chemical partitioning & pollution intensity of heavy metals in siahrud river sediment

in the recent years, sediments are used for the assessment of pollution. since sediments have been in contact for a long time with over lying water, therefore they have been able to adsorb pollution on to their surface. in the present investigation, the surficial sediments of siahrud river have been analyzed. the loose, sulphide and organic bonds of metals with various sedimentary phases has been assessed by chemical partitioning technique. the sum of these three bonds is indicative of anthropogenic source of metals into the river. the lithogenic portion of metals were obtained by a two step chemical partitioning technique. the anthropogenic portion of metal contents in river sediments shows the following pattern: pb(85%)>zn(84%)>cd(62%)>as(47%)>mn(35%)>ni(34%)>cu(21%) the inter-relationship amongst various metal bonds were assessed by cluster analysis. the results show that bio-availability of metals such as cd, zn and as are highly dependent on anthropogenic portion and specially loosely bonded ions of such metals. the over all pollution intensity was obtained by various pollution intensity indices. the pollution intensity of zn and pb in the sediments of siahrud river are 3.572 and 3.148, respectively that are indicative of high pollution intensity. other studied metals fall within “no pollution” to “low pollution” intensities.