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Результаты 5551-5560 из 6,560
Biodegradation of microcystin-RR and nutrient pollutants using Sphingopyxis sp. YF1 immobilized activated carbon fibers-sodium alginate Полный текст
2020
Ren, Guofeng | He, Xinghou | Wu, Pian | He, Yayuan | Zhang, Yong | Tang, Shibiao | Song, Xinli | He, Yafei | Wei, Yuandan | Ding, Ping | Yang, Fei
A novel biological material named activated carbon fibers-sodium alginate@Sphingopyxis sp. YF1 (ACF-SA@YF1) was synthesized for microcystin-RR (MC-RR) and nutrient pollutant degradation in eutrophic water. The synthesized biomaterial was characterized by scanning electron microscopy (SEM). Box-Behnken design and response surface methodology (RSM) were utilized for the optimization of conditions during the MC-RR degradation. The degradation of MC-RR and nutrient pollutants was dynamically detected. The results revealed that the optimal conditions were temperature 32.51 °C, pH 6.860, and inoculum 14.97%. The removal efficiency of MC-RR, nitrogen, phosphorus, and chemical oxygen demand were 0.76 μg/mL/h, 32.45%, 94.57%, and 64.07%, respectively. In addition, ACF-SA@YF1 also performed satisfactory cyclic stability, while the MC-RR removal efficiency was 70.38% after seven cycles and 78.54% of initial activity after 20 days of storage. Therefore, it is reasonable to believe that ACF-SA@YF1 is an effective material which has a great prospect in removing MC-RR and nutrients from freshwater ecosystems.
Показать больше [+] Меньше [-]Oxidative stress risk assessment through heavy metal and arsenic exposure in terrestrial and aquatic bird species of Pakistan Полный текст
2020
Kanwal, Shamsa | Abbasi, Naeem Akhtar | Chaudhry, Muhammad Jamshed Iqbal | Ahmad, Sajid Rashid | Malik, Riffat Naseem
In this study, we investigated metal- and metalloid-induced oxidative stress response in two aquatic (cattle egret (Bubulcus ibis) (n = 10), pond heron (Ardeola grayii) (n = 10)), as well as two terrestrial (spotted owlet (Athene brama) (n = 6) and bank myna (Acridotheres ginginianus) (n = 16)) bird species collected from the outskirts of Lahore city, Pakistan. For this purpose, glutathione (tGSH) and lipid peroxidation (thiobarbituric acid-reactive substances (TBARS)) levels and activities of antioxidant enzymes (superoxide dismutase (SOD); catalase (CAT)) were analyzed as biomarkers of oxidative stress against metal (Pb, Cd, Cu, Zn) and metalloid (As) concentrations in kidney liver and blood of birds. Our results depicted significant correlation for Pb, Cd, and As with oxidative stress biomarkers in birds. The levels of heavy metals and As and their corresponding effects on oxidative stress biomarkers were comparably higher in aquatic species (p ≤ 0.01) except for Pb and Zn. In comparison of species, SOD and tGSH activities were higher in bank myna and cattle egret, while CAT activity and TBARS concentrations were higher in pond heron and cattle egret, respectively. We deduced that tissues with higher accumulation of metal(loid)s such as liver and kidney were under a great risk to oxidative damage. The overall order of metal accumulation and subsequent oxidative damage among families followed the pattern as Strigidae ≥Ardieda ≥ Sturnidae with their respective trophic levels. Globally, metal- and As-induced oxidative stress is least emphasized in multiple tissues of birds that is needed to be addressed with focus on case-control studies using dose-response approach. Graphical abstract .
Показать больше [+] Меньше [-]Modeling the nexus between coal consumption, FDI inflow and economic expansion: does industrialization matter in South Africa? Полный текст
2020
Udi, Joshua | Bekun, Festus Victor | Adedoyin, Festus Fatai
This study examines the role of industrialization in the energy-growth-FDI nexus for the case of South Africa using data over the period 1970 to 2018. The empirical exercise was conducted using Pesaran Autoregressive Distributed Lag (ARDL) bounds testing approach. To accomplish our study objective, we analyze stationarity properties of the series using the unit root test after which we applied Bayer-Hanck (B-H) combined technique to cointegration to assess whether a long-run relationship exists among the series. Empirical results show that a 1% change in FDI account for 0.002% and 0.013% increase in economic expansion in the short- and long- run respectively. Also, a 1% increase in coal consumption influence GDP negatively by 0.083% and 0.207% in the short and long run respectively. Furthermore, a 1% increase in total natural resource rent positively affects GDP by 0.02% and 0.05% respectively in the short and long run. Industrialization, on the other hand, demonstrates a positive and significant impact on the economic growth process both in the short and long run. Industrialization contributes 0.506% and 1.274% to economic expansion both in the short and long run respectively. The causality tests suggest that a one-way causal link running from FDI to industrialization and from industrialization to coal consumption exists. Finally, FDI inflow drives total natural resource rents in South Africa. This study also gives reliable growth and energy policy proposals to policymakers applicable to countries around the globe.
Показать больше [+] Меньше [-]Solid wastes from the enzyme production as a potential biosorbent to treat colored effluents containing crystal violet dye Полный текст
2020
Grassi, Patrícia | Drumm, Fernanda C. | Spannemberg, Stéfani S. | Georgin, Jordana | Tonato, Denise | Mazutti, Marcio A. | Gonçalves, Janaína O. | Oliveira, Marcos L. S. | Dotto, Guilherme L. | Jahn, Sérgio L.
Sugarcane bagasse, a largely available waste worldwide, was submitted to solid-state fermentation (SSF) using the fungus Metarhizium anisopliae, aiming to produce enzymes. The solid waste generated from SSF was tested as an alternative biosorbent to treat colored effluents containing crystal violet (CV) dye. The biosorbent, here named BW (bagasse waste), was characterized, and experimental tests were performed to verify the influence of pH and dosage on the CV biosorption. Isotherms and biosorption kinetics were performed, and the biosorption thermodynamic parameters were determined. The potential of BW was also evaluated for the treatment of a simulated textile effluent. The maximum biosorption capacity was 131.2 mg g⁻¹ at 328 K, and the Liu was the most appropriate model to represent equilibrium data. The biosorption was spontaneous and endothermic. The use of BW in the simulated effluent showed that it is an efficient material, reaching color removal values of 85%. Therefore, the sugarcane bagasse generated from SSF can be considered a potential biosorbent to remove CV from textile effluents. This finding is relevant from the total environment viewpoint, since, at the same time, SSF generates enzymes and a solid waste, which in turn can be used as biosorbent to treat colored effluents.
Показать больше [+] Меньше [-]Environmentally relevant exposures of male mice to carbendazim and thiram cause persistent genotoxicity in male mice Полный текст
2020
Rai, Bina | Mercurio, Steven Don
Carbendazim and thiram are fungicides used in combination to prevent mold destruction of crops. Studies have demonstrated genotoxicity by these agents, but have not used concentrations below their water solubility limits in drinking water to test for persistence of genotoxicity due to chronic exposure. Ten 8-week old male Swiss-Webster mice were exposed to tap water, or nominal concentrations of 20 μM carbendazim, 20 μM thiram or 20 μM of both fungicides for 90 days (total of 40 mice). Five mice from tap water controls, carbendazim, thiram and combination-treated groups (20 mice total) had genotoxicity detected by comet assay of lymphocytes at the termination of the exposure period. The other 20 mice (4 treatment groups) were all switched to tap water and allowed a 45-day recovery period to check for persistence of DNA damage. The damage was compared with commercial control cells exposed to increasingly harsh treatment by etopside. Comet assay (mean % tail DNA + SE) of control mice (9.8 + 0.9) was similar to commercial control (CC0) cells (8.5 + 0.9). Carbendazim, thiram or the combination treatment caused similar mean % tail DNA with 33.0 + 2.9, 30.1 + 3.3 and 29.1 + 1.8, respectively, comparable with commercial cells slightly damaged by etopside (CC1 with 31.4 + 2.9) with no statistical change in water or food intake, body weight or liver or kidney weights. The key result was that a 45-day recovery period had no observable difference in the DNA damage as assessed by DNA % in comet tail with tap water controls and CCO control cells at 7.0 + 0.7 and 9.7 + 1.2 versus 27.5 + 1.9, 29.3 + 2.2 and 32.0 + 1.8, respectively, for carbendazim, thiram and combination treatments. It is of concern that the use of these agents in developing countries with little training or regulation results in water pollution that may cause significant persistent DNA damage in animal or human populations that may not be subject to repair.
Показать больше [+] Меньше [-]The risk of cross-border pollution and the influence of regional climate on the rainwater chemistry in the Southern Carpathians, Romania Полный текст
2020
Keresztesi, Ágnes | Nita, Ion-Andrei | Birsan, Marius-Victor | Bodor, Zsolt | Szép, Róbert
The aim of this study is the assessment of rainwater composition, regarding the various sources of major ions and heavy metals, taking into account the characteristic atmospheric circulations and the main air mass transport routes. Rainwater samples were analyzed for pH, electrical conductivity, major ions, and heavy metals. At all sampling sites, the most abundant anions were SO₄²ˉ and Clˉ, while the dominant cations were Ca²⁺ and Mg²⁺. Regarding heavy metals, the dominance of Pb and Cd was found. The contribution of soil dust from the mining activities and the dissolution of CaCO₃, MgCO₃, and CaSO₄·2H₂O in the rainwater explains the high concentrations of Ca²⁺, Mg²⁺, and SO₄²⁻. The overall precipitation contamination with heavy metals at the three sampling sites was assessed by the degree of contamination, showing that Pb and Cd presents the highest risks of all heavy metals. The values of toxicity potential suggested an elevated risk for human health in case of rainwater ingestion, especially in rural areas. Spearman correlation and PCA indicated that the chemical characteristic of the rainwater is primarily controlled by sources such as agricultural activities, mixed and crustal sources, traffic, and other anthropogenic, industrial influences, mining activities, smelting operations, coal combustion, and metal production.
Показать больше [+] Меньше [-]Environmental quality assessment of the fish farms’ impact in the Monastir Bay (eastern of Tunisia, Central Mediterranean): a benthic foraminiferal perspective Полный текст
2020
Damak, Mohamed | Fourati, Rania | Elleuch, Boubaker | Kallel, Monem
Offshore fish farms have been active inside the Monastir Bay, Hammemet Gulf for over 10 years, but their environmental impact is still unknown. This study focuses on the evaluation of the fish farming activity impact in the Monastir Bay as revealed by geochemical and benthic foraminiferal data. Samples were collected around three fish cages at different water depths. Total organic carbon (TOC) and total phosphate (TP) in the sediment show higher values beneath the fish cages and decrease proportionally with distance from the cages. Living foraminiferal assemblages around fish farms are dominated by stress-tolerant species with higher abundances of Ammonia tepida, Rosalina bradyi, Elphidium crispum, and Peneroplis planatus. On the basis of our results, A. tepida and Quinqueloculina seminula are confirmed to be tolerant to elevated nutriment content, while Ammonia parkinsoniana seems to be more sensitive to organic enrichment. We also test the Foram-AMBI that is revealed to be a very promising tool by which evaluating the ecological quality status of marine sediment. The results of the present study confirm the suitability of living benthic foraminifera as bioindicators of organic enrichment induced by aquaculture activities.
Показать больше [+] Меньше [-]Trace metal trophic transference and biomagnification in a semiarid coastal lagoon impacted by agriculture and shrimp aquaculture Полный текст
2020
Jara-Marini, Martín Enrique | Molina-García, Araceli | Martínez-Durazo, Ángel | Páez Osuna, Federico
We studied the biomagnification of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) with carbon (C) and nitrogen (N) stable isotope analyses during four seasons, in the food web of a semiarid coastal lagoon in the central-eastern Gulf of California (GC). The concentrations of the four metals increased among functional organism groups, from the food web base to the highest trophic levels. In general, the distribution of the elements for the four sampled seasons was Zn > Cu > Pb > Cd. The correlations between trophic level values and log-transformed metal concentrations were significantly (p < 0.05) positive for Cd (r = 0.61–0.91), Cu (r = 0.63–0.70), and Zn (r = 0.50–0.73), while Pb showed only one positive correlation (r = 0.38). The biomagnification factors (from specific predator-prey scenarios) ranged from 0.32 to 3.88 for Cd, 0.05 to 37.1 for Cu, 0.50 to 3.57 for Pb, and 0.70 to 22.2 for Zn. The trophic biomagnification factors (considering the entire food web) varied from 1.26 to 1.41 for Cd, 1.95 to 2.24 for Cu, 1.02 to 1.15 for Pb, and 1.45 to 1.78 for Zn. Our results show evidence for the biomagnification of Cd, Cu, and Zn in the studied food web, while data on Pb transference are not conclusive.
Показать больше [+] Меньше [-]The role of financial development, energy demand, and technological change in environmental sustainability agenda: evidence from selected Asian countries Полный текст
2020
Saleem, Hummera | Khan, Muhammad Bilal | Shabbir, Malik Shahzad
The study seeks to examine the policy scheme of Asian countries and their efforts to achieve sustainable environmental practices in terms of green growth, green financing, and CO2emission reduction programs. This study investigates the role of GDP growth, sources of energy consumption, and other plausible hypothetical factors in CO₂ emissions using evidence from selected Asian countries over the period of 1980–2015. The contribution of this research is unique, with the use of these plausible variables under the framework of EKC, which makes this study different from other studies and helps fill a gap in the literature. This study has used panel Fully Modified OLS (FMOLS) test, the panel Granger causality test namely the Dumitrescu-Hurlin test (2012) and the Innovative Accounting Approach. The results of FMOLS for the full panel set indicates the presence of an EKC hypothesis, where the impact of GDP growth and the square of GDP growth on CO2 emissions are positive and negative, respectively, in the context of 10 Asian economies. The findings of FMOLS for lower income economies do not support the EKC hypothesis; however, the results exhibit that high and upper middle income economies maintain the EKC hypothesis. The results of high income and upper middle income economies confirm the existence of the environment Kuznets curve, and the results of GDPᵢₜ show that both significantly positively impact logGDPᵢₜon CO2 emission.
Показать больше [+] Меньше [-]Farnesoid X receptor mediates hepatic steatosis induced by PM2.5 Полный текст
2020
Wang, Mengyao | Tan, Jieqiong | Zhou, Ji | Yi, Bin | Huang, Zhijun
Ambient particulate matter (PM) newly has been regarded as a conceivable hazard for public health. A large number of studies have described that PM, exceptionally PM₂.₅, is correlated with respiratory, cardiovascular, and metabolic diseases, etc. PM₂.₅-induced hepatocyte steatosis previously has been uncovered both in cellular and murine models. Nevertheless, less is known about the underlying mechanism. Here, we found that PM₂.₅ could cause the downregulation of farnesoid X receptor (FXR), a key transcription factor for lipid metabolism. FXR could regulate the accumulation of lipid droplets induced by PM₂.₅ in vitro. Moreover, FXR⁻/⁻ mice were exposed to PM₂.₅ for 2 months to investigate the role of FXR in pathogenesis of PM₂.₅-induced hepatic steatosis in vivo. The results showed that exposure of wild-type (WT) mice to PM₂.₅ caused mild liver steatosis compared with the mice exposure to filtered air (FA). Furthermore, the content of triglyceride (TG) and total cholesterol (TC) was elevated in WT mice liver triggered by the inhalation of PM₂.₅. However, there was no statistical difference in TG and TC content between FXR⁻/⁻ mice with and without PM₂.₅ exposure. Overall, our finding suggested FXR mediated PM₂.₅-induced hepatic steatosis.
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