خيارات البحث
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Lignocellulosic materials as soil–cement brick reinforcement النص الكامل
2022
Sabino, Ticyane Pereira Freire | Coelho, Nayane Pereira Freire | Andrade, Nayhara Camila | Metzker, Stefânia Lima Oliveira | Viana, Queilla Santos | Mendes, Juliana Farinassi | Mendes, Rafael Farinassi
The need for environmental preservation requires civil engineering to reach new concepts and technical solutions aiming at the sustainability of its activities and products. In this context, this study aimed to evaluate the effect of using different types and percentages of vegetable particles on the physical, mechanical, and thermal properties of soil–cement bricks. Bamboo, rice husk, and coffee husk particles at 1.5 and 3% percentages and a control treatment not using the particle were evaluated. The chemical properties, shrinkage, compaction, consistency limits, and grain size were characterized for the soil; and the anatomical, chemical, and physical properties for the lignocellulosic particles. The bricks were produced using an automatic press and characterized after the curing process for density, water absorption, porosity, loss of mass by immersion, compressive strength, durability, and thermal conductivity. The increase in the lignocellulosic waste percentage caused a mechanical strength decrease and bricks’ porosity and water absorption increase. However, it caused a decrease in density and an enhancement in loss of mass and thermal insulation properties. The bricks produced with rice husk obtained the best results in terms of mechanical and thermal properties, and were still among the best treatments for physical properties, standing out among the lignocellulosic waste as an alternative raw material source for soil–cement brick production.
اظهر المزيد [+] اقل [-]Three-season rotation of chicory–tobacco–peanut with high biomass and bioconcentration factors effectively remediates cadmium-contaminated farmland النص الكامل
2022
Chen, Linhan | Yang, Wenjun | Yang, Yang | Tu, Pengfei | Hu, Shengnan | Zeng, Qingru
Traditional phytoremediation is one approach to remediate heavy metal pollution. In developing countries, the key factor in promoting practical application of phytoremediation in polluted soils is selecting suitable plants that are tolerant to heavy metals and also produce products with economic value. Therefore, a field experiment was conducted with a three-season chicory–tobacco–peanut rotation to determine effects on remediation of cadmium (Cd)-contaminated farmland in China. All crops had strong Cd accumulation capacity, with bioconcentration factors of 6.61 to 11.97 in chicory, 3.85 to 21.61 in tobacco, and 1.36 to 7.0 in peanut. Yield of total dry biomass reached 32.4 t ha⁻¹, and the Cd phytoextraction efficiency was 10.3% per year. Aboveground tissues of the three crops accounted for 83.9 to 91.2% of total biomass in the rotation experiment. Cd content in peanut grain and oil met the National Food Safety Standard of China (0.5 mg kg⁻¹, GB 2762–2017) and the Food Contaminant Limit of the European Union (0.1 mg kg⁻¹, 18,812,006). Therefore, in addition to phytoremediation of Cd-contaminated soils, the chicory–tobacco–peanut rotation system can also produce economic benefits for local farmers.
اظهر المزيد [+] اقل [-]Competency of groundwater recharge of irrigated cotton field subjacent to sowing methods, plastic mulch, water productivity, and yield under climate change النص الكامل
2022
Saeed, Muhammad | Maqbool, Ahsan | Ashraf, Muhammad Adnan | Arshad, Muḥammad | Maḥmūd, Kāshif | ʻUs̲mān, Muḥammad | Farid, Muhammad Arslan
Competency of groundwater recharge of irrigated cotton field subjacent to sowing methods, plastic mulch, water productivity, and yield under climate change النص الكامل
2022
Saeed, Muhammad | Maqbool, Ahsan | Ashraf, Muhammad Adnan | Arshad, Muḥammad | Maḥmūd, Kāshif | ʻUs̲mān, Muḥammad | Farid, Muhammad Arslan
Irrigated agriculture is a foremost consumer of water resources to fulfill the demand for food and fiber with an increasing population under climate changes; cotton is no exception. Depleting groundwater recharge and water productivity is critical for the sustainable cotton crop yield peculiarly in the semiarid region. This study investigated the water productivity and cotton yield under six different treatments: three sowing methods, i.e., flat, ridge, and bed planting with and without plastic mulch. Cotton bed planting without mulch showed maximum water productivity (0.24 kg.m⁻³) and the highest cotton yield (1946 kg.ha⁻¹). Plastic mulching may reduce water productivity and cotton yield. HYDRUS-1D unsaturated flow model was used to access the groundwater recharge for 150 days under six treatments after model performance evaluation. Maximum cumulative recharge was observed 71 cm for the flat sowing method without plastic mulch. CanESM2 was used to predict climate scenarios for RCP 2.6, 4.5, and 8.5 for the 2050s and 2080s by statistical downscale modeling (SDSM) using historical data from 1975 to 2005 to access future groundwater recharge flux. Average cumulative recharge flux declined 36.53% in 2050 and 22.91% in 2080 compared to 2017 without plastic mulch. Multivariate regression analysis revealed that a maximum 23.78% reduction in groundwater recharge could influence future climate change. Further study may require to understand the remaining influencing factor of depleting groundwater recharge. Findings highlight the significance of climate change and the cotton sowing method while accessing future groundwater resources in irrigated agriculture.
اظهر المزيد [+] اقل [-]Competency of groundwater recharge of irrigated cotton field subjacent to sowing methods, plastic mulch, water productivity, and yield under climate change النص الكامل
2022
Saeed, Muhammad | Maqbool, Ahsan | Ashraf, Muhammad Adnan | Arshad, Muhammad | Mehmood, Kashif | Usman, Muhammad | Farid, Muhammad Arslan | Conferencia de Rectores de las Universidades Españolas | Consejo Superior de Investigaciones Científicas (España) | Maqbool, Ahsan [0000-0002-5968-3390] | Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
Irrigated agriculture is a foremost consumer of water resources to fulfill the demand for food and fiber with an increasing population under climate changes; cotton is no exception. Depleting groundwater recharge and water productivity is critical for the sustainable cotton crop yield peculiarly in the semiarid region. This study investigated the water productivity and cotton yield under six different treatments: three sowing methods, i.e., flat, ridge, and bed planting with and without plastic mulch. Cotton bed planting without mulch showed maximum water productivity (0.24 kg.m-3) and the highest cotton yield (1946 kg.ha-1). Plastic mulching may reduce water productivity and cotton yield. HYDRUS-1D unsaturated flow model was used to access the groundwater recharge for 150 days under six treatments after model performance evaluation. Maximum cumulative recharge was observed 71 cm for the flat sowing method without plastic mulch. CanESM2 was used to predict climate scenarios for RCP 2.6, 4.5, and 8.5 for the 2050s and 2080s by statistical downscale modeling (SDSM) using historical data from 1975 to 2005 to access future groundwater recharge flux. Average cumulative recharge flux declined 36.53% in 2050 and 22.91% in 2080 compared to 2017 without plastic mulch. Multivariate regression analysis revealed that a maximum 23.78% reduction in groundwater recharge could influence future climate change. Further study may require to understand the remaining influencing factor of depleting groundwater recharge. Findings highlight the significance of climate change and the cotton sowing method while accessing future groundwater resources in irrigated agriculture. | Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. | Peer reviewed
اظهر المزيد [+] اقل [-]Is there any convergence in the CO2 emission efficiency of airlines? النص الكامل
2022
Kaya Aydin, Gizem | Aydin, Umut
This paper examines the CO₂ emission efficiency of airlines in the years 2011 and 2018 by using the Atmosfair Airline Index. This index gives reliable results since it encompasses data from more than 100 airlines and considers important variables in the calculation of CO₂ emissions. Firstly, we investigate the regional differences and the effect of the share of government ownership in the CO₂ emission efficiency of airlines. These factors have not been taken into account in other studies by using such a comprehensive index. Secondly, by utilizing the Barro and Sala-i Martin model that is commonly used to examine the regional income convergence model in economics, we also check whether there is a convergence in the CO₂ emission efficiency of airlines or not. As a result, in terms of efficiency growth, we find that airlines in Europe are more successful compared to airlines from other regions. Furthermore, increases in the share of government ownership in airlines negatively affect the CO₂ emission efficiency in Asia, whereas it is insignificant in Europe and America. Moreover, there is no convergence in the CO₂ emission efficiency of airlines from all regions. This shows that low-efficient airlines are not catching up with high-efficient airlines. Lastly, we find that charter airlines are more efficient in terms of CO₂ emissions.
اظهر المزيد [+] اقل [-]The employment effect of Chinese industrial enterprises embedded in environmental cost-adjusted global value chains النص الكامل
2022
Wang, Shuhong | Chen, Hanxue | Yin, Kedong
The employment effect of enterprises embedded in global value chains (GVCs) has important theoretical value, but existing research has ignored the impact of environmental costs on employment under the division of labor system within the value chain. By constructing a GVC-embedded index considering environmental costs, this study investigates the impact of Chinese industrial enterprises’ embedding into GVCs on employment at both the theoretical and empirical levels. It is found that when the environmental cost is considered, the improvement of GVC embeddedness has a significant inhibiting effect on employment, especially for female laborers, lower-skilled laborers, state-owned enterprises, private enterprises, and enterprises in the eastern region of China. The research also shows that when considering environmental costs, the labor cost increase effect enhances the negative effect of increased GVC embeddedness on employment, while the innovation promotion effect and the foreign direct investment effect serve to mitigate the negative effect. The results provide a reference for developing countries seeking to effectively protect people’s livelihood and employment while achieving a leap in the division of labor along the green value chain.
اظهر المزيد [+] اقل [-]Sustainability assessment of wastewater treatment systems using cardinal weights and PROMETHEE method: case study of Morocco النص الكامل
2022
Makan, Abdelhadi | Gouraizim, Mohamed | Fadili, Ahmed
To cope with water scarcity, Morocco needs to integrate the reuse of treated wastewater fully into its water management strategies. However, this option imposes several concerns about the appropriate wastewater treatment system (WWTS) whose performance is balanced by technical, environmental, financial, and societal sustainability. To deal with these challenges, the present study aims to assess the sustainability of five WWTS using the cardinal (CAR) and PROMETHEE methods. After hierarchizing the criteria and identifying the WWTS, two separate surveys were performed in order to rank criteria and alternatives by preference strength. The delivered rankings were converted, then, respectively into cardinal weights (criteria) and cardinal scores (alternatives). The PROMETHEE rankings showed that the membrane systems are the most sustainable followed by trickling filters, while the infiltration-percolation is the least sustainable WWTS. The activated sludge and lagoon systems were incomparable using PROMETHEE I partial ranking, and they were both ranked in the third position of sustainability. In contrast, PROMETHEE II complete ranking favored the activated sludge than lagoon systems due to its slightly high net outranking flow. The stability intervals indicated that the weights of all criteria could not affect the two first actions, which is mainly due to the high precision and robustness of the CAR method in eliciting weights. Finally, each criterion affected variably the sustainability of WWTS according to their characteristics, but overall, the process efficiency is the key factor (21.07% of weight) to reaching higher sustainability levels in addition to gaseous emissions (12.41% of weight), flexibility (8.32% of weight), and energy requirement (7.50% of weight).
اظهر المزيد [+] اقل [-]A comprehensive method to prevent top-coal spontaneous combustion utilizing dry ice as a fire extinguishing medium: test apparatus development and field application النص الكامل
2022
Qin, Yueping | Guo, Wenjie | Xu, Hao | Song, Yipeng | Chen, Youqiang | Ma, Liwei
There is a high potential for coal spontaneous combustion (CSC) above the roof beams of supports during the mining-stopped period. Early detection of temperature abnormal zones and corresponding measures are necessary to prevent CSC. In this work, a top-coal temperature measurement method was proposed, combining the coal surface temperature detection and the drilling temperature observation. Furthermore, an apparatus was developed that dramatically increases the rate of dry ice sublimation, resulting in the rapid release of cryogenic carbon dioxide gas. The device utilizes water from firefighting pipes in underground coal mines as a heat source for dry ice sublimation without electrical energy and has been applied and validated taking Silaogou Coal Mine in China as a field test site. Specifically, we found that during the stoppage period, the coal above the supports near the air inlet tunnel is more likely to appear hot spots; the carbon dioxide gas generated by the dry ice phase change device can quickly reduce the hot spots temperature, and the coal temperature does not rebound after the gas injection is stopped. Based on the above analysis, this work can effectively prevent the early top-coal spontaneous combustion during the stop mining period.
اظهر المزيد [+] اقل [-]Does green credit policy affect corporate debt financing? Evidence from China النص الكامل
2022
Li, Weian | Cui, Guangyao | Zheng, Minna
Green finance is one of the most important ways to help companies achieve green transformation and development. We construct a quasi-natural experiment with the “Green Credit Guidelines” and establish a difference-in-differences model to empirically test the implementation effect of the green credit policy in China. The results show that after the implementation of China’s green credit policy, the debt financing scale of listed companies in heavily polluting industries has decreased significantly, the debt financing cost has increased significantly, and the debt financing maturity has been shortened significantly, indicating that the green credit policy has inhibited the debt financing of heavily polluting enterprises. We further find that this inhibition has also been affected by the nature of controlling shareholders, environmental information disclosure levels, regional environmental regulations and regional financial development levels. China’s green credit policy has played a role in guiding listed companies to go green through the redistribution of debt financing.
اظهر المزيد [+] اقل [-]Buffer effect of MgO on Na2SO3 to stabilize S(IV) for the enhancement in simultaneous absorption of NOx and SO2 from non-ferrous smelting gas النص الكامل
2022
Huang, Wenjun | Li, Sichao | Wang, Hongbin | Cui, Peng | Xu, Haomiao | Cheng, Can | Qu, Zan | Yan, Naiqiang
Oxidation–reduction-absorption based on sulfite is a promising process for simultaneous removal of NOₓ and SO₂. However, excessive oxidation of sulfite and competitive absorption between NOₓ and SO₂ limit its application. A matching strategy between antioxidants and alkaline agents has been proposed to solve these problems and enhance the absorption process. The comparison results of inhibitors showed that hydroquinone exhibited long-term high-efficiency inhibition of S(IV) (SO₃²⁻/HSO₃⁻) oxidation. The comparison of alkaline agents showed that the Na₂SO₃ solution with heterogeneous mixture of MgO and hydroquinone exhibited better absorption performance than that with other combinations. The absorption amounts of NOₓ in 0.15 mol/L Na₂SO₃ 50 mL solution added 0.1% hydroquinone (HQ) with 0.09 mol/L MgO were 2.24 mmol, which improved 5 times than that without additives. In addition, studies on the influence of pH showed that the pH of MgO mixture could be stabilized at 9–10 for a long time, while the pH of Na₂CO₃ mixture decreased faster. Further studies suggested that the hydration of MgO resulted in the solution with MgO keeping high pH. This is also the main reason why the combination of MgO and hydroquinone is superior to the combination of Na₂CO₃ and hydroquinone in desulfurization and denitration performance.
اظهر المزيد [+] اقل [-]Characteristics of dissolved organic matter in surface water and sediment and its ecological indication in a typical mining-affected river—Le’an River, China النص الكامل
2022
Liu, Wenhui | Ma, Teng | Du, Yao | Wu, Xiancang | Chen, Liuzhu | Li, Junqi
Dissolved organic matter (DOM) plays an important role in the cycling and toxicity of heavy metals in aquatic systems. However, most studies have focused only on DOM in either water or sediments. This study aimed to analyze the source, composition, and structural characteristics of DOM in both surface water and bottom sediments of the Le’an River and its major tributaries. In addition, the potential ecological risks of three typical heavy metals (Cu, Pb, and Zn) were quantitatively evaluated based on the characteristics of DOM and in situ data. The results showed that sediment DOM is more aromatic and hydrophobic than surface water DOM. Although humic-like components dominated the DOM pool in both surface water and sediments, their sources were different. Surface water DOM is mainly autochthonous, while sediment DOM is controlled by both autochthonous and allochthonous sources. Risk prediction results based on DOM characteristics show that surface water has a higher potential risk of heavy metal release than sediments. Comprehensively considering the ecological risk of water and sediments, high-risk areas were found to be mainly distributed in the upper and middle reaches of the Le’an River. This distribution is attributable to the developed mining and smelting industries in these areas and consistent with the risk assessment results of measured concentrations of heavy metals. This study established a new technique for predicting the ecological risk of aquatic systems based on the characteristics of DOM in surface water and sediments.
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