Abstract
The Anzali international wetland is a valuable habitat to a wide variety of aquatic flora and fauna. This wetland ecosystem is being threatened due to various pollutants particularly the heavy metals discharging from different point and non-point sources. Concentration of various heavy metals (Cr, Pb, Hg, Cu, Zn, Cd, Ag and Ti) was examined in the water body and Azolla filiculoides (an exotic fern in the Anzali wetland). The samples regarding water and A. filiculoides were randomly carried out in three parts of the wetland (eastern, central and western parts) in May 2015. After preparing and digesting the samples, the concentration of the heavy metals was measured using ICP OES method. The obtained results showed that the concentration of Zn in water and A. filiculoides samples was higher than other heavy meals in all parts of the wetland (p < 0.05). Overall, concentration of the heavy metals was significantly higher in the eastern part of the wetland than other two sampling locations (p < 0.05). Also with comparing the concentration of the heavy metals in water and A. filiculoides, it was found that all examined metals (except Cd and Ag) in A. filiculoides had significantly higher concentration than water sample, while Cd and Ag in water and A. filiculoides did not have a significant difference with each other. Based on the results, it can be concluded that A. filiculoides can effectively absorb Cr, Pb, Zn, Hg, Cu, Cd, Ag and Ti so that it might be used as a valuable species for the bioremediation and the removal of heavy metals from the wetland.
Highlights
Wetlands are considered important ecosystems to improve water quality (Zarkami et al.2020)
The present study aims to determine the amount of heavy metals in water sample and the accumulation capacity and potential biomonitoring capability of the heavy metals by A. filiculoides
The comparison of the accumulation of the heavy metals in the samples related to water body and A. filiculoides is shown in Figs. 1, 2 and 3
Summary
Wetlands are considered important ecosystems to improve water quality (Zarkami et al.2020). These valuable ecosystems are facing with various sources of pollutants with the heavy metals (Bonanno and Giudice 2009). Heavy elements are a group of metals and quasi-metals that are toxic and dangerous even in the low level of concentration. Based on this, they are classified as primarily toxic pollutants in terms of pollution level (Modrzewska and Wyszkowski 2014). Though some metals in the environment are of natural origin, the metals those resulting from industrial pollution can be poisonous, even destruct living things and upset the balance of aquatic organisms (Morillo et al 2004). The main source of heavy metals discharging in aquatic environments are various factories and industries whose effluents contain high amounts of the heavy metals (Mishra et al 2010)
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