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51.
52.
Katja Riedel Rolf Weller Otto Schrems Gert Knig-Langlo 《Atmospheric environment (Oxford, England : 1994)》2000,34(29-30)
The annual cycles of hydrogen peroxide (H2O2) and methylhydroperoxide (MHP) have been investigated at a remote site in Antarctica in order to study seasonal variations as well as chemical processes in the troposphere. The measurements have been performed from March 1997 to January 1998 and in February 1999 at the German Antarctic research station Neumayer which is located at 70°39′S, 8°15′W. The obtained time series for hydrogen peroxide and methylhydroperoxide in near-surface air represents the first all-year measurements in Antarctica and indicates clearly the occurrence of seasonal variations. During polar night mean values of 0.054±0.046 ppbv (range<0.03–0.11 ppbv) for hydrogen peroxide and 0.089±0.052 ppbv (range<0.05–0.14 ppbv) for methylhydroperoxide were detected. At the sunlit period higher Mixing ratios were found, 0.20±0.13 ppbv (range<0.03–0.91 ppbv) for hydrogen peroxide and 0.19±0.10 ppbv (range<0.05–0.89 ppbv) for methylhydroperoxide. Occasional long-range transport of air masses from mid-latitudes caused enhanced peroxide concentrations at polar night. During the period of stratospheric ozone depletion we observed peroxide mixing ratios comparable to typical winter levels. 相似文献
53.
Effect of methylmercury on LPO levels, SH groups and activities of GSH-Px, SOD, XOD in liver of rats 总被引:1,自引:0,他引:1
LIU Jin |yu GUAN Ming SUN Zhi |wei LIN Xiu |wu CAO Peng |yuan MENG Xiang |dong 《环境科学学报(英文版)》2000,(Z1)
iththeintroductionofagriculturalandindustrialdevelopmentandimprovementofhumanlife ,environmentalpollutionbecomesmoreandmoreofconcernforpeople.MeHgisoneoforganiclipidsoluble ,heavymetallicpollutants.Althoughitsbiologicaleffectswerestudiedinmanyfieldsbyre… 相似文献
54.
Fabio Orecchini 《Sustainability Science》2007,2(2):245-252
Human society consumes resources that it is not able to reproduce. Human activities are still based on “open cycles,” starting
from a condition of natural environmental balance and reaching an environmental imbalance. The challenging scope of scientific
and technological research towards sustainability appears clear if it is based on this analysis: to find development systems
based on “closed cycles” of resources. The challenging objective of realizing closed cycles leads to a definition of sustainability
that indicates the path to sustainable development, as well as stating the general principle. It also provides a key to the
qualitative measurement of sustainability. This means that the sustainability level of a system can be measured by measuring
its capacity to avoid the consumption of resources. Zero consumption is a necessary condition for sustainability, and brings
about as a side effect the highly desired “zero-waste” result. Materials entering the proposed endless scheme pass through
the process of usefulness without losing their capacity to feed the system again after being used. Thus, the concept of “consumption”
itself is replaced by one of “use” when resources are inserted into closed loops capable of feeding human development. The
application of the closed cycle sustainability criterion particularly displays its feasibility, and a theoretical guiding
role, in the energy sector. Energy vectors such as hydrogen and electricity enable the closure of the energy resources loop
by effectively approaching the objective of “zero consumption” (and the side result of “zero waste”) through already demonstrated
technological solutions. 相似文献
55.
In many countries where electricity generation is based on their natural resources of fossil fuels a need arises to implement new power engineering technologies that allow carbon dioxide capture. Simultaneously, efforts are made to find new energy carriers which, if fired, do not involve carbon dioxide emissions. Hydrogen is one of such fuels with this future potential which is now becoming increasingly popular. Obviously, this means that the two gases mentioned above – carbon dioxide and hydrogen – will be produced in large quantities in future, which in many cases will necessitate their transport over considerable distances. If a pipeline failure occurs, the transport of the gases may pose a serious hazard to people in the immediate vicinity of the leakage site. This paper presents an analysis of the possibility of reducing the level of risk related to pipelines transporting CO2 and H2 by means of safety valves. It is shown that for a 50 km long and a 0.4 m diameter pipeline transporting gas with the pressure of 15 MPa the individual risk level can be reduced from 1·10−4 to 6.5·10−7 for CO2 and from 1·10−6 to 6·10−10 for H2. The social risk can be diminished in similar proportions. 相似文献
56.
有机过氧化物的易燃、受热分解等特殊性质和生产、储运过程要求严格的低温条件与操作程序,使得有机过氧化物潜在的危险性很高。通过基于有机过氧化物危险特性及其在生产、储运过程中物质、能量与信息的分析,依据物-能量-信息的安全要素体系,应用危险与可操作分析方法,研究了有机过氧化物的安全理论,在某种程度上是延伸了HAZOP分析的内容。 相似文献
57.
There is a clear difference between exiting data on the measured flammability limits of hydrogen-air mixture. The non-uniformity of concentration distribution of hydrogen in air is a contributor to deviations of the upper flammability limit (UFL) and the lower flammability limit (LFL) measured in different experiments. This paper presents a numerical model to simulate the gas mixing process from start to stability, to predict the concentration distribution, and to research the influence of concentration distribution of hydrogen in air on measured UFLs and LFLs. The commercial software package Fluent was used to carry out the numerical simulation for the concentration distribution of hydrogen in air in the vessels with length-to-diameter ratios (L: D) of 1:1, 3:1, 5:1 and 7:1 respectively. Based on the numerical simulation and analysis, the influence of concentration distribution on measured flammability limits was demonstrated for hydrogen in air in the vessel. It is found that the deviations of measured flammability limits of hydrogen in air are the minimum in the vessel with length-to-diameter ratio of 1:1, and augment with the augmentation of vessel length-to-diameter ratio. Moreover, it is presented that the deviations of measured flammability limits of hydrogen in the center of the vessel are lower than that in the top and the bottom. 相似文献
58.
过氧化氢对铜绿微囊藻的损伤效应研究 总被引:2,自引:2,他引:0
采用室内培养的方法研究了不同浓度H2O2对铜绿微囊藻(Microcystic aeruginosa)藻细胞的损伤效应.结果表明,H2O2浓度越大,对藻细胞的毒害作用越大.24 h之后,铜绿微囊藻藻细胞数、叶绿素a、类胡萝卜素和蛋白质含量及总抗氧化能力(T-AOC)都快速下降,而MDA含量显著增加,同时培养基中的H2O2含量也迅速降低;随着处理时间的增加,毒性效应逐渐增强;72 h之后,藻细胞各指标值都降得很低,MDA含量也增加到最大,培养基中H2O2也逐渐被消耗和分解,藻细胞的损伤效应也达到最大.其中,H2O2浓度为50 mg·L-1时,能够有效的去除藻细胞,并且对藻细胞的生理指标及抗氧化能力都有很强的损伤效应. 相似文献
59.
As one of the transition metals, vanadium (V) (V(V)) in trace amounts represents an essential element for normal cell growth, but becomes toxic when its concentration is above 1 mg/L. V(V) can alter cellular differentiation, gene expression, and other biochemical and metabolic phenomena. A feasible method to detoxify V(V) is to reduce it to V(IV), which precipitates and can be readily removed from the water. The bioreduction of V(V) in a contaminated groundwater was investigated using autohydrogentrophic bacteria and hydrogen gas as the electron donor. Compared with the previous organic donors, H2 shows the advantages as an ideal electron donor, including nontoxicity and less production of excess biomass. V(V) was 95.5% removed by biochemical reduction when autohydrogentrophic bacteria and hydrogen were both present, and the reduced V(IV) precipitated, leading to total-V removal. Reduction kinetics could be described by a first-order model and were sensitive to pH and temperature, with the optimum ranges of pH 7.5–8.0 and 35–40°C, respectively. Phylogenetic analysis by clone library showed that the dominant species in the experiments with V(V) bioreduction belonged to the β-Proteobacteria. Previously known V(V)-reducing species were absent, suggesting that V(V) reduction was carried out by novel species. Their selective enrichment during V(V) bioreduction suggests that Rhodocyclus, a denitrifying bacterium, and Clostridium, a fermenter known to carry out metal reduction, were responsible for V(V) bioreduction. 相似文献
60.
The coupled fluid-structure-rupture model was developed to study the propagation and intensity of blast wave from hydrogen pipe rupture due to internal detonation. The dynamic rupture of pipe and propagation of blast wave were well coupled together in every timestep during the simulation. The numerical model was validated with experiments in terms of both typical rupture profiles and blast overpressures. Results reveal that crack branching of pipe can dramatically increase the rupture opening rate which controls the intensity and shape of the resultant blast wave. Due to the process of crack initiation and extension, the blast wave out of the pipe first forms and then is strengthened by the subsequent compression waves. This makes the maximum peak overpressure appears at a certain standoff distance above the rupture. Despite consuming some percentages of energy, the dynamic rupture of pipe generally presents positive effects (up to 2–3 times) on the blast wave intensity along the jetting direction due to the convergence effect of rupture opening on the release of internal high-pressure gas. Finally, through defining normalized overpressure and impulse based on the same hydrogen detonation in open spaces, the quantitative influences of pipe rupture on the blast wave intensity in cases of different detonation pressures and standoff distances are clarified. 相似文献