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61.
Nick D. Bryan Liam Abrahamsen Nick Evans Peter Warwick Gunnar Buckau Liping Weng Willem H. Van Riemsdijk 《Applied Geochemistry》2012
Some recent developments made during the European Union 6th Framework Integrated Project FUNMIG in the understanding and prediction of behaviour in ternary systems of radionuclides, humic substances and mineral surfaces are described. These developments are placed in the context of the existing literature. The aim is to describe the current understanding of humic substance mediated radionuclide transport as it may be applied to calculations in support of Radiological Performance Assessment. Some improvements in experimental techniques that provide the raw data to calibrate metal ion binding models are explained. The various metal ion binding models that are available are described and contrasted, before the recent development of ternary system models, in particular the Ligand Charge Distribution model that can predict metal ion and humic substance behaviour in ternary systems. The kinetic effects in ternary systems are described along with the models that are used to describe them. Finally, the remaining challenges in making predictions of radionuclide transport for the Radiological Performance Assessment of radioactive waste repositories are discussed. 相似文献
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Massimo Tavoni Enrica De Cian Gunnar Luderer Jan Christoph Steckel Henri Waisman 《Climatic change》2012,114(1):39-57
This paper assesses the economic value associated with the development of various low-carbon technologies in the context of climate stabilization. We analyze the impact of restrictions on the development of specific mitigation technologies, comparing three integrated assessment models used in the RECIPE comparison exercise. Our results indicate that the diversification of the carbon mitigation portfolio is an important determinant of the feasibility of climate policy. Foregoing specific low carbon technologies raises the cost of achieving the climate policy, though at different rates. CCS and renewables are shown to have the highest value, given their flexibility and wide coverage. The costs associated with technology failure are shown to be related to the role that each technology plays in the stabilization scenario, but also to the expectations about their technological progress. In particular, the costs of restriction of mature technologies can be partly compensated by more innovation and technological advancement. 相似文献
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The purpose of the present paper is to analyse factors controlling total concentration and aqueous speciation of aluminium in the Große Ohe River, using a thermodynamic equilibrium model and a mixing approach. A model compound for humic substances is derived on the basis of the relation between anion deficit and the organic carbon content in the river as well as literature data. An equilibrium speciation model for aluminium is set up, considering this model compound and relevant inorganic solutes. Although the model cannot be verified directly, its results may be viewed as qualitatively correct. Applying the model to measured stream water samples highlights that aqueous speciation of aluminium is mainly controlled by the pH value and discharge and that free aluminium concentrations reach clearly toxic levels during acidic episodes. Comparing measured concentrations of sulfate and H+ and calculated concentrations of Al3+ with solubility curves of gibbsite like minerals and jurbanite clearly shows that total aluminium concentrations are not controlled by equilibria with these mineral phases alone. The observed relationship can be better explained from a mixture of two distinct waters, representing lowflow and highflow chemistry, and the resulting equilibrium concentrations. This indicates that total aluminium concentration, in particular during high discharge events, is mainly controlled by the mixture of waters with differing chemistry and flowpaths. 相似文献
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Regional co-development and security:: a comprehensive approach 总被引:1,自引:0,他引:1
Concepts of security are no longer limited to the military form, but other potential, economic, ecological, social aspects are becoming included.Emphasis needs to be put on integration of all dimensions of security. Many environmental problems present threats to human health and welfare and hence to the well-being of nations. The environmental issues cannot be ignored in context of any comprehensive security concept, but environmental security should not be treated in isolation.Integration of sustainable development and regional security may address many of the current maritime issues. Such integration may best be handled jointly and at regional levels.With this in mind and the realization that there is now a clear awareness and understanding that issues such as poverty, underdevelopment, population growth, environmental quality and sustainable resource use, are interrelated and interdependent and must be dealt with as such, the paper aims to highlight some aspects of regional security and sustainable development issues with reference to the Mediterranean basin. The aim is to initiate a process to pursue integration of sustainable development and comprehensive regional security with focus on the Mediterranean.The approach is based on the concept of the Common Heritage of Mankind as proposed by Arvid Pardo in 1967. It has 4 dimensions: economic; ethical; environmental; peace and security. In dealing with the proposal of Arvid Pardo the United Nations General Assembly decided to split up the concept: the Conference on the Law of the Sea was to deal with the peaceful uses of oceans and sea-beds; the Conference on Disarmament with the security aspects, then considered as military. UNCED 92 maintained the separation in addressing only environment and development, with management also included. However, peace and security were not included. It is time now to include these elements, and also consider the enforcement issue. The paper aims at illustrating this need through some examples from the Mediterranean basin. 相似文献
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The hyporheic zone (HZ) has the capability to eliminate and attenuate nutrients and contaminants in riverine systems. Biogeochemical reactions and the potential elimination of contaminants are strongly controlled by the flow paths and dynamics in the HZ. Nevertheless, an easily applicable method for the field determination of flow patterns in the HZ is still lacking. Therefore, a heat pulse technique, which traces the movement of a short heat pulse in the upper part of the HZ and other sand beds, was developed. Five rods are vertically driven into the sediment of the streambed; one rod with a heater as point source located in about 10‐cm sediment depth and four rods with four temperature sensors in 3 cm distance, arranged concentrically with 7 cm diameter around the heating rod. Subsequently, a heat pulse is applied and the resulting breakthrough curves are indicative of flow velocities and flow directions in the streambed. A rough data analysis procedure is also suggested. In addition, laboratory experiments were performed to test the heat pulse technique. These experiments were validated based on coupled numerical modelling of flow and heat transport. First field tests of the method prove that the method is easily applicable under field conditions. These first field tests showed highly complex flow patterns with flow velocities from 1·8 to 4·9 cm min?1 and flow directions from parallel to surface flow to opposite to surface flow. This suggests the need for a robust method to quantify hyporheic flow patterns in situ. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
70.
Ulrich Noseck Eva-Lena Tullborg Juhani Suksi Marcus Laaksoharju Václava Havlová Melissa A. Denecke Gunnar Buckau 《Applied Geochemistry》2012
This paper gives an overview of the behaviour of U in two natural systems, the Forsmark site (a granitic system) in Sweden and the Ruprechtov site (a Tertiary sedimentary system) in the Czech Republic, which have been investigated in the frame of the FUNMIG project. It is not a full review paper on U geochemistry. It shows how different approaches and methods have been used to derive information on U solubility and speciation, on characteristics of key processes as well as on timescales of these processes and accordingly information on the long-term stability of U phases in the natural systems. The results are set in a wider context by relation to selected results from other sites. 相似文献