toxicology. Considering the specific conditions of the Persian Gulf and the impact of pollutants, the aim of the present study was to evaluation of toxic elements bioavailability from the total amount of surface sediments in the Persian Gulf.
Materials & Methods: In the present study, the total concentration and bioavailability fraction of copper, lead, zinc, cadmium, nickel, and chromium were measured at 14 coastal stations of Hormozgan province and Qeshm island. Nitric acid and perchloric acid were used to measuring the total concentration and K protease enzyme solution was used to measuring the bioavailable fraction. 
Findings: Zinc and chromium have the highest mean of total concentration, respectively. Qeshm island has more pollution than Hormozgan. The higher bioavailability and higher percentage of components were observed in lead and chromium than the other elements. With increasing concentrations of lead, chromium, and copper, the bioavailability of these elements also increased. As well as, zinc and nickel showed the lowest bioavailability. The concentration of copper, lead, and nickel was also higher than the sediments world average and the WHO / US EPA maximum, and the nickel concentration was above the ERM, PEL, and SEL.
Conclusion: Due to the low accuracy of determining the total concentration of metals in sediment toxicity for aquatics and the need to pay attention to bioavailability fraction, the probability of ecological risk of lead and chromium elements is higher than the other elements for aquatics of Persian Gulf. Zinc and nickel, have the lowest risk to the environment despite the high total concentration.
 

Aims: The current study investigated the concentration of Cu, Pb, Zn, Cd, Ni, and Cr in shell and soft tissue of Saccostrea cucullata, water, and sediments of seven stations in Qeshm Island of Persian Gulf.
Materials & Methods: The samples were digested by a combination of nitric acid and perchloric acid and the concentration of elements was measured by atomic absorption spectroscopy.
Findings: The results indicated that the concentrations of Cu and Zn in all samples, Ni in the sediment and Cd in oyster were the highest bio-water accumulation factor were significantly higher than those of bio-sediment accumulation factor. Also, these factors in the soft tissue were higher than in the shell. Furthermore, the macro-concentrators of soft tissue were Cd, Cu, and Zn, while the macro-concentrator of shell was Cd.
Conclusion: The shell can be an appropriate monitoring tool for evaluating Cu and Zn in water and Cu in sediments. Also, the soft tissue can be practical for monitoring Cu and Zn in sediments.