خيارات البحث
النتائج 1921 - 1930 من 4,291
The Kinetic Study of Cesium, Strontium, and Rubidium Radionuclide’s Adsorption from Synthetic and Natural Wastes via the Mag-molecular Process
2017
In this study, the adsorption kinetic of cesium, strontium, and rubidium radionuclides was investigated using ferritin magnetic molecules. Kinetic investigation of synthetic and natural wastes was carried out and the results were compared. Pseudo first-order, pseudo second-order, Elovich, double-exponential, and intraparticle diffusion models were the kinetic models used in the fitting of experimental data. The kinetic study of synthetic waste revealed that the double-exponential model demonstrated excellent fitting. Coefficient of determination resulting from fitting of cesium, strontium, and rubidium radionuclide’s adsorption results via the double-exponential model are 0.9938, 0.9905, and 0.9863, respectively. In the experiments conducted on natural wastes, too, all of the five kinetic models were investigated. Results indicated that the double-exponential model matched greatly with the experimental data, and cesium, strontium, and rubidium radionuclide’s coefficients of determination were 0.9742, 0.9613, and 0.9442, respectively. Comparison of the results of natural and synthetic wastes showed that matching with the model and recovery of target elements were more prominent in experiments with synthetic waste (unicomponent) rather than natural waste (multicomponent).
اظهر المزيد [+] اقل [-]Effects of Residual Mulch Film on the Growth and Fruit Quality of Tomato (Lycopersicon esculentum Mill.)
2017
The quantities of residual mulch film in the soil will further increase with the wide application of agricultural plastic mulch film, and the pollution of residual mulch film, which is a continuous pollutant and the one that is difficult to degrade, is a major limiting factor for the sustainable development of agriculture in China. Residual mulch film in the soil inevitably affects soil hydrodynamic parameters, destroys the homogeneity of the soil texture, seriously impedes the movement of soil water and solutes, and thus greatly influences crop growth and fruit quality. To unravel the effects of residual mulch film on tomato growth and fruit quality, pot experiments in the greenhouse were carried out in 2015 and 2016 in Northwest China. Six levels of residual mulch film were applied: 0 kg ha⁻¹ (CK), 80 kg ha⁻¹ (T1), 160 kg ha⁻¹ (T2), 320 kg ha⁻¹ (T3), 640 kg ha⁻¹ (T4), and 1280 kg ha⁻¹ (T5). Plant height, stem diameter, dry biomass, yield, root length, root surface area, fruit shape index (FSI), soluble sugar content (SSC), organic acid (OA), vitamin C (VC), lycopene, and nitrate content (NC) were measured. Plant height, stem diameter, dry biomass, and yield of tomato had a downward trend as the residual mulch film amount increased. Root length and root surface area were significantly decreased with an increasing amount of residual mulch film, but root volume and root diameter showed an inconspicuous decrease. When the amount of residual mulch film was more than 80 kg ha⁻¹, growth indexes, dry biomass, and yield of tomato showed a sharp decline. FSI, OA, and lycopene decreased as the residual mulch film amount increased, whereas SSC, VC, and NC showed an increase trend. With the increase in residual mulch film amount, the F and membership function values (X μ) all showed a declining trend in comparison to the CK. Therefore, residual mulch film can aggravate the negative effects on the comprehensive fruit quality of tomato.
اظهر المزيد [+] اقل [-]Association of IL-6 with PM2.5 Components: Importance of Characterizing Filter-Based PM2.5 Following Extraction
2017
Roper, Courtney | Chubb, Lauren G. | Cambal, Leah | Tunno, Brett | Clougherty, Jane E. | Fattman, Cheryl | Mischler, Steven E.
Filter-based toxicology studies are conducted to establish the biological plausibility of the well-established health impacts associated with fine particulate matter (PM₂.₅) exposure. Ambient PM₂.₅ collected on filters is extracted into solution for toxicology applications, but frequently, characterization is nonexistent or only performed on filter-based PM₂.₅, without consideration of compositional differences that occur during the extraction processes. To date, the impact of making associations to measured components in ambient instead of extracted PM₂.₅ has not been investigated. Filter-based PM₂.₅ was collected at locations (n = 5) and detailed characterization of both ambient and extracted PM₂.₅ was performed. Alveolar macrophages (AMJ2-C11) were exposed (3, 24, and 48 h) to PM₂.₅ and the pro-inflammatory cytokine interleukin (IL)-6 was measured. IL-6 release differed significantly between PM₂.₅ collected from different locations; surprisingly, IL-6 release was highest following treatment with PM₂.₅ from the lowest ambient concentration location. IL-6 was negatively correlated with the sum of ambient metals analyzed, as well as with concentrations of specific constituents which have been previously associated with respiratory health effects. However, positive correlations of IL-6 with extracted concentrations indicated that the negative associations between IL-6 and ambient concentrations do not accurately represent the relationship between inflammation and PM₂.₅ exposure. Additionally, seven organic compounds had significant associations with IL-6 release when considering ambient concentrations, but they were not detected in the extracted solution. Basing inflammatory associations on ambient concentrations that are not necessarily representative of in vitro exposures creates misleading results; this study highlights the importance of characterizing extraction solutions to conduct accurate health impact research.
اظهر المزيد [+] اقل [-]Removal of Amoxicillin in Aqueous Solution by a Novel Chicken Feather Carbon: Kinetic and Equilibrium Studies
2017
Li, Huiqin | Hu, Jingtao | Wang, Chuan | Wang, Xiaojing
Chicken feather, which is consisted of keratin, has always been abandoned as solid waste. The utilization technologies of waste keratin have been developed in electric zones and materials fields so far. Recently, numerous new types of adsorbents have been used for antibiotic removal. The chicken feather carbon is supposed to be a potential one. In this study, an activated feather carbon (AFC) was developed as the absorbent of amoxicillin (AMOX) in simulated wastewater. The micropore structures of AFC were detected by the scanning electron microscope (SEM). X-ray photoelectron spectrum (XPS) was recorded and analyzed. A BET surface area, as high as 1838.86 m²/g, was measured in this study. At the meantime, a rapid adsorption (5∼7 min) and high removal efficiency (99.63%) could be observed. The kinetics, isotherms, and thermodynamic studies indicated that the adsorption of AMOX by AFC was an exothermic physic-adsorption. The interaction between AMOX and AFC surface was supposed to be a multiple-layer adsorption process for it is well fitted with the Freundlich model. The adsorption behavior could be described by pseudo-second-order model almost perfectly in kinetic studies. In addition, effect of pH, ionic strength, and reusability properties were also discussed in this paper. The AFC was proved to be the most rapid, efficient, and economically absorbent for AMOX removal, which was effective enough under various temperatures and saline circumstances. It was also proved useful, convenient, and renewable in dealing with the tough antibiotic pollutant problems and rebuilding of antibiotic sewage treatment facilities.
اظهر المزيد [+] اقل [-]Rhizobacterial Pseudomonas spp. Strains Harbouring acdS Gene Could Enhance Metallicolous Legume Nodulation in Zn/Pb/Cd Mine Tailings
2017
Soussou, Souhir | Brunel, Brigitte | Pervent, Marjorie | van Tuinen, Diederik | Cleyet-Marel, Jean-Claude | Baudoin, Ezékiel
Phytostabilisation can benefit from phytostimulatory rhizobacteria. Forty-three bacterial strains were isolated from the roots of the metallicolous legume Anthyllis vulneraria ssp. carpatica grown in a highly contaminated mine tailing (total Cd, Pb and Zn were up to 1200; 34,000; and 170,000 mg kg⁻¹, respectively). We aimed at evaluating their phytostimulatory effects on the development of leguminous metallophytes. Strains were screened for fluorescent siderophores and auxin synthesis, inorganic P solubilisation and 1-amino-cyclopropane-1-carboxylate deaminase (ACCd) activity to define a subset of 11 strains that were inoculated on the leguminous metallophytes A. vulneraria and Lotus corniculatus grown in diluted mine spoil (Zn 34,653; Pb 6842; and Cd 242, all in mg kg⁻¹). All strains were affiliated to Pseudomonas spp. (except two), synthetised auxins and siderophores and solubilised P (except three), and seven of them were ACCd positive. The inoculation effects (shoot-root-nodule biomass, chlorophyll content) depended on legume species and bacterial strain genotype. Phytostimulation scores were unrelated to siderophore/auxin synthesis and P solubilisation rates. Inoculations of the strain nos. 17–43 triggered a 1.2-fold significant increase in the chlorophyll content of A. vulneraria. Chlorophyll content and root biomass of L. corniculatus were significantly increased following the inoculations of the strain nos. 17–22 (1.5–1.4-fold, respectively). The strongest positive effects were related to increases in the nodule biomass of L. corniculatus in the presence of three ACCd-positive strains (1.8-fold), one of which was the highest auxin producer. These data suggest to focus on interactions between ACCd activity and auxin synthesis to enhance nodulation of metallicolous legumes.
اظهر المزيد [+] اقل [-]Actual Situation of Asbestos in Tract Drinking-Water in Korean and Japanese Local Cities
2017
Ma, Chang-Jin | Kang, Gong-Unn
Although every year, thousands of people die from asbestos-related diseases, many people disregard things that are past. Meanwhile, a lot of people, in particular, in many Asia countries that have no guideline values for waterborne asbestos are currently in a fever of anxiety about the possibility of its health hazards. This study focused on a grasping the actual situation of asbestos in household tap water. An intensive collection of the tract drinking-water was conducted in Iksan, Korea (at six homes), and Fukuoka, Japan (at nine homes). After pretreatment, both morphological observation and elemental analysis were simultaneously carried out using a scanning electron microscopy (SEM) with an energy dispersive X-ray spectrometer (EDX). The concentrations of waterborne asbestos fiber varied from place to place in both local cities. Their average concentrations at all sites in Iksan and Fukuoka were 213.3 and 181.1 f/L, respectively. Although the measured values in this study were the sum of chrysotile, amosite, and crocidolite fibers with a high risk of cancer, they were found to be consistently below the MCL (the Maximum Contaminant Level recommended by the U.S. toxicological profile for Asbestos). A significant link was found between open water supply channels and waterborne asbestos. The backward wind trajectory projections indicated that the present water sampling sites might be affected by the airborne asbestos fiber in the upwind atmosphere.
اظهر المزيد [+] اقل [-]Reaction Mechanism and Degradation Pathway of Rhodamine 6G by Photocatalytic Treatment
2017
Rasheed, Tahir | Vēlāyutan̲, T. A. | Iqbal, Hafiz M. N. | Hu, Hongbo | Zhang, Xuehong
The photocatalytic degradation of a cationic dye, rhodamine 6G (Rh-6G) under UV light irradiation was carried out. Rh-6G was completely decolorized in 180 min of photo-oxidative degradation period. The extent of degradation was confirmed performing total organic carbon (TOC) analysis, and up to 90.14%, TOC removal was achieved. Several critical analytical techniques including UV-Vis spectroscopy, high-performance liquid chromatography (HPLC), and ultra-performance liquid chromatography coupled with electrospray ionization mass spectrometry (UPLC/MS) were employed to scrutinize the mechanistic insights of the dye photodegradation. The degraded N-demethylation intermediates and several small molecular products were qualitatively identified, and a tentative photodegradation pathway was proposed. Toxicological evaluation of the degradation products was carried out three types of cell lines (MTT assay) and Triticum sativum seeds. In conclusion, enhanced biodegradability accompanied by toxicity reduction confirmed the promising efficiency of photocatalysis for Rh-6G degradation and therefore could be used for the remediation of textile effluents.
اظهر المزيد [+] اقل [-]Simultaneous Detection of 13 Endocrine Disrupting Chemicals in Water by a Combination of SPE-BSTFA Derivatization and GC-MS in Transboundary Rivers (France-Belgium)
2017
Sghaier, RafikaBen | Net, Sopheak | Ghorbel-Abid, Ibtissem | Bessadok, Salma | Le Coz, Maïwen | Hassan-Chehimi, DalilaBen | Trabelsi-Ayadi, Malika | Tackx, Michele | Ouddane, Baghdad
The occurrence of endocrine-disrupting chemicals (EDCs) in the aquatic environment has brought increasing concern due to their potential adverse impacts on ecosystems and humans. These compounds are generally present in complex water matrices, such as surface waters at trace levels (ng L⁻¹) making their analysis difficult. In this work, an analytical method for the simultaneous determination of 13 EDCs, including 5 steroid estrogens, 1 progestogen, 1 androgen, and 6 endocrine-disrupting phenols in water, was developed using solid phase extraction (SPE), derivatization, and gas chromatography-mass spectrometry (GC-MS). The method was validated by spiking the 13 EDCs to the interest matrix. The recovery was in the range of 52–71% with an average of 62%. The limits of quantification were 1 and 5–10 ng L⁻¹ for phenolic compounds and hormones, respectively. The validated method was applied to assess the contamination level of the targeted EDCs in 15 sites collected from six rivers located at the cross-border area of Northern France and Belgium. The majority of the considered compounds were detected in the sampling sites and among them, bisphenol A (BPA) was found at the highest level which can be up to 286 ng L⁻¹. However, NP was the most frequently detected, followed by BPA and PG.
اظهر المزيد [+] اقل [-]The Contribution of Pyrene Degrading Bacteria and Chemical Reagents to Scirpus triqueter Phytoremediation of Pyrene and Ni Co-contaminated Soil
2017
Hu, Xiaoxin | Zhang, Xinying | Liu, Xiaoyan | Cao, Liya | Chen, Jing | Huo, Zhuhao
Phytoremediation of organic pollutant and heavy metal (HM) co-contaminated soils shows many advantages and can be improved by adding chemical reagents or inoculating with degrading bacteria. In this study, pot culture experiments were performed to explore the effects of chemical reagents (nitrilotriacetic acid and alkyl polyglucoside), pyrene degrading bacteria HD-1, and their combination on phytoremediation efficiency for pyrene and nickel (Ni) co-contaminated soil by Scirpus triqueter. After a 60-day culture, plant biomass, pyrene dissipation from soil, Ni accumulation in plant, and Ni accessibility in co-contaminated soil were determined. Results showed that although the application of chemical reagents alone had no apparent effect on plant growth, their combination with the introduced HD-1 alleviated the inhibition effects on plant growth in co-contaminated soil. The dissipation of pyrene in the soil with plant (P), soil with bacteria (NPB), soil with chemical reagents (NPC) and soil with both of them (PBC) were 35.49, 51.36, 42.89, and 59.78%, respectively, and were higher than NP (19.52%) with neither of them. The Ni concentration in Scirpus triqueter of group with bacteria (PB), group with chemical reagents (PC) and group PBC increased to 100.40, 80.97 and 87.77 mg kg⁻¹ respectively when compared with that of group P (46.04 mg kg⁻¹) without bacteria or chemical reagents. Besides, inoculation with HD-1 or/and adding chemical reagents caused Ni to shift from less bioavailable forms to more bioavailable forms. This study suggested the contribution of pyrene degrading bacteria and chemical reagents to Scirpus triqueter phytoremediation of pyrene and Ni co-contaminated soil.
اظهر المزيد [+] اقل [-]Toxic Assessment of Cadmium Based on Online Swimming Behavior and the Continuous AChE Activity in the Gill of Zebrafish (Danio rerio)
2017
Pan, Hongwei | Zhang, Xu | Ren, Baixiang | Yang, Huanhuan | Ren, Zongming | Wang, Weiliang
The cadmium (Cd) contamination in the aquatic environment has attracted more and more attention due to its toxicity characteristics, e.g., accumulation in the environment, non-degradability, and the potential threat to the ecosystem. In this research, in order to illustrate the potential threat of heavy metal Cd to aquatic organisms, the online swimming behavior and the continuous acetylcholinesterase (AChE) activity in the gill of Zebrafish (Danio rerio) in 48 h exposure of cadmium chloride (CdCl₂) (4.26 mg/L (0.1 TU, toxic unit), 42.6 mg/L (1.0 TU), and 85.2 mg/L (2.0 TU)) are investigated. The behavior responses of D. rerio based on behavior strength (BS) have obvious dose-effect relationship, and lower BS values could be observed in the dark period at 13–21 h and 37–45 h in all treatments. The circadian rhythm could be observed even in all treatments (0.1, 1.0, and 2.0 TU), and the rhythm was disrupted with 1.0 TU at the end of the experiment whereas the lower (0.1 TU) and higher (2.0 TU) levels showed clear rhythms. These results suggested that the online BS values could illustrate the toxicity of CdCl₂ directly. The AChE activity in the gill is strongly inhibited by CdCl₂ based on the continuous sample results during 48 h exposure. The cross-correlation results using DCCA show a high correlation (r > 0.5) with extreme significance (p < 0.01), which suggest that the exposure in CdCl₂ can affect the AChE activity of D. rerio, and then damage the transduction signal due to neurotoxicity, which may induce decrease of swimming behavior, loss of coordination, and other kinds of behavior changes.
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