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Résultats 1951-1960 de 3,208
Factors affecting the accumulation of perfluoroalkyl substances in human blood Texte intégral
2015
Gómez-Canela, Cristian | Fernández-Sanjuan, María | Farrés, Mireia | Lacorte, Silvia
The aim of this study is to evaluate the presence of perfluoroalkyl substances (PFASs) in the blood of 46 residents from Barcelona and to study the factors that affect exposure. Compounds analysed included perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorobutane sulfonate (PFBS), perfluorooctanoate acid (PFOA) and perfluorononanoate acid (PFNA). Blood was liquid–liquid extracted and PFASs were determined by liquid chromatography coupled to tandem mass spectrometry. Good recoveries (between 97 ± 14 and 105 ± 13 %) were obtained and method detection limits were from 0.03 to 0.07 ng mL⁻¹. ΣPFASs ranged from 0.11 to 4.37 ng mL⁻¹. PFOS was the main compound detected at 0.09–3.35 ng mL⁻¹, followed by PFOA and PFHxS. PFBS and PFNA were seldom detected. Working conditions, smoking and gender did not cause any significant differences among ΣPFASs levels in the blood while age and parity produced decreased concentrations. On the other hand, laboratory working conditions produced significant higher PFOA levels compared to the general population. Compared to other studies, the PFASs levels in blood from Barcelona residents is low (mean ΣPFASs of 1.67 ± 0.88 ng mL⁻¹) and with little variation among the studied population.
Afficher plus [+] Moins [-]Kinetics of the degradation of n-butyl benzyl phthalate using O3/UV, direct photolysis, direct ozonation and UV effects Texte intégral
2015
Lovato, María E. | Gilliard, María B. | Cassano, Alberto E. | Martín, Carlos A.
The aim of this work is to study the degradation kinetics of the endocrine disruptor benzyl butyl phthalate using ozone and UV radiation. The model comprises four parallel subsystems that are identified and isolated: (1) direct photolysis, (2) direct ozonation in the absence of hydroxyl radicals, (3) complete ozonation (direct + indirect oxidation), and (4) ozone + UV. To determine the nature of ozone attacks and the influence of ·OH radicals on O₃activity, two sets of experiments were performed: (i) conventional ozonation and (ii) the same ozonation experiments in the presence of tert-butanol as radical scavenger, where only the reactions involving molecular ozone are present. The explored variables were (i) ozone concentration, (ii) incident radiation rate at the reactor windows, (iii) reaction pH, and (iv) the presence of radical scavengers. Major intermediates of BBP degradation were identified. Degradation kinetics was correctly modeled by a pseudo-second-order kinetic model based on the sum of all the effects occurring during the treatment. The corresponding kinetic constants were obtained, and the relative contributions of each of the considered subsystems were evaluated.
Afficher plus [+] Moins [-]Response of plasma membrane H+-ATPase in rice (Oryza sativa) seedlings to simulated acid rain Texte intégral
2015
Liang, Chanjuan | Ge, Yuqing | Su, Lei | Bu, Jinjin
Understanding the adaptation of plants to acid rain is important to find feasible approaches to alleviate such damage to plants. We studied effects of acid rain on plasma membrane H⁺-ATPase activity and transcription, intracellular H⁺, membrane permeability, photosynthetic efficiency, and relative growth rate during stress and recovery periods. Simulated acid rain at pH 5.5 did not affect plasma membrane H⁺-ATPase activity, intracellular H⁺, membrane permeability, photosynthetic efficiency, and relative growth rate. Plasma membrane H⁺-ATPase activity and transcription in leaves treated with acid rain at pH 3.5 was increased to maintain ion homeostasis by transporting excessive H⁺ out of cells. Then intracellular H⁺ was close to the control after a 5-day recovery, alleviating damage on membrane and sustaining photosynthetic efficiency and growth. Simulated acid rain at pH 2.5 inhibited plasma membrane H⁺-ATPase activity by decreasing the expression of H⁺-ATPase at transcription level, resulting in membrane damage and abnormal intracellular H⁺, and reduction in photosynthetic efficiency and relative growth rate. After a 5-day recovery, all parameters in leaves treated with pH 2.5 acid rain show alleviated damage, implying that the increased plasma membrane H⁺-ATPase activity and its high expression were involved in repairing process in acid rain-stressed plants. Our study suggests that plasma membrane H⁺-ATPase can play a role in adaptation to acid rain for rice seedlings.
Afficher plus [+] Moins [-]Morphological alterations in the liver of yellow perch (Perca flavescens) from a biological mercury hotspot Texte intégral
2015
Müller, Anne-Katrin | Brinkmann, Markus | Baumann, Lisa | Stoffel, Michael H. | Segner, H. (Helmut) | Kidd, Karen A. | Hollert, Henner
Mercury (Hg) contamination is a global issue due to its anthropogenic release, long-range transport, and deposition in remote areas. In Kejimkujik National Park and National Historic Site, Nova Scotia, Canada, high concentrations of total mercury (THg) were found in tissues of yellow perch (Perca flavescens). The aim of this study was to evaluate a possible relationship between THg concentrations and the morphology of perch liver as a main site of metal storage and toxicity. Yellow perch were sampled from five lakes known to contain fish representing a wide range in Hg concentrations in fall 2013. The ultrastructure of hepatocytes and the distribution of Hg within the liver parenchyma were analyzed by transmission electron microscopy (TEM) and electron energy loss spectrometry (EELS). The relative area of macrophage aggregates (MAs) in the liver was determined using image analysis software and fluorescence microscopy. No relation between general health indicators (Fulton’s condition index) and THg was observed. In line with this, TEM examination of the liver ultrastructure revealed no prominent pathologies related to THg accumulation. However, a morphological parameter that appeared to increase with muscle THg was the relative area of MAs in the liver. The hepatic lysosomes appeared to be enlarged in samples with the highest THg concentrations. Interestingly, EELS analysis revealed that the MAs and hepatic lysosomes contained Hg.
Afficher plus [+] Moins [-]Arsenic, heavy metals, phthalates, pesticides, hydrocarbons and polyfluorinated compounds but not parabens or phenols are associated with adult remembering condition: US NHANES, 2011–2012 Texte intégral
2015
Shiue, Ivy
Links between environmental chemicals and human health have emerged, but the effects on cognition were less studied. Therefore, it was aimed to study the relationships of different sets of environmental chemicals and the remembering condition in a national and population-based study in recent years. Data was retrieved from the US National Health and Nutrition Examination Surveys, 2011–2012, including demographics, blood pressure readings, serum measurements, lifestyle factors, self-reported remembering condition and urinary environmental chemical concentrations. Analyses included Chi-square test, t test and survey-weighted logistic and multi-nominal regression models. Among the elderly aged 60–80 (n = 1791), 320 (17.9 %) had difficulties in thinking or remembering. People who had difficulties in thinking or remembering had higher levels of urinary heavy metals, phthalates, pesticides and hydrocarbon concentrations but lower levels of urinary arsenic and polyfluorinated compound concentrations. During the recent past week, 146 people (8.2 %) had trouble remembering for more than three times while 619 people (35.2 %) had that for one to three times. These people had higher levels of urinary heavy metals, phthalates, pesticides and hydrocarbon concentrations but lower levels of urinary polyfluorinated compound concentrations. There were no associations with urinary bisphenols, parabens, perchlorate, nitrate or thiocyanate concentrations. This is the first time observing statistically significant risk associations of urinary heavy metals, phthalates, pesticides and hydrocarbon concentrations and the remembering condition specifically in the elderly, although the causality cannot be established. Elimination of such environmental chemicals in humans might need to be considered in future health policy and intervention programs.
Afficher plus [+] Moins [-]Lewis acid catalysis and Green oxidations: sequential tandem oxidation processes induced by Mn-hyperaccumulating plants Texte intégral
2015
Escande, Vincent | Renard, Brice-Loïc | Grison, Claude
Among the phytotechnologies used for the reclamation of degraded mining sites, phytoextraction aims to diminish the concentration of polluting elements in contaminated soils. However, the biomass resulting from the phytoextraction processes (highly enriched in polluting elements) is too often considered as a problematic waste. The manganese-enriched biomass derived from native Mn-hyperaccumulating plants of New Caledonia was presented here as a valuable source of metallic elements of high interest in chemical catalysis. The preparation of the catalyst Eco-Mn₁and reagent Eco-Mn₂derived from Grevillea exul exul and Grevillea exul rubiginosa was investigated. Their unusual polymetallic compositions allowed to explore new reactivity of low oxidative state of manganese—Mn(II) for Eco-Mn₁and Mn(IV) for Eco-Mn₂. Eco-Mn₁was used as a Lewis acid to catalyze the acetalization/elimination of aldehydes into enol ethers with high yields; a new green and stereoselective synthesis of (−)-isopulegol via the carbonyl-ene cyclization of (+)-citronellal was also performed with Eco-Mn₁. Eco-Mn₂was used as a mild oxidative reagent and controlled the oxidation of aliphatic alcohols into aldehydes with quantitative yields. Oxidative cleavage was interestingly noticed when Eco-Mn₂was used in the presence of a polyol. Eco-Mn₂allowed direct oxidative iodination of ketones without using iodine, which is strongly discouraged by new environmental legislations. Finally, the combination of the properties in the Eco-Mn catalysts and reagents gave them an unprecedented potential to perform sequential tandem oxidation processes through new green syntheses of p-cymene from (−)-isopulegol and (+)-citronellal; and a new green synthesis of functionalized pyridines by in situ oxidation of 1,4-dihydropyridines.
Afficher plus [+] Moins [-]High rates of anaerobic oxidation of methane, ethane and propane coupled to thiosulphate reduction Texte intégral
2015
Suarez-Zuluaga, Diego A. | Weijma, Jan | Timmers, Peer H. A. | Buisman, Cees J. N.
Anaerobic methane oxidation coupled to sulphate reduction and the use of ethane and propane as electron donors by sulphate-reducing bacteria represent new opportunities for the treatment of streams contaminated with sulphur oxyanions. However, growth of microbial sulphate-reducing populations with methane, propane or butane is extremely slow, which hampers research and development of bioprocesses based on these conversions. Thermodynamic calculations indicate that the growth rate with possible alternative terminal electron acceptors such as thiosulphate and elemental sulphur may be higher, which would facilitate future research. Here, we investigate the use of these electron acceptors for oxidation of methane, ethane and propane, with marine sediment as inoculum. Mixed marine sediments originating from Aarhus Bay (Denmark) and Eckernförde Bay (Germany) were cultivated anaerobically at a pH between 7.2 and 7.8 and a temperature of 15 °C in the presence of methane, ethane and propane and various sulphur electron acceptors. The sulphide production rates in the conditions with methane, ethane and propane with sulphate were respectively 2.3, 2.2 and 1.8 μmol S L⁻¹ day⁻¹. For sulphur, no reduction was demonstrated. For thiosulphate, the sulphide production rates were up to 50 times higher compared to those of sulphate, with 86.2, 90.7 and 108.1 μmol S L⁻¹ day⁻¹for methane, ethane and propane respectively. This sulphide production was partly due to disproportionation, 50 % for ethane but only 7 and 14 % for methane and propane respectively. The oxidation of the alkanes in the presence of thiosulphate was confirmed by carbon dioxide production. This is, to our knowledge, the first report of thiosulphate use as electron acceptor with ethane and propane as electron donors. Additionally, these results indicate that thiosulphate is a promising electron acceptor to increase start-up rates for sulphate-reducing bioprocesses coupled to short-chain alkane oxidation.
Afficher plus [+] Moins [-]Mercury in precipitation over the coastal zone of the southern Baltic Sea, Poland Texte intégral
2015
Siudek, Patrycja | Falkowska, Lucyna | Brodecka, Aleksandra | Kowalski, Artur | Frankowski, Marcin | Siepak, Jerzy
An investigation of atmospheric mercury was conducted in the urban coastal zone of the Gulf of Gdansk (Baltic Sea, Poland) in 2008. Rainwater samples were collected in bulk samplers and Hg concentration was determined using AAS method. Total mercury concentration ranged from 1.9 to 14.8 ng l⁻¹(the mean was 8.3 ng l⁻¹with standard deviation ±3.7), out of which about 34 % were water-soluble Hg(II) forms. Distribution of Hg species in rainwater was related to both the emission source and the atmospheric processes. During the sampling period, two maxima of Hg concentration in precipitation were observed: the first in the cold season and the second one in the warm season. Elevated concentrations of Hg in wintertime precipitation were generally the result of local urban atmospheric emission connected with the following anthropogenic sources: intensive combustion of fossil fuels in domestic furnaces, individual power/heat generating plants, and motor vehicles. During summertime, Hg° re-emitted from contaminated land and sea surfaces was photochemically oxidized by active atmospheric substances (e.g., hydroxyl radicals, hydrogen peroxide, halogens) and could be an additional source of atmospherically deposited Hg. The results presented in this work indicate that rainwater Hg concentration and deposition values are not much higher in comparison with other urban locations along the Baltic Sea basin and other coastal cities. However, the elevated mercury concentration in rainwater and, consequently, higher deposition ratio could appear occasionally as an effect of intensive anthropogenic emissions (domestic heating) and/or photochemical reactions.
Afficher plus [+] Moins [-]Nanoparticle pollution and associated increasing potential risks on environment and human health: a case study of China Texte intégral
2015
Gao, Yang | Yang, Tiantian | Jin, Jin
The aims of this study are (1) to discuss the mechanism of nanoparticle lifecycle and estimate the impacts of its associated pollution on environment and human health; and (2) to provide recommendation to policy makers on how to leverage nanopollution and human health along with the rapid development of economics in China. Manufactured nanoparticles (MNPs) could either directly or indirectly impair human health and the environment. Exposures to MNP include many ways, such as via inhalation, ingestion, direct contact, or the use of consumer products over the lifecycle of the product. In China, the number of people exposed to MNP has been increasing year by year. To better provide medical care to people exposed to MNP, the Chinese government has established many disease control and prevention centers over China. However, the existing facilities and resources for controlling MNP are still not enough considering the number of people impacted by MNP and the number of ordinary workers in the MNP related industry applying for their occupational identification through the Center for Disease Control and Prevention. China should assess the apparent risk environment and human health being exposed to MNP and develop action plans to reduce the possibility of direct contacts between human beings and the emerging nanomaterials. In addition, we suggest more comprehensive studies on the MNP behavior and the development of quantitative approaches to measure MNP transport, and persistence should be carried out.
Afficher plus [+] Moins [-]Protective effect of Mn(III)–desferrioxamine B upon oxidative stress caused by ozone and acid rain in the Brazilian soybean cultivar Glycine max “Sambaiba” Texte intégral
2015
Esposito, Jéssica Bordotti Nobre | Espósito, Breno Pannia | Azevedo, Ricardo Antunes | Cruz, Luciano Soares | da Silva, Luzimar Campos | de Souza, Silvia Ribeiro
This study aimed to investigate the effects of the Mn complex (Mn(III)–desferrioxamine B (MnDFB)) on oxidative stress in the Brazilian soybean cultivar Glycine max “Sambaiba” following exposure to ozone and acid rain. We determined the suitable dose of MnDFB to apply to G. max seedlings using a dose–response curve. The highest superoxide dismutase (SOD) activity and Mn content in leaves were found upon the application of 8 μM MnDFB. Thus, G. max seedlings pretreated with 8 μM MnDFB were individually exposed to ozone and acid rain simulated. Pretreatment with MnDFB reduced lipid peroxidation upon ozone exposure and increased SOD activity in leaves; it did not alter the metal content in any part of the plant. Conversely, following acid rain exposure, neither the metal content in leaves nor SOD enzyme activity were directly affected by MnDFB, unlike pH. Our findings demonstrated that exogenous MnDFB application before ozone exposure may modulate the MnSOD, Cu/ZnSOD, and FeSOD activities to combat the ROS excess in the cell. Here, we demonstrated that the applied dose of MnDFB enhances antioxidative defenses in soybean following exposure to acid rain and especially to ozone.
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