Search Results (20)

The influence of petroleum hydrocarbons (PHCs) on the transport and transformation of heavy metals may limit bioremediation efficiency. The mechanisms by which PHC degradation intermediates control heavy metal distribution in calcareous soils from karst areas require further exploration. This study systematically investigated how compositional changes in diesel fuel during aging regulated the fate of Cd and Pb in calcareous soils. The results demonstrated that the low-molecular-weight fractions of diesel fuel (C₁₀−C₁₆) were preferentially degraded. This degradation process altered zeta potential, cation exchange capacity (CEC), and pH, thereby promoting Cd stabilization through electrostatic attraction and speciation transformation. Particularly, reducible Cd content showed a strong positive correlation with C₁₆ content (r = 0.88, p < 0.05). Furthermore, the degradation of C₁₀−C₁₆ fractions caused Pb transformation from residual to bioavailable fractions by stimulating microbial activity. Residual Pb content was positively correlated with C₁₀−C₁₆ fractions (r = 0.55, p < 0.05). Notably, dissolved organic matter (DOM) and CaCO₃ content in calcareous soils enhanced Cd and Pb adsorption, thereby weakening the interactions between these metals and C₁₀−C₁₆ fractions. Consequently, multiple linear regression (MLR) models relying exclusively on C₁₀−C₁₆ degradation parameters showed poor fitting coefficients for Cd/Pb mobility. The present work provides scientific guidance for heavy metal bioremediation in calcareous soils. Full article

Rhizodegradation enhances pollutant degradation through plant–microbe interactions in the rhizosphere. Plant roots provide a colonisation surface and root exudates that promote microbial abundance and activity, facilitating organic pollutant breakdown via direct microbial degradation and co-metabolism. This study assessed the rhizodegradation of weathered petroleum hydrocarbons (PHCs) in heavy metal co-contaminated soil in a microcosm-scale pot trial. Treatments included Sinapis alba, Lolium perenne, a L. perenne + Trifolium repens mix, and Cichorium intybus, alongside a non-planted control. After 14 weeks, PHC concentrations were analysed via gas chromatography, and rhizosphere microbial communities were characterised through sequencing. Sinapis alba achieved the highest PHC degradation (68%), significantly exceeding the non-planted control (p < 0.05, Kruskal–Wallis test). Hydrocarbon-degrading bacteria, including KCM-B-112, C1-B045, Hydrogenophaga, unclassified Saccharimonadales sp., and Pedobacter, were enriched in the rhizosphere, with the uncultured clade mle1-27 potentially contributing indirectly. Metals analysis of plant tissues showed that mustard could accumulate copper more than lead and zinc, despite higher concentrations of zinc and lead in the soil. These results highlight the potential of S. alba for rhizoremediation in PHC–heavy metal co-contaminated soils. Full article

A quantitative and qualitative assessment using molecular markers derived from compound-specific indices for indicating groundwater impacted by petroleum spills in an oil field was recently undertaken and demonstrated serious contamination, with both high total petroleum hydrocarbons (TPH) (3.68–7.32 mg/L) and hazardous compounds in the groundwater. A petroleum source was identified, and the analysis revealed a decreasing trend of fresh petroleum input, along with groundwater advection and an increasing trend of biodegradation potential at locations farther from the source. This was confirmed via microbial analysis with both biodegrading microorganisms and diversity indices (Shannon, Simpson, and Pielou) and the principal component analysis (PCA) modeling approach, which classified the field samples into three types according to the distribution correlations between different organic compounds. Biodegradation was believed to be the dominant sink of hydrocarbons due to the increasing Pr/C17 and Ph/C18 values with seasonal changes. Raised temperatures activated the microbial degradation process; specifically, low-weight hydrocarbons degraded more rapidly than high-weight hydrocarbons, resulting in the accumulation of an unresolved complex mixture of bioproducts at locations that were farther away. Spatially, the Pr/C17 and Ph/C18 values increased from the upstream to the downstream areas, showing substantial biodegradation. The relationships between the molecular markers and chemical indices were quantified via canonical correlation analysis (CCA) to visually explain the interactive reaction processes. It was also demonstrated that the biodegradation of petroleum organics can be characterized by the consumption of dissolved oxygen and a decreasing Pr/Ph ratio, due to system reduction. These results demonstrate that compound-specific molecular markers, coupled with biochemical parameters, can effectively support a better understanding and effective fingerprinting of the fate and transport of petroleum organic contaminants, thus offering valuable technical support for a cost-effective remediation strategy. Full article

Immobilized microbial materials can effectively remove pollutants from surface water, and a biochar/clay composite particle (BCCP) material is prepared with immobilized Flavobacterium mizutaii sp. and Aquamicrobium sp. to remove ammonia nitrogen (NH₄⁺–N) and petroleum hydrocarbons (PHCs). The results indicated that the optimal ratios of biochar, Na₂SiO₃ and NaHCO₃ were 15%, 3%, and 3%, and the adsorption process was found to be better described with the pseudo-second-order kinetic equation. The individual immobilization of Flavobacterium mizutaii sp. and Aquamicrobium sp. with sodium alginate–polyvinyl alcohol (PVA + SA) achieved 80% and 90% removal efficiencies for NH₄⁺–N and PHCs at the 10th d. The composite immobilization of two efficient bacteria could degrade 82.48% NH₄⁺–N and 74.62% PHCs. In addition, immobilization relieved the effects of temperature and salinity. This study can provide guidance for the application of immobilized microbial composite materials in natural water environments. Full article

The present work aimed to develop and investigate microbial consortia for petroleum hydrocarbons (PHCs) detoxification and plant growth improvement in hydrocarbons-contaminated soil. Here, we isolated several bacteria from PHCs-contaminated soils to make bacterial consortia and two of the best consortia were tested in a pot experiment to evaluate their potential for PHCs removal and chickpea growth promotion in PHCs-contaminated soil. Results demonstrated that the PHCs exerted considerable phytotoxic effects on chickpea growth and physiology by causing a 13–29% and a 12–43% reduction in agronomic and physiological traits, respectively. However, in the presence of bacterial consortia, the phytotoxicity of PHCs to chickpea plants was minimized, resulting in a 7.0–24% and a 6.0–35% increase in agronomic and physiological traits, respectively over un-inoculated controls. Bacterial consortia also boosted nutrient uptake and the antioxidant mechanism of the chickpea. In addition, chickpea plants alone phytoremediated 52% of initial PHCs concentration. The addition of bacterial consortia in the presence of chickpea plants could remove 74–80% of the initial PHCs concentration in soil. Based on our research findings, we suggest that the use of multi-trait bacterial consortia could be a sustainable and environmentally friendly strategy for PHCs remediation and plant growth promotion in hydrocarbons in contaminated soil. Full article

Phytoremediation and the use of suitable amendments are well-known technologies for the mitigation of petroleum hydrocarbon (PHC) contaminations in terrestrial ecosystems. Our study is aimed at combining these two approaches to maximize their favorable effects. To this purpose, Helichrysum microphyllum subsp. tyrrhenicum, a Mediterranean shrub growing on sandy and semiarid soils, was selected. The weathered PHC-polluted matrix (3.3 ± 0.8 g kg⁻¹ dry weight) from a disused industrial site was employed as the cultivation substrate with (WCAM) or without (UNAM) the addition and mixing of wood chips. Under the greenhouse conditions, the species showed a survival rate higher than 90% in the UNAM while the amendment administration restored the totality of the plant survival. At the end of the greenhouse test (nine months), the treatment with the wood chips significantly increased the moisture, dehydrogenase activity and abundance of the microbial populations of the PHC degraders in the substrate. Cogently, the residual amount of PHCs was significantly lower in the UNAM (3–92% of the initial quantity) than in the WCAM (3–14% of the initial quantity). Moreover, the crown diameter was significantly higher in the WCAM plants. Overall, the results establish the combined technology as a novel approach for landscaping and the bioremediation of sites chronically injured by PHC-weathered contaminations. Full article

Polycyclic aromatic hydrocarbons (PAHs), as the main components of petroleum hydrocarbons (PHCs), are carcinogenic organic pollutants that occur widely in the atmospheric environment with increasing concentration. Moreover, PAHs are widespread all over the world due to their high volatility and long-range transport potential. The monitoring of atmospheric PAHs is often limited by working conditions, especially around oil field operation areas and other industrial areas. Mosses (Bryophyta), the most sensitive atmosphere pollution indicators, can be easily collected and have been used to monitor atmospheric pollutants including PAHs. Thus, characteristics and influencing factors of mosses’ absorption and accumulation of PAHs in the atmosphere were discussed, and the application of mosses in the biomonitoring of atmospheric PAHs were summarized. Biomonitoring mosses include Dicranum scoparium, Hypnum cupressiforme, Thamnobryum alopecurum, Thuidium tamariscinum, Hylocomium splendens, Pleurozium scheberi, etc. Currently, the main methods for monitoring PAHs by mosses are biomonitoring with the chemical analysis method, the index of atmospheric purity (IAP) method, the ecological survey method, and the Moss-bag technique. Biomonitoring of atmospheric PAHs using mosses has a relatively wide range of prospects. Full article

Leaks from accidents or damage to pipelines that transport liquid petroleum hydrocarbons (PHC) such as gasoline and diesel are harmful to the environment as well as to human health, and may be hard to detect by inspection mechanisms alone when they occur in small volumes or persistently. In the present study, we aim to identify spectral anomalies in two plant species (Brachiaria brizantha and Neonotonia wightii) linked to contamination effects at different developmental phases of these plants. To do so, we used spectroscopy and remote sensing approaches to detect small gasoline and diesel leaks by observing the damage caused to the vegetation that covers simulated pipelines. We performed a contamination test before and after planting using gasoline and diesel volumes that varied between 2 and 16 L/m³ soil, in two experimental designs: (i) single contamination before planting, and (ii) periodic contaminations after planting and during plant growth. We collected the reflectance spectra from 35 to approximately 100 days after planting. We then compared the absorption features positioned from the visible spectral range to the shortwave infrared and the spectral parameters in the red edge range of the contaminated plants to the healthy plants, thus confirming the visual and biochemical changes verified in the contaminated plants. Despite the complexity in the indirect identification of soil contamination by PHCs, since it involves different stages of plant development, the results were promising and can be used as a reference for methods of indirect detection from UAVs (Unmanned Aerial Vehicles), airplanes, and satellites equipped with hyperspectral sensors. Full article

The increasing demand for petroleum products generates needs for innovative and reliable methods for cleaning up crude oil spills. Annually, several oil spills occur around the world, which brings numerous ecological and environmental disasters on the surface of deep seawaters like oceans. Biological and physico-chemical remediation technologies can be efficient in terms of spill cleanup and microorganisms—mainly bacteria—are the main ones responsible for petroleum hydrocarbons (PHCs) degradation such as crude oil. Currently, biodegradation is considered as one of the most sustainable and efficient techniques for the removal of PHCs. However, environmental factors associated with the functioning and performance of microorganisms involved in hydrocarbon-degradation have remained relatively unclear. This has limited our understanding on how to select and inoculate microorganisms within technologies of cleaning and to optimize physico-chemical remediation and degradation methods. This review article presents the latest discoveries in bioremediation techniques such as biostimulation, bioaugmentation, and biosurfactants as well as immobilization strategies for increasing the efficiency. Besides, environmental affecting factors and microbial strains engaged in bioremediation and biodegradation of PHCs in marines are discussed. Full article

Soil contamination with petroleum hydrocarbons (PHCs) has become a global concern and has resulted from the intensification of industrial activities. This has created a serious environmental issue; therefore, there is a need to find solutions, including application of efficient remediation technologies or improvement of current techniques. Rhizoremediation is a green technology that has received global attention as a cost-effective and possibly efficient remediation technique for PHC-polluted soil. Rhizoremediation refers to the use of plants and their associated microbiota to clean up contaminated soils, where plant roots stimulate soil microbes to mineralize organic contaminants to H₂O and CO₂. However, this multipartite interaction is complicated because many biotic and abiotic factors can influence microbial processes in the soil, making the efficiency of rhizoremediation unpredictable. This review reports the current knowledge of rhizoremediation approaches that can accelerate the remediation of PHC-contaminated soil. Recent approaches discussed in this review include (1) selecting plants with desired characteristics suitable for rhizoremediation; (2) exploiting and manipulating the plant microbiome by using inoculants containing plant growth-promoting rhizobacteria (PGPR) or hydrocarbon-degrading microbes, or a combination of both types of organisms; (3) enhancing the understanding of how the host–plant assembles a beneficial microbiome, and how it functions, under pollutant stress. A better understanding of plant–microbiome interactions could lead to successful use of rhizoremediation for PHC-contaminated soil in the future. Full article

Petroleum hydrocarbons (PHCs) are one of the most widespread and heterogeneous organic contaminants affecting marine ecosystems. The contamination of marine sediments or coastal areas by PHCs represents a major threat for the ecosystem and human health, calling for urgent, effective, and sustainable remediation solutions. Aside from some physical and chemical treatments that have been established over the years for marine sediment reclamation, bioremediation approaches based on the use of microorganisms are gaining increasing attention for their eco-compatibility, and lower costs. In this work, we review current knowledge concerning the bioremediation of PHCs in marine systems, presenting a synthesis of the most effective microbial taxa (i.e., bacteria, fungi, and microalgae) identified so far for hydrocarbon removal. We also discuss the challenges offered by innovative molecular approaches for the design of effective reclamation strategies based on these three microbial components of marine sediments contaminated by hydrocarbons. Full article

The soil samples were taken from the site of a former oil products depot from an industrial area (Romania). The soil samples taken were analyzed from a physical and chemical point of view: texture, pH, soil micronutrient content, metals concentration and petroleum hydrocarbon concentration (PHCs). The soil contaminated with total petroleum hydrocarbon (TPH (4280 mg kg⁻¹) was disposed in the form of a pile (L × W × H: 3000 × 1400 × 500 mm). Experiments on a pilot-scale were conducted over 12 weeks at constant pH (7.5–8), temperature (22–32 °C), nutrient contents C/N/P ratio 100/10/1, soil aeration time (8 h/day) and moisture (30%). Samples were taken every two weeks for the monitoring of the TPH and the microorganisms content. During the experiment, microorganisms were added (Pseudomonas and Bacillus) every two weeks. Results of the analyses regarding the concentration of PHCs were revealed a linear decrease of the concentration of PHCs after only two weeks of treatment. This decrease in concentration was also achieved in the following weeks. Following the analysis performed on the model at the pilot scale regarding the depollution process, it can be concluded that a soil contaminated with petroleum hydrocarbons can be efficiently depolluted by performing an aeration of 8 h/day, adding microorganisms Pseudomonas and Bacillus to ensure the conditions for increasing in the total number of germs (colony forming units–CFU) from 151 × 10⁵ to 213 × 10⁷ CFU g⁻¹ soil, after 12 weeks of soil treatment—the depollution efficiency achieved is 83%. Full article

The Salix genus includes shrub species that are widely used in phytoremediation and various other phytotechnologies due to their advantageous characteristics, such as a high evapotranspiration (ET) rate, in particular when cultivated in short rotation intensive culture (SRIC). Observations made in past field studies suggest that ET and its impact on soil hydrology can also lead to increases in soil pollutant concentrations near shrubs. To investigate this, sections of a mature willow plantation (seven years old) were cut to eliminate transpiration (Cut treatment). Soil concentrations of polychlorinated biphenyls (PCBs), aliphatic compounds C10–C50, polycyclic aromatic hydrocarbons (PAHs) and five trace elements (Cd, Cr, Cu, Ni and Zn) were compared between the Cut and the uncut plots (Salix miyabeana ‘SX61’). Over 24 months, the results clearly show that removal of the willow shrubs limited the contaminants’ increase in the soil surface, as observed for C10–C50 and of 10 PAHs under the Salix treatment. This finding strongly reinforces a hypothesis that SRIC of willows may facilitate the migration of contaminants towards their roots, thus increasing their concentration in the surrounding soil. Such a “pumping effect” in a high-density willow crop is a prominent characteristic specific to field studies that can lead to counterintuitive results. Although apparent increases of contaminant concentrations contradict the purification benefits usually pursued in phytoremediation, the possibility of active phytoextraction and rhizodegradation is not excluded. Moreover, increases of pollutant concentrations under shrubs following migration suggest that decreases would consequently occur at the source points. Some reflections on interpreting field work results are provided. Full article

For sustainable soil management, there is an increasing demand for soil quality, resilience, and health assessment. After remediation of petroleum hydrocarbon (PHC)-contaminated soils, changes in the physicochemical and ecological characteristics of the soil were investigated. Two kinds of remediation technologies were applied to contaminated soils: land farming (LF) and high temperature thermal desorption (HTTD). As a result of total petroleum hydrocarbons (TPH), PHC-contaminated soils were efficiently remediated by LF and HTTD. The soil health could not be completely recovered after the removal of pollutants due to adverse changes in the soil properties, especially in soil enzyme activities. Therefore, monitoring is necessary for accurate estimation of soil ecotoxicity and effective remediation, and additional soil management, such as fertilizer application or organic amendments, is needed to restore soil heath. In the case of HTTD, soil ecological properties are severely changed during the remediation process. The decision to reuse or recycle remediated soils should reflect changes in soil quality. HTTD is a harsh remediation method that results in deterioration of soil fertility and ecological functions. Alternatives, such as low-temperature thermal desorption or additional soil management using fertilizer or organic amendments, for example, are needed. Full article

Petroleum hydrocarbon (PHC) contamination of soil is a widespread global environmental concern due to the persistence and recalcitrant nature of PHCs. The PHCs are highly toxic and their removal from the terrestrial ecosystem is necessary to maintain soil as well as human health. Here, a pot experiment was performed to examine the impact of Enterobacter sp. MN17 and biochar addition on the growth of mungbean plants and PHCs removal from diesel-polluted soil. For this purpose, soil was contaminated artificially with diesel to achieve a final concentration of 5000 mg kg⁻¹. Untreated and Enterobacter sp. MN17 treated mungbean seeds were sown in pots. Sugarcane bagasse biochar was applied as an amendment in respective pots along with the recommended levels of essential nutrients. Results showed that PHCs significantly suppressed the seedling emergence as well as agronomic and physiological attributes of mungbean as compared to un-contaminated controls. However, the co-application of Enterobacter sp. MN17 and biochar significantly reduced the phytotoxicity of PHCs to mungbean plants and effectively increased the seedling emergence, shoot and root length, shoot fresh and dry biomass, root fresh and dry biomass of plants up to 24%, 54%, 52%, 52%, 54%, 55% and 60%, respectively as compared to controls. Similarly, 30%, 57%, 64%, 36% and 57% increase in chlorophylls contents, transpiration rate, stomatal conductance, sub-stomatal conductance, and photosynthetic rate, respectively were observed in their combined application as compared to respective controls. Furthermore, the co-addition of biochar and Enterobacter sp. MN17 could remove 69% and 85% higher PHCs from unplanted and planted pots, respectively, than that of their respective controls. Our results suggest that the co-application of biochar and Enterobacter sp. MN17 may be useful in enhancing plant growth and eliminating PHCs from contaminated soil. Full article