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结果 4021-4030 的 4,309
Toward multi-day-ahead forecasting of suspended sediment concentration using ensemble models 全文
2017
Alizadeh, Mohamad Javad | Jafari Nodoushan, Ehsan | Kalarestaghi, Naghi | Chau, Kwok Wing
This study explores two ideas to made an improvement on the artificial neural network (ANN)-based models for suspended sediment forecasting in several time steps ahead. In this regard, both observed and forecasted time series are incorporated as input variables of the models when applied for more than one lead time. Secondly, least-square ensemble models employing multiple wavelet-ANN models are developed to increase the performance of the single model. For this purpose, different wavelet families are linked with the ANN model and performance of each model is evaluated using error measures. The Skagit River near Mount Vernon in Washington county is selected as the case study. The daily flow discharge and suspended sediment concentration (SSC) in the current day are considered as input variables to predict suspended sediment concentration in the next day. For more lead times, the input structure is updated by adding the forecast of SSC in the previous time step. Results of this study demonstrate that incorporating both observed and predicted variables in the input structure improves performance of conventional models in which those only employ observed time series as input variables. Moreover, ensemble model developed for each lead time outperforms the best single wavelet-ANN model which indicates superiority of the ensemble model over the other one. Findings of this study reveal that acceptable forecasts of daily suspended sediment concentration up to 3 days in advance can be achieved using the proposed methodology.
显示更多 [+] 显示较少 [-]Retrospective biomonitoring of mercury and other elements in museum feathers of common kestrel Falco tinnunculus using instrumental neutron activation analysis (INAA) 全文
2017
Movalli, Paola | Bode, Peter | Dekker, René | Fornasari, Lorenzo | van der Mije, Steven | Yosef, Reuven
This study examines the potential to use instrumental neutron activation analysis (INAA) to explore temporal and geographical variation in exposure to heavy metals and other selected elements in common kestrel Falco tinnunculus using feathers from a natural history collection. The study gathered samples of two breast feathers from each of 16 adult male kestrel specimens from Naturalis Biodiversity Centre, collected in The Netherlands between 1901 and 2001. Feather samples were analysed for more than 50 elements, using INAA at the Reactor Institute Delft. Results (in mg/kg dw) were transformed into ratios of milligram of element per millimetre of feather length. The distribution of the mass fractions and ratios was plotted for each element against time and by geographical area. Observed mass fractions and/or ratios are discussed for selected elements (Hg, Cd, Zn, Pt, Pd, Se, Al, Rb, As, Sb, Cr, V, Cl, Br) known to have, at certain concentrations, adverse effects on raptors. Some samples show mass fractions of certain elements (Cr, Cd, Se, As) above levels known to have adverse effects. We conclude that the analysis of museum feathers using INAA provides reference values for concentrations of selected elements, including those of high societal concern such as Hg and Cd, against which to assess concentrations of these elements in feathers of present-day living raptor populations.
显示更多 [+] 显示较少 [-]UV-C as a means to combat biofilm proliferation on prehistoric paintings: evidence from laboratory experiments 全文
2017
Pfendler, Stéphane | Einhorn, Olympe | Bousta, Faisl | Khatyr, Abderrahim | Alaoui-Sossé, Laurence | Aleya, Lotfi | Alaoui-Sossé, Badr
A laboratory investigation of UV-C effects was conducted over a 62-h period: a much higher dose than in classic UV-C treatment was applied to five pigments and two painting binders used by prehistoric humans. Colorimetric parameters were compared to a control to see if UV-C can change pigment and binder color. Infrared spectroscopy, scanning electron microscopy, inductively coupled plasma and X-ray crystallography were also carried out to confirm colorimetric measurement. In order to understand how microorganism may physically deteriorate paintings, limestone blocks were painted and monitored until their complete colonization by algae, cyanobacteria, fungi and/or mosses. The results show that UV-C has no effect on mineral compounds. Conversely, it is noteworthy that binder color changed under both UV-C light conditions as well as in visible light. Concerning painted blocks, a fast proliferation has been observed with deterioration of the paintings. These results show the high importance of treating biofilm as soon as possible. Moreover, these findings may be a promising avenue inducing cave managers to use friendly UV-C light to treat contaminated cave paintings and also in the prevention of biodeterioration by lampenflora.
显示更多 [+] 显示较少 [-]Assessment of hospitalization and mortality from exposure to PM10 using AirQ modeling in Ilam, Iran 全文
2017
Nikoonahad, Ali | Naserifar, Razi | Alipour, Vali | Poursafar, Ayub | Miri, Mohammad | Ghafari, Hamid Reza | Abdolahnejad, Ali | Nemati, Sepideh | Mohammadi, Amir
The aims of this study were to assess the health impact of PM₁₀ on inhabitants and to investigate the trend of PM₁₀ concentrations in Ilam, Iran, from 2012 to 2015. For these aims, daily average concentration of PM₁₀ was obtained from continuous monitoring stations in the study area. Mortality and morbidity due to PM₁₀ were assessed by AirQ software developed by World Health Organization (WHO). Based on the results, the annual mean concentrations of PM₁₀ in all of years were more than WHO guideline and PM₁₀ concentration had a decreasing trend in this study period. Total mortality attributed to PM₁₀ was found to be 49 cases in 2012, 25 in 2013, and 33 in 2014. Hospital admission due to respiratory diseases was the most impact due to PM₁₀. Increase in relative risk (RR) with every 10 μg/m³ increase in PM₁₀ from 2012 to 2015 years for total mortality, respiratory disease hospitalization, and hospital admissions were 0.6, 0.8, and 0.9%, respectively. The results of this study indicated that air pollution is one of the major problems in this urban area and AirQ model as simple tool can help to design preventive and controlling programs in order to reduce human health effects of pollutants.
显示更多 [+] 显示较少 [-]Attempts to minimize nitrogen oxide emission from diesel engine by using antioxidant-treated diesel-biodiesel blend 全文
2017
Rashedul, Hasan Khondakar | Kalam, Md Abdul | Masjuki, Haji Hassan | Teoh, Yew Heng | How, Heoy Geok | Monirul, Islam Mohammad | Imdadul, Hassan Kazi
The study represents a comprehensive analysis of engine exhaust emission variation from a compression ignition (CI) diesel engine fueled with diesel-biodiesel blends. Biodiesel used in this investigation was produced through transesterification procedure from Moringa oleifera oil. A single cylinder, four-stroke, water-cooled, naturally aspirated diesel engine was used for this purpose. The pollutants from the exhaust of the engine that are monitored in this study are nitrogen oxide (NO), carbon monoxide (CO), hydrocarbon (HC), and smoke opacity. Engine combustion and performance parameters are also measured together with exhaust emission data. Some researchers have reported that the reason for higher NO emission of biodiesel is higher prompt NO formation. The use of antioxidant-treated biodiesel in a diesel engine is a promising approach because antioxidants reduce the formation of free radicals, which are responsible for the formation of prompt NO during combustion. Two different antioxidant additives namely 2,6-di-tert-butyl-4-methylphenol (BHT) and 2,2′-methylenebis(4-methyl-6-tert-butylphenol) (MBEBP) were individually dissolved at a concentration of 1% by volume in MB30 (30% moringa biodiesel with 70% diesel) fuel blend to investigate and compare NO as well as other emissions. The result shows that both antioxidants reduced NO emission significantly; however, HC, CO, and smoke were found slightly higher compared to pure biodiesel blends, but not more than the baseline fuel diesel. The result also shows that both antioxidants were quite effective in reducing peak heat release rate (HRR) and brake-specific fuel consumption (BSFC) as well as improving brake thermal efficiency (BTE) and oxidation stability. Based on this study, antioxidant-treated M. oleifera biodiesel blend (MB30) can be used as a very promising alternative source of fuel in diesel engine without any modifications.
显示更多 [+] 显示较少 [-]Polycyclic aromatic hydrocarbons in the leaves of twelve plant species along an urbanization gradient in Shanghai, China 全文
2017
Liang, Jing | Fang, Hailan | Zhang, Taolin | Wang, Xingxiang
Plants, particularly their leaves, play an important role in filtering both gas-phase and particle-phase polycyclic aromatic hydrocarbons (PAHs). However, many studies have focused on the accumulation and adsorption functions of plant leaves, possibly underestimating the effects that plants have on air quality. Therefore, eight tree species from different locations in Shanghai were selected to assess PAH filtering (via adsorption and capture) using washed and unwashed plant leaves. The differences in the total PAH contents in the washed leaves were constant for the different species across the different sampling sites. The PAH levels decreased in the following order: industrial areas > traffic areas > urban areas > background area. The PAH compositions in the different plant leaves were dominated by fluorene (Fle), phenanthrene (Phe), anthracene (Ant), chrysene (Chr), fluoranthene (Flu), and pyrene (Pyr); notably, Phe accounted for 49.4–76.7% of the total PAHs. By comparing the PAH contents in the washed leaves with the PAH contents in the unwashed leaves, Pittosporum tobira (P. tobira), Ginkgo biloba (G. biloba), and Platanus acerifolia (P. acerifolia) were found to be efficient species for adsorbing PAHs, while Osmanthus fragrans (O. fragrans), Magnolia grandiflora (M. grandiflora), and Prunus cerasifera Ehrh. (P. cerasifera Ehrh.) were efficient species for capturing PAHs. The efficiencies of the plant leaves for the removal of PAHs from air occurred in the order of low molecular weight > medium molecular weight > high molecular weight PAHs.
显示更多 [+] 显示较少 [-]Effects on heavy metal accumulation in freshwater fishes: species, tissues, and sizes 全文
2017
Jia, Yuyu | Wang, Lin | Qu, Zhipeng | Wang, Chaoyi | Yang, Zhaoguang
Three fish species (Carassius auratus, Pelteobagrus fulvidraco, and Squaliobarbus curriculus) were collected from Xiang River near Changsha City, Southern China. The concentrations of heavy metals including arsenic (As), cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn), lead (Pb), and zinc (Zn) in the muscle, gill, and liver of three species were determined by the inductively coupled plasma mass spectrometry method. One-way analysis of variance (ANOVA) was introduced to determine the significant variations (p < 0.05) of heavy metals. Livers were found to accumulate Cd and Cu due to the metallothionein proteins. High levels of Mn and Pb in the gills indicated that the main uptake pathway of these heavy metals was from the water. The carnivorous species, P. fulvidraco, was found to accumulate the highest levels of toxic elements (As, Cd, and Pb), while relatively high concentrations of nutrient elements (Cu, Fe, Mn, and Zn) were accumulated in omnivorous species (C. auratus and S. curriculus). According to the results of Pearson’s correlation analysis, there were few significant relationships at p < 0.01 level between the concentrations of the analyzed elements and the fish sizes. The results of risk assessment indicated that exposure to the toxic heavy metals from fish muscle consumption posed no non-carcinogenic health risk to local inhabitants.
显示更多 [+] 显示较少 [-]Toxicity and biodegradation of ibuprofen by Bacillus thuringiensis B1(2015b) 全文
2017
Marchlewicz, Ariel | Guzik, Urszula | Hupert-Kocurek, Katarzyna | Nowak, Agnieszka | Wilczyńska, Sylwia | Wojcieszyńska, Danuta
In recent years, the increased intake of ibuprofen has resulted in the presence of the drug in the environment. This work presents results of a study on degradation of ibuprofen at 25 mg L⁻¹ in the presence of glucose, as an additional carbon source by Bacillus thuringiensis B1(2015b). In the cometabolic system, the maximum specific growth rate of the bacterial strain was 0.07 ± 0.01 mg mL⁻¹ h⁻¹ and K ₛμ 0.27 ± 0.15 mg L⁻¹. The maximum specific ibuprofen removal rate and the value of the half-saturation constant were q ₘₐₓ = 0.24 ± 0.02 mg mL⁻¹ h⁻¹ and K ₛ = 2.12 ± 0.56 mg L⁻¹, respectively. It has been suggested that monooxygenase and catechol 1,2-dioxygenase are involved in ibuprofen degradation by B. thuringiensis B1(2015b). Toxicity studies showed that B. thuringiensis B1(2015b) is more resistant to ibuprofen than other tested organisms. The EC50 of ibuprofen on the B1 strain is 809.3 mg L⁻¹, and it is 1.5 times higher than the value of the microbial toxic concentration (MTCₐᵥg). The obtained results indicate that B. thuringiensis B1(2015b) could be a useful tool in biodegradation/bioremediation processes.
显示更多 [+] 显示较少 [-]Lactational exposure to abamectin induced mortality and adverse biochemical and histopathological effects in suckling pups 全文
2017
Mossa, Abdel-Tawab H. | Abdel Rasoul, Mona A. | Mohafrash, Samia M. M.
Information about the adverse effects of lactation transfer of abamectin (ABA) is important for human health, especially in the third-world countries where breastfeeding is the only source of nutrition for infants. So, the present study was undertaken to evaluate the adverse effects of breastfeeding exposure to ABA on oxidative damage and liver and kidney dysfunction in suckling rats. Dams were orally administered ABA at a doses 22.10, 11.05, and 2.21 mg a.i./kg b.wt from postnatal day 1 (PND1) until day 20 (PND20). The signs of toxicity and high mortality were recorded in suckling male (67.5%) and female (55.0%) pups whose mother exposed to the ABA at dose 22.1 mg a.i./kg b.wt. ABA induced significantly decrease in body weights of mothers and their male and female pups and significant increase in relative liver weights. It caused oxidative stress in the liver and kidney of mothers and their pups by increasing the level of malondialdehyde (MDA) and decreased activities of superoxide dismutase (SOD) and glutathione-transferase (GST). ABA altered the level of serum liver and kidney dysfunction biomarkers either in the mothers or their male and female pups in a dose-dependent manner. It caused histopathological alterations in the liver and kidney tissues. It can be decided that ABA was accumulated in mother’s milk, transferred through breast feeding, and induced mortality in their suckling pups. It caused oxidative stress, lipid peroxidation, and biochemical and histopathological alterations in the liver and kidney of mothers and their suckling pups. The results in the present study add some information about the adverse effect of lactation transfer of ABA, which is important for human health in the third-world countries where breastfeeding may be the only source of nutrition for infants in the first and most critical weeks of life.
显示更多 [+] 显示较少 [-]Influence of alternating current on the adsorption of indigo carmine 全文
2017
Kesraoui, Aida | Selmi, Taher | Seffen, Monig | Brouers, François
The main purpose of this work is to study the effect of a new process of accelerating which consist to couple the electrochemical process with the adsorption to remove an anionic dye, the indigo carmine. That is why, we investigated the effects of the new process of accelerating the adsorption process by using alternating current (AC) on the retention of an anionic dye, the indigo carmine. The adsorption capacity of dye (mg/g) was raised with the raise of current voltage in solution, temperature, and initial indigo carmine concentration and decreased with the increase of initial solution pH, current density, and mass of carbon. The results demonstrate that the removal efficiency of 97.0 % with the current voltage of 15 V is achieved at a current density of 0.014 A/cm², of pH 2 using zinc as electrodes and contact time of 210 min for adsorption in the presence of AC. Concerning the adsorption without AC, the results obtained showed that for an initial concentration equal to 20 mg/L, more than 95 % amount of adsorbed dye was retained after 405 min of contact in batch system. The comparison between adsorption in the presence and absence of an alternating current shows the importance of the alternating current in the acceleration of the adsorption method and improve the performances of FILTRASORB 200. For both cases, the adsorption mechanism follows the fractal kinetics BSf(n,α) model and the Brouers–Sotolongo isotherm model provides a good fit of the experimental data for both adsorption with and without alternating current.
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