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Adsorption-desorption processes in subsurface reactive transport modeling

Sabine Goldberg, Louise J. Criscenti, David R. Turner, James A. Davis and Kirk J. Cantrell
Adsorption-desorption processes in subsurface reactive transport modeling
Vadose Zone Journal (August 2007) 6 (3): 407-435


Adsorption-desorption reactions are important processes that affect the transport of contaminants in the environment. Various empirical approaches, such as the distribution coefficient and Freundlich and Langmuir isotherm equations, have been used to represent adsorption. The empirical approaches are not capable of accounting for the effects of variable chemical conditions, such as pH, on adsorption reactions. This can be done using chemical models such as surface complexation models. These models define specific surface species, chemical reactions, equilibrium constants, mass balances, and charge balances, and their molecular features can be given thermodynamic significance. Ion adsorption mechanisms and surface configurations for the surface complexation models can be established from independent experimental observations. These include both indirect measurements, such as point of zero charge shifts, ionic strength effects, and calorimetry, and direct spectroscopic techniques, including vibrational spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and X-ray absorption spectroscopy. Surface complexation models were developed for single mineral phases but have now been applied to natural mineral assemblages using both component additivity (CA) and generalized composite (GC) approaches. Surface complexation models have been incorporated into subsurface transport models at several field sites, although simplifying assumptions are needed to deal with heterogeneous materials. Surface complexation models for contaminant adsorption have the potential to increase the confidence and scientific credibility of transport modeling by reducing the uncertainty in quantifying retardation and providing a means of quantifying that uncertainty.

ISSN: 1539-1663
Serial Title: Vadose Zone Journal
Serial Volume: 6
Serial Issue: 3
Title: Adsorption-desorption processes in subsurface reactive transport modeling
Affiliation: USDA-ARS, Salinity Laboratory, Riverside, CA, United States
Pages: 407-435
Published: 200708
Text Language: English
Publisher: Soil Science Society of America, Madison, WI, United States
References: 274
Accession Number: 2007-107323
Categories: HydrogeologyGeneral geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: 4 tables
Secondary Affiliation: Sandia National Lab., USA, United StatesCenter for Nuclear Waste Regulatory Analyses, USA, United StatesU. S. Geological Survey, USA, United StatesPacific Northwest National Laboratory, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Soil Science Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200745
Program Name: USGSOPNon-USGS publications with USGS authors
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