Evaluation of Toxicity Potential and Spatial Distribution of Ecological Risk of Heavy Metals in Surface Sediments of Anzali International Wetland Using GIS

Document Type : Original Article


1 Department of Wetlands Ecosystem Management and Planning, Conservation and Rehabilitation of Wetlands Bureau, Department of Environment (DoE), Tehran, Iran

2 Department of Environmental Sciences, Faculty of Sciences, University of Zanjan, Zanjan, Iran


Introduction; Due to the potential toxicity and ecological risk of heavy metals in aquatic ecosystems, measuring and evaluating their concentration in different parts of aquatic environments is very necessary. Therefore, the present study measures the concentrations of Cd, Cr, Pb, Ni, As and Zn and evaluates the spatial distribution of their ecological risk in the surface sediments of Anzali International Wetland.
Materials and methods; 50 stations in different parts of the wetland were selected for sampling. After preparation and acid digestion of samples, the concentrations of these metals were determined by an atomic absorption spectrometer. In order to zoning the toxicity and ecological risk of metals, the inverse distance weighting (IDW) method was used.
Results and discussion; The total mean concentrations of metals were Zn (79.24 71 6.71), Cr (19.4 21 21.04), Ni (18.96 62 5.62), Pb (13.3 72 72.50), As (7.62 96 4.96) and Cd (1.12 ± 3.16) mg/kg, respectively. Investigation of potential acute toxicity, RI, mHQ and PLI indicated low pollution status in wetland sediments. The environmental risk of the metals in the sediments were evaluated as (Cd> As> Pb> Ni> Zn> Cr). In addition, the distribution of toxicity and ecological risk of metals in different parts of the wetland does not follow the same pattern and the western parts of the wetland have more risks.
Conclusion; According to the results, Potential acute toxicity, PLI, mHQ and ecological risk of heavy metals in the sediments of the region are assessed as low and medium. The intense expansion of human activities in the areas around the wetland, along with the deposition and entry of various pollutants in this ecosystem, confirms the need for continuous monitoring of the wetland and assessment of its ecological health risk.


Al-Taani, A.A., Batayneh, A.T., El-Radaideh, N., Ghrefat, H., Zumlot, T., Al-Rawabdeh, A.M., Al-Momani, T. and Taani, A., 2015. Spatial distribution and pollution assessment of trace metals in surface sediments of Ziqlab Reservoir. Jordan. Environmental monitoring and assessment. 187(2), 1-14.
ALabdeh, D., Karbassi, A.R., Omidvar, B. and Sarang, A., 2020. Speciation of metals and metalloids in Anzali wetland, Iran. International Journal of Environmental Science and Technology. 17(3),1411-1424.
Alahabadi, A. and Malvandi, H., 2018. Contamination and ecological risk assessment of heavy metals and metalloids in surface sediments of the Tajan River. Iran. Marine Pollution Bulletin. 133, 741-749.
Ali, M.M., Ali, M.L., Islam, M.S. and Rahman, M.Z., 2016. Preliminary assessment of heavy metals in water and sediment of Karnaphuli River, Bangladesh. Environmental Nanotechnology, Monitoring & Management. 5, .27-35.
Benson, N.U., Adedapo, A.E., Fred-Ahmadu, O.H., Williams, A.B., Udosen, E.D., Ayejuyo, O.O. and Olajire, A.A., 2018. A new method for assessment of sediment-associated contamination risks using multivariate statistical approach. MethodsX. 5, 268-276.
Bowen, H.J.M., 1979. Environmental chemistry of the elements. Academic press.
Ekoa Bessa, A.Z., Ngueutchoua, G., Kwewouo Janpou, A., El-Amier, Y.A., Njike Njome Mbella Nguetnga, O.A., Kankeu Kayou, U.R., Bisse, S.B., Ngo Mapuna, E.C. and Armstrong-Altrin, J.S., 2021. Heavy metal contamination and its ecological risks in the beach sediments along the Atlantic Ocean (Limbe coastal fringes, Cameroon). Earth Systems and Environment. 5(2), 433-444.
Esmaeilzadeh, M., Karbassi, A. and Moattar, F., 2016. Assessment of metal pollution in the Anzali Wetland sediments using chemical partitioning method and pollution indices. Acta Oceanologica Sinica. 35, 28-36.
Galangash, M.M., 2022. Zonation of heavy metal distribution of surface sediments in Anzali wetland Using Geographical Information System (GIS). Iranian Journal of Research in Environmental Health. Winter. 7(4), 323-331. (In Persian with English abstract).
Haghshenas, A., Hatami-manesh, M., Mirzaei, M., Mir Sanjari, M. and Hossein Khezri, P., 2017. Measurement and Evaluation of Ecological Risk of Heavy Metals in Surface Sediments of Pars Special Economic Energy Zone. Iranian South Medical Journal. 20, 448-469.
Hakanson, L., 1980. An ecological risk index for aquatic pollution control. A sedimentological approach. Water research. 14(8), 975-1001.
Huang, L., Rad, S., Xu, L., Gui, L., Song, X., Li, Y., Wu, Z. and Chen, Z., 2020. Heavy metals distribution, sources, and ecological risk assessment in Huixian wetland, South China. Water. 12, 431-344.
Jamshidi-Zanjani, A. and Saeedi, M., 2013. Metal pollution assessment and multivariate analysis in sediment of Anzali international wetland. Environmental Earth Sciences. 70, 1791-1808.
Kükrer, S., 2018. Vertical and horizontal distribution, source identification, ecological and toxic risk assessment of heavy metals in sediments of Lake Aygır, Kars, Turkey. Environmental Forensics. 19(2), 122-133.
Lao, Q., Su, Q., Liu, G., Shen, Y., Chen, F., Lei, X., Qing, S., Wei, C., Zhang, C. and Gao, J., 2019. Spatial distribution of and historical changes in heavy metals in the surface seawater and sediments of the Beibu Gulf, China. Marine pollution bulletin. 146, 427-434.
MacDonald, D.D., Ingersoll, C.G. and Berger, T.A., 2000. Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Archives of environmental contamination and toxicology. 39, 20-31.
Mandour, A., El-Sayed, M.K., El-Gamal, A.A., Khadr, A.M. and Elshazly, A., 2021. Temporal distribution of trace metals pollution load index in the Nile Delta coastal surface sediments. Marine Pollution Bulletin. 167, 112290. https://doi.org/10.1016/j.marpolbul.2021.112290.
Mirzaei, M., Hatamimanesh, M., Haghshenas, A., Moghaddam, S.M., Ozunu, A. and Azadi, H., 2020. Spatial-seasonal variations and ecological risk of heavy metals in Persian Gulf coastal region: case study of Iran. Journal of Environmental Health Science and Engineering. 18, .91-105.
Mortazavi, S. and Saberinasab, F., 2017. Zoning concentration and ecological risk assessment of heavy metals in sediments of Mighan wetland. Iranian journal of Ecohydrology. 4(2),533-545.  (In Persian with English abstract).
Mortazavi, S. and HatamiManesh, M., 2018. Determination of heavy metals pollution load index in sediments and aquatic plant (Nasturtium microphyllum) in Bashar river, Yasuj. Journal of Environmental Health Enginering. 5(2), 157-172.
Nazarpour, A., Ghanavati, N. and Babaenejad, T., 2017. Evaluation of the level of pollution and potential ecological risk of some heavy metals in surface soils in the Ahvaz oil-field. Iranian Journal of Health and Environment. 10, 391- 400.
Pedersen, F., Bjørnestad, E., Andersen, H.V., Kjølholt, J. and Poll, C., 1998. Characterization of sediments from Copenhagen Harbour by use of biotests. Water Science and Technology. 37, 233-240.
Rahman, S.H., Khanam, D., Adyel, T.M., Islam, M.S., Ahsan, M.A. and Akbor, M.A., 2012. Assessment of heavy metal contamination of agricultural soil around Dhaka Export Processing Zone (DEPZ), Bangladesh: implication of seasonal variation and indices. Applied sciences. 2, 584-601.
Suresh, G., Sutharsan, P., Ramasamy, V. and Venkatachalapathy, R., 2012. Assessment of spatial distribution and potential ecological risk of the heavy metals in relation to granulometric contents of Veeranam lake sediments, India. Ecotoxicology and environmental safety. 84, 117-124.
Talukder, R., Rabbi, M.H., Baharim, N.B. and Carnicelli, S., 2022. Source identification and ecological risk assessment of heavy metal pollution in sediments of Setiu wetland, Malaysia. Environmental Forensics. 23,241-254.
Tomlinson, D.L., Wilson, J.G., Harris, C.R. and Jeffrey, D.W., 1980. Problems in the assessment of heavy-metal levels in estuaries and the formation of a pollution index. Helgoländer meeresuntersuchungen. 33, 566-575.
Vatandoost, M., Naghipour, D., Omidi, S. and Ashrafi, S.D., 2018. Survey and mapping of heavy metals in groundwater resources around the region of the Anzali International Wetland; a dataset. Data in Brief, 18,463-469.
Vu, C.T., Lin, C., Shern, C.C., Yeh, G. and Tran, H.T., 2017. Contamination, ecological risk and source apportionment of heavy metals in sediments and water of a contaminated river in Taiwan. Ecological indicators. 82,32-42.
Wang, J., Liu, W., Yang, R., Zhang, L. and Ma, J., 2013. Assessment of the potential ecological risk of heavy metals in reclaimed soils at an opencast coal mine. Disaster Advances. 6 ,366-77.
Xiao, H., Shahab, A., Xi, B., Chang, Q., You, S., Li, J., Sun, X., Huang, H. and Li, X., 2021. Heavy metal pollution, ecological risk, spatial distribution, and source identification in sediments of the Lijiang River, China. Environmental Pollution. 269, 116189.
Yap, C.K., Ismail, A., Tan, S.G. and Omar, H., 2002. Correlations between speciation of Cd, Cu, Pb and Zn in sediment and their concentrations in total soft tissue of green-lipped mussel Perna viridis from the west coast of Peninsular Malaysia. Environment international. 28,117-126.
Yi, Y., Yang, Z. and Zhang, S., 2011. Ecological risk assessment of heavy metals in sediment and human health risk assessment of heavy metals in fishes in the middle and lower reaches of the Yangtze River basin. Environmental pollution. 159(10), 2575-2585.
Zamani-Ahmadmahmoodi, R., Esmaili-Sari, A., Mohammadi, J., Bakhtiari, A.R. and Savabieasfahani, M., 2013. Spatial distribution of cadmium and lead in the sediments of the western Anzali wetlands on the coast of the Caspian Sea (Iran). Marine pollution bulletin. 74, 464-470.
Zhang, G., Bai, J., Zhao, Q., Lu, Q., Jia, J. and Wen, X., 2016. Heavy metals in wetland soils along a wetland-forming chronosequence in the Yellow River Delta of China: levels, sources and toxic risks. Ecological Indicators. 69, 331-339.