Alkaline-disturbed zone

Cement-equilibrated water derived from the repository will react with the surrounding rock and form an alkaline-disturbed zone (ADZ) around the repository. The main reactions that are expected to occur within the ADZ are dissolution of primary silicates, and precipitation of hydrated calcium silicates (CSH phases) and possibly zeolites (Rochelle et al. 1992). As such water-rock interaction proceeds, the pH of the repository-derived water will be buffered toward lower values and will eventually reach the nearneutral values typical of unperturbed far-field groundwaters. It is likely that the hydrogeological and radionuclide retardation properties of the ADZ will be different from those of the unperturbed geosphere. The NSARP therefore includes work to evaluate the size of the ADZ and the extent to which its properties will be perturbed. A summary of the ADZ sorption programme is presented below. 

Experimental simulation of the alkaline disturbed zone around a cementitious radioactive waste repository numerical modelling... 

Bateman, K., Coombs, P., Noy, D. J., Pearce, J. M. Wetton, P. D. 1998. Numerical modelling and column experiments to simulate the alkaline disturbed zone around a cementitious radioactive waste repository. Materials Research Society Symposium Proceedings, 506, 605-611. 

Coccidioidomycosis is caused by infection with Coccidioides immi-tis, a dimorphic fungus found in the southwestern and western United States, as well as in parts of Mexico and South America. In North America, the endemic regions encompass the semiarid areas of the southwestern United States from California to Texas known as the Lower Sonoran Zone, where there is scant annual rainfall, hot summers, and sandy, alkaline soil. C. immitis grows in the soil as a mold, and mycelia proliferate during the rainy season. During the dry season, resistant arthroconidia form and become airborne when the soil is disturbed. 

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