The transport and retention of water, nutrients, and inorganic and organic contaminants in the environment is greatly affected by physical and chemical processes and reactions in porous media such as soils. To definitively and comprehensively understand and model these processes/reactions, it is important that multiple scales--ranging from the landscape to the molecular--be investigated. Over the past decade numerous developments at multiple scales, have occurred in the soil, physical, and environmental sciences. These developments, which are discussed in this book, include: employment of fractal and spatial heterogeneity analyses in describing transport phenomena; development of sophisticated molecular models; use of in situ spectroscopic and microscopic techniques to elucidate reaction mechanisms and models in soils; and, inclusion of time-dependent phenomena in predicting solute transport/retention in soils. This publication presents the state-of-the-art on physicochemical processes of water/solute transport/retention. Scientists, professionals, and students who are interested in aqueous and terrestrial ecosystems will find this publication to be quite beneficial. H. Magdi Selim and Donald L. Sparks, ed. Softcover, 280 pages, 2001; SSSA. SSSA Special Publication Number 56. ISBN 0-89118-835-5.