Pyrene In Soil Research Articles

Enzymatic bioremediation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil: a study on the recombinant laccase TVL

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) are pervasive and persistent pollutants in contaminated soil, posing a severe health and environmental threat. Enzymatic bioremediation presents a viable solution for the remediation of PAH-contaminated soil. In this study, a recombinant laccase with the encoding gene originating from Trametes villosa and recombinantly expressed in Aspergillus oryzae, designated as TVL, was discovered to possess strong PAH reduction capabilities. The specific enzyme activity of TVL was 73485 and 5102 LAMU/g enzyme protein at pH 5.0/7.0 and 37°C. Furthermore, it exhibited significant benzo[a]pyrene degradation, with 100% and 90.48% degradation at pH 5.0/7.0 after 24 h in the liquid phase. The degradation process of benzo[a]pyrene in soil was thoroughly investigated. Optimal conditions were identified as 15 mg/g NK-BSoil-3 and 1.35 mg/g HBT, resulting in a removal rate of 37.54% within 7 days when 0.01 U/g of TVL was applied. The potential mechanisms were investigated using molecular docking simulation. The binding energy between benzo[a]pyrene and TVL protein is notably robust, suggesting a higher propensity for enzyme binding. The TVL protein pocket contains nine amino acids that can interact most strongly with benzo[a]pyrene. Consequently, the recombinant laccase TVL holds considerable practical significance in bioremediation.

Removal of benzo[a]pyrene from the soil by adsorption coupled with degradation on saponin-modified bentonite immobilized crude enzymes

Bentonite is a non-metallic mineral with montmorillonite as the main component. It is an environmentally friendly mineral material with large reserves, wide distribution, and low price. Bentonite can be easily modified organically using the surfactant saponin to obtain saponin-modified bentonite (Sap-BT). This study investigates the immobilization of crude enzymes obtained from Trametes versicolor by physical adsorption with Sap-BT. Thus, saponin-modified bentonite immobilized crude enzymes (CE-Sap-BT) were developed to remove benzo[a]pyrene. Immobilization improves the stability of free enzymes. CE-Sap-BT can maintain more than 80% of activity at 45 °C and after storage for 15 d. Additionally, CE-Sap-BT exhibited a high removal rate of benzo[a]pyrene in soil, with 65.69% after 7 d in highly contaminated allotment soil and 52.90% after 6 d in actual soil contaminated with a low concentration of benzo[a]pyrene at a very low laccase dosage (0.1 U/3 g soil). The high catalytic and removal performance of CE-Sap-BT in contaminated sites showed more excellent practical application value.

Enhanced biodegradation of benzo[a]pyrene with Trametes versicolor stimulated by citric acid.

Polycyclic aromatic hydrocarbons (PAHs) are a class of persistent organic pollutants with carcinogenic, mutagenic and teratogenic effects. The white-rot fungi in the fungal group have significant degradation ability for high molecular weight organic pollutants. However, exogenous fungi are easily antagonized by indigenous microorganisms. Low molecular weight organic acids, a small molecular organic matter secreted by plants, can provide carbon sources for soil microorganisms. Combining organic acids with white rot fungi may improve the nutritional environment of fungi. In this study, immobilized Trametes versicolor was used to degrade benzo[a]pyrene in soil, and its effect on removing benzo[a]pyrene in soil mediated by different low molecular weight organic acids was investigated. The results showed that when the degradation was 35days, the removal effect of the experimental group with citric acid was the best, reaching 43.7%. The degradation effect of Trametes versicolor on benzo[a]pyrene was further investigated in the liquid medium when citric acid was added, and the effects of citric acid on the biomass, extracellular protein concentration and laccase activity of Trametes versicolor were investigated by controlling different concentrations of citric acid. In general, citric acid can act as a carbon source for Trametes versicolor and promote its extracellular protein secretion and laccase activity, thereby accelerating the mineralization of benzo[a]pyrene by Trametes versicolor. Therefore, citric acid can be used as a biostimulant in the remediation of PAHs contaminated soil with Trametes versicolor.

Incorporation of N-doped biochar into submicron zero-valent iron for efficient peroxydisulfate activation in soil remediation: Performance and mechanism

The development of strategic methods to enhance the catalytic reactivity and electron efficiency of biochar-modified zero-valent iron (BC-ZVI) via mechanochemistry is highly important and desirable for the use of peroxydisulfate-based advanced oxidation processes (PDS-AOPs) in soil remediation. Herein, novel amphiphilic ball-milled N-doped biochar-ZVI composites (NBC-ZVIbm) were fabricated to activate PDS for efficient pyrene degradation in soil. The N-doped site- and alloying heterojunction-induced surface charge redistribution, directional electron transfer, and amphiphilicity of NBC-ZVIbm were verified, all of which improved the interactions among NBC-ZVIbm, PDS and pyrene. Specifically, NBC incorporation optimized PDS oxidation and pyrene adsorption on NBC-ZVIbm, forming a reaction center that efficiently accelerated the reaction. As a result, 95.5 % of 98.3 mg/kg pyrene in soil was degraded by NBC-ZVIbm/PDS within 7 d, which was 2.3 and 1.5 times greater than that of ball-milled ZVI and BC-ZVIbm, respectively; additionally, the electron efficiency of this process increased to 85.2 %. Characterization of the reaction process suggested that NBC incorporation induced directional electron transfer from ZVI to NBC for PDS activation and SO4•- generation. Subsequently, the amphiphilicity of NBC-ZVIbm promoted soil phase-pyrene desorption and migration, thereby increasing pyrene degradation. This NBC-incorporation method provides a strategy for constructing highly efficient ZVI-based catalysts for the use of PDS-AOPs in soil remediation.

Superefficient non-radical degradation of benzo[a]pyrene in soil by Fe-biochar composites activating persulfate

Efficient decomposition of organic pollutants in complex soil environments through non-radical pathways is vital but challenging. Herein, biochar supported nZVI (nZVI@BC800) fabricated by carbothermal reduction method was prepared for persulfate activation, exhibiting ultrafast degradation efficiency of benzo[a]pyrene of 71.80 % within 5 min with excellent adaptability to wide pH range of 3.0–9.0 and high anti-interference capacity to coexisting substances in soil. In nZVI@BC800/persulfate system, non-radical pathways including singlet oxygen (1O2) and electron transfer made dominant contributions to benzo[a]pyrene degradation. 1O2 could be produced not only by the reaction between C = O on BC800 and persulfate, but also via the transformation of O2∙- and ∙OH. On the other hand, biochar as an electron shuttle could accelerate electron transfer from benzo[a]pyrene to persulfate adsorbed on the catalyst. Additionally, possible degradation pathways of benzo[a]pyrene in nZVI@BC800/persulfate system were inferred through GC–MS and DFT calculations. Furthermore, the system could modulate the soil microbial community to further improve plant stress resistance. Therefore, this study provided a promising strategy via developing carbon-supported iron catalyst for carrying out persulfate-based non-radical pathways to remediate organic-polluted soil.

Determination of soil environment criteria for ecological safety of benzo[a]pyrene in soil based on the species sensitivity distribution approach

Benzo[a]pyrene (BaP) is a highly carcinogenic organic pollutant. Its distinct toxic effects have raised significant concerns among regulators and researchers. However, the absence of established soil environmental criteria for ecological safety of BaP has led to a lack of evidence in the current risk assessment for soil ecological security. To address this gap, we conducted a comprehensive study to investigate the toxicity of BaP using multiple soil organisms, including rice, wheat, lettuce, rape, cucumber, tomato, leonurus, and earthworm. The toxicity data obtained were applied to the species sensitivity distribution (SSD) approach, and the soil environment criteria for ecological safety of BaP under different land use types were derived. The soil environmental criteria for ecological safety of BaP were estimated to be 1.07 (Natural reserve and agricultural land), 1.63 (Parkland), 3.84 (Residential land) and 6.46 (Commercial service and industrial land) mg·kg−1, respectively. This study is the first to conduct toxicity testing and derive soil environmental criteria of BaP in terrestrial ecosystems. These findings are effective supplement for the current soil environmental quality standards and will function as the basis for ecological risk assessment of BaP.

Remediation of PAHs contaminated soil enhanced by nano-zero-valent iron combined with white rot fungi Peniophora incarnata

Polycyclic aromatic hydrocarbons (PAHs) are hazardous organic contaminants commonly found in soils. This study investigated an integrated remediation approach combining white rot fungal augmentation and nano-zero-valent iron (nZVI) activated persulfate oxidation to enhance the degradation of PAHs in soil. The white rot fungus Peniophora incarnata demonstrated efficient degradation of lower molecular weight PAHs including phenanthrene (91% removal) and anthracene (71% removal) in liquid culture, but had limited degradation of high molecular weight benzo[a]pyrene (35% removal). Inoculation of P. incarnata in non-sterilized soil led to 54% phenanthrene and 46% anthracene removal after 42 days. Co-inoculation with Pseudomonas aeruginosa slightly improved the degradation by 15% and 13%, respectively. However, benzo[a]pyrene removal was negligible through bioremediation alone. Direct nZVI/persulfate oxidation removed 55–75% of lower molecular weight PAHs and 68% of benzo[a]pyrene in soil. Integrated treatment combining nZVI/persulfate oxidation followed by P. incarnata inoculation resulted in 92–96% degradation of phenanthrene, anthracene and benzo[a]pyrene after 42 days, which was significantly higher than either approach alone. The enhanced PAH removal was attributed to the coupled effects of chemical oxidation and microbial degradation. P. aeruginosa is capable of directly metabolizing and mineralizing lower molecular weight PAHs such as phenanthrene and anthracene. The presence of this additional PAH-degrading bacterium likely contributed to the increased degradation observed. Overall, the sequential nZVI/persulfate and fungal treatment provides an effective and sustainable option for remediating soils co-contaminated with PAHs and other persistent organics. Further research should optimize treatment parameters and evaluate long-term impacts on soil quality.

Enhanced adsorption of benzo(a)pyrene in soil by porous biochar: Adsorption kinetics, thermodynamics, and mechanisms

Soil pollution caused by polycyclic aromatic hydrocarbons (PAHs) poses a significant threat to human health and ecosystems. In this study, a novel porous biochar (PBC) was fabricated from biowastes by one-pot pyrolysis using potassium hydrogen carbonate (KHCO3) as a porogen. The as-prepared PBC was used to remove benzo(a)pyrene (BaP) in contaminated soil for the first time. The PBC obtained at 900 °C had a large surface area (2017.59 m2 g–1), which was approximately 165 times that of the original biochar (BC) (12.16 m2 g–1). The maximum adsorption capacity of BaP by the PBC reached 29.82 mg g–1, which was significantly higher than that of BC (6.94 mg g–1). Adsorption kinetics study indicated the adsorption process fitted a pseudo-second order model, and the adsorption isotherms were consistent with Langmuir model, suggesting BaP adsorption was probably a monolayer molecular adsorption process and that chemisorption was involved. Batch experiments showed that the adsorption efficiency remained high under different initial BaP concentration, initial pH values, temperature, inorganic anion, and humic acid conditions. The results suggested that pore-filling and π-π electron donor-acceptor (EDA) interactions were the main mechanisms for BaP adsorption by PBC, whereas hydrogen bonding and electrostatic interactions only partially contributed to the adsorption process. The soil leaching experiments suggested that the addition of PBC effectively reduced BaP leaching after soil remediation. This study not only provided a cost-effective biochar adsorbent for BaP-contaminated soil remediation, but also shed lights on the mechanisms about adsorption of BaP by PBC in soil.

Experimentally and spectroscopically evidenced mechanistic study of butyl peroxyacid oxidative degradation of benzo[a]pyrene in soil.

Benzo[a]pyrene (BaP) is a major indicator of soil contamination and categorized as a highly persistent, carcinogenic, and mutagenic polycyclic aromatic hydrocarbon. An advanced peroxyacid oxidation process was developed to reduce soil pollution caused by BaP originating from creosote spills from railroad sleepers. The pH, organic matter, particle size distribution of soil, and concentrations of BaP and heavy metals (Cd, Cu, Zn, Pb, and As) in the BaP-contaminated soils were estimated. A batch experiment was conducted to determine the effects of organic acid type, soil particle size, stirring speed, and reaction time on the peroxyacid oxidation of BaP in the soil samples. Additionally, the effect of the organic acid concentration on the peroxyacid degradation of BaP was investigated using an oxidizing agent in spiked soil with and without hydrogen peroxide. The results of the oxidation process indicated that BaP and heavy metal residuals were below acceptable Korean standards. A significant difference in the oxidative degradation of BaP was observed between the spiked and natural soil samples. The formation of a peroxyacid intermediate was primarily responsible for the enhanced BaP oxidation. Further, butyric acid could be reused thrice without losing the efficacy (<90%). The systematic peroxyacid oxidative degradation mechanism of BaP was also discussed. A qualitative analysis of the by-products of the BaP reaction was conducted, and their corresponding toxicities were determined for possible field applications. The findings conclude that the developed peroxyacid oxidation method has potential applications in the treatment of BaP-contaminated soils.

Effect of pyrene-induced changes in root activity on growth of Chinese cabbage (Brassica campestris L.), and the health risks caused by pyrene in Chinese cabbage at different growth stages

BackgroundPolycyclic aromatic hydrocarbons (PAHs) pose a potential risk to ecological safety and human health. They have a range of effects on plant growth and there have been few reports on the health risks associated with ingestion of vegetable crops at different growth stages.MethodologyIn this study, a pot experiment in which Chinese cabbage (Brassica campestris L.) were grown in a greenhouse for 75 days was used to investigate the dose–effect relationship of pyrene with plant growth and also the exposure risk for adults of ingestion of Chinese cabbage at different growth stages.ResultsThe results showed that low doses of pyrene (5–45 mg kg−1) promoted plant growth (20–220% and 55–97% higher than control treatment for the root biomass and shoot biomass, respectively), but significant inhibition was observed at a high dose (405 mg kg−1) (41–66% and 43–91% lower than control treatment for the root biomass and shoot biomass, respectively). High doses of pyrene reduced soil bacterial abundance and diversity during the growth of Chinese cabbage, and increased malondialdehyde (MDA) levels in the plant. The effects of pyrene on plant biomass were mainly attributed to changes in root activity induced by pyrene, as the relationship between soil pyrene concentration and biomass was similar to that between soil pyrene concentration and root activity. Furthermore, structural equation modeling analysis showed that pyrene altered growth of the vegetable by directly affecting root activity. The incremental lifetime cancer risk for adults is highest for ingestion of Chinese cabbage at the seedling stage, followed in decreasing order by the rosette stages and heading stages.ConclusionsThe health risk of consumers who have the possibility to ingest the Chinese cabbage planted in pyrene-contaminated soil would be decreased with the increasing growth periods. However, further studies are required to confirm the dose–effect relationship between pyrene concentration and Chinese cabbage growth on a field scale.Graphical

Enhanced Adsorption of Benzo(A)Pyrene in Soil by Porous Biochar: Adsorption Kinetics, Thermodynamics, and Mechanisms

Enhanced Adsorption of Benzo(A)Pyrene in Soil by Porous Biochar: Adsorption Kinetics, Thermodynamics, and Mechanisms

Effect of Silica on Pyrene-Contaminated Soil Subjected to Mechanochemical Remediation

Soil contaminated by polycyclic aromatic hydrocarbons (PAHs) is a common problem in the world. Mechanochemical treatment is a promising technology for remediation of PAH-contaminated soil. This study investigated the feasibility of pyrene degradation with silica by mechanochemical remediation. The effects of ball milling time and rotation speed on the removal efficiency of pyrene in soil were also studied. When the milling time was 3 h and the rotation speed was 500 rpm, the removal efficiency of pyrene in soil was over 98%. The intermediate products detected by gas chromatography–mass spectrometry proved that the hydrogenation reaction and the destruction of benzene rings occurred in the milling process. Both graphite and amorphous carbon were detected by Raman spectra. The main degradation pathway and mechanism of pyrene by mechanochemical treatment should be the destruction of benzene rings caused by free radicals and further carbonization.

Correction for the effect of soil types on the fluorescence intensity of polycyclic aromatic hydrocarbons

A correction method was proposed and established to reduce the effect of soil types on the PAHs fluorescence intensity based on near-infrared (NIR) diffuse reflectance spectroscopy. The benzo [ghi] pyrene in soil was as the research object. Five types of soil samples with concentration of 1 mg/g benzo [ghi] pyrene were prepared respectively. The fluorescence spectra and NIR diffuse reflectance spectra of all samples were collected. The effects of soil types on the fluorescence spectra and NIR diffuse reflectance spectra were studied. It was found that the effect of soil types on PAHs fluorescence intensities was reduced by dividing the fluorescence intensity by the transformed diffuse reflectance at 4688 cm−1. In order to verify its effectiveness, the established correction method was used to quantitatively analyze the benzo [ghi] pyrene concentration in soil. The correlation coefficients R2 of linear fitting between the fluorescence intensities and concentrations of benzo [ghi] perylene are 0.90 and 0.95 before and after correction, respectively. The average relative prediction error decreased from 35.7% before the correction to 8.71% after the correction. The results show that the established correction method can effectively reduce the effect of soil type on PAHs fluorescence intensity based on NIR diffuse reflectance spectrum. The research can provide theoretical basis and technical support for the accurate and rapid detection of PAHs in soil by fluorescence spectroscopy.

Root exudates enhance the PAH degradation and degrading gene abundance in soils

Root exudates could influence the bioavailability of polycyclic aromatic hydrocarbons (PAHs), provide nutrients for soil microorganisms, and affect PAH biodegradation. However, it remains unclear how a bacterial community and its PAH-degrading genes play crucial roles in PAH biodegradation and respond to root exudates. In this study, a 32-day soil microcosm study was conducted to explore the impacts of artificial and actual root exudates on PAH degradation, degrading genes, and bacterial community structure. The results showed that 10–100 mg DOC/kg artificial and actual root exudates promoted the degradation of naphthalene, phenanthrene, and pyrene in soils, and their percent removal increased initially and then decreased with the increasing root exudates. Quantitative polymerase chain reaction analysis and 16S rRNA gene high-throughput sequencing suggested that the artificial root exudates significantly promoted the Nocardioides and Arthrobacter genera, which may harbor the nidA gene (the representative PAH-degrading gene from Gram-positive bacteria). In contrast, actual root exudates significantly stimulated the Pseudomonas genus that may harbor the nahAc gene (the representative PAH-degrading gene from Gram-negative bacteria). The correlation analysis further indicated that the absolute abundance of PAH degraders and degrading genes had strong correlations with PAH degradation efficiency. Therefore, these findings suggest that root exudates enhanced PAH biodegradation probably due to increases in abundance of both PAH-degraders and their degrading genes.

Root-mediated bacterial accessibility and cometabolism of pyrene in soil

Partial transformation of pollutants and mobilization of the produced metabolites may contribute significantly to the risks resulting from biological treatment of soils polluted by hydrophobic chemicals such as polycyclic aromatic hydrocarbons (PAHs). Pyrene, a four-ringed PAH, was selected here as a model pollutant to study the effects of sunflower plants on the bacterial accessibility and cometabolism of this pollutant when located at a spatially distant source within soil. We compared the transformation of passively dosed 14C-labeled pyrene in soil slurries and planted pots that were inoculated with the bacterium Pseudomonas putida G7. This bacterium combines flagellar cell motility with the ability to cometabolically transform pyrene. Cometabolism of this PAH occurred immediately in the inoculated and shaken soil slurries, where the bacteria had full access to the passive dosing devices (silicone O-rings). Root exudates did not enhance the survival of P. putida G7 cells in soil slurries, but doubled their transport in column tests. In greenhouse-incubated soil pots with the same pyrene sources instead located centimeters from the soil surface, the inoculated bacteria transformed 14C-labeled pyrene only when the pots were planted with sunflowers. Bacterial inoculation caused mobilization of 14C-labeled pyrene metabolites into the leachates of the planted pots at concentrations of approximately 1 mg L−1, ten times greater than the water solubility of the parent compound. This mobilization resulted in a doubled specific root uptake rate of 14C-labeled pyrene equivalents and a significantly decreased root-to-fruit transfer rate. Our results show that the plants facilitated bacterial access to the distant pollutant source, possibly by increasing bacterial dispersal in the soil; this increased bacterial access was associated with cometabolism, which contributed to the risks of biodegradation.

Urea-enhanced phytoremediation of cadmium with willow in pyrene and cadmium contaminated soil

The phytoremediation of cadmium (Cd) and pyrene (PYR) in agricultural soil with willow was investigated by carrying out a pot-culture experiment in a greenhouse. The soil was incubated with urea 60 days before it was used for this experiment. The concentrations of Cd and PYR in soil and willow, the bioconcentration and transfer factors, the physiological and biochemical responses, and plant biomass production were determined at the end of the experiment. The phytoremediation with willow based on urea application was effective for enhancing the phytoremediation of Cd and PYR contaminated soil. Urea application did not affect the available Cd but increased the accumulation of soil Cd and the plant biomass of different parts of the willow. The removal rate (77.1–89.5%) of PYR in soil was not significantly affected although urea application decreased the accumulation of PYR in willow root and bark. Urea application significantly promoted the uptake of chlorophyll, carotenoid and malondialdehyde by willow leaves. The results of this study will provide scientific information for the effective phytoremediation of Cd in Cd and PYR contaminated soil.

Rhizobacterial community of Jatropha curcas associated with pyrene biodegradation by consortium of PAH-degrading bacteria

A bacterial consortium consisting five efficient polyaromatic hydrocarbon (PAH) degraders (Pseudomonas aeruginosa PDB1, Pseudomonas fragi DBC, Klebsiella pneumoniae AWD5, Alcaligenes faecalis BDB4 and Acinetobacter sp. PDB4) was bioaugmented in pyrene contaminated soil through Jatropha curcas rhizosphere, to understand its effect on changes in bacterial community structure during the process of rhizosphere mediated biodegradation of pyrene. This consortium was highly effective in rhizosphere mediated remediation, as 97.2% of pyrene was degraded within 60 days. The better degradation of pyrene in soil was correlated with the changes in bacterial community structure in rhizosphere of J. curcas, for different trials. The Proteobacteria remained the most abundant group among different treatments, but its abundance was 30.7% higher in the rhizosphere of plants growing in pyrene contaminated soil augmented with consortium. Sphingomonas, Sphingobium, Achromobacter, Ralstonia, Pseudoxanthomonas, Devosia, Cupriavidus, and the members of Sphingomonadeceae, Rhizobiaceae, Xanthomonadeceae, were dominant within Proteobacteria, where pyrene degradation was maximum. There was strong correlation between abundances of group of bacteria which were being affected with pyrene contamination or consortium treatment, and this effect was spread over for a group of bacteria, whose abundances were interdependent. Consequently, the treatment of PAH degrading consortium restored and recruited group of bacteria, which were otherwise depleted in presence of pyrene. Therefore, the application of consortium not only facilitated the degradation of pyrene, but also resulted in modulation of the bacterial community in the process of rhizosphere mediated biodegradation of pyrene in soil.

Biotransformation of pyrene in soil in the presence of earthworm Eisenia fetida

Abstract Pyrene, a toxic four benzene ring polycyclic aromatic hydrocarbons (PAHs) that persists in the environment, is highly resistant to degradation. Hence, this study aims to investigate the pyrene degradation by the combination of earthworm (Eisenia fetida) and some microbes in the soil. The artificially contaminated soil (200 g) was prepared in a container box by the addition of pyrene and combined with the addition of the earthworms and some microbes. The results showed that no mortality of earthworms in all soil conditions. The largest amount of pyrene (68.7%) was removed by earthworm microbes in the unsterilized soil. Twelve enzymes were produced such as peroxidase, laccase, invertase, glucosidase, phosphatase, phytase, urease, hydrolase, chitinase, nitrogenase, aminopeptidase, and arylsulfatase. The combination of earthworm and microbes transformed pyrene to protocatechuic acid via pyrene-4,5-dione, phenanthrene-4,5-dicarboxylic acid, and phenanthrene-4-carboxylic acid. But, these compounds were not confirmed in our extract.

The effect of different levels of leachate on phytoremediation of pyrene-contaminated soil and simultaneous extraction of lead and cadmium

Pyrene is one of the 16 group combinations of polyaromatic hydrocarbons, which are known as primary pollutants in the U.S. Environmental Protection Agency (USEPA) list. This study aimed to investigate the cross effect of different levels of landfill leachate on phytoremediation of pyrene-contaminated soil using the sorghum bicolor plant. The study parameters included the presence or absence of the plant, different concentrations of pyrene (150, 300, 500, 750, and 1000 mg kg−1), time (30, 60, and 90 days), and different levels of irrigation with leachate (0, 30, 50, 70, and 100%). Soil pyrene was measured every 30 days, and heavy metals (lead and cadmium) added to the soil by irrigation with leachate were measured in the soil and the plant at the end of 90 days. According to the results, pyrene removal efficiency after 90 days was 96% in irrigation treatments with 30% leachate in the presence of the plant and 67% in irrigation treatments with tap water in the presence of the plant. In addition, 95% of lead and 49% of cadmium added to the soil by irrigation with 30% leachate were extracted from the soil by the sorghum bicolor. According to the results, by increasing nutrients and number of soil bacteria during the cross treatment, landfill leachate increased the pyrene removal efficiency significantly during phytoremediation (p < 0.006) and the sorghum bicolor plant extracted the lead and cadmium of the leachate. In non-planting treatments, although adding high levels of leachate to the soil significantly improved the pyrene removal, it caused the levels of heavy metals, such as lead and cadmium, to exceed the allowable limit (p < 0.001).

Research on the content of pathogenic micromycetes and benz(a)pyrene in soils of urbanized territories of Perm Krai

The content of phytopathogenic fungi and the concentration of benz(a)pyrene in soil samples located near the oil refinery has been investigated. It has been found that in the vast majority of soil samples pathogenic micromicetes are represented by genera Fusarium, Rhizoctonia, Phytophthora, which have a negative effect on crops growth. The highest content of pathogenic micromycetes, amounting to10 CFU per 1 g of soil, was found in soil samples located directly on oil spill territory. It has been found that in an overwhelming number of soil samples, the concentration of benz (a) pyrene, which belongs to organic substances of grade I hazard, exceeds the MPC. The results of the study are consistent with earlier evidence that concentrations of pathogenic micromycetes and benz (a) pyrene are higher in anthropogenic-afected soils. This is due to the negative effect of oil hydrocarbons and benz (a) pyrene on useful soil microflora, and further settlement of the released ecological niche by pathogens. The company is given recommendations on the use of soil for cultivating technical crops or its exclusion from agricultural use.