Factors affecting the Distribution of some Heavy Metals with Geo-pedological Conditions in different soils near Zanjan province

The present study was aimed to evaluate role of Pedogenesis factors and Geo-pedological conditions on Distribution and Chemical speciation of some heavy metals. For this purpose, number of 15 profiles on different parent materials include Granite (Gr), Basalt (Ba), Andesite (An), Porphyritic (Pr ), Volcanic tuff (Tu) Limeston (Li), Conglomerates (Cg), Shale (Sh), Phyllites (Ph), Sandstone (Sa), Dolomite (Do) and Alluvium (Qa) were excavated around in Zanjan. The concentration and distribution of the elements Cr, Co, Cd, Zn and Pb are more controlled by lithogenic factors while elements Cu, Mn and Ni were affected by bio-geochemical processes factors. Depletion rate was obtained in order of following: (Zn>Co>Cd=Pb>Mn=Cr=Ni=Cu). In the early stages of pedogensis, bedrock and minerals and in its later stages, some soil processes such as calcium carbonate equivalent (CCE), acidity (pH), organic matter and clay create different patterns of enrichment-depletion. Distribution of elements in Entisols, Mollisols and Inceptisols, respectively, were controlled by parent material lithology, organic matter and redistribution calcium carbonated. In Sequential extraction, residual fraction was dominant component in all elements. For cobalt, nickel oxide fraction, for lead carbonate fraction, for copper and zinc, organic fractions were observed. Mobility factor for various elements in the surface horizons were (Pb>Co>Ni>Cu>Zn), respectively. results of extract measured by DTPA-extractible in various elements for lead, copper, nickel, zinc and cobalt were, 2.04, 1.81, 0.84, 0.42 and 0.30 mg/kg respectively and the highest value was observed in surface soil horizons