خيارات البحث
النتائج 5681 - 5690 من 6,489
Human exposure of bisphenol A and its analogues: understandings from human urinary excretion data and wastewater-based epidemiology النص الكامل
2020
Wang, Hao | Liu, Ze-hua | Zhang, Jun | Huang, Ri-Ping | Yin, Hua | Dang, Zhi
This work evaluated human exposure to bisphenol A (BPA) and its analogues based on human urinary excretion data and wastewater-based epidemiology (WBE). The results showed that the world’s average human daily intake ranked from high to low is in order of bisphenol A (BPA), bisphenol F (BPF), bisphenol S (BPS), bisphenol P (BPP), bisphenol AP (BPAP), bisphenol B (BPB), bisphenol Z (BPZ), and bisphenol AF (BPAF), and their corresponding human daily intakes are 2.53, 0.68, 0.60, 0.41, 0.36, 0.29, 0.24, and 0.06 μg/p/day, respectively. BPA is clearly the dominant bisphenol for human exposure. However, the results also showed that humans have been widely exposed to BPA analogues as well. Many BPA analogues showed similar estrogenic activities to those of BPA; therefore, the adverse effects of BPA and its analogues on humans should be comprehensively evaluated. The nominal exposure levels obtained based on wastewater-based epidemiology ranked high to low are in order of BPA (513.73 μg/p/day), BPF (10.20 μg/p/day), BPS (5.21 μg/p/day), BPP (1.15 μg/p/day), BPZ (0.66 μg/p/day), BPB (0.61 μg/p/day), BPAF (0.58 μg/p/day), and BPAP (0.35 μg/p/day). The world’s human average daily intakes of BPA and its analogues are only 0.5–47.9% of the intakes of their corresponding human nominal exposures. This study suggests that other sources rather human excretions are important origins in municipal wastewater, which indicates that the WBE method based on parent compounds is inappropriate for evaluations of human daily intakes of BPA and its analogues, neither for other industrial compounds that have multiple important sources. Three main important sources of BPA and its analogues in municipal wastewater are likely effluents of industrial wastewater, discharges of hospital wastewater, and landfill leachates. To decrease discharges of BPA and its analogues to the natural environment, any mixing of industrial and hospital wastewater as well as landfill leachates in municipal wastewater is not favorable.
اظهر المزيد [+] اقل [-]Evaluation of Culex quinquefasciatus wings asymmetry after exposure of larvae to sublethal concentration of ivermectin النص الكامل
2020
Alves, Stênio Nunes | Pujoni, Diego G. F. | Mocelin, Giovani | Melo, Alan L. | Serrão, José E.
The surviving insects submitted to chemical control have morphological alterations that impact on their mechanisms of resistance and their final development. Those changes are detected and measured using physical features related to symmetry, specifically named fluctuating asymmetry. This is detected when deviations from the perfect bilateral symmetry for specific morphological characteristic is influenced by genetics or environmental stress. Thus, in this paper we analyze the wing in adult of Culex quinquefasciatus (Diptera - Culicidae) after larvae exposure to ivermectin LC₅₀. Three hundred larvae of C. quinquefasciatus were exposed to ivermectin in 1.5 μg/L (LC₅₀) concentration during 30 min, and three hundred larvae were exposed to distilled pure water as control group. For fluctuating asymmetry, adult males and adult females were selected from each group (n = 83) from the untreated group and (n = 79) from treated group. Wings from adults of each group were mounted in glass microscope slides and coverslip in Canada’s balsam and analyzed with a stereomicroscope with a video camera attached. The treatment effect on M₃ ₊ ₄ was marginally significant with higher asymmetry values in the control group. The data obtained here suggest the importance of future experiments to elucidate the mechanisms associated with FA. Moreover, according to the results obtained, it may be suggested that FA is present in females in ornaments, or secondary sexual characters, as an indicator of phenotypic quality of the partners.
اظهر المزيد [+] اقل [-]Nitrous oxide gas emissions estimated by liquid-phase measurements: robustness and financial opportunity in single and multi-point monitoring campaigns النص الكامل
2020
Fenu, Alessio | Wambecq, Tom | de Gussem, Kris | Weemaes, Marjoleine
A liquid-phase nitrous oxide sensor can be used as a proxy to estimate the gas emissions. Experiments conducted in a pilot-scale Anammox reactor, at different degrees of aeration intermittency, indicate a predictive error in the range of 13.4–19.3% during the stripping phase, with a higher error range in the unaerated phases (23.4–62.8%). The total emissions not explained by the aerated model amounted to 14.1%. Only a negligible fraction (3.6%) of the total nitrous oxide emissions were not captured by the unaerated phase model, indicating thus a minor concern for full-scale application. A sensitivity analysis performed on the present study indicates that the quality of the nitrous oxide measurement is of extreme importance to decrease the load prediction uncertainty. Air flow measurement errors have lower impact on the overall load prediction. The financial attractivity of this monitoring approach is significant in completely mixed tank reactors. In presence of a multi-point analysis, and starting from two monitoring points, the financial interest deteriorates by the relatively short lifetime of the commercially available liquid-phase nitrous oxide sensor.
اظهر المزيد [+] اقل [-]Effect of water leaching on biochar properties and its impact on organic contaminant sorption النص الكامل
2020
Schreiter, Inga J. | Schmidt, Wolfgang | Abhay Kumar, | Graber, Ellen R. | Schüth, Christoph
When biochar (BC) is applied to soil, one process that can alter its properties and contaminant sorption is the leaching of minerals and dissolved organic carbon (DOC). This study investigated changes in properties of three BCs (cattle manure, grain husk, and wood chips), due to leaching, and the subsequent impact on sorption of trichloroethylene (TCE) and tetrachloroethylene (PCE). The manure-derived BC released 27.4 mg g⁻¹ DOC, which is over ten times more than that measured for the two plant-based BCs (2.5 and 1.5 mg g⁻¹ DOC for grain husk and wood chips, respectively). In all leachates, potassium is the dominant cation, whereas chloride, sulfate, and phosphate are the main anions. In total, the manure-derived biochar released the highest sum of total ions (73.1 mg g⁻¹), followed by BC produced from grain husk (15.5 mg g⁻¹) and wood chips (1.2 mg g⁻¹). Leaching increased external surface area, mesopore volume, and hydrophobicity of the manure-derived BC and decreased its polarity. This enhanced sorption via partitioning. In plant-based BCs, micropore volume and size distribution were altered, most likely through the un-blocking of pores, causing increased sorption via pore-filling for both TCE and PCE. The results indicate that, depending on feedstock material, BC leaching can alter the environmental fate of organic compounds.
اظهر المزيد [+] اقل [-]Melatonin protects sperm cells of Capoeta trutta from toxicity of titanium dioxide nanoparticles النص الكامل
2020
Özgür, Mustafa Erkan | Ulu, Ahmet | Noma, Samir Abbas Ali | Özcan, İmren | Balcıoğlu, Sevgi | Ateş, Burhan | Köytepe, Süleyman
In this study, it was aimed to determine the protective effects of melatonin (0.01, 0.1, and 1 mM) against 10 mg/L titanium dioxide nanoparticles (TiO₂-NPs) on kinematic and oxidative indices in the sperm cells of Capoeta trutta. Therefore, TiO₂ nanoparticles were synthesized primarily within the scope of the study. The synthesized nanoparticles were characterized by structurally different techniques. Then, melatonin and TiO₂ were applied to Capoeta trutta sperm cells by in vitro. According to our data, all doses of melatonin showed protective effects on all velocities of sperm cells such as the straight line velocity (VSL), the curvilinear velocity (VCL), and the angular path velocity (VAP) against TiO₂-NPs, while 0.1 and 1 mM doses of melatonin improved the VSL value. Although TiO₂-NPs increased total glutathione (tGSH), malondialdehyde (MDA) lipid peroxidation, and superoxide dismutase (SOD) compared to the control group, there were positive treatment effects for all doses of melatonin on antioxidant capacity of sperm cells. At the end of this research, it is suggested that over 0.1 mM dose of melatonin improves the velocity of sperm cells and it plays a protective role against the toxic effects of TiO₂-NPs.
اظهر المزيد [+] اقل [-]The financial development-environmental degradation nexus in the United Arab Emirates: the importance of growth, globalization and structural breaks النص الكامل
2020
Shahbaz, Muhammad | Haouas, Ilham | Sohag, Kazi | Ozturk, Ilhan
This article revisits the nexus between financial development and environmental degradation by incorporating economic growth, electricity consumption and economic globalization in the CO₂ emissions function for the period 1975QI–2014QIV in the United Arab Emirates. We apply structural break and cointegration tests to examine unit root and cointegration between the variables. Further, the article also uses the Toda-Yamamoto causality test to investigate the causal relationship between the variables and tests the linkages of the robustness of causality by following the innovative accounting approach. Our empirical analysis shows cointegration between the series. Financial development increases CO₂ emissions. Economic growth is positively linked with environmental degradation. Electricity consumption improves environmental quality. Economic globalization affects CO₂ emissions negatively. The relationship between financial development and CO₂ emissions is U-shaped and inverted N-shaped. Further, financial development leads to environmental degradation, and environmental degradation in turn leads to financial development in the Granger sense.
اظهر المزيد [+] اقل [-]Cooperative identification for critical periods and critical source areas of nonpoint source pollution in a typical watershed in China النص الكامل
2020
Ruan, Shuhe | Zhuang, Yanhua | Hong, Song | Zhang, Liang | Wang, Zhen | Tang, Xianqiang | Wen, Weijia
Critical periods (CPs) and critical source areas (CSAs) refer to the high-risk periods and areas of nonpoint source (NPS) pollution in a watershed, respectively, and they play a significant role in NPS pollution control. The upstream Daning River Basin is a typical watershed in the Three Gorges Reservoir area. In this study, a Hydrological Simulation Program-Fortran (HSPF) model was used to simulate phosphorus loss in the upstream Daning River Basin. Co-analysis of critical periods and critical source areas (CACC) is a quantitative collaborative analysis method for the identification of CSAs in CPs, and it was used to classify the periods and areas of NPS pollution as CPs, sub-CPs, non-CPs, CSAs, and non-CSAs. The CPs occurred in months 5–7 and accounted for 53.7% of the total phosphorus (TP) loads, and the sub-CPs occurred in months 1, 3, 4, and 8 and accounted for 29.2% of the TP loads. In CSAs, 49.4% of the TP loads occurred in 26.8% of the basin. Furthermore, we proposed the following multilevel priority control measure for NPS pollution in the upstream Daning River Basin: CSAs in CPs (with load-area rate of 1.4), CSAs in sub-CPs (0.7), CSAs in non-CPs (0.4), non-CSAs in CPs (0.3), non-CSAs in sub-CPs (0.2), and non-CSAs in non-CPs (0.1). CSAs in CPs accounted for 25.8% of the TP loads from 19.0% of the areas in only 3 months while 49.4% of the TP loads from similar areas over an entire year. These findings indicated that the CSAs in CPs located in farmland along the Daning, Dongxi, and Houxi Rivers should be prioritized for pollution management measures.
اظهر المزيد [+] اقل [-]Preparation, characterization, and Cd(II) sorption of/on cysteine-montmorillonite composites synthesized at various pH النص الكامل
2020
Hu, Zhao | Hu, Hongqing | Song, Mengdie | Danru, | Huang, Guoyong | Zuo, Jichao
Montmorillonite-cysteine could be used as the immobilizer, detector, and detoxifier of heavy metals. To further the understanding and the application, the interaction between the montmorillonite and cysteine and the adsorption of cysteine on montmorillonite and characterization of the composites need to be studied further. In present work, the effects of pH, contact time and initial concentration of cysteine on the adsorption, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Cd(II) adsorption on the composites were conducted to characterize the composites synthesized at different pH conditions. The results showed that the adsorption amount of cysteine on montmorillonite decreased with the increase of pH in the range of 2.4–8.0, reached equilibrium in about 1 min and increased with the initial concentration of cysteine and reached the maximum at 160 mg/g. The adsorption data fitted with Langmuir better than Freundlich, fitted with first-order and second-order better than the intraparticle diffusion model. XRD patterns and FTIR spectra showed that the interlayer spacing of the composite synthesized in the range of pH 2.4–4.3 was larger than that at pH 4.5–8.0 and the bonding of cysteine and montmorillonite mainly depended on the action of the amino group. Adsorption of Cd(II) on composites indicated more cysteine loaded (pH < 4.5) composite had greater capacity for Cd(II). The above results demonstrated that the composite synthesized under lower pH could retain more active cysteine, which might be beneficial to its various applications.
اظهر المزيد [+] اقل [-]Can integrated rice–duck farming reduce CH4 emissions? النص الكامل
2020
Wang, Wei | Wu, Xiaohong | Deng, Zhengmiao | Yin, Chunmei | Xie, Yonghong
Integrated rice–duck farming (IRDF) has proven to decrease methane (CH₄) emissions due to increased dissolved oxygen caused by duck bioturbation. The duck bioturbation, however, also causes many bubbles of CH₄ that were overlooked in previous studies. Therefore, it is uncertain whether IRDF could decrease CH₄ emissions. We hypothesize that the effect of IRDF on CH₄ emissions is related with the intensity of duck bioturbation. We simulated duck’s disturbance (trampling and foraging) by stirring and aerating the surface soil in flooded rice fields. Three treatments were disturbed with an interval of 12 h (D12), 24 h (D24), and 48 h (D48), respectively, with non-disturbance as the control (CK). CH₄ emissions as bubbles during the disturbance period (CH₄-A) were investigated. Besides, CH₄ emissions were investigated every 2 h (CH₄-B), which lasted for 4 days during the rice elongation stage. Compared with CK, D12, D24, and D48 decreased CH₄-B emissions by 17.1%, 14.0%, and 10.1%, respectively. However, the CH₄-A emissions under D12, D24, and D48 were equivalent to 14.2%, 14.0%, and 11.9% of CH₄ emissions under CK, respectively. On the whole, simulated duck bioturbation had limited effects on the reduction of total CH₄ emissions.
اظهر المزيد [+] اقل [-]Nigerian foods of probiotics relevance and chronic metal exposure: a systematic review النص الكامل
2020
Orisakwe, Orish Ebere | Amadi, Cecilia Nwadiuto | Frazzoli, Chiara | Dokubo, Awolayeofori
Probiotics are functional foods with a wide armamentarium of health benefits in man including metal chelation. Given the unacceptable blood lead levels and the near ignorance or negligence of heavy metals in both diagnoses and management of diseases in Nigeria, it is feared that these metals are involved in the aetiogenesis of several ailments from preeclampsia, metabolic syndrome, cancer, etc. This is an insight on Nigerian fermented foods and their possible role as metal chelators in the management of the chronic heavy metal exposure in Nigeria. One hundred and five articles fulfilled the inclusion criteria. Google scholar, PubMed and SCOPUS were searched for articles reporting fermented foods and probiotics in Nigeria. Only studies published in English Language were included, but there was no limitation in year of study. One hundred and five articles fulfilled the inclusion criteria. Studies from some African countries suggest that fermented foods of probiotics relevance have effectively shown metal chelation properties. Consumption of Nigerian fermented foods may hold a promise in checking the high body burden of heavy metals in Nigeria. Graphic abstract
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