Phytotoxicity of petroleum hydrocarbons: Sources, impacts and remediation strategies.

The contamination of soil with total petroleum hydrocarbons (TPH) may result in dramatic consequences and needs great attention, as soil rehabilitation would need more effort from a sustainability perspective. However, there is still no known general method since the remediation technology is strictly site-specific. Adaptive biological system dynamics can play a key role in understanding and addressing the potential of situ-specific biological combinations for soil pollutants removal. The potential worst-case of TPH contamination reflects soil affected by heavy industrial activities, such as oil refineries. Therefore, the experimental trial was conducted on a 2,000 m2 area from a contaminated site located in northern Italy. We evaluated the remediation potential over time (270 days) assessing (i) the phytoremediation efficiency of two species of Poaceae (Festuca arundinacea Schreb. and Dactylis glomerata L.) and two species of Fabaceae (Medicago sativa L. and Lotus corniculatus L.) and (ii) the role of the indigenous bacteria flora and endo-mycorrhizae consortium addition in plant growth promotion. We also induced resistance to contamination stress in a field experiment. Thirty-three indigenous bacteria selected from the contaminated soils showed marked plant growth promotion. Moreover, functional metagenomics confirmed the metabolic capability of hydrocarbon-degrading microorganisms living in the polluted soil. Our data showed that soil enzymatic activities increased with hydrocarbon degradation rate after 60 days. Both Poaceae and Fabaceae resulted in remarkable remediation potential. Stress markers and antioxidant activity indicated that the selected plant species generally need some time to adapt to TPH stress. In conclusion, our evaluation implied both the rhizosphere effects and functional features of the plant and suggested that plants should (i) have marked tolerance to specific contaminants, (ii) be characterized by an extensive root system, and (iii) be susceptible to arbuscular mycorrhizal fungi (AMF) infection.

/pdf/plant-soil-microbiota-combination-for-the-removal-of-total-4ubc7mh5hx.pdf

Plant-Soil-Microbiota Combination for the Removal of Total Petroleum Hydrocarbons (TPH): An In-Field Experiment.

Advanced switchable molecules and materials have shown great potential in numerous applications. These novel materials can express different states of physicochemical properties as controlled by a designated stimulus, such that the processing condition can always be maintained in an optimized manner for improved efficiency and sustainability throughout the whole process. Herein, the recent advances in switchable molecules/materials in oil recovery and oily waste cleanup are reviewed. Oil recovery and oily waste cleanup are of critical importance to the industry and environment. Switchable materials can be designed with various types of switchable properties, including i) switchable interfacial activity, ii) switchable viscosity, iii) switchable solvent, and iv) switchable wettability. The materials can then be deployed into the most suitable applications according to the process requirements. An in-depth discussion about the fundamental basis of the design considerations is provided for each type of switchable material, followed by details about their performances and challenges in the applications. Finally, an outlook for the development of next-generation switchable molecules/materials is discussed.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/advs.202004082

Advanced Switchable Molecules and Materials for Oil Recovery and Oily Waste Cleanup

Soil microbial community structure is altered by petroleum contamination in response to compound toxicity and degradation. Understanding the relation between petroleum contamination and soil microbial community structure is crucial to determine the amenability of contaminated soils to bacterial- and fungal-aided remediation. To understand how petroleum contamination and soil physicochemical properties jointly shaped the microbial structure of soils from different oilfields, high-throughput sequencing of 16S and ITS amplicons were used to evaluate the shifts of microbial communities in the petroleum-contaminated soils in Ughelli East (UE), Utorogu (UT), and Ughelli West (UW) oilfields located in Delta State, Nigeria. The results showed 1515 bacteria and 919 fungal average OTU number, and community richness and diversity, trending as AL > UT > UW > UE and AL > UW > UT > UE for bacteria, and AL > UW > UT > UE and UW > UT > AL > UE for fungi, respectively. The bacterial taxa KCM-B-112, unclassified Saccharibacteria, unclassified Rhizobiales, Desulfurellaceae, and Acidobacteriaceae and fungal Trichocomaceae, unclassified Ascomycota, unclassified Sporidiobolales, and unclassified Fungi were found to be the dominant families in petroleum-contaminated soils. Redundancy analysis (RDA) and Spearman’s correlation analysis revealed that total carbon (TC), electric conductivity (EC), pH, and moisture content (MO) were the major drivers of bacterial and fungal communities, respectively. Gas chromatography-mass spectrophotometer (GC-MS) analysis exhibited that the differences in C7–C10, C11–C16, and C12–C29 compounds in the crude oil composition and soil MO content jointly constituted the microbial community variance among the contaminated soils. This study revealed the bacterial and fungal communities responsible for the biodegradation of petroleum contamination from these oilfields, which could serve as biomarkers to monitor oil spill site restoration within these areas. Further studies on these contaminated sites could offer useful insights into other contributing factors such as heavy metals.

Petroleum contamination significantly changes soil microbial communities in three oilfield locations in Delta State, Nigeria

Differences in geological conditions have reshaped the structure and diversity of microbial communities in oily soils.

Oil contamination causes serious geoenvironmental concern and adversely affects the soil environment due to the release of toxic by-products. Hence, the aim of the study was to investigate the influence of oil contamination on soil physical and chemical properties and phytoremediation as a treatment option based on field studies conducted for analyzing significant parameters. The sites selected were near National Institute of Technology, Surathkal, Karnataka (site-1), and another is close to the oil refinery (Kuthethur, Karnataka, India, as site-2). Phytoremediation of oil-contaminated samples was carried out by Chromolaena odorata. The evaluation of soil physical and chemical properties includes field and laboratory tests. A pumping test was conducted to estimate aquifer parameters in the field. The hydraulic conductivity for field soil sample (unsaturated condition) is carried out by a filter paper test. Laboratory tests to evaluate physical and chemical parameters include total petroleum hydrocarbons of contaminated (crude oil varying from 0 to 10% at an interval of 2%) and uncontaminated samples and plant parameters. Characterization of contaminated and uncontaminated soil sample was performed by Fourier transform infrared (FTIR) spectroscopy. The results obtained reveal that physical properties of soil (moisture content, liquid and plastic limit) got affected due to oil contamination. Relative hydraulic conductivity was established as 0.46 (uncontaminated) and 0.57 (contaminated) for soil samples and led to the conclusion that hydraulic conductivity was drop down by 10% due to oil contamination. Total petroleum hydrocarbon analysis reveals that the uptake/presence of hydrocarbons by showing increased concentration in contaminated soils (5% and 10%) by the plant species. This is further confirmed by FTIR results. The TPH concentrations in the contaminated soils were reduced up to 50–60% and also showed better plant growth after 7 weeks of transplantation. Hence, considered plant species possess high potential for degrading oil contaminated in the soil.

/pdf/investigation-of-physical-and-chemical-characteristics-on-3bmjfo43g2.pdf

J. Purna Chandra Rao

Papers

Investigation of physical and chemical characteristics on soil due to crude oil contamination and its remediation