Non-linear Release of Metals from Aquatic Sediments

Modern research on particle-bound contaminants quite probably originated with the idea, that sediments reflect the biological, chemical and physical conditions in a water body (Züllig 1956). Based on this concept, the historical evolution of limnological parameters could be traced back from the study of vertical sediment cores. In fact, already early in this century, Nipkow (1920) suggested that the alternating sequence of layers in a sediment core from Lake Zürich might be related to variations in the trophic status of the lake system. Geochemical investigations of stream sediment has become standard practice in mineral exploration since the beginning of the sixties (Hawkes and Webb 1962). Similarly, lake sediment geochemistry has been used as a guide to mineralization, particularly intensive on lakes of the Canadian shield. This approach attracted even more attention when mineral exploration was followed by large-scale mining and processing activities: “Both the exploration and environmental geochemist can be looking to the same type of areas, those with high metal concentrations, but obviously from a different motivation” (Allan 1974). During the past 20 years, research on metal-contaminated sediments evolved to four aspects, which in an overlapping succession also reflect the development of knowledge on particle-bound pollutants: The evaluation of solid/solution relations of metals in surface water;The study of in situ processes and mechanisms of metal transfer in various compartments of the aquatic ecosystems;The assessment of the environmental impact of particle-bound metals, i.e. development of sediment quality criteria;The development of remedial measures, in particular, of dredged materials, by integrated, multidisciplinary research