خيارات البحث
النتائج 2511 - 2520 من 4,938
An effective treatment method for shale gas drilling cuttings solidified body النص الكامل
2019
Liu, Dong-sheng | Wang, Chao-qiang | Mei, Xu-dong | Qian-Huang, | Ding, Shi-min
The exploration and production of shale gas technology provides a way for utilization of clean fuels. However, during the exploration process of shale gas, enormous amount of drilling cutting was generated and had to be solidified and landfilled. So the accumulation of shale gas drilling cutting solidified body (SGDS)causes severe land resource misuse and environmental complications. This study focuses on the utilization of SGDS as a raw material for the production of cement clinker, and the phase composition, microstructure, and environmental performance of the cement clinker was investigated by X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), energy-dispersive X-ray spectrum analysis (EDX), and soaking test, respectively. The results show that the cement clinker obtained mainly constitutes of typical Portland cement mineral (C₃S, C₂S, C₃A, and C₄AF). The leaching test indicated that the concentration of heavy metal ions in leachate is within the limits allowed by the state “Technical specification for co-processing of solid wastes in cement kiln” (GB 30760-2014). This study therefore provides a benchmark on environmental effects resulting from drilling cuttings and utilization of resources.
اظهر المزيد [+] اقل [-]Performance of Bi2O3/TiO2 prepared by sol-gel on p-Cresol degradation under solar and visible light النص الكامل
2019
Vigil-Castillo, Héctor H. | Hernández-Ramírez, Aracely | Guzmán-Mar, Jorge L. | Ramos-Delgado, Norma A. | Villanueva-Rodríguez, Minerva
Photocatalytic degradation of p-Cresol was evaluated using the mixed oxide Bi₂O₃/TiO₂ (containing 2 and 20% wt. Bi₂O₃ referred as TB2 and TB20) and was compared with bare TiO₂ under simulated solar radiation. Materials were prepared by the classic sol-gel method. All solids exhibited the anatase phase by X-ray diffraction (XRD) and Raman spectroscopy. The synthesized materials presented lower crystallite size and Eg value, and also higher surface area as Bi₂O₃ amount was increased. Bi content was quantified showing near to 70% of theoretical values in TB2 and TB20. Bi₂O₃ incorporation also was demonstrated by X-ray photoelectron spectroscopy (XPS). Characterization of mixed oxides suggests a homogeneous distribution of Bi₂O₃ on TiO₂ surface. Photocatalytic tests were carried out using a catalyst loading of 1 g L⁻¹ under simulated solar light and visible light. The incorporation of Bi₂O₃ in TiO₂ improved the photocatalytic properties of the synthesized materials obtaining better results with TB20 than the unmodified TiO₂ under both radiation sources.
اظهر المزيد [+] اقل [-]Effluent from Citrus Industry: Toxic Parameters of Orange Vinasse النص الكامل
2019
Garcia, Camila Fernandes H. | de Souza, Raphael B. | de Souza, Cleiton Pereira | Fontanetti, Carmem Silvia
Brazil is one of the greatest producers of orange and its orange juice processing industry produces large volumes of solid and liquid waste daily. As an efficient use of the residues from citrus industry, production of bioethanol is highlighted. However, the generation of bioethanol produces a liquid effluent as a by-product, known as vinasse. The objective of this study was to evaluate the toxicity of an effluent from citrus industries, orange vinasse, when applied to soil using Allium cepa seeds. The evaluation was performed by means of germination, root growth, and genotoxic and mutagenic parameters. The EC₅₀ (effectiveness concentration) and ½ EC₅₀, defined in the germination test, were used for genotoxicity tests. Toxicity was observed in dilutions above 40%, which was responsible for reducing the germination speed index. Genotoxicity was observed only using the EC₅₀ and mutagenicity was not detected. According to the results, orange vinasse showed toxicity similar to the sugar cane vinasse, so caution is suggested in the disposal of this effluent into the environment.
اظهر المزيد [+] اقل [-]Estimation of real-world traffic emissions for CO, SO2, and NO2 through measurements in urban tunnels in Tehran, Iran النص الكامل
2019
Heydarizadeh, Ali | Kahforoushan, Davood
Mobile sources are considered to be one of the most important sources of air pollution among which are motor vehicles, recognized as the major contributor of air pollutants in urban areas. To determine the emissions for CO, SO₂, and NO₂ from motor vehicles as part of the attempt to realize the extent of traffic air pollution, measurements were carried out in two heavily traversed traffic tunnels in Tehran metropolitan area. The concentrations of pollutants and metrological and traffic data were collected through intensive measurements from September 27 to October 17, 2016. Resalat Tunnel fleet was composed of about 10% diesel-fueled vehicles and 90% non-diesel-fueled vehicles while throughout the entire duration of our campaign, only non-diesel-fueled vehicles traversed Niayesh Tunnel. Under an average traffic speed of 43 km h⁻¹, emission factors from Resalat Tunnel campaign were measured to be (6.59 ± 2.69)E+3, (1.42 ± 0.84)E+2, and 6.80 ± 4.99 mg km⁻¹ for CO, SO₂, and NO₂, respectively. These values were respectively 11% higher, 22% lower, and 40% higher than those from Niayesh Tunnel measurements which were recorded at a traffic speed of 30 km h⁻¹. Current results indicate that the vehicular emissions in certain countries, especially the developing ones and in this case, Iran, are quite different from those measured in developed countries and that the high emission levels of SO₂ in Iran are associated with the high sulfur content of the gasoline.
اظهر المزيد [+] اقل [-]Analysis of the total factor energy efficiency and its influencing factors of the Belt and Road key regions in China النص الكامل
2019
Yang, Zhongshan | Wei, Xiaoxue
Energy cooperation has been emphasized strongly in the Belt and Road (B&R) initiative. Therefore, the energy efficiency of China has attracted much attention from experts. However, relevant studies are still insufficient. This paper analyzes the total factor energy efficiency (TFEE) and its influencing factors of 17 B&R key regions from 2005 to 2015. We use the ratio of target energy input and actual energy input to calculate the regional TFEE under environmental constraints. The Malmquist index and the Tobit model are applied to investigate the internal and external influences of TFEE. Measurement analysis shows that the TFEE of the B&R key regions has not improved in recent years and it is unbalanced during the study period. Regions in the east area have the highest TFEE; regions in the west area have the second high TFEE; and regions in the north area have the lowest TFEE. Regression analysis shows that for the B&R key regions, technical changes, coal consumption, research and development, and environmental pollution have mainly negative effects on TFEE; pure efficiency changes, scale efficiency changes, economic structure, opening up, and government finance have mainly positive effects on TFEE. Finally, precise policy implications are proposed.
اظهر المزيد [+] اقل [-]How to preserve and handle fish liver samples to conserve RNA integrity النص الكامل
2019
Vehniäinen, Eeva-Riikka | Ruusunen, Maiju | Vuorinen, Pekka J. | Keinänen, Marja | Oikari, Aimo O. J. | Kukkonen, Jussi V. K.
As transcriptomic studies are becoming more and more common, it is important to ensure that the RNA used in the analyses is of good quality. The RNA integrity may be compromised by storage temperature or freeze-thaw cycles, but these have not been well studied in poikilothermic fishes. This work studied the effects of tissue storage time and temperature, and freeze-thaw cycles of tissue and extracted RNA on RNA integrity in brown trout (Salmo trutta L.) liver. The storage time and temperature had an effect on RNA integrity, but RNA suitable for quantitative reverse transcription PCR (RT-qPCR) (RIN > 7) was still obtained from samples preserved at − 20 °C for 6 months. Freeze-thaw cycles of tissue or RNA did not compromise the integrity of RNA. RNA degradation had an effect on RT-qPCR results, and the effect depended on gene. The RT-qPCR analysis of historical samples from a bleached kraft pulp mill effluent exposure in 1984 revealed no significant cyp1a induction. Recommendations are given for the preservation and handling procedures of samples designated for transcriptomic analyses.
اظهر المزيد [+] اقل [-]Bioaccumulation of Heavy Metals (Pb, Cd, Cr, Cu) in Fine Roots Under Three Species of Alders (Alnus spp.) Plantation at Different Soil Substrates Addition on the Reclaimed Combustion Wastes Landfill النص الكامل
2019
Świątek, Bartłomiej | Woś, Bartłomiej | Gruba, Piotr | Pietrzykowski, Marcin
In the study, we have analysed the impact of lead (Pb), cadmium (Cd), chromium (Cr) and copper (Cu) on fine root biomass and the associated level of bioacumulation heavy metals in fine roots under alder plantings (Alnus incana, A. glutinosa and A. viridis) growing on technosols developed from combustion wastes and extremely poor quaternary sands excavated by sand mining. The control sites were located in natural habitats in the Bieszczady Mountains within the natural range of the occurrence of the investigated alder species. Results showed that the bioaccumulation index of heavy metals in the alder roots depended on technosol properties, in particular, pH and texture, and, to a lesser extent, on the total content of heavy metals in soil. Additionally, it was found that in some concentration ranges, Pb and Cr had a stimulating effect on the growth of fine roots.
اظهر المزيد [+] اقل [-]Influence of electronic cigarette vaping on the composition of indoor organic pollutants, particles, and exhaled breath of bystanders النص الكامل
2019
van Drooge, Barend L. | Marco, Esther | Perez, Noemi | Grimalt, Joan O.
The changes of particles and organic pollutants in indoor atmospheres as consequence of vaping with electronic cigarettes have been analyzed. Changes in the composition of volatile organic compounds (VOCs) in exhaled breath of non-smoking volunteers present in the vaping environments have also been studied. The exposure experiments involved non-vaping (n = 5) and vaping (n = 5) volunteers staying 12 h together in a room (54 m²) without external ventilation. The same experiment was repeated without vaping for comparison. Changes in the distributions of particles in the 8–400 nm range were observed, involving losses of nucleation-mode particles (below 20 nm) and increases of coagulation processes leading to larger size particles. In quantitative terms, vaping involved doubling the indoor concentrations of particles smaller than 10 μm, 5 μm, and 1 μm observed during no vaping. The increase of particle mass concentrations was probably produced from bulk ingredients of the e-liquid exhaled by the e-cigarette users. Black carbon concentrations in the indoor and outdoor air were similar in the presence and absence of electronic cigarette emissions. Changes in the qualitative composition of PAHs were observed when comparing vaping and non-vaping days. The nicotine concentrations were examined separately in the gas and in the particulate phases showing that most of the differences between both days were recorded in the former. The particulate phase should therefore be included in nicotine monitoring during vaping (and smoking). The concentration increases of nicotine and formaldehyde were small when compared with those described in other studies of indoor atmospheres or health regulatory thresholds. No significant changes were observed when comparing the concentrations of exhaled breath in vaping and no vaping days. Even the exhaled breath nicotine concentrations in both conditions were similar. As expected, toluene, xylenes, benzene, ethylbenzene, and naphthalene did not show increases in the vaping days since combustion was not involved.
اظهر المزيد [+] اقل [-]Identification of 3-(trifluoromethyl)phenol as the malodorous compound in a pollution incident in the water supply in Catalonia (N.E. Spain) النص الكامل
2019
Quintana, Jordi | Hernández, Alejandra | Ventura, Francesc | Devesa, Ricard | Boleda, Maria Rosa
A study of organic compounds that caused a serious taste and odor episode of water supply in two residential areas in Catalonia (N.E. Spain) was carried out. Sweet and paint/solvent odor were the main descriptors used by consumers. Some cases of sickness and nausea were also associated with drinking water consumption by the consumers. Closed-loop stripping analysis (CLSA) combined with sensory gas chromatography and gas chromatography mass spectrometry detection were used to study the problem. As a result, 3-(trifluoromethyl)phenol (CAS number 98-17-9) was for the first time identified as a responsible of an odor incident in drinking water. Concentration levels of this compound were up to 17,000 ng/L in groundwater and up to 600 ng/L in distributed water. Odor threshold in water for 3-(trifluoromethyl)phenol was determined as 13 ng/L (45 °C).
اظهر المزيد [+] اقل [-]Mercury Concentration in Technosols and Alder Tissue from a Plantation on a Combustion Waste Disposal Site النص الكامل
2019
Woś, Bartłomiej | Sroka, Katarzyna | Józefowska, Agnieszka | Pietrzykowski, Marcin
Combustion of fossil fuels including coal is one of the sources of mercury pollution. Combustion waste from fly ash disposal sites poses a problem for the environment and constitutes a potential source of Hg, thus phytostabilisation is a crucial goal in the mitigation of fossil fuel impact. The paper presents mercury (Hg) concentration in technosols from combustion waste and in individual biomass components (fine roots, bark, stem wood and leaves) of alder species (black, gray and green alder) introduced as part of a long-term experiment to develop a method of phytostabilisation and afforestation of a lignite combustion disposal site. Mercury content in the combustion waste was elevated compared to the data for natural soils from uncontaminated forest areas, however, it did not exceed the amounts considered to be toxic. Hg content in technosols was related to clay and silt fraction content and phosphorus content. Mercury in the alder biomass accumulated mainly in the underground part, especially in the fine roots and displayed a positive correlation with acid and alkaline phosphatase and sulfur content, with no differences in the accumulation of Hg between the alder species. The obtained results indicate that the fine roots are the frontier of Hg biosorption in developed alder systems on combustion waste disposal sites.
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