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In this study, the concentrations of some heavy metals in surface sediments of Naibandmarine national Park (the first marine national park of Iran) have been evaluated.Surface sediment sampling was done from July 2010 to March2011. Sediment sampleswere collected from the tidal zone of Mangrove ecosystem in 5 different stations. At each station, sampling was repeated three times, and the sediments were digested by acid after drying. Concentration of Cd, Ni, Pb and Cu was measured by atomic absorption spectrophotometer, Varian 200 Perkin Elmer. Results showed that Cd, Ni, Pb and Cu concentration in the sediments were 0.2(0.4-0.07), 40.1(94.03-14.6), 52.23 (64.6-40.2) and 5.2 (8.01-2.8) mg/kg respectively. All metals concentrations ofdry season werehigher than the metals concentration of the rainy season. Data were analyzed using SPSS16 software. Muller geochemical indicators (Igeo) and (Ipoll)indices were used as pollution index to classifying of sediments quality. Based on these indicess, sediments were moderately polluted by Pband unpollutedfor the other metals. Alsocompare of the metals concentrations to Sediment Quality Guidelines (SQG) showedno metal pollution for Cd and Cu and moderate level of pollutionfor Ni and Pb.

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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.

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The present study aimed to fractionation and determination of the most appropriate metals interpolation method such as zinc, copper and iron in surface sediments in range of Shadegan wildlife refuge was done for locating the polluted areas. Study and checking the total concentration and bioavailability of these elements in surface sediments and achieving the correct spatial distribution of pollutants based on the total concentration and their origin was carried out by sampling of 160 stations in three parts (northern, central and southern) of refuge from 0-5 cm of the surface layer of sediment due to the marshland of some areas of the wetland and the lack of access to these areas in May and November of 2014. The total concentrations of metals were analyzed in surface sediments by direct aqua regia method and their values were evaluated in sediment geochemical phases using 4-step sequential extraction method, while interpolation and modeling of spatial variations of metal concentrations in sediments through ordinary Kriging methods, radial basis function (spline) and inverse distance weighting (IDW) were drawn in Arc GIS and their accuracy compared by using error correction criteria RMSE and MAE and most useful method was selected. Maps of the distribution of concentrations of zinc and copper were prepared by using ordinary Kriging (OK) with exponential model for zinc and copper and by using of inverse distance weighting (IDW) for the iron. Sediments geochemical analysis results showed average concentrations of metals copper, zinc and iron, were obtained respectively 22.86, 55.20, 25979.01 microgram per gram of dry weight and natural fraction in ratio to the total concentration is allocated more than 89% percent and man-made fraction more than 10% of the total amount of all elements that studied in sediments of the stations studied. In addition, the amount of elements in the exchange phase was less than 3%, which was considered negligible. On the other hand, the analysis of the zoning map of heavy metals according to their chemical speciation showed that the highest bioavailability of zinc in the northern, southern and western parts has happened and the accumulation of copper and iron are visible respectively more in the western part for copper and central and northern parts for iron.