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Performance and autopsy of nanofiltration membranes at an oil-field wastewater desalination plant
2019
Zhao, Dongsheng | Su, Chang | Liu, Guicai | Zhu, Youbing | Gu, Zhengyang
In this study, the long-term operational performance of an on-site NF facility at a full-scale oil-field wastewater desalination plant was monitored. The NF facility with poor permeability due to membrane fouling enables efficient multivalent salt removal (rejections of Mg²⁺, Ca²⁺, Fe³⁺, and Al³⁺ were approximately 100%). Moreover, a comparison of the cleaning efficiencies of two on-site cleaning modes indicated that PL-007 cleaning helped to improve the effectiveness of subsequent acid cleaning in the removal of inorganic foulants. Furthermore, a spiral-wound NF membrane module harvested from the plant was unfolded and autopsied. The results showed that both anionic polyacrylamide (APAM) and crude oil were identified as the predominant organic matter on the membrane surface and collectively accounted for a substantial fraction (86.3%) in terms of dry weight. Additionally, dissolved organics with a high molecular weight were prone to accumulation on the membrane surface. Multivalent elements, including Mg, Ca, Al, Fe, and Si, were the primary inorganic species in the fouling layer. Among the inorganic elements, Si occupied a high proportion and existed in the form of SiO₂ in the fouling layer. According to the autopsy results, organic fouling combined with inorganics was responsible for the decline in the flux.
显示更多 [+] 显示较少 [-]The effects of urbanization and globalization on CO2 emissions: evidence from the Sub-Saharan Africa (SSA) countries
2019
Ṣalāḥuddīn, Muḥammadu | Ali, Md Idris | Vink, N. | Gow, Jeff
Ecological modernization theories suggest that it is hard to determine a priori the environmental effects of urbanization, while neoliberal doctrine advocates a positive role of globalization in developing economies especially in terms of reducing poverty and inequality. Yet, the environmental effect of globalization is not unanimous. This study employs second-generation panel regression techniques that account for heterogeneous slope coefficients and cross-sectional dependence to estimate the impacts that urbanization and globalization have on CO₂ emissions for a panel of 44 Sub-Saharan Africa (SSA) countries for the period 1984–2016. Also, a causality test that considers both these issues is performed. The estimated coefficient of urbanization is positive, statistically significant, and highly consistent across different estimation techniques. The magnitude of the coefficient and level of significance are different in different econometric estimations. In most specifications, the estimated coefficient on the globalization variable is statistically insignificant. Urbanization is found to cause emissions. The environmental implications of these results are discussed with a set of policy recommendations for an environmentally better SSA region.
显示更多 [+] 显示较少 [-]Attitudes to climate change, perceptions of disaster risk, and mitigation and adaptation behavior in Yunlin County, Taiwan
2019
Lee, Yung-Jaan | Tung, Chuan-Ming | Lin, Shih-Chien
Issues that are associated with climate change have global importance. Most related studies take a national or regional perspective on the impact of climate change. Taiwan is constrained by its geographical conditions, which increase its vulnerability to climate change, especially in its western coastal areas. The county that is most affected by climate change is Yunlin. In 2013–2014, projects that were sponsored by Taiwan’s government analyzed the relationship among synthesized vulnerability, ecological footprint (EF) and adaptation to climate change and proposed 15 categories of synthesized vulnerability and EF values. This study further examines the relationship between vulnerability and EF values and examines how residents of four townships—Linnei, Sihu, Mailiao, and Huwei—cope with the effects of climate change. This study investigates whether the residents of the four townships vary in their attitudes to climate change, their perceptions of disaster risk, and their behavioral intentions with respect to coping with climate change. The structural equation model (SEM) is used to examine the relationships among attitudes to climate change, perceptions of disaster risk, and the behavioral intentions of residents in townships with various vulnerabilities to climate change. The results that are obtained using the SEM reveal that climate change mitigation/adaptation behavior is affected by attitudes to climate change and perceptions of disaster risk. However, the effects of attitudes and perceptions on mitigation and adaptation that are mediated by place attachment are not statistically significant.
显示更多 [+] 显示较少 [-]Elimination of carcinogenic bromate ions from aqueous environment with 4-vinyl pyridine-g-poly(ethylene terephthalate) fibers
2019
Günay, Kübra | Arslan, Metin | Bozkaya, Ogün | Aluç, Yaşar | Gök, Zehra Gün
In this study, poly(ethylene terephthalate) fibers grafted with 4-vinyl pyridine (PET-g-4VP) was synthesized with using a radical polymerization method and its removal capacity for bromate ions in the aqueous solution was explored. The synthesized graft copolymer was structurally characterized by scanning electron microscopy (SEM) and Fourier transformed infrared spectroscopy (FTIR). The effect of some parameters such as pH, grafting rate, processing time, and ion concentration on bromate removal was examined with batch experiments. The sorptions of bromate onto the PET-g-4VP fibers were both verified with FTIR and X-ray fluorescence analysis (XRF) and the remaining amount of bromate after adsorption process was determined with an ion chromatography (Shimadzu). Moreover, kinetic and isotherm studies were also performed for adsorption of bromate with the grafted fibers. The point of zero charge (pHₚzc) of the PET-g-4VP fibers was found to be 7.5 and the fibers removed maximum amount of bromate from aqueous solution at pH 3. Equilibrium time of adsorption was determined to be 75 min and the adsorption kinetic was found to be pseudo-second-order model. It was observed that the increase in the amount of grafted 4VP onto the PET fibers increased the bromate removal capacity of the fibers; however, when the grafting yield of 4VP was over 80%, the bromate removal ability of the fibers decreased. The maximum bromate removal capacity of the PET-g-4VP was determined to be 183 mg/g when the initial bromate amount was 800 mg/L, treatment time was 75 min, pH of the solution was 3, and 4VP grafting yield was 80%. When the initial bromate concentration was higher than 800 mg/L, the removal rate of the PET-g-4VP fibers was not changed. In addition, bromate ion adsorption data indicated compliance with the Freundlich isotherm. The adsorbent fibers obtained by this study may be promising candidates for the removal of bromate ions from the aqueous media.
显示更多 [+] 显示较少 [-]A two decades study on ozone variability and trend over the main urban areas of the São Paulo state, Brazil
2019
Schuch, Daniel | de Freitas, Edmilson Dias | Espinosa, Sergio Ibarra | Martins, Leila Droprinchinski | Carvalho, Vanessa Silveira Barreto | Ramin, Bruna Ferreira | Silva, Jayne Sousa | Martins, Jorge Alberto | de Fatima Andrade, Maria
In this paper, we analyze the variability of the ozone concentration over São Paulo Macrometropolis, as well the factors, which determined the tendency observed in the last two decades. Time series of hourly ozone concentrations measured at 16 automated stations from an air quality network from 1996 to 2017 were analyzed. The temporal variability of ozone concentrations exhibits well-defined daily and seasonal patterns. Ozone presents a significant positive correlation between the number of cases (thresholds of 100–160 μg m⁻³) and the fuel sales of gasohol and diesel. The ozone concentrations do not exhibit significant long-term trends, but some sites present positive trends that occurs in sites in the proximity of busy roads and negative trends that occurs in sites located in residential areas or next to trees. The effect of atmospheric process of transport and ozone formation was analyzed using a quantile regression model (QRM). This statistical model can deal with the nonlinearities that appear in the relationship of ozone and other variables and is applicable to time series with non-normal distribution. The resulting model explains 0.76% of the ozone concentration variability (with global coefficient of determination R¹ = 0.76) providing a better representation than an ordinary least square regression model (with coefficient of determination R² = 0.52); the effect of radiation and temperature are the most critical in determining the highest ozone quantiles.
显示更多 [+] 显示较少 [-]Iron and manganese present in underground water promote biochemical, genotoxic, and behavioral alterations in zebrafish (Danio rerio)
2019
Marins, Katiuska | Lazzarotto, Luan Marcos Valentini | Boschetti, Gabrielle | Bertoncello, Kanandra Taisa | Sachett, Adrieli | Schindler, Monica Santin Zanatta | Chitolina, Rafael | Regginato, Alissara | Zanatta, Ana Paula | Siebel, Anna Maria | Magro, Jacir Dal | Zanatta, Leila
Iron (Fe) and manganese (Mn) are metals commonly found at high concentrations in underground water. These metals are essential for the good functioning of living organisms, but high concentrations lead to imbalance, potentiating the appearance of pathologies. This study aimed to evaluate the effect of exposure to naturally occurring metals in groundwater, using zebrafish (Danio rerio) as an experimental model. Thus, zebrafish were exposed to Fe (0.8 and 1.3 mg/L), Mn (0.2 and 0.4 mg/L), and groundwater collected from deep tube wells with Fe and Mn (Fe 0.8/Mn 0.2 mg/L and Fe 1.3/Mn 0.4 mg/L) for 30 days. Bioaccumulation of these metals has been demonstrated in the livers and muscles of zebrafish. Acetylcholinesterase activity changed only in zebrafish muscles in all groups. Sulfhydryl levels changed mainly in the group Mn 0.4. SOD/CAT ratio decreased in the groups Fe 0.8 and 1.3, Mn 0.4, and Fe 0.8/Mn 0.4. An increase in the frequency of micronucleus in all groups was shown as a consequence of these changes. Behavioral parameters (time and distance traveled, mean speed, turn angle, latency, and number of crossings between compartments) have also changed, mainly in the groups Fe 1.3, Mn 0.4, and Fe 1.3/Mn 0.4. Therefore, long-term exposure to Fe and Mn, even at not so high concentrations, may cause biochemical, genotoxic, and behavioral changes in zebrafish.
显示更多 [+] 显示较少 [-]Quantitative proteomic analysis of tomato genotypes with differential cadmium tolerance
2019
Borges, Karina Lima Reis | Salvato, Fernanda | Loziuk, Philip L. | Muddiman, David C. | Azevedo, Ricardo Antunes
This is a report on comprehensive characterization of cadmium (Cd)-exposed root proteomes in tomato using label-free quantitative proteomic approach. Two genotypes differing in Cd tolerance, Pusa Ruby (Cd-tolerant) and Calabash Rouge (Cd-sensitive), were exposed during 4 days to assess the Cd-induced effects on root proteome. The overall changes in both genotypes in terms of differentially accumulated proteins (DAPs) were mainly associated to cell wall, redox, and stress responses. The proteome of the sensitive genotype was more responsive to Cd excess, once it presented higher number of DAPs. Contrasting protein accumulation in cellular component was observed: Cd-sensitive enhanced intracellular components, while the Cd-tolerant increased proteins of extracellular and envelope regions. Protective and regulatory mechanisms were different between genotypes, once the tolerant showed alterations of various protein groups that lead to a more efficient system to cope with Cd challenge. These findings could shed some light on the molecular basis underlying the Cd stress response in tomato, providing fundamental insights for the development of Cd-safe cultivars. Graphical abstract
显示更多 [+] 显示较少 [-]The dirty energy dilemma via financial development and economic globalization in Pakistan: new evidence from asymmetric dynamic effects
2019
T̤āriq, Muḥammad | Xu, Yingzhi | Muhammad, Faqeer | Alam, Khalid Mehmood
Energy strategy has been an essential strand in the view of economists in achieving rapid development process of any country. The recent wave of globalization exerts pressure on energy consumption via financial development which ultimately vindicates economic growth. This paper has covered a period of 1976–2016 using annual data for the empirical analysis and constructed a growth equation as the main equation and the energy consumption equation as a channel equation. The empirical study has been undertaken by performing ARDL and nonlinear autoregressive distributed lag models (NARDL). The bound test result declares a long-run association in both equations. Consequently, energy consumption and economic globalization have significantly enhanced economic growth in the long run. Whereas, financial development index has no influence on the economic growth of Pakistan. The results of channel equation suggested that due to growing the price of crude oil, the energy consumption is reduced in the long run. The increasing imports of energy products and increasing urbanization are conducive for energy consumption in Pakistan. By NARDL model, our empirical findings provide robust support for the existence of asymmetric co-integration linking among underlying variables of the study.
显示更多 [+] 显示较少 [-]Regional convergence of energy-environmental efficiency: from the perspective of environmental constraints
2019
Sheng, Xin | Peng, Benhong | Elahi, Ehsan | Wei, Guo
This paper conducts a convergence analysis on the energy-environmental efficiency to explore the differences between regions that reflect the implementation effect of the policies on energy-saving and emission reduction. Particularly, for the Yangtze River urban agglomeration, additive model (AM model) is applied to calculate the energy-environmental efficiency, and the convergence model is employed to analyze the heterogeneity and spatial evolution of energy-environmental efficiency. From the results, the energy-environmental efficiency for Suzhou is at a good level; the figures for Wuxi, Yangzhou, and Nantong maintain at medium level; for Zhenjiang, qualified level; and for Nanjing, Changzhou, and Taizhou, poor level. The energy-environmental efficiency of the whole Yangtze River urban agglomeration displays a downward trend of fluctuations. While Nantong reveals a divergent energy-environmental efficiency, Zhenjiang, Changzhou, Wuxi, Yangzhou, and Nanjing Cities generally show a trend of convergence. It was also recognized that the energy-environmental efficiency is gradually decreasing from Southeast to North to Southwest regions. In the past decade, the north region of Yangtze River yielded a divergent development trend, while the southeast and southwest regions appear to have a convergent development trend. In the future, the urban agglomeration needs to promote the coordinated development of the economy and the energy environment, impel the optimization and upgrading of the industrial structure, narrow the regional gap, and adjust the energy consumption habits.
显示更多 [+] 显示较少 [-]Attitudes and behaviour towards construction waste minimisation: a comparative analysis between China and the USA
2019
Liu, Jingkuang | Gong, Enqin | Wang, Dong | Lai, XiaoHong | Zhu, Jian
With the spread of the concept of sustainable development, people have gained awareness about the problem of massive illegal dumping of construction waste. In this research, a questionnaire survey was carried out in the USA and China. The results indicated the following. (1) Workers in both the countries had positive minimisation attitudes, and the attitude of Chinese construction workers was not significantly different from that of American construction workers. Furthermore, their average values were 3.9 and 4.07, respectively. (2) Business owners had a poor understanding of the obligations that should be fulfilled by contractors and construction workers, which greatly reduced (a) construction workers’ and contractors’ motivation to implement waste minimisation management and (b) the benefit-driven effect. (3) In terms of perceived behavioural control, Chinese construction workers had poorer minimisation technologies and knowledge than American construction workers, and it was very difficult for them to implement construction waste minimisation. The research conclusions and relevant suggestions may be used to improve the construction waste minimisation behaviour and awareness of Chinese people and promote China’s construction waste minimisation management.
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