Search Results (319)

The topic of environmental pollution by petroleum products is highly relevant due to rapid urbanisation, including industrial development, road infrastructure and fuel distribution. Potential threat areas include refineries, fuel stations, pipelines, warehouses and transshipment bases, as well as sites affected by accidents or fuel spills. This study aimed to determine whether organic and mineral materials could mitigate the effects of diesel oil pollution on the soil’s trace element content. The used materials were compost, bentonite and calcium oxide. Diesel oil pollution had the most pronounced effect on the levels of Cd, Ni, Fe and Co. The levels of the first three elements increased, while the level of Co decreased by 53%. Lower doses of diesel oil (2.5 and 5 cm³ per kg of soil) induced an increase in the levels of the other trace elements, while higher doses caused a reduction, especially in Cr. All materials applied to the soil (compost, bentonite and calcium oxide) reduced the content of Ni, Cr and Fe. Compost and calcium oxide also increased Co accumulation in the soil. Bentonite had the strongest reducing effect on the Ni and Cr contents of the soil, reducing them by 42% and 53%, respectively. Meanwhile, calcium oxide had the strongest reducing effect on Fe and Co accumulation, reducing it by 12% and 31%, respectively. Inverse relationships were recorded for Cd (mainly bentonite), Pb (especially compost), Cu (mainly compost), Mn (mainly bentonite) and Zn (only compost) content in the soil. At the most contaminated site, the application of bentonite reduced the accumulation of Pb, Zn and Mn in the soil, while the application of compost reduced the accumulation of Cd. Applying various materials, particularly bentonite and compost, limits the content of certain trace elements in the soil. This has a positive impact on reducing the effect of minor diesel oil pollution on soil properties and can promote the proper growth of plant biomass. Full article

Petroleum-derived contaminants pose a significant threat to the soil microbiome. Therefore, it is essential to explore materials and techniques that can restore homeostasis in disturbed environments. The aim of the study was to assess the response of the soil microbiome to contamination with diesel oil (DO) and gasoline (G) and to determine the capacity of sorbents, vermiculite (V), dolomite (D), perlite (P) and agrobasalt (A), to enhance the activity of microorganisms under Zea mays cultivation conditions in pot experiments. The restoration and activity of the soil microbiome were evaluated based on the abundance and diversity of bacteria and fungi, using both classical microbiological methods and Next Generation Sequencing (NGS). Bioinformatic tools were employed to calculate the physicochemical properties of proteins. DO increased the abundance of cultured microorganisms, whereas G significantly reduced it. Both DO and G increased the number of ASVs of Proteobacteria and decreased the relative abundance of Gemmatimonadetes, Chloroflexi, Acidobacteria, Verrucomicrobia, Planctomycetes, and fungal OTUs. These contaminants stimulated the growth of bacteria from the genera Rhodanobacter, Sphingomonas, Burkholderia, Sphingobium, and Mycobacterium, as well as fungi belonging to the Penicillium genus. Conversely, they had a negative effect on Kaistobacter, Rhodoplanes, and Ralstonia, as well as the fungi Chaetomium, Pseudaleuria, and Mortierella. DO caused greater changes in microbial alpha diversity than G. The stability of microbial proteins was higher at 17 °C than at −1 °C. The most stable proteins were found in bacteria and fungi identified within the core soil microbiome. These organisms exhibited greater diversity and more compact RNA secondary structures. The application of sorbents to contaminated soil altered the composition of bacterial and fungal communities. All sorbents enhanced the growth of organotrophic bacteria (Org) and fungi (Fun) in DO-contaminated soils, and actinobacteria (Act) and fungi in G-contaminated soils. V and A had the most beneficial effects on cultured microorganisms. In DO-contaminated soils, all sorbents inhibited the growth of Rhodanobacter, Parvibaculum, Sphingomonas, and Burkholderia, while stimulating Salinibacterium and Penicillium. In G-contaminated but otherwise unamended soils, all sorbents negatively affected the growth of Burkholderia, Sphingomonas, Kaistobacter, Rhodoplanes, Pseudonocardia, and Ralstonia and increased the abundance of Gymnostellatospora. The results of this study provide a valuable foundation for developing effective strategies to remediate soils contaminated with petroleum-derived compounds. Full article

Heavy oil, due to its complex hydrocarbon structure and resistance to degradation, poses significant environmental challenges. There is a lack of knowledge about the biodegradability of heavy oil in the natural environment under aerobic and anaerobic conditions. In this study, we used microbial communities of water and soil samples to investigate the biodegradation of heavy oil. Gas chromatography (GC) analysis was used to measure residual oil. Under aerobic conditions, soil-derived microorganisms demonstrated significantly higher degradation efficiency—achieving up to 80.3% removal—compared to water-derived samples, which showed a maximum degradation of 52.1%. Anaerobic conditions, on the other hand, clearly slowed down degradation; the maximum degradation rates in water and soil samples were 43.7% and 11.1%, respectively. Although no clear linear relationship was found, the correlation between initial microbial populations and degradation performance revealed that higher counts of heterotrophic and oil-degrading bacteria generally enhanced biodegradation. Under anaerobic conditions, especially, persistent hydrocarbon peaks in both environments suggest the presence of recalcitrant heavy oil fractions such as polycyclic aromatic hydrocarbons. In conclusion, this study emphasizes the crucial roles microbial sources and oxygen availability play in maximizing bioremediation techniques for environments contaminated with heavy oil. Full article

The increasing global oil consumption has led to significant soil contamination by hydrocarbons, notably diesel-range hydrocarbons. Soil bioremediation through bacterial bioaugmentation is an alternative to increase the degradation of organic pollutants such as petroleum products. Bioremediation is a sustainable practice that contributes to the Sustainable Development Goals (SDGs) because it is environmentally friendly, reduces the impact of human activities, and avoids the use of invasive and destructive methods in soil restoration. This study examines the bioremediation potential of hydrocarbonoclastic bacteria isolated from soil close to areas with a risk of spills due to pipelines carrying hydrocarbons. Among the isolated strains, Arthrobacter globiformis, Pantoea agglomerans, and Nitratireductor soli exhibited hydrocarbonoclast activity, achieving diesel removal of up to 90% in short-chain alkanes and up to 60% in long-chain hydrocarbons. The results from in silico studies, which included molecular docking and molecular dynamics simulations, suggest that the diesel removal activity can be explained by the bioavailability of the linear alkanes and their affinity for alkane monooxygenase AlkB present in the studied microorganisms, since long-chain hydrocarbons had lower enzyme affinity and lower aqueous solubility. The correlation of the experimental results with the computational analysis allows for greater insight into the processes involved in the microbial degradation of hydrocarbons with varying chain lengths. Furthermore, this methodology establishes a cost-effective approximation tool for the evaluation of the feasibility of using different microorganisms in bioremediation processes. Full article

Considering the implications for the environment and human health, oil-contaminated soil generated in the petroleum industry requires treatment. Chemical cleaning represents an effective treatment approach for oil-contaminated soil and has attracted considerable attention. In this study, sodium d-gluconate (C₆H₁₁NaO₇), trisodium citrate (C₆H₅Na₃O₇), and L-arginine (C₆H₁₄N₄O₂) were employed as detergents to remove oil from oily sludge. The impacts of sludge (solid) concentration (C_S), types of detergents, temperature (T), and pH value on the deoiling efficiency (D_e) were systematically investigated. The results indicated that at a given detergent concentration (C_DG) and C_S, D_e followed the order C₆H₁₁NaO₇ > C₆H₅Na₃O₇ > C₆H₁₄N₄O₂. When C_S was 3.86 g·L⁻¹ and C_DG was 10.0 g·L⁻¹, sodium d-gluconate achieved a maximum D_e of approximately 85%. Additionally, at a fixed C_S, D_e decreased as the pH value increased, while it increased with increasing temperature. Interestingly, during the deoiling equilibrium, an obvious “solid effect” (or C_S−effect) was observed. The “solid effect” refers to the phenomenon where the oil distribution coefficient (K_D) changes with an increase in C_S. The observed C_S effect was described using the surface component activity (SCA) model. The values of the intrinsic distribution coefficient ($K_D^0$) and C_S−effect constant (γ), which are the model parameters of the SCA model, were derived from three detergent−sludge systems under different temperatures (T) and pH values. The strength of the C_S effect (or γ value) was found to be independent of detergent type and increased as T and pH value increased. This study broadens the application range of the SCA model and contributes to a deeper understanding of the adsorption and desorption behavior of oil droplets at the solid−liquid interface. Full article

Petroleum pollution has become a substantial challenge in soil ecology. The soil bacterial consortia play a major role in the biodegradation of petroleum hydrocarbons. The main objective of this study was to assess changes in bacterial composition and diversity in oil-contaminated dryland soils. The Illumina MiSeq high-throughput sequencing technique was used to study the bacterial diversity and structural change in hyper-arid oil-contaminated soil in the Arava Valley of Israel. The diversity and abundance of soil bacteria declined significantly following oil pollution. The dominant phyla in the petroleum-contaminated soils were Proteobacteria (~33% higher vs. control soil) and Patescibacteria (~2.5% higher vs. control soil), which are oil-associated and hydrocarbon-degrading bacteria. An opposite trend was found for the Actinobacteria (~8%), Chloroflexi (12%), Gemmatimonadetes (3%), and Planctomycetes (2%) phyla, with the lower abundances in contaminated soil vs. control soil. Investigation of long-term contaminated sites revealed significant genus-level taxonomic restructuring in soil bacterial communities. The most evident changes were observed in Mycobacterium, Alkanindiges, and uncultured bacterium-145, which showed marked abundance shifts between spill and control soils across decades. Particularly, hydrocarbon-degrading genera such as Pseudoxanthomonas demonstrated persistent dominance in contaminated sites. While some genera (e.g., Frigoribacterium, Leifsonia) declined over time, others—particularly Nocardioides and Streptomyces—exhibited substantial increases by 2014, suggesting potential ecological succession or adaptive selection. Minor but consistent changes were also detected in stress-tolerant genera like Blastococcus and Quadrisphaera. The effect of oil contamination on species diversity was greater at the 1975 site compared to the 2014 site. These patterns highlight the dynamic response of bacterial communities to chronic contamination, with implications for bioremediation and ecosystem recovery. The study results provide new insights into oil contamination-induced changes in soil bacterial community and may assist in designing appropriate biodegradation strategies to alleviate the impacts of oil contamination in drylands. Full article

The vegetation restoration of contaminated sites plays a critical role in ensuring the sustained stability and functional integrity of natural ecosystems. However, during the natural revegetation process, the variations in habitat conditions, bacterial community structure, and metabolic functions in aged, polluted soil are still unclear. In the present study, we investigated aged, polycyclic aromatic hydrocarbon (PAH)-polluted soils at closed, abandoned oil well sites from the Yellow River Delta. Using gene amplification and real-time qPCR methods, the abundance, taxonomy, and diversity characteristics of indigenous bacterial communities and functional bacteria carrying C12O genes in both vegetated soils and bare soils were investigated. The results show that natural revegetation significantly changes the physicochemical parameters, PAH content, and bacterial community structure of aged, PAH-polluted soils. When comparing the abundance and components of PAH-degrading bacterial communities in vegetated and bare soils, the PAH-degrading potential was revealed to be stimulated by vegetation communities. Through correlation analysis, dual stress from soil salinity and PAH contamination in bacterial communities was revealed to be mediated through alterations in the soil’s physicochemical properties by local vegetation. The network analysis revealed that bacterial communities in vegetated soils have higher network connectivity. These results elucidate the alterations in habitat conditions, bacterial components, and PAH-degrading communities following vegetation restoration, providing critical insights for optimizing ecological rehabilitation strategies in salinized and contaminated ecosystems. Full article

(1) Background: Polycyclic aromatic hydrocarbons (PAHs) are important components of petroleum and pose a serious threat to the soil environment of oil production well sites. Therefore, scientific risk thresholds and ecological risk assessment methods must be established for PAHs in petroleum-contaminated soils. (2) Methods: In this study, based on the environmental DNA (eDNA) method, the soil bacterial community was considered as a receptor to assess the ecological risks of PAH contamination in aged petroleum-polluted soils. A combination of the risk quotient and the equivalent toxicity factor was used to assess the ecological risk of PAHs. (3) Results: A dose–response curve was plotted to determine the 50% effective concentration (EC₅₀) of the total equivalent toxicity for 16 PAHs (∑TEQ_BaP) in petroleum-contaminated soils. Following the plot of the species sensitivity distribution (SSD) curve, the hazardous concentration for protecting 95% species values (HC₅) of petroleum hydrocarbons (TPHs), electrical conductivity (EC), and total equivalent toxicity of PAHs were calculated to be 892.1 μs·cm⁻¹, 149.9 mg·kg⁻¹, and 0.2601 mg·kg⁻¹, respectively. The regression models of the distribution factor (DF) and aging factor (AF) were defined as DF = −1.132 SOM + 0.033PAHs + 9.968 and AF = 242.518 SOM + 1256.029 lgpH + 0.024 EC − 1415.447. Following calibrations of the DF and AF, the value of HC₅ was determined as 0.1956 mg·kg⁻¹, which could be considered the risk threshold of the total toxicity of PAHs. The calibrated toxicity data distribution was consistent with that of the normal cumulative probability distribution model. The results showed that 50% of the aged petroleum-contaminated soils showed high-risk levels of bacterial communities exposed to PAHs. (4) Conclusions: This study provides a reference for deriving the ecological risk threshold of soil pollutants and explores alternative methods for the ecological risk assessment of PAHs at specific sites. Full article

The Clonostachys genus is a saprophytic soil microfungus (Ascomycota). It exhibits significant ecological adaptability and plays a crucial role in maintaining the balance of soil microorganisms. Species within this genus are natural antagonists of insects and nematodes, and they also combat phytopathogenic fungi through mycoparasitism. This process involves producing lytic enzymes and competing for space and nutrients. Clonostachys species are effective biocontrol agents in agriculture and have been utilized to manage pests affecting many high-value commercial crops, acting as a natural biopesticide. They inhabit plant tissues, boosting plant defenses and activating genes for water and nutrient uptake, enhancing plant performance. Additionally, they produce enzymes and bioactive metabolites with antimicrobial, antifungal, nematocidal, anticancer, and antioxidant properties. Clonostachys species can degrade plastic waste and remove hydrocarbons from crude oil-contaminated sites when functioning as endophytes, positioning Clonostachys as a promising candidate for reducing environmental pollution. There are still challenges and limitations, such as the continuous surveillance of the safety of Clonostachys species on plants, the establishment of commercial applications, formulation viability, and variability due to field conditions. These issues will have to be addressed. This review provides an overview of Clonostachys ecology, morphology, classification, and biotechnological applications, emphasizing its significance in various fields. Full article

Currently, increasing anthropogenic pressure and overexploitation expose soils to various forms of degradation, including contamination, erosion, and sealing. Soil contamination, primarily caused by industrial processes, agricultural practices (such as the use of pesticides and fertilizers), and improper waste disposal, poses significant risks to human health, biodiversity, and the environment. Common contaminants include heavy metals, mineral oils, petroleum-based hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons, and polycyclic aromatic hydrocarbons. Remediation methods for contaminated soils include physical, physicochemical, chemical or biological approaches. This review aims to specify these methods while comparing their effectiveness and applicability in different contamination scenarios. Biochemical methods, particularly phytoremediation, are emphasized for their sustainability, effectiveness, and suitability in arid and semiarid regions. These methods preserve soil quality and promote resource efficiency, waste reduction, and bioenergy production, aligning with sustainability principles and contributing to a circular economy. The integrated phytoremediation–bioenergy approaches reviewed provide sustainable and cost-efficient strategies for environmental decontamination and green development. Special attention is given to the use of lignin in bioremediation. This work contributes to the existing knowledge by outlining priorities for the selection of the most appropriate remediation techniques under diverse environmental conditions, providing a comprehensive overview for future developments. Full article

The rapid expansion of the petrochemical industry has led to significant environmental issues, including groundwater and soil contamination from hydrocarbon spills. This study investigates the movement and dispersion of hydrocarbon contaminants in the Rey industrial area in Tehran (Iran) using a two-dimensional finite element model. The results indicate that the oil plume exhibits slow migration, primarily due to low soil permeability and high hydrocarbon viscosity, leading to localized contamination. High-density pollution zones, such as TORC and REY7, are characterized by persistent hydrocarbon accumulation with minimal lateral migration. The findings emphasize the limited effectiveness of natural attenuation alone, highlighting the need for targeted remediation measures in high-density zones to accelerate contamination reduction. This study provides insights into the dynamics of hydrocarbon pollution and supports the development of effective remediation strategies. Full article

To address the environmental hazards posed by oil spills and the limitations of conventional hydrocarbon monitoring techniques, a cost-effective and user-friendly gas sensor system was developed for the real-time detection and quantification of hydrocarbon contaminants in soil. This system utilizes carbon black (CB)-filled poly(methyl methacrylate) (PMMA) and poly(vinyl chloride) (PVC) nanocomposites to create chemoresistive sensors. The CB-PMMA and CB-PVC composites were synthesized and deposited as thin films onto interdigitated electrodes, with their morphologies characterized using scanning electron microscopy. The composites, optimized at a composition of 10% w/w CB and 90% w/w polymer, exhibited a sensitive response to hydrocarbon vapors across a tested range from C₂₀ (99 ppmV) to C₈ (8750 ppmV). The sensor’s response mechanism is primarily attributed to the swelling-induced resistance change of the amorphous polymer matrix in hydrocarbon vapors. These findings demonstrate the potential use of CB–polymer composites as field-deployable gas sensors, providing a rapid and efficient alternative to traditional gas chromatography methods for monitoring soil remediation efforts and mitigating the environmental impact of oil contamination. Full article

Spills involving fuels and lubricating oils in industrial environments caused by the fueling of machines, inadequate storage and the washing of equipment are significant sources of environmental pollution, impacting soil and water bodies. Such incidents alter the microbiological, chemical and physical properties of affected environments. The use of biosurfactants is an effective option for the cleaning of storage tanks and the remediation of contaminated soils and effluents. The scope of this work was to assess the production and application of a Starmerella bombicola ATCC 22214 biosurfactant to remediate marine and terrestrial environment polluted by oil. The production of the biosurfactant was optimized in terms of carbon/nitrogen sources and culture conditions using flasks. The performance of the biosurfactant was tested in clayey soil, silty soil, and standard sand, as well as smooth surfaces and industrial effluents contaminated with oils (fuel oils B1 for thermal power generation, diesel, and motor oil). The ideal culture medium for the production of the biosurfactant contained 2% glucose and 5% glycerol, with agitation at 200 rpm, fermentation for 180 h and a 5% inoculum, resulting in a yield of 1.5 g/L. The biosurfactant had high emulsification indices (86.6% for motor oil and 51.7% for diesel) and exhibited good stability under different pH values, temperatures and concentrations of NaCl. The critical micelle concentration was 0.4 g/L, with a surface tension of 26.85 mN/m. In remediation tests, the biosurfactant enabled the removal of no less than 99% of motor oil from different types of soil. The results showed that the biosurfactant produced by Starmerella bombicola is a promising agent for the remediation of environments contaminated by oil derivatives, especially in industrial environments and for the treatment of oily effluents. Full article

Oil leakage during the processes of extraction, storage, and transportation poses a significant challenge due to the complex nature of pollution caused by frequent fluctuations in groundwater levels and variations in the water–oil interface. To effectively identify and monitor the position of the water–oil interface and displacement processes, geophysical methods have proven to be an efficient approach. This study utilizes electrical resistivity measurements to analyze changes in medium resistivity during water–oil displacement, enabling simulation of the spatial relationship between groundwater levels and petroleum contaminants based on resistivity characteristics and natural potential responses. After analysis, the following conclusions can be drawn: (1) During the water displacement process, when water forms a connected flow channel between sand and gravel, the resistivity decreases abruptly. Conversely, during oil displacement by water, when oil fills soil pores and creates a high-resistance conductive path, the resistivity increases abruptly. (2) Changes in resistivity are determined by the position of the water–oil interface. By observing characteristic changes in resistivity, it is possible to verify whether soil is undergoing water–oil displacement. (3) The direction of displacement significantly affects changes in resistivity for all three media involved due to gravity effects during water displacement by the oil process. (4) Resistance values during the water–oil displacement process are directly influenced by the size of sand particles used in experiments. Full article

Per- and polyfluoroalkyl substances (PFASs) are a class of manufactured organic chemicals that are widely employed for their heat-, oil-, and water-resistant properties. Studies have shown that the bioaccumulation of PFASs in living organisms and their related health effects are sufficient for classifying them as a group of toxicants worthy of great concern and further study. While PFASs travel through the air and soil, their contamination of water pathways proves to be the most common route for exposure. We analyzed PFASs from three different wastewater treatment plants (WWTPs) throughout Arizona to show that, despite treatment efforts, they persist as contaminants in water sources. Using U.S. Environmental Protection Agency method 1633, seasonally obtained field samples were prepared for analysis through liquid chromatography–tandem mass spectrometry. A total of 24 samples were taken at different stages of the treatment process to assess the proficiency of the removal processes during remediation. Duplicate samples were each taken from Tucson’s WWTP and Flagstaff’s WWTP before and after chlorination, and from three sites in Yuma County, upstream effluent, downstream effluent, and WWTP, before chlorination. From the samples obtained in Yuma, perfluorooctanesulfonic acid, perfluorooctanoic acid, and perfluorohexanesulfonic acid were detected but at levels below their limits of quantification. PFBS was detected at the Yuma and Tucson WWTP at levels up to 4.52 ng/L and 73.53 ng/L, respectively. The samples obtained from Flagstaff’s WWTP were below the instrument level of detection and, therefore, characterized as non-detects. Full article