Petroleum-polluted Soil Research Articles

Low dose phosphorus supplementation is conducive to remediation of heavily petroleum-contaminated soil—From the perspective of hydrocarbon removal and ecotoxicity risk control

Biostimulation by supplementing of nitrogen and phosphorus nutrients is a common strategy for remediation of petroleum-polluted soils. However, the dosage influence of exogenous nitrogen or phosphorus on petroleum hydrocarbon removal and soil ecotoxicity and microbial function remain unclear. In this study, we compared the efficiencies of hydrocarbon degradation and ecotoxicity control by experiment conducted over addition of inorganic nitrogen or phosphorus at C/N ratio of 100/10, C/N/P ratio of 100/10/1, and C/P ratio of 100/1 in a heavily petroleum-contaminated loessal soil with 12,320 mg/kg of total petroleum hydrocarbon (TPH) content. A 90-day incubation study revealed that low-dose of phosphorus addition with the C/P ratio of 100/1 promoted hydrocarbon degradation and reduced soil ecotoxicity. Microbial community composition analysis suggested that phosphorus addition enriched hydrocarbon degrader Gordonia and Mycolicibacterium genus. The key enzymes EC 5.3.3.8, EC 6.2.1.20 and EC 6.4.1.1 which referred to degradation of long-chain hydrocarbons, unsaturated fatty acids and pyruvate metabolism were abundance by phosphorus supplementation. While nitrogen addition at C/N ratio of 100/10 or C/N/P ratio of 100/10/1 inhibited hydrocarbon degradation and exacerbated soil ecotoxicity due to promoting denitrification and coupling reactions with hydrocarbons. Our results suggested that low-dose phosphorus addition served as a favorable strategy to promote crude oil remediation and ecotoxicity risk control in heavily petroleum-contaminated soil. Hence, the application of suitable doses of exogenous biostimulants is an efficient approach to restore the ecological functions of organically contaminated soils.

Contaminant Removal in Soil and Wash Water Residue from Ex-Mining Area in Jambi using Soil Washing Remediation

Soil washing is one of the effective methods to remove contaminants in polluted soil by moving them from the solid phase (soil) to the liquid phase (water). This study examines the effect of soil washing on the concentration of Total Petroleum Hydrocarbon (TPH) in petroleum-polluted soil at the Ex-Mining Area in Jambi and the removal of oil and grease in soil washing residue using a fixed bed column. The soil washing method uses a leaching column with various concentrations of Tween 80 surfactant solution of 0.5% (v/v) and 1% (v/v). In addition, leaching was repeated 0, 1, and 2 times. Coffee husk biochar was used as a medium in a fixed bed column to remove oil and grease from soil-washing residue with thickness variations of 10 cm, 20 cm, and 30 cm. The results showed that the soil was loamy sand with an initial TPH content of 3092.75 mg/kg. The soil-washing process reduced the TPH concentration with a removal efficiency of 72.45-90.40%. The highest TPH removal occurred in one leaching repetition at a 0.5% surfactant concentration. The optimum oil and fat removal from the use of a fixed bed column is at 30 cm thickness which is 94.35%.

Sulfur-containing iron carbon nanocomposites activate persulfate for combined chemical oxidation and microbial remediation of petroleum-polluted soil

In this study, sulfur-containing iron carbon nanocomposites (S@Fe-CN) were synthesized by calcining iron-loaded biomass and utilized to activate persulfate (PS) for the combined chemical oxidation and microbial remediation of petroleum-polluted soil. The highest removal efficiency of total petroleum hydrocarbons (TPHs) was achieved at 0.2% of activator, 1% of PS and 1:1 soil-water ratio. The EPR and quenching experiments demonstrated that the degradation of TPHs was caused by the combination of 1O2,·OH, SO4·-, and O2·-. In the S@Fe-CN activated PS (S@Fe-CN/PS) system, the degradation of TPHs underwent two phases: chemical oxidation (days 0 to 3) and microbial degradation (days 3 to 28), with kinetic constants consistent with the pseudo-first-order kinetics of chemical and microbial remediation, respectively. In the S@Fe-CN/PS system, soil enzyme activities decreased and then increased, indicating that microbial activities were restored after chemical oxidation under the protection of the activators. The microbial community analysis showed that the S@Fe-CN/PS group affected the abundance and structure of microorganisms, with the relative abundance of TPH-degrading bacteria increased after 28 days. Moreover, S@Fe-CN/PS enhanced the microbial interactions and mitigated microbial competition, thereby improving the ability of indigenous microorganisms to degrade TPHs.

The discrepant metabolic pathways of PAHs by facultative anaerobic bacteria under aerobic and nitrate-reducing conditions

Studies regarding the facultative anaerobic biodegradation of polycyclic aromatic hydrocarbons (PAHs) were still in the initial stage. In this study, a facultative anaerobe which was identified as Bacillus Firmus and named as PheN7 was firstly isolated from the mixed petroleum-polluted soil samples using phenanthrene and nitrate as the solo carbon resource and electron acceptor under anaerobic condition. The degradation rates of PheN7 towards phenanthrene were detected as 33.17 μM/d, 13.81 μM/d and 7.11 μM/d at the initial phenanthrene concentration of 250.17 μM with oxygen, nitrate and sulfate as the electron acceptor, respectively. The metabolic pathways toward phenanthrene by PheN7 were deduced combining the metagenome analysis of PheN7 and intermediate metabolites of phenanthrene under aerobic and nitrate-reducing conditions. Dioxygenation and carboxylation were inferred as the initial activation reactions of phenanthrene degradation in these two pathways. This study highlighted the significance of facultative anaerobic bacteria in natural PAHs biodegradation, revealing the discrepant metabolic fates of PAHs by one solo bacteria under aerobic and anaerobic environments.

Microbial functional heterogeneity induced in a petroleum-polluted soil profile

Microbial taxonomic diversity declines with increasing stress caused by petroleum pollution. However, few studies have tested whether functional diversities vary similarly to taxonomic diversity along the stress gradient. Here, we investigated soil microbial communities in a petrochemically polluted site in China. Total petroleum hydrocarbon (TPH) concentrations were higher in the middle (2–3 m) and deep soil layer (3–5 m) than in the surface soil layer (0–2 m). Accordingly, microbial taxonomic α-diversity was decreased by 44% (p < 0.001) in the middle and deep soil layers, compared to the surface soil layer. In contrast, functional α-diversity decreased by 3% (p < 0.001), showing a much better buffering capacity to environmental stress. Differences in microbial taxonomic and functional β-diversities were enlarged in the middle and deep soil layers, extending the Anna Karenina Principle (AKP) that a community adapts to stressful environments in its own way. Consistent with the stress gradient hypothesis, we revealed a higher degree of network connectivity among microbial species and genes in the middle and deep soil layers compared to the surface soil layer. Together, we demonstrate that microbial functionality is more tolerant to stress than taxonomy, both of which were amenable to AKP and the stress gradient hypothesis.

Simultaneous remediation of diesel-polluted soil and promoted ryegrass growth by non-thermal plasma pretreatment

The remediation of petroleum-polluted soil has garnered significant global attention. In this study, a pot-culture experiment was conducted to assess the feasibility of using non-thermal plasma (NTP) as an efficient and economic-friendly pretreatment method in the phytoremediation of diesel-polluted soil. The remediation effectiveness was evaluated via both the removal of diesel and the ryegrass growth. Specifically, at the 50th d of ryegrass growth, the increase of diesel removal efficiency with NTP pretreatment ranged from 16 % to 30 %. Moreover, both clean and diesel-polluted soils pretreated by NTP promoted the growth of ryegrass in shoot lengths and biomass especially after the 35th d. It was found that nitrate nitrogen fixed by NTP not only stimulated the nitrate reductase activities in leaves and promoted plant growth, but also was transformed to more ammonia nitrogen for organism life activity. Subsequent investigation proved that the related nitrogen-metabolism activities of microbes were enriched in rhizosphere soils with NTP pretreatment. Furthermore, NTP treatment increased the abundance of beneficial microbial communities in diesel soil rhizosphere on the 42nd d of growth period. In addition, changes in the proportions of soil dissolved organic matter indicated enhanced nutrient cycling in soils with NTP pretreatment. These promotional effects underscored the contribution of NTP pretreatment in rapidly detoxifying diesel-contaminated soil within 10 min and accelerated the establishment of ryegrass ecosystem. This study provides valuable insights into the role of nitrogen fixation and offers an efficient and promising advanced approach for the phytoremediation of diesel-polluted soil with NTP pretreatment.

Remediation Approaches to Reduce Hydrocarbon Contamination in Petroleum-Polluted Soil.

Heavy metals pollution associated with oil spills has become a major concern worldwide. It is essential to break down these contaminants in the environment. In the environment, microbes have been used to detoxify and transform hazardous components. The process can function naturally or can be enhanced by adding nutrients, electron acceptors, or other factors. This study investigates some factors affecting hydrocarbon remediation technologies/approaches. Combinations of biological, chemical, and eco-toxicological techniques are used for this process while monitoring the efficacy of bacterial products and nutrient amendments to stimulate the biotransformation of contaminated soil. Different hydrocarbon removal levels were observed with bacterial augmentation (Beta proteobacterium and Rhodococcus ruber), exhibiting a total petroleum hydrocarbon (TPH) reduction of 61%, which was further improved to a 73% reduction using bacterial augmentation combined with nutrient amendment (nitrogen, potassium, and phosphorus). A heavy metal analysis of the polluted soils showed that the combination of nutrient and bacterial augmentation resulted in a significant reduction (p-value < 0.05) in lead, zinc, and barium. Toxicity testing also showed that a reduction of up to 50% was achieved using these remediation approaches.

Biochar-mediated remediation impacts on nitrogen cycling bacteria and ammonia monooxygenase activity in crude oil polluted soil

This study adopted an ecosystem services approach to pollution management by investigating the impact of biochar-mediated remediation on soil nitrogen, abundance of nitrogen cycling bacteria and the activity of ammonia monooxygenase (AMO) enzyme in petroleum-polluted soil using two biochar types applied at two treatment levels with monitoring over 15 weeks. The corn cob-derived biochar (CDB), generally, had a stronger restorative effect on soil ammonium nitrogen, nitrate and total organic nitrogen concentrations than the bone-derived biochar (BDB). Both biochar types had a more robust impact on restoration of Nitrosomonas, Nitrobacter and Azotobacter abundance (with the re-establishment of pre-pollution levels) than on Rhizobium and Pseudomonas aeruginosa. Biochar amendment restored the activity of AMO enzyme in the soil by week 15. The CDB (72.4% – 73.7%) showed more effective total petroleum hydrocarbon (TPH) elimination capacity than the BDB (51.1% – 57.7%). Biochar amendments exhibited great potential for restoration of nitrogen cycling while facilitating remediation of petroleum-polluted soils.

Petroleum-Degrading Fungal Isolates for the Treatment of Soil Microcosms.

The main purpose of this study was to degrade total petroleum hydrocarbons (TPHs) from contaminated soil in batch microcosm reactors. Native soil fungi isolated from the same petroleum-polluted soil and ligninolytic fungal strains were screened and applied in the treatment of soil-contaminated microcosms in aerobic conditions. The bioaugmentation processes were carried out using selected hydrocarbonoclastic fungal strains in mono or co-cultures. Results demonstrated the petroleum-degrading potential of six fungal isolates, namely KBR1 and KBR8 (indigenous) and KBR1-1, KB4, KB2 and LB3 (exogenous). Based on the molecular and phylogenetic analysis, KBR1 and KB8 were identified as Aspergillus niger [MW699896] and tubingensis [MW699895], while KBR1-1, KB4, KB2 and LB3 were affiliated with the genera Syncephalastrum sp. [MZ817958], Paecilomyces formosus [MW699897], Fusarium chlamydosporum [MZ817957] and Coniochaeta sp. [MW699893], respectively. The highest rate of TPH degradation was recorded in soil microcosm treatments (SMT) after 60 days by inoculation with Paecilomyces formosus 97 ± 2.54%, followed by bioaugmentation with the native strain Aspergillus niger (92 ± 1.83%) and then by the fungal consortium (84 ± 2.21%). The statistical analysis of the results showed significant differences.

Metagenomic analysis of the microbial community at the Riutort oil shale mine (NE Spain): Potential applications in bioremediation and enhanced oil recovery

Preservation of the environment of the Riutort oil shale mine for more than a century has favored the presence of a paradigmatic ecosystem of oil-degrading microorganisms. After extensive sampling and analysis by 16S rRNA sequencing, a marked prokaryotic community comprising diverse groups of bacteria (genus such as Methylobacter, Thiothrix, and Desulfobacca) and archaea (e.g., Methanobrevibacter genus) with hydrocarbon-degrading activity was found. Aerobic microorganisms were predominant in several samples but facultative microorganisms were also present, and there was an interesting transition to strict anaerobic conditions in some areas. One of the samples contained oil degrading aerobic bacteria such as Pseudomonas spp. and Brevundimonas spp. Of the microbes studied, we conducted a laboratory assessment of the capacity of this specific consortium for bioremediation of petroleum-polluted soil and microbial enhanced oil recovery processes. To this end, we used oily sludge-contaminated soil from La Libertad Refinery and cores from the Ancón Field, respectively, both sites in southwestern Ecuador. The Riutort consortium degraded 50.8% of total petroleum hydrocarbons, 64.2% of saturates, 41.3% of aromatics, and 37.4% of polar compounds after a 60-day incubation using oily sludge as the sole source of carbon. The performance of this consortium reflects its notable potential for bioremediation purposes. In turn, flooding with the natural Riutort consortium and its metabolites achieved a 7.2% (v/v) incremental recovery of crude oil through a sand-pack assay. These results are comparable to those reported using synthetic bacterial consortia, and thus reveal the great interest of the study seepages, not only for understanding microbial activities in oil degradation but also their use in biotechnological applications.

Bioavailability as a tool for planning bioremediation of petroleum-polluted soil

Soil pollution scenarios are every time more often and bioremediation is a well-known strategy to remove pollutants from soil. In theory, only the bioavailable fractions of a pollutant might be degraded using bioremediation. This hypothesis was tested via the estimation of bioavailable petroleum-hydrocarbons in polluted clay soil and measurements on the biodegradation of the hydrocarbons in bioremediation systems at both laboratory (ideal conditions) and field conditions (treatment units of 120 m3 on landfarming and windrow configurations). A non-exhaustive extraction technique with 50% 1-propanol was used to estimate bioavailability. Treatment efficiencies (based on the total concentration of the pollutant) were 47.27 and 45.83% at laboratory and field conditions, respectively. Bioremediation efficiencies (based on the bioavailable fraction of the pollutant) were 92.66 and 88.76% for laboratory and field conditions, respectively. These results suggest that bioavailability might be used as a tool to set up feasible biodegradation goals.

Utilization of Vermicompost and Earthworms (Lumbricus Rubellus) for Bioremediation of Petroleum Polluted Soils

As one of the petroleum-producing countries, Indonesia is vulnerable to pollution and environmental damage due to petroleum mining activities. Petroleum contains harmful hydrocarbon compounds and can harm the ecosystem of surrounding living things. The hydrocarbon compounds in petroleum are so numerous that to determine petroleum pollution in the soil, the Total Petroleum Hydrocarbon (TPH) parameter is used to represent these hydrocarbon compounds. One of the efforts to overcome the problem of soil pollution by petroleum can be done using biological methods known as bioremediation. Bioremediation is one of the essential alternative technologies because this effort is considered more economical and safe for the environment, although it takes longer. In this study, the technology applied was bioremediation using the vermicomposting technique. This study examined the bioremediation process using the vermicomposting technique by adding vermicompost and earthworms (Lumbricus rubellus) to overcome soil pollution due to petroleum waste. Based on the study's results, the composition of the mixture of oil-contaminated soil with vermicompost in a ratio of 1:2 (w/w) coupled with 25 worms can reduce the TPH level by 89.63%. The addition of vermicompost leads to an increase in soil porosity so that oxygen transfer for the survival of earthworms and the activity of degrading microbes during the bioremediation process is better than before.ABSTRAKIndonesia sebagai salah satu negara penghasil minyak bumi rentan terhadap risiko pencemaran dan kerusakan lingkungan akibat aktivitas pertambangan minyak bumi. Minyak bumi mengandung senyawa hidrokarbon berbahaya, serta dapat merugikan ekosistem makhluk hidup sekitarnya. Senyawa hidrokarbon dalam minyak bumi sangat banyak sehingga untuk menentukan pencemaran minyak bumi pada tanah digunakan parameter Total Petroleum Hydrocarbon (TPH) untuk mewakili senyawa-senyawa hidrokarbon tersebut. Salah satu upaya penanggulangan masalah pencemaran tanah oleh minyak bumi tersebut dapat dilakukan menggunakan cara biologi yang dikenal dengan isitilah bioremediasi. Bioremediasi merupakan salah satu teknologi alternatif penting karena upaya ini dianggap lebih ekonomis dan aman bagi lingkungan, walaupun membutuhkan waktu yang lebih lama. Dalam penelitian ini, teknologi yang diterapkan adalah bioremediasi menggunakan teknik vermicomposting. Penelitian ini dilakukan untuk mengkaji proses bioremediasi dengan menggunakan teknik vermicoposting dengan menambahkan vermikompos dan cacing tanah (Lumbricus rubellus) sebagai upaya penanggulangan pencemaran tanah akibat limbah minyak bumi. Berdasarkan hasil penelitian, komposisi campuran tanah terkontaminasi minyak dengan vermikompos dengan perbandingan 1:2 (b/b) yang ditambah dengan 25 ekor cacing bisa menurunkan kadar TPH sebesar 89.63%. Penambahan vermikompos menyebabkan peningkatan porositas tanah sehingga transfer oksigen untuk kelangsungan hidup cacing tanah dan aktivitas mikroba pendegradasi selama proses bioremediasi menjadi lebih baik

Heavy Metal Tolerance profile among Bacterial species Isolated from Hydrocarbon polluted sites and their mobile genetic elements

This present study evaluated the plasmid incidence in bacteria and their genetic elements in heavy metals tolerant-antibiotics resistant microbes isolated from petroleum hydrocarbon polluted sites. The plasmid isolation was carried out using the fermentas Genejet plasmid miniprep kit (Thermofisher Scientific Inc, USA). Screening for class 1, 2, and 3 integrons, incompatibility group P testing, plasmid replicon typing, plasmid restriction analysis, and other analysis was performed using standard laboratory procedures. Plasmid incidences were higher among multiple heavy metal-tolerant bacterial species from hydrocarbon-polluted sites than those from the pristine site. Further, Class 1 integron incidence was significantly higher among the integrons in heavy metal tolerant bacterial isolates isolated from the polluted ecosystems than those from pristine ecosystems. Plasmid replicon type of bacteria with multiple heavy metal tolerance and antibiotics resistance indexes revealed that IncN plasmid replicon type carrying class 1 integron. This encodes resistance to sulphamethazole/trimethoprim, ampicillin, and tolerance to Cd, Ni, and Cu in Klebsiella pneumoniae isolate from petroleum-polluted soil. This is the first report of IncN plasmid in environmental bacteria in Nigeria, particularly from petroleum polluted environment. The conjugation experiment confirmed the possible transferability of antibiotic resistance determinants among isolates in polluted ecosystems. From the results of this study, it can be concluded that petroleum hydrocarbon pollution vis-a-vis heavy metal selective pressure with the abundance of mobile genetic elements amongst isolates from polluted ecosystems could contribute to the dispersing of antibiotic resistance genes, thus posing a serious public health concern.

Identification of a strain of Auricularia and Taguchi optimization of petroleum-polluted soil mycoremediation

Petroleum contamination has become a serious global concern due to adverse effects on terrestrial ecosystems. Bioremediation has been known as one of the most effective and economical solutions to reduce and eliminate pollutions caused by petroleum compounds. In this study, mycoremediation of contaminated soil was evaluated using a strain of Auricularia to simultaneously produce high-value biomass. Pre-culture media was prepared by growing the fungus on different lignocellulosic materials derived from agricultural wastes. Sequence analysis of the Internal Transcribed Spacer (ITS) regions confirmed that the strain belonged to Auricularia auricularia-judae with high homology. A four-factor Taguchi design was then adopted to determine the optimal points of temperature (25 and 35 °C), type of media (mixtures of rice bran, tea waste, wheat straw, corn sticks, and sawdust), inoculum size (2 and 6 g), and nitrogen source (urea, ammonium nitrate, and nitrogen-free). The findings indicated that after 45 d, the mixture of rice bran, sawdust, and tea waste with 6 g inoculum in the absence of nitrogen at 35 °C ended up in striking efficiency of 71%. To the best of our knowledge, the study is a highly efficient bioremediation of petroleum-polluted soils using an edible strain of fungus. High degradation performance of Auricularia highlights the crucial role of lignocellulosic waste materials for biodegradation process.

Migration Behavior and Influencing Factors of Petroleum Hydrocarbon Phenanthrene in Soil around Typical Oilfields of China

Petroleum spills and land contamination are becoming increasingly common around the world. Polycyclic aromatic hydrocarbons (PAHs) and other pollutants found in petroleum are constantly migrating underground, making their migration in soil a hot research topic. Therefore, it is of great significance to evaluate the migratory process of petroleum hydrocarbons in petroleum-polluted soil to clarify its ecological and environmental risks. In this study, Phenanthrene (PHE) was used as a typical pollutant of PAHs. The soil was gathered from three typical oilfields in China, and a soil column apparatus was built to simulate the vertical migration of PHE in the soil. The migration law and penetration effect of PHE in various environmental conditions of soil were investigated by varying the ionic strength (IS), pH, particle size, and type of soil. According to the literature, pH has no discernible effect on the migration of PHE. The migration of PHE was adversely and positively linked with changes in IS and soil particle size, respectively. The influence of soil type was mainly manifested in the difference of organic matter and clay content. In the Yanchang Oilfield (YC) soil with the largest soil particle size and the least clay content, the mobility of PHE was the highest. This study may reveal the migration law of PAHs in soils around typical oilfields, establish a new foundation for PAH migration in the soil, and also provide new ideas for the management and control of petroleum pollution in the soil and groundwater.

Effect of remediation techniques on petroleum removal from and on biological activity of a drought-stressed Kastanozem soil.

Many petroleum extraction and refinement plants are located in arid climates. Therefore, the remediation of petroleum-polluted soils is complicated by the low moisture conditions. We ran a 70-day experiment to test the efficacy of various combining of remediation treatments with sorghum, yellow medick, and biochar to remove petroleum from and change the biological activity of Kastanozem, a soil typical of the dry steppes and semideserts of the temperate zone. At normal moisture, the maximum petroleum-degradation rate (40%) was obtained with sorghum-biochar. At low moisture, the petroleum-degradation rate was 22 and 30% with yellow medick alone and with yellow medick - sorghum, respectively. Biochar and the biochar-plant interaction had little effect on soil remediation. Both plants promoted the numbers of soil microbes in their rhizosphere: yellow medick promoted mostly hydrocarbon-oxidizing microorganisms, whereas sorghum promoted both hydrocarbon-oxidizing and total heterotrophic microorganisms. Low moisture did not limit microbial development. In the rhizosphere of sorghum, dehydrogenase and urease activities were maximal at normal moisture, whereas in the rhizosphere of yellow medick, they were maximal at low moisture. Peroxidase activity was promoted by the plants in unpolluted soil and was close to the control values in polluted soil. Biochar and the biochar-plant interaction did not noticeably affect the biological activity of the soil.

Bioremediation of Soil from Petroleum Contamination

Petroleum is the most common global fossil fuel. It is a complex multi-component system mainly composed of various hydrocarbons such as alkanes, cycloalkanes, mono-, bi- and polyaromatic compounds, resins and asphaltenes. In spite of humanity’s need for petroleum, it negatively affects the environment due to its toxicity. The ecological problem is especially serious at petroleum mining sites or during petroleum transportation. Since it is not possible to replace petroleum with less toxic fuel, ways to reduce the toxic impact of petroleum hydrocarbons on the environment need to be developed. This review addresses bioremediation, a biological approach to petroleum degradation, which is mainly performed by microbes. The pathways of degradation of alkanes, alkenes and aromatic hydrocarbons are presented in detail. The effects of temperature, aeration and the presence of biogenic elements on microbial degradation of petroleum are discussed. Plant–microbe interactions involved with the bioremediation of petroleum-polluted soils are specifically addressed. The data presented in this review point to the great potential of bioremediation practices for cleaning soils of petroleum.

Bioremediation of Petroleum-Polluted Soil Using Biosurfactant Producing Bacteria, Pseudomonas sp.

Bioremediation of Petroleum-Polluted Soil Using Biosurfactant Producing Bacteria, Pseudomonas sp.

Fast analysis of derivatives of polycyclic aromatic hydrocarbons in soil by ultra-high performance supercritical fluid chromatography after supercritical fluid extraction enrichment

An efficient and environment-friendly method for simultaneous determination of 13 typical derivatives of polycyclic aromatic hydrocarbon (PAH) in petroleum-polluted soil with nitro-, oxy- and alkyl-functional group was developed using supercritical fluid extraction (SFE) followed by ultra-high performance supercritical fluid chromatography (UHPSFC). Parameters of UHPSFC, including type of stationary phase and mobile phase modifiers, gradient elution process, backpressure, column temperature, and the flow rate of mobile phase, were systematically optimized, achieving a fast separation within 4.2 min. Limits of detection (LOD) were 0.005–0.1 μg mL−1 or 0.1–2.0 ng g−1, respectively, with a good repeatability (RSD<5.0%). Before UHPSFC-PDA analysis, the PAH-derivatives in soil samples were effectively enriched in 15.0 min using SFE with an online carbon nanotubes (CNTs) collection trap. The soil samples were analyzed by the proposed method and the results were verified by GC-MS. Thus, SFE equipped with an online CNTs trap followed by UHPSFC-PDA analysis, which only consumed about 2.0 mL organic solvent for a whole run, has been demonstrated to be an efficient way for screening and quantitative analysis of trace-level PAH-derivatives in soil samples.

Exploration of the biotransformation of phenanthrene degradation coupled with methanogensis by metabolites and enzyme analyses

The ubiquitous environmental contaminants, polycyclic aromatic hydrocarbons (PAHs), can be aerobically biodegraded. Strategies for biodegradation of PAHs are needed for the persisted character of it in anoxic environments. In current study, we obtained a highly enriched anaerobic, PAHs-degrading co-culture DYM1, from petroleum-polluted soil. DYM1 significantly degrades a range of PAHs in 4 days without supplementary terminal electron acceptors. Co-culture DYM1 is consists of two microorganisms (a degrading bacterium Paracoccus sp. strain PheM1 and an aceticlastic methanogen Methanosaeta concilii.) that utilize different carbon sources in a syntrophic metabolic process of phenanthrene. About 93% of phenanthrene (104.5 μM) has been removed under methanogenic conditions after incubation with co-culture DYM1 for 4 d, and produced 33.68 μmol CH4. Carboxylation, which is catalyzed by UbiD-like carboxylase, was proposed as the initial steps of methanogenic phenanthrene-degrading pathway based upon the detection of 2-phenanthroic acid and 4-phenanthrene acid. Reduction and hydration of the benzene rings were followed by the initial reaction. Hydrated phenanthroic acid metabolites were newly detected and characterized under anaerobic conditions. Anaerobic degradation of phenanthrene without terminal electron acceptor addition not only sheds light on a poorly understood and environmentally relevant biological process, but also supply a novel approach to recover the energy of toxic pollutant in forms of methane.