Affiner votre recherche
Résultats 1721-1730 de 2,513
Speciation of non-methane hydrocarbons (NMHCs) from anthropogenic sources in Beirut, Lebanon Texte intégral
2014
Salameh, T. | Afif, C. | Sauvage, S. | Borbon, A. | Locoge, N.
The chemical composition of emissions from the different anthropogenic sources of non-methane hydrocarbons (NMHC) is essential for modeling and source apportionment studies. The speciated profiles of major NMHC sources in Lebanon, including road transport, gasoline vapor, power generation, and solvent use were established. Field sampling have been carried out by canisters in 2012. Around 67 NMHC (C2 to C9) were identified and quantified by using a gas chromatograph equipped with a flame ionization detector. Typical features of the roadway emissions included high percentages of isopentane, butane, toluene, xylenes, ethylene, and ethyne. Gasoline evaporation profiles included high percentage of the C4–C5 saturated hydrocarbons reaching 59 %. The main compounds of the power generator emissions are related to combustion. Toluene and C8–C9 aromatics were the most abundant species in emissions from paint applications. Finally, the impact of the use of region-specific source profile is tackled regarding the implication on air quality.
Afficher plus [+] Moins [-]Synthesis and characterization of nanocrystalline TiO2 with application as photoactive coating on stones Texte intégral
2014
Bergamonti, Laura | Alfieri, Ilaria | Franzò, Marco | Lorenzi, Andrea | Montenero, Angelo | Predieri, Giovanni | Raganato, Marina | Calia, Angela | Lazzarini, Laura | Bersani, Danilo | Lottici, Pier Paolo
Self-cleaning photocatalytic coatings for biocalcarenite stones, based on TiO₂nanoparticles obtained by sol–gel processes at different pH values and also adding gold particles, have been investigated. The selected test material is a biocalcarenite named “pietra di Lecce” (Lecce stone), outcropping in Southern Italy. Scanning electron microscopy with energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, and Raman investigations were carried out to characterize the TiO₂nanoparticles and coatings. Nanocrystalline anatase and, to a lesser extent, brookite phases are obtained. Photocatalytic activity of the TiO₂sols and of the coatings on “pietra di Lecce” was assessed under ultraviolet irradiation, monitoring methyl orange (MeO) dye degradation as a function of time. To evaluate the harmlessness of the treatment, colorimetric tests and water absorption by capillarity were performed. The results show good photodegradation rates for titania nanosols, particularly when putting in Au particles, whereas a satisfactory chromatic compatibility between the sol and the surface of the calcarenite is found only without Au addition. HIGHLIGHTS: Sols of nanocrystalline titania at different pH values and with Au particles were prepared and characterized. Satisfactory photodegradation of MeO by the sols in solution and on calcarenite-coated surfaces is obtained. The addition of Au particles improves the photodegradation activity but gives poor chromatic results on “pietra di Lecce”.
Afficher plus [+] Moins [-]Extraction of Sudan dyes from environmental water by hemimicelles-based magnetic titanium dioxide nanoparticles Texte intégral
2014
Li, Chenyu | Chen, Ligang | You, Xiaoxiao
A novel method for the extraction of Sudan dyes including Sudan I, II, III, and IV from environmental water by magnetic titanium dioxide nanoparticles (Fe₃O₄@TiO₂) coated with sodium dodecylsulfate (SDS) as adsorbent was reported. Fe₃O₄@TiO₂ was synthesized by a simple method and was characterized by transmission electron microscopy, Fourier-transform infrared spectrometry, and vibrating sample magnetometer. The magnetic separation was quite efficient for the adsorption and desorption of Sudan dyes. The effect of the amount of SDS, extraction time, pH, desorption condition, maximal extraction volume, and humic acid on the extraction process were investigated. This method was employed to analyze three environmental water samples. The results demonstrated that our proposed method had wide linear range (25–5,000 ng L⁻¹) with a good linearity (R ² > 0.999) and low detection limits (2.9–7.3 ng L⁻¹). An enrichment factor of 1,000 was achieved. In all three spiked levels (25, 250, and 2,500 ng L⁻¹), the recoveries of Sudan dyes were in the range of 86.9–93.6 %. The relative standard deviations obtained were ranging from 2.5 to 9.3 %. That is to say, the new method was fast and effective for the extraction of Sudan dye from environmental water.
Afficher plus [+] Moins [-]Human health risk from organ-specific accumulation of toxic metals and response of antioxidants in edible fish species from Chenab River, Pakistan Texte intégral
2014
Waheed, Sidra | Kamal, Atif | Malik, Riffat Naseem
In the current study, the bioaccumulation of essential and nonessential metals and related antioxidant activity were analyzed in three organs (muscle, gills, and liver) of herbivorous (HF) and carnivorous (CF) edible fish of Chenab River. The comparative analysis revealed a more heterogeneous accumulation of metals in the muscles of HF fish than that of CF fish [chromium (Cr, 3.4 μg g⁻¹), cobalt (Co, 1.7 μg g⁻¹), copper (Cu, 3 μg g⁻¹), and iron (Fe, 45 μg g⁻¹) versus Cr (1.3 μg g⁻¹), Co (0.1 μg g⁻¹), Cu (1.1 μg g⁻¹), and Fe (33 μg g⁻¹), respectively, P < 0.001]. These results implied an organ-specific accumulation of metals at different trophic levels. According to logistic regression analysis, the bioaccumulation of metals had marked differences in HF and CF. The antioxidant activity was significantly related to the tissue type and the metals to which the organs are exposed to. The liver of CF fish had a higher activity of antioxidant superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and lipid peroxidase (LPO) than that of HF (P < 0.05). LPO and guaiacol peroxidase (POD) in both groups were associated with a number of metals, but in HF, cadmium (Cd), Cr, Pb, and Zn were more related with the LPO and SOD activities. Moreover, Cd, Co, Fe, Pb, Ni, Cu, and Zn were above the permissible limits set by various agencies. In numerous cases, our results were even higher than those previously reported in the literature. The results provide an insight into the pollution pattern of Chenab River. These results may be helpful in the future to identify biomarkers of exposure in aquatic organisms.
Afficher plus [+] Moins [-]Development and implementation of surface water quality standards for protection of human health in Korea Texte intégral
2014
An, Youn-Joo | Kwak, Jin II | Nam, Sun-Hwa | Jung, Myung-sook
Current water quality standards for the protection of human health in Korea include 17 substances found in rivers and streams. Due to increasing concern over the release of hazardous chemicals into the aquatic environment, there has been a demand for additional water quality standards. Therefore, the Korean Ministry of the Environment plans to gradually increase the number of water quality standards to 30 substances, including 22 substances for protection of human health and 8 substances for protection of aquatic ecosystems by 2015. In this study, new water quality standards for protection of human health were established for 1,4-dioxane, formaldehyde, and hexachlorobenzene. We selected candidate hazardous chemicals, conducted a human health risk assessment to determine priority chemicals, established water quality standards based on technical analyses and comparison with domestic and developed countries’ water quality standards, and conducted an expert review. Water quality standards for protection of aquatic ecosystems will be derived in the near future. This study describes how the water quality standards for protection of human health were developed and implemented. Current status, recent expansion, and future plans for water quality standards in Korea are also covered.
Afficher plus [+] Moins [-]Characteristics of water-soluble inorganic ions in PM2.5 and PM 2.5–10 in the coastal urban agglomeration along the Western Taiwan Strait Region, China Texte intégral
2014
Yin, Liqian | Niu, Zhenchuan | Chen, Xiaoqiu | Chen, Jinsheng | Zhang, Fuwang | Xu, Lingling
PM₂.₅and PM₂.₅–₁₀aerosol samples were collected in four seasons during November 2010, January, April, and August 2011 at 13 urban/suburban sites and one background site in Western Taiwan Straits Region (WTSR), which is the coastal area with rapid urbanization, high population density, and deteriorating air quality. The 10 days average PM₂.₅concentrations were 92.92, 51.96, 74.48, and 89.69 μg/m³in spring, summer, autumn, and winter, respectively, exceeding the Chinese ambient air quality standard for annual average value of PM₂.₅(grade II, 35 μg/m³). Temporal distribution of water-soluble inorganic ions (WSIIs) in PM₂.₅was coincident with PM₂.₅mass concentrations, showing highest in spring, lowest in summer, and middle in autumn and winter. WSIIs took considerable proportion (42.2∼50.1 %) in PM₂.₅and PM₂.₅–₁₀. Generally, urban/suburban sites had obviously suffered severer pollution of fine particles compared with the background site. The WSIIs concentrations and characteristics were closely related to the local anthropogenic activities and natural environment, urban sites in cities with higher urbanization level, or sites with weaker diffuse condition suffered severer WSIIs pollution. Fossil fuel combustion, traffic emissions, crustal/soil dust, municipal constructions, and sea salt and biomass burnings were the major potential sources of WSIIs in PM₂.₅in WTSR according to the result of principal component analysis.
Afficher plus [+] Moins [-]Survival of Escherichia coli O157:H7 in soils under different land use types Texte intégral
2014
Wang, Haizhen | Zhang, Taoxiang | Wei, Gang | Wu, Laosheng | Wu, Jianjun | Xu, Jianming
Laboratory studies on Escherichia coli O157:H7 survival in soils from four different land use types: forest, tea plantation, bamboo grove, and vegetable garden were investigated at 25 ± 1 °C with the field capacity (soil water content at −33 kPa). Results showed that E. coli O157:H7 declined quickly in the test soils, but its survival dynamics varied in the soils under different land use types. The survival time needed to reach the detection limit (td) in the test soils ranged from 2.1 to 3.6 days, with slightly longer tdvalues being observed in soils from the bamboo grove. Stepwise multiple regression analysis revealed that the tdvalues were shorter in sandy, lower pH, and lower organic carbon content soils. Different E. coli O157:H7 survival time in the soils under different land uses suggests that it is important to adapt proper management practices for reducing the potential risks of pathogen contamination when diary manure is applied to agricultural land.
Afficher plus [+] Moins [-]Contrasting cellular stress responses of Baikalian and Palearctic amphipods upon exposure to humic substances: environmental implications Texte intégral
2014
Protopopova, Marina V. | Pavlichenko, Vasiliy V. | Menzel, Ralph | Putschew, Anke | Luckenbach, Till | Steinberg, Christian E. W.
The species-rich, endemic amphipod fauna of Lake Baikal does not overlap with the common Palearctic fauna; however, the underlying mechanisms for this are poorly understood. Considering that Palearctic lakes have a higher relative input of natural organic compounds with a dominance of humic substances (HSs) than Lake Baikal, we addressed the question whether HSs are candidate factors that affect the different species compositions in these water bodies. We hypothesized that interspecies differences in stress defense might reveal that Baikalian amphipods are inferior to Palearctic amphipods in dealing with HS-mediated stress. In this study, two key mechanisms of general stress response were examined: heat-shock protein 70 (HSP70) and multixenobiotic resistance-associated transporters (ABCB1). The results of quantitative polymerase chain reaction (qPCR) showed that the basal levels (in 3-day acclimated animals) of hsp70 and abcb1 transcripts were lower in Baikalian species (Eulimnogammarus cyaneus, Eulimnogammarus verrucosus, Eulimnogammarus vittatus—the most typical littoral species) than in the Palearctic amphipod (Gammarus lacustris—the only Palearctic species distributed in the Baikalian region). In the amphipods, the stress response was induced using HSs at 10 mg L⁻¹dissolved organic carbon, which was higher than in sampling sites of the studied species, but well within the range (3–10 mg L⁻¹) in the surrounding water bodies populated by G. lacustris. The results of qPCR and western blotting (n = 5) showed that HS exposure led to increased hsp70/abcb1 transcripts and HSP70 protein levels in G. lacustris, whereas these transcript levels remained constant or decreased in the Baikalian species. The decreased level of stress transcripts is probably not able to confer an effective tolerance to Baikalian species against further environmental stressors in conditions with elevated HS levels. Thus, our results suggest a greater robustness of Palearctic amphipods and a higher sensitivity of Baikalian amphipods to HS challenge, which might prevent most endemic species from migrating to habitats outside Lake Baikal.
Afficher plus [+] Moins [-]Chemically coupled microwave and ultrasonic pre-hydrolysis of pulp and paper mill waste-activated sludge: effect on sludge solubilisation and anaerobic digestion Texte intégral
2014
Tyagi, Vinay Kumar | Lo, Shang-Lien | Rajpal, Ankur
The effects of alkali-enhanced microwave (MW; 50–175 °C) and ultrasonic (US) (0.75 W/mL, 15–60 min) pretreatments, on solubilisation and subsequent anaerobic digestion efficiency of pulp and paper mill waste-activated sludge, were investigated. Improvements in total chemical oxygen demand and volatile suspended solids (VSS) solubilisation were limited to 33 and 39 % in MW pretreatment only (175 °C). It reached 78 and 66 % in combined MW–alkali pretreatment (pH 12 + 175 °C), respectively. Similarly, chemical oxygen demand and VSS solubilisation were 58 and 37 % in US pretreatment alone (60 min) and it improved by 66 and 49 % after US–alkali pretreatment (pH 12 + 60 min), respectively. The biogas yield for US 60 min–alkali (pH 12)-pretreated sludge was significantly improved by 47 and 20 % over the control and US 60 reactors, respectively. The biogas generation for MW (150 °C)–alkali (pH 12)-pretreated sludge was only 6.3 % higher than control; however, it was 8.3 % lower than the MW (150 °C) reactor, which was due to the inhibition of anaerobic activity under harsh thermal–alkali treatment condition.
Afficher plus [+] Moins [-]The GMOS cyber(e)-infrastructure: advanced services for supporting science and policy Texte intégral
2014
Cinnirella, S. | D’Amore, F. | Bencardino, M. | Sprovieri, F. | Pirrone, N.
The need for coordinated, systematized and catalogued databases on mercury in the environment is of paramount importance as improved information can help the assessment of the effectiveness of measures established to phase out and ban mercury. Long-term monitoring sites have been established in a number of regions and countries for the measurement of mercury in ambient air and wet deposition. Long term measurements of mercury concentration in biota also produced a huge amount of information, but such initiatives are far from being within a global, systematic and interoperable approach. To address these weaknesses the on-going Global Mercury Observation System (GMOS) project ( www.gmos.eu ) established a coordinated global observation system for mercury as well it retrieved historical data ( www.gmos.eu/sdi ). To manage such large amount of information a technological infrastructure was planned. This high-performance back-end resource associated with sophisticated client applications enables data storage, computing services, telecommunications networks and all services necessary to support the activity. This paper reports the architecture definition of the GMOS Cyber(e)-Infrastructure and the services developed to support science and policy, including the United Nation Environmental Program. It finally describes new possibilities in data analysis and data management through client applications.
Afficher plus [+] Moins [-]