evaluation of heavy elements contamination and its relationship with aggregation in the sediments of kardeh reservoir

today, water resources stored in reservoirs is one of the basic sources of drinking-water. the elements in the sediments of reservoirs are the most important factors affecting water quality. unlike the primary plan, due to water shortage problems, nowadays, almost all the stored water in the kardeh reservoir is allocated to drinking water. from the other side in the catchment area of this dam a lot of changes in terms of land use, the development of agricultural lands and the construction of the garden-villa has taken place. therefore, surveying the status of the reservoir sediment contamination by heavy metals is essential. in this research, first some cores of sediments from the reservoir was taken and the amounts of 9 heavy metals elements in the sediments were determined using icp-oes. reservoir sediment contaminations by heavy metals were studied, by using qualitative criteria of sediments. then determine the aggregation of sediments by nano particle size analiyzer machine, the relationship between the particle size with the amount and the type of heavy elements present in the sediments were studied. based on the standards criteria, almost all the elements are at the acceptable ranges. it seems that the origin of these elements has been the local pollutants and not from sediments resulting from the transfer of the geological structure of the upstream areas. on the other hand trend of changes in particle size in the reservoir reflects the impact of flushing.