Modeling the feasibility of strontium remobilization from goethite surfaces in a saturated tuff at Yucca Mountain, Nye County, Nevada


Craig Alan Dicke, B.S.


presented to the Faculty of the Graduate School of 

The University of Texas at El Paso

in Partial Fulfillment

of the Requirements

for the Degree of 

Master of Science

The University of Texas at El Paso

May, 1988

8.0 Summary and Conclusions

(page 105)

The adsorption behavior of strontium has been studied for a simple chemical system with goethite as the adsorbent. For this system, which contained sodium, calcium, carbonate, and sulfate, the adsorption of strontium is most profoundly affected by the concentration of sulfate in the system. Increasing sulfate concentrations above 10-4 M causes a significant increase in the amount of adsorbed strontium. The increase is due to the changes in the electrostatics in the charge cloud. Decreasing the concentration of sulfate may cause desorption of strontium because of destabilization of the charge cloud.

Decreasing the calcium concentration in the system slightly increases the amount of strontium adsorption. This is probably a result of cations moving into the charge cloud to maintain a balance of charge.

Transport calculations under expected Yucca Mountain conditions display that it is possible to develop migration fronts by desorbing strontium (or other contaminants) as a result of charge cloud destabilization due to calcium concentration variations. Also, contaminant front development does not have to be associated with low pH fronts. Calculations for a potential migration scenario showed that more strontium is removed by fronts in which the pH is reduced due to the decay of sulfate surface complexes.