خيارات البحث
النتائج 2221 - 2230 من 4,896
Energy Efficiency and Energy Conservation in China’s Transportation Industry: A Three-stage Data Envelopment Analysis Approach
2019
Cheng Zhang and Zhaoyu Yu
China’s transportation industry holds high energy consumption. The energy consumption of China’s transportation industry climbs up gradually with progress in urbanization and growing volume of passenger and freight traffic, which causes heavy environmental pollution. Improving energy efficiency is an important factor and management goal that influences the sustainable development of the transportation industry. In this study, an energy efficiency evaluation system of transportation industry was initially constructed, and the three-stage data envelopment analysis (DEA) model was adopted to estimate the energy efficiency of China’s transportation industry during 2001-2016. Subsequently, environmental variables were introduced to further perfect the calculation results. Results demonstrate that the technical efficiency (TE) of China’s transportation industry is 1 in 6 years during the study period in the traditional DEA model, reaching the technological frontier level. TE still has a large potential for improvement. The input redundancy of energy efficiency in China’s transportation industry may increase as per capita gross domestic product increases. However, such input can be effectively decreased by increasing the total export-import volume and total retail sales of consumer goods. After eliminating environmental and random factors, the low energy efficiency of China’s transportation industry is mainly caused by scale inefficiency. Conclusions in this study can provide theoretical references to understand and improve the energy efficiency of the transportation industry and thus formulate effective transportation energy and environmental policies.
اظهر المزيد [+] اقل [-]Review of the Sedimentological and Geochemical Approaches for Environmental Assessment of River Sadong, Samarahan-Asajaya District Sarawak, Malaysia
2019
Omolayo Ajoke Omorinoye, Zaini Bin Assim, Ismail Bin Jusoh, Naseer Inuwa Durumin Iya and Isaac John Umaru
This paper presents an overview of the implication of geomorphology and sedimentology on the chemical characteristics of sediments of River Sadong, Malaysia. There is limited published work on the effect of topography, climate, soil and geology on the sediments lying in the River Sadong. Studies have been undertaken around Kota Samarahan and Asajaya areas whereby some heavy metal constituents and their environmental effects were determined. The study entails the description of the depositional processes alongside with physical and geochemical changes, without neglecting natural and anthropogenic effects.
اظهر المزيد [+] اقل [-]Variations of Environmental Isotopes in Precipitation and Surface Water in Plain Area Influenced by Summer Monsoon: A Case Study in Jinjiang River Basin, Chengdu, China
2019
Chengcheng Xia, Jie Mei, Wen Liu, Jing Zhou and Guodong Liu
Monsoon is a typical wind system, which influences a quarter of continental area on the earth and is closely bound up with the life of one half of the earth’s population. Therefore, it is important to explore the information on monsoon activities. In the present study, samples of precipitation and surface water collected in the summer of 2018 were analysed to reveal the variation of stable isotopes influenced by summer monsoon and its relationship with the sources of water vapour. The temporal variation of stable isotopes in precipitation is great during the monsoon period, which is primarily the result of the varying proportions of water vapour from continental and oceanic sources. The heavy isotopes in precipitation grew gradually as the proportion of ocean-source water vapour increased from May to August. The meteorological parameters of temperature and precipitation amount are not the main factors that influence the isotopic composition in precipitation, for the determination coefficient (R2 value) is low. The isotopic characteristics of river water are similar to those of precipitation, indicating that the rivers are mainly recharged by precipitation. The temporal-spatial variations of isotopes surface water are complex for the joint influence of the distribution of isotopes in precipitation, isotopic compositions of the river source, rainfall amount and evaporation, which can be considered as the indirect effects of monsoon activities.
اظهر المزيد [+] اقل [-]Preparation, Characterization and Adsorption Capacity of Bauxite-Carbon Nanotube Composite
2019
Suha Sahib Abd and Ahmed Mohammed Abbas
Iraqi bauxite clay was modified by using multiwall carbon nanotube (MWCNTs) as a modifying agent. The characterization of bauxite and bauxite/carbon nanotube was accomplished by using the Fourier transform infrared spectroscopy, scanning electron microscopy, atomic forces microscopy and X-Ray diffraction techniques. Uses the bauxite and bauxite/carbon nanotube composite for methyl green dye adsorption were achieved in a batch system. The adsorption equilibrium was attained at 60 and 45 min and adsorption efficiency reached maximum of 22 and 31% for bauxite and bauxite/carbon nanotube composite respectively, at an adsorbent dose of 0.01 g and initial dye concentration of 16 mg/L. Relying on the above shows that bauxite/carbon nanotube is a suitable adsorbent for the adsorption of methyl green dye, better than the bauxite clay.
اظهر المزيد [+] اقل [-]Synergetic Effects of Zero-valent Iron and Morganella morganii on the Removal of Cr(VI) from Wastewater
2019
Jiamin Huang, Yizi Ye, Zheng Fu, Wen Jing Dun, Yangyang Wang, Linshan Fang, Suhui Ye, Xiaoying Ye, Jiaojun Jin and Qingyuan Hu
Zero-valent iron permeable reactive barrier (ZVI-PRB) has attracted great attention for its high efficiency and low cost in the in-site remediation process. However, passivating oxide layers are usually yielded and covered on the surface of ZVI, which shorten the service life of PRB. In this study, Morganella morganii subsp was used to hydrolyse the passivating oxide layers on ZVI. The hydrolysing condition was optimized. The highest Cr(VI) removal efficiency was achieved with glucose of 4 g/L, yeast powder of 6 g/L and pH = 7. With Morganella morganii subsp, the maximum removal quality of ZVI was increased from 19.96 mg/g to 24.35 mg/g, indicating Morganella morganii subsp could improve the reduction ability of ZVI. SEM-EDS analysis also showed that M. morganii subsp could promote the surface corrosion of ZVI and adsorb Cr simultaneously.
اظهر المزيد [+] اقل [-]Biomass and Soil Organic Carbon Stocks Under Cedrus deodara Forests in Mandi District of Himachal Pradesh
2019
Manoj Thakur and R. K. Verma
The estimation of carbon sequestration in forest ecosystem is necessary to plan for mitigating the impacts of climate change. The present study was conducted in the Cedrus deodara (CD) forests of Mandi district in Himachal Pradesh to estimate the biomass and soil organic carbon stock at various sites of the study area. Overall, 18 plots of 0.1 ha were laid at six sites randomly in the year 2014-15. In CD forest, the mean stem density was 354 trees/ha and the mean basal area and mean volume were 62.28 m2/ha and 719.71 m3/ha respectively. The mean carbon stock for tree aboveground, tree belowground, understorey and litter were 189.93 ton/ha, 37.99 ton/ha, 1.71 ton/ha and 0.72 ton/ha respectively. The soil organic carbon percentages varied from 1.98-2.83%, 1.72-2.11% and 1.56-1.74% at soil depth of 0-15cm, 15-30cm and 30-45cm respectively, and the soil organic carbon stocks ranged from 24.41-32.22 ton/ha, 21.59-29.03 ton/ha and 19.17-26.78 ton/ha at soil depths of 0-15cm, 15-30cm and 30-45cm respectively. The total mean soil organic carbon (SOC) stock up to a depth of 0-45cm was found to be 76.16 ton/ha. The organic carbon percentage showed a decreasing trend with increasing soil depth.
اظهر المزيد [+] اقل [-]Study on the Influence of Land Use Patterns on the Comprehensive Harnessing Effects of Soil and Water Erosion
2019
Zhaoya Chen, Lijun Ma, Fengyu Guo, Xiangling Ma and Yu Chu
Comprehensive harnessing of soil and water erosion can change the regional surface environment, improve ecological conditions, and promote regional social and economic development, which can also achieve good ecological, social, and economic benefits for the purpose of preventing and controlling soil erosion. Scientific evaluation of soil erosion comprehensive harnessing benefits is presented, and analysis of influencing factors is adopted, which is an important basis for further understanding of work effectiveness and optimization of governance measures. The research selects Taihang Mountain Area of Hebei Province as the research area. This paper evaluates the comprehensive treatment benefits of 16 typical small watersheds by multi-level fuzzy evaluation method, and uses the exponential, linear, logarithmic, power function and polynomial as the model. The correlation between land use type area and comprehensive treatment benefit was studied, and the corresponding improvement of management efficiency has been proposed in order to provide a reference for optimizing the comprehensive management mode of small watersheds in Taihang Mountain area and improving the efficiency of comprehensive management.
اظهر المزيد [+] اقل [-]Urban and Rural Residents’ Willingness to Pay for Desertification Prevention and Control and its Influencing Factors
2019
Weipeng Chao, Changjiang Zhang and Pengcheng Wang
The prevention and control of desertification cannot be separated from the active participation of local urban and rural residents. However, only a few studies on the difference in urban and rural residents’ willingness to pay for the prevention and control of desertification and its influencing factors are available. To explore the differences in urban and rural residents’ willingness to pay for desertification prevention and control, the status quo and influencing factors of willingness to pay for desertification prevention and control among urban and rural residents were analysed by linear regression analysis method and the micro-survey data of 300 urban and rural residents in the middle and lower reaches of the Tarim River in Xinjiang, China. Results show that urban and rural residents’ willingness to pay for desertification prevention and control is affected by education level, ecological environment concern, ecological environment protection needs, attention to desertification, and cognition of desertification control effect. Several preventive measures were provided with respect to enhancing residents’ awareness of desertification prevention and control, raising residents’ income and push forward systematic innovation.
اظهر المزيد [+] اقل [-]Study on the Effect of Water, Fertilizer and Biochar Interaction on N2O Emission Reduction in Paddy Fields of Northeast China
2019
Yanyu Lin, Shujuan Yi, Zhongxue Zhang, Mengxue Wang and Tangzhe Nie
Taking the black soil of northeastern cold land as the research object, this paper adopts the three-factor quadratic saturation D311 optimal design scheme, uses static black box-gas chromatography to analyse the irrigation season, nitrogen fertilizer and straw biochar to the impact of greenhouse gas emissions for N2O growing season in the northeast cold paddy field. This paper also studies the optimal water and fertilizer application scheme for N2O control. The results show that the effects of three factors on N2O emissions are as follows: nitrogen fertilizer > biochar > water. The irrigation and biochar have an inhibitory effect on N2O emissions, while nitrogen fertilizer has a promoting effect on N2O emissions. The performance is as follows: water + nitrogen fertilizer can promote the emission of N2O; water + biochar can inhibit the emission of N2O; nitrogen fertilizer + biochar can promote the emission of N2O. Combined with the yield, the integrated water and biochar optimization schemes, when controlling the increase of N2O growth season in paddy fields to not exceed 10% are as follows: The amount of irrigation is 4252~5531 kg/hm2; the nitrogen application rate is 103.30~117.35 kg/hm2; and the amount of biochar is 15.12~24.42 t/hm2.
اظهر المزيد [+] اقل [-]Degradation of Dye C.I. Reactive Red 15 in Aqueous Solution by Kaolinite Supported Zero Valent Iron
2019
Sheng Fang, Ningcan Yang, Muqing Qiu and Chengcai Huang
Dyes are important source of water pollution and their degradation products may be carcinogens and toxic to mammals. For evaluation of oxidative degradation of dye wastewater, the kaolinite supported zero valent iron were synthesized. The surface morphology of kaolinite and kaolinite supported zero valent iron were observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The degradation of dye C.I. Reactive Red 15 in aqueous solution by kaolinite supported zero valent iron was investigated in details. The effects of the dosage of kaolinite supported zero valent iron, pH in solution, reaction time and the initial dye concentration on the degradation were studied. The results showed that the pH value, the dosage of kaolinite supported zero valent iron and the initial dye concentration had an important impact on dye degradation. Under these conditions, such as 80 mg/L dye C.I. Reactive Red 15, 20 min of reaction time, 0.5 g kaolinite supported zero valent iron particles, pH value of 2.0, temperature of 308 K and 120 rpm respectively, the degradation rate of dye C.I. Reactive Red 15 reached 82.3%.
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