This book arises from a meeting of the same name held at the Postgraduate Research Institute for Sedimentology, Reading, UK, in April 1994. The meeting was sponsored by the Challenger Society and the Geochemistry Group of the Mineralogical Society: we are grateful to both these organisations for their generous support. Eight scientists active in research on the biogeochemistry of intertidal systems were invited to present papers on their own particular interests within the field. We deliberately selected a mixture of established and young UK scientists and invited them to both briefly review the field and to present some new data from their own research. These papers have now been formalised into this book together with an overview chapter written by ourselves. The various authors have taken different approaches to the task we set them: some have achieved a balance between review and current research, whereas others have chosen to concentrate mainly on either review or recent research. As editors we have encouraged their diversity, allowing the authors the freedom to deal with the subject as they see best. We wish to thank all the authors for their good humour and hard work. All the chapters have been peer reviewed so we are additionally grateful to D. Cooper, A. Grant, J. Hamilton-Taylor, D. Hydes, S. Malcolm, R. Mortimer, J. Scudlark and S. Wakefield. (Chapter one was reviewed by the authors of the other book chapters.)