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(M/FF246) Assessment of ecological quality of waters by degree of bottom sediments pollution. Ignatyeva, Natalia1, Efremova, Lyudmila1, Kondratyev, Sergey1, 1 ABSTRACT- Bottom sediments reflect most adequately the changes, which have happened in the water body during large time intervals, and serve as indicators of the level of external load on the water body and its ecological state. Besides, vertical distribution of pollutants accumulated in the sediments reflects history of technogenic pollution in case the water bodies are located within an urban area. An integrated index of bottom sediments pollution Zc, calculated based on the heavy metals content in the surface sediment layer, has been used as an integral characteristic of chemical pollution of 10 internal water bodies (lakes, ponds, reservoirs) of St.-Petersburg city (N-W Russia). It was found that the highest Zc values are referred to the water bodies, which accept polluted runoff and are characterized by highest level of sum external load. Most proportion of pollutants settles to the bottom being associated with particulate organic matter. The relationship between the values of Zc and organic matter content (by values of loss on ignition) in the studied water bodies of St. Petersburg has been found. The obtained relation can be used for express-estimation of sediments pollution degree based on the organic matter content in the bottom sediments of the water bodies of St. Petersburg area. Key words: sediment, pollution, water quality, heavy metals |
