As only a few books have been published on the matter of toxic materials in water it occurred to the author that a comprehensive volume dealing with all aspects of this subject was overdue. In this book there is a complete discussion of world literature on the determination of metals, non-metals, organic substances, organometallic compounds, together with organic carbon parameters and radioactive elements in river, stream, lake and pond sediments, marine and estuarine sediments, river and sea fish, crustacea and molluscs, phytoplankton and sea and river weeds. Much very detailed work has been carried out on this subject over the past 20 years and a review of this work is timely in view of the increasing interest to chemists, environmentalists and others concerned with the quality of our environment. The presence of organic and inorganic substances in river and oceanic sediments is due in part to man-made pollution, and monitoring the levels of these substances in sediment and sediment core samples provides an indication of the time dependence of element concentration over large time spans. Contamination of sediments is found not only in rivers but also in estuarine sediments and sometimes in oceanic sedi­ ments, and this sediment analysis provides a means of tracking elements from their sources through the ecosystem.