Evaluating the Ability of Mangrove Plants in the Asalouyeh Region for Heavy Metals Removal

Located in coastal areas, mangrove forests endure harsh conditions of pollution caused by oil pollutants and heavy metals. In this research, the accumulation of heavy metals lead, zinc, nickel, cadmium, and copper in sediments, leaves, and roots of mangrove plants ( Avicennia marina ) in the Asalouyeh area was investigated. Also, translocation factor (TF) and bioconcentration factor (BCF) were assessed to investigate the ability of mangroves to absorb heavy metals from the growth medium. In order to investigate the role of mangrove plants in the accumulation of heavy metals, leaves, roots, and sediments were randomly sampled from different areas in May 2021. The results showed that the average concentration of lead in the sediments of the different studied areas is between 26 and 91, in the roots 5 to 23 and in the leaves 3 to 9 µg/g, the concentration of the zinc is 117 to 212 µg/g, 65 to 191 and 19 to 27 µg/g, the concentration of the nickel 43 to 78 µg/g, 21 to 62 and 15 to 41 µg/g, cadmium concentration 1.5 to 2.5 µg/g, 1.4 to 2.2 µg/g and 0.8 to 1.05 µg/g and copper concentration 116 to 36 µg/g, 36 to 63 µg/g and 6 to 13 µg/g, respectively. Also, a positive and significant correlation was obtained between the concentration of metals in sediments and plant tissues. TF and BCF in mangrove plants for all metals were less than 1, which indicates that mangrove plant cannot hyperaccumulate heavy metals cadmium, copper, lead, nickel, and zinc. However, it can remove heavy metals from polluted sediments.