E.C.V. Butler: The Tail of Two Rivers in Tasmania: The Derwent and Huon Estuaries -- B. Knoppers, P.R. P. Medeiros, W. F. L. de Souza, and T. Jennerjahn: The São Francisco Estuary, Brazil -- J.M. Smoak- J.M. Krest -P.W. Swarzenski: Geochemistry of the Amazon Estuary -- R.W. Macdonald and Y. Yu: The Mackenzie Estuary of the Arctic Ocean -- C. Gobeil: Biogeochemistry and Chemical Contamination in the St. Lawrence Estuary -- W. Hamza: The Nile Estuary -- A. Provini and A. Binelli: Environmental Quality of the Po River Delta -- P. Viaroli, G. Giordani, M. Bartoli, M. Naldi, R. Azzoni, D. Nizzoli, I. Ferrari, J. M. Z. Comenges. S. Bencivelli, G. Castaldelli, E. A. Fano: The Sacca di Goro Lagoon and an Arm of the Po River -- N. Berlinsky, Y. Bogatova, G. Garkavaya: Estuary of the Danube -- J.-L. Gonzalez, B. Thouvenin, C. Dange, J.-F. Chiffoleau, B. Boutier: Role of Particle Sorption Properties in the Behavior and Speciation of Trace Metals in Macrotidal Estuaries: The Cadmium Example. Aspects of the biogeochemistry of estuaries from a variety of environments, from the tropics to the Arctic, are discussed. In most cases the courses of these rivers have been altered by dams or diversions; the results of these changes on the nature of the estuary are also discussed, where such data is available. In the case of the Tasmanian rivers, the estuary of the Huon, a largely untouched river, is contrasted with that of the Derwent, a river heavily influenced by industry. The future state of all of these estuaries may be a sensitive indicator of shifts in global weather patterns.