Bioavailability and bioaccumulation of heavy metals in the sediment-plant system of Shadegan Wetland, Khuzestan Province

Shadegan Wetland is one of the most important and valuable aquatic habitats in the country that has great importance in terms of biological and ecological in the region's Wildlife. In order to evaluate plant species as an indicator organism of heavy metal pollution in biomonitoring studies of the aquatic ecosystem, the levels of heavy metal accumulation (Mo, Cu, Pb, Zn, As, Se, Hg, Ni, Co, Cd, Cr, V, Mn, Al and Fe) in shoot and root of the macrophytes Typha latifolia, Halocnemum strobilaceum, Aeluropus lagopoides, Phragmites australis and Scripus maritimus was determined. All five species exhibited significantly higher concentrations of metals in roots than in aboveground organs. These species are therefore suitable for use as indicators of the presence and level of heavy metal contaminants in wetlands. Selenium was the most mobile element through the plant tissues with an average bioaccumulation factor exceeds 1. Selenium concentration in the plants was more than levels detected in sediments. Translocation factor values for Phragmites australis were all below 1, suggest-ing low-efficiency plants for metal translocation from roots to shoots. Sequential extractions of sediment samples indicated that three elements including Pb, Ni, and Zn had the most bioavailability.