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Résultats 121-130 de 1,956
Pro-inflammatory effects and oxidative stress in lung macrophages and epithelial cells induced by ambient particulate matter Texte intégral
2013
Michael, S. | Montag, M. | Dott, W.
The objective of this study was to compare the toxicological effects of different source-related ambient PM10 samples in regard to their chemical composition. In this context we investigated airborne PM from different sites in Aachen, Germany. For the toxicological investigation human alveolar epithelial cells (A549) and murine macrophages (RAW264.7) were exposed from 0 to 96 h to increasing PM concentrations (0–100 μg/ml) followed by analyses of cell viability, pro-inflammatory and oxidative stress responses. The chemical analysis of these particles indicated the presence of 21 elements, water-soluble ions and PAHs. The toxicological investigations of the PM10 samples demonstrated a concentration- and time-dependent decrease in cell viability and an increase in pro-inflammatory and oxidative stress markers.
Afficher plus [+] Moins [-]1-D and 2-D NMR-based metabolomics of earthworms exposed to endosulfan and endosulfan sulfate in soil Texte intégral
2013
Yuk, Jimmy | Simpson, Myrna J. | Simpson, Andre J.
One-dimensional (1-D) and two-dimensional (2-D) nuclear magnetic resonance (NMR)-based metabolomics was used to investigate the toxic mode of action (MOA) of endosulfan, an organochlorine pesticide, and its degradation product, endosulfan sulfate, to Eisenia fetida earthworms in soil. Three soil concentrations (0.1, 1.0 and 10.0 mg/kg) were used for both endosulfan and endosulfan sulfate. Both earthworm coelomic fluid (CF) and tissues were extracted and then analyzed using 1H and 1H–13C NMR techniques. A similar separation trajectory was observed for endosulfan and endosulfan sulfate-exposed earthworms in the mean principal component analysis (PCA) scores plot for both the earthworm CF and tissue extracts.A neurotoxic and apoptotic MOA was postulated for both endosulfan and endosulfan sulfate exposed earthworms as significant fluctuations in glutamine/GABA–glutamate cycle metabolites and spermidine were detected respectively. This study highlights the application of NMR-based metabolomics to understand molecular-level toxicity of persistent organochlorine pesticides and their degradation products directly in soil.
Afficher plus [+] Moins [-]Filling the gap: Estimating physicochemical properties of the full array of polybrominated diphenyl ethers (PBDEs) Texte intégral
2013
Yue, Chaoyang | Li, Loretta Y.
Physicochemical properties of PBDE congeners are important for modeling their transport, but data are often missing. The quantitative structure–property relationship (QSPR) approach is utilized to fill this gap. Individual research groups often report piecemeal properties through experimental measurements or estimation techniques, but these data seldom satisfy fundamental thermodynamic relationships because of errors. The data then lack internal consistency and cannot be used directly in environmental modeling. This paper critically reviews published experimental data to select the best QSPR models, which are then extended to all 209 PBDE congeners. Properties include aqueous solubility, vapor pressure, Henry's law constant, octanol–water partition coefficient and octanol–air partition coefficient. Their values are next adjusted to satisfy fundamental thermodynamic equations. The resulting values then take advantage of all measurements and provide quick references for modeling and PBDE-contaminated site assessment and remediation. PCBs are also compared with respect to their properties and estimation methods.
Afficher plus [+] Moins [-]Using SPME fibers and Tenax to predict the bioavailability of pyrethroids and chlorpyrifos in field sediments Texte intégral
2013
Harwood, Amanda D. | Landrum, Peter F. | Weston, Donald P. | Lydy, Michael J.
The presence of pyrethroids in both urban and agricultural sediments at levels lethal to invertebrates has been well documented. However, variations in bioavailability among sediments make accurate predictions of toxicity based on whole sediment concentrations difficult. A proposed solution to this problem is the use of bioavailability-based estimates, such as solid phase microextraction (SPME) fibers and Tenax beads. This study compared three methods to assess the bioavailability and ultimately toxicity of pyrethroid pesticides including field-deployed SPME fibers, laboratory-exposed SPME fibers, and a 24-h Tenax extraction. The objective of the current study was to compare the ability of these methods to quantify the bioavailable fraction of pyrethroids in contaminated field sediments that were toxic to benthic invertebrates. In general, Tenax proved a more sensitive method than SPME fibers and a correlation between Tenax extractable concentrations and mortality was observed.
Afficher plus [+] Moins [-]Polychlorinated biphenyls in surface soil in urban and background areas of Mongolia Texte intégral
2013
Mamontova, Elena A. | Mamontov, Alexander A. | Tarasova, Eugenia N. | Kuzmin, Mikhail I. | Ganchimeg, Darmaa | Khomutova, Marina Yu | Gombosuren, Odontuya | Ganjuurjav, Erdenebayasgalan
Polychlorinated biphenyls (PCBs) were measured in soil in some industrial towns (Ulaanbaatar, Suhbaatar, Erdenet, Darhan, Tsetserleg, Hovd, Ulaangom, Altay, Bayanhongor, Arvayheer, Saynshand, Choybalsan) and in background and rural areas of Mongolia. The average sum of all investigated PCB congeners in soil of Mongolia comes to 7.4 ng/g dry weight (DW) and varies from 0.53 ng/g DW till 114 ng/g DW. PCB levels in soil from towns are significantly higher than those in soil from background and rural areas. The PCB homological composition in soil sampled in highly-PCB-polluted sites is similar to the PCB homological pattern in Sovol and Aroclor 1254. Significant correlation between soil organic carbon and low chlorinated PCB both for towns and background sites was found. Significant differences in PCB means in soil in different natural zones were found.
Afficher plus [+] Moins [-]Supercritical fluid extraction of persistent organic pollutants from natural and artificial soils and comparison with bioaccumulation in earthworms Texte intégral
2013
Bielská, Lucie | Šmídová, Klára | Hofman, Jakub
Selective supercritical fluid extraction (SSFE) was used as a measurement of compound chemical accessibility and as a predictor of compound bioavailability from three natural soils and artificial analogues prepared to have comparable total organic carbon content. Soils spiked with phenanthrene, pyrene, PCB 153, lindane, and p,p′-DDT were aged for 0, 14, 28, or 56 days and then selectively extracted by supercritical fluid extraction. Compounds exhibited decreasing extractability with increasing pollutant–soil contact time and increasing total organic carbon content in tested soils. However, the different extractability of compounds from artificial and natural pairs having comparable TOC indicates the limitations of using TOC as an extrapolation basis between various soils. The comparison of extractability with bioaccumulation by earthworms (Eisenia fetida) previously published by Vlčková and Hofman (2012) showed that only for PAHs it was possible to predict their bioaccumulation by means of selective SFE.
Afficher plus [+] Moins [-]Enhancement of water solubility and mobility of phenanthrene by natural soil nanoparticles Texte intégral
2013
Li, Wenyan | Zhu, Xinyu | He, Yan | Xing, Baoshan | Xu, Jianming | Brookes, Philip C.
Nanoparticles (NPs) in soils may participate in essential ecological services, since they have special characteristics arising from their nanoscale sizes and large surface areas. We did aqueous solubility enhancement experiments to derive the partition coefficients of phenanthrene between water and six natural soil NPs. The coefficients were approximately exponentially reduced with increasing concentrations of NPs, low concentrations of NPs (50 mg L−1) had significant high adsorption capacities for phenanthrene. Further experiments based on dynamic light scattering technique and column tests were performed to examine the aggregation and mobility of soil NPs and how they influence phenanthrene mobility in porous media. NPs have high and reversible adsorption on surfaces of porous media with aggregation taking place during their transport and they largely control the mobility of phenanthrene in sand columns.
Afficher plus [+] Moins [-]Lead bioaccessibility in topsoils from lead mineralisation and urban domains, UK Texte intégral
2013
Appleton, J.D. | Cave, M.R. | Palumbo-Roe, B. | Wragg, J.
Predictive linear regression (LR) modelling indicates that total Pb is the only highly significant independent variable for estimating Pb bioaccessibility in “mineralisation domains” located in limestone (high pH) and partly peat covered (low pH) shale-sandstone terrains in England. Manganese is a significant minor predictor in the limestone terrain, whilst organic matter and sulphur explain 0.5% and 2% of the variance of bioaccessible Pb in the peat-shale-sandstone terrain, compared with 93% explained by total Pb. Bootstrap resampling shows that LR confidence limits overlap for the two mineralised terrains but the limestone terrain has a significantly lower bioaccessible Pb to total Pb slope than the urban domain. A comparison of the absolute values of stomach and combined stomach-intestine bioaccessibility provides some insight into the geochemical controls on bioaccessibility in the contrasting soil types.
Afficher plus [+] Moins [-]Short- and long-term temporal changes in soil concentrations of selected endocrine disrupting compounds (EDCs) following single or multiple applications of sewage sludge to pastures Texte intégral
2013
Rhind, S.M. | Kyle, C.E. | Ruffie, H. | Calmettes, E. | Osprey, M. | Zhang, Z.L. | Hamilton, D. | McKenzie, C.
Temporal changes in soil burdens of selected endocrine disrupting compounds were determined following application to pasture of either sewage sludge or inorganic fertilizer. Soil polycyclic aromatic hydrocarbon and polychlorinated biphenyl concentrations were not altered. Changes in concentrations of diethylhexyl phthalate (DEHP) and PBDEs 47 and 99 differed with season but concentrations remained elevated for more than three weeks after application, when grazing animals are normally excluded from pasture. It is concluded that single applications of sewage sludge can increase soil concentrations of some, but not all classes of EDCs, possibly to concentrations sufficient to exert biological effects when different chemicals act in combination, but patterns of change depend on season and soil temperature. Analysis of soil from pasture subjected to repeated sludge applications, over 13 years, provided preliminary evidence of greater increases in soil burdens of all of the EDC groups measured, including all of the PBDE congeners measured.
Afficher plus [+] Moins [-]Characterization and influence of biochars on nitrous oxide emission from agricultural soil Texte intégral
2013
Wang, Zhenyu | Zheng, Hao | Luo, Ye | Deng, Xia | Herbert, Stephen | Xing, Baoshan
Extensive use of biochar to mitigate N2O emission is limited by the lack of understanding on the exact mechanisms altering N2O emissions from biochar-amended soils. Biochars produced from giant reed were characterized and used to investigate their influence on N2O emission. Responses of N2O emission varied with pyrolysis temperature, and the reduction order of N2O emission by biochar (BC) was: BC200 ≈ BC600 > BC500 ≈ BC300 ≈ BC350 > BC400. The reduced emission was attributed to enhanced N immobilization and decreased denitrification in the biochar-amended soils. The remaining polycyclic aromatic hydrocarbons (PAHs) in low-temperature biochars (300–400 °C) played a major role in reducing N2O emission, but not for high-temperature biochars (500–600 °C). Removal of phenolic compounds from low-temperature (200–400 °C) biochars resulted in a surprising reduction of N2O emission, but the mechanism is still unknown. Overall, adding giant reed biochars could reduce N2O evolution from agricultural soil, thus possibly mitigating global warming.
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