Variation in Partition Coefficient, Kd, Values
This three-volume report describes the conceptualization, measurement, and use of the partition (or distribution) coefficient, Kd, parameter. It also describes the geochemical aqueous solution and sorbent properties that are most important in controlling adsorption/retardation behavior of selected contaminants.
The report is provided for technical staff from EPA and other organizations who are responsible for prioritizing site remediation and waste management decisions. It was a collaborative effort among EPA's Office of Emergency and Remedial Response, Office of Radiation and Indoor Air, and the Department of Energy's Office of Environmental Restoration.
On the page:
- Volume I - Kd Model, Measurement Methods, and Application of Chemical Reaction Codes [EPA 402-R-99-004A], 1999
- Volume II - Geochemistry and Available Kd Values for Selected Inorganic Contaminants [EPA 402-R-99-004 B], 1999
- Volume III - Review of Geochemistry and Available Kd Values
for Americium, Arsenic, Curium, Iodine, Neptunium, Radium, and Technetium[EPA 402-R-99-004C], 2004
You will need Adobe Reader to view some of the files on this page. See EPA's PDF page to learn more.
Limited print editions of this report may be obtained from the National Center for Environmental Publications.
Volume I - Kd Model, Measurement Methods, and Application of Chemical Reaction Codes
Volume I discusses the technical issues associated with the measurement of Kd values and its use in formulating the retardation factor, Rf. The Kd concept and methods for measurement of Kd values are discussed in detail in Volume I. Particular attention is directed at providing an understanding of: (1) the use of Kd values in formulating Rf, (2) the difference between the original thermodynamic Kd parameter derived from ion-exchange literature and its "empiricized" use in contaminant transport codes, and (3) the explicit and implicit assumptions underlying the use of the Kd parameter in contaminant transport codes.
A conceptual overview of chemical reaction models and their use in addressing technical defensibility issues associated with data from Kd studies is presented. The capabilities of EPA's geochemical reaction model MINTEQA2 and its different conceptual adsorption models are also reviewed.
The report is available below in sections and as a single file.
|Introduction||Cover, Foreword, Table of Contents (PDF) (15 pp, 53K)|
|Chapter 1||Introduction (PDF) (3 pp, 20K)|
|Chapter 2||The Kd Model And Its Use In Contaminant Transport Modeling (PDF) (43 pp, 2MB)|
|Chapter 3||Methods, Issues, and Criteria for Measuring Kd Values (PDF) (33 pp, 335K)|
|Chapter 4||Groundwater Calibration Assessment Based on Partition Coefficients: Derivation and Examples (PDF) (15 pp, 103K)|
|Chapter 5||Application of Chemical Reaction Codes (PDF) (51 pp, 212K)|
|Chapter 6||References (PDF) (26 pp, 76K)|
|Appendix A||Acronyms, Abbreviations, Symbols, and Notation (PDF) (40K)|
|Appendix B||Definitions (PDF) (26K)|
|Appendix C||Standard Method Used at Pacific Northwest National Laboratory for Measuring Laboratory Batch Kd Values (PDF) (55K)|
|Complete Report||Complete Report (all sections) (PDF) (212 pp, 2.65MB)|
Volume II - Geochemistry and Available Kd Values for Selected Inorganic Contaminants
Volume II provides a "thumb-nail sketch" of the key geochemical processes affecting the sorption of selected inorganic contaminants, and a summary of Kd values given in the literature for these contaminants under oxidizing conditions. Important aqueous speciation, (co)precipitation/dissolution, and adsorption reactions are discussed for each contaminant. References to related key experimental and review articles for further reading are also listed.
The contaminants discussed in Volume II include:
The report is available below in sections or as a single file.
Volume III - Review of Geochemistry and Available Kd Values for Americium, Arsenic, Curium, Iodine,
Neptunium, Radium, and Technetium
This is the third volume in the series that describes: (1) the conceptualization, measurement, and use of the partition coefficient parameter; and (2) the geochemical aqueous solution and sorbent properties that are most important in controlling adsorption/retardation behavior of selected contaminants.
The contaminants discussed in Volume III include:
Generic or default partition coefficient values found in the literature can result in significant errors when used to predict the impacts of contaminant migration or site-remediation options. For site-specific calculations, partition coefficient values measured at site-specific conditions are absolutely essential.
For those cases when the partition coefficient parameter is not or cannot be measured, Volumes II and III of this document:
- provide a “thumb-nail sketch” of the key geochemical processes affecting the sorption of the selected contaminants
- provide references to related key experimental and review articles for further reading;
- identify the important aqueous- and solid-phase parameters controlling the sorption of these contaminants in the subsurface environment under oxidizing conditions; and
- identify, when possible, minimum and maximum conservative partition coefficient values for each contaminant as a function of the key geochemical processes affecting their sorption.