.44%), while Fe2O3 exhibited the best performance for the removal of resins (52.25%). The removal mechanisms of heavy hydrocarbons using additives during WPCS pyrolysis were proposed based on a combination of thermogravimetric analysis and the iso-conversional Flynn–Wall–Ozawa method. The reduction in the activation energy when additives were included during WPCS pyrolysis was closely related to whether the additives participated in the reaction and to the type of pyrolysis product. The soil characterization results demonstrated that the investigated additives would not severely impact further soil cultivation. The additive-assisted pyrolysis of WPCS is expected to reduce the required energy input by 34.71% compared to the traditional pyrolysis method, thus providing an energy-efficient and cost-effective method for treating petroleum-contaminated soil in future engineering applications.

Bioremediation Of Soil Of The Kola Peninsula (Murmansk Region) Contaminated With Diesel Fuel

This work focuses on the creation and use of associations of hydrocarbon-oxidizing microorganisms. Bioremediation of soils with the help of mixed cultural and associations of microorganisms provides wider adaptive possibilities than individual species. This is especially important in conditions of short northern summer. The results of field experiments showed that microbial associations based on indigenous microorganisms (bacteria Pseudomonas fluorescens, P. putida, P. baetica, Microbacterium paraoxydans and fungi Penicillium commune, P. canescens st. 1, P. simplicissimum st. 1) with mineral fertilizers reduced the content of total petroleum hydrocarbons in the Hortic Arthrosol soil of the Kola Peninsula by 82% over 120 days. Also, the microbial associations with mineral fertilizers had a positive effect on the physical properties of the soil, increasing its humidity. The bacterial-fungi associations changed the number, abundance and structure of the indigenous community of microorganisms. Penicillium canescens, which was included in the composition of fungi association, became dominant. During the rapid decomposition of hydrocarbons are released to the soil toxic intermediates or metabolites of the microbial oxidation of hydrocarbons. Hydrocarbon oxidizing microfungi suppressed the germination of test plant seeds to one degree or another. Penicillium commune fungal metabolites inhibited seed germination only by 29% for Lepidium sativum L. and 24% for Triticum aestivum L. This species can be used for bioremediation of petroleum contaminated soils.

Effectiveness of a bio-catalytic agent used in the bioremediation of crude oil-polluted seawater

Oil spillage contamination has been one of the most common and challenging problems in marine ecosystems over the years due to frequent petroleum exploitation, washing, and transportation activities. The use of nature-derived surfactants has become an attractive approach to restore the sites affected by oil spillage. Several studies have demonstrated that nutrient addition is an efficient strategy to enhance oil biodegradation since microorganisms can use petroleum hydrocarbons as their carbon and energy source, thus favoring and increasing the hydrocarbons degradation rate. This study aimed to assess the effectiveness of a commercial bio-catalytic agent used in the biological remediation of crude oil-contaminated sites through the qualitative analysis of its properties. The tests applied to this bio-catalyst showed excellent results. For instance, the emulsification (E24) and critical micellar concentration (CMC) assays displayed average values of 74.47% and 40 mg L−1, respectively. A significant reduction of Chemical Oxygen Demand (COD), turbidity, and Total Petroleum Hydrocarbon Content (TPHC) were observed in all the samples with bio-catalytic agent solution and aeration system. The best water quality was achieved by the sample with the highest concentration (10000 ppm) of bio-catalytic agent solution. It displayed a Total Petroleum Hydrocarbon removal efficiency (RTPH) of 81.537% after 30 days of the remediation time.

FITOREMEDIASI TANAH TERKONTAMINASI MINYAK BUMI DENGAN MENGGUNAKAN TANAMAN RUMPUT BAHIA (Paspalum notatum)

The increasing need for fuel derived from petroleum is also in line with the increased exploration and production activities of petroleum. Besides producing crude oil products, this activity also produces petroleum waste. This waste will pollute the soil which will have an impact on environmental damage, disruption of human health and other living things. Therefore according to Veegha (2008), an efficient and environmentally friendly method for treating petroleum waste is needed. One of the waste treatment methods is using phytoremediation method. Phytoremediation is defined as a technology for cleaning, removing or reducing harmful pollutants, such as heavy metals, pesticides, and toxic organic compounds in soil or water using the help of plants. This research was conducted for three months from September to November 2019 at the open nursery of PT. CPI with paranet shade 60%. This study aims to determine the effectiveness of bahia grass (P. notatum) in degrading Total Petroleum Hydrocarbon (TPH) in petroleum-contaminated soils in the Rokan Block PT. Chevron Pacific Indonesia and analyze the socio-economic impact of phytoremediation on local communities. The results showed that the effectiveness of Bahia (P. notatum) grass proved effective in reducing the concentration of Total Petroleum Hydrocarbon (TPH) in petroleum-contaminated soils in the Rokan Block operating area of PT. Chevron Pacific Indonesia. The percentage of effectiveness shows a decrease in value of up to 58.38%. The socio-economic impact of phytoremediation on local communities has a positive impact with the planned phytoremediation activities using bahia grass with the community as work agents for planting the grass.

A method for determining the content of petroleum hydrocarbons in soil

In this paper, ultrasonic - centrifugal extraction - infrared oil meter is used to determine petroleum hydrocarbons in soil.The optimal conditions of ultrasonic centrifugal extraction of petroleum hydrocarbons from soil were investigated by using simulated soil from the extraction agent, ultrasonic temperature, ultrasonic time, ultrasonic power, centrifugal speed, centrifugal time and other factors.The results showed that using tetrachloroethylene as extraction agent, the extraction efficiency of three times reached 88.34% with ultrasonic temperature of 30℃, ultrasonic time of 10min, ultrasonic power of 180W, centrifugal speed of 4000rpm and centrifugation time of 20min in 1% oil-contaminated soil.Under these conditions, the recoveries were 78.97%~96.58% and the relative standard deviations (n=5) of the measured values were 3.82%~12.53%.

Study of the oil geopermeation patterns: A case study of ANSYS CFX software application for computer modeling

Mathematical simulation of oil permeation through the porous media is the crucial topical problem in the framework of localization and liquidation of emergency oil spills. The main objective of this study was to establish the oil contamination level and oil contamination depth for different soil types which is of particular relevance from the standpoint of environmental safety. Four types of soils were taken for investigation as follows Cambisol with sand texture (No. 1), Luvisol (gray forest), with loamy sand texture (No. 2), Black Typical Chernozem with sandy loam texture (No. 3), Kastanozem (pine forest terrace under the pines) with sand texture (No. 4). The task of predicting the temporal-spatial indicators of oil permeation in the soil during accidental spills was solved using ANSYS CFX software allowing to simulate the absorption amount of oil into the ground. Visualization of oil concentration and velocity for studied soil samples was carried out. Determination of petroleum hydrocarbons concentration by the gravimetric method indicated a direct correlation between oil content in the soil and the porosity of the investigated soil samples. In order to determine the rate of hydrocarbon permeation through the dry and wet soil layer comparative experiments were carried out for the following systems: oil – dry soil and oil – wet soil. Permeation coefficients for dry samples from No. 1 to No. 4 were set at the rate 0.0073 m ∙ day−1, 0.0077 m ∙ day−1, 0.0083 m ∙ day−1, 0.0067 m ∙ day−1 respectively, and for wet soils 0.0083 m ∙ day−1, 0.0093 m ∙ day−1, 0.0093 m ∙ day−1, 0.0083 m ∙ day−1 consequently. The obtained hydrocarbon permeation coefficients for different systems allow calculating the depth of oil penetration for a given time after the spill, taking into account soil moisture. The dependence of oil concentration and permeation rate distribution through the soil fully reflects reliability of the experimental data, thereby confirming the verification of the adequacy of the computer model based on the ANSYS CFX software.

Isolation and Identification of Hydrocarbons- Degrading Bacteria from Panteka Stream, Kaduna, Nigeria, and Assessment of their Potential for Bioremediation

Water bodies become hydrocarbon-polluted when petroleum and other toxic organic matters are discharged into them. Panteka, located in northern Kaduna, Nigeria, is home to Panteka market, which is an industrial hub where different kinds of automobile spare parts are sold and mechanic workshops are situated. The Panteka stream flows through an entry point at Rafin guza, through Panteka market and towards the National Eye Centre. The indiscriminate disposal of spent engine oils and the discharge of other untreated effluents from car servicing workshops into the Panteka stream can lead to hydrocarbon contamination. Consequently, there is a need to identify these hydrocarbons and determine the capability of bacteria isolated from the stream to degrade the hydrocarbon pollutants. Using the pour plate method, and Bushnell Haas agar supplemented with 1% used engine oil, five bacterial isolates with the potential to degrade hydrocarbons were identified as Streptococcus pnuemoniae, Klebsiella pneumoniae, Shigella dysenteriae, Streptococcus pyogenes and Salmonella enterica. Salmonella enterica was confirmed by 16S rRNA gene sequencing and Basic Local Alignment search tool (BLAST) with a similarity index of 99%. The ability of the bacterial isolates to tolerate the spent engine oil was determined by turbidi metry. The results show that all the five bacterial isolates were able to tolerate the 1% (v/v) concentration of the spent engine oil. The highest growth rates (O.D 0.565 and O.D 0.695) were obtained from the pure cultures of Streptococcus pyogenes and the mixed bacterial consortium, respectively. The potentials of the bacteria to degrade hydrocarbons in the stream was analysed using Gas Chromatography Flame Ionization Detector (GC-FID), and the results showed reduction of the Total Petroleum Hydrocarbon (TPH) content from 6,056 mg/ml to 100.17 mg/ml (98.3% degradation) after 28 days of treatment with the mixed bacterial culture. The hydrocarbon fractions degraded were n-Nonane, n-Decane, n-Undecane, n- Dodecane, n-Tridecane, n-Tetradecane, n-Heptadecane, Pristane, n-octadecane, Phytane, n-Eicosane, n-Tricosane, n-Tetracosane, n-Octacosane, n-Triacontane, n-Dotriacontane, n-Tritriacontane, n-Heptriacontane; while n-Pentadecane, n-Hexadecane, n-Nonadecane, n-Heneicosane, n-Docosane, n-Pentacosane, n-Hexacosane, n-Heptacosane, n-Nonacosane, n-Hentriacontane, n-Tetratriacontane, n-Pentatriacontane, and n-Hexatriacontane were not degraded. This study shows that these bacterial strains isolated from the Panteka stream have great potential for bioremediation of the hydrocarbons found in the stream.&#x0D; Keywords: Bioremediation, Panteka stream, Automobile workshop, Hydrocarbon pollution, Bacteria isolates

CHEMICAL AND BIOLOGICAL INDICATORS FOR EVALUATION OF ARCTIC SOIL DEGRADATION AND ITS POTENTIAL TO REMEDIATION

In recent years, significant efforts have been made to accelerate the economic development of the Arctic zone, leading to intense environmental pollution of this region, accompanied by the significant impact of accumulated environmental damage in the region. The solution to these problems is difficult due to the remoteness of these areas and severe climatic conditions. Therefore, it is important to evaluate the potential for restoration of arctic soils. For this purpose, various indicators are used, including biological ones. In the analyzed arctic soil samples, high concentrations of petroleum hydrocarbons (up to 47,000 mg/kg) and chloride-ions (0.10–0.14 wt %) were established. Microbioassay demonstrated a presence of hydrocarbon-oxidizing microorganisms: Penicillium, Azotobacter chroococcum, Bacillus subtilis, Pseudomonas oleovorans. A low enzymatic activity and specific Arctic climate point out a low self-restoration ability of the soil, demonstrated the need for its remediation. The microbioassay with microbial strains identification and soil remediation methods suitable for the Arctic zone were recommended.

A Combinational Strategy Mitigated Old-Aged Petroleum Contaminants: Ineffectiveness of Biostimulation as a Bioremediation Technique.

Hydrocarbon contamination emerging from the crude oil industrial-related activities has led to severe environmental issues. Prolonged contamination with the constant infiltration of crude oil into the soil is a severe problem in remediating contaminated soils. Hence, the current study focuses on comparing various bioremediation strategies, thereby isolating native bacteria competent to reduce TPH in both liquid and microcosm environments in an old-aged petroleum hydrocarbon contaminated soil. Assays in the modified 6SW-Vit medium after 7 days of incubation revealed that Bacillus altitudinis strain HRG-1 was highly hydrophobic and had a suitable ability to decrease surface tension (40.98%) and TPH (73.3%). The results of biodegradation in the microcosm proved that among the designated treatments, including bio-stimulated microcosm (SM), bacterialized microcosm (BM), a combined bio-stimulated microcosm and bacterialized microcosm (SB), and natural attenuation (NA), the SB treatment was the most effective in mitigating TPH (38.2%). However, the SM treatment indicated the lowest TPH biodegradation (18%). Pearson correlation coefficient among microcosm biological indicators under investigation revealed that soil basal respiration had the highest correlation with the amount of residual TPH (r = −0.73915, P < 0.0001), followed by the microbial population (r = −0.65218, P < 0.0001), catalase activity (r = 0.48323, P = 0.0028), polyphenol oxidase activity (r = −0.43842, P = 0.0075), and dehydrogenase activity (r = −0.34990, P = 0.0364), respectively. Nevertheless, considering the capability of strain HRG-1 and the higher efficiency of the combined technique, their use is recommended to diminish the concentration of petroleum hydrocarbons in hot and dry contaminated areas.

Detailed chemical characterization of the composition and variability of soil gas at remediated residential heating oil discharges

Underground storage tanks containing petroleum or other hazardous substances are used widely for residential storage of home heating oil. Spills and leaks of fuel from these tanks are common, and resulting subsurface petroleum vapors may pose health risks. However, understanding of this risk is limited by a lack of observational data on the chemical composition of vapors from discharged fuel. We present here the composition of soil gas sampled at 66 remediated residential sites of underground heating oil discharges throughout Virginia using a newly developed data analysis technique that allows characterization of hydrocarbons by carbon number and degree of unsaturation. Measured concentrations of total petroleum hydrocarbons exceeded 100,000 μg/m3 at 12 sites, but its composition varied widely between sites. Concentrations of hydrocarbons from chemical classes differing by more than a few carbon numbers or degrees of unsaturation are found to be poorly correlated. Furthermore, differences in composition are poorly described by metrics expected to indicate subsurface weathering (e.g., discharge year, or ratio of n-heptadecane to pristane). These results suggest that the composition and magnitude of residual contamination at remediated subsurface discharges is driven by rarely documented spill characteristics (e.g., age and composition of source material, discharge rate, etc.).