Particulate Transport of Cesium in Groundwater

Abstract

The migration of cesium-137 fixed to fine particles is suggested as one mechanism to explain the anomalous behaviour of cesium-137 released from glass blocks buried below the water table at Chalk River. A cesium-137 plume of low activity has been noted which extends at least four times further than predicted by a 1-D ion exchange equilibrium model. Soil columns prepared from undisturbed horizontal cores taken adjacent to the glass block site and spiked with cesium-134 have been used to show that low levels of cesium-134 are continuously released from the columns. Further, the cesium-134 is associated with particles 0.2 to 1.0 micrometer in size which are generated in and released from the column. Cobalt-60 gamma-irradiation experiments have shown that microorganisms are involved in the release or formation of particles associated with the transport of cesium-134 from the columns. The particulate transport of low levels of radiocesium from waste management areas may become a significant pathway for biosphere interaction in the case of high level waste management areas containing large amounts of radiocesium.