The Norwich Symposium, 'Radionuclides in the Study of Marine Proces­ ses', is a sequel to the very successful conference held at Cherbourg, France in June 1987. The international character of the meeting has been maintained with thirty-eight contributions, from seventeen countries, being accepted for oral presentation. For many years, the radioactive properties of the naturally occurring radionuclides have been used to determine their distributions in the marine environment and, more generally, to gain an understanding of the dynamic processes which control their behaviour in attaining these distributions. More recently the inputs from human activities of both natural and artificial (i.e. man-made) radionuclides have provided additional opportunities for the study of marine processes on local, regional and global scales. Because the sources of artificial radionuclides are often reasonably well defined in space and time, and because a wider range of elements is represented, new viewpoints for the study of processes have become available. Although it is outside the scope of this Symposium, it must be acknowledged that the radiological protection requirements for radioactive waste disposal prac­ tices to be based on a sound scientific understanding of radionuclide behaviour in the sea have also provided a very strong impetus for the studies.