The mechanisms controlling the transport of three heavy metals: cadmium, chromium, and silver, in natural water systems are evaluated following a review of the scientific literature and laboratory studies of adsorption/desorption behavior and the interaction of these metals with phytoplankton. In fresh water, chromium as chromate is not appreciably taken up by model inorganic or organic particulates, but after reduction to Cr(III) is rapidly and irreversibly taken up by clay particles, hydrous iron oxide and phytoplankton. Cadmium and silver are more reversibly adsorbed by clay particles, are strongly adsorbed by hydrous manganese oxide, and are concentrated by phytoplankton. Once a part of reducing bottom sediments, the availability of all three metals to the aqueous phase is further reduced so that they are not released by short term resuspension. With prolonged resuspension of anoxic sediments some cadmium may redissolve, but chromium and silver will remain in the solid phase. (Author).

Over the past decade the sediments of many rivers, lakes, and estuaries have been contaminated by inorganic and organic materials. Contaminants from sediments, under certain conditions, can be released into overlying waters. Thus, sediments may be an important source of contaminants to waters in which littoral and atmospheric contaminants have been reduced or eliminated. Often found in aquatic sediments, metals are exposed to many reactions, such as sorption and precipitation, and are greatly influenced by the redox conditions in the sediment. The reactions - usually over a period of time - reflect biotic processing as well as chemical transformations. This book describes these important processes. Metal Contaminated Aquatic Sediments outlines advances in environmental chemistry, effective new modeling techniques, applications for biological treatment, and cycling and transport of trace metals in sedimentary environments. Each chapter contains a detailed reference section that draws upon a stunning array of sources. The book includes many figures and tables that illustrate the process under discussion. Features

Aquatic chemistry is becoming both a rewarding and substantial area of inquiry and is drawing many prominent scientists to its fold. Its literature has changed from a compilation of compositional tables to studies of the chemical reactions occurring within the aquatic environments. But more than this is the recognition that human society in part is determining the nature of aquatic systems. Since rivers deliver to the world ocean most of its dissolved and particulate components, the interactions of these two sets of waters determine the vitality of our coastal waters. This significant vol ume provides not only an introduction to the dynamics of aquatic chem istries but also identifies those materials that jeopardize the resources of both the marine and fluvial domains. Its very title provides its emphasis but clearly not its breadth in considering natural processes. The book will be of great value to those environmental scientists who are dedicated to keeping the resources of the hydrosphere renewable. As the size of the world population becomes larger in the near future and as the uses of materials and energy show parallel increases, the rivers and oceans must be considered as a resource to accept some of the wastes of society. The ability of these waters and the sediments below them to accommodate wastes must be assessed continually. The key questions relate to the capacities of aqueous systems to carry one or more pollutants.

This important volume-the product of a meeting of a select group of scientists-provides the most recent research results from the world's leaders in the study of toxic pollutants in sediments. It gives practical information on measuring and mapping distributions of concentrations of pollutants and their toxic effects in sediments. Also covered are the use and relative advantages and disadvantages of benthic chambers, sedimentation traps, box corers, "peepers" and other sampling techniques in sediment research and assessment. Important topics covered include: bioassay, elemental speciation, diffuse source problems, nutrient flux, biomethylation, bioavailability, and toxicity assessment. Will help in assessment and monitoring of chemistry, dynamics, bioavailability, and toxicity of pollutants, as well helping to chart courses for remedial action. This book will be of interest to anyone interested in the processes controlling the chemistry and movement of pollutants in sediments, especially: limnologists aquatic toxicologists engineers lake managers ecologists biologists environmental chemists

This book highlights the latest research on dissolved heavy metals in drinking water and their removal.