عنوان مقاله [English]
Natural lakes and artificial reservoirs (dams) are considered as reservoirs for storing water in the watershed area, as well as for the accumulation of fine sediments derived from the atmosphere, and thus containing valuable information on the time variations in these entrances. While the use of sediments of natural lakes as environmental documentation has been validated, the use of dam deposits (artificial lakes) as time records has been less frequent. But, apparently, for the purpose of examining the past pollution, artificial water resources are more attractive: these reserves are mostly located in proximity to cities and industrial pollutants, and sediments accumulate rapidly and simultaneously with the spread of contamination. The lack of interest in artificial reservoir sediments has been due to this view that the change in the level of water resources of these reservoirs is likely to cause considerable disturbance in reservoir sediments. This perception may be reinforced by the absence of research into sedimentary systems of artificial reservoirs. Therefore, there is a need for a revision of published research (relatively few studies that use sediments of artificial water reservoirs and studies on the literature of sediments of natural lakes) about the patterns and processes of artificial reservoirs, and thus, vitally assesses the potential and problems associated with the use of water deposits as time records of contamination. The current understanding of sedimentation processes and distribution of sediment resulting from those processes is revised. Some important differences between artificial and natural lakes are emphasized and the requirements for sampling and interpretation of sedimentary data are discussed. It is suggested that a valuable source is currently in use, and it is also shown that artificial reservoir sediment data can provide important data for understanding and reconstruction of atmospheric pollution and watershed of these resources.