Results 1 - 10 of 646
Results 1 - 10 of 646. Search took: 0.021 seconds
|Sort by: date | relevance|
[en] The present study explores the impact of economic growth; urban expansion; and consumption of fossil fuels, solid fuels, and renewable energy on environmental degradation in developing economies of Sub-Saharan Africa. To demonstrate its findings in detail, the study adopts a system generalized method of moment (GMM) on a panel of 34 emerging economies for the period from 1995 to 2015. The results describe that the consumption of fossil and solid fuels for cooking and expansion of urban areas are significantly contributing to carbon dioxide emissions, on one end, and stimulating air pollution, on the other. The results also exhibit an inverted U-shape relationship between per capita economic growth and carbon emissions. This relation confirms the existence of an environmental Kuznets curve (EKC) in middle- and low-income economies of Sub-Saharan Africa. Furthermore, the findings reveal that the use of renewable energy alternatives improves air quality by controlling carbon emissions and lowering the direct interaction of households with toxic gases. Thus, the use of renewable energy alternatives helps the economies to achieve sustainable development targets.
[en] This study investigated arsenic (As) availability and uptake by rape (Brassica campestris L.) during two harvest periods of carboxymethyl cellulose (CMC)-stabilized ferrihydrite (HFO) nanoparticles for in situ treatment As-contaminated soil. Application of modified HFO nanoparticles in soils not only provided a larger specific surface area but also markedly improved stability against aggregation and recrystallization. For 90-day incubation, bare HFO particles were gradually converted to the crystalline Fe(III) oxide form, although this was not observed for the 0.5% CMC-HFO nanoparticles. CMC-modified HFO nanoparticles could be more effective in lowering the As uptake by rape and available As in soils than bare HFO particles. Compared the control without amendments, As contents in rape and available As in soils decreased 69.7 and 59.0%, respectively, during the second harvest when soils were amended with 0.5% HFO nanoparticles. And the soil-solution distribution coefficient (Kd) increased by 2.6 and 2.8 times for the first and second harvest. Furthermore, the ratio of amorphous and free Fe-oxides (Feo/Fed) showed significant negative linear correlations with Asplant (P < 0.01), available As (P < 0.05), and nonspecifically sorbed As in soil (P < 0.01). In contrast, Feo/Fed was positively correlated with Kd and amorphous crystalline Fe/Al oxide-sorbed As, which suggests that a larger amount of As is associated with Fe(hydr)oxide in the amorphous phase or smaller particles.
[en] Many agricultural soils in Egypt irrigated with untreated wastewater. Herein, we investigated the effect of untreated industrial wastewater irrigation on the soil and fodder plant Corchorus olittorius (Jew mallow). It also aimed to assess its effect on the growth measurements as well as analyses of soils, irrigation waters, and plants for heavy metal and nutrient concentrations. Significant differences between irrigation waters and soil irrigated with fresh and wastewater were recognized. Wastewater irrigation leads to remarkable reduction in the growth parameters and reduced its vegetative biomass. The concentration of Pb, Cd, Cr, Cu, Fe, and Zn were high significant and above phytotoxic concentrations in leaves (edible part) and roots of wastewater-irrigated plant. The present study indicated that Jew mallow plant tends to phytostabilize (Cd, Ni, and Mn) in its root and had the ability to translocate (Pb, Cu, Cr, Fe, and Zn) to its leaves. Higher concentrations of Cd, Cu, Cr, Pb, Fe, Mn, Ni, and Zn in the roots than leaves indicate that the roots are hyper-accumulators for Pb, Cr, Cu, Fe, and Zn more than the leaves. The research study recommended that there is a need to protect the soil from contamination through regular monitoring and not to cultivate Jew mallow in wastewater-irrigated soil and that it had a high capacity to accumulate heavy metals in its edible part and causes several harmful health effects for consumers.
[en] The graphene (GR)/TiO2 membrane was prepared by the sol-gel method and coated on the indium tin oxide (ITO) conductive glass, which showed high and stable photo(-electro)-catalytic activities to rhodamine B (Rh-B) in water. Characterization results showed that the GR was dispersed and wrapped in the needle-like TiO2. With GR/TiO2 membrane and simulated sunlight irradiation, the removal efficiency of Rh-B (10 mg l−1 and pH at 5.4) arrived at 87.6% within 300 min. However, the higher removal efficiency for Rh-B reached to 97.8% by the photo-electro-catalytic degradation with the applied voltage 4 v for 30 min. The ·OH that generated in the photo-catalytic degradation process were responsible for Rh-B decomposition. The ·O2− played the significant role in the photo-electro-catalytic degradation of Rh-B. Furthermore, the decarboxylation was also occurred in the photo-electro-catalytic degradation for the Rh-B in water except for the deethylation and hydroxylation in the photo-catalytic degradation. In addition, the toxicities of the intermediates were calculated using the ECOSAR program and the EPIWIN software. The results indicated that the toxicities of intermediates from photo-electro-catalytic degradation for the Rh-B were higher than photo-catalytic degradation, due to the generation of decarboxylate.
[en] Nitrogen (N) can alleviate metal toxicity. However, as of yet, there have been no studies showing the efficacy of NO3−/NH4+ in mitigating Cu toxicity. The objective of this study was to evaluate the Cu toxicity on the nutritional and productive attributes of Panicum maximum cv. Tanzania as well as the role of NO3− and NH4+ ratios in nutritional homeostasis. The experiment was conducted using 3 × 4 factorial treatments arranged in a randomized complete block design with three replicates. The treatments were three NO3−/NH4+ ratios (100/0, 70/30, and 50/50) and four Cu rates (0.3, 250, 500, and 1000 μmol L−1) in nutrient solution. Copper concentrations in the diagnostic leaves (DL) were highest in plants grown under 70/30 NO3−/NH4+ ratios and a Cu rate of 1000 μmol L−1. In this combination, it was observed that DL had higher concentrations of NH4+, greater glutamine synthetase activity, lower chlorophyll concentration (SPAD value), and lower shoot dry mass, suggesting high disorders of nutritional homeostasis. Plants receiving N in the form of NO3− and 1000 Cu μmol L−1 showed that DL had lower concentrations of Cu, higher concentration of chlorophyll, higher NO3− concentration, higher nitrate reductase activity, and higher NO3− accumulation in the roots, suggesting a reduction in disorders of nutritional homeostasis. The disorders on mineral uptake, N assimilation, and biomass production caused by Cu toxicity are shown to be affected by NO3−/NH4+ ratios, and N supply via NO3− allowed for better homeostasis of the forage grass.
[en] Carbon nanotubes (CNTs)/agarose (AG) membrane on the ITO (indium tin oxide) conductive glass, with high efficiency of electrocatalytic degradation for rhodamine B (Rh-B) in water, was prepared using an easy and green method. The prepared CNTs/AG membrane was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectra (EDS), infrared spectroscopy (IR), and electrochemical impedance spectroscopy (EIS). The results revealed that CNTs were dispersed in the AG membrane. Additionally, the electrocatalytic activities for Rh-B were conducted on the electrochemical workstation with a three-electrode system. Both initial pH and potential played an important role in the process of electrocatalytic degradation. At pH 3 and potential reaching 4 V, the removal rate of Rh-B (10 mg/L) in water achieved 96% within 20 min. The stability of the prepared CNTs/AG membrane was also investigated. Besides, the toxicities of the main intermediates from the electrocatalytic degradation for Rh-B were calculated using the ECOSAR program and EPIWIN software, and results indicated that the toxicities of some intermediates were higher than those of the parent pollutant (Rh-B). These findings provided a light-spot to simplify the preparation of efficient working electrode and emphasized the possible potential risks from intermediates at the same time.
[en] Graphene has been used in several fields covering from electronics to biomedicine, especially exhibiting a widespread variety of promising biological and biomedical applications. In the past decade, the biomedical applications of graphene have attracted much interest. However, the effect of pristine graphene (pG) toxicity in aquatic vertebrates has not been fully studied. Thus, in this study, the toxicity of pG was experimentally evaluated using developing zebrafish embryos as in vivo model system. To determine this, 4-hpf embryos were exposed to different concentrations of pG (1, 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 μg/L) and different early life-stage parameters were observed at 24, 48, 72, and 96 hpf. Through embryogenesis, pG was observed to induce significant embryonic mortality, delayed hatching, heartbeat, several morphological defects, pericardial toxicity, and bradycardia. Yolk sac edema and pericardial edema were induced by pG in developing embryos. These outcomes would provide new insights into the adverse effects of pG on the developing embryonic cardiac defects in vertebrates and highlight the probable natural environment and health hazards of pG flakes.
[en] Although intensive marine fish farming is often assumed to be eco-friendly, the associated activity can lead to chronic exposure of marine organisms to potentially toxic discharges. Moreover, despite the increasing popularity of integrated multi-trophic aquaculture (IMTA), studies of the effects of fish farm effluents are almost non-existent. In the present study, the changes in the toxic potential of effluents from five land-based marine fish farms in NW Spain subjected for different lengths of time to a biodegradation procedure (for 0, 48, 120, and 240 h) were assessed in a battery of bioassays including organisms from different trophic levels (Vibrio fischeri, Isochrysis galbana, and Paracentrotus lividus). The results of the bioassays at the different times were then considered together with farm water flow in the Potential Ecotoxic Effects Probe (PEEP) index. Despite the high volumes of effluents discharged, the generally low toxicity of the effluents hinders assessment of potentially toxic effects. However, dose–response curves and statistical analysis demonstrated the existence of toxic effects during the first five days of the biodegradation procedure, especially immediately after sampling. The proposed modification of the PEEP index better reflects the changes in toxicity over time. .
[en] Floating catalytic chemical vapor deposition technique was used for synthesizing carbon nanotubes (CNTs) using ferrocene in benzene as the hydrocarbon source. The functionalization of CNTs was carried out by oxidation followed by grafting of potassium iodide (KI) and mercaptoethanol (HS(CH2)2OH) ligands to produce iodide-grafted CNTs (CNT-I) and thiol-functionalized CNTs (CNT-SH), respectively. The resulting adsorbents have been thoroughly characterized by various techniques. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) studies revealed the efficient grafting of the ligands. Further, their adsorption capacities towards antimonite have been assessed. The adsorption kinetics fitted the pseudo-second-order model for both the adsorbents. Moreover, the adsorption of Sb(III) followed Langmuir and Freundlich’s model. The maximum adsorption capacity of CNT-I and CNT-SH for Sb(III) at pH 7 was found to be 200 and 140.85 mg/g, respectively. The interference effect of various ions on the adsorption of antimonite was studied. A suitable mechanism for Sb(III) adsorption has been postulated using TEM, XRD, XPS, and FTIR. The adaptability of the adsorbents was demonstrated by the removal capacity of Sb(III) at parts per billion levels from nuclear decontamination formulation (NAC) and tap water matrix as well.
[en] Di(isononyl)cyclohexane-1,2-dicarboxylate (DINCH) is a plasticizer used in polyvinyl chloride (PVC) products, such as toys and food packaging. Because the use of DINCH is on the rise, the risk of human exposure to this chemical may likewise increase. Discovering markers for assessing human chemical exposure is difficult because the metabolism of chemicals within humans is complex. In this study, two mass spectrometry (MS)-based metabolite profiling data processing methods, the mass defect filter (MDF) method and the signal mining algorithm with isotope tracing (SMAIT) method, were used for DINCH metabolite discovery, and 110 and 18 potential DINCH metabolite signal candidates were discovered, respectively, from in vitro DINCH incubation samples. Of these, the 21 signals were validated as tentative exposure marker signals in a rat model. Interestingly, the two methods generated rather different sets of DINCH exposure markers. Five of the 21 tentative exposure marker signals were verified as the probable DINCH structure-related metabolite signals based on their MS/MS product ion profiles. These five signals were detected in at least one human urine sample. Of the five probable DINCH structure-related metabolite signals, two novel signals might be suitable exposure markers that should be further investigated for their application in human DINCH exposure assessments. These observations indicate that the MDF and SMAIT methods may be used to discover a relatively different set of potential DINCH exposure markers.