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Resultados 2641-2650 de 4,921
Degradation of Paracetamol Adsorbed on Inorganic Supports Under UV Irradiation
2019
Baeza, Patricio | Aballay, Paulina | Matus, Camila | Camú, Esteban | Fernanda Ramirez, M. | Eyzaguirre, Johanna | Ojeda, Juan
The purpose of this piece of work is to study the process of adsorption of paracetamol on activated carbon, silica and alumina and their degradation using UV radiation. The results demonstrate a higher adsorption of paracetamol on alumina and activated carbon, while a minor value was observed in the case of silica. The H-bonding and π-stacking interactions between paracetamol and supports can be explained by the variation in the adsorption capacity values. When the paracetamol adsorbed was irradiated with two different UV irradiance values (59.78 mW cm⁻² and 119.56 mW cm⁻²) for 120 min, the higher degradation percentage was observed on activated carbon with a value of 79%. In the case of alumina and silica, the maximum percentages obtained were 65% and 77%, respectively. The incorporation of H₂O₂ in the reaction medium increases the rate of degradation, mainly at higher irradiance, reaching the maximum values in less time.
Mostrar más [+] Menos [-]Analysis of Changes of Particle Size Distribution and Biological Composition of Flocs in Wastewater During the Growth of Algae
2019
Garbowski, Tomasz | Richter, Dorota | Pietryka, Mirosława
The process of growth of algae can be described using the images from microscopic analysis. The new approach to assessment of the growth dynamics of algae used the data of granulometric composition of liquid medium and the modified Avrami equation relating to the crystallisation process. This paper presents a comparison of both methods (granulometric and microscopic) for the analysis of the dynamics of changes in the growth of algae in wastewater. The experimental set-up consisted of four glass tanks filled with biologically treated sewage, in which algae grew. The cultivation of algae was carried out for 8 weeks. During this period, the granulometric analysis and microscopic observations of sewage were conducted. The study demonstrated that with increase in the size of flocs in treated sewage, biomass of algae was also increased. Therefore, the results obtained with the method of laser diffraction are in agreement with microscopic observation of flocs. Granulometric analysis could be, next to microscopic analysis, a method for the estimation of the dynamics of changes in the growth of algae in sewage. This knowledge will allow to selection of a suitable method of wastewater treatment and algal separation.
Mostrar más [+] Menos [-]Urinary metabolites of polycyclic aromatic hydrocarbons in pregnant women and their association with a biomarker of oxidative stress
2019
Lou, Xiang-Yin | Wu, Peng-Ran | Guo, Ying
Exposure to polycyclic aromatic hydrocarbons (PAHs) during pregnancy may pose adverse health risk to both the mothers and babies. In the present study, 188 pregnant women of different trimesters were recruited in Guangzhou, south China, and nine hydroxyl PAHs (OH-PAHs) and a biomarker of DNA oxidative damage, 8-hydroxy-2′-deoxyguanosine (8-OHdG), were determined in their urine samples. All OH-PAHs except for 4-hydroxyphenanthrene and 6-hydroxychrysene were found in > 90% samples, with total concentration in the range of 0.52 to 42.9 μg/g creatinine. In general, concentration levels of OH-PAHs in pregnant women were lower than those in general population in the same research area but with higher levels in working women than in housewives. The mean daily intakes of PAHs from dietary estimated by urinary OH-PAHs were 0.021, 0.004, 0.047, and 0.030 μg/kg_bw/day for naphthalene, fluorene, phenanthrene, and pyrene, respectively, which were much lower than the reference doses (20, 30, and 40 μg/kg_bw/day for naphthalene, pyrene, and fluorene, respectively) derived from chronic oral exposure data by the United States Environmental Protection Agency. The low exposure levels of PAHs may be attributed to the traditional dietary taboo of Chinese pregnant women, which is to minimize the consumption of “toxic” food. The concentrations of 8-OHdG (4.67–49.4 μg/g creatinine) were significantly positively correlated with concentrations of several OH-PAHs, such as metabolites of naphthalene, fluorene, and phenanthrene (r = 0.3–0.6). In addition, the concentrations of 8-OHdG were higher in working women than in housewives when exposed to the same levels of PAHs, partly indicating the possible relation between work-related pressure for working women and the oxidative stress.
Mostrar más [+] Menos [-]Ginkgo biloba attenuates aluminum lactate-induced neurotoxicity in reproductive senescent female rats: behavioral, biochemical, and histopathological study
2019
Verma, Sonia | Ranawat, Pavitra | Sharma, Neha | Nehru, Bimla
Extensive use of aluminum (Al) in industry, cooking utensils, and wrapping or freezing the food items, due to its cheapness and abundance in the environment, has become a major concern. Growing evidence supports that environmental pollutant Al promotes the aggregation of amyloid beta (Aβ) in the brain, which is the main pathological marker of Alzheimer’s disease (AD). Further, AD- and Al-induced neurotoxic effects are more common among women following reproductive senescence due to decline in estrogen. Though clinically Ginkgo biloba extract (GBE) has been exploited as a memory enhancer, its role in Al-induced neurotoxicity in reproductive senescent female rats needs to be evaluated. Animals were exposed to intraperitoneal dose (10 mg/kg b.wt) of Al and oral dose (100 mg/kg b.wt.) of GBE daily for 6 weeks. A significant decline in the Al-induced Aβ aggregates was observed in hippocampal and cortical regions of the brain with GBE supplementation, as confirmed by thioflavin (ThT) and Congo red staining. GBE administration significantly decreased the reactive oxygen species, lipid peroxidation, nitric oxide, and citrulline levels in comparison to Al-treated rats. On the contrary, a significant increase in the reduced glutathione, GSH/GSSG ratio as well as in the activities of antioxidant enzymes was observed with GBE administration. Based on the above results, GBE prevented the neuronal loss in the hippocampus and cortex, hence caused significant improvement in the learning and memory of the animals in terms of AChE activity, serotonin levels, Morris water maze, and active and passive avoidance tests. In conclusion, GBE has alleviated the behavioral, biochemical, and histopathological alterations due to Al toxicity in rats. However, molecular studies are going on to better understand the mechanism of GBE protection against the environmental toxicant Al exposure. Graphical abstract .
Mostrar más [+] Menos [-]Coconut Shell Activated Carbon as Solid-Phase Extraction Adsorbent for Preconcentration of Selected Pesticides from Water Samples
2019
Kumrić, Ksenija | Vujasin, Radojka | Egerić, Marija | Petrović, Đorđe | Devečerski, Aleksandar | Matović, Ljiljana
Solid-phase extraction (SPE) on activated carbon derived from coconut shell (CSAC) for the preconcentration of four varying polarity pesticides (imidacloprid, acetamiprid, simazine, and linuron) prior to their determination using high performance liquid chromatography with diode array detector (HPLC-DAD) was investigated. The characteristics of the CSAC were analyzed through X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and Brunauer-Emmett-Teller (BET) method. The effects of the solution pH, eluent type, eluent volume, and flow rate were investigated for optimization of the presented procedure. The adsorption was achieved quantitatively on the CSAC column in the pH range of 2.0–7.0, and then the retained pesticides were eluted with dichloromethane. The detection limit was found to be 0.025–0.039 μg L⁻¹, depending on the pesticide. The proposed SPE-CSAC method was used to determine selected pesticides in tap water samples. The recoveries ranged from 58.2 to 105.3%, with low relative standard deviations. The obtained results indicated that the CSAC could be efficiently used as a low cost alternative to commercially available SPE adsorbents for the determination of the varying polarity pesticides in environmental water samples at trace levels.
Mostrar más [+] Menos [-]Ambient air pollution and risk of type 2 diabetes in the Chinese
2019
Li, Hui | Duan, Donghui | Xu, Jiaying | Feng, Xiaoqi | Astell-Burt, Thomas | He, Tianfeng | Xu, Guodong | Zhao, Jinshun | Zhang, Lina | You, Dingyun | Han, Liyuan
We performed a time series analysis to investigate the potential association between exposure to ambient air pollution and type 2 diabetes (T2D) incidence in the Chinese population. Monthly time series data between 2008 and 2015 on ambient air pollutants and incident T2D (N = 25,130) were obtained from the Environment Monitoring Center of Ningbo and the Chronic Disease Surveillance System of Ningbo. Relative risks (RRs) and 95% confidence intervals (95% CIs) of incident T2D per 10 μg/m³ increases in ambient air pollutants were estimated from Poisson generalized additive models. Exposure to particulate matter < 10 μm (PM₁₀) and sulfur dioxide (SO₂) was associated with increased T2D incidence. The relative risks (RRs) of each increment in 10 μg/m³ of PM₁₀ and SO₂ were 1.62 (95% CI, 1.16–2.28) and 1.63 (95% CI, 1.12–2.38) for overall participants, whereas for ozone (O₃) exposure, the RRs were 0.78 (95% CI, 0.68–0.90) for overall participants, 0.78 (95% CI, 0.69–0.90) for males, and 0.78 (95% CI, 0.67–0.91) for females, respectively. Exposure to PM₁₀ and SO₂ is positively associated with T2D incidence, whereas O₃ is negatively associated with T2D incidence.
Mostrar más [+] Menos [-]Application of modified receptor model for soil heavy metal sources apportionment: a case study of an industrial city, China
2019
Li, Yufeng | Zhao, Zhongqiu | Yuan, Ye | Zhu, Peitian | Li, Xuezhen | Guo, Anning | Yang, Qiao
As we all know, geochemical data usually contain outliers and they are heterogeneous, which will severely affect the use of receptor models based on classical estimates. In this paper, an advanced modified RAPCS-RGWR (robust absolute principal component scores-robust geographically weighted regression) receptor model was introduced to analyze the pollution sources of eight heavy metals (Cd, Hg, As, Pb, Ni, Cu, Zn) in a city of southern China. The results showed that source identification and source apportionment are more consistent by this advanced model even though the soil types and farming patterns are diverse. Moreover, this model decreased the occurrence of negative values of the source contribution. For these reasons, the pollution sources were classified into five types by the new model in the study area: agricultural sources, industrial sources, traffic sources, comprehensive sources, and natural sources. (1) The contributions of agricultural sources to Cr and Ni were 243.36% and 242.61%, respectively; (2) the contribution of industrial sources to Cd was 79.25%; (3) the contribution of traffic sources to Cu was 100.31%; (4) the contributions of comprehensive sources to Hg, Pb, and Zn were 253.90%, 242.31%, and 93.32%, respectively; and (5) the contribution of natural sources to As was 208.21%. Overall, the RAPCS-RGWR receptor model improved the validity of the receptor models. It is of great realistic significance to understand and popularize the advanced model in soil source apportionment in agricultural land.
Mostrar más [+] Menos [-]Antecedents of satisfaction and engagement of low-carbon bicycle-sharing using in China
2019
Ding, Xiping | Long, Xingle | Li, Liang | Liang, Hui | Wang, Qingling | Cai, Sijia
Transport sector contributed numerous carbon emissions in China. It is important to promote low-carbon bicycle-sharing using in China. This paper aims to analyze the influencing factors of the satisfaction and engagement of bicycle-sharing in China. An extended model of customer satisfaction is established, which considers both customer satisfaction theory and customer engagement theory. We explore the different effect of convenience, health, safety, and facility on satisfaction of bicycle-sharing using. We also explore the role of satisfaction on three different dimensions of engagement: enthusiasm, participation, and social interaction. Multi-group structure equation model is employed to explore the different roles of gender on the determinants of satisfaction and engagement of bicycle-sharing using. The findings reveal that facilities had the larger effect on satisfaction of bicycle-sharing using than safety and health for male. Safety had the largest influence on satisfaction of bicycle-sharing using for female, followed by facility, convenience, and health.
Mostrar más [+] Menos [-]Impact of Dairy Manure Processing Using Polyacrylamide on Antibiotic-Resistant Bacterial Level
2019
Han, Sunghwa | Long, Sharon C. | Runge, Troy | Dong, Cuihua | Liu, Zong
This study investigates levels of bacteria through population indicators as well as the levels of antibiotic-resistance bacteria in dairy manure. Although overall bacteria levels may be reduced during manure processing, it is of interest whether changes in management practices could lead to increased levels of antibiotic-resistance bacteria, which are becoming more prevalent in agricultural soils, groundwater, and surface water. Appropriate manure treatments are needed not only to reduce the potential risk of exporting antibiotic-resistant bacteria to an environment, but also reduce antibiotic-resistant bacteria exposure to animals if processed water is recycled. Results from this research revealed manure separation under relatively low speed centrifuge with 100 ppm polyacrylamide (PAM) emulsion addition reduced bacteria indicators population such as total coliforms and Escherichia coli (E. coli) significantly in the liquid stream compared to no PAM added. However, the percentages of antibiotic-resistant isolates in liquid stream after centrifuge with PAM were higher compared to raw manure and no PAM added. Antibiotic resistance (cephalosporin, florfenicol, penicillin, or tetracycline) was observed or 65.38% of bacterial isolates in manure from a large dairy farm in Wisconsin and 39.29% of isolates demonstrated multidrug resistance. The results from this study strongly suggest that appropriate manure treatment is essential in order to help minimize the abundance of antibiotic resistance in our water environment.
Mostrar más [+] Menos [-]Acid-Generating Waste Rocks as Capillary Break Layers in Covers with Capillary Barrier Effects for Mine Site Reclamation
2019
Larochelle, Chloé G. | Bussière, Bruno | Pabst, Thomas
Tailings and waste rocks can be used to build covers with capillary barrier effects (CCBE) for the purposes of reclaiming acid-generating waste storage facilities while enhancing the value of the materials available on site. The efficiency of non-acid generating tailings, desulfurized tailings, and non-reactive waste rocks as cover materials was demonstrated in previous laboratory and field studies. However, acid-generating waste rocks are usually not considered for cover construction because of the risk of contamination. Nonetheless, using acid-generating waste rocks as the bottom capillary break layer in a CCBE could have economic and logistical benefits for companies, including helping to reduce the volume of waste rock piles and to valorize material that are generally considered to be problematic. In this study, laboratory column tests were performed to evaluate cover scenarios using acid-generating waste rocks from Westwood-Doyon mine (Québec, Canada). These waste rocks were placed under a moisture-retaining layer made of desulfurized tailings. A column test with non-acid-generating waste rocks was also performed for comparison purposes. Columns were submitted to eight wetting/drainage cycles. The performance of these systems was assessed by monitoring the volumetric water content in the different layers and by analyzing the water quality of the leachates. Significant reductions in contamination were observed when covers were added on the reactive waste rocks. These results suggest that it could be possible to valorize acid-generating waste rocks in cover systems.
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