Effect of sedimentparticle diameter on accumulation levels of heavy metals in Surface sediments of Anzali wetland southwestern

Heavy metals are main environmental pollutants that result in pollution of aquatic ecosystems and enter food chain, by different environmental substance such as industrial wastewater and agricultural drains. The sediments are one of the most importantparts for storage of heavy metals in aquatic ecosystem. Accumulation levels of heavy metals in sediments rely on many environmental factors, such as size of particles, pH, type and concentration of organic matter and amount of heavy metals in environment.The aim of this research is study of effects of particle size on accumulation of heavy metals (Cr, Pb, Zn, Cu, Cd) in surface sediments. Sediments were sampled by Grap sampler from 6 stations in southwestern of Anzali wetland, in summer 1388. The evaluated concentration of metals in particles of 0.063, 0.25, 1 and 2 mm was carried. The average concentration resulted 1.45, 4.44, 39.18, 27.7 and 0.86 for Cr, Pb, Zn, Cu and Cd, respectively. These results showed that concentrations of metals were not upper than global standards, excepting cadmium that was in order of average pollution. As well as results detected significant effect of sediment's size of particles on accumulation heavy metals in particles 0.063 mm however this effect was not significant in other particles.