CONTAMINANT ACCUMULATION DURING TRANSPORT THROUGH POROUS-MEDIA

When a soil, rock, or sediment is exposed to changes of its chemical environment, that is, by infiltration of water, the new chemical composition propagates as a wave through the medium. Adsorbed contaminants may desorb behind the front of this remobilizing wave. If the velocity of the front is intermediate between the contaminant velocities upstream and downstream of the front, the remobilized contaminant accumulates at the front. The behavior of adsorbates on oxides under these circumstances is discussed. The analysis suggests that contaminant adsorption isotherms are insufficient to characterize the potential hazard associated with a contaminated soil or sediment. The additional data needed are the velocities of the possible remobilizing waves. Copyright 1990 by the American Geophysical Union.