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Результаты 5221-5230 из 6,560
Histopathologic, apoptotic and autophagic, effects of prenatal bisphenol A and/or di(2-ethylhexyl) phthalate exposure on prepubertal rat testis Полный текст
2020
Balci, Aylin | Ozkemahli, Gizem | Erkekoglu, Pınar | Zeybek, Naciye Dilara | Yersal, Nilgun | Kocer-Gumusel, Belma
Bisphenol A (BPA) and di(2-ethylhexyl) phthalate (DEHP) are endocrine-disrupting chemicals (EDCs) used in a wide variety of industrial products as plasticizers. Exposure to EDCs, particularly in mixtures, in prenatal and early postnatal periods may lead to unwanted effects and can cause both developmental and reproductive problems. In this study, we aimed to determine the individual and combined effects of prenatal and lactational exposure to BPA and/or DEHP on testicular histology, apoptosis, and autophagic proteins. Pregnant Sprague-Dawley rats (n = 3) were divided into four groups (control, BPA (50 mg/kg/day), DEHP (30 mg/kg/day), and BPA (50 mg/kg/day) + DEHP (30 mg/kg/day)) and dosed by oral gavage during pregnancy and lactation. The male offspring (n = 6) from each group were chosen randomly, and their testicular examinations were performed on the twelfth week. The results showed that fetal and neonatal exposure to BPA and DEHP could lead to significant testicular histopathological alterations and cause increases in apoptosis markers (as evidenced by increases in caspase 3 and caspase 8 levels; increased TUNEL-positive spermatogonia and TUNEL-positive testicular apoptotic cells) and autophagic proteins (as evidenced by increased LC3 and Beclin levels and decreased p62 levels) in testicular tissue. We can suggest that EDCs cause more dramatic changes in both testicular structure and cell death when there is combined exposure.
Показать больше [+] Меньше [-]A toxicity-based analysis of Canada’s National Pollutant Release Inventory (NPRI): a case study in Nova Scotia Полный текст
2020
Taylor, Stephanie | Edwards, Stuart Johnston | Walker, Tony R.
After the success of the Toxics Release Inventory (TRI) in the United States (US), Canada created the National Pollutant Release Inventory (NPRI). Both NPRI and TRI focus on public opinion to coerce facilities to reduce quantities of emissions, through market pressure, although early reductions in Canada may be attributed to traditional command-and-control mechanisms. NPRI uses a quantity-based approach to report atmospheric and effluent releases of pollutants to air and water, but does not account for relative toxicity of releases, which could lead to harmful chemicals being overlooked. A toxicity-based approach using characterization factors from the USEtox® environmental impact assessment tool was used for this study. Releases of organic and inorganic pollutants to both air and water in Nova Scotia for 2015 were analyzed. Using an ecotoxicity analysis found that the highest priority chemicals identified using the NPRI’s quantity-based approach differed markedly from those identified using the toxicity-based approach. Many of the high-priority chemicals identified using toxicity-based analysis are detrimental to ecosystem health and warrant regulatory attention. The Office of the Auditor General of Canada recently suggested that the Canadian federal government needs to improve control risks of toxic substances. Using a toxicity-based approach may help decision makers in the Canadian federal government effectively control risks of toxic substances and help to inform decision makers, regulators, and Canadians about those risks.
Показать больше [+] Меньше [-]Comprehensive reutilization of iron in iron ore tailings: preparation and characterization of magnetic flocculants Полный текст
2020
Li, Yunyi | Tian, Xiaoyu | He, Xiao | Liu, Yangsheng | Ye, Jiangyu | Wei, Yunmei
A large number of iron ore tailings (IOTs) are produced in steel industry, posing threat to the environment during its storage and disposal. To effectively reutilize Fe in IOTs, we propose a comprehensive utilization scheme: (1) most Fe in IOTs is extracted by concentrated hydrochloric acid to form FeCl₃ flocculants; (2) after separation from the FeCl₃ flocculants, a small amount of Fe is absorbed on the residue solids, which is further washed out to synthesize micron Fe₃O₄ as magnetic seeds. Results show that the as-synthetic FeCl₃ flocculants meet the product standard for FeCl₃ flocculants in China (GB/T 4482-2018) after a series of treatments including rotary evaporation, neutralization, and dilution and have comparable performance with commercial polyaluminum chloride (PAC) and polyaluminum ferric chloride (PAFC). Moreover, the addition of synthetic superparamagnetic Fe₃O₄ (as magnetic seeds) doubled the flocculation rate compared with as-synthetic FeCl₃ flocculants alone. Finally, the reutilization of Fe in IOTs can create a direct economic value of ¥ 1.27/kg IOTs, and produce 745 g high-silicon residues for further reutilization, which indicates that our comprehensive utilization scheme is of great application potential.
Показать больше [+] Меньше [-]Environmental performance, comparative advantage of crude oil and the role of institutional quality Полный текст
2020
Elsalih, Osama | Sertoglu, Kamil | Besim, Mustafa
This study investigates the relationship between environmental performance and the comparative advantage of crude oil by incorporating the role of institutional quality in 28 oil-producing countries from 2002 to 2014. Using dynamic panel data analysis, the results show that environmental performance and institutional quality along with the conventional factors for comparative advantage are key determinants of the comparative advantage of crude oil. Specifically, while environmental performance negatively affects the comparative advantage of crude oil, it is also negatively associated with the comparative advantage of crude oil. These results are in support of the pollution haven hypothesis in resource-based industry, and it shows a bidirectional relationship between environmental performance and comparative advantage of producing crude oil. Further, the results revealed a vital role played by institutional quality in enhancing the comparative advantage of crude oil and environmental performance. More so, the environmental Kuznets curve (EKC) hypothesis is validated in our result. Finally, a substantial difference in the results between OPEC and non-OPEC countries is confirmed by a set of dummy variables.
Показать больше [+] Меньше [-]Characterization of PM2.5 sources in a Belgrade suburban area: a multi-scale receptor-oriented approach Полный текст
2020
Todorović, Marija N. | Radenković, Mirjana B. | Onjia, Antonije E. | Ignjatović, Ljubiša M.
Designated as the most harmful for health, PM₂.₅ aerosol fraction was a subject of our study. It was collected for all four seasons during 2014/15 in the suburban area of Belgrade (Serbia) and analysed for Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, As, Ba and Pb elements and for NH₄⁺, NO₃⁻ and SO₄²⁻ ions by particle-induced X-ray emission and ion chromatography techniques, respectively. Obtained concentrations have been treated by a combination of several receptor-oriented models to reveal source contributions to the suburban PM₂.₅ at different spatial scales. Applied positive matrix factorization analysis indicated five main groups of emission sources: biomass burning (14.5%), traffic (3.9%), regional combustion/secondary sulphates (28.8%), local combustion/secondary nitrates (29.7%) and soil (5.4%). Local heating units had been pointed out as dominant contributors by long-range transport and ground-wind circulation analyses. Air masses circulating over the Balkan Peninsula denoted regional emissions as responsible for the high concentrations of secondary sulphates. Local and long-range transport analyses combined suggested that the BB and the LC/NO₃ originated from the wider urban area. Several Saharan dust episodes were detected as well. Presented results might be a basis for the development of air pollution mitigation strategies in the continental Balkan area, considered one of the most polluted and under-investigated European regions.
Показать больше [+] Меньше [-]Facile fabrication of magnetic phosphorylated chitosan for the removal of Co(II) in water treatment: separation properties and adsorption mechanisms Полный текст
2020
Yuan, Donghai | Zhang, Wenjing | Cui, Jun | He, Liansheng | Wang, Jiazhuo | Yan, Chenling | Kou, Yingying | Li, Junqi
Magnetic phosphorylated chitosan composite (P-MCS), an excellent adsorbent for Co(II), was synthesized in this experiment via a facile fabrication. Its removal efficiency was improved by optimizing pH, contact time, and initial concentration. The adsorption isotherms and kinetic models of Co(II) by P-MCS followed the Langmuir model and the pseudo-second-order model, respectively. However, the rate of adsorption was also affected by intragranular diffusion. The maximum adsorption capacity was 46.1 mg g-1 for Co(II). The results of spectroscopic analysis also indicated that good adsorption performance of Co(II) mainly depends on surface chelation between functional groups and metal ions. The saturation magnetic susceptibilities of P-MCS and P-MCS-Co were 22.29 emu g⁻¹ and 18.18 emu g⁻¹, respectively. The excellent magnetic properties of P-MCS enabled the easy achievement of solid-liquid separation via the use of an external magnetic field. In complex aqueous solutions, K⁺, Na⁺, Ca²⁺, and Mg²⁺ have less influence on P-MCS adsorption Co(II), but the adsorption capacity on Co(II) is still good. This study shows the feasibility of using P-MCS to treat wastewater containing Co(II).
Показать больше [+] Меньше [-]Application of ZnO nanorods doped with Cu for enhanced sonocatalytic removal of Cr(VI) from aqueous solutions Полный текст
2020
Godini, Kazem | Tahergorabi, Mahsa | Naimi-Joubani, Mohammad | Shirzad-Siboni, Mehdi | Yang, Jae-Kyu
The aim of this research was to develop a simple and inexpensive process for reduction of Cr(VI) to Cr(III). Zinc oxide nanoparticles were synthesized with an easy co-precipitation procedure, and the addition of Cu²⁺ doping agent effectively enhanced the Cr(VI) reduction in the presence of ultrasound (US). XRD, FT-IR, FE-SEM, EDX, VSM, and XPS were used to determine the structural specifications of the zinc oxide nanoparticles. Under optimal conditions such as pH 3, initial Cr(VI) content of 20 mg/L, and catalyst dosage of 0.8 g/L, the ultrasonic/Cu–ZnO process showed a higher sonocatalytic activity (96.83%) than ultrasonic/ZnO (67.36%) after 60 min. By increasing pH and Cr(VI) concentration, the removal efficacy of Cr(VI) declined. The experimental data was well described with the first-order kinetic model. When initial Cr(VI) concentration increased from 10 to 50 mg/L, the first-order rate constant declined from 0.2326 to 0.0019 min⁻¹ and electrical energy per order (EEO) enhanced from 19.81 to 2425.26 kWh/m³. Also, the ultrasonic/Cu–ZnO system exhibited considerable sonocatalytic performance in Cr(VI) reduction in the presence of hydrogen peroxide and citric acid, and complete removal was achieved within 60 min. The presence of anions negatively affected Cr(VI) reduction. Complete reduction was attained when ultrasound was applied at a power of 100 W. The catalyst activity was well maintained up to six consecutive cycles. In addition, the removal efficiency was approximately 62 and 65% for field water and real electroplating wastewater samples, respectively.
Показать больше [+] Меньше [-]The modulation of ion homeostasis by silicon in cadmium treated poplar callus cells Полный текст
2020
Kučerová, Danica | Labancová, Eva | Vivodová, Zuzana | Kollárová, Karin
One of the major reasons why cadmium is toxic in plants is because it disturbs their nutrient balance. The aim of this work is to investigate the effects of cadmium (Cd) and/or silicon (Si) on the nutrient status of poplar callus cells after 3 and after 9 weeks of Cd exposure and to study its possible relationship with the changes in the fresh and dry mass, the plasma membrane integrity, and cadmium tolerance patterns. A principal component analysis (PCA) was performed to reveal the associations among the elements, and the variability between both treatments, and between the 3- and 9-week stages. Cadmium reduced the fresh and dry mass, the plasma membrane integrity, and the concentration of all nutrients except for P. After 9 weeks of exposure, the Cd concentration in callus cells had almost doubled, in spite of an improvement in all studied parameters. These changes may be due to the callus acclimatizing to the Cd stress. In the Cd + Si treatment, the fresh and dry mass, the plasma membrane integrity, and the concentration of nutrients, as well as the growth tolerance index, increased in comparison with the Cd treatment. We assumed that the enhancement in the plasma membrane integrity mediated by Si under Cd stress had caused the improvement in the uptake of nutrients and, consequently, the fresh and dry mass of callus cells had increased. The reduction in Cd concentration due to the Si impact also contributed to the increase in fresh and dry mass.
Показать больше [+] Меньше [-]Effective decontamination of As(V), Hg(II), and U(VI) toxic ions from water using novel muscovite/zeolite aluminosilicate composite: adsorption behavior and mechanism Полный текст
2020
Salam, Mohamed Abdel | Abukhadra, Mostafa R. | Mostafa, Merna
Muscovite/phillipsitic zeolite was introduced as a novel inorganic composite of stunning adsorption properties. The composite was investigated in the uptake reactions of Hg(II), As(V), and U(VI) as highly toxic water contaminants considering different adsorption factors. The adsorption properties of muscovite/phillipsitic zeolite are highly dependent on the pH values and the best decontamination percentages can be obtained at pH 4, pH 5, and pH 5 for Hg(II), As(V), and U(VI), respectively. The kinetic studies demonstrated adsorption equilibrium for Hg(II), As(V), and U(VI) after 360 min, 300 min, and 360 min, respectively. The equilibrium modeling suggested monolayer uptake for all the metals and represented mainly by the Langmuir model considering both the values of determination coefficient and chi-squared (χ²). The estimated maximum capacities are 117 mg/g (Hg(II)), 122.5 mg/g (As(V)), and 138.5 mg/g (U(VI)) which are higher values than several studied adsorbents. The Dubinin–Radushkevich adsorption energies of Hg(II) (19.4 kJ/mol), As(V) (25.6 kJ/mol), and U(VI) (26.47 kJ/mol) signify chemical adsorption mechanisms and close to the obtained values for the ion-exchange process. Additionally, the composite is of high reusability properties and was applied effectively for five decontamination cycles. Graphical abstract
Показать больше [+] Меньше [-]How does vertical fiscal imbalance affect environmental pollution in China? New perspective to explore fiscal reform’s pollution effect Полный текст
2020
Huang, Yue | Zhou, Yicheng
Exploring fiscal reform’s pollution effect draws increasing attention. Our paper brings a new perspective, i.e., the vertical fiscal imbalance (VFI) perspective, to study such issue. With the panel data of China’s provincial level from 1999 to 2016, we reveal whether and how VFI affects environmental pollution. We find that VFI significantly enhances the environmental pollution level of China. As the VFI increases, environmental pollution effect caused by VFI appears to be aggravated. According to the transmission path check, we confirm in our paper that VFI can indirectly lead to environmental degradation by affecting the two channels environmental regulation and industrial transformation. Further, through the sub-sample regressions, we find that the impacts of VFI on environmental pollution as well as the transmission paths are regionally heterogeneous. Finally, we believe that using the VFI as a variable to explore fiscal reform’s effect on environment is of rationality, and for a better environmental quality, VFI should be avoided.
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