Near field geochemistry

Conditioning of the near field geochemistry by the canister corrosion processes... 

The engineered barriers of a repository (waste form, container, clay buffer and backfill material and repository stmcmre) which will degrade with time due to various physico-chemical processes, strongly affect the geochemistry of fluids and rocks of the near field environment (redox properties, sorption properties, solubility limits, equilibrium chemistry, etc.) and determine the speciation and the subsequent migration behaviour of the radionuclides into the far field. Extensive... 

Coombs, P., Gardner, S. J., Rochelle, C. A. West, J. M. 1998. Natural analogue for geochemistry and microbiology of cement porewaters and cement porewater host rock/near-field interactions. In Linklater, C. (ed.) A natural analogue of cement-buffered groundwaters and their interaction with a repository host rock II. Nirex Science Report, S-98-003. Nirex, Didcot, UK. 

The near-field geochemistry of HLW disposal in an argillaceous host rock. Nagra Technical Report Series NTB 88-26, Nagra, Wettingen, Switzerland. 

Until now, Mercury has only been studied more closely by one spacecraft (Mariner 10, 1974), since its nearness to the sun means that spacecraft approaching it are subject to particularly extreme conditions. NASA s MESSENGER (Mercury Surface, Space, Environment, Geochemistry and Ranging) was launched in 2004 and is planned to reach Mercury in March 2011, and then to orbit the planet. The main tasks of the MESSENGER mission are to map the planet, to make measurements of its magnetic field and to collect data relevant to its geological and tectonic history (Solomon, 2007). 

No doubt many discoveries will be made in the field of coordination geochemistry in the near future. This is only to be expected in the light of advances in techniques and instrumentation. 

Crystal field theory is one of several chemical bonding models and one that is applicable solely to the transition metal and lanthanide elements. The theory, which utilizes thermodynamic data obtained from absorption bands in the visible and near-infrared regions of the electromagnetic spectrum, has met with widespread applications and successful interpretations of diverse physical and chemical properties of elements of the first transition series. These elements comprise scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel and copper. The position of the first transition series in the periodic table is shown in fig. 1.1. Transition elements constitute almost forty weight per cent, or eighteen atom per cent, of the Earth (Appendix 1) and occur in most minerals in the Crust, Mantle and Core. As a result, there are many aspects of transition metal geochemistry that are amenable to interpretation by crystal field theory. 

The inverse fifth-power dependency of crystal field splitting on metal-oxygen distance expressed in eq. (2.17) is of fundamental importance in transition metal geochemistry, particularly in mineral physics at high pressures and interpretations of visible to near-infrared spectra of minerals. Thus, the A °= R 5 relationship, eq. (2.17), is referred to frequently in later chapters. 

Adsorption of ions onto alumina is a problem of great interest in very different fields. As can be seen from the journals mentioned in the reference list, it is important in geochemistry as well as in limnology, in pollution control as well as in catalyst preparation or soil chemistry, and sometimes even in unexpected disciplines such as nuclear techniques. The different applications lead to different questions and experimental conditions. For example, the "normal" concentrations are low in limnology and the pH is restricted to nearly neutral conditions. In contrast, in catalysis there are rather high concentrations and the pH, in principle, is variable, though sometimes not even discussed, probably as a consequence of the use of older technical impregnation techniques in which nonequilibrium conditions were applied. 

Jang, M. 2009. Application of portable X-ray fluorescence (pXRF) for heavy metal analysis of soils in crop fields near abandoned mine sites. Environmental Geochemistry and Health 32, no. 3 207-216. doi 10.1007/sl0653-009-9276-z. 

Tatsumoto, M. Isotopic composition of lead in the sediments near Japan Trench, Chap. 10 (179—184). In Recent Researches in the Fields of Hydrosphere, Atmosphere, and Nuclear Geochemistry, 404 p. Tokyo Maruzen Co. Ltd. 1964. 

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