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Результаты 3201-3210 из 4,924
Revealing long- and short-run empirical interactions among foreign direct investment, renewable power generation, and CO2 emissions in China
2019
Ahmad, Munir | Zhao, Zhen-Yu | Rehman, Abdul | Shahzād, Muḥammad | Li, Heng
This work systematically examines the empirical interactions among foreign direct investment (FDI), renewable power generation (RPG), hydropower generation (HPG), non-hydropower generation (NHPG), and CO₂ emissions in the long run and short run. To test the existence of long-run equilibrium association among those variables, Bayer-Hanck combined cointegration and autoregressive distributed lag (ARDL) model have been employed on time series of China for the period 1991–2017. The vector error correction model-based short-run impacts among the variables of interest are also estimated. Besides, Toda-Yamamoto causality and Granger causality are employed to confirm the direction of causal links. The existence of a long-run equilibrium relationship is revealed in case of all types of specification. The expansion of both FDI and CO₂ emissions boosted RPG, HPG, and NHPG in the short run and long run, with greater intensity of impacts in the long run. To reflect comparisons, it is found that the renewables generation driving the impact of CO₂ emissions and FDI on NHPG is greater than RPG, which further exceeds HPG. In turn, the RPG, HPG, and NHPG mitigated CO₂ emissions both in the long run and short run, with stronger impacts in the long run. Moreover, the CO₂ emissions inhibition impact of HPG dominated NHPG, which further exceeded that of RPG. The FDI boosted CO₂ emissions in a way that the long-run pollution haven impact is revealed to be powerful than that of the short run. A unidirectional causality has been observed running from FDI to CO₂ emissions, RPG, HPG, and NHPG. A bidirectional causality is found operative between CO₂ emissions and RPG/HPG/NHPG. Interestingly, the long-run and short-run impacts remained homogeneous in terms of directionality. Nevertheless, strict heterogeneity is observed in terms of the degree of impacts. Based on empirics, both long-term and short-term policies on FDI, renewables generation, and CO₂ emissions are vital for decision-makers in China. Graphical abstract
Показать больше [+] Меньше [-]Gonadal, body color, and genotoxic alterations in Lithobates catesbeianus tadpoles exposed to nonylphenol
2019
Scaia, María Florencia | de Gregorio, Lara Salgueiro | Franco-Belussi, Lilian | Succi-Domingues, Maysa | de Oliveira, Classius
Endocrine disrupting chemicals are one of the most important factors contributing to worldwide amphibian decline. The 4-nonylphenol (NP) is a degradation product of several compounds, such as detergents and pesticides, affecting the aquatic environment. Here, we test whether treatment with NP has an effect on developing ovarian tissue, nuclear abnormalities in erythrocytes, and body darkness in pre-metamorphic tadpoles of the bullfrog Lithobates catesbeianus. Tadpoles were exposed for 14 days to three different concentrations of NP (1, 10, and 100 μg/L) besides the control group, which was maintained only with water. After determining body coloration, animals were euthanized and gonads and blood were collected and processed for histology and genotoxic analysis. Even though most animals were females, intersex tadpoles were observed in control and treated groups and there were no males in any group. The highest concentration of NP showed an increase in atretic oocytes, but the area corresponding to somatic compartment and early and late germ cells were not affected. Furthermore, all treated groups presented higher amount of nuclear abnormalities in erythrocytes and body darkening when compared with the control group. These results suggest that NP causes genetic damage and morphological alterations in L. catesbeianus tadpoles by disrupting oogenesis, inducing genotoxicity and increasing body coloration. Its effects on gonadal development could cause future impairments in reproduction, while its deleterious effects on genotoxicity and body pigmentation could be used as a biomarker of effect to this compound.
Показать больше [+] Меньше [-]Use of Salvinia sp on the adsorption of hexavalent chromium
2019
Oliveira, Jessika Cabral G. | de Moraes Ferreira, Rachel | Stapelfeldt, Danielle M. A.
The remotion of hexavalent chromium in the form of chromate in aqueous solution was done using the aquatic plant Salvinia sp as biosorbent. The chemical modification of the Salvinia surface was performed by organosolv adapted method. The untreated Salvinia and the modified were characterized by infrared spectroscopy, Boehm titration, scanning electron microscopy, energy dispersive system, point of zero charge, surface area analysis, and porosity. Batch adsorption experiments were performed to observe the effects of pH, contact time, initial concentration, and temperature on the metal removal process. The characterization results show the chemistry modifically changed the modified Salvinia structure compared with untreated Salvinia. The adsorption test results showed the maximum adsorption capacity of 26.03 mg g⁻¹. The kinetic equilibrium was reached in about 3 h, and the better temperature and pH were 298 K and 7, respectively. The adsorption and kinetic models were Freundlich and pseud-second order, respectively. This study showed the Salvinia sp after the chemical treatment can be used with biosorbent for hexavalent chromate in the form of chromate, being a natural material with low cost and plentiful in the environment.
Показать больше [+] Меньше [-]The impact of particulate matter on allergy risk among adults: integrated exposure assessment
2019
Dėdelė, Audrius | Miškinytė, Auksė | Gražulevičienė, Regina
Exposure assessment is an important part in environmental epidemiology for determining the associations of environmental factors with health effects. One of the greatest challenges for personal exposure assessment is associated with peoples’ mobility during the day and spatial and temporal dynamics of air pollution. In this study, the impact of PM₁₀ (particulate matter less than 10 μm) on allergy risk among adults was assessed using objective methods of exposure assessment. The primary objective of the present study was to estimate personal exposure to PM₁₀ based on individual daily movement patterns. Significant differences between the concentration of PM₁₀ in different microenvironments (MEs) and personal exposure to PM₁₀ were determined. Home exposure accounted for the largest part of PM₁₀ exposure. Thirty-five percent of PM₁₀ exposure was received in other non-home MEs. Allergy risk increased significantly with increasing exposure to PM₁₀. Adults exposed to the highest levels of PM₁₀ exposure had a twice-higher risk of allergies than adults exposed to the lowest levels of PM₁₀ exposure. The study results have practical relevance for exposure assessment to environmental factors and its impact on health effects.
Показать больше [+] Меньше [-]Re-visiting environmental Kuznets curve: role of scale, composite, and technology factors in OECD countries
2019
Sohag, Kazi | Kalugina, Olga | Samargandi, Nahla
This study assesses environmental Kuznets curve (EKC) hypothesis corroborating the role of scale, composite, and technology effects in OECD countries. To this end, we analyze the panel time series data from 1980 to 2017 using cross-sectional-autoregressive distributed lags (CS-ARDL). We document that economic growth and carbon emissions follow a U-shaped relationship, contrary to the EKC hypothesis, which our analysis attributes to the substantial contributions of the industrial, manufacturing, and service sectors to GDP. Technological progress has a somewhat marginal impact in reducing carbon emissions through energy efficiency but is unable to validate the existence of EKC hypothesis.
Показать больше [+] Меньше [-]Using crop modeling to evaluate the impacts of climate change on wheat in southeastern turkey
2019
Vanli, Ömer | Ustundag, Burak Berk | Ahmad, Ishfaq | Hernandez-Ochoa, Ixchel M. | Hoogenboom, Gerrit
The extreme temperatures and uneven distribution of rainfall associated with climate change are expected to affect agricultural productivity and food security. A study was conducted to evaluate the impact of climate change on wheat in southeastern regions of Turkey. The CERES-wheat crop simulation model was calibrated and evaluated with data from eight surveyed farms. The four farms were used for calibration and four for evaluation. Climate change scenarios were developed for the middle (2036–2065) and late 21st century (2066–2095) under representative concentration pathways (RCPs 4.5 and 8.5) for study sites in Islahiye and Nurdagi. Model calibration results showed a good agreement between observed and simulated yield with only a 1 to 11% range of error. The model evaluation results showed good fit between observed and simulated values of all parameters with % error ranged from 0.51 to 13.3%. Future climate change projections showed that maximum temperature (Tmax) will increase between 1.6 °C (RCP4.5) and 2.3 °C (RCP8.5), while minimum temperature (Tmin) will increase between 1.0 °C (RCP4.5) and 1.5 °C (RCP8.5) for mid-century. At the end of the century, Tmax is projected to increase from 2 °C (RCP4.5) to 4 °C (RCP8.5) and Tmin from 1.3 °C (RCP4.5) to 3.1 °C (RCP8.5). Climate change impacts results showed that future rise in temperature will reduce wheat yield by 16.3% in mid-century and 16.8% at the end of the century at Islahiye and for Nurdagi, while 13.0% in mid and 14.4% end of the century. The use of climate and crop modeling technique provides useful information in evaluating the climate change impacts and may assist stakeholders to make decisions to overcome the negative impacts in the near and long term.
Показать больше [+] Меньше [-]Adsorption of a textile dye onto piaçava fibers: kinetic, equilibrium, thermodynamics, and application in simulated effluents
2019
Marques, Bianca Silva | Frantz, Tuanny Santos | Sant’Anna Cadaval Junior, Tito Roberto | de Almeida Pinto, Luiz Antonio | Dotto, Guilherme Luiz
This research was conducted to evaluate the methylene blue dye adsorption by piaçava fibers. The effects of adsorbent amount, pH, kinetics, equilibrium, and thermodynamics were analyzed, as well as the adsorbent performance in the treatment of synthetic textile effluents. The adsorbent characterization was also performed. Experimental kinetic data were fitted with pseudo-first-order, pseudo-second-order, and Elovich models. The equilibrium tests were done at 298, 308, and 318 K, and the models of Freundlich, Langmuir, Redlich–Peterson, and Sips were used. The adsorption was favored using 0.025 g of adsorbent, pH 10, and 318 K. The Elovich model provided better fit to kinetic data. The equilibrium experimental points were well represented by the Sips model. The maximum experimental adsorption capacity of methylene blue dye was 427.3 mg g⁻¹. It was verified a spontaneous, favorable, and endothermic adsorption. Piaçava fiber was a promising low-cost material to be used for color removal in effluents containing methylene blue.
Показать больше [+] Меньше [-]Investigation of toxic effects of amorphous SiO2 nanoparticles on motility and oxidative stress markers in rainbow trout sperm cells
2019
Özgür, Mustafa Erkan | Ulu, Ahmet | Özcan, İmren | Balcioglu, Sevgi | Ateş, Burhan | Köytepe, Süleyman
In this study, we investigated the effects of SiO₂ nanoparticles (SiO₂-NPs) (1, 10, 25, 50, and 100 mg/L) for 24 h in vitro on the motility parameters and oxidative stress markers such as total glutathione (TGSH), catalase (CAT), and malondialdehyde (MDA) of rainbow trout, Oncorhynchus mykiss sperm cells. Therefore, SiO₂-NPs were synthesized with sol-gel reaction from tetraethoxy orthosilicate (TEOS). The prepared nanoparticle structures were characterized for chemical structure, morphology and thermal behavior employing Fourier transform infrared spectroscopy, X-ray spectroscopy, scanning electron micrograph, and thermal analysis (DTA/TGA/DSC) techniques. After exposure, there was statistically significant (p < 0.05) decreases in velocities of sperm cells. CAT activity significantly (p < 0.05) decreased by 9.6% in sperm cell treated with 100 mg/L. In addition, MDA level significantly increased by 70.4% and 77.5% in sperm cell treated with 50 and 100 mg/L SiO₂-NPs, respectively (p < 0.05). These results showed that SiO₂-NPs may have toxic effect on rainbow trout sperm cells in 50 mg/L and more.
Показать больше [+] Меньше [-]Changes of vegetation carbon sequestration in the tableland of Loess Plateau and its influencing factors
2019
Zhang, Jie | Liu, Mengyun | Zhang, Mengmeng | Yang, Jinghan | Cao, Runshan | Malhi, Sukhdev S.
The variations of vegetation carbon sequestration have become a gauge for evaluating the ecological effect of vegetation restoration. In this study, the spatiotemporal patterns of the net ecosystem production (NEP) were simulated using an improved CASA model and GSMSR model. It showed that the NEP markedly increased in the tableland of Loess Plateau during 2003–2012, with an annual average growth of 3.65 g C·m⁻² a⁻¹. The mixed broadleaf-conifer forest ranked first (127.23 g C·m⁻² a⁻¹) while the bare land and sparse vegetation presented the lowest carbon sequestration (14.64 g C·m⁻² a⁻¹). The NEP manifested a significantly uneven overall spatial distribution: high in the southwest and low in the northeast. The spatial variations of NEP resulted from the combined effects of geographic position, terrain, meteorology, and soil and vegetation, respectively. Quantitative isolation revealed that the most dominant factor of vegetation carbon sequestration was soil and vegetation, while terrain exerted insignificant impacts on the NEP.
Показать больше [+] Меньше [-]Highly porous carboxylated activated carbon from jute stick for removal of Pb2+ from aqueous solution
2019
Ājija, Moḥ. Ābadula | Chowdhury, Imran Rahman | Jafar Mazumder, Mohammad Abu | Chowdhury, Shakhawat
Drinking water is a potential source of human exposure to lead (Pb²⁺), which can induce several health effects upon exposure to low dose for a long period. In particular, the children and young populations are the vulnerable groups. Removal of Pb²⁺ from drinking water using an inexpensive adsorbent is a challenge. In this research, activated carbon adsorbent was developed using jute stick, an agricultural by-product. Following carboxylic acid functionalization, the jute stick activated carbon (JSAC) was applied for Pb²⁺ removal from aqueous solution. The carboxylated JSAC (JSAC-COO⁻) was characterized using several techniques. The surface area of the JSAC-COO⁻ was 615.3 m²/g. The JSAC-COO⁻ was tested for variable concentrations of Pb²⁺ (10 and 25 mg/L) at different pH (4.0 and 7.0), temperature (15 °C and 27 °C), and contact periods (1, 5, 10, 15, 30, and 60 min). Up to 99.8% removal of Pb²⁺ was achieved for these concentrations of Pb²⁺ within 15 min of contact time. The adsorption process followed standard kinetics, and the adsorption capacity was > 25.0 mg Pb²⁺/g of JSAC-COO⁻. The JSAC-COO⁻ can be used for fast and easy removal of Pb²⁺ from aqueous solution, which has the potential for domestic and industrial applications.
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