Mangrove forests are one of the most productive and richest ecosystems on the earth. In comparison with other wetland areas, they have been used more directly by human. In this study, Petroleum – Based trace metals (Nickel and Vanadium) were measured in roots and Leaves samples of mangrove trees in Nayband Marine Natural Park and Harra Protected Area, in Persian Gulf. In each habitats, two transects randomly were defined, then three sampling points were taken randomly in each ends. We took the samples from the surface sediments, roots and leaves in each points. So, we had 24 sampling points in each habitat. That means 24 measurements of Nickel and Vanadium in sediments, 24 samples in roots and 24 samples in leaves in each habitats (totally 288 samples). In sediment samples, we also analyzed pH, EC, organic materials, and the texture. The results showed that the concentration of Vanadium and Nickel in root sample of Nayband were 8.36 and 6.18, and in Hara were 20.15 and 15.74, respectively. Likewise sediments, the concentration of the heavy metals in mangrove trees were higher in Hara than in Nayband. Also, the concentration of Nickel and Vanadium were higher in the Leaf samples of the Nayband than those in Harra. Our results also showed that the correlation between Nickel and Vanadium in surface sediments, in the root samples, and in the leaf samples was higher (?= 0.01) in Hara but in Nayband there was no correlation between the concentration Nickel and Vanadium. We found the concentration of Nickel and Vanadium in Harar samples higher than those in Nayband. Analysis of the sediments characteristics showed that the amount of clay and silt in the sediments were significantly higher than those in Nayband. Also, the concentration of Nickel and Vanadium in Hara was increasing by increasing of pH and amount of clay, significantly. The concentration of Nickel and Vanadium in root samples of Hara also was increasing as the amount of clay was increasing. Although, we expected the higher concentration of these trace metals in Nayband but we found totally different results. These would be because of different soil texture, different pH and other sediment characteristics. Also, we assume that the slower slope of the coast in Hara as well as weaker currents and shallower where has affected the absorption of these trace metals by mangrove trees. . Key word: Nickel, Vanadium, Mangrove trees ( Avicennia marina ), surface sediment, transferring factor, bioaccumulation, Nayband Marine National Park, Harra Protected Area.
