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531.
考察了不同有机改性硅对微囊藻毒素LR(mLR)和LA(mLA)的等温吸附行为。结果表明,有机改性硅可有效吸附去除水体中<0.1×10-6(质量分数)的微囊藻毒素,并且吸附去除效果随表面改性官能团中碳原子数量的增加而增加;相同条件下,有机改性硅在微囊藻毒素异构体之间存在着一定的吸附选择性。 相似文献
532.
Sorption of metals onto natural organic matter as a function of complexation and adsorbent-adsorbate contact mode 总被引:1,自引:0,他引:1
The effect of complexing anion and adsorbate-adsorbent contact mode (static equilibrium or dynamic non-equilibrium) on binding and partition of Cu(2+), Cd(2+) and Zn(2+) onto organic matter (exemplified in a low-moor peat) was studied. The study comprised comparative batch and column flow-through sorption experiments on monometallic solutions of Me-Cl and Me-SO(4) salts, at pH 4.0, and sequential fractionation of sorbed metals with respect to binding strength. Both the presence of an anion having complexing properties (Cl(-)) as well as a contact mode was found to quantitatively and qualitatively affect the sorption capacity and binding strength of organic matter (peat) for metal ions. Complexing effect of Cl(-) on metal ions resulted mostly in reduction of metal ability to form strongly bound metal-organic compounds, in accordance with the order of stability constant of complex ions log K: Cd>Zn>Cu. Flow-through (dynamic) contact mode, which is the most appropriate to simulate environmental conditions, appeared to strongly attenuate the complexing effect of chloride ions on Cd and Zn sorption, and significantly enhance sorption capacity also in the absence of complexing ions. For Cd, it was mainly due to the enrichment in the strongly bound "insoluble organic" fraction, while for Zn the quantitative increase of sorption capacity did not alter significantly its partitioning. Neither a quantitative nor qualitative effect of contact mode on Cu binding was observed. Complex and diverse effects of different environmental parameters on metal sorption capacity and binding strength onto organic matter, which strongly influence metal mobility, leads to the conclusion that the correct simulation of these parameters for ecotoxicological testing is crucial for the reliable predicting of metal bioavailability under actual terrestrial environmental conditions. 相似文献
533.
Lindahl P Maquet A Hult M Gasparro J Marissens G González de Orduña R 《Journal of environmental radioactivity》2011,102(2):163-169
The distribution of natural radionuclides was studied in winter wheat plants collected from three sites in Belgium during 2004-2007. Activity concentrations of 40K, 226Ra, 228Ra and 228Th in organically and conventionally grown wheat, and in the corresponding soil samples, were determined using ultra low-level gamma-ray spectrometry. The observed soil-to-wheat concentration ratios were calculated for the different parts of the wheat plant (root, stem and grain) in the two agricultural systems (organic and conventional). There were large variations in radionuclide activity concentrations between the sites and fields, but no significant difference between conventionally and organically grown wheat plants was observed. 相似文献
534.
Andrew Turner Geoffrey E. Millward Martin Stemp 《Journal of environmental radioactivity》2009,100(10):890-895
Tritium is an important environmental radionuclide whose reactivity with ligands and solids in aquatic systems is assumed to be limited. We studied the fractionation and sorption of tritium (added as tritiated water) in river water and seawater, and found that its distribution appears to be influenced by its affinity for organic matter. Tritium rapidly equilibrates with dissolved organic ligands that are retained by a reverse-phase C18 column, and with suspended sediment particles. Significantly, a measurable fraction of sorbed tritium associates with proteinaceous material that is potentially available to sediment-feeding organisms. These characteristics have not been reported previously and cannot be accounted for solely by isotopic exchange with hydrogen. Nevertheless, they are in qualitative agreement with available measurements of tritium in estuarine and coastal waters where its principal discharge is as tritiated water. Further research into the estuarine biogeochemical behaviour of tritium is required and radiological distribution coefficients and concentration factors that are assumed for this radionuclide may require reconsideration. 相似文献
535.
简述了近年来高效液相色谱-电感耦合等离子体质谱联用技术(HPLC-ICP/MS)在环境有机汞分析中的应用进展,介绍了水、土壤和沉积物及生物样品的前处理方法,对仪器设备的要求和分析条件,以及线性范围、检出限、精密度与准确度等方法性能参数,并对现有文献方法的适用性进行了总结。 相似文献
536.
537.
Organic hydride hydrogen refueling stations have been remarked as stations that can employ a practicable method based on the organic chemical hydride system involving methylcyclohexane (MCH) for the transport of hydrogen. This station has advantages in that the storage and transportation of MCH does not require a large amount of energy compared to compressed and liquefied hydrogen, and the system can use existing infrastructure. This type of station involves some hazardous materials, and thus, scenario identifications and risk assessments have been performed by researchers. However, the sample of studies available have employed a conceptual design model, and they did not identify concrete scenarios triggered by internal factors. Therefore, the purpose of this study is to identify accidental scenarios caused by internal factors that can affect an organic hydride hydrogen refueling station. In this study, we used Hazard and Operability study (HAZOP) and examined safety measures for the scenarios. As a result of the HAZOP, 105 accidental scenarios were identified and classified into the two following groups; (i) the scenarios assumed that the substances were ignited after they were released to the atmosphere, and (ii) the scenarios assumed that the substances were ignited in the process before they were released. Significant scenarios in group (i) were MCH or toluene pool fires, hydrogen jet fires, vapor gas explosions, or flash fires. The significant scenarios classified in (ii) were newly identified in this study. The scenarios include the explosion of the explosive mixture formed by the gaseous phase of toluene and oxygen from the vent line connected to the tank due to the static electric charge in the tank. For each scenario, safety measures to prevent the progression of the accident scenario were examined with reference to the current laws and regulations in Japan. 相似文献
538.
K. D. Wehrstedt A. Knorr P. Schuurman 《Journal of Loss Prevention in the Process Industries》2003,16(6):523-531
Tests according to the UN Recommendations on the Transport of Dangerous Goods for the determination of explosive properties of organic peroxides have been compared with screening criteria for explosivity based on measurements in a closed mini-autoclave (MCPVT). It will be shown that an additional screening test may be helpful but the information obtained from the UN tests are more important to characterise the specific properties of a substance under different conditions. 相似文献
539.
540.
Rivaldo A. B. Kpadonou Bruno Barbier Tom Owiyo Fatima Denton Franck Rutabingwa 《Natural resources forum》2019,43(1):41-55
Using a stepwise approach that combines several econometric methods, we assessed whether or not the adoption of modern seeds and the use of manure in cereal‐based systems are linked and, if so, what are the driving forces of the linkages between these two agricultural technologies under dry‐climate conditions in West Africa. We found complementary and substitutability linkages arising from jointness and endogeneity between the two technologies. Specifically, our findings reveal positive joint determination along with negative endogeneity between the two technologies indicating that, controlling for observable variables, both technologies are positively linked, but unobserved factors that affect one adoption decision are negatively correlated with the other. After controlling for jointness and endogeneity, we found significant complementarity linkages showing a significant positive effect of manure use on the adoption of modern seeds, which is also significantly and positively affected by the number of cash crops grown and remittances. The two technologies are reversely affected by schooling and the incidence of soil fertility problems within the farm, whereas the amount of healthy land has a positive effect on both. The study suggests that organic fertilizer can serve as an enabling factor for greater adoption of modern seeds, especially in less favourable climate areas, and strongly supports the argument behind the need to breed seeds suitable for the use of organic fertilizers. These findings provide avenues for re‐orientation of policies that promote the use of modern seeds in dryland areas in sub‐Saharan Africa, with a possibility of breeding and promoting them in packages with organic fertilizers to upscale their adoption. 相似文献