Assessment of pollution, bioavailability and bioaccumulation of heavy metals in sediment and razor clam, Solen dactylus in the western and eastern estuaries of Hormozgan province

The aim of this study was to determine the concentration of heavy metals in the sediments and the bivalve molluscs, Solen dactylus, in the estuaries covered by mangrove trees of west (Khamir estuary) and east (Shahrno estuary-Jask) of Hormozgan province and also to assess the pollution, bioaccumulation and toxicity of heavy metals (Fe, Ni, Cu and Pb), in these areas. Sediments were studied to determine the grain size, organic carbon, organic matter, total and partial concentration and bioavailability of metals. The results showed that the environmental factors such as organic matter and grain size of sediments affect the distribution of heavy metals. According to the results, there was no significant difference between the sediments of two stations in the accumulation of metals (P>0.05). contamination and enrichment factors for Ni and Pb showed a moderate degree of contamination and enrichment. The geochemical speciation of the studied metals indicated more bioavailability for Cu and Pb. The Risk Assessment Code and the screening quick reference table (SQRT) indicate the high risk in Cu for Shahrno estuary and in Pb for Khamir estuary, and both metals are above the threshold effect level (TEL) for the clam in the area. The results of S. dactylus's bioaccumulation factor showed that Cu accumulated more than other metals in both regions. In general, the present study showed that the sediments of the studied areas are contaminating in terms of Cu and Pb.