An analysis of solute diffusion in the Culebra Dolomite
The diffusion of unreactive solutes through the Culebra Dolomite was studied experimentally and theoretically. The measured diffusive flux is less than that predicted from independent knowledge of the porosity and reasonable estimates of tortuosity. This low measured flux led to a review of the relationship between solute diffusion and pore geometry in rocks and sediments. Solute transport in hypothetical pore networks, where the effect of pore geometry on the solute flux is directly calculable, is examined. A conventional interpretation of pore tortuosity, as a normalized length of diffusion through a pore, loses meaning for cases where pores intersect in networks. Some important variables affecting the tortuosity are: (1) the distribution of pore sizes (2) the distribution of pore lengths, (3) the number of pores which intersect at a node, and (4) the pore shape between nodes. Furthermore, in porous materials with a preferential distribution of pore sizes and orientation, tortuosity is a tensor. For the Culebra Dolomite, the wide range of pore sizes causes the diffusive flux to vary considerably from that predicted from conventional theory. These results indicate that diffusive fluxes from fractures into rock pores may be smaller than previously thought. 35 refs., 10 figs., 2 tabs.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- Sponsoring Organization:
- DOE/ER
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5603465
- Report Number(s):
- SAND-89-0750; ON: DE90000900
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360603 -- Materials-- Properties
510200* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ALKALINE EARTH METAL COMPOUNDS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
DIFFUSION
DOLOMITE
ENVIRONMENTAL TRANSPORT
FAILURES
FRACTURES
ISOTOPE APPLICATIONS
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MASS TRANSFER
MATHEMATICAL MODELS
MINERALS
OXYGEN COMPOUNDS
POROSITY
RADIONUCLIDE MIGRATION
SOLUTES
TRACER TECHNIQUES