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Soil humic-like organic compounds in prescribed fire emissions using nuclear magnetic resonance spectroscopy Texte intégral
2013
Chalbot, M.-C. | Nikolich, G. | Etyemezian, V. | Dubois, D.W. | King, J. | Shafer, D. | Gamboa da Costa, G. | Hinton, J.F. | Kavouras, I.G.
Here we present the chemical characterization of the water-soluble organic carbon fraction of atmospheric aerosol collected during a prescribed fire burn in relation to soil organic matter and biomass combustion. Using nuclear magnetic resonance spectroscopy, we observed that humic-like substances in fire emissions have been associated with soil organic matter rather than biomass. Using a chemical mass balance model, we estimated that soil organic matter may contribute up to 41% of organic hydrogen and up to 27% of water-soluble organic carbon in fire emissions. Dust particles, when mixed with fresh combustion emissions, substantially enhances the atmospheric oxidative capacity, particle formation and microphysical properties of clouds influencing the climatic responses of atmospheric aeroso. Owing to the large emissions of combustion aerosol during fires, the release of dust particles from soil surfaces that are subjected to intense heating and shear stress has, so far, been lacking.
Afficher plus [+] Moins [-]Identification of soil bacteria able to degrade phenanthrene bound to a hydrophobic sorbent in situ Texte intégral
2013
Regonne, Raïssa Kom | Martin, Florence | Mbawala, Augustin | Ngassoum, Martin Benoît | Jouanneau, Yves
Efficient bioremediation of PAH-contaminated sites is limited by the hydrophobic character and poor bioavailability of pollutants. In this study, stable isotope probing (SIP) was implemented to track bacteria that can degrade PAHs adsorbed on hydrophobic sorbents. Temperate and tropical soils were incubated with 13C-labeled phenanthrene, supplied by spiking or coated onto membranes. Phenanthrene mineralization was faster in microcosms with PAH-coated membranes than in microcosms containing spiked soil. Upon incubation with temperate soil, phenanthrene degraders found in the biofilms that formed on coated membranes were mainly identified as Sphingomonadaceae and Actinobacteria. In the tropical soil, uncultured Rhodocyclaceae dominated degraders bound to membranes. Accordingly, ring-hydroxylating dioxygenase sequences recovered from this soil matched PAH-specific dioxygenase genes recently found in Rhodocyclaceae. Hence, our SIP approach allowed the detection of novel degraders, mostly uncultured, which differ from those detected after soil spiking, but might play a key role in the bioremediation of PAH-polluted soils.
Afficher plus [+] Moins [-]Passive air sampling of organochlorine pesticides and polychlorinated biphenyls in the Yangtze River Delta, China: Concentrations, distributions, and cancer risk assessment Texte intégral
2013
Zhang, Lifei | Dong, Liang | Yang, Wenlong | Zhou, Li | Shi, Shuangxin | Zhang, Xiulan | Niu, Shan | Li, Lingling | Wu, Zhongxiang | Huang, Yeru
The Yangtze River Delta (YRD) has been quickly industrialized and urbanized. Passive air sampling of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) was carried out in the YRD in 2010–2011 to investigate their spatiotemporal distributions and estimate the risk of cancer from their inhalation. Annual concentrations were 151, 168, 18.8, 110, 17.9, and 35.0 pg m−3 for HCB, ∑DDTs, ∑HCHs, ∑chlordane, mirex, and PCBs, respectively. The highest OCP and PCB concentrations were generally detected in the autumn and winter. The average concentrations of OCPs and PCBs for the different site groups followed the order urban ≈ urban–rural transition > rural. The lifetime excess cancer risks from the inhalation of OCPs and PCBs were <1.0 × 10−6. The predicted cancer cases per lifetime associated with the inhalation of OCPs and PCBs are 12, 7, and 4 per ten thousand people for urban, urban–rural transition, and rural areas, respectively.
Afficher plus [+] Moins [-]New insights into parental effects and toxicity: Mate availability and diet in the parental environment affect offspring responses to contaminants Texte intégral
2013
Plautz, Stephanie C. | Funkhouser, Meghan A. | Salice, Christopher J.
Parental effects manifest as alterations in offspring phenotype resulting from the parental phenotype and/or parental environment. We evaluated the effects of parental diet quality and mating strategy on the toxicant tolerance of offspring in Biomphalaria glabrata snails. We raised snails either individually (self-fertilizing) or in groups of three (outcrossing) on a diet of uncooked lettuce, fish food, cooked lettuce, or cooked lettuce plus fish food. We then exposed their offspring to cadmium and malathion challenges. Cadmium tolerance varied with parental diet and was greater in the offspring of outcrossing snails than self-fertilizing snails. Malathion tolerance was not affected by parental diet but was greater in the offspring of outcrossing snails. These results indicate that offspring responses to stressors are heavily influenced by parental experience, but may depend on the specific stressor and the mechanism of action and/or detoxification.
Afficher plus [+] Moins [-]Toxic effects of erythromycin, ciprofloxacin and sulfamethoxazole exposure to the antioxidant system in Pseudokirchneriella subcapitata Texte intégral
2013
Nie, Xiang-Ping | Liu, Bin-Yang | Yu, Hui-Juan | Liu, Wei-Qiu | Yang, Yu-Feng
We tested antioxidant responses of the green microalga Pseudokirchneriella subcapitata exposed to different concentrations of the three antibiotics erythromycin (ETM), ciprofloxacin (CPF) and sulfamethoxazole (SMZ). Measurements included the level of lipid peroxidation, the total antioxidative capacity and three major antioxidant mechanisms: the ascorbate–glutathione cycle, the xanthophyll cycle and the enzyme activities of catalase (CAT), superoxide dismutase (SOD), guaiacol glutathione peroxidase (GPX) and glutathione-S-transferase (GST). Three antibiotics significantly affect the antioxidant system of P. subcapitata, but in different ways the alga was more tolerant to CPF and SMZ exposures than to ETM exposure. ETM caused reductions in AsA and GSH biosynthesis, ascorbate–glutathione cycle, xanthophylls cycle and antioxidant enzyme activities. The toxicity of CPF seems to be mainly overcome via induction of the ascorbate–glutathione cycle and CAT, SOD and GPX activities, while the toxicity of SMZ on the photosynthetic apparatus is predominantly reduced by the xanthophyll cycle and GST activity.
Afficher plus [+] Moins [-]New approach to the ecotoxicological risk assessment of artificial outdoor sporting grounds Texte intégral
2013
Krüger, O. | Kalbe, U. | Richter, E. | Egeler, P. | Römbke, J. | Berger, W.
Artificial surfaces for outdoor sporting grounds may pose environmental and health hazards that are difficult to assess due to their complex chemical composition. Ecotoxicity tests can indicate general hazardous impacts. We conducted growth inhibition (Pseudokirchneriella subcapitata) and acute toxicity tests (Daphnia magna) with leachates obtained from batch tests of granular infill material and column tests of complete sporting ground assemblies. Ethylene propylene diene monomer rubber (EPDM) leachate showed the highest effect on Daphnia magna (EC50 < 0.4% leachate) and the leachate of scrap tires made of styrene butadiene rubber (SBR) had the highest effect on P. subcapitata (EC10 = 4.2% leachate; EC50 = 15.6% leachate). We found no correlations between ecotoxicity potential of leachates and zinc and PAH concentrations. Leachates obtained from column tests revealed lower ecotoxicological potential. Leachates of column tests of complete assemblies may be used for a reliable risk assessment of artificial sporting grounds.
Afficher plus [+] Moins [-]Beyond the bed: Effects of metal contamination on recruitment to bedded sediments and overlying substrata Texte intégral
2013
Hill, Nicole A. | Simpson, Stuart L. | Johnston, Emma L.
Metal-contaminated sediments pose a recognised threat to sediment-dwelling fauna. Re-mobilisation of contaminated sediments however, may impact more broadly on benthic ecosystems, including on diverse assemblages living on hard substrata patches immediately above sediments. We used manipulative field experiments to simultaneously test for the effects of metal contamination on recruitment to marine sediments and overlying hard substrata. Recruitment to sediments was strongly and negatively affected by metal contamination. However, while assemblage-level effects on hard-substratum fauna and flora were observed, most functional groups were unaffected or slightly enhanced by exposure to contaminated sediments. Diversity of hard-substratum fauna was also enhanced by metal contamination at one site. Metal-contaminated sediments appear to pose less of a hazard to hard-substratum than sediment-dwelling assemblages, perhaps due to a lower direct contaminant exposure or to indirect effects mediated by contaminant impacts on sediment fauna. Our results indicate that current sediment quality guidelines are protective of hard-substrata organisms.
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 [-]Transformation of four silver/silver chloride nanoparticles during anaerobic treatment of wastewater and post-processing of sewage sludge Texte intégral
2013
Lombi, Enzo | Donner, Erica | Taheri, Shima | Tavakkoli, Ehsan | Jämting, Åsa K. | McClure, Stuart | Naidu, R. | Miller, Bradley W. | Scheckel, Kirk G. | Vasilev, Krasimir
Transformation of four silver/silver chloride nanoparticles during anaerobic treatment of wastewater and post-processing of sewage sludge Texte intégral
2013
Lombi, Enzo | Donner, Erica | Taheri, Shima | Tavakkoli, Ehsan | Jämting, Åsa K. | McClure, Stuart | Naidu, R. | Miller, Bradley W. | Scheckel, Kirk G. | Vasilev, Krasimir
The increasing use of silver (Ag) nanoparticles [containing either elemental Ag (Ag-NPs) or AgCl (AgCl-NPs)] in commercial products such as textiles will most likely result in these materials reaching wastewater treatment plants. Previous studies indicate that a conversion of Ag-NPs to Ag2S is to be expected during wastewater transport/treatment. However, the influence of surface functionality, the nature of the core structure and the effect of post-processing on Ag speciation in sewage sludge/biosolids has not been investigated. This study aims at closing these knowledge gaps using bench scale anaerobic digesters spiked with Ag nitrate, three different types of Ag-NPs, and AgCl-NPs at environmentally realistic concentrations. The results indicate that neither surface functionality nor the different compositions of the NP prevented the formation of Ag2S. Silver sulfides, unlike the sulfides of other metals present in sewage sludge, were stable over a six month period simulating composting/stockpiling.
Afficher plus [+] Moins [-]Transformation of four silver/silver chloride nanoparticles during anaerobic treatment of wastewater and post-processing of sewage sludge Texte intégral
2013
Lombi, E. | Donner, E. | Taheri, S. | Tavakkoli, E. | Jämting, A. | McClure, S. | Naidu, R. | Miller, B. | Scheckel, K. | Vasilev, K.
Abstract not available. | Enzo Lombi, Erica Donner, Shima Taheri, Ehsan Tavakkoli, Åsa K. Jämting, Stuart McClure, Ravi Naidu, Bradley W. Miller, Kirk G. Scheckel, Krasimir Vasilev
Afficher plus [+] Moins [-]Methodology for setup and data processing of mobile air quality measurements to assess the spatial variability of concentrations in urban environments Texte intégral
2013
Van Poppel, Martine | Peters, Jan | Bleux, Nico
A case study is presented to illustrate a methodology for mobile monitoring in urban environments. A dataset of UFP, PM2.5 and BC concentrations was collected. We showed that repeated mobile measurements could give insight in spatial variability of pollutants at different micro-environments in a city. Streets of contrasting traffic intensity showed increased concentrations by a factor 2–3 for UFP and BC and by <10% for PM2.5. The first quartile (P25) of the mobile measurements at an urban background zone seems to be good estimate of the urban background concentration. The local component of the pollutant concentrations was determined by background correction. The use of background correction reduced the number of runs needed to obtain representative results. The results presented, are a first attempt to establish a methodology for setup and data processing of mobile air quality measurements to assess the spatial variability of concentrations in urban environments.
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