Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.732
Filtrar
1.
Environ Monit Assess ; 192(6): 342, 2020 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-32382809

RESUMO

Benzene, toluene, ethylbenzene and xylenes (BTEX) are well known hazardous volatile organic compounds (VOCs) due to their human health risks and photochemical effects. The main objective of this study was to estimate BTEX levels and evaluate interspecies ratios and ozone formation potentials (OFP) in the ambient air of urban Kuala Lumpur (KL) based on a passive sampling method with a Tenax® GR adsorbent tube. Analysis of BTEX was performed using a thermal desorption (TD)-gas chromatography mass spectrometer (GCMS). OFP was calculated based on the Maximum Incremental Reactivity (MIR). Results from this study showed that the average total BTEX during the sampling period was 66.06 ± 2.39 µg/m3. Toluene (27.70 ± 0.97 µg/m3) was the highest, followed by m,p-xylene (13.87 ± 0.36 µg/m3), o-xylene (11.49 ± 0.39 µg/m3), ethylbenzene (8.46 ± 0.34 µg/m3) and benzene (3.86 ± 0.31 µg/m3). The ratio of toluene to benzene (T:B) is > 7, suggesting that VOCs in the Kuala Lumpur urban environment are influenced by vehicle emissions and other anthropogenic sources. The average of ozone formation potential (OFP) value from BTEX was 278.42 ± 74.64 µg/m3 with toluene and xylenes being the major contributors to OFP. This study also indicated that the average of benzene concentration in KL was slightly lower than the European Union (EU)-recommended health limit value for benzene of 5 µg/m3 annual exposure.


Assuntos
Poluentes Atmosféricos , Monitoramento Ambiental , Benzeno , Derivados de Benzeno , Humanos , Tolueno , Xilenos
2.
Chemosphere ; 255: 126932, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32402880

RESUMO

The aim of the present study was to investigate the potential sources of heavy metals in fine air particles (PM2.5) and benzene, toluene, ethylbenzene, and isomeric xylenes (BTEX) in gas phase indoor air. PM2.5 samples were collected using a low volume sampler. BTEX samples were collected using passive sampling onto sorbent tubes and analyzed using gas chromatography-mass spectrometry (GC-MS). For the lower and upper floors of the evaluated building, the concentrations of PM2.5 were 96.4 ± 2.70 µg/m3 and 80.2 ± 3.11 µg/m3, respectively. The compositions of heavy metals in PM2.5 were predominated by iron (Fe), zinc (Zn), and aluminum (Al) with concentration of 500 ± 50.07 ng/m3, 466 ± 77.38 ng/m3, and 422 ± 147.38 ng/m3. A principal component analysis (PCA) showed that the main sources of BTEX were originated from vehicle emissions and exacerbate because of temperature variations. Hazard quotient results for BTEX showed that the compounds were below acceptable limits and thus did not possess potential carcinogenic risks. However, a measured output of lifetime cancer probability revealed that benzene and ethylbenzene posed definite carcinogenic risks. Pollutants that originated from heavy traffic next to the sampling site contributed to the indoor pollution.


Assuntos
Monitoramento Ambiental/métodos , Material Particulado/análise , Compostos Orgânicos Voláteis/análise , Poluentes Atmosféricos/análise , Benzeno/análise , Derivados de Benzeno , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Tolueno/análise , Emissões de Veículos/análise , Xilenos/análise
3.
Chemosphere ; 252: 126571, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32224361

RESUMO

An exoelectrogens, Shewanella oneidensis MR-1 (S. oneidensis MR-1), was supplied to a microbial fuel cell (MFC) to enhance the degradation of a recalcitrant organic compound, o-xylene. The experimental results revealed that, with the addition of the S. oneidensis MR-1, the o-xylene removal efficiency increased by 35-76% compared with the original MFC. The presence of the S. oneidensis MR-1 not only improved the activity of the biofilm in the bioanode but also developed the connections between the bacteria by nanowires. Therefore, the maximum power density increased from 52.1 to 92.5 mW/m3 after the addition of the S. oneidensis MR-1. The microbial community analysis showed that adding the S. oneidensis MR-1 increased the biodiversity in bioanode. The dominant exoelectrogens shifted from Zoogloea sp., Delftia sp., Achromobacter sp., Acinetobacter sp., Chryseobacterium sp., and Stenotrophomonas sp. to Zoogloea sp., Delftia sp., Shewanella sp., Achromobacter sp., Hydrogenophaga sp., Sedimentibacter sp. and Chryseobacterium sp.. Furthermore, the cyclic voltammetry analysis showed that the outer membrane bound protein complex of OmcA-MtrCAB was involved as direct electron transfer pathway in the S. oneidensis MR-1 containing bioanode. We believed that this work is promising to provide optional strategy for efficient VOCs degradation by adjusting the microbial community in the bioanode.


Assuntos
Fontes de Energia Bioelétrica/microbiologia , Shewanella/fisiologia , Xilenos/metabolismo , Biofilmes , Gases , Nanofios , Shewanella/metabolismo
4.
Chemosphere ; 250: 126324, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32135441

RESUMO

Human exposure to formaldehyde, toluene, xylene (FTX) and other volatile organic compounds (VOCs) are associated with negative health impact. To characterize the exposure and health effects of FTX and TVOC from indoor environments, we conducted an extensive monitoring campaign involving 1278 measurements of 472 indoor locations in Harbin, a megacity in China from May 2013 to March 2018. The results showed that household had the highest mean formaldehyde concentration (0.171 ± 0.084 mg m-3) among all types of indoor environments. Meanwhile, there was no significant differences in formaldehyde concentration of the living room, master bedroom, secondary bedroom and study room (p > 0.05), as well as toluene and xylene. The highest mean concentration of toluene, xylene and TVOC was measured in public bath center. Great difference was found between formaldehyde concentrations in 2013 and other years, except 2015. There were great positive nonlinear correlations between the indoor temperature and concentration of formaldehyde (p < 0.01), good negative nonlinear correlations between the finish time of decoration and concentration of formaldehyde (p < 0.01), good positive linear correlations between the relative humidity and concentration of formaldehyde (p < 0.01). A risk assessment methodology was utilized to evaluate the potential adverse health effects of the individual FTX compounds according to their carcinogenicities. The predicted carcinogenic risk of formaldehyde was greater than the threshold value 1E-06 at all environments. The non-carcinogenic risk of TX compounds in the population is negligible. For estimating human health risk exposure, sensitivity analysis showed that more attention should be given to the influential variables such as the level of pollutants.


Assuntos
Poluição do Ar em Ambientes Fechados/análise , Monitoramento Ambiental/métodos , Compostos Orgânicos Voláteis/análise , Poluentes Atmosféricos/análise , Poluição do Ar em Ambientes Fechados/estatística & dados numéricos , China , Formaldeído/análise , Humanos , Medição de Risco , Tolueno/análise , Xilenos/análise
5.
Chemosphere ; 242: 125281, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896191

RESUMO

In this study, the potential of pulverized waste tires (PWTs), either on their own or mixed with soil (well graded sand), to act as adsorptive fill materials was evaluated by conducting laboratory tests for accessing their adsorption and geotechnical properties. PWT (0, 5, 10, 15, 25, and 100 wt%) was mixed with soil to evaluate the removal of benzene, toluene, ethylbenzene, and xylene (BTEX) components and two heavy metal ions (Pb2+ and Cu2+). Adsorption batch tests were performed to determine the equilibrium sorption capacity of each mixture. Subsequently, compaction, direct shear, and consolidation tests were performed to establish their geotechnical properties. The results showed that BTEX had the strongest affinity based on the uptake capacity by the soil-PWT mixtures. The adsorption of BTEX increased for greater PWT content, with pure PWT having the highest adsorption capacity toward BTEX removal: uptake capacities for xylene, ethylbenzene, toluene, and benzene were 526, 377, 207 and 127 µg/g sorbent, respectively. Heavy metal removal was increased by increasing the amount of PWT up to 10 wt%, and then decreased beyond this ratio. Compacted soil-PWT mixtures comprising 5-25 wt% PWT have relatively low dry unit weight, low compressibility, adequate shear capacity for many load-bearing field applications, and satisfactory adsorption of organic/inorganic contaminants, such that they could also be used as adsorptive fill materials.


Assuntos
Derivados de Benzeno/análise , Metais Pesados/análise , Poluentes do Solo/análise , Resíduos Sólidos/análise , Adsorção , Benzeno/análise , Modelos Teóricos , Eliminação de Resíduos , República da Coreia , Solo/química , Tolueno/análise , Xilenos/análise
6.
Chemosphere ; 246: 125722, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31891849

RESUMO

Modeling approaches have been utilized to simulate ambient pollutant concentrations, but very limited efforts have been made to estimate volatile organic compounds in the atmosphere. For this reason, an hourly grid-scale simulation model was developed to determine ambient air concentrations of benzene, toluene, ethylbenzene, and xylene (BTEX). BTEX data were collected over a one-year time frame from the database of the Taiwan Environmental Protection Administration's photochemical assessment monitoring stations. Multivariate linear regression models were used along with correlation analysis to simulate hourly grid-scale BTEX concentrations, using criteria pollutants and selected meteorological variables as predictors. The simulation model was validated in the southern Taiwan area via a portable micro gas chromatography system (n = 121) with significant correlation (r = 0.566**, ** indicated p < 0.01). Moreover, the grid-scale model was applied to areas covering about 72% of the population in Taiwan. A geographic information system (GIS) was used to visualize the spatial distribution of BTEX concentrations from the modeling results. This new grid-scale modeling strategy, which incorporated the GIS output of the simulated data, provides a useful alternative tool for personal exposure analysis and health risk assessment of ambient air BTEX.


Assuntos
Monitoramento Ambiental/métodos , Modelos Químicos , Poluentes Atmosféricos/análise , Atmosfera/análise , Benzeno/análise , Derivados de Benzeno/análise , Sistemas de Informação Geográfica , Humanos , Modelos Lineares , Taiwan , Tolueno/análise , Compostos Orgânicos Voláteis/análise , Xilenos/análise
7.
Chemosphere ; 246: 125769, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31918090

RESUMO

Land Use Regression models (LUR) are the most common tools to estimate intra-urban air pollutant exposure in epidemiological studies. However, number of available and published models in developing and middle up income countries is still scarce. Here, we developed seasonal and overall LUR models for the spatial distribution of benzene, toluene, ethylbenzene and xylene (BTEX) based on 20 monitoring stations and 166 potentially predictive variables (PPVs) in Urmia, Iran. Carcinogenic and non-carcinogenic risks of exposure to BTEX and its sensitivity analysis were assessed using a probabilistic approach. The mean and standard deviation (in brackets) of overall benzene, toluene, ethylbenzene and xylene were 12.83 (16.19), 27.03 (32.00), 4.72 (4.15) and 27.35 (29.36) µg/m3, respectively. In all models the R2 value of LUR models of benzene, toluene, ethylbenzene, xylene and total BTEX ranged from 0.66 to 0.85, 0.61, 0.88, 0.72 to 0.94, 0.75 to 0.84 and 0.67 to 0.93. The root mean square error (RMSE) for leave-one-out cross-validations (LOOCV) for benzene, toluene, ethylbenzene and xylene ranged from 7.48 to 10.31, 23.0 to 30.0, 3.40 to 6.90, 16.27 to 24.49, 36.10-50.0 µg/m3, respectively. The estimated lifetime carcinogenic risk (LTCR) indicated that ambient concentration of benzene is at a risk level for Urmia inhabitants (LTCR >10-6). Sensitivity analysis for LTCR model indicated that concentration of benzene (C) was the most effective variable in increasing the carcinogenic risk (correlation coefficient ranged from 0.97 to 0.98 for all models).


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Benzeno/análise , Derivados de Benzeno/análise , Carcinógenos/análise , Humanos , Irã (Geográfico) , Medição de Risco , Análise Espacial , Tolueno/análise , Xilenos/análise
8.
J Chromatogr A ; 1617: 460840, 2020 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-31948724

RESUMO

Sensitive methods are required for in situ monitoring of volatile organic compounds (VOCs). Herein, carbon nanotube (CNT) sponges were investigated as a new type of adsorbent for enriching trace aromatic VOCs. A square pillar configuration (3 mm × 3 mm × 45 mm, 5 mg) of a CNT sponge was enclosed in a glass tube (4 mm i.d.). After accumulating the sample vapor, a direct current pulse (26 V, 0.5-3.0 s) through the CNT sponge allowed narrow desorption bandwidths of 0.48-0.84 s (with a photoionization detector) and 1.2 s (with a flame ionization detector) and high desorption efficiency (>96.5%). Gas chromatographic analysis of a nine-component VOC mixture (100 mL adsorption volume) gave enrichment factors of 88 (benzene) to 323 (toluene and m-xylene) with detection limits in the range of 0.9-2.6 ppb (v/v). These results demonstrate that CNT sponges are a promising preconcentrator material for trace detection of VOCs. The adsorption breakthrough experiments exhibited good correlation with the kinetic adsorption and Langmuir isotherm models. The maximum adsorption capacities of the CNT sponge increased in the order benzene (0.13 mg/g) < toluene (2.45 mg/g) < ethylbenzene (13.90 mg/g) < o-xylene (14.31 mg/g), with R2 values of >0.95. The rollup phenomena observed during multicomponent adsorption were explained by the competitive displacement or adsorption affinities of aromatic VOCs. The feasibility of the CNT sponge preconcentrator in a real environment was tested for interfering species (NO2 and NH3), laboratory air, and a human breath sample and demonstrated similar performance as in the controlled nine-component tests.


Assuntos
Nanotubos de Carbono/química , Compostos Orgânicos Voláteis/análise , Adsorção , Benzeno/análise , Derivados de Benzeno/análise , Cromatografia Gasosa , Cinética , Tolueno/análise , Xilenos/análise
9.
Environ Sci Pollut Res Int ; 27(1): 837-845, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31813123

RESUMO

Soil contamination with benzene, toluene, ethylbenzene and xylene isomers (BTEX) has raised increasing concern because of its high solubility in water and toxicity to biotic communities. This study aims at investigating the process and prospects of deploying bioelectrochemical system (BES) for the removal of BTEX from artificially contaminated soil using Pseudomonas putida YNS1, alongside the reduction of hexavalent chromium (Cr(VI)). The BES was setup with desired operating conditions: initial concentration of BTEX (50-400 mg/L in 100 mL of sterilized water), pH (4-10) and applied potential voltage (0.6-1.2 V) with 10 µL log-phase culture along with the addition of Cr(VI) (10 mg/L). Samples were collected at regular intervals and analysed for BTEX degradation using gas chromatography and Cr(VI) reduction using UV-Vis spectrophotometer. Under optimized conditions (initial BTEX concentration, 200 mg/L; pH 7; and applied voltage 0.8 V with Cr(VI) of 10 mg/L), 92% of BTEX was degraded and 90% Cr(VI) was reduced from the contaminated soil. The intermediates produced during degradation were analysed through gas chromatography-flame ionization detector (GC-FID), and the possible degradation pathway was elucidated. The results indicated that BES could be effective for simultaneous degradation of BTEX along with Cr(VI) reduction.


Assuntos
Cromo/química , Recuperação e Remediação Ambiental/métodos , Poluentes do Solo/química , Benzeno/análise , Derivados de Benzeno/análise , Cromatografia Gasosa , Isomerismo , Pseudomonas putida/metabolismo , Solo , Microbiologia do Solo , Poluentes do Solo/análise , Tolueno/análise , Xilenos/análise
10.
Food Chem ; 310: 125840, 2020 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-31806390

RESUMO

Despite the extensive use of Polygonum chinense (PC) as a detoxifying ingredient of Chinese cool tea, the efficacy of different PC varieties remains underexplored. Herein, we compare the chemical profiles and antioxidant/anti-inflammatory activities of the aqueous extracts of two PC varieties, namely P. chinense var. chinense (PCC) and P. chinense var. hispidum (PCH). Ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MSMS) and multivariate analysis are used to rapidly identify extract components, while DPPH radical scavenging and xylene-induced mice ear edema assays are used to evaluate antioxidant and anti-inflammatory activities, respectively. Correlation analysis reveals that ellagic acid and quercitrin contents are positively correlated with the magnitude of the anti-inflammatory effect, and the adopted technique is concluded to allow for the rapid discrimination of PC varieties used in Chinese cool tea formulations.


Assuntos
Polygonum/química , Chás de Ervas/análise , Animais , Anti-Inflamatórios/química , Anti-Inflamatórios/farmacologia , Antioxidantes/química , Antioxidantes/farmacologia , China , Cromatografia Líquida de Alta Pressão/estatística & dados numéricos , Ácido Elágico/análise , Qualidade dos Alimentos , Masculino , Camundongos Endogâmicos BALB C , Extratos Vegetais/química , Quercetina/análogos & derivados , Quercetina/análise , Quercetina/farmacologia , Espectrometria de Massas em Tandem , Xilenos/toxicidade
11.
Chemosphere ; 244: 125447, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31805459

RESUMO

In this study, personal exposure to benzene, toluene and xylene as important VOC species of incomplete combustion are assessed, considering the ventilation condition of the rural kitchens throughout the seasons. Annual mean total BTX levels were 148.51, 76.98, 34.91 and 13.34 µgm-3 for the rural kitchens with openness of <25%, 25-50%, 50-75% and >75% respectively. Overall annual mean concentration of benzene, toluene and xylene level was found to be 52.35, 8.85 and 7.23 µgm-3 respectively. Annual mean total BTX was found across the openness of the kitchens to be 68.43 µgm-3. There was no significant interaction between the independent variables 'openness' and 'season' explaining pollution exposure variability. Openness of the kitchens was the only significant predictor for BTX exposure concentration variation. Average daily dose (ADD) analysis showed median value of 1.439 × 10-3 mg/kg-day with 95% certainty range from 9.04 × 10-4 mg/kg-day to 2.220 × 10-3 mg/kg-day. Hazard index (HI) indicates no significant risk of non-carcinogenic effect from the exposure to benzene, toluene and xylene. In ADD and all non-cancerous risk estimates (HQ of benzene, toluene, xylene), exposure time emerges as the single most contributor whereas, annual average pollutant exposure is the second most risk contributor in all the cases. Lifetime cancer risk of benzene exceeded the acceptable level indicating probable cancer risk and inhalation unit risk alone contributes above 75%; exposure time came after with 16.3% contribution.


Assuntos
Biocombustíveis/análise , Culinária , Exposição por Inalação/estatística & dados numéricos , Compostos Orgânicos Voláteis/análise , Benzeno/análise , Feminino , Humanos , Índia , Medição de Risco , População Rural , Estações do Ano , Tolueno/análise , Xilenos/análise
12.
Environ Pollut ; 258: 113793, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31864921

RESUMO

2,6-Dimethylphenol (2,6-DMP), an important chemical intermediate and the monomer of plastic polyphenylene oxide, is widely used in chemical and plastics industry. However, the pollution problem of 2,6-DMP residues is becoming increasingly serious, which is harmful to some aquatic animals. Microbial degradation provided an effective approach to eliminate DMPs in nature, which is considered as a prospective way to remediate DMPs-contaminated environments. But the 2,6-DMP-degrading bacteria is not available and the molecular mechanism of 2,6-DMP degradation is unclear as well. Here, a 2,6-DMP-degrading bacterium named B5-4 was isolated and identified as Mycobacterium neoaurum. M. neoaurum B5-4 could utilize 2,6-DMP as the sole carbon source for growth. Furthermore, M. neoaurum B5-4 could degrade 2,6-DMP with concentrations ranging from 1 to 500 mg L-1. Six intermediate metabolites of 2,6-DMP were identified and a metabolic pathway of 2,6-DMP in M. neoaurum B5-4 was proposed, in which 2,6-DMP was initially converted to 2,6-dimethyl-hydroquinone and 2,6-dimethyl-3-hydroxy-hydroquinone by two consecutive hydroxylations at C-4 and γ position; 2,6-dimethyl-3-hydroxy-hydroquinone was then subjected to aromatic ring ortho-cleavage to produce 2,4-dimethyl-3-hydroxymuconic acid, which was further transformed to citraconate, and subsequently into TCA cycle. In addition, toxicity bioassay of 2,6-DMP in water using zebrafish indicates that 2,6-DMP is toxic to zebrafish and M. neoaurum B5-4 could effectively eliminate 2,6-DMP in water to protect zebrafish from 2,6-DMP-induced death. This work provides a potential strain for bioremediation of 2,6-DMP-contaminated environments and lays a foundation for elucidating the molecular mechanism and genetic determinants of 2,6-DMP degradation.


Assuntos
Biodegradação Ambiental , Mycobacterium/metabolismo , Xilenos/metabolismo , Animais , Estudos Prospectivos
13.
Chemosphere ; 238: 124605, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31450107

RESUMO

A Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) methodology followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis was developed to extract thirteen synthetic musk compounds (SMCs: cashmeran, celestolide, phantolide, traseolide, galaxolide, tonalide, musk ambrette, musk xylene, musk ketone, musk tibetene, musk moskene, ethylene brassylate and exaltolide) and six ultraviolet-filters (UVFs: 2-ethylhexyl 4-dimethylaminobenzoate, 3-(4'-methylbenzylidene) camphor, 2-ethylhexyl 4-methoxycinnamate, 2-ethylhexyl 2-cyano-3,3-diphenylacrylate, benzophenone and drometrizole trisiloxane) from tomatoes. The proposed methodology was optimized: 2 g of freeze-dried tomato was extracted with 4 mL of water and 10 mL of ethyl acetate, adding 6 g of MgSO4 and 1.5 g of NaCl, then a dispersive solid-phase extraction was performed using 3 g of MgSO4, 300 mg of primary-secondary amino adsorbent (PSA) and 300 mg of octadecyl-silica (C18). Validation delivered recoveries between 81 (celestolide) and 119% (musk tibetene), with relative standard deviations <10%. The instrumental limit of detection varied from 0.02 (2-ethylhexyl 4-methoxycinnamate) to 3.00 pg (exaltolide and musk xylene). Regarding the method quantification limits, it ranged between 0.4 (celestolide) and 47.9 ng g-1 dw (exaltolide). The method was applied to different varieties of tomatoes (Solanum lycopersicum), revealing UVFs and SMCs between 1 and 210 ng g-1 dw. Higher concentrations were found for benzophenone (29-210 ng g-1 dw) and galaxolide (9-53 ng g-1 dw). The risk associated to the ingestion of contaminated tomatoes has also been estimated, showing that a potential health risk is unlikely.


Assuntos
Ácidos Graxos Monoinsaturados/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Lycopersicon esculentum/química , Poluentes Químicos da Água/análise , Benzofenonas/análise , Benzopiranos/análise , Dinitrobenzenos/análise , Indanos/análise , Extração em Fase Sólida , Espectrometria de Massas em Tandem , Tetra-Hidronaftalenos/análise , Xilenos/análise
14.
Chemosphere ; 239: 124800, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31526993

RESUMO

Biological degradation of high strength phenol and its derivatives in groundwater is problematic because these compounds are toxic to human and microbes. To evaluate the feasibility of in situ bioremediation using sequential aerobic respiration and heterotrophic denitrification, a field single-well-drift test (SWDT) was conducted in groundwater contaminated with coal tar distillates. To stimulate indigenous phenol degrading microorganisms, a 1400 L of oxygen-saturated test solution containing bromide (3.96 ±â€¯0.179 mmol-Br/L) and nitrate (5.34 ±â€¯0.187 mmol NO3--N/L) was injected into an aquifer. After injection of the test solution, significant consumption of dissolved oxygen (DO) was immediately observed; then, degradation of the methyl derivatives o-cresol and m,p-cresol was observed with average zero-order rate coefficients of 0.047 mmol/L/d and 0.23 mmol/L/d, respectively. After 73% of the injected DO was consumed, significant NO3- consumption was observed along with degradation of phenol and the dimethyl derivatives 2,4-xylenol and 3,5-xylenol, which had average zero-order rate coefficients of 0.17 mmol/L/d, 0.060 mmol/L/d, and 0.018 mmol/L/d, respectively. The production of CO2, NO2-, and N2O along with significant consumption of DO and NO3- suggest that phenolic compounds were biologically degraded by sequential aerobic respiration and heterotrophic denitrification. The results of 16s RNA analysis revealed that, after injection of the test solution, a bacterium that shared a 99% 16s rRNA sequence similarity with an uncultured bacterium revealed to be Pseudomonas stutzeri, a facultative heterotrophic denitrifier, was found in the aquifer. Thus, these results suggest that simultaneous injection of DO and NO3- is an appropriate in situ bioremediation strategy for degrading mixtures of high-strength phenolic compounds in an aquifer.


Assuntos
Água Subterrânea/microbiologia , Fenóis/metabolismo , Poluentes Químicos da Água/metabolismo , Aerobiose , Biodegradação Ambiental , Brometos/metabolismo , Cresóis/química , Cresóis/metabolismo , Desnitrificação , Estudos de Viabilidade , Água Subterrânea/química , Processos Heterotróficos , Humanos , Nitratos/metabolismo , Nitrogênio/metabolismo , Fenóis/química , Pseudomonas stutzeri/genética , Pseudomonas stutzeri/metabolismo , RNA Ribossômico 16S/metabolismo , República da Coreia , Poluentes Químicos da Água/química , Xilenos/química , Xilenos/metabolismo
15.
Chemosphere ; 240: 124906, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31550587

RESUMO

Benzene homologues have significant toxic effects to aquatic organisms. In this study, the acute toxicity data of benzene, toluene, ethylbenzene and xylene (BTEX) were collected and screened, and the toxicity extrapolation model of paired BTEX was established. The results showed that except the correlation between benzene and xylene was not strong due to insufficient data, the linear correlation of the other five paired BTEX was good (p < 0.01), and R2 fitted by the four out of five paired BTEX was greater than 0.85. The cross validation showed that ethylbenzene-xylene model was optimal, and for most species (81.8%), the established five BTEX models had a prediction error of less than 10%. Also, these extrapolation models were validated by experimental results of Pseudorasbora parva. The difference between the predicted and measured values of the acute toxicity of BTEX was less than 1 fold, which indicated that the extrapolation model had high accuracy.


Assuntos
Benzeno/toxicidade , Ecotoxicologia/métodos , Tolueno/toxicidade , Poluentes Químicos da Água/toxicidade , Xilenos/toxicidade , Animais , Organismos Aquáticos , Derivados de Benzeno/toxicidade , Biodegradação Ambiental , Cyprinidae , Modelos Teóricos , Reprodutibilidade dos Testes , Testes de Toxicidade Aguda
16.
Bioresour Technol ; 296: 122335, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31732413

RESUMO

Polyurethane (PU) sponges are popular packing material in biofilters and their smooth and hydrophobic surface often leads to an uneven distribution and detachment of biofilms. In this work, the surface of PU sponge was modified to obtain higher roughness and positive charge. The performances of two biofilters (BF1 with pristine sponge and BF2 with modified sponge) for benzene, toluene, ethylbenzene, and xylene (BTEX) removal were investigated. Total Volatile Organic Compound (TVOC) removal efficiency and CO2 increment were 61% and 804 ppm for BF2 respectively after start-up, compared with 51% and 538 ppm for BF1. Analysis on biofilms showed that the modification of PU sponge significantly improved the microbial growth, viability and adhesive strength in biofilms, reduced extracellular polymeric substance (EPS) and changed the microbial community. These results demonstrate that modified sponge can enhance biofilm formation and BTEX removal in biofilters and may applied in large-scale applications.


Assuntos
Tolueno , Xilenos , Benzeno , Derivados de Benzeno , Biodegradação Ambiental , Biofilmes , Matriz Extracelular de Substâncias Poliméricas
17.
Enzyme Microb Technol ; 133: 109457, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31874687

RESUMO

Highly sensitive in situ-synthesized cadmium sulfide (CdS) nanowires (NWs) for the detection of chemiluminescence in immunoassays with a photoresist (PR) layer to stabilize the CdS NWs before and after coating with a parylene film were developed. The thickness of the PR layer was controlled by adjusting the viscosity of the PR solution used for spin-coating. PR2005 was the optimal PR for passivation of the NW surface. After the addition of a parylene coating on the CdS NWs, the photocurrent increased by as much as 50% over a broad range of light intensities, and the additional PR layer increased the photoresponse over the whole range of light intensities. When the photoresponses of the CdS NWs with and without the parylene film were compared after the addition of a PR layer, significant differences were observed in the photocurrent behavior after the incident light was turned off. For the CdS NWs with a parylene film and PR layer, the photocurrent reached the baseline within milliseconds of the incident light being turned off. However, the CdS NWs without a parylene film but with a PR layer required >60 s to reach the baseline level. This difference was due to the capacitance arising from the contact between the NWs. The in situ-synthesized CdS NW photosensor passivated by the parylene film and a PR layer was used in a chemiluminescence-based immunoassay. Finally, the detection of human immunodeficiency virus antibodies was demonstrated via a chemiluminescent enzyme-linked immunosorbent assay based on the CdS NW photosensor in comparison with the optical-density measurement for the chromogenic reaction of TMB(3,3',5,5'-Tetramethylbenzidine).


Assuntos
Compostos de Cádmio/química , Imunoensaio/instrumentação , Luminescência , Nanofios/química , Sulfetos/química , Polímeros/química , Xilenos/química
18.
J Ethnopharmacol ; 248: 112262, 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-31585162

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Artemisia ordosica Krasch. (AOK) has been used for rheumatic arthritis, cold headache, sore throat, etc. in traditional Chinese/Mongolian medicine and is used for nasosinusitis by local Mongolian "barefoot" doctors. Up to now, their mechanisms are still unclear. AIM: To evaluate the in vivo anti-inflammatory and allergic rhinitis (AR) alleviating effect as well as in vitro antimicrobial activities of AOK extracts to verify its ethno-medicinal claims. MATERIALS AND METHODS: Crude extracts (methanol/95%-ethanol/ethyl acetate) of AOK root/stem/leaf and fractions (petroleum ether/ethyl acetate/n-butanol/aqueous) of AOK root extract were prepared. Xylene-induced ear swelling model in mouse and ovalbumin (OVA)-induced AR model in guinea pig were established. Ear swelling degrees of mice were measured. The numbers of rubbing movement and sneezes of guinea pigs were counted to evaluate the symptoms of AR. The serum levels of histamine, INF-γ, IL-2/4/10, and VCAM-1 were measured by ELISA assay. The histological changes of nasal mucosa were investigated by light microscope after H&E staining. Antimicrobial activities of AOK extracts were also tested. LC-MS/MS analysis was performed to characterize the constituents of active extract and molecular docking was conducted to predict the biological mechanism. RESULTS: In ear-swelling model, extract (100.00 mg/kg) from the ethyl acetate layer of 95% ethanol (100.00 mg/kg) showed better swelling inhibition in mice than positive control (dexamethasone, 191.91 mg/kg). In AR model, extract from the ethyl acetate layer of 95% ethanol significantly alleviated the AR symptoms in guinea pigs, decreased the serum levels of histamine, INF-γ, IL-2/4/10, and VCAM-1, and reduced the infiltration of eosinophil in nasal mucosa. For Staphylococcus aureus, the ethyl acetate extract of AOK stem showed the highest inhibition (MIC=1.25 mg/mL), for Escherichia coli, n-butanol layer of 95% ethanol extract of AOK root showed the highest inhibition (MIC=15.00 mg/mL), for Candida glabrata, 95%-ethyl acetate extract of AOK leaf showed the best inhibition (MIC=0.064 mg/mL), while ethyl acetate and n-butanol layers showed similar inhibition on MRSA (MIC=7.50 mg/mL). LC-MS/MS characterization showed that dicaffeoylquinic acids account for more than 30% of ethyl acetate layer of AOK extract. Dicaffeoylquinic acids bind with histamine-1 receptor with high affinities and interesting modes. CONCLUSIONS: Extracts from AOK had interesting anti-inflammatory activity in mice, alleviating effect against OVA-induced AR in guinea pigs, and antimicrobial activities in vitro, which support the ethno-medicinal use of it. The main constituents in ethyl acetate layer of AOK root extract are dicaffeoylquinic acids and could bind with histamine-1 receptor well. These findings highlighted the importance of natural product chemistry study of AOK.


Assuntos
Antialérgicos/uso terapêutico , Anti-Infecciosos/uso terapêutico , Anti-Inflamatórios/uso terapêutico , Artemisia , Extratos Vegetais/uso terapêutico , Rinite Alérgica/tratamento farmacológico , Sinusite/tratamento farmacológico , Alérgenos , Animais , Antialérgicos/farmacologia , Anti-Infecciosos/farmacologia , Anti-Inflamatórios/farmacologia , Candida glabrata/efeitos dos fármacos , Candida glabrata/crescimento & desenvolvimento , Citocinas/imunologia , Edema/induzido quimicamente , Edema/tratamento farmacológico , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Cobaias , Masculino , Medicina Tradicional Chinesa , Medicina Tradicional da Mongólia , Camundongos , Simulação de Acoplamento Molecular , Mucosa Nasal/efeitos dos fármacos , Mucosa Nasal/patologia , Ovalbumina , Extratos Vegetais/farmacologia , Receptores Histamínicos H1/metabolismo , Rinite Alérgica/imunologia , Rinite Alérgica/patologia , Sinusite/imunologia , Sinusite/patologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Xilenos
19.
Molecules ; 24(24)2019 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-31817955

RESUMO

A capillary column coated with nanostructured silver coating was fabricated for gas chromatography. The nanostructured silver coating, about 80-120 nm in thickness, was prepared as the stationary phase via silver mirror reaction, and was characterized by SEM and EDS. The column was evaluated using different types of model analytes, including n-alkanes, n-alcohols, benzenes, and Grob mixture. A baseline separation of ten n-alkanes on the silver column (15 m × 0.20 mm i.d.) was achieved within 3.5 min through the main hydrophobic mechanism. A mixture of six n-alcohols, or another mixture containing three butanol isomers and two octanol isomers, was separated well on the column. The column separated some benzenes containing benzene, toluene, ethylbenzene, p-xylene, o-xylene, styrene, benzaldehyde, and benzyl alcohol. A Grob mixture containing seven analytes was also separated successfully. Based on a multiple retention mechanism such as hydrophobic, dipole-dipole, and dipole-induced dipole interactions, the silver column achieved a good separation of twelve different types of compounds within 2.5 min. The column presented satisfactory separation repeatability with relative standard deviation of retention time between 0.073% and 0.591%. The results indicate that the silver column is promising for gas chromatographic separation.


Assuntos
Cromatografia Gasosa/métodos , Nanoestruturas/química , Prata/química , Álcoois/química , Alcanos/química , Benzeno/química , Isomerismo , Xilenos/química
20.
Cell Mol Biol (Noisy-le-grand) ; 65(7): 99-104, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31880525

RESUMO

Inflammation and insomnia are medical problems that may severely affect work and health, thereby necessitating strategies for their effective treatment. Icartin (ICT) is a major active monomeric component of icariin  . Studies have revealed that ICT possesses several pharmacological properties such anti-inflammatory, anti-tumor, anti-fibrotic, anti-osteoporotic and neuroprotective effects. The present research was carried out to investigate the anti-inflammatory, analgesic and sedative/hypnotic effects of ICT. The results obtained revealed that ICT exerted a good anti-inflammatory effect related to the downregulations of inflammatory cytokines and the inhibition of COX-2 signaling pathway. Moreover, ICT enhanced Cl- influx in mouse cortical cells in a concentration-dependent manner. These data suggest that ICT exerts a hypnotic effect in mice through a mechanism associated with increased Cl- influx in cortical cells.


Assuntos
Analgésicos/uso terapêutico , Anti-Inflamatórios/uso terapêutico , Encéfalo/metabolismo , Cloretos/metabolismo , Flavonoides/uso terapêutico , Hipnóticos e Sedativos/uso terapêutico , Inflamação/tratamento farmacológico , Animais , Encéfalo/efeitos dos fármacos , Ciclo-Oxigenase 2/metabolismo , Orelha/patologia , Feminino , Inflamação/induzido quimicamente , Masculino , Camundongos , Pentobarbital/uso terapêutico , Transdução de Sinais/efeitos dos fármacos , Sono/efeitos dos fármacos , Latência do Sono/efeitos dos fármacos , Xilenos/toxicidade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA