Held in 1993 in Niterói, Brazil, the first International Conference on Environmental Geochemistry in Tropical Countries established a starting point for this book. The book opens with a discussion of the points that arose during the closing session, summarised by Dr. E.K. Duursma: The Environment in the Tropics Remains Unknown. Most of the processes that occur in temperate environments turn out to be completely different in the tropics. This can already be seen in Chapter 3, where estimates of radionuclide transfer factors reach values considerably greater than in temperate areas. The utilisation of variables measured in temperate environments for modelling of the tropics can result in completely erroneous conclusions and, worse, inefficient remediation solutions.