A study of pollution in sediments from anzali wetland with geo-accumulation index and ecological risk assessment

Maryam Panahandeh1, Nabiollah Mansouri1, Nematollah Khorasani2, Abdolreza Karbassi3, Borhan Riazi1

1 Department of Environmental Science, Graduate School of the Environment and Energy, Tehran Science and Research Branch Islamic Azad University, Tehran, Iran
2 Department of Environment, Faculty of Natural Resources, University of Tehran, Karaj, Iran
3 Department of Environment, Graduate Faculty of Environment, University of Tehran, Tehran, Iran


The Anzali Wetland, is located in south west of the Caspian Sea, is one of the most important aquatic ecosystems in Iran. In recent decades much domestic and industrial untreated wastewater has been deposited in the wetland. This study was done to obtain a preliminary assessment of heavy metals contamination in the wetland sediments. Tests were done to determine levels and distribution of the heavy metals Cd, Cr, Cu, Pb, and Zn in surface sediment of the wetland. Results showed that averages of metal concentrations (in g/g) were: Cd: 1.46 0.66; Cr: 6.12 0.27; Cu 18.12 4.11; Pb: 17.97 1.69 and Zn: 78.08 7.08. Contamination status was evaluated on the Geo-accumulation Index for each of these metals and ecological risk assessment was determined accordingly. The Geo-accumulation Index determined that levels of metals were not in the range indicating contamination (except for Cd that showed a level of moderate contamination), and in terms regional variation, levels of contamination were evaluated in the following order: Shyjan > Hendekhale > Siyahkeshim > Abkenar. Ecological risk assessment showed that Cd was the only metal posing a potentially high risk to the environment and contributed 77.5% of the total potential ecological risk in the Anzali Wetland.


contamination; heavy metals; Geo-accumulation Index; potential ecological risk index

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