R. Sims et al., URANIUM MIGRATION THROUGH INTACT SANDSTONE - EFFECT OF POLLUTANT CONCENTRATION AND THE REVERSIBILITY OF UPTAKE, Journal of contaminant hydrology, 21(1-4), 1996, pp. 215-228
Citations number
23
Categorie Soggetti
Water Resources","Environmental Sciences","Geosciences, Interdisciplinary
A series of core flood experiments has been performed to investigate t
he migration behaviour of uranium under rigidly controlled conditions.
Intact sandstone cores, pre-equilibrated with synthetic groundwater,
were flooded with uranium solutions at varying concentrations and the
transport process monitored as a function of pH, tracer concentration
and the concentration of a competing ion, cadmium. In each case a subs
tantial amount of uranium was retained by the core, implying a strong
interaction with the rock matrix. The adsorption process was found to
be highly concentration dependent; however, such that the finite reten
tion capacity of an intact core can be exhausted within a relatively s
hort time. The reversibility of uptake was studied by attempting to di
splace adsorbed uranium by injected cadmium and flushing with brine. M
ost of the uranium was readily recoverable but a small percentage is r
eleased very slowly on flushing, suggesting conversion to a more stabl
e form. Prior to performing each experiment a simulation was carried o
ut using a one-dimensional coupled chemical transport code, encompassi
ng a thermodynamic description of the electrical double layer. The mod
el was successful in predicting a priori the dominant trends in the ur
anium migration behaviour which may aid in model developments for more
complex geochemical regimes than those studied here.