خيارات البحث
النتائج 3771 - 3780 من 6,535
Exploring of toxic Pb(II) removal by low-cost bio-adsorbent of camphor leaf forestry waste after camphor oil extraction
2020
Xu, Sheng | Xiao, Huiru | Jiang, Xinde | Liu, Lingli | Cao, Meng | Wang, Zhenxi
Camphor leaf (CL) was widely used to extract camphor oil and thus led to abundant forestry waste. In order to reduce pollution, the waste CL was used to prepare bio-adsorbent for Pb(II) removal after alkali treatment and functional modification. The effects of solution pH, initial Pb(II) concentration, contact time and solution temperature were investigated on adsorption process to evaluate the potential application in heavy metal ions’ removal. It was found that the massive hydroxyl groups released and plenty of micro-pores formed after the alkali treatment of CL bio-adsorbent, which obviously increased the Pb(II) adsorption. And the adsorption performance promoted continually after further functional modification by ionized 1,2,3,4-butanetetracarboxylic acid (BTCA). The increase of pH was favourable for the adsorption even though the precipitation effect was deducted. Linear fitting method was more suitable to describe the adsorption process than nonlinear fitting method, including adsorption isotherms and adsorption kinetics research. The adsorption thermodynamics was better to be described by nonlinear fitting method due to its lower root mean square error (RMSE) value and higher R² value. Among which, the adsorption isotherm and adsorption kinetics were fitted well to Langmuir model and pseudo-second-order model, respectively. The adsorption thermodynamics was exothermic in nature and the process was spontaneous at low solution temperature. The adsorption mechanism was revealed as the combination of dominant chemical adsorption and assistant physical adsorption.
اظهر المزيد [+] اقل [-]Does globalization in Turkey induce increased energy consumption: insights into its environmental pros and cons
2020
Etokakpan, Mfonobong Udom | Adedoyin, Festus Fatai | Vedat, Yorucu | Bekun, Festus Victor
Globalization is the paradigm shift to a more integrated world economy broadly shaping economies and societies around the globe. The wave of globalization is much more eminent on its impact on increased energy demand, knowledge and technology transfer, trade, and financial capital flows. The present study focuses on Turkey, a fast-emerging economy that is no exception to the wave of globalization. This current study explores the dynamics between ecological footprints, energy consumption, and real income level for the case of Turkey in a carbon-income function while accounting for other covariate like globalization to avoid omitted variable bias. The study data spans from 1970 to 2017 on an annual frequency basis. The stationarity properties of the outlined variables were investigated. Subsequently, the equilibrium relationship between the variables is confirmed by the battery of recent robust estimation techniques. While to detect the causality of direction among the variables, the Modified Wald test causality test is utilized. This study reveals that an increase in energy consumption in Turkey reduces environmental pollution by a magnitude of 0.37% in the short run and 0.43% long run, while an increase in economic expansion dampens the quality of the environment 0.42% and 0.72% on both short and long-run basis. This is indicative given that Turkey is more energy conscious and energy efficient, while a positive statistically significant relationship is observed between real income level and ecological footprint and globalization index. The causality analysis also supports the growth-induced energy consumption hypothesis. The study further offers policy direction for the energy sector in Turkey in the face of global interconnectedness.
اظهر المزيد [+] اقل [-]Air pollution inhalation during acute exercise is dependent of the body mass index and ventilation of young men
2020
Marmett, Bruna | Carvalho, Roseana Böek | Dorneles, Gilson Pires | da Silva, Igor Martins | Romão, Pedro Roosevelt Torres | Nunes, Ramiro Barcos | Rhoden, Cláudia Ramos
Obesity and physical inactivity threaten human health, and both could be solved with exercise. However, a higher amount of pollutants is inhaled during exercise. Exposure to air pollution increases the incidence and progression of diseases. Therefore, the aim of the study was to investigate the rate of pollution inhalation of lean, overweight, and obese individuals in a low and high-intensity hypothetical exercise session. Healthy sedentary men (n = 135) classified as lean, overweight, or obese were enrolled in our study. All participants performed a cardiopulmonary exercise testing (CPX) to collect ventilation rate (VE) data, which was used to predict total ventilation and pollutant inhalation of a 5-km running session. Air pollutant concentration of São Paulo City, Brazil was evaluated and the toxicological risk was estimated based on the potential intake dose. The concentrations of PM₂.₅ were 29.57 μg/m³ and 51.71 μg/m³, PM₁₀ were 45.85 μg/m³ and 74 μg/m³, NO₂ were 63.71 μg/m³ and 66.65 μg/m³, and O₃ were 69 μg/m³ and 37 μg/m³, respectively in the summer and winter. In the hypothetical exercise session, total VE and time in both the first and second threshold were increased in the obese group (p < 0.001) (p < 0.001). The inhalation of PM₂.₅, PM₁₀, NO₂, and O₃, during the hypothetical session, was increased in obese individuals (p < 0.001). Obese individuals should be considered a susceptible population, once they are more exposed to air pollution during exercise.
اظهر المزيد [+] اقل [-]Towards sustainable management of tomato pomace through the recovery of valuable compounds and sequential production of low-cost biosorbent
2020
Azabou, Samia | Louati, Ibtihel | Ben Taheur, Fadia | Nasri, Moncef | Mechichi, Tahar
The present study focused on the full valorization of the tomato by-product, also known as tomato pomace consisting mainly of tomato peels and tomato seeds, by recovering natural antioxidants and edible oil, and subsequently reutilizing the leftover solid residues for the production of low-cost biosorbent. The tomato peel extract recovered using ethanol as food-grade solvent contained high phenol and flavonoid contents (199.35 ± 0.35-mg gallic acid equivalents (GAE)/g and 102.10 ± 0.03-mg quercetin equivalent (QE)/g, respectively). Even its lower content of lycopene (3.67 ± 0.04 mg/100 g), tomato peel extract showed potent antioxidant activity and can be therefore used as natural antioxidants either for food or cosmetic applications. High nutritional quality edible oil (17.15%) was extracted from tomato seeds and showed richness in unsaturated fatty acids (74.62%), with linoleic acid being the most abundant polyunsaturated fatty acid (49.70%). After recovery of these valuable compounds, the extraction solid leftovers were used to produce low-cost biosorbent tested for dye removal. Results showed that the highest biosorption yields were increasingly attributed to the acidic, direct, anthraquinone, then reactive dyes. Overall, the obtained results strongly support the complete utilization of tomato pomace for the recovery of valuable compounds and the sequential production of low-cost biosorbent.
اظهر المزيد [+] اقل [-]Investigation on key contributors of energy consumption in dynamic heterogeneous panel data (DHPD) model for African countries: fresh evidence from dynamic common correlated effect (DCCE) approach
2020
Adjei-Mensah, I. K. | Sun, Mei | Gao, Cuixia | Omari-Sasu, Akoto Yaw | Sun, Huaping | Ampimah, Benjamin Chris | Quarcoo, Alfred
The main aim of this current study is to empirically scrutinize the determinants of energy consumption for 24 African countries sub-grouped into three panels based on income levels: low-, lower-middle-, and upper-middle-income countries, from 1990 to 2015. Due to the presence of heterogeneity and cross-sectional reliance among country groups, recently developed econometric approaches, which include cross-sectional Im, Pesaran, and Shin together with cross-sectional Augmented Dickey-Fuller stationarity tests, Pedroni and Westerlund–Edgerton cointegration assessment, dynamic common correlated effect estimation approach and Dumitrescu–Hurlin Granger causality test are employed. Empirically, our findings depict analyzed variables are stationary and characterized by long-term stability affiliations for all panels. Economic growth, urbanization, population growth, and oil price with labor and capital stock as intermittent variables had palpable significant positive sway on energy consumption for all panels though their respective weight of contribution differed from one country group to another. The granger test of causation unveiled that (i) among all panels, urbanization and energy consumption are connected bidirectionally, whereas population growth causes energy consumption; (ii) a one-way causal link from economic growth to energy use is evidenced in low-income African countries, whereas a two-sided connection is confirmed in both lower-middle- and upper-middle-income economies; (iii) a bilateral causal association in low-income African nations is observed amid oil price and energy use, while a uni-lateral relationship extends from oil price to energy consumption in both lower-middle- and upper-middle-income nations in Africa. Such new methodologies and findings reveal that the long-term estimated effects as well as causal affiliations amid variables are skewed by different income levels of African countries in an attempt to conserve energy. Policy recommendations are further propose.
اظهر المزيد [+] اقل [-]Polymer types ingested by northern fulmars (Fulmarus glacialis) and southern hemisphere relatives
2020
Kühn, Susanne | Oyen, van, Albert | Bravo Rebolledo, Elisa L. | Ask, Amalie V. | Franeker, van, Jan Andries
Although ingestion of plastic by tubenosed seabirds has been documented regularly, identification of the polymer composition of these plastics has rarely been described. Polymer assessment may assist in identifying sources and may indicate risks from additives occurring in specific types of polymers. Using known test materials, two identification methods Fourier transform infrared spectroscopy and near infrared spectroscopy (FTIR and NIR) were compared. Although both methods were found to be similarly suitable for identification of plastic polymers, a significant difference was observed in identification of natural materials. FTIR frequently misclassified natural materials as being a synthetic polymer. Within our results, an 80% match score threshold functioned best to distinguish between natural items and synthetics. Using NIR, the historical variability of plastics ingested by northern fulmars (Fulmarus glacialis) from the Dutch sector of the North Sea was analysed for three time periods since the 1980s. For the more recent decade, variability between fulmars from different regions in the northeast Atlantic was investigated. Regional variation was further explored by analysing plastics obtained from the stomachs of southern hemisphere relatives of the fulmar (southern fulmar, cape petrel, snow petrel) and Wilson’s storm petrel. Results show that proportional abundance of polymer types in these seabirds is closely related to the plastic categories that they ingest (e.g. pellets, foam, fragments). The uptake of different plastic categories and related polymer types most likely reflects spatial and temporal variations in availability rather than ingestion preferences of the birds.
اظهر المزيد [+] اقل [-]Effect of Activated Sludge on the Degradation of 2-Ethylhexyl 4-Methoxycinnamate and 2-Ethylhexyl 4-(Dimethylamino)Benzoate in Wastewater
2020
Gackowska, Alicja | Studziński, Waldemar
Incomplete removal of organic pollutants during wastewater treatment is one of the main routes to introduce micro-pollutants into the environment. This group of pollutants includes, among others, UV filters. Commonly used UV filters are 2-ethylhexyl 4-methoxycinnamate (EHMC) and 2-ethylhexyl 4-(dimethylamino)benzoate (ODPABA). Due to the lipophilic character, these compounds can accumulate in sludge. The effects of activated sludge on the removal of EHMC and ODPABA from wastewater have been investigated in this study. It was shown that both UV filters tend to accumulate in the sludge. The concentration of UV filters in sludge increased with the increase of activated sludge dose and time of process. It was checked whether EHMC and ODPABA were transformed in activated sludge. A gas chromatograph coupled with a mass spectrometry detector (GC-MS) was used to identify products. In the case of EHMC, ethylhexyl alcohol (EHA) and the Z-EHMC isomer were identified. Methyl-4-aminobenzoic acid (MPABA) was identified as ODPABA degradation product. Elimination of EHMC and ODPABA from wastewater mainly proceeds by adsorption of these pollutants in the sludge. Filters present in wastewater and sludge undergo transformations.
اظهر المزيد [+] اقل [-]Agronomic and environmental benefits of nutrient expert on maize and rice in Northeast China
2020
Wang, Yin | Li, Chunlin | Li, Yuxi | Zhu, Lin | Liu, Shuoran | Yan, Li | Feng, Guozhong | Gao, Qiang
Agricultural production in China is facing great challenges to ensure food security and cleaner environment; further improvements are therefore required in crop nutrient management to increase grain yield and nutrient use efficiency while synchronously reducing environmental pollution. In this study, a total of 87 site-years of on-farm experiments were conducted from 2013 to 2018 in the main agro-ecological areas in Northeast China, to evaluate the agronomic and environmental benefits of nutrient expert (NE) system in maize and rice production. Results showed that NE had general and significant advantages in agronomic and environmental benefits relative to FP, by dramatically reducing N and P fertilizer inputs and optimizing nutrient management. As compared to FP, on average, NE increased grain yield by 8.4% and 6.6% significantly higher grain yield and N uptake for maize, respectively, while it obtained equal yield performance and 3.0% higher N uptake for rice, and consequently resulted in significantly higher N use efficiency. Environmental effects assessment showed that NE reduced substantially reactive N losses and greenhouse gas emissions by 46.9% and 37.2% for maize, respectively, and 10.1% and 6.6% for rice, respectively. Regression analysis indicated that NE effectively improved N use efficiency and mitigated environmental pollution was mainly associated with increasing plant N uptake and reduced N surplus. As compared to fertilization recommendation based on soil testing, NE system showed higher N use efficiency and better environmental benefits for both maize and rice. In conclusion, our results demonstrated that NE system is a feasible and promising approach to optimize crop nutrient management and promote cleaner agricultural production in Northeast China.
اظهر المزيد [+] اقل [-]Characterization and Partitioning Behavior of Creosote in Different Matrices: Soil, Water, and Air
2020
Macêdo Aranha, Rayanne | A. Magalhães, Vivian M. | P. Mendes, Gabriela | R. Soares, Lélia C. | Muselli Barbosa, Alexandre | A. O. Nascimento, Claudio | M. G. R. Vianna, Marilda | Chiavone-Filho, Osvaldo
Creosote is a multicomponent oil classified as a dense non-aqueous phase liquid (DNAPL) produced from coal tar distillation. The concept of phase distribution is critical in decision-making to remediate contaminated sites. The creosote mass transfer between sorbed, aqueous, vapor, and DNAPL phases is controlled by physicochemical characteristics, geology of the site, and environment conditions. This study evaluated phase distribution of the main polycyclic aromatic hydrocarbons (PAHs) of creosote in a sandy soil with low organic matter content. The creosote was collected from a contaminated site in São Paulo, Brazil, and was characterized by gas chromatography–mass spectrometry (GC-MS). Clean soil was collected upgradient from the same area. Initially, the soil was artificially contaminated with creosote. After, the contaminated soil was put in contact with clean water in sealed vials for 72 h. Samples of the soil, vapor, and liquid phases were collected and analyzed by GC-MS. In total, 50 compounds were identified in the creosote, and 9 PAHs were selected to be studied, which represented around 30% of total creosote mass. The major contaminant concentration was detected in the sorbed phase. For instance, naphthalene mass was distributed in sorbed (33.0%), DNAPL (1.5%), aqueous (3.4%), and vapor (0.2%) phases. The results provided an understanding of the contaminant species partitioning that occurs in a real contaminated site.
اظهر المزيد [+] اقل [-]Effects of ethylene biosynthesis and signaling on oxidative stress and antioxidant defense system in Nelumbo nucifera G. under cadmium exposure
2020
Wang, Yanjie | Yuan, Man | Li, Zexin | Niu, Yeqing | Jin, Qijiang | Zhu, Bin | Xu, Yingchun
Water contamination with cadmium (Cd) is a global environmental problem and its remediation becomes urgent. Phytoremediation using ornamental plants has attracted much attention for its advantages of cost-effectiveness and beautification of the environment. Nelumbo nucifera G. is a popular ornamental aquatic macrophyte with fast growth, large biomass, and high capacities for Cd accumulation and removal. However, information about Cd resistance and defense responses in N. nucifera is rather scarce, which restricts its large-scale utilization for phytoremediation. The phytohormone ethylene plays an important role in plant resistance to Cd stress, but the underlying mechanism remains unclear. In this study, we investigated morphophysiological responses of N. nucifera seedlings to Cd stress, and focused on the effects of ethylene on oxidative damage, Cd accumulation, and antioxidant defense system at the metabolic and transcript levels in leaves under Cd stress. Our results showed that Cd exposure led to leaf chlorosis and necrosis, coupled with an increase in contents of hydrogen peroxide, electrolyte leakage, and malondialdehyde, and decrease in chlorophyll content. Exogenous ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) application intensified Cd-induced stress responses and Cd accumulation, and increased ethylene production by inducing ACC synthase (ACS) gene NnACS. Such enhanced ethylene emission inhibited catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) activities, and modulated ascorbate (AsA) and glutathione (GSH) accumulation through transcriptional regulation of their respective metabolic genes. After ethylene action inhibitor silver thiosulfate (STS) supplementation, Cd-induced oxidative damage was abolished, and Cd content declined but still at a relatively high level. Blocking of ethylene perception by STS inhibited ethylene biosynthesis; enhanced CAT, APX, and GR activities and their transcript levels; increased AsA accumulation via inducing its biosynthetic genes; but reduced GSH content and NnGSH2 expression level. These results suggest that ethylene biosynthesis and signaling play an important role in N. nucifera response to Cd stress, and maintaining appropriate ethylene level and low ethylene sensitivity could improve its Cd tolerance via efficient antioxidant defenses.
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