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1.
J Environ Qual ; 49(4): 847-857, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33016494

RESUMO

Accurate quantification of petroleum hydrocarbons (PHCs) is required for optimizing remedial efforts at oil spill sites. While evaluating total petroleum hydrocarbons (TPH) in soils is often conducted using costly and time-consuming laboratory methods, visible and near-infrared reflectance spectroscopy (Vis-NIR) has been proven to be a rapid and cost-effective field-based method for soil TPH quantification. This study investigated whether Vis-NIR models calibrated from laboratory-constructed PHC soil samples could be used to accurately estimate TPH concentration of field samples. To evaluate this, a laboratory sample set was constructed by mixing crude oil with uncontaminated soil samples, and two field sample sets (F1 and F2) were collected from three PHC-impacted sites. The Vis-NIR TPH models were calibrated with four different techniques (partial least squares regression, random forest, artificial neural network, and support vector regression), and two model improvement methods (spiking and spiking with extra weight) were compared. Results showed that laboratory-based Vis-NIR models could predict TPH in field sample set F1 with moderate accuracy (R2  > .53) but failed to predict TPH in field sample set F2 (R2  < .13). Both spiking and spiking with extra weight improved the prediction of TPH in both field sample sets (R2 ranged from .63 to .88, respectively); the improvement was most pronounced for F2. This study suggests that Vis-NIR models developed from laboratory-constructed PHC soil samples, spiked by a small number of field sample analyses, can be used to estimate TPH concentrations more efficiently and cost effectively compared with generating site-specific calibrations.


Assuntos
Poluição por Petróleo/análise , Petróleo , Poluentes do Solo/análise , Hidrocarbonetos , Solo
2.
Mar Pollut Bull ; 159: 111483, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32892918

RESUMO

In this study, the formation and fate of oil-related aggregates (ORAs) from chemically dispersed oil in seawater (SW) were investigated at different temperatures (5 °C, 13 °C, 20 °C). Experiments in natural SW alone, and in SW amended with typical marine snow constituents (phytoplankton and mineral particles), showed that the presence of algae stimulated the formation of large ORAs, while high SW temperature resulted in faster aggregate formation. The ORAs formed at 5 °C and 13 °C required mineral particles for sinking, while the aggregates also sank in the absence of mineral particles at 20°. Early in the experimental periods, oil compound accumulation in ORAs was faster than biodegradation, particularly in aggregates with algae, followed by rapid biodegradation. High abundances of bacteria associated with hydrocarbon biodegradation were determined in the ORAs, together with algae-associated bacteria, while clustering analyses showed separation between bacterial communities in experiments with oil alone and oil with algae/mineral particles.


Assuntos
Poluição por Petróleo/análise , Petróleo , Poluentes Químicos da Água/análise , Biodegradação Ambiental , Hidrocarbonetos , Óleos , Água do Mar , Temperatura
3.
Mar Pollut Bull ; 159: 111484, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32892919

RESUMO

In this study a novel sustainable method based on supercritical fluid extraction (SFE) method was developed for simultaneous extraction and fractionation of petroleum biomarkers. We herein proposed a two-step supercritical fluid extraction method for crude oil and tar ball to separate the petroleum biomarkers into aliphatic and aromatic fractions. In the first step, pure scCO2 was used, while scCO2 modified was used as a solvent in the subsequent step. CO2 SFE can serve as an environmental-friendly alternative to common column chromatography method for petroleum biomarker or compositional analysis by GC-MS. The extraction process was shown to be selective, according to the polarity of the solvent, providing fractionation of aliphatic and aromatic hydrocarbons. Yet the total extraction procedure in SFE was significantly faster than column chromatography methods (~80 min vs. 8 h). We will discuss the implications of this SFE method as a novel sustainable alternative to the existing extraction techniques.


Assuntos
Cromatografia com Fluido Supercrítico , Petróleo/análise , Biomarcadores , Fracionamento Químico , Cromatografia Gasosa-Espectrometria de Massas
4.
Sci Total Environ ; 737: 140174, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32783835

RESUMO

Aerobic scope, the difference between standard metabolic requirements and maximum metabolic capacity, is considered a particularly important metric influencing ecological success in fishes. Crude oil exposure can impair cardiorespiratory function in fishes, which reduces maximum metabolic rate, aerobic scope, and may impair ecological performance. Oil exposure is not the only environmental stressor that can affect aerobic scope, especially in areas affected by crude oil spills. Hypoxia (low dissolved oxygen) is also known to constrain maximum metabolic rate, yet there has been little effort to explore how hypoxia may influence the magnitude of metabolic injury following oil exposure. Therefore, our goal was to investigate the effects of acute oil exposure and hypoxia on the metabolic performance of red drum (Sciaenops ocellatus), an economically important fish common in the Gulf of Mexico. Here, sub-adult red drum were exposed to crude oil for 24 h before being exposed to hypoxic conditions following exhaustive exercise. Our results show that hypoxia exposure combined with crude oil exposure results in significantly reduced aerobic scope, which was additive compared to the reductions caused by each stressor alone. We also quantified hypoxia tolerance among treatments following exposure, and our results showed no changes to hypoxia tolerance among individuals, regardless of exposure to hypoxia or oil. These data offer insight into the metabolic constraints facing fishes exposed to oil while concurrently subjected to hypoxia, a notable climate change stressor.


Assuntos
Poluição por Petróleo , Petróleo , Poluentes Químicos da Água , Animais , Golfo do México , Hipóxia
5.
Ecotoxicol Environ Saf ; 202: 110959, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800231

RESUMO

Long-term field experiments were performed to evaluate the phytotoxic properties of fungal metabolites in oil-contaminated soil and to assess the impact of contamination on the allelopathic activity of soil mycobiota. Two contrasting soils of Northwest Russia (sandy and loamy podzols) exposed to oil contamination underwent changes in abundance and allelopathic activities of soil fungi. Shifts within the microbial community caused by oil contamination affected not only oil-decomposition rates but also ecotoxicity of contaminated soil. There were significant differences in soil toxicity dynamics between sandy and loamy podzols. Four years after contamination, ecotoxicity of loamy podzol decreased, whereas sandy podzol remained highly toxic even nine years after contamination. The abundance and allelopathic activity of fungi is correlated with hydrocarbon degradation dynamics. The soil fungal community demonstrated high allelopathic activity which decreased over time in fertile loamy podzolic soil, whereas in poor sandy podzolic soil it remained high over the nine-year monitoring period. The results illustrate how oil contamination may influence allelopathic interactions in soil and demonstrate the advantage of using fungal metabolite toxicity test for testing of oil-contaminated soil samples.


Assuntos
Fungos/efeitos dos fármacos , Hidrocarbonetos/toxicidade , Micotoxinas/toxicidade , Petróleo/toxicidade , Microbiologia do Solo , Poluentes do Solo/análise , Animais , Biodegradação Ambiental , Daphnia/efeitos dos fármacos , Daphnia/crescimento & desenvolvimento , Ecotoxicologia , Fungos/metabolismo , Hidrocarbonetos/análise , Micotoxinas/metabolismo , Petróleo/análise , Federação Russa , Solo/química , Testes de Toxicidade , Triticum/efeitos dos fármacos , Triticum/crescimento & desenvolvimento
6.
J Environ Manage ; 271: 110941, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32778265

RESUMO

A real crude oil-contaminated soil was treated using a two-step method: biosurfactant-assisted soil washing and the biostimulated biotreating of the effluent. The mixture of surfactin and rhamnolipid could enhance the TPH removal from an oil-contaminated soil (32 g/kg) in the soil washing operation. 86% of TPH was removed from the oil-contaminated soil in the soil washing operation under the mixed biosurfactant (surfactin + rhamnolipid) of 0.6 g/L, the soil/water ratio of 20 w/v%, the temperature of 30 °C, and the washing time of 24 h, leaving an effluent containing 5028 mg/L TPH. The effluent was efficiently biotreated in the bioprocess with 5 g/L acclimate biomass daily stimulated with 0.1 mM H2O2, and the concentrtion of TPH decreased to 26 mg/L within 17 d corresponding a TPH biodegradation over 99%. The biostimulation with H2O2 caused the production of a high amount of peroxidase that could accelerate the biodegradation of TPH. Accordingly, the findings suggest that the biosurfactant-assisted washing operation combined with the H2O2-stimulated biodegradation process could be an enhanced green method for efficient treatment of the heavy oil-contaminated soils.


Assuntos
Petróleo , Poluentes do Solo/análise , Biodegradação Ambiental , Peróxido de Hidrogênio , Solo , Microbiologia do Solo , Tensoativos
7.
J Environ Manage ; 271: 110997, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32778285

RESUMO

Gas ebullition in sediment results from biogenic gas production by mixtures of bacteria and archaea. It often occurs in organic-rich sediments that have been impacted by petroleum hydrocarbon (PHC) and other anthropogenic pollution. Ebullition occurs under a relatively narrow set of biological, chemical, and sediment geomechanical conditions. This process occurs in three phases: I) biogenic production of primarily methane and dissolved phase transport of the gases in the pore water to a bubble nucleation site, II) bubble growth and sediment fracture, and III) bubble rise to the surface. The rate of biogenic gas production in phase I and the resistance of the sediment to gas fracture in phase II play the most significant roles in ebullition kinetics. What is less understood is the role that substrate structure plays in the rate of methanogenesis that drives gas ebullition. It is well established that methanogens have a very restricted set of compounds that can serve as substrates, so any complex organic molecule must first be broken down to fermentable compounds. Given that most ebullition-active sediments are completely anaerobic, the well-known difficulty in degrading PHCs under anaerobic conditions suggests potential limitations on PHC-derived gas ebullition. To date, there are no studies that conclusively demonstrate that weathered PHCs can alone drive gas ebullition. This review consists of an overview of the factors affecting gas ebullition and the biochemistry of anaerobic PHC biodegradation and methanogenesis in sediment systems. We next compile results from the scholarly literature on PHCs serving as a source of methanogenesis. We combine these results to assess the potential for PHC-driven gas ebullition using energetics, kinetics, and sediment geomechanics analyses. The results suggest that short chain 

Assuntos
Petróleo , Gases/análise , Sedimentos Geológicos , Hidrocarbonetos , Metano
8.
Environ Monit Assess ; 192(9): 569, 2020 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-32770276

RESUMO

Hydrocarbon contamination due to anthropogenic activities is a major environmental concern worldwide. The present study focuses on biochar prepared from fruit and vegetable waste and sewage sludge using a thermochemical approach and its application for the enhanced bioremediation (biostimulation and bioaugmentation) of diesel-polluted soil. The biochar was characterized using FTIR (Fourier-transform infrared spectroscopy), elemental analysis, surface area analysis, and pore analysis. Adsorption experiments showed that hydrocarbon degradation was attributed to biological processes rather than adsorption. The study found that various biochar amendments could significantly increase the rate of hydrocarbon biodegradation with removal efficiencies > 70%. Bioaugmentation using cow dung further improved the removal efficiency to 82%. Treatments showing the highest degree of removal efficiency indicated the presence of 27 different bacteria phyla with Proteobacteria and Actinobacteria as the most abundant phyla. The present study concludes that biochar amendments have great potential for enhancing the bioremediation of soils contaminated with diesel range hydrocarbons.


Assuntos
Petróleo , Poluentes do Solo/análise , Animais , Biodegradação Ambiental , Bovinos , Carvão Vegetal , Monitoramento Ambiental , Feminino , Hidrocarbonetos , Solo , Microbiologia do Solo
9.
J Environ Manage ; 272: 111057, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32854876

RESUMO

Petroleum refinery and petrochemical plants (PRPP) are one of the major contributors to toxic and recalcitrant organic polluted water, which has become a significant concern in the field of environmental engineering. Several contaminants of PRPP wastewater are genotoxic, phytotoxic, and carcinogenic, thereby imposing detrimental effects on the environment. Many biological processes were able to achieve chemical oxygen demand (COD) removal ranging from 60% to 90%, and their retention time usually ranged from 10 to 100 days. These methods were not efficient in removing the petroleum hydrocarbons present in PRPP wastewater and produced a significant amount of oily sludge. Advanced oxidation processes achieved the same COD removal efficiency in a few hours and were able to break down recalcitrant organic compounds. However, the associated high cost is a significant drawback concerning PRPP wastewater treatment. In this context, constructed wetlands (CWs) could effectively remove the recalcitrant organic fraction of the wastewater because of the various inherent mechanisms involved, such as phytodegradation, rhizofiltration, microbial degradation, sorption, etc. In this review, we found that CWs were efficient in handling large quantities of high strength PRPP wastewater exhibiting average COD removal of around 80%. Horizontal subsurface flow CWs exhibited better performance than the free surface and floating CWs. These systems could also effectively remove heavy oil and recalcitrant organic compounds, with an average removal efficiency exceeding 80% and 90%, respectively. Furthermore, modifications by varying the aeration system, purposeful hybridization, and identifying the suitable substrate led to the enhanced performance of the systems.


Assuntos
Petróleo , Purificação da Água , Biodegradação Ambiental , Eliminação de Resíduos Líquidos , Águas Residuárias/análise , Áreas Alagadas
10.
Water Sci Technol ; 81(12): 2501-2510, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32857738

RESUMO

The exploitation of petroleum in offshore areas is becoming more prosperous due to the increasing human demand for oil. However, the effects of offshore petroleum exploitation on the microbial community in the surrounding environment are still not adequately understood. In the present study, variations in the composition, function, and antibiotic resistance of the microbial community in marine sediments adjacent to an offshore petroleum exploitation platform were analyzed by a metagenomics-based method. Significant shifts in the microbial community composition were observed in sediments impacted by offshore petroleum exploitation. Nitrosopumilales was enriched in marine sediments with the activities of offshore petroleum exploitation compared to the control sediments. The abundances of function genes involved in carbon, butanoate, methane, and fatty acid metabolism in sediment microbial communities also increased due to the offshore petroleum exploitation. Offshore petroleum exploitation resulted in the propagation of some antibiotic resistance genes (ARGs), including a multidrug transporter, smeE, and arnA, in marine sediments via horizontal gene transfer mediated by class I integrons. However, the total abundance and diversity of ARGs in marine sediments were not significantly affected by offshore petroleum exploitation. This study is the first attempt to analyze the impact of offshore petroleum exploitation on the spread of antibiotic resistance.


Assuntos
Microbiota , Petróleo , Antibacterianos , Bactérias/genética , Genes Bacterianos , Sedimentos Geológicos , Humanos
11.
Environ Pollut ; 266(Pt 3): 115202, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32823065

RESUMO

Bioremediation has gained global prominence as an effective method for treating hydrocarbon-contaminated drill mud waste (HCDW). However, the problem of low nutrient content, bioavailability and microbial presence remain largely unresolved. In this study, the synergistic effects of compost, cow bile and bacterial culture on the degradation rate of HCDW was investigated. A homogenized HCDW sample (80 kg) obtained from 25 different drill mud tanks was divided into 20 portions (4 kg each) and each adjusted to 1.4% nitrogen content + 20 ml cow bile (i.e., basic treatment). Pure cultures of Brevibacterium casei (Bc) and Bacillus zhangzhouensi (Bz) and their mixture (BcBz) were subsequently added to 12 of the amended HCDW (basic) to undergo a 6-week incubation. A portion of the unamended HCDW (2 kg) was used as control. Initial pH, electrical conductivity and surface tension values of the HCDW were 8.83, 2.34 mS/cm and 36.5 mN/m, respectively. Corresponding values for total petroleum hydrocarbon (TPH), total nitrogen and total plate count bacteria were 165 g/kg, 0.04% and 4.4 × 102 cfu/ml. The treatments led to a substantial reduction in TPH (p < 0.05) while the control had no significant effect (p > 0.05). TPH reduction after the experimental period occurred in the order: basic + BcBz (99.7%) > basic + Bz (99.5%) > basic + Bc (99.2%) > basic (95.2%) > control (0.06%). Multiple regression analysis revealed significant effect of total plate count, pH, CN ratio and electrical conductivity (R2 = 0.87, p = 0.05) on the degradation of TPH in the HCDW. The study demonstrates strong interactive effects of compost, cow bile and bacteria culture on the remediation of HCDW, which can be applied to boost the efficiency of the bioremediation technique.


Assuntos
Compostagem , Petróleo , Poluentes do Solo/análise , Animais , Bile , Biodegradação Ambiental , Brevibacterium , Bovinos , Feminino , Hidrocarbonetos , Solo , Microbiologia do Solo
12.
Mar Pollut Bull ; 159: 111485, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32763559

RESUMO

Increased knowledge about the fate and behaviour of weathered oil in different sea ice conditions is essential for our ability to model oil spill trajectories in ice more precisely and for oil spill response decision making in northern and Arctic areas. As part of the 3-year project: "Fate, Behaviour and Response to Oil Drifting into Scattered Ice and Ice Edge in the Marginal Ice Zone", a novel wave and current flume was built to simulate these processes in the laboratory. This paper discusses some of the findings from this project, which included Marine Gas Oil and four Norwegian crude oils. All crude oils were weathered prior to testing, simulating having drifted on the sea surface for a period (tentatively 1-3 days) before encountering ice. The build-up of oil drifting against an ice barrier and horizontal and vertical migration of oil droplets under solid ice and in frazil ice was studied.


Assuntos
Poluição por Petróleo/análise , Petróleo , Regiões Árticas , Camada de Gelo , Noruega
13.
Mar Pollut Bull ; 159: 111462, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32777544

RESUMO

In this study, the concentrations of 28 polychlorinated biphenyl (PCB) congeners, including 12 dioxin-like PCBs and 7 indicator PCBs, were determined in sediments around oil production facilities in the Escravos River Basin of the Niger Delta in Nigeria. The aim was to describe the spatial patterns, sources, and ecosystem risks associated with exposure to PCBs in sediments of this river basin. Gas chromatography-mass spectrometry (GC-MS) was used to determine the concentrations of PCBs in the sediments. The Æ©28 PCB concentrations in sediments from the Escravos River Basin ranged between 226 and 31,900 ng g-1 with a median concentration of 2300 ng g-1. The results indicated that sediments around crude oil production facilities, such as, wellheads, flow stations, and truck lines, had significantly higher levels of Æ©28 PCBs (p < 0.05) than those collected near residential communities within the river basin. The median concentrations of PCB homologues in sediments from this river basin followed the sequence: hexaPCBs > penta-PCBs > tetra-PCBs > hepta-PCBs > tri-PCBs > di-PCBs > deca-PCBs > octa-PCBs > nona-PCBs. The risk assessment of PCBs in sediments from this river basin suggest very high potential risks for both organisms and humans.


Assuntos
Petróleo , Bifenilos Policlorados/análise , Poluentes Químicos da Água/análise , Ecossistema , Monitoramento Ambiental , Sedimentos Geológicos , Humanos , Níger , Nigéria , Medição de Risco , Rios
14.
Sci Total Environ ; 745: 140639, 2020 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-32758758

RESUMO

The Deepwater Horizon (DWH) oil spill marked the largest environmental oil spill in human history, where it was estimated a large amount of the polycyclic aromatic hydrocarbons (PAHs) were released with crude oil into the environment. In this study, common PAH compounds were quantitatively determined in crude oil from the DWH spill by gas chromatography-mass spectroscopy (GC-MS). Twelve PAH compounds were identified and quantified from a 100× dilution of DWH crude oil: naphthalene (7800 ng/mL), acenaphthylene (590 ng/mL), acenaphtehen (540 ng/mL), fluorene (2550 ng/mL), phenanthrene (2910 ng/mL), anthracene (840 ng/mL), fluoranthene (490 ng/mL), pyrene (290 ng/mL), benzo(k) fluoranthene (1050 ng/mL), benzo(b)fluoranthene (1360 ng/mL), dibenz(a,h)anthracene (2560 ng/mL), and benzo(g, h, i) perylene (630 ng/mL). Toxicity assays using the nematode, Caenorhabditis elegans (C. elegans), indicated a single PAH compound naphthalene, exposure increased C. elegans germ cell apoptosis which may adversely affect progeny reproduction. The number of apoptotic germ cells significantly increased from 1.4 to 2.5 when worms were treated with 10 µg/mL of naphthalene and from 1.3 to 2.5 and 3.5 cells in presence of 1 µg/mL and 5 µg/mL of benzo(a)pyrene, respectively. Five CYP450 genes (CYP14A3, CYP35A1, CYP35A2, CYP35A5, and CYP35C1) were significantly upregulated following 500× dilution of dispersed crude oil exposure (p < 0.05). These results suggest that CYP450s may play a role in bioactivation of PAHs in crude oil, resulting in DNA damage related germ cell apoptosis.


Assuntos
Petróleo/toxicidade , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Animais , Apoptose , Caenorhabditis elegans , Sistema Enzimático do Citocromo P-450/efeitos dos fármacos , Sistema Enzimático do Citocromo P-450/metabolismo , Células Germinativas , Humanos , Regulação para Cima
15.
Aquat Toxicol ; 227: 105582, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32823071

RESUMO

While it is likely that ENPs may occur together with other contaminants in nature, the combined effects of exposure to both ENPs and environmental contaminants are not studied sufficiently. In this study, we investigated the acute and sublethal toxicity of PVP coated silver nanoparticles (AgNP) and ionic silver (Ag+; administered as AgNO3) to the marine copepod Calanus finmarchicus. We further studied effects of single exposures to AgNPs (nominal concentrations: low 15 µg L-1 NPL, high 150 µg L-1 NPH) or Ag+ (60 µg L-1), and effects of co-exposure to AgNPs, Ag+ and the water-soluble fraction (WSF; 100 µg L-1) of a crude oil (AgNP + WSF; Ag++WSF). The gene expression and the activity of antioxidant defense enzymes SOD, CAT and GST, as well as the gene expression of HSP90 and CYP330A1 were determined as sublethal endpoints. Results show that Ag+ was more acutely toxic compared to AgNPs, with 96 h LC50 concentrations of 403 µg L-1 for AgNPs, and 147 µg L-1 for Ag+. Organismal uptake of Ag following exposure was similar for AgNP and Ag+, and was not significantly different when co-exposed to WSF. Exposure to AgNPs alone caused increases in gene expressions of GST and SOD, whereas WSF exposure caused an induction in SOD. Responses in enzyme activities were generally low, with significant effects observed only on SOD activity in NPL and WSF exposures and on GST activity in NPL and NPH exposures. Combined AgNP and WSF exposures caused slightly altered responses in expression of SOD, GST and CYP330A1 genes compared to the single exposures of either AgNPs or WSF. However, there was no clear pattern of cumulative effects caused by co-exposures of AgNPs and WSF. The present study indicates that the exposure to AgNPs, Ag+, and to a lesser degree WSF cause an oxidative stress response in C. finmarchicus, which was slightly, but mostly not significantly altered in combined exposures. This indicated that the combined effects between Ag and WSF are relatively limited, at least with regard to oxidative stress.


Assuntos
Copépodes/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Petróleo/toxicidade , Prata/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Antioxidantes/metabolismo , Copépodes/genética , Copépodes/metabolismo , Interações Medicamentosas , Expressão Gênica/efeitos dos fármacos , Íons , Nanopartículas Metálicas/química , Estresse Oxidativo/genética , Água do Mar/química , Prata/química , Solubilidade , Testes de Toxicidade Aguda , Testes de Toxicidade Subaguda , Poluentes Químicos da Água/química
16.
PLoS One ; 15(8): e0237172, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32817623

RESUMO

This paper contributes to better understand the dynamic interactions between effective exchange rate (EER) and oil price for an oil-importing country like the U.S. by considering a Time-Varying Parameter VAR model with the use of monthly data from 1974:01 to 2019:07. Our findings show a depreciation after an oil price shock in the short-run for any period of time, although the pattern of long-run responses of U.S. EER is diverse across time periods, with an appreciation being observed before the mid-2000s and after the mid-2010s, and a depreciation between both periods. This diversity of response should lead policy makers to react differently in order to counteract such shocks. Furthermore, the reaction of oil price to an appreciation of U.S. EER is negative and different over time, which may generate different adverse effects on investment. The knowledge of such effects may help financial investors to diversify their investments in order to optimize the risk-return profile of their portfolios.


Assuntos
Comércio , Modelos Econômicos , Petróleo/economia , Teorema de Bayes , Humanos , Investimentos em Saúde/economia , Cadeias de Markov , Distribuição Normal , Estados Unidos
17.
Ecotoxicol Environ Saf ; 204: 111083, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32791359

RESUMO

Due to the accumulation of heavy metals in soil ecosystems, the response of soil microorganisms to the disturbance of heavy metals were widely studied. However, little was known about the interactions among microorganisms in heavy metals and total petroleum hydrocarbons (TPH) co-contaminated soils. In the present study, the microbiota shifts of 2 different contamination types of heavy metal-TPH polluted soils were investigated. NGS sequencing approach was adopted to illustrate the microbial community structure and to predict community function. Networks were established to reveal the interactions between microbes and environmental pollutants. Results showed that the alpha diversity and OTUs number of soil microbiota were reduced under heavy metals and TPH pollutants. TPH was the major pollutant in HT1 group, in which Proteobacteria phylum increased significantly, including Arenimonas genus, Sphingomonadaceae family and Burkholderiaceae family. Moreover, the function structures based on the KEGG database of HT1 group was enriched in the benzene matter metabolism and bacterial motoricity in microbiota. In contrast, severe Cr-Pb-TPH co-pollutants in HT2 increased the abundance of Firmicutes. In details, the relative abundance of Streptococcus genus and Bacilli class raised sharply. The DNA replication functions in microbiota were enriched under severely contaminated soil as a result of high concentrations of heavy metals and TPH pollutants' damage to bacteria. Furthermore, according to the correlation analysis between microbes and the pollutants, Streptococcus, Neisseria, Aeromonas, Porphyromonas and Acinetobacter were suggested as the bioremediation bacteria for Cr and Pb polluted soils, while Syntrophaceae spp. and Immundisolibacter were suggested as the bioremediation bacteria for TPH polluted soil. The study took a survey on the microbiota shifts of the heavy metals and TPH polluted soils, and the microbe's biomarkers provided new insights for the candidate strains of biodegradation, while further researches are required to verify the biodegradation mechanism of these biomarkers.


Assuntos
Hidrocarbonetos/toxicidade , Metais Pesados/toxicidade , Microbiota/efeitos dos fármacos , Petróleo/toxicidade , Microbiologia do Solo , Poluentes do Solo/toxicidade , Solo/química , Biodegradação Ambiental , Firmicutes/efeitos dos fármacos , Firmicutes/metabolismo , Hidrocarbonetos/análise , Metais Pesados/análise , Petróleo/análise , Poluição por Petróleo/análise , Proteobactérias/efeitos dos fármacos , Proteobactérias/metabolismo , Poluentes do Solo/análise
18.
Bioresour Technol ; 315: 123861, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32702582

RESUMO

Primarily, this study aims to evaluate the biosurfactant production capability of Stenotrophomonas sp. S1VKR-26, profiling of its bioremediation ability to remediate petroleum refinery wastewater in a lab-scale bioreactor and assessment of phytotoxicity of bioremediated petroleum wastewater. As a result, strain S1VKR-26 was found to produce 5.15 g L-1 biosurfactant, CMC of 30 mg L-1 and reduced the surface tension from 60.3 to 30.5 mN m-1. Different PAHs like naphthalene (93%), phenanthrene (86%), fluoranthene (92%), and pyrene (98.3%), total petroleum hydrocarbons (72.33%) and phenolic compounds (93.06%) were significantly remediated from the wastewater after the treatment of strain S1VKR-26. Moreover, S1VKR-26 strain treated 1:1 diluted petroleum wastewater have higher germination (100%), vigor (486), and seedling (4.86 cm) compared to untreated wastewater. Therefore, the treatment of petroleum refinery wastewater with strain S1VKR-26 could be more effective in the sense of environmental safety and irrigation for crop production in agriculture.


Assuntos
Petróleo , Biodegradação Ambiental , Hidrocarbonetos , Stenotrophomonas , Tensoativos , Águas Residuárias
19.
Bull Environ Contam Toxicol ; 105(2): 230-236, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32671410

RESUMO

Fifty-four surface sediments from the typical coal mining area were analyzed for pristane, phytane and C8-C40 n-alkanes using gas chromatography-mass spectrometry (GC-MS). The spatial distribution, homolog profiles and source apportionment of aliphatic hydrocarbons were investigated. Bimodal distribution pattern, centered at C16-C20 and C27-C33 n-alkanes, were observed in all sediment samples with an obvious dominance of low molecular weight homologues. Principal component analysis-multiple linear regression (PCA-MLR) was used to predict the contributions of different sources. The result implied that natural input was the main source, contribution of which accounted for 60.8%, and the contributions of different sources were estimated as follow: 21.8% for terrestrial higher plants, 24.1% for algae and photosynthetic bacteria, 14.9% for submerged/floating macrophytes, 23.5% for fossil fuel combustion and 15.7% for petroleum hydrocarbons. Moreover, relatively high median concentrations of fossil fuel combustion were observed in Shou County and Fengtai County, indicating the high contribution of fossil fuel combustion in these two areas.


Assuntos
Minas de Carvão , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Hidrocarbonetos/análise , Petróleo/análise , Alcanos/análise , China , Diterpenos/análise , Cromatografia Gasosa-Espectrometria de Massas , Hidrocarbonetos Policíclicos Aromáticos/análise , Análise de Componente Principal , Terpenos/análise , Poluentes Químicos da Água/análise
20.
PLoS One ; 15(7): e0235473, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32634146

RESUMO

Diatoms play a key role in the marine carbon cycle with their high primary productivity and release of exudates such as extracellular polymeric substances (EPS) and transparent exopolymeric particles (TEP). These exudates contribute to aggregates (marine snow) that rapidly transport organic material to the seafloor, potentially capturing contaminants like petroleum components. Ocean acidification (OA) impacts marine organisms, especially those that utilize inorganic carbon for photosynthesis and EPS production. Here we investigated the response of the diatom Thalassiosira pseudonana grown to present day and future ocean conditions in the presence of a water accommodated fraction (WAF and OAWAF) of oil and a diluted chemically enhanced WAF (DCEWAF and OADCEWAF). T. pseudonana responded to WAF/DCEWAF but not OA and no multiplicative effect of the two factors (i.e., OA and oil/dispersant) was observed. T. pseudonana released more colloidal EPS (< 0.7 µm to > 3 kDa) in the presence of WAF/DCEWAF/OAWAF/OADCEWAF than in the corresponding Controls. Colloidal EPS and particulate EPS in the oil/dispersant treatments have higher protein-to-carbohydrate ratios than those in the control treatments, and thus are likely stickier and have a greater potential to form aggregates of marine oil snow. More TEP was produced in response to WAF than in Controls; OA did not influence its production. Polyaromatic hydrocarbon (PAH) concentrations and distributions were significantly impacted by the presence of dispersants but not OA. PAHs especially Phenanthrenes, Anthracenes, Chrysenes, Fluorenes, Fluoranthenes, Pyrenes, Dibenzothiophenes and 1-Methylphenanthrene show major variations in the aggregate and surrounding seawater fraction of oil and oil plus dispersant treatments. Studies like this add to the current knowledge of the combined effects of aggregation, marine snow formation, and the potential impacts of oil spills under ocean acidification scenarios.


Assuntos
Diatomáceas/efeitos dos fármacos , Poluição por Petróleo/efeitos adversos , Petróleo/toxicidade , Tensoativos/efeitos adversos , Organismos Aquáticos/efeitos dos fármacos , Humanos , Hidrocarbonetos Policíclicos Aromáticos/efeitos adversos , Hidrocarbonetos Policíclicos Aromáticos/química , Água do Mar/química , Tensoativos/química , Poluentes Químicos da Água/efeitos adversos , Poluentes Químicos da Água/química
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