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 Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Plummer, M. A. Articles by Fox, D. T. Search for Related Content PubMed Articles by Plummer, M. A. Articles by Fox, D. T. GeoRef GeoRef Citation Agricola Articles by Plummer, M. A. Articles by Fox, D. T. Related Collections Radionuclides Diffusion Experiment Design Vadose Zone Processes and Chemical Transport

SPECIAL SECTION: UNDERSTANDING SUBSURFACE FLOW AND TRANSPORT PROCESSES AT THE IDAHO NATIONAL ENGINEERING & ENVIRONMENTAL LABORATORY (INEEL) SITE

Transport of Carbon-14 in a Large Unsaturated Soil Column

Idaho National Engineering and Environmental Laboratory, P.O. Box 1625, MS 2107, Idaho Falls, ID 83415-2107
^* Corresponding author (plumma{at}inel.gov).

Received 10 July 2003.

Wastes buried at the Radioactive Waste Management Complex (RWMC) of the Idaho National Engineering and Environmental Laboratory (INEEL) include activated metals that release radioactive ¹⁴C as they corrode. To test and refine transport predictions that describe releases to the environment with time, we conducted a series of transport experiments with nonreactive gas- and aqueous-phase tracers and inorganic ¹⁴C species in a large unsaturated soil column filled with sediment representative of that at the RWMC. The tracer tests, hydraulic measurements, and chemical monitoring provided constraints on physical transport parameters, water content, and aqueous–gas partitioning behavior. With those constraints, we estimated a solid–aqueous distribution coefficient for the sediment through inverse modeling of the ¹⁴C transport data, using both a simple gas-diffusion model and a multiphase flow and transport simulator (STOMP). Results indicate that ¹⁴C transport in this system is well described by a reactive gas diffusion model, with a pH-dependent retardation factor. Fitting transport simulations to the early-time transport data yielded K_d 0.5 ± 0.1 mL g^–1, while soil samples removed approximately 1 yr later yielded K_d values of 0.8 to 2.4 mL g^–1. These values are consistent with those derived from smaller-scale experiments, demonstrating that laboratory-based measurements provide a valid means of estimating transport behavior at much larger spatial and temporal scales. Assuming that ¹⁴CO₂ migration in the RWMC is dominated by gas transport, our results suggest that most ¹⁴C released from the RWMC would discharge to the atmosphere rather than to the underlying Snake River Plain aquifer.

Abbreviations: DIC, dissolved inorganic carbon • INEEL, Idaho National Engineering and Environmental Laboratory • LLW, Low-Level Waste • RWMC, Radioactive Waste Management Complex • SDA, Subsurface Disposal Area • STOMP, Subsurface Transport Over Multiple Phases [model]

This article has been cited by other articles:

				S. Hamamoto, T. Tokida, T. Miyazaki, and M. Mizoguchi Dense Gas Flow in Volcanic Ash Soil: Effect of Pore Structure on Density-Driven Flow Soil Sci. Soc. Am. J., February 15, 2008; 72(2): 480 - 486. [Abstract] [Full Text] [PDF]