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351.
Porous media grain size distribution and hydrodynamic forces effects on transport and deposition of suspended particles 总被引:1,自引:0,他引:1
Nasre-Dine Ahfir Ahmed Hammadi Abdellah Alem HuaQing Wang Gilbert Le Bras Tariq Ouahbi 《环境科学学报(英文版)》2017,29(3):161-172
The effects of porous media grain size distribution on the transport and deposition of polydisperse suspended particles under different flow velocities were investigated. Selected Kaolinite particles(2–30 μm) and Fluorescein(dissolved tracer) were injected in the porous media by step input injection technique. Three sands filled columns were used: Fine sand,Coarse sand, and a third sand(Mixture) obtained by mixing the two last sands in equal weight proportion. The porous media performance on the particle removal was evaluated by analysing particles breakthrough curves, hydro-dispersive parameters determined using the analytical solution of convection–dispersion equation with a first order deposition kinetics, particles deposition profiles, and particle-size distribution of the recovered and the deposited particles. The deposition kinetics and the longitudinal hydrodynamic dispersion coefficients are controlled by the porous media grain size distribution. Mixture sand is more dispersive than Fine and Coarse sands. More the uniformity coefficient of the porous medium is large, higher is the filtration efficiency. At low velocities, porous media capture all sizes of suspended particles injected with larger ones mainly captured at the entrance.A high flow velocity carries the particles deeper into the porous media, producing more gradual changes in the deposition profile. The median diameter of the deposited particles at different depth increases with flow velocity. The large grain size distribution leads to build narrow pores enhancing the deposition of the particles by straining. 相似文献
352.
Hazem Hamza Mats Leifels Michael Wilhelm Ibrahim Ahmed Hamza 《Food and environmental virology》2017,9(3):304-313
Human bocavirus (HBoV) is predominantly found in the respiratory tract infections and in the stool of patients with gastroenteritis symptoms. However, data on the prevalence of HBoV genotypes in environmental samples are limited. Here we addressed the prevalence of HBoV in sewage collected from three different wastewater treatment plants in Egypt. HBoV-1, HBoV-2, and HBoV-3 were detected, whereas none of the samples were positive for HBoV-4. The median concentration of HBoV in influent samples was 8.5 × 103 GC/l for HBoV-1, 3.0 × 104 GC/l for HBoV-2, and 2.5 × 104 GC/l for HBoV-3. The concentration was reduced but not completely removed in the effluent samples. The median concentration in the outlet samples was 2.9 × 103 GC/l for HBoV-1, 4.1 × 103 GC/l for HBoV-2, and 2.1 × 103 GC/l for HBoV-3. Moreover, no seasonality pattern of HBoVs was found. The high incidence of HBoV in sewage samples provided an evidence of its circulation in the local population. Although the role of HBoV in respiratory or gastro-intestinal infections still remains to be fully elucidated, the risk of infection via contaminated water should be taken into consideration. 相似文献
353.
On the heating environment in street canyon 总被引:1,自引:1,他引:0
This study investigates the impact of building aspect ratio (building-height-to-street-canyon-width-ratio), wind speed and
surface and air-temperature difference (Δθs−a) on the heating environment within street canyon. The Reynolds-averaged Navier-Stokes (RANS) and energy transport equations
were solved with Renormalization group (RNG) theory version of k-e{\varepsilon} turbulence model. The validation process demonstrated that the model could be trusted for simulating air-temperature and
velocity trends. The temperature and velocity patterns were discussed in idealized street canyons of different aspect ratios
(0.5–2.0) with varying ambient wind speeds (0.5–1.5 m/s) and Δθs−a (2–8 K). Results show that air-temperatures are directly proportional to bulk Richardson number (R
b
) for all but ground heating situation. Conversely, air-temperatures increase significantly across the street canyon with
a decrease in ambient wind speed; however, the impact of Δθs−a was negligible. Clearly, ambient wind speed decreases significantly as it passes over higher AR street canyons. Notably,
air-temperatures were the highest when the windward wall was heated and the least during ground heating. Conversely, air-temperatures
were lower along the windward side but higher within the street canyon when the windward wall was heated. 相似文献
354.
Faruque Ahmed M. Hawa Bibi Takehiko Fukushima Koji Seto Hiroaki Ishiga 《Environmental monitoring and assessment》2011,173(1-4):167-180
A geochemical study of the bottom sediments of Lake Shinji and the River Ohashi in southwestern Japan was carried out to determine their elemental compositions and to evaluate the pollution status of lake sediments by employing enrichment factor (EF), pollution load index (PLI), and geoaccumulation index (I geo). Present-day water quality was also assessed. Results showed that the water quality of Lake Shinji contrasts slightly between the upper and lower parts. The chemical composition of the sediments, as measured by X-ray fluorescence, included major and trace elements and total sulfur (TS). Average abundances of As, Pb, Zn, Cu, Ni, and Cr in the Shinji sediments were 10, 29, 143, 27, 19, and 54 ppm, respectively, compared to 6, 18, 57, 16, 10, and 37 ppm in the river sediments. Based on the EF, PLI, and I geo, the lake sediments are moderately to strongly polluted with respect to As, moderately polluted with Pb, Zn, and Cr, and unpolluted with Cu and Ni. The high EF and I geo for As, Pb, and Zn in the lake sediments indicate that metal concentration has occurred in Shinji. Increases in the abundances of these metals are likely related to the fine-grained nature of the sediments, reducing conditions of the bottom sediments, enrichment in organic matter, and possibly a minor contribution from non-point anthropogenic sources. Trace metal contents are strongly correlated with Fe2O3 and TS, suggesting that Fe oxides and sulfides play a role in controlling abundances in the investigated areas. 相似文献
355.
Ahmed MK Parvin E Arif M Islam MM Akter MS Khan MS 《Environmental monitoring and assessment》2011,182(1-4):197-204
The present investigation was undertaken to study the induction of DNA damage by lead chloride (PbCl(2)) in freshwater climbing perch Anabas testudineus using alkaline single cell gel electrophoresis (comet assay). Based on the LC(50) values of lead chloride of A. testudineus three different concentrations viz., 0.1, 1.0 and 2.0 mg/L were selected to expose fish. The DNA damage was observed in the gill, kidney and liver tissue as the percentage of DNA in comet tails and comet heads in the tissue of the exposed fish. DNA damage at different concentrations showed sensitivity to particular tissue. The liver tissue exhibited significantly (p < 0.01) higher DNA damage, followed by kidney and gill. However, the DNA damage was found to be dose dependent; at 2 mg/L of PbCl(2) the tail and head DNA of liver tissue were 57.84% and 39.49%, in kidney tissue the values were 52.36% and 44.97% whereas in gill tissue the values were 48.86% and 48.96% respectively. The current study explored the utility of the comet assay for in vivo laboratory studies using A. testudineus species for screening the genotoxic potential of lead chloride. 相似文献
356.
Ghrefat HA Jamarh A Al-Futaisi A Al-Abri B 《Environmental monitoring and assessment》2011,181(1-4):509-524
There are more than 4,000 falaj (singular of a peculiar dug channel) distributed in different regions in Oman. The chemical characteristics of the water in 42 falaj were studied to evaluate the major ion chemistry; geochemical processes controlling water composition; and suitability of water for drinking, domestic, and irrigation uses. GIS-based maps indicate that the spatial distribution of chemical properties and concentrations vary within the same region and the different regions as well. The molar ratios of (Ca + Mg)/Total cations, (Na + K)/Total cations, (Ca + Mg)/(Na + K), (Ca + Mg)/(HCO? + SO?), and Na/Cl reveal that the water chemistry of the majority of aflaj are dominated by carbonate weathering and evaporite dissolution, with minor contribution of silicate weathering. The concentrations of most of the elements were less than the permissible limits of Omani standards and WHO guidelines for drinking water and domestic use and do not generally pose any health and environmental problems. Some aflaj in ASH Sharqiyah and Muscat regions can be used for irrigation with slight to severe restriction because of the high levels of electrical conductivity, total dissolved solids, chloride, and sodium absorption ratio. 相似文献
357.
Ahmad Munir Chandio Abbas Ali Solangi Yasir Ahmed Shah Syed Ahsan Ali Shahzad Farrukh Rehman Abdul Jabeen Gul 《Environmental science and pollution research international》2021,28(2):1502-1518
Environmental Science and Pollution Research - This research investigates the dynamic interactive associations among sustainable investment in the energy sector, air pollution, and sustainable... 相似文献
358.
Ben Said Myriam Bousselmi Latifa Ghrabi Ahmed 《Environmental science and pollution research international》2021,28(13):15819-15827
Environmental Science and Pollution Research - In this study, we propose the development of a rapid and reliable method to control and to monitor microbial water quality. The methylene blue (MB)... 相似文献
359.
Usmani Muhammad Shahjahan Wang Jianling Ahmad Naveed Iqbal Muzaffar Ahmed Rahil Irfan 《Environmental science and pollution research international》2021,28(23):28848-28864
Environmental Science and Pollution Research - This study presents a comprehensive literature review and gives an insight into the increasing research trends that are based on the discipline of... 相似文献
360.
Buledi Jamil Ahmed Amin Sidra Haider Syed Iqleem Bhanger Muhammad Iqbal Solangi Amber R. 《Environmental science and pollution research international》2021,28(42):58994-59002
Environmental Science and Pollution Research - The extensive release of heavy metals into the natural water bodies has become globally prevalent from past few decades. Heavy metal toxicity is... 相似文献