خيارات البحث
النتائج 3221 - 3230 من 5,014
Environmental and economic impacts of better cotton: a panel data analysis النص الكامل
2019
Zulfiquar, Sundas | Yasin, Muhammad Asim | Khuda Bakhsh, | Ali, Rafaqet | Samiullah, | Munir, Saad
Better cotton is introduced with the aim of a reduction in the use of environmentally detrimental farm inputs in order to attain sustainable cotton production. The present study is designed to assess the environmental and economic effects of better cotton in Pakistan using panel data comprising of two cropping seasons, 2015 and 2016. Panel methods were used in the present study. Findings show that better cotton increases the gross margin by 37% and yield by 9%, whereas it results in decreasing seed rate by 6%, fertilizers by 7%, pesticides by 7%, and irrigation by 14%. Since better cotton involves more labor use due to higher yield, labor increases by 3%. The study concludes that better cotton is more economically and environmentally sustainable than conventional cotton. The study suggests that public private partnership will be a good strategy to diffuse better cotton technologies among the farming communities.
اظهر المزيد [+] اقل [-]Improving the attractiveness and accessibility of campus green space for developing a sustainable university environment النص الكامل
2019
Li, Xinqin | Ni, Guoping | Dewancker, Bart
A growing body of research has investigated the vital effects of urban greening. However, the green space on campus, also recognized as an important element of urban greening and providing many benefits to college students, has gained very limited attention. In developing China, after nearly 20 years of campus construction climax, the speed of expansion has dropped significantly and the focus of a sustainable and optimized green campus has emerged. Improving the accessibility, availability, and attractiveness is a control determining if the green spaces can realize their values. Therefore, this study, taking a case, aims to explore and better understand students’ usage conditions, perceptions, and demands about campus green spaces. On Yijin campus in Hangzhou, China, through the questionnaire among 590 students, and accessibility analysis based on Space syntax theory, we have revealed that the negative usage condition of green spaces: most students rarely or occasionally visit the green space, and the visit time is concentrated in the afternoon and after class but rarely in the morning. Besides, students’ gender and growth surroundings have little influence on the perception of campus green space, but the plant configuration, seasonal color richness, and facilities required at different spaces will affect. In addition, the ranking of accessibility analyzed by Space syntax theory is similar to campus convenience considered by students. In the conclusions, suggestions are made about how to fulfill students’ requirements and improve the attractiveness and accessibility of campus green spaces so that they may inform to the growth of emerging colleges and universities in other cities and countries undergoing campus construction climax.
اظهر المزيد [+] اقل [-]Occurrence and removal of sulfonamides and their acetyl metabolites in a biological aerated filter (BAF) of wastewater treatment plant in Xiamen, South China النص الكامل
2019
Wang, Dapeng | Zhang, Xian | Yan, Changzhou
Most sulfonamides, widely used around the world, are excreted via feces and urine along with their metabolites in humans and animals. Therefore, understanding the potential removal pathway of sulfonamides and their metabolites in wastewater treatment systems is of importance. The occurrence and fate of four sulfonamides and their acetyl metabolites in wastewater and sludge in a biological aerated filter in Xiamen city were evaluated. Six of the target compounds were detected in wastewater, but only parent compounds were detected in sludge. The highest concentration in wastewater was acetyl-sulfamethoxazole (Ac-SMZ) with a concentration of 75.2 ng/L. Removal efficiency and mass load in wastewater treatment systems were calculated. In terms of the overall removal efficiency, they ranged from 24.4 to 100%. The removal efficiencies of sulfamerazine (SM1), sulfamethazine (SM2), and sulfadiazine (SD) were up to 100% while N-acetyl sulfamerazine (Ac-SM1) showed the lowest removal efficiency. Biodegradation was the dominant remove pathway according to the mass balance analysis while SD and SM2 were sludge adsorption. The results can provide an insight into the fate of target sulfonamides in BAF systems and provide data to assess their potential ecological risks.
اظهر المزيد [+] اقل [-]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⁺.
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