investigation the concentration of heavy metals in the sediment of zayandehrood river bed

objective: zayandehrood habitat has economical and environmental importance in central plateau of iran    and it performs a vital role for habitants, agriculture section and the industries which are located along river bed. so current research  has been done to measure the contamination of heavy metals, its changes along the river route and defining the important and effective regions on this contamination. it was defined and stations of sampling along the zayandehrood river route to gain this aim. methods: the samples were taken from the depth of 30 to 50 cm of the substances which are located in river bed. in each sample, the absorbable thickness and whole metals of lead, cadmium, cobalt, nickel and copper were measured. the maximum thickness for all studied elements in this station was observed after isfahan city (isfahan-yazd highway bridge). among these heavy elements, the thickness absorbance amount for lead metal in 6 stations was in toxic amount. the thickness of cobalt in 5 stations and copper in one station was in toxic amount. the absorbance amount of lead in dorche bridge was 2.5 times and in yazd-isfahan highway bridge was 3.5 times more than the toxic amount.  results: according to the results of this research and according to other researcher’s studies, cadmium metal which has special importance because of its pollution on the environment has pot and toxicity along the river route, but the studies have been done via other researches in gavkhooni pond, have registered the toxicity amount of this element.               we can conclude that isfahan city and also the region which is the center of big industrial factories near nekouabad dam and polchalleh, have the most pollutant effects on zayandehrood habitants.