Research on the transport and accumulation of toxic metals will demonstrate that an important role is played in the concentration of metals in aquatic media by the fine-grain sediments (clay minerals). Their large specific surface area with a high concentration of active sites is especially important in bonding of metals by adsorption, in ion exchange, in co-precipitation processes and in chelation on the surface of particular matter. Suspended solid phase carried by the water flow and bottom sediments, primarily the fine-grained portion, are considerable hydrochemical significance in the process of distribution and transportations of pollutants. These componentes are a heterogeneous mixture of amorphous and crystalline phases, whose composition is given by the source rocks and the processes occurring after deposition of the river sediments. The contamination of the bottom sediments of Czech rivers has received little attention in the past, although these river drain a region with a rich highly developed chemical and machine industries, with a rich history of mining of metallic ores, and with dense residential areas and high surface contamination. The sedimentation of deposits in artificial water reservoirs has, besides siltation, also other negative effects.