HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Related articles in JEQ Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (12) Citing Articles via Google Scholar Google Scholar Articles by Seuntjens, P. Articles by Geuzens, P. Search for Related Content PubMed PubMed Citation Articles by Seuntjens, P. Articles by Geuzens, P. GeoRef GeoRef Citation Agricola Articles by Seuntjens, P. Articles by Geuzens, P. Related Collections Vadose Zone Processes and Chemical Transport Water Quality Heavy Metals Water Pollution

TECHNICAL REPORT
Vadose Zone Processes and Chemical Transport

Aging Effects on Cadmium Transport in Undisturbed Contaminated Sandy Soil Columns

P. Seuntjens^a, K. Tirez^a, J. imnek^b, M.Th. van Genuchten^b, C. Cornelis^a and P. Geuzens^a

^a Vito, Flemish Institute for Technological Research, Boeretang 200, B-2400 Mol, Belgium
^b USDA-ARS, George E. Brown, Jr., Salinity Lab., 450 W. Big Springs Road, Riverside, CA 92507-4617

Corresponding author (piet.seuntjens{at}vito.be)

Received for publication June 14, 2000. Limited information is available on the effects of contaminant aging (i.e., the contact time of Cd with the soil) on Cd transport in soils. We conducted displacement experiments in which indigenous Cd and freshly applied Cd were leached simultaneously from undisturbed samples of three Spodosol horizons. Sorption of Cd was described using Freundlich isotherms, whereas transport was described as a convection–dispersion process. Parameter optimization analysis using a mobile–immobile transport model applied to nonsorbing tracer displacement data showed that 16 to 22% of the water in the columns was immobile. The low dimensionless mass transfer coefficients in the mobile–immobile model were indicative of diffusion-limited transfer between mobile and immobile water, and hence physical nonequilibrium. A two-site kinetic sorption model could be fitted closely to breakthrough curves of the non-aged Cd for three soil horizons. No conclusive evidence was found that contaminant aging in soil affects cadmium transport. On the one hand, predictions of aged Cd leaching, using parameters estimated from displacement experiments with non-aged Cd, differed from those for the aged Cd in the E horizon. On the other hand, no meaningful differences in transport behavior between aged and non-aged Cd were found for the humus Bh and Bh/C horizons. The two-site kinetic rate coefficient _c was found to depend on water flux, further indicating that mass transfer between sorption sites and the liquid is limited by diffusion rather than by kinetic sorption.

Abbreviations: 2SF, two-species Freundlich model • 3SF, three-species Freundlich model • BTC, breakthrough curve • CDE, convection–dispersion model • LEA, local equilibrium • TRM, two-region model

Related articles in JEQ:

This Issue in Journal of Environmental Quality

JEQ 2001 30: 677-682. [Full Text]