VII

Preface

The present special issue of the Journal of Contaminant Hydrology contains a part of the papers presented in the 3rd International Conference on Chem- istry and Migration of Actinides and Fission Products (MIGRATION 91) in Jerez de la Frontera, October 21-25, 1991. The conference was focused on the following three research fields: (A) chemistry of actinides and fission pro- ducts in natural aquatic systems; (B) geochemical interactions and transport phenomena; and (C) data base development and modelling. The papers deal- ing with field C are compiled in this special issue, whereas the other contribu- tions to fields A and B are being published in a special issue of Radiochimica Acta. The proceedings of the two previous conferences are published in Radio- chimica Acta. The reason for publishing the contributions to Field C of the third conference in this issue is to make them available also to readers in the non-nuclear field, since these papers deal with geochemical and hydrological migration processes of contaminants in general.

The first migration conference was held in Munich, September 1987 (MIGRATION 87) and the second one (MICRATION 89) in Monterey, California, November 1989. The fourth conference (MICRATION 93) is being organized and will be held in Charleston, South Carolina. This biannual conference is held alternately in Europe and U.S.A. Its main objective is the timely exchange of scientific information relating to the interdisciplinary problems associated with long-term safety assessment of geologic disposal of nuclear wastes. Such information is, of course, beneficial to contaminant hydrology in general, contributing to the understanding of the migration behaviour of non-nuclear contaminants.

The review process for the papers included in this issue was carried out by well-known experts in the field, and coordinated by Dr. J. Hadermann, PSI, Switzerland, and Dr. B. Grambow at KfK, Germany. The preliminary organization of all contributed papers was made by Dr. J. P. Diaz-Guerra, scientific secretary of MIGRATION 91, in CIEMAT, Spain.

J. I. KIM Chairman of the MIGRATION Conference ISC Professor, Technical University of Munich, F.R.G.