HR: 1340h
AN: H33F-0541    [Abstracts]
TI: Multicomponent reactive transport in hydrodynamic and geochemical heterogeneous porous media
AU: Yang, C
EM: yang@iccp.udc.es
AF: University of La Corunia, Campus de Elvinia s/n, Corunia, 15192 Spain
AU: * Samper, J
EM: jsamper@udc.es
AF: University of La Corunia, Campus de Elvinia s/n, Corunia, 15192 Spain
AB: Methods for analysing groundwater flow and transport in heterogeneous porous media usually focus on the heterogeneity of hydrodynamic parameters. Recent studies have addressed the effects of spatial heterogeneity of transport parameters for a single reactive species. On the other hand, sophisticated deterministic numerical models have been developped for the analysis of multicomponent reactive solute transport. Most of these models account for spatial heterogeneity by parameter zonation. Here we present the results of Montecarlo simulations for the transport of multicomponent chemically-reactive systems through hydrodynamic and geochemical heterogeneous porous media. One-dimensional transport of a set of chemical species suffering cation exchange takes place in a column of porous medium having random log-CEC (cation exchange capacity). This case corresponds to a laboratory column documented in PHREEQM user's manual. The column, initially filled with 1 mM NaNO3 and 0.2 mM KNO3, is flushed by 0.6 mM CaCl2 solution. Simulations of reactive transport have been performed with CORE2D V4. Statistical analyses have been obtained for the spatial distributions of cations and breakthrough curves at points located at increasing distances from the inflow boundary. log-CEC is assumed to be a random Gaussian function with a spherical semivariogram. Here we report the results for three cases: 1) Only heterogeneity in log-CEC with mild, medium and large variances (0.033, 0.1 and 1); 2) Only heterogeneity in log-K with variances of 0.01,0.1 and; and 3) Cross-correlated log-CEC and log-K. The heterogeneity in log-K affects the transport of all reactive and nonreactive species. Its effect increases with increasing log K variance. All species are "retarded" and show longer tails. The variability of CEC has a much smaller effect than the variability of log K. The combined effect of simultaneous heterogeneity in log-K & log-CEC produces much longer tails (especially for Ca) and larger concentration variances. The lack of cross-correlation causes a spread greater than that of possitively correlated K and CEC.
DE: 1829 Groundwater hydrology
DE: 1832 Groundwater transport
DE: 1869 Stochastic processes
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting