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21.
Smith PA Alexander WR Kickmaier W Ota K Frieg B McKinley IG 《Journal of contaminant hydrology》2001,47(2-4):335-348
The joint Swiss National Co-operative for the Disposal of Radioactive Waste (Nagra)/Japan Nuclear Cycle Development Institute (JNC) Radionuclide Migration Programme has now been on-going for over a decade in Nagra's Grimsel Test Site (GTS). The main aim of the programme has been the direct testing of radionuclide transport models in as realistic manner as possible. Although it will never be possible to fully test these models due to the large time and distance scales involved, tests of the model assumptions in scaled down but otherwise realistic conditions will contribute to developing confidence in the predictive power of the models. In this paper, the Nagra/JNC approach is highlighted with examples from a large programme of field, laboratory and natural analogue studies based around the GTS. The successes and failures are discussed as in the general approach to the thorough testing of predictive transport codes which will be used in repository performance assessment (PA). Some of the work is still on-going and this represents the first presentation of a unique set of results and conclusions. 相似文献
22.
Measuring heavy metal migration rates in a low-permeability soil 总被引:2,自引:0,他引:2
Heavy metals at high concentrations are often toxic to living organisms, and their environmental toxicity depends on soil
properties. It has long been thought that in clay-rich, low-permeability soils, heavy metals are bound to soil particles,
and thus there are only few toxicity risks. This study questioned this perception and tested heavy metal mobility in such
a soil, of the London Clay series, using a benchtop centrifuge. Soil columns were placed in the centrifuge and were infiltrated
with solutions of Cu, Ni and Zn ions, while the centrifuge was running at three different gravity levels, at 5,280, 2,600
and 1,300 gravities. The measured rates of migration of Cu, Ni and Zn ions were extrapolated down to 1 gravity, which represents
field conditions, the conditions for which an assessment of risk due to metal toxicity would be needed. It was found that
heavy metal movement was significant in London Clay, Ni being the most mobile metal in the study, followed by Zn and then
Cu ions. Centrifuge infiltration tests were proven to be a valuable tool in the study and quantification of metal mobility
in low-permeability soil, because they were easy to run and precise in predicting metal movement in London Clay.
Electronic Publication 相似文献
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24.
Paul H. Whitfield James W. McKinley 《Journal of the American Water Resources Association》1981,17(3):381-386
The effect of storing samples prior to determination of particulate nitrogen and carbon concentrations were investigated. Freezing of water samples between collection and analysis has a substantial effect on the results obtained. Storage of samples at 5°C also affects the results, although the changes which occurred were generally less than for frozen samples. When the particulates were collected onto a filter immediately after sample collection and stored in that form until analysis only small changes in the results were observed. This suggests that samples for the determination of particulate nitrogen and carbon concentrations should be filtered immediately upon sample collection and the analysis performed as soon as possible. 相似文献