خيارات البحث
النتائج 2501 - 2510 من 4,936
Effluent from Citrus Industry: Toxic Parameters of Orange Vinasse النص الكامل
2019
Garcia, Camila Fernandes H. | de Souza, Raphael B. | de Souza, Cleiton Pereira | Fontanetti, Carmem Silvia
Brazil is one of the greatest producers of orange and its orange juice processing industry produces large volumes of solid and liquid waste daily. As an efficient use of the residues from citrus industry, production of bioethanol is highlighted. However, the generation of bioethanol produces a liquid effluent as a by-product, known as vinasse. The objective of this study was to evaluate the toxicity of an effluent from citrus industries, orange vinasse, when applied to soil using Allium cepa seeds. The evaluation was performed by means of germination, root growth, and genotoxic and mutagenic parameters. The EC₅₀ (effectiveness concentration) and ½ EC₅₀, defined in the germination test, were used for genotoxicity tests. Toxicity was observed in dilutions above 40%, which was responsible for reducing the germination speed index. Genotoxicity was observed only using the EC₅₀ and mutagenicity was not detected. According to the results, orange vinasse showed toxicity similar to the sugar cane vinasse, so caution is suggested in the disposal of this effluent into the environment.
اظهر المزيد [+] اقل [-]Estimation of real-world traffic emissions for CO, SO2, and NO2 through measurements in urban tunnels in Tehran, Iran النص الكامل
2019
Heydarizadeh, Ali | Kahforoushan, Davood
Mobile sources are considered to be one of the most important sources of air pollution among which are motor vehicles, recognized as the major contributor of air pollutants in urban areas. To determine the emissions for CO, SO₂, and NO₂ from motor vehicles as part of the attempt to realize the extent of traffic air pollution, measurements were carried out in two heavily traversed traffic tunnels in Tehran metropolitan area. The concentrations of pollutants and metrological and traffic data were collected through intensive measurements from September 27 to October 17, 2016. Resalat Tunnel fleet was composed of about 10% diesel-fueled vehicles and 90% non-diesel-fueled vehicles while throughout the entire duration of our campaign, only non-diesel-fueled vehicles traversed Niayesh Tunnel. Under an average traffic speed of 43 km h⁻¹, emission factors from Resalat Tunnel campaign were measured to be (6.59 ± 2.69)E+3, (1.42 ± 0.84)E+2, and 6.80 ± 4.99 mg km⁻¹ for CO, SO₂, and NO₂, respectively. These values were respectively 11% higher, 22% lower, and 40% higher than those from Niayesh Tunnel measurements which were recorded at a traffic speed of 30 km h⁻¹. Current results indicate that the vehicular emissions in certain countries, especially the developing ones and in this case, Iran, are quite different from those measured in developed countries and that the high emission levels of SO₂ in Iran are associated with the high sulfur content of the gasoline.
اظهر المزيد [+] اقل [-]Analysis of the total factor energy efficiency and its influencing factors of the Belt and Road key regions in China النص الكامل
2019
Yang, Zhongshan | Wei, Xiaoxue
Energy cooperation has been emphasized strongly in the Belt and Road (B&R) initiative. Therefore, the energy efficiency of China has attracted much attention from experts. However, relevant studies are still insufficient. This paper analyzes the total factor energy efficiency (TFEE) and its influencing factors of 17 B&R key regions from 2005 to 2015. We use the ratio of target energy input and actual energy input to calculate the regional TFEE under environmental constraints. The Malmquist index and the Tobit model are applied to investigate the internal and external influences of TFEE. Measurement analysis shows that the TFEE of the B&R key regions has not improved in recent years and it is unbalanced during the study period. Regions in the east area have the highest TFEE; regions in the west area have the second high TFEE; and regions in the north area have the lowest TFEE. Regression analysis shows that for the B&R key regions, technical changes, coal consumption, research and development, and environmental pollution have mainly negative effects on TFEE; pure efficiency changes, scale efficiency changes, economic structure, opening up, and government finance have mainly positive effects on TFEE. Finally, precise policy implications are proposed.
اظهر المزيد [+] اقل [-]Estimation of methane and nitrous oxide emission from wetland rice paddies with reference to global warming potential النص الكامل
2019
Gorh, Dipti | Baruah, Kushal Kumar
Methane (CH₄) and nitrous oxide (N₂O) are two important greenhouse gases (GHG) and contribute largely to global warming and climate change. The impact of physiological characteristics of rice genotypes on global warming potential (GWP) and greenhouse gas intensity (GHGI) is not well documented. A 2-year field experiment was conducted with eight summer rice varieties: Dinanath, Joymoti, Kanaklata, Swarnabh, IR 64, Tapaswami (modern varieties), Number 9, and Jagilee Boro (indigenous varieties) for two successive seasons (December–June, 2015–2016 and December–June, 2016–2017) to estimate their GWP and GHGI. The GWP of the rice varieties ranged from 841.52 to 1288.67 kg CO₂-equiv. ha⁻¹ and GHGI from 0.184 to 0.854 kg CO₂-equiv. kg⁻¹ grain yield. Significant differences (p < 0.05) in seasonal GHG emission, GWP, GHGI, CEE (carbon equivalent emission), photosynthetic efficiency, stomatal conductance, transpiration rate, and grain productivity among the rice varieties were observed during the investigation. A good correlation of GWP (p < 0.01) was recorded with rate of stomatal conductance and transpiration rate of the varieties. The present study reveals a strong relationship between plant biomass (p < 0.01) with GWP and CEE of the rice varieties. The variety IR 64 and Number 9 are identified as the most suitable variety with lowest GWP (909.85 and 876.68 kg CO₂-equiv. ha⁻¹ respectively) and GHGI (0.192 and 0.227 kg CO₂-equiv. kg⁻¹ grain yield respectively) accompanied by higher grain productivity (4839 and 3867 kg ha⁻¹ respectively). Observations from the study suggest that agricultural productivity and GHG mitigation can be simultaneously achieved by proper selection of rice genotypes.
اظهر المزيد [+] اقل [-]Effect of acute ammonia exposure on the glutathione redox system in FFRC strain common carp (Cyprinus carpio L.) النص الكامل
2019
Li, Li-Hong | Qi, Hong-Xue
Ammonia is one of the most common aquatic pollutants. To analyze the effect of ammonia exposure on the glutathione redox system, we investigated the levels of hydrogen peroxide (H₂O₂) and glutathione, and transcription and activities of glutathione-related enzymes in liver and gills of FFRC strain common carp (Cyprinus carpio L.) exposed to 0, 10, 20, and 30 mg/L of ammonia. The results showed that H₂O₂ content reached a maximum level at 48 h of exposure in the liver of fish. In gills, H₂O₂ increased rapidly at 6 h and reached to maximum levels at 24 h of exposure, indicating that gills experienced oxidative stress earlier than the liver of fish exposed to ammonia. Reduced glutathione (GSH) content and reduced glutathione/oxidized glutathione (GSH/GSSG) ratio increased significantly within 24 h of exposure. Meanwhile, the transcription and activities of glutathione S-transferase (GST) and glutathione reductase (GR) increased significantly in the liver, and glutathione peroxidase (GSH-Px) and GST increased in the gills of fish exposed to ammonia. Malondialdehyde (MDA) content kept at a low level after exposure to low concentration of ammonia, but increased significantly after exposure to 30 mg/L ammonia for 48 h along with a decrease in GSH content and GSH/GSSG ratio. These data showed that the glutathione redox system played an important role in protection against ammonia-induced oxidative stress in the liver and gills of FFRC strain common carp, though the defense capacity was not able to completely prevent oxidative damage occurring after exposure to higher concentration of ammonia. This research systematically studied the response of the glutathione redox system to ammonia stress and would provide novel information for a better understanding of the adaptive mechanisms of fish to environmental stress.
اظهر المزيد [+] اقل [-]Hydrological tracers, the herbicide metazachlor and its transformation products in a retention pond during transient flow conditions النص الكامل
2019
Ulrich, Uta | Lange, Jens | Pfannerstill, Matthias | Loose, Lukas | Fohrer, Nicola
Since decades, surface water bodies have been exposed to pesticides from agriculture. In many places, retention systems are regarded as an important mitigation strategy to lower pesticide pollution. Hence, the processes governing the transport of pesticides in and through a retention system have to be understood to achieve sufficient pesticide attenuation. In this study, the temporal dynamics of metazachlor and its transformation products metazachlor-oxalic acid (OA) and –sulphonic acid (ESA) were observed in an agricultural retention pond and hydrologic tracers helped to understand system-inherent processes. Pesticide measurements were carried out for 80 days after their application during transient flow conditions. During a short-term (3 days) experiment, the tracers bromide, uranine and sulphorhodamine B were used to determine hydraulic conditions, residence times and sorption potential. A long-term experiment with sodium naphthionate (2 months) and isotopes (12 months) provided information about inputs via interflow and surface-groundwater interactions. During transient conditions, high concentration pulses of up to 35 μg L⁻¹ metazachlor, 14.7 μg L⁻¹ OA and 22.5 μg L⁻¹ ESA were quantified that enduringly raised solute concentrations in the pond. Mean residence time in the system accounted for approximately 4 h showing first tracer breakthrough after 5 min and last tracer concentrations 72 h after injection. While input via interflow was confirmed, no evidence for surface-groundwater interaction was found. Different tracers illustrated potentials for sorption and photolytic degradation inside the system. This study shows that high-resolution sampling is essential to obtain robust results about retention efficiency and that hydrological tracers may be used to determine the governing processes.
اظهر المزيد [+] اقل [-]Modeling CO2 emissions in an emerging market: empirical finding from ARDL-based bounds and wavelet coherence approaches النص الكامل
2019
Kalmaz, Demet Beton | Kirikkaleli, Dervis
This study aims to investigate the long-run and causal effects of energy consumption, economic growth, urbanization, and trade openness on CO₂ emissions in Turkey using newly developed econometric techniques. To our best knowledge, there has been no study examining the relationship between CO₂ emissions, energy consumption, trade openness, urbanization, and economic growth in Turkey. Therefore, this study proposes to fill this gap in the literature. In this study, we use time series data covering the years between 1960 and 2015. To capture long-run effects, we used ARDL, FMOLS, and DOLS estimators, while wavelet coherence technique is used to explore causal effects among the variables. Our results reveal that (i) there is a long-run equilibrium relationship between CO₂ emissions and energy consumption, economic growth, urbanization, and trade openness; (ii) in the long-run, CO₂ emission in Turkey is significantly triggered by energy consumption, economic growth, and urbanization; and (iii) the results of the wavelet coherence–based causality test provide supportive evidence to the long-run estimations of this study.
اظهر المزيد [+] اقل [-]Investigating the Effect of Medicago sativa L. and Trifolium pratense L. Root Exudates on PAHs Bioremediation in an Aged-Contaminated Soil النص الكامل
2019
Davin, Marie | Starren, Amandine | Marit, Emilie | Lefébure, Kévin | Fauconnier, Marie-Laure | Colinet, Gilles
Investigating the Effect of Medicago sativa L. and Trifolium pratense L. Root Exudates on PAHs Bioremediation in an Aged-Contaminated Soil النص الكامل
2019
Davin, Marie | Starren, Amandine | Marit, Emilie | Lefébure, Kévin | Fauconnier, Marie-Laure | Colinet, Gilles
Polycyclic aromatic hydrocarbons (PAH) are persistent organic compounds of major concern that accumulate in the environment, especially soils, and require remediation. Researches to develop bioremediation and phytoremediation (alternative eco-friendly technologies) are being conducted. First, a bioaccessibility measurement protocol was adapted to a brownfield soil using Tenax® beads in order to compare PAHs bioaccessibility in soil samples. PAHs desorption kinetics were established, described by a site distribution model, and a common extraction time was calculated (48 h). Second, the role of two Fabaceae (Medicago sativa L. or Trifolium pratense L.) root exudates in enhancing PAHs bioaccessibility and biodegradation in the studied soil was evaluated during microcosms experiments (28 °C). The CO₂ emissions were significantly higher in presence of T. pratense exudates; the dehydrogenase activities showed improvements of the soil microbial activity in presence of two types of root exudates compared to untreated soil samples; the PAHs residual contents decreased more in untreated samples than in the presence of T. pratense exudates; and M. sativa exudates lowered PAHs bioaccessibility but not residual contents.
اظهر المزيد [+] اقل [-]Investigating the Effect of Medicago sativa L. and Trifolium pratense L. Root Exudates on PAHs Bioremediation in an Aged-Contaminated Soil النص الكامل
2019
Davin, Marie | Starren, Amandine | Marit, Emilie | Lefébure, Kévin | Fauconnier, Marie-Laure | Colinet, Gilles
peer reviewed | Polycyclic aromatic hydrocarbons (PAH) are persistent organic compounds of major concern that accumulate in the environment, especially soils, and require remediation. Researches to develop bioremediation and phytoremediation (alternative eco-friendly technologies) are being conducted. First, a bioaccessibility measurement protocol was adapted to a brownfield soil using Tenax® beads in order to compare PAHs bioaccessibility in soil samples. PAHs desorption kinetics were established, described by a site distribution model, and a common extraction time was calculated (48 h). Second, the role of two Fabaceae (Medicago sativa L. or Trifolium pratense L.) root exudates in enhancing PAHs bioaccessibility and biodegradation in the studied soil was evaluated during microcosms experiments (28 °C). The CO2 emissions were significantly higher in presence of T. pratense exudates; the dehydrogenase activities showed improvements of the soil microbial activity in presence of two types of root exudates compared to untreated soil samples; the PAHs residual contents decreased more in untreated samples than in the presence of T. pratense exudates; and M. sativa exudates lowered PAHs bioaccessibility but not residual contents.
اظهر المزيد [+] اقل [-]The Possibilities of Using Broadleaf Cattail Seeds (Typha latifolia L.) as Super Absorbents for Removing Aromatic Hydrocarbons (BTEX) from an Aqueous Solution النص الكامل
2019
Ciesielczuk, Tomasz | Rosik-Dulewska, Czesława | Poluszyńska, Joanna
Sorption of oil-related products (including mainly the propellants) is the very basic process that counteracts spreading these types of pollution into environment. Plenty of synthetic substances (including the monoaromatic hydrocarbons) are both from the surface and underground waters. The aim of this study was to present the research’s results on the possibilities of using the broadleaf cattail (Typha latifolia L.) seeds as a sorbent of monoaromatic hydrocarbons from an aqueous solution. In order to increase sorptive capacity, the seeds biomass was submitted for the process of mercerizing in diversified time and temperature in water and the NaOH solution. The removal of benzene, toluene, ethylbenzene, o-xylene, m-xylene and cumene was carried out by means of the “batch method”. All the conducted experiments have shown a high sorption level of the analysed pollutions from an aqueous solution. The best sorptive qualities appeared in the seeds drenched in 80 °C water for 4 h (W) 97 g/kg, what was 9.06% more absorbed hydrocarbons in comparison to the control sample (C) and 26.8% more than the smallest seeds drenched in NaOH for 240 min. in the temperature of 80 °C (N). The process of the seeds mercerizing that was conducted with the use of hot water appeared to be most effective, but seeds without mercerisation (C) is actually the material which absorbs the least amounts of energy for preparation and had quite good sorption capacity too.
اظهر المزيد [+] اقل [-]Radionuclide Immobilization by Sorption onto Waste Concrete and Bricks—Experimental Design Methodology النص الكامل
2019
Jelić, Ivana | Šljivić-Ivanović, Marija | Dimović, Slavko | Antonijević, Dragi | Jović, Mihajlo | Vujović, Zoran | Smičiklas, Ivana
The utilization of construction and demolition waste materials for the radionuclide immobilization by sorption processes was investigated. Given that the liquid radioactive waste usually has a complex composition and that effects of competition may significantly influence the efficiency of the treatment, the Simplex Centroid experimental design was used to explore ions sorption from multi-component solutions. For the purpose of this study, the common components of construction and demolition waste, such as pathway concrete and different bricks samples, were used along with the multi-component Sr²⁺, Co²⁺, and Ni²⁺ ions solutions. The equations for the prediction of metal ions sorption capacities were derived. The coefficients that correspond to the linear and interaction terms were obtained using a special cubic model. Likewise, by analysis of variance, statistically significant terms of the obtained polynomial were defined. The investigation has shown that the most effective sorption was onto the pathway concrete for all three cations, while the highest sorption capacity was found for Co²⁺ ions. Also, it has been determined that concerning Sr²⁺ ion removal there was a competition with coexisting Co²⁺ and Ni²⁺ ions, reducing its sorption capacity, while sorption of Co²⁺ and Ni²⁺ occurred more independently on other cations in multi-component solutions. Based on the obtained results, the applied experimental design can be efficiently used for the description of competitive sorption process and could be a powerful tool for the prediction of cation immobilization in liquid radioactive waste treatment.
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