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471.
H. von Schelling 《Die Naturwissenschaften》1942,30(20-21):306-312
472.
Edmund O. von Lippmann Arn Berliner E. Th. Brücke E. Berl 《Die Naturwissenschaften》1930,18(13):283-285
473.
Slag arising in ferrochromium and stainless steel production is known to contain residual levels of trivalent chromium. As the chromium is normally bound in the slag matrix in various silicate or spinel phases, and hence not easily mobilised, utilisation or controlled disposal of such slag is generally considered unproblematic. Experimental test work with a number of slag materials indicates, however, that very gradual oxidation of trivalent to hexavalent chromium does occur when the slag is exposed to atmospheric oxygen, rendering a quantifiable but small portion of chromium in this much more mobile and toxic form. Mechanisms and rates of the oxidation reaction were investigated in a number of long-term studies using both original slag materials and artificial mixes of chromium and calcium oxides. Powders of these materials, some of them rolled into balls, were left to age under different conditions for periods of up to 12 months. In the slag samples, which contained between 1 and 3 wt.% chromium, 1000–10 000 μg Cr(VI) were found per gram of chromium within 6–9 months of exposure to an ambient atmosphere. The rate of the oxidation reaction decreased exponentially, and the reaction could generally be said to have ceased within 12 months. In mixtures of calcium and chromium oxides the oxidation reaction is presumed to occur at the boundaries between chromium oxide and calcium oxide phases through diffusion of oxygen along the grain boundaries and of Cr3+ across the boundaries, resulting in the formation of calcium chromate. In the slags, where calcium and chromium oxide can form a solid solution, the oxidation is likely to occur at the exposed surface of grains containing this solution. 相似文献
474.
Uwe Heiser Stefan Norra Doris Stüben Magnus von Wagner 《Environmental Sciences Europe》1999,11(1):15-19
For the application of sequential extraction of heavy metals from samples that can only be obtained in amounts of a few milligrams (micro samples, e.g. airborne dust fallout), the method afterZeien &Brümmer (1989) was progressed. A down scale to 1∶100 was carried out and the accuracy of this method with variable sample amounts of about 20 mg and an extraction volume of 500 μl was proofed with standard soil samples. The influence of variable extraction ratios (ratio of sample amount and volume of extraction solvent) and the influence of intensive treatment of dust sampled by the Bergerhoff-method (VDI 2119/2, 1972) prior sequential extraction, was within the precision of measurement of our method. Thus, we showed that sequential extraction can be applied for the investigation of heavy metal mobilization in micro samples with variable sample amounts. A first application of our method for microsamples was carried out to investigate airborne dust fallout and street sediments at two urban sites where different heavy metal immission rates due to traffic influence occur. These investigations will be presented in part 2 (“Sequential extraction of heavy metals from urban dust”). 相似文献
475.
Aalto P Hämeri K Paatero P Kulmala M Bellander T Berglind N Bouso L Castaño-Vinyals G Sunyer J Cattani G Marconi A Cyrys J von Klot S Peters A Zetzsche K Lanki T Pekkanen J Nyberg F Sjövall B Forastiere F 《Journal of the Air & Waste Management Association (1995)》2005,55(8):1064-1076
In this study, long-term aerosol particle total number concentration measurements in five metropolitan areas across Europe are presented. The measurements have been carried out in Augsburg, Barcelona, Helsinki, Rome, and Stockholm using the same instrument, a condensation particle counter (TSI model 3022). The results show that in all of the studied cities, the winter concentrations are higher than the summer concentrations. In Helsinki and in Stockholm, winter concentrations are higher by a factor of two and in Augsburg almost by a factor of three compared with summer months. The winter maximum of the monthly average concentrations in these cities is between 10,000 cm(-3) and 20,000 cm(-3), whereas the summer min is approximately 5000-6000 cm(-3). In Rome and in Barcelona, the winters are more polluted compared with summers by as much as a factor of 4-10. The winter maximum in both Rome and Barcelona is close to 100,000 cm(-3), whereas the summer minimum is > 10,000 cm(-3). During the weekdays the maximum of the hourly average concentrations in all of the cities is detected during the morning hours between 7 and 10 a.m. The evening maxima were present in Barcelona, Rome, and Augsburg, but these were not as pronounced as the morning ones. The daily maxima in Helsinki and Stockholm are close or even lower than the daily minima in the more polluted cities. The concentrations between these two groups of cities are different with a factor of about five during the whole day. The study pointed out the influence of the selection of the measurement site and the configuration of the sampling line on the observed concentrations. 相似文献
476.
477.
478.
479.
G. H. R. von Koenigswald 《Die Naturwissenschaften》1953,40(4):128-137
480.
In Australia, local communities often enact Community-Based Initiatives (CBIs) to respond to climate change through Climate Change Adaptation (CCA). CBIs can also be integrated into the Disaster Risk Reduction (DRR) agenda. The paper explores the extent to which CBIs promote the mainstreaming of CCA into DRR. Primary data were obtained from interviews with representatives of CBIs and supporting organisations in three local governments of the Hunter Valley (New South Wales, Australia). Findings show that CBIs recognise the potential contribution of climate change in modifying the local hazard profile. CBIs mainstream CCA into DRR by following four approaches: environmental and social justice; sustainability and transition; ecosystem-based approach; and adaptive planning. Partnerships were identified both among CBIs and between CBIs and City Councils; however, conflicts between CBIs, City Councils and business actors emerged, and a lack of commitment by multi-level governments in responding to climate change was revealed. The findings show that CBIs consider CCA and DRR within a broad everyday context related to vulnerability and local development. But we argue that assigning responsibility for climate change issues to CBIs is not a panacea and should not be the only local climate change response. Instead, CBIs need to be included in a larger and long-term commitment by actors that possess access to resources, such as higher levels of government. The paper provides a local Australian perspective on the effectiveness of mainstreaming CCA into DRR and furthers the conversation for the benefit of other communities facing similar challenges. 相似文献