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النتائج 2821 - 2830 من 4,937
A review of studies on urban energy performance evaluation النص الكامل
2019
Wang, Lei | Long, Ruyin | Chen, Hong | Li, Wenbo | Yang, Jiahui
Energy is a foundation for a city to create economic wealth, satisfy people’s desires, and achieve benefits. However, the increasing mismatch between energy supply and demand and the worsening of environmental pollution have highlighted the importance of improving urban energy performance, so the number of studies related to urban energy performance evaluation is increasing. Based on describing the authors, numbers, regional sources, and themes of these studies, this paper reviews and analyzes the conceptions, evaluation indicators, influencing factors, evaluation methods, and evaluation systems related to urban energy performance. Most countries have expressed concern about this topic. Researchers in China, Belgium, and the USA have had the most achievements and collaborations. The concept of urban energy performance further extends to a comprehensive performance. It is measured based on an input-output process. In addition to the original evaluation indicators, new desirable outputs and undesirable outputs are included. Industrial structure, energy price, population density, home car ownership, climate factors, Gini coefficient, health expenditure level, and unemployment rate are regarded as influencing factors. Therefore, a new framework of evaluation indicators and influencing factors is constructed. Stochastic frontier analysis (SFA) and data envelopment analysis (DEA) are commonly used to evaluate. With changes in conceptions, evaluation indicators, and influencing factors, the evaluation method should rather focus on measuring multiple input-output variables, determining the evaluation results and the impacts of factors at the same analysis stage, and highlighting policy orientations. As an important management tool, the evaluation system would continue to be studied and developed.
اظهر المزيد [+] اقل [-]Biosorption of nickel(II) and copper(II) ions from synthetic and real effluents by alginate-based biosorbent produced from seaweed Sargassum sp النص الكامل
2019
Barquilha, Carlos E. R. | Cossich, Eneida S. | Tavares, Célia R. G. | da Silva, Edson A.
In this study, the alginate-based biosorbent produced from seaweed Sargassum sp. was used in biosorption of Ni²⁺ and Cu²⁺ ions from synthetic solutions and real electroplating effluents. Biosorption kinetics, isotherms, pH effect, thermodynamic parameters, and sorption/desorption cycles were also evaluated. Kinetic studies show the sorption equilibrium can be obtained within 180 min for Ni²⁺ ions and 360 min for Cu²⁺ ions, and the adsorption kinetics data are well described by the pseudo-second order and diffusion in spherical adsorbents. Langmuir model can be well used to describe the biosorption isotherm data. The maximum sorption capacity (qₘₐₓ) and Langmuir constant (b) were up to 1.147 mmol g⁻¹ and 1.139 L mmol⁻¹ for Ni²⁺ ions and 1.640 mmol g⁻¹ and 4.645 L mmol⁻¹ for Cu²⁺ ions. The calculated thermodynamic parameters (ΔG°, ΔH°, and ΔS°) showed that the biosorption of Ni²⁺ and Cu²⁺ ions are predominantly a chemical phenomenon of endothermic nature, favorable, and spontaneous at the temperature ranges of 293–313 K. Partial desorption of the Ni²⁺ and Cu²⁺ ions on the biosorbent was achieved using acidic and saline eluents, allowing the biosorbent to be used in new sorption/desorption cycles. EDX analysis suggests an ion exchange mechanism between calcium ions on the biosorbent and target metals. Biosorption of Ni²⁺ and Cu²⁺ from real electroplating effluents with high concentrations of light metals becomes highly competitive, decreasing the amount of Ni²⁺ and Cu²⁺ ions biosorbed due to the ionic strength effect.
اظهر المزيد [+] اقل [-]Aging as the main factor controlling PAH and polar-PAC (polycyclic aromatic compound) release mechanisms in historically coal-tar-contaminated soils النص الكامل
2019
Boulangé, Marine | Lorgeoux, Catherine | Biache, Coralie | Michel, Julien | Michels, Raymond | Faure, Pierre
In industrial sites, historically contaminated by coal tar (abandoned coking and manufactured gas plants), other families of organic pollutants than the 16 PAHs (polycyclic aromatic hydrocarbons) classified by the US-EPA can occur and induce potential risk for groundwater resources. Polar PACs (polycyclic aromatic compounds), especially oxygenated and nitrogenated PACs (O-PACs and N-PACs), are present in the initial pollution and can also be generated over time (i.e., O-PACs). Their aqueous solubilities are much greater than those of the PAHs. For these reasons, we need to increase our knowledge on polar PACs in order to better predict their behavior and the potential on-site risk. Batch leaching tests were carried out under various conditions of temperature, ionic strength, and availability of pollutants to determine the mechanisms and key parameters controlling their release. The results show a release of low-molecular-weight PAHs and polar PACs mainly by dissolution, while higher molecular weight PAHs are mainly released in association with colloids. Aging mainly controls the former mechanism, and ionic strength mainly controls the latter. Temperature increased both dissolution and colloidal mobilization. The Raoult law predicts the PAC equilibrium concentration for soils presenting high pollutant availability, but this law overestimates PAC concentration in aged soils (low pollutant availability). This is mainly due to limitation of PAC diffusion within coal-tar particles with aging. The most soluble PACs (especially polar PACs) are the most sensitive to aging. For better prediction of the PAC behavior in soils and water resources management, aging needs to be taken into account.
اظهر المزيد [+] اقل [-]Efficacy of a school-based intervention to bring awareness about PCB contamination and exposure avoidance in Guánica, Puerto Rico النص الكامل
2019
Ramirez-Ortiz, Daisy | Almodóvar-Morales, Glenda L. | Hopwood, Samuel | Kumar, Naresh
Production of polychlorinated biphenyls (PCB) was banned in the US in 1970s. However, susceptible populations especially those living at/around the contaminated sites continue to be at a risk of elevated exposure to PCBs because information about the contamination (of the environment) and its associated health risks may not reach these populations. A recent study found the second highest concentration of PCBs ever recorded worldwide in the sediment samples of Guánica Bay, located in the southwestern part of Puerto Rico. PCB levels in fish from the bay were also higher than the tolerance limit of Food and Drug Administration (FDA), which motivated this research to initiate a school-based campaign to bring community awareness about the contamination of the bay and engage students in preventive strategies to reduce their exposure to PCBs. Surveys before and after the campaign were administered in the high school as well as in the communities of Guánica Municipality. The analyses of the survey data suggest that the campaign was effective in bringing awareness among schoolchildren (6.6% before versus 69.7% after the campaign; χ² ~ 60.4; p < 0.001) and strategies to reduce PCB exposure and its toxicity such as removing adipose tissues from seafood/fish and exercising. In the community, there was a significant decline in the consumption of seafood/fish harvested from the bay after the campaign (54.6% before versus 33% after the campaign; χ² ~ 10.85; p < 0.001). However, the awareness did not result in significant behavior modifications among schoolchildren, such as avoiding swimming and fishing in the bay. Given hazardous levels of PCBs and some students use the bay for various purposes, including one-third of community members still use seafood/fish harvested from the bay, attention of different stakeholders is warranted for clean-up efforts as well as engaging children and communities in PCB exposure avoidance strategies.
اظهر المزيد [+] اقل [-]Evaluate the effect of cadmium on levels of zinc in scalp hair and blood samples of smoker and nonsmoker psoriatic patients at different stage النص الكامل
2019
Samejo, Suraya | Kazi, Atif G. | Afridi, Hassan I. | Kazi, Tasneem G.
Psoriasis, a skin inflammatory disease, originates from dysregulated interactions of the immune system and environmental factors. In the present study, cadmium (Cd) and zinc (Zn) were analyzed in biological samples (blood and scalp hair) of smoker and nonsmoker males who have mild and severe psoriasis. The patients were evaluated according to criteria based on the standard clinical diagnosis and classified into mild and severe psoriasis groups using the Psoriasis Area Severity Index (PASI) score. Both elements were determined by atomic absorption spectrometry after matrix oxidation. In smoker psoriatic patients, the level of Cd in biological samples was significantly increased. The Zn was significantly decreased in smoker mild and severe psoriatic patients as related to nonsmokers’ referents and patients. The resulted data indicated that the levels of Zn in smoker referents were about 5.0% lower than nonsmoker’s referents. While the concentrations of Zn in blood samples of nonsmoker’s mild and severe psoriatic patients have 17.8 to 33.3% lower than nonsmoker’s referents. The results indicate that the level of Cd in blood samples of referent smokers has ≥ 25% than nonsmokers, whereas the psoriatic patients at different stages have two- to threefold higher Cd in both biological samples.
اظهر المزيد [+] اقل [-]The environmental condition of an estuarine ecosystem disturbed by pesticides النص الكامل
2019
Rodrigues, Elsa T. | Alpendurada, Maria Fátima | Guimaraes, Ana | Avó, Romeu | Ferreira, Bárbara | Pardal, Miguel A.
Knowledge regarding the concentration levels resulting from the use of agricultural pesticides may indicate the nature of the controls necessary to reduce environmental and human health risks to an acceptable level. Therefore, the main goal of the present work was to assess the spatial and temporal occurrence of 35 pesticides in the River Sado estuary (Portugal) in 2017 and evaluate its environmental condition, as data for estuarine ecosystems is scarce. Since pesticides are very susceptible to matrix effects promoted by environmental samples, to attain the main goal, we developed a fast and almost solvent-free environmentally friendly method with a good performance for both estuarine surface water and sediment samples. Quantified residues were determined mostly during summer, in line with the pesticide application period. Five herbicides (alachlor, bentazon, metobromuron, metribuzin and triclopyr) were measured in the water before and after the production season, suggesting a long-term aquatic exposure. Sediment samples were less contaminated, since a lower number of quantified pesticides were found in the study area, in lower frequencies and lower concentrations. No potential high adverse effects of the use of agricultural pesticides were expected on the aquatic organisms of the Sado estuary, even considering the potential combination effect of pesticide mixtures.
اظهر المزيد [+] اقل [-]Pb2+ adsorption by a compost obtained from the treatment of tobacco from smuggled cigarettes and industrial sewage sludge النص الكامل
2019
Seremeta, Daniele Cristina Hass | da Silva, Cleber Pinto | Zittel, Rosimara | de Campos, Sandro Xavier
The adsorption of Pb²⁺ by a compost obtained from the treatment of tobacco from smuggled cigarettes (SCT) and industrial sewage sludge (ISS) was investigated. The Pb²⁺ adsorption process was evaluated as function of different concentrations of adsorbent and adsorbate, pH variations, and contact time. Fourier transformed infrared spectroscopy (FTIR) and energy dispersive X-ray spectrometry (EDX) were adopted to obtain information regarding structural changes and a better understanding of the adsorption mechanism. The adsorbent maximum adsorption capacity for Pb²⁺, calculated using the Sips equation, was 21.454 mg/g with 3 g/L adsorbent at pH 5. The adsorption kinetics best adjustment was obtained using the pseudo-second-order model with a time of 240 min to reach the adsorption equilibrium. FTIR and EDX results suggest that Pb²⁺ might have bonded to phenolic, carboxylic, hydroxyl, and amine groups; they also show formation of organometallic complexes and cationic exchange between the compost and the solution. The study confirmed that the compost evaluated can be used as a potential adsorbent in environments contaminated with Pb²⁺.
اظهر المزيد [+] اقل [-]Bioaccumulation and health risk assessment of trace metals in fish from freshwater polyculture ponds in Chengdu, China النص الكامل
2019
Xu, Xiaoxun | Huo, Qinglin | Dong, Yuanyuan | Zhang, Shirong | Yang, Zhanbiao | Xian, Junren | Yang, Yuanxiang | Cheng, Zhang
The freshwater polyculture pond culturing occupied an important position in the aquaculture industry. Accumulation of trace metals was investigated in water, sediments, and fish (Carassius auratus, Cyprinus carpio, Ctenopharyngodon idellus) from typical polyculture ponds in Chengdu, China. The results showed most of the pond water in Chengdu were safe for fish cultivation. The Cd and Cr concentrations in sediment samples from sites S3, S4, and S9 which were near the industrial park and road with a high traffic volume were higher than those of the other sites. Cu, Cr, Fe, Zn, Mn, Ni, and Pb in sediments were unpolluted, while Cd was unpolluted to moderately polluted due to anthropogenic activities. Cu, Cd, and Pb in fish pond sediment of Chengdu had higher potential mobility under normal environmental circumstances. The trace metal concentrations in liver of three fish species were all higher than those in muscle tissues. The order of bioaccumulation factor (BAF) values for trace metals was Cr > Cu > Pb > Zn > Cd > Ni > 20. The concentrations of Cu, Cd, Pb, Zn, and Cr in the muscle of three fish species were all below the local and international maximum permissible levels. The target hazard quotient (THQ) and hazard index (HI) of trace metals in aquaculture fish ponds in Chengdu were lower than 1, which indicated that the consumption of grass, crucian, and common carp cultivated in the aquaculture ponds of Chengdu pose no health risk to the residents.
اظهر المزيد [+] اقل [-]Adsorptive desulfurization of dibenzothiophene (DBT) in model petroleum distillate using functionalized carbon nanotubes النص الكامل
2019
Sadare, Olawumi Oluwafolakemi | Daramola, Michael Olawale
Industrial hydrodesulfurization method has not been efficient for removal of dibenzothiophene (DBT) from petroleum distillates. Therefore, in this current study, adsorptive desulfurization (investigated in batch mode) was carried out using functionalized carbon nanotubes (FCNTs) to reduce the amount of DBT in a model diesel. Different techniques, such as, scanning electron microscope (SEM) equipped with energy-dispersive X-ray (EDX), were used to check the morphological structure and the elemental compositions of the adsorbent; Fourier transmission infrared (FTIR) was used to check the chemical functionalities of the adsorbent; and nitrogen physisorption at 77 K was used to check the surface area, pore size, and pore volume of the adsorbent. The results show that the FCNTs outperformed the non-functionalized carbon nanotubes (CNTs) during the desulfurization by about 10%, indicating the functionalization did improve the desulfurization performance of the CNTs. The % removal of DBT by the FCNTs and CNTs was 70.48 and 60.88%, respectively. It can be concluded that the acid treatment of CNTs enhanced its surface affinity for DBT, thus contributing to the improved adsorption performance of the adsorbent. The isotherm results show that Freundlich isotherm model described well the mechanism of the adsorption process for both CNTs and FCNTs. In addition, pseudo second-order kinetics describes the behavior of the adsorbents during the adsorption process. The results obtained in this study therefore show that functionalized CNTs could be efficient and potential adsorbent for removal of DBT in petroleum distillate (e.g., diesel), to meet up with the stringent policies regarding emission of sulfur oxides.
اظهر المزيد [+] اقل [-]Analysis of vegetation dynamics, drought in relation with climate over South Asia from 1990 to 2011 النص الكامل
2019
Shahzād, ʻAlī | Henchiri, Malak | Yao, Fengmei | Zhang, Jiahua
Drought is the most complex climate-related disaster issue in South Asia, because of the various land-cover changes, vegetation dynamics, and climates. The aims of the current research work were to analyze the performance of AVHRR Normalized Difference Vegetation Index (NDVI) and spatiotemporal differences in vegetation dynamics on a seasonal basis by correlating the results with NASA’s MERRA precipitation and air temperature for monitoring vegetation dynamics and drought over South Asia. Our approach is based on the use of AVHRR NDVI data and NASA’s MERRA rainfall and air temperature data (1990–2011). Due to the low vegetation and dryness, the NDVI is more helpful in describing the drought condition in South Asia. There were rapid increases in NDVI, VHI, and VCI from April to October. Monthly NDVI, VHI, and VCI stabilize in September and improved once more in October and then show a declining trend in December. The monthly PCI, TCI, VHI, and VCI values showed that the South Asia goes through an extreme drought in 2000, which continues up to 2002, which lead the highest water stress. Spatial correlation maps among NDVI, precipitation, air temperature, VHI, and VCI on a seasonal basis. The correlation between NDVI and precipitation showed a significantly higher correlation value in JJA and SON seasons; the spatial correlation between NDVI and air temperature showed significant high values in DJF, JJA, and SON periods, while the correlation between VHI and TCI showed a significantly higher values in MAM and SON seasons, which indicated a good sign for dryness monitoring, mainly for farming regions during these seasons in South Asia. It was confirmed that these indexes are a comprehensive drought monitoring indicator and a step to monitoring the climate change in South Asia, which will play a relevant role ongoing studies on vegetation types, monitoring climate change, and drought over South Asia.
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