HR: 1340h
AN: H23G-1714    [Abstracts]
TI: Laboratory Assessment of Variable Retardation of a Reactive Solute in Stratified Geomedia
AU: * Leecaster, K
EM: leekevi@if.uidaho.edu
AF: University of Idaho, 1776 Science Center Drive, Idaho Falls, ID 83402, United States
AU: Smith, R W
EM: smithbob@uidaho.edu
AF: University of Idaho, 1776 Science Center Drive, Idaho Falls, ID 83402, United States
AB: The migration of solutes through heterogeneous geomedia is of interest to a variety of disciplines. The movement of a reactive solute relative to water is characterized by a retardation factor (R_f); the ratio between the travel times of the reactive solute and the bulk solution. Although the retardation factor is often treated as constant, for heterogeneous media it can be a function of the travel distances. We have conducted a series of tracer breakthrough experiments using a small two-dimensional flow cell with idealized layered chemical heterogeneity constructed from naturally metal (hydr)oxide coated sands of different facies from an Atlantic coastal formation near Oyster, VA. Reactive tracer pulses from1 from one pore volume through step breakthrough were applied to simulate different travel distances with flow directions both parallel and perpendicular to layering. Method of moments determination of mean breakthrough time demonstrates that R_f is an anisotropic property and it decreases with travel distance (i.e., smaller applied pulse of tracer) when flow is parallel to layering. These results highlight the need for detailed geologic delineation of the subsurface for accurate prediction of contaminant breakthrough and risk analysis.
DE: 1829 Groundwater hydrology
DE: 1832 Groundwater transport
DE: 1839 Hydrologic scaling
SC: Hydrology [H]
MN: 2007 Fall Meeting