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The study of microbial hydrocarbons removal is of great importance for the development of future bioremediation strategies. In this study, we evaluated the removal of a gaseous mixture containing toluene, m-xylene, ethylbenzene, cyclohexane, butane, pentane, hexane and heptane in aerated stirred bioreactors inoculated with Rhodococcus erythropolis and operated under non-sterile conditions. For the real-time measurement of hydrocarbons, a novel systematic approach was implemented using Selected-Ion Flow Tube Mass Spectrometry (SIFT-MS). The effect of the carbon source (â¼9.5 ppmv) on (i) the bioreactors' performance (BR1: dosed with only cyclohexane as a single hydrocarbon versus BR2: dosed with a mixture of the 8 hydrocarbons) and (ii) the evolution of microbial communities over time were investigated. The results showed that cyclohexane reached a maximum removal efficiency (RE) of 53% ± 4% in BR1. In BR2, almost complete removal of toluene, m-xylene and ethylbenzene, being the most water-soluble and easy-to-degrade carbon sources, was observed. REs below 32% were obtained for the remaining compounds. By exposing the microbial consortium to only the five most recalcitrant hydrocarbons, REs between 45% ± 5% and 98% ± 1% were reached. In addition, we observed that airborne microorganisms populated the bioreactors and that the type of carbon source influenced the microbial communities developed. The abundance of species belonging to the genus Rhodococcus was below 10% in all bioreactors at the end of the experiments. This work provides fundamental insights to understand the complex behavior of gaseous hydrocarbon mixtures in bioreactors, along with a systematic approach for the development of SIFT-MS methods.
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Biodegradação Ambiental , Reatores Biológicos , Hidrocarbonetos , Rhodococcus , Rhodococcus/metabolismo , Reatores Biológicos/microbiologia , Hidrocarbonetos/metabolismo , Carbono/metabolismo , Poluentes Atmosféricos/metabolismo , Poluentes Atmosféricos/análise , Espectrometria de Massas , Tolueno/metabolismo , Xilenos/metabolismo , Butanos/metabolismo , Derivados de Benzeno , PentanosRESUMO
This study investigated environmental distribution and human exposure of polycyclic aromatic hydrocarbons (PAHs) and their derivatives in one Chinese petroleum refinery facility. It was found that, following with high concentrations of 16 EPA PAHs (∑Parent-PAHs) in smelting subarea of studied petroleum refinery facility, total derivatives of PAHs [named as XPAHs, including nitro PAHs (NPAHs), chlorinated PAHs (Cl-PAHs), and brominated PAHs (Br-PAHs)] in gas (mean= 1.57 × 104 ng/m3), total suspended particulate (TSP) (mean= 4.33 × 103 ng/m3) and soil (mean= 4.37 × 103 ng/g) in this subarea had 1.76-6.19 times higher levels than those from other subareas of this facility, surrounding residential areas and reference areas, indicating that petroleum refining processes would lead apparent derivation of PAHs. Especially, compared with those in residential and reference areas, gas samples in the petrochemical areas had higher ∑NPAH/∑PAHs (mean=2.18), but lower ∑Cl-PAH/∑PAHs (mean=1.43 × 10-1) and ∑Br-PAH/∑PAHs ratios (mean=7.49 × 10-2), indicating the richer nitrification of PAHs than chlorination during petrochemical process. The occupational exposure to PAHs and XPAHs in this petroleum refinery facility were 24-343 times higher than non-occupational exposure, and the ILCR (1.04 × 10-4) for petrochemical workers was considered to be potential high risk. Furthermore, one expanded high-resolution screening through GC Orbitrap/MS was performed for soils from petrochemical area, and another 35 PAHs were found, including alkyl-PAHs, phenyl-PAHs and other species, indicating that profiles and risks of PAHs analogs in petrochemical areas deserve further expanded investigation.
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Monitoramento Ambiental , Petróleo , Hidrocarbonetos Policíclicos Aromáticos , Hidrocarbonetos Policíclicos Aromáticos/análise , China , Petróleo/análise , Humanos , Indústria de Petróleo e Gás , Exposição Ambiental/análise , Poluentes Atmosféricos/análise , Medição de RiscoRESUMO
Polyolefins such as polyethylenes and polypropylenes are the most-produced plastic waste globally, yet are difficult to convert into useful products due to their unreactivity. Pyrolysis is a practical method for large-scale treatment of mixed, contaminated plastic, allowing for their conversion into industrially-relevant petrochemicals. Metal-organic frameworks (MOFs), despite their tremendous utility in heterogenous catalysis, have been overlooked for polyolefin depolymerization due to their perceived thermal instabilities and inability of polyethylenes and polypropylenes to penetrate their pores. Herein, we demonstrate the viability of UiO-66 MOFs containing coordinatively-unsaturated zirconia nodes, as effective catalysts for pyrolysis that significantly enhances the yields of valuable liquid and gas hydrocarbons, whilst halving the amounts of residual solids produced. Reactions occur on the Lewis-acidic UiO-66 zirconia nodes, without the need for noble metals, and yields aliphatic product distributions distinctly different from the aromatic-rich hydrocarbons from zeolite catalysis. We also demonstrate the first unambiguous characterization of polyolefin penetration into UiO-66 pores at pyrolytic temperatures, allowing access to the abundant Zr-oxo nodes within the MOF interior for efficient C-C cleavage. Our work highlights the potential of MOFs as highly-designable heterogeneous catalysts for depolymerization of plastics which can complement conventional catalysts in reactivity.
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Quantitative adverse outcome pathways (qAOPs) describe the response-response relationships that link the magnitude and/or duration of chemical interaction with a specific molecular target to the probability and/or severity of the resulting apical-level toxicity of regulatory relevance. The present study developed the first qAOP for latent toxicities showing that early life exposure adversely affects health at adulthood. Specifically, a qAOP for embryonic activation of the aryl hydrocarbon receptor 2 (AHR2) of fishes by polycyclic aromatic hydrocarbons (PAHs) leading to decreased fecundity of females at adulthood was developed by building on existing qAOPs for (1) activation of the AHR leading to early life mortality in birds and fishes, and (2) inhibition of cytochrome P450 aromatase activity leading to decreased fecundity in fishes. Using zebrafish (Danio rerio) as a model species and benzo[a]pyrene as a model PAH, three linked quantitative relationships were developed: (1) plasma estrogen in adult females as a function of embryonic exposure, (2) plasma vitellogenin in adult females as a function of plasma estrogen, and (3) fecundity of adult females as a function of plasma vitellogenin. A fourth quantitative relationship was developed for early life mortality as a function of sensitivity to activation of the AHR2 in a standardized in vitro AHR transactivation assay to integrate toxic equivalence calculations that would allow prediction of effects of exposure to untested PAHs. The accuracy of the predictions from the resulting qAOP were evaluated using experimental data from zebrafish exposed as embryos to another PAH, benzo[k]fluoranthene. The qAOP developed in the present study demonstrates the potential of the AOP framework in enabling consideration of latent toxicities in quantitative ecological risk assessments and regulatory decision-making. Environ Toxicol Chem 2024;00:1-12. © 2024 SETAC.
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Petroleum hydrocarbons (PHCs) can be biodegraded into CO2, and PHC-contaminated aquifers are always deemed as carbon sources. Fortunately, some carbon fixation microorganisms have been found in PHC-contaminated sites. However, most of the studies are related to volatile short-chain PHC, and few studies focus on long-chain PHC-contaminated sites. To reveal the carbon fixation microorganisms in these sites, in the study, a long-chain PHC polluted site in North China was selected. Through hydrochemical and metagenomics analysis, the structure and capacity of carbon fixing microorganisms in the site were revealed. Results showed that there were many kinds of carbon fixed microorganisms that were identified such as Flavobacterium, Pseudomonas. HP/4HB, rTCA, and DC/4HB cycles were dominated carbon fixation pathways. The long-chain PHC were weakly correlated with carbon fixation microorganisms, but it may stimulate the growth of some carbon fixation microorganisms, such as microorganisms involved in rTCA cycle. PRACTITIONER POINTS: The microorganisms with carbon fixation gene exist in the aquifer contaminated by long-chain petroleum hydrocarbon. Microorganisms that have the ability to degrade petroleum also have the ability to carbon fixation. Long-chain petroleum hydrocarbon may promote the growth of carbon fixation microorganisms.
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Ciclo do Carbono , Água Subterrânea , Hidrocarbonetos , Petróleo , Poluentes Químicos da Água , Petróleo/metabolismo , Hidrocarbonetos/metabolismo , Água Subterrânea/microbiologia , Água Subterrânea/química , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/química , Bactérias/metabolismo , Bactérias/classificação , Bactérias/genética , Biodegradação Ambiental , ChinaRESUMO
Volatile halogenated hydrocarbons (VHHs) are annually produced and released into the environment, posing a threat to public health. In this study, a simple, rapid, sensitive and automated method based on headspace and gas chromatography (GC) with electron-capture detection was described for the determination of VHHs in different concentration levels in water samples. The proposed headspace GC method was initially optimized, and the optimum experimental conditions found were 10-mL water sample containing 20% w/v sodium chloride placed in a 20-mL vial and stirred at 60°C for 35 min, and then 14 VHHs were well separated on DB-35 MS capillary column with a split ratio of 12.5: 1. The limits of detection were in the low µg/L level, ranging between 0.01 and 0.6 µg/L. Finally optimized method was applied for determination 14 VHHs in drinking and environmental waters. The total mean concentrations of VHHs were 34.962, 26.183, 3.228 and 647.344 µg/L in tap water, purified water with 1-year-old filter element, seawater and effluents, respectively. However, no VHHs was detected in purified water with a new filter element. The main composition is different among different water matrix, which may be attributed to their different sources.
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A regular heartbeat is essential for maintaining the homeostasis of the vertebrate body. However, environmental pollutants, oxygen deficiency and extreme temperatures can impair heart function in fish. In this Review, we provide an integrative view of the molecular origins of cardiac arrhythmias and their functional consequences, from the level of ion channels to cardiac electrical activity in living fish. First, we describe the current knowledge of the cardiac excitation-contraction coupling of fish, as the electrical activity of the heart and intracellular Ca2+ regulation act as a platform for cardiac arrhythmias. Then, we compile findings on cardiac arrhythmias in fish. Although fish can experience several types of cardiac arrhythmia under stressful conditions, the most typical arrhythmia in fish - both under heat stress and in the presence of toxic substances - is atrioventricular block, which is the inability of the action potential to progress from the atrium to the ventricle. Early and delayed afterdepolarizations are less common in fish hearts than in the hearts of endotherms, perhaps owing to the excitation-contraction coupling properties of the fish heart. In fish hearts, Ca2+-induced Ca2+ release from the sarcoplasmic reticulum plays a smaller role than Ca2+ influx through the sarcolemma. Environmental changes and ion channel toxins can induce arrhythmias in fish and weaken their tolerance to environmental stresses. Although different from endotherm hearts in many respects, fish hearts can serve as a translational model for studying human cardiac arrhythmias, especially for human neonates.
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Arritmias Cardíacas , Peixes , Animais , Arritmias Cardíacas/fisiopatologia , Arritmias Cardíacas/etiologia , Peixes/fisiologia , Meio Ambiente , Cálcio/metabolismoRESUMO
Polycyclic aromatic hydrocarbons (PAHs) are a class of organic compounds frequently detected in the environment with widely varying toxicities. Many PAHs activate the aryl hydrocarbon receptor (AHR), inducing the expression of a battery of genes, including xenobiotic metabolizing enzymes like Cytochrome P450s (CYPs); however, not all PAHs act via this mechanism. We screened several parent and substituted PAHs in in vitro AHR activation assays to classify their unique activity. Retene (1-methyl-7-isopropylphenanthrene) displays Ahr2 dependent teratogenicity in zebrafish, but did not activate human AHR or zebrafish Ahr2, suggesting a retene metabolite activates Ahr2 in zebrafish to induce developmental toxicity. To investigate the role of metabolism in retene toxicity, studies were performed to determine the functional role of cyp1a, cyp1b1, and the microbiome in retene toxicity, identify the zebrafish window of susceptibility, and measure retene uptake, loss, and metabolite formation in vivo. Cyp1a-null fish were generated using CRISPR-Cas9. Cyp1a-null fish showed increased sensitivity to retene toxicity, while Cyp1b1-null fish were less susceptible, and microbiome elimination had no significant effect. Zebrafish required exposure to retene between 24 and 48 hours post fertilization (hpf) to exhibit toxicity. After static exposure, retene concentrations in zebrafish embryos increased until 24 hpf, peaked between 24 and 36 hpf, and decreased rapidly thereafter. We detected retene metabolites at 36 and 48 hpf, indicating metabolic onset preceding toxicity. This study highlights the value of combining molecular and systems biology approaches with mechanistic and predictive toxicology to interrogate the role of biotransformation in AHR-dependent toxicity.
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A few studies found polycyclic aromatic hydrocarbons (PAHs) were associated with serum uric acid (SUA) or hyperuricemia (HUA). However, the longitudinal study is vacant, and the underlying mechanisms remain unclear. We aimed to assess the cross-sectional and longitudinal associations of urinary PAHs metabolites with SUA levels and HUA risk, and explore the mediating effects of oxidative stress and inflammation. 10 urinary mono-hydroxylated PAHs metabolites and SUA levels were measured among 4047 Chinese urban residents at baseline and 1496 individuals at 6-year follow-up. Biomarkers of oxidative damage and inflammation in urine/plasma were determined at baseline. We adopted generalized linear mixed models and logistic regression to assess the associations of PAHs metabolites with SUA and HUA, weighted quantile sum regression and adaptive elastic net regression to evaluate the overall effects of multi-PAHs mixture, and mediation analysis to estimate the mediating roles of the biomarkers. In the cross-sectional study, each 1-unit increase in the ln-transformed values of 2-OHNa, 2-OHFlu, 4-OHPh, 9-OHPh, 3-OHPh, 2-OHPh, ΣOHNa, ΣOHPh, and ΣOHPAHs was associated with a 4.10-, 3.90-, 6.42-, 7.33-, 4.85-, 5.43-, 4.47-, 7.67-, and 5.22-µmol/L increase in SUA, respectively. Meanwhile, each 1-unit increase in the ln-transformed values of 1-OHNa, 2-OHNa, 4-OHPh, 9-OHPh, 3-OHPh, 2-OHPh, ΣOHNa, ΣOHPh, and ΣOHPAHs was associated with a 17, 14, 15, 22, 14, 19, 18, 27, and 21% increment in HUA risk, respectively. After 6 years, individuals with persistent high level of 9-OHPh had a 12.5 µmol/L increase in SUA compared with those with persistent low level. The overall effects of multi-PAHs mixture on SUA and HUA remain positive. 8-hydroxy-deoxyguanosine mediated the associations of PAHs metabolites with SUA and HUA, and the mediated proportion ranged from 5.39% to 15.34%. PAHs exposure was associated with the elevated SUA levels and increased HUA risk, and oxidative DNA damage may be one of the underlying mechanisms.
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Polycyclic aromatic systems (PASs) are pervasive compounds that have a substantial impact in chemistry and materials science. Although their specific structure-property relationships hold the key to the design of new functional molecules, a detailed understanding of these relationships remains elusive. To elucidate these relationships, we performed a data-driven investigation of the newly generated COMPAS-2 dataset, which contains ~500k molecules consisting of 11 types of aromatic and antiaromatic rings and ranging in size from one to ten rings. Our analysis explores the effects of electron count, geometry, atomic composition, and heterocyclic composition on a range of electronic molecular properties of PASs.
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Eusocial insects, such as ants and termites, are characterized by high levels of coordinated social organization. This is contrasted by solitary insects that display more limited forms of collective behavior. It has been hypothesized that this gradient in sociobehavioral sophistication is positively correlated with chemical profile complexity, due to a potentially increased demand for diversity in chemical communication mechanisms in insects with higher levels of social complexity. However, this claim has rarely been assessed empirically. Here, we compare different levels of chemical and transcriptomic complexity in selected species of the order Blattodea that represent different levels of social organization, from solitary to eusocial. We primarily focus on cuticular hydrocarbon (CHC) complexity, since it has repeatedly been demonstrated that CHCs are key signaling molecules conveying a wide variety of chemical information in solitary as well as eusocial insects. We assessed CHC complexity and divergence between our studied taxa of different social complexity levels as well as the differentiation of their respective repertoires of CHC biosynthesis gene transcripts. Surprisingly, we did not find any consistent pattern of chemical complexity correlating with social complexity, nor did the overall chemical divergence or transcriptomic repertoire of CHC biosynthesis genes reflect on the levels of social organization. Our results challenge the assumption that increasing social complexity is generally reflected in more complex chemical profiles and point toward the need for a more cautious and differentiated view on correlating complexity on a chemical, genetic, and social level.
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Selective photocatalytic CO2 reduction to high-value hydrocarbons using graphitic carbon nitride (g-C3N4) polymer holds great practical significance. Herein, the cyano-functionalized g-C3N4 (CN-g-C3N4) with a high local electron density site is successfully constructed for selective CO2 photoreduction to CH4 and C2H4. Wherein the potent electron-withdrawing cyano group induces a giant internal electric field in CN-g-C3N4, significantly boosting the directional migration of photogenerated electrons and concentrating them nearby. Thereby, a high local electron density site around its cyano group is created. Moreover, this structure can also effectively promote the adsorption and activation of CO2 while firmly anchoring *CO intermediates, facilitating their subsequent hydrogenation and coupling reactions. Consequently, using H2O as a reducing agent, CN-g-C3N4 achieves efficient and selective photocatalytic CO2 reduction to CH4 and C2H4 activity, with maximum rates of 6.64 and 1.35 µmol g-1 h-1, respectively, 69.3 and 53.8 times higher than bulk g-C3N4 and g-C3N4 nanosheets. In short, this work illustrates the importance of constructing a reduction site with high local electron density for efficient and selective CO2 photoreduction to hydrocarbons.
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Necrophagous flies, particularly blowflies, serve as vital indicators in forensic entomology and ecological studies, contributing to minimum postmortem interval estimations and environmental monitoring. The study investigates variations in the predominant cuticular hydrocarbons (CHCs) viz. n-C25, n-C27, n-C28, and n-C29 of empty puparia of Calliphora vicina Robineau-Desvoidy, 1830, (Diptera: Calliphoridae) across diverse environmental conditions, including burial, above-ground and indoor settings, over 90 days. Notable trends include a significant decrease in n-C25 concentrations in buried and above-ground conditions over time, while n-C27 concentrations decline in buried and above-ground conditions but remain stable indoors. Burial conditions show significant declines in n-C27 and n-C29 concentrations over time, indicating environmental influences. Conversely, above-ground conditions exhibit uniform declines in all hydrocarbons. Indoor conditions remain relatively stable, with weak correlations between weathering time and CHC concentrations. Additionally, machine learning techniques, specifically Extreme Gradient Boosting (XGBoost), are employed for age estimation of empty puparia, yielding accurate predictions across different outdoor and indoor conditions. These findings highlight the subtle responses of CHC profiles to environmental stimuli, underscoring the importance of considering environmental factors in forensic entomology and ecological research. The study advances the understanding of insect remnant degradation processes and their forensic implications. Furthermore, integrating machine learning with entomological expertise offers standardized methodologies for age determination, enhancing the reliability of entomological evidence in legal contexts and paving the way for future research and development.
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Hydrocarbon fuels contain approximately 50 times more energy per unit mass than commercial batteries, thus converting even 10% of the energy contained in hydrocarbon fuels to electrical energy could present a more mass-efficient electrical energy source than batteries. Considering the storability of hydrocarbon fuels compared to hydrogen, the viability of direct hydrocarbon polymer electrolyte membrane fuel cells was examined. With extremely pure (> 99.99%) propane, the cell Open-Circuit Voltage (OCV) was only 0.05 V and produced negligible power. However, with addition of trace quantities of unsaturated hydrocarbons, the cell had an OCV of 0.85 V and produced power, even after the unsaturated hydrocarbon addition was discontinued. At sufficiently high current densities, power output gradually decreased then the cell rapidly "extinguished" but by periodically shutting off the current for short time intervals the average power density could be increased significantly. Chemical analysis revealed that no significant amounts of hydrocarbon intermediates or CO were present in the effluent and that conversion of the hydrocarbon fuel to CO2 and H2O was nearly complete. An analytical model incorporating the relative rates of conversion of active anode catalyst sites to inactive sites and vice versa was developed to interpret this behavior. The model predictions were consistent with the experimental observations; possible physical mechanisms are discussed.
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Polycyclic aromatic hydrocarbons (PAHs) are potent inhibitors of DNA that can induce genetic damage, abnormal gene expression, and metabolic disorders upon interfacing with biological macromolecules. However, the mechanism of their interactions with DNA remains elusive. Therefore, this study selected three representative PAHs, including phenanthrene (Phen), pyrene (Pyre), and benzo[a]pyrene (B[a]P), and explored their binding mechanisms with the double-strand DNA (dsDNA) from different species, including 1J1V (Escherichia coli), 6J5B (Arabidopsis thaliana), and 6Q1V (Homo sapiens). The results revealed that binding between PAHs and dsDNA occurred in the groove via van der Waals forces and π-π stacking, with the carboxyl oxygen atom of the thymine (T)-base within dsDNA being the key binding site. This result was further confirmed by the spectroscopic experiments, where significant changes in the peak of the T-base were observed after PAHs-dsDNA binding. More interestingly, the total binding energies of Pyre with the three dsDNA were -138.800 kJ/mol (Pyre-1J1V), -105.523 kJ/mol (Pyre-6J5B), and -127.567 kJ/mol (Pyre-6Q1V), respectively, all of which were higher than those of Phen and B[a]P. This suggests that that Pyre has the strongest dsDNA binding ability. Additionally, analysis of the thermodynamic parameters indicated that the interactions between the three PAHs and dsDNA were exothermic reactions. In contrast, the Pyre-dsDNA interaction predominantly involved van der Waals forces and hydrogen bonding due to the enthalpy change (∆H) < 0 and entropy change (∆S) < 0, while the Phen-dsDNA and B[a]P-dsDNA interactions predominantly involved hydrophobic forces due to ∆H > 0 and ∆S > 0. Furthermore, Pyre caused local distortion of dsDNA, which was more pronounced under atomic force microscopy (AFM). In summary, this study has unveiled a new phenomenon of binding between PAHs and dsDNA. This sheds light on the carcinogenic potential and environmental impacts of PAHs pollution.
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Polycyclic aromatic hydrocarbons (PAHs) are characterized with high KOW values, which lead to their recalcitrant nature, bioaccumulation, and biotoxicity, adversely affects the environment. Passive samplers (PS) have proven effective in measuring bioavailable PAH concentrations for toxicity assessments. In this study, we used low-density polyethylene (LDPE) to measure freely dissolved PAH concentrations (Cfree) in Kentucky Lake (KL) and Ohio River (OH), USA. PAHs toxicity potential in sediment was assessed using equilibrium partitioning sediment benchmarks toxic units (ESBTUs) and the interstitial water toxic units (IWTUs) that were derived from OC-normalized concentration (COC) and Cfree, respectively. The Cfree in April and June were 127 and 97 times higher in OH than in KL, respectively. Moreover, ESBTUs were higher in both the KL and OH compared to the IWTUs, suggesting that ESBTUs overestimate the toxicity potential to organisms. These results indicate that PS provides a reliable method for assessing the toxicity potential in sediments.
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In Ulaanbaatar roughly 60% of the population live in traditional Mongolian yurts in the so-called Ger districts of the city. Winter indoor air quality is a serious concern in these districts as about 98% of households consume solid fossil fuel (mainly coal). In our study, indoor air quality was assessed based on PAHs analysis and ecotoxicity testing of 24-hour samples collected in 4 yurts. Three of the selected yurts were equipped with conventional while the fourth one with improved stoves. Analysis of PAHs profiles showed the prevalence of higher molecular weight PAHs in all yurts. Concentrations of the 5-ring benzo(b)fluoranthene and 6-ring benzo(g.h.i)perylene were extremely high in one yurt using conventional stove, 8430µgg-1 and 6320µgg-1, respectively. Ecotoxicity of the samples was assessed using the kinetic version of the Vibrio fischeri bioluminescence inhibition bioassay. In concordance with PAHs concentrations, ecotoxicity was also the highest in that yurt.
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The present work investigated the effects of different doses of biochar (2.5%, 5%, 10%), a by-product of the pyrolysis of woody biomass, on the growth of oat plants (Avena sativa L., cv "Danko") grown under different crude oil concentrations (0.5%, 1%, 2%, 3%, 6%) added to the soil, evaluating both biometric (i.e. fresh weight) and biochemical (i.e., content of malondialdehyde and proline, and total antioxidant power) parameters. The findings indicate that biochar positively influences the fresh weight of oat plants across all concentrations of crude oil investigated. On the other hand, regarding oxidative stress, measured by malondialdehyde and proline content, biochar led to a significant reduction, with statistical significance observed at biochar concentrations > 2.5% and crude oil levels > 2% (malondialdehyde: ranging from -25% to -38%; proline ranging from -33% to -52%). Soil amendment with biochar increased the total antioxidant power, particularly at biochar concentrations > 2.5% and crude oil levels > 2% (ranging from + 20% to + 98%). These results suggest that biochar has a great potential in mitigating the negative effects of crude oil contamination on plant growth and oxidative stress levels, thereby highlighting its value as a conditioner in contaminated soils.
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Bioethanol is one of the most important bio-resources produced from biomass fermentation and is an environmentally friendly alternative to fossil-based fuels as it is regarded as renewable and clean. Bioethanol and its derivatives are used as feedstocks in petrochemical processes as well as fuel and fuel additives in motor vehicles to compensate for the depletion of fossil fuels. This review chronicles the recent developments in the catalytic conversion of ethanol to diethyl ether, ethylene, propylene, long-chain hydrocarbons, and other important products. Various heterogeneous catalysts, such as zeolites, metal oxides, heteropolyacids, mesoporous materials, and metal-organic frameworks, have been used in the ethanol conversion processes and are discussed extensively. The significance of various reaction parameters such as pressure, temperature, water content in the ethanol feed, and the effect of catalyst modification based on various kinds of literature are critically evaluated. Further, coke formation and coke product analysis using various analytical and spectroscopic techniques during the ethanol conversion are briefly discussed. The review concludes by providing insights into possible research paths pertaining to catalyst design aimed at enhancing the catalytic conversion of (bio)ethanol.
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Although Benzo[a]pyrene (BaP) is considered carcinogenic to humans, the health effects of exposure to ambient levels have not been sufficiently investigated. This study estimated the long-term spatiotemporal variation of BaP in Japan over nearly two decades at a fine spatial resolution of 1 km. This study aimed to obtain an accurate spatiotemporal distribution of BaP that can be used in epidemiological studies on the health effects of ambient BaP exposure. The annual BaP concentrations were estimated using an ensemble machine learning approach using various predictors, including the concentrations and emission intensities of the criteria air pollutants, and meteorological, land use, and traffic-related variables. The model performance, evaluated by location-based cross-validation, exhibited satisfactory accuracy (R2 of 0.693). Densely populated areas showed higher BaP levels and greater temporal reduction, whereas BaP levels remained higher in some industrial areas. The population-weighted BaP in 2018 was 0.12 ng m-3, a decrease of approximately 70% from its 2000 value of 0.44 ng m-3, which was also reflected in the estimated excess number of lung cancer incidences. Accordingly, the proportion of BaP exposure below 0.12 ng m-3, which is the BaP concentration associated with an excess lifetime cancer risk of 10-5, reached 67% in 2018. Our estimates can be used in epidemiological studies to assess the health effects of BaP exposure at ambient concentrations.