خيارات البحث
النتائج 3221 - 3230 من 4,043
Monitoring an outdoor smoking area by means of PM2.5 measurement and vegetal biomonitoring النص الكامل
2016
da Silveira Fleck, Alan | Carneiro, Maria Fernanda Hornos | Barbosa, Fernando Jr | Thiesen, Flavia Valladão | Amantea, Sergio Luis | Rhoden, Claudia Ramos
The extension of pollutant accumulation in plant leaves associated with its genotoxicity is a common approach to predict the quality of outdoor environments. However, this approach has not been used to evaluate the environmental quality of outdoor smoking areas. This study aims to evaluate the effects of environmental tobacco smoke (ETS) by assessing particulate matter 2.5 μm (PM₂.₅) levels, the pollen abortion assay, and trace elements accumulated in plant leaves in an outdoor smoking area of a hospital. For this, PM₂.₅ was measured by active monitoring with a real time aerosol monitor for 10 days. Eugenia uniflora trees were used for pollen abortion and accumulated element assays. Accumulated elements were also assessed in Tradescantia pallida leaves. The median concentration of PM₂.₅ in the smoking area in all days of monitoring was 66 versus 34 μg/m³ in the control area (P < 0.001). In addition, the elements Al, Cd, Cu, Ni, Pb, Rb, Sb, Se, and V in Tradescantia pallida and Al, Ba, Cr, Cu, Fe, Mg, Pb, and Zn in Eugenia uniflora were in higher concentration in the smoking area when compared to control area. Smoking area also showed higher rate of aborted grains (26.1 ± 10.7 %) compared with control (17.6 ± 4.5 %) (P = 0.003). Under the study conditions, vegetal biomonitoring proved to be an effective tool for assessing ETS exposure in outdoor areas. Therefore, vegetal biomonitoring of ETS could be a complement to conventional analyses and also proved to be a cheap and easy-handling tool to assess the risk of ETS exposure in outdoor areas.
اظهر المزيد [+] اقل [-]Trace elements deposition in the Tierra del Fuego region (south Patagonia) by using lichen transplants after the Puyehue-Cordón Caulle (north Patagonia) volcanic eruption in 2011 النص الكامل
2016
Conti, M. E. | Jasan, Raquel | Finoia, Maria Grazia | Iavicoli, Ivo | Plá, Rita
Lichen Usnea barbata transplants were tested as a biomonitor of atmospheric deposition in an apparently pristine environment that is Tierra del Fuego region (Patagonia, Argentina). The present survey is connected with the volcanic eruption that started in north Patagonia on June 4, 2011 from the Puyehue-Cordón Caulle volcano, Chile (north Patagonia, at 1700 km of distance of our sampling sites). Lichens were collected in September 2011 (one month of exposure) and September 2012 (1 year of exposure) in 27 sites covering the northern region of the province where trees are not present. The atmospheric deposition of 27 elements by using Neutron Activation Analysis (NAA) was determined in the collected samples. The first aim of the study was to evaluate the influence of the volcanic eruption on the regional atmospheric deposition comparing our results with baseline data we determined in U. barbata in 2006 in the same sites. The second aim was to test possible patterns of bioaccumulation between the two sampling campaigns after the volcanic eruption. With respect to 2006 baseline levels, we found significant higher levels for As, Ba, Co, Cr, Cs, Na, Sb and U in lichens collected after 1 month of exposure (first sampling campaign—2011). Between the two sampling campaigns (2011–2012) after the eruption, lichens reflected the natural contamination by volcanic ashes with significantly higher median levels of Br, Cr, Fe, K, Na, Sc, and Se. Results confirmed the very good aptitude of U. barbata to reflect the levels of elements in the environment at global scale and to reflect the volcanic emissions at distant places. Volcanic eruptions cause the emission in the atmosphere of elevated levels of particulate matter. In this regard, our findings demonstrate the importance to evaluate the metal composition of the particles to avoid possible health effects.
اظهر المزيد [+] اقل [-]Measurements of VOC/SVOC emission factors from burning incenses in an environmental test chamber: influence of temperature, relative humidity, and air exchange rate النص الكامل
2016
Manoukian, A. | Buiron, D. | Temime-Roussel, B. | Wortham, H. | Quivet, E.
This study investigates the influence of three environmental indoor parameters (i.e., temperature, relative humidity, and air exchange rate) on the emission of 13 volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) during incense burning. Experiments have been carried out using an environmental test chamber. Statistical results from a classical two-level full factorial design highlight the predominant effect of ventilation on emission factors. The higher the ventilation, the higher the emission factor. Moreover, thanks to these results, an estimation of the concentration range for the compounds under study can be calculated and allows a quick look of indoor pollution induced by incense combustion. Carcinogenic substances (i.e., benzene, benzo(a)pyrene, and formaldehyde) produced from the incense combustion would be predicted in typical living indoors conditions to reach instantaneous concentration levels close to or higher than air quality exposure threshold values.
اظهر المزيد [+] اقل [-]Elimination of radiocontrast agent diatrizoic acid by photo-Fenton process and enhanced treatment by coupling with electro-Fenton process النص الكامل
2016
Bocos, Elvira | Oturan, Nihal | Pazos, Marta | Sanromán, Maria Ángeles | Oturan, Mehmet A.
The removal of radiocontrast agent diatrizoic acid (DIA) from water was performed using photo-Fenton (PF) process. First, the effect of H₂O₂ dosage on mineralization efficiency was determined using ultraviolet (UV) irradiation. The system reached a maximum mineralization degree of 60 % total organic carbon (TOC) removal at 4 h with 20 mM initial H₂O₂ concentration while further concentration values led to a decrease in TOC abatement efficiency. Then, the effect of different concentrations of Fenton’s reagents was studied for homogeneous Fenton process. Obtained results revealed that 0.25 mM Fe³⁺ and 20 mM H₂O₂ were the best conditions, achieving 80 % TOC removal efficiency at 4 h treatment. Furthermore, heterogeneous PF treatment was developed using iron-activated carbon as catalyst. It was demonstrated that this catalyst is a promising option, reaching 67 % of TOC removal within 4 h treatment without formation of iron leachate in the medium. In addition, two strategies of enhancement for process efficiency are proposed: coupling of PF with electro-Fenton (EF) process in two ways: photoelectro-Fenton (PEF) or PF followed by EF (PF-EF) treatments, achieving in both cases the complete mineralization of DIA solution within only 2 h. Finally, the Microtox tests revealed the formation of more toxic compounds than the initial DIA during PF process, while, it was possible to reach total mineralization by both proposed alternatives (PEF or PF-EF) and thus to remove the toxicity of DIA solution.
اظهر المزيد [+] اقل [-]Degradation of carbamazepine by UV/chlorine advanced oxidation process and formation of disinfection by-products النص الكامل
2016
Zhou, Shiqing | Xia, Ying | Li, Ting | Yao, Tian | Shi, Zhou | Zhu, Shumin | Gao, Naiyun
Pharmaceuticals in water are commonly found and are not efficiently removed by current treatment processes. Degradation of antiepileptic drug carbamazepine (CBZ) by UV/chlorine advanced oxidation process was systematically investigated in this study. The results showed that the UV/chlorine process was more effective at degrading CBZ than either UV or chlorination alone. The CBZ degradation followed pseudo-first order reaction kinetics, and the degradation rate constants (kₒbₛ) were affected by the chlorine dose, solution pH, and natural organic matter concentration to different degrees. Degradation of CBZ greatly increased with increasing chlorine dose and decreasing solution pH during the UV/chlorine process. Additionally, the presence of natural organic matter in the solution inhibited the degradation of CBZ. UV photolysis, chlorination, and reactive species (hydroxyl radical •OH and chlorine atoms •Cl) were identified as responsible for CBZ degradation in the UV/chlorine process. Finally, a degradation pathway for CBZ in the UV/chlorine process was proposed and the formation potentials of carbonaceous and nitrogenous disinfection by-products were evaluated. Enhanced formation of trichloroacetic acid, dichloroacetonitrile, and trichloronitromethane precursors should be considered when applying UV/chlorine advanced oxidation process to drinking water.
اظهر المزيد [+] اقل [-]Aqueous photodegradation of antibiotic florfenicol: kinetics and degradation pathway studies النص الكامل
2016
Zhang, Ya | Li, Jianhua | Zhou, Lei | Wang, Guoqing | Feng, Yanhong | Wang, Zunyao | Yang, Xi
The occurrence of antibacterial agents in natural environment was of scientific concern in recent years. As endocrine disrupting chemicals, they had potential risk on ecology system and human beings. In the present study, the photodegradation kinetics and pathways of florfenicol were investigated under solar and xenon lamp irradiation in aquatic systems. Direct photolysis half-lives of florfenicol were determined as 187.29 h under solar irradiation and 22.43 h under xenon lamp irradiation, respectively. Reactive oxygen species (ROS), such as hydroxyl radical (·OH) and singlet oxygen (¹O₂) were found to play an important role in indirect photolysis process. The presence of nitrate and dissolved organic matters (DOMs) could affect photolysis of florfenicol in solutions through light screening effect, quenching effect, and photoinduced oxidization process. Photoproducts of florfenicol in DOMs solutions were identified by solid phase extraction-liquid chromatography-mass spectrometry (SPE-LC-MS) analysis techniques, and degradation pathways were proposed, including photoinduced hydrolysis, oxidation by ¹O₂ and ·OH, dechlorination, and cleavage of the side chain.
اظهر المزيد [+] اقل [-]Crocin protects human embryonic kidney cells (HEK293) from α- and β-Zearalenol-induced ER stress and apoptosis النص الكامل
2016
Ben Salem, Intidhar | Boussabbeh, Manel | Prola, Alexandre | Guilbert, Arnaud | Bacha, Hassen | Lemaire, Christophe | Abid-Essefi, Salwa
α-zearalenol (α-ZOL) and β-zearalenol (β-ZOL) are the major metabolites of Zearalenone (ZEN) and are known to induce many toxic effects. In the present study, we investigated the involvement of endoplasmic reticulum (ER) stress in α- and β-ZOL-mediated toxicity in human kidney cells (HEK293) and evaluated the effect of a common dietary compound Crocin (CRO), from saffron. We show that α- and β-ZOL treatment induces ER stress as evidenced by the upregulation of the 78 kDa glucose-regulated protein (GRP78) and the Growth arrest and DNA damage-inducible protein (GADD34). Activation of the ER stress response is associated with activation of the mitochondrial pathway of apoptosis. This apoptotic process is characterized by an increase in ROS generation and lipid peroxidation, a loss of mitochondrial transmembrane potential (ΔΨm) and activation of caspases. We also demonstrate that the antioxidant properties of CRO help to prevent ER stress and reduce α- and β-ZOL-induced apoptosis in HEK293 cells. Our results suggest that saffron consumption might be helpful to prevent α- and β-ZOL-induced ER stress and toxicity.
اظهر المزيد [+] اقل [-]Toxicity of 3,5,6-trichloro-2-pyridinol tested at multiple stages of zebrafish (Danio rerio) development النص الكامل
2016
Suvarchala, Gonuguntla | Philip, Gundala Harold
Organophosphate compounds (OP) are widely used throughout the world for pest control. 3,5,6-Trichloro-2-pyridinol (TCP) is a primary metabolite of two OP compounds namely CP and triclopyr. This study is carried out to know whether a metabolite of parent compound is doing well or harm to biota. The potential effect of TCP was evaluated on development as destabilization of any events transpiring during embryogenesis could be deleterious. To determine this, 4-hpf zebrafish embryos were exposed to five concentrations of TCP (200, 400, 600, 800, 1000 μg/L) or 99.5 % acetone (solvent control). Different early life-stage parameters were observed at four different developmental stages, 24, 48, 72 and 96 hpf. TCP-treated embryo/larvae showed increased mortality, delay in hatching time and decrease in percentage of hatched embryos. Reduction in heartbeat rate, blood flow and body and eye pigmentation was noticed in a dose-dependent manner. Pericardial and yolk sac edema were most severe malformations caused by TCP. Along with this crooked spine/notochord, tail deformation was noticed in hatched and unhatched embryos. The malformations observed provide a good starting point for examination of the molecular mechanisms that are affected during development by TCP. Results gain significance as TCP, which is a breakdown product, appears to be more toxic during development compared to parent compound, CP (our earlier publication).
اظهر المزيد [+] اقل [-]Polybrominated diphenyl ethers (PBDEs) and heavy metals in road dusts from a plastic waste recycling area in north China: implications for human health النص الكامل
2016
Tang, Zhenwu | Huang, Qifei | Yang, Yufei | Nie, Zhiqiang | Cheng, Jiali | Yang, Jun | Wang, Yuwen | Chai, Miao
Road dusts were collected from an area where intense mechanical recycling of plastic wastes occurs in Wen’an, north China. These dusts were investigated for polybrominated diphenyl ethers (PBDEs) and heavy metals contamination to assess the health risk related to these components. Decabromodiphenyl ether (BDE-209) and Σ₂₁PBDE concentrations in these dusts ranged from 2.67 to 10,424 ng g⁻¹ and from 3.23 to 10,640 ng g⁻¹, respectively. These PBDE concentrations were comparable to those observed in road dust from e-waste recycling areas but were 1–2 orders of magnitude higher than concentrations in outdoor or road dusts from other areas. This indicates that road dusts in the study area have high levels of PBDE pollution. BDE-209 was the predominant congener, accounting for 86.3 % of the total PBDE content in dusts. Thus, commercial deca-BDE products were the dominant source. The average concentrations of As, Cd, Cr, Cu, Hg, Pb, Sb, and Zn in these same dust samples were 10.1, 0.495, 112, 54.7, 0.150, 71.8, 10.6, and 186 mg kg⁻¹, respectively. The geoaccumulation index suggests that road dusts in this area are moderately to heavily polluted with Cd, Hg, and Sb. This study shows that plastic waste processing is a major source of toxic pollutants in road dusts in this area. Although the health risk from exposure to dust PBDEs was low, levels of some heavy metals in this dust exceeded acceptable risk levels for children and are of great concern.
اظهر المزيد [+] اقل [-]Degradation of quinolone antibiotic, norfloxacin, in aqueous solution using gamma-ray irradiation النص الكامل
2016
Sayed, Murtaza | Khan, Javed Ali | Shah, Luqman Ali | Shah, Noor S. | Khan, Hasan M. | Rehman, Faiza | Khāna, Ābadura Rahamāna | Khan, Asad M.
This study reports the efficiency of gamma-ray irradiation to degrade quinolone antibiotic, norfloxacin, in aqueous solution. Laboratory batch experiments were conducted to determine the “pseudo-first” order degradation kinetics of norfloxacin in the concentration ranges of 3.4–16.1 mg L⁻¹ by gamma-ray irradiation. The dose constant was found to be dependent on the initial concentration of norfloxacin and gamma-ray irradiation dose rate (D ᵣ). The saturation of norfloxacin sample solutions with N₂, air or N₂O, and the presence of tert-butanol and 2-propanol showed that •OH played more crucial role in the degradation of norfloxacin. The second order rate constants of •OH, eₐq ⁻, and •H with norfloxacin were calculated to be 8.81 × 10⁹, 9.54 × 10⁸, and 1.10 × 10⁹ M⁻¹ s⁻¹, respectively. The effects of various additives including CO₃ ²⁻, HCO₃ ⁻, NO₃ ⁻, NO₂ ⁻, and thiourea and the pH of the medium on the degradation of norfloxacin were also investigated. Norfloxacin degradation was lower in surface water and wastewater than in ultrapure water. Several degradation byproducts of norfloxacin were identified from which the possible degradation pathway was proposed.
اظهر المزيد [+] اقل [-]