Introduction The Fourth Symposium on Sediment/Water Interactions was held in Melbourne, Australia, February 16-20th, 1987. The previous three symposia were held in Amsterdam, Kingston (Ontario), and Geneva, In keeping with the approach established in Geneva, contributions addressed sediment/water interactions related to both fresh and salt water conditions. More than 160 papers were given in Melbourne, including more than 20 poster presentations, and collected Abstracts are available from Dr. B. T. Hart. A total of 51 papers, subsequently, have been published as proceedings of the Melbourne Symposium; 45 of these appear in this issue of Hydrobiologia. A further six appeared earlier as a selection of papers in J. Environ. Geol. and Water Science (1988, issue # 1); these six papers appear in abstract form, only, in the present pUblication. Although concerned with the global environment, the International Association for Sediment Water Science attempts to ensure that there is a genuine opportunity for participants to focus on regional issues throughout the world and, in particular, to provide a local forum for their presentation. The Melbourne meeting was particularly successful in achieving this objective, and Australasia was well represented by about 36 percent of the contributors. About 27 percent were from Europe, 17 percent from North America, 7 percent from China and Japan, 7 percent from Southeast Asia and India, and about 6 percent came from other areas. In all, 25 countries were represented.

The papers appearing in this volume reflect the current attention in sediment/water science to five main topics of investigation: Sediment dynamics in estuaries, coastal waters, lakes, reservoirs and rivers; Sediment-associated biological processes; Contaminant accumulation, distribution and geochemistry; Fluxes from sediments; and Element cycling. Contributors address sediment/water interactions related to both fresh and salt water conditions.

The first symposium on sediment/freshwater interactions was held in Amsterdam, in 1976, and the second was held at Kingston, Ontario, Canada, in 1981. The third symposium was held at the University of Geneva, in 1984, and also included a num ber of contributions dealing with sediment/saltwater interactions. It is expected that future symposia of this series will retain this approach, and that the revised sympo sium title will remain the same for later proceedings of these meetings. Because of the large number of submissions in 1984, many were given as poster presentations. Extended abstracts of all contributions to the Geneva symposium appear in Interactions Between Sediments and Ubter (C. E. P. Consultants Ltd. , 26 Albany St. , Edinburgh, EHI 3QH, U. K. , 1984). Full-length papers appear only in the proceedings. The format of the third symposium was similar to its predecessors. The location provided a particularly good opportunity for attendance by European scientists, who represented about 81% of the participants. About 16% came from North America and 3% were from Southeast Asia and Australia. It is unfortunate that there were no contributors from either Africa or South America, or other parts of Asia. In all, 16 countries were represented at this symposium. In a continuing attempt to provide equal opportunities for attendance by scientists from other parts of the world, it is planned to hold the next symposium in Australia in 1987. Further information about the symposia series can be obtained from Dr. E. D.

See journals under US Geological survey. Circular 993.

Recent years have seen a paradigm shift in our understanding of groundwater–surface water interactions: surface water and aquifers were long considered discrete, separate entities; they are now understood as integral components of a surface–subsurface continuum. This book provides an overview of current research advances and innovative approaches in groundwater–surface water interactions. The 20 research articles and 1 communication cover a wide range of thematic scopes, scales, and experimental and modelling methods across different disciplines (hydrology, aquatic ecology, biogeochemistry, and environmental pollution). The book identifies current knowledge gaps and reveals the challenges in establishing standardized measurement, observation, and assessment approaches. It includes current hot topcis with environmental and societal relevance such as eutrophication, retention of legacy, and emerging pollutants (e.g., pharmaceuticals and microplastics), urban water interfaces, and climate change impacts. The book demonstrates the relevance of processes at groundwater–surface water interfaces for (1) regional water balances and (2) quality and quantity of drinking water resources. As such, this book represents the long-awaited transfer of the above-mentioned paradigm shift in understanding of groundwater–surface water interactions from science to practice.

Acknowledgements Conference Summary R. D. EVANS, A. PROVINI, J. S. MATIICE, B. T. HART and J. WISNIEWSKI/Interactions Between Sediments and Water: Summary of the 7th International Symposium 1-7 Sediment I Water Dynamics D. E. WALLING and W. HE /Investigating Spatial Patterns of Overbank Sedimentation on River Floodplains 9-20 R. JEPSEN, J. ROBERTS and W. LICK / Effects of Bulk Density on Sediment Erosion Rates 21-31 T. G. MILLIGAN and D. H. LORING / The Effect of Flocculation on the Size Distributions of Bottom Sediment in Coastal Inlets: Implications for Contaminant Transport 33-42 loG. DROPPO, G. G. LEPPARD, D. T. FLANNIGAN and S. N. LlSS / The Freshwater Floc: A Functional Relationship of Water and Organic and Inorganic Floc Constituents Affecting Suspended Sediment Properties 43-53 C. H. TSAI and J. Q. HU / Flocculation of Particles by Fluid Shear in Buffered Suspensions 55-62 P. M. STONE and D. E. WALLING / Particle Size Selectivity Considerations in Suspended Sediment Budget Investigations 63-70 Q. HE and D. E. WALLING / Spatial Variability of the Particle Size Composition of Overbank Floodplain Deposits 71-80 C. YEN and Y. LIN KEY / Variations of Bed Surface Sediment Size in a Channel Bend 81-88 M. STONE and B. G. KRISHNAPPAN / Transport Characteristics of Tile-Drain Sediments From an Agricultural Watershed 89-103 U. KERN and B. WESTRICH / Sediment Budget Analysis for River Reservoirs 105-112 A. I. PACKMAN, N. H. BROOKS and J. J.

This is the first interdisciplinary book on the mobilization of nutrients and pollutants in the water phase due to hydrodynamic processes. Coverage includes the formation of aggregates in turbulent water; flocks and biofilms from organic reactions; and the formation of new surfaces for re-adsorption of dissolved pollutants. The book gathers papers resulting from an International Symposium on Sediment Dynamics and Pollutant Mobility in River Basins in Hamburg, Germany, March, 2006.