Any concentration of a substance measured in a living or non-living system results from its distribution among all of the environmental compartments: air, water, sediments, and biota. The transfer of a substance from one compartment to another is regulated by physical forces and the chemical properties of the substance and also those of the compartments. When transfer processes are nearly constant in time, a substance will achieve predictable equilibria distributions. It is of utmost importance that students, environmental scientists, and policymakers understand the basic processes which control the distribution of a substance in order to interpret measurements obtained from within a limited number of compartments.

This preface is being written at a time of exceptional public interest in the North Sea, following media head lines on toxic algal blooms, the mass mortality of common seals, and concern over pollution levels. These headlines may suggest that pollution of the North Sea is a recent event. This is not the case. Although no data are available (methods simply did not exist), it is safe to assume that emission (both into air and water) of heavy metals already started to increase in the 19th cen tury. The growth of cities and introduction of sewer sys tems led to the discharge of raw sewage and sewage sludge. The introduction of man-made (xenobiotic) organ ic chemicals and their subsequent emission into the North Sea commenced before the second world war. The shallower and coastal areas of the North Sea receive the highest concentrations of these pollutants. Not unexpectedly, these areas - some Norwegian fjords, the Dutch coast, the German Bight - show signs of ecosystem deterioration and eutrophication. A certain percentage of the pollutants does not remain in the North Sea but is "exported" to the Atlantic. The North Sea therefore con tributes to the global input of pollutants to the world's oceans. The major part of the pollutants accumulate in the North Sea and are incorporated in the bottom sediments. Although they are "out of sight," they should not be "out of mind.""

Three symposia on environmental geochemistry in tropical countries, held in Niter6i, Brazil (1993), in Cartagena, Colombia (1996) and in Nova Friburgo, Brazil (1999), made it very clear that tropical geochemistry is of world standard and fast increasing in multi disciplinarily and impact on important geochemical paradigms. It has additionally strong links with the economy of tropical countries, such as mining and industrialisa tion and is in full development for treating environmental problems caused by human activities of urban or industrial origin. We must compliment Prof. Jorge Abriio and his colleagues in Brazil and Dr. Gloria Prieto and her colleagues in Colombia for these ini tiatives. The participation of respectively 180 and 150 scientists, coming from 15 different countries for the first and second symposia, has shown that a large interest exists for tropical environmental geochemistry. It also demonstrates the necessity to understand tropical environmental problems. The organisation of a large international symposium is not possible without the assistance of state and federal authorities, for which those of Brazil and Colombia have to be complimented. The 3rd Symposium on Environmental Geochemistry in Tropical Countries was the last of the series and was attended by 22 countries and 170 participants and treated a number of related environmental and economic problems."

This book incorporates twenty contributions on diverse aspects of the environmental geochemistry in tropical and sub-tropical environments, drawing together extensive original research not readily available elsewhere. Coverage includes intercontinental comparisons drawn on paleoclimatology, environmental impacts of mining and geochemistry of continetal shelf sediments.

The multidisciplinary character of this Encyclopedia of Marine Sciences (biology, chemistry, geology, physics in oceanography) is reflected in some 1980 up-to-date alphabetically listed keywords, and many illustrations, to give scientists, teachers, and students a helpful and time-saving aid when studying marine scientific literature. The brief explanation of the concepts, terminology and methods makes this book more valuable than just a glossary or dictionary.

Although leaked chemical warfare (CW) gases rapidly hydrolyse in sea water, potential risks of serious contamination will exist for many decades for sailors, fishermen and coastal visitors of the Baltic Sea and Skagerak, in particular concerning contact with lumps of mustard gas. Blue prints of emergency plans should be available in order to confine, bury or destroy ammunition at risk. For that reason bottom current maps should be available to predict the transport of lumps over the sea bottom. Test should be made in hydraulic laboratories about the correlation water current and lump transport. Modelling may predict the hotspots in the future. This is an updated document.