Heavy Metal Contamination in the Sediments of Anzali International Wetland, Northern Iran Based on Type Regional Development

Background: The most important factors and problems threatening the Anzali Wetland are the contaminant load and sediments entering the wetland, as well as lack of an integrated management plan for this wetland. The main objectives of the current research were to explore whether there are significant differences in concentrations of Zn, Cd, and Pb in surface sediments among different sites (based on type region development) of the Anzali Wetland, Northern Iran. Methods: Through a field study, samples were collected from 10 stations based on the type of regional development and contaminant source inputs of Anzali Wetland in 2015. Using a hot-block digester, the sediment samples were digested with a 4:1 combination of nitric acid (HNO3) and perchloric acid (HCLO4) for one hour at 40 °C, followed by 3 h at 140 °C. Afterwards, samples were filtered with Whatman 42, filter paper and the filtrate was kept in polyethylene containers at 4 °C, until analysis by atomic absorption spectrometry (AAS). Results: Mean ± SD levels of metals in the sediments of different stations were 26.7 ± 3.49 (lead), 4.36 ± 0.47 (cadmium), and 88.44 ± 10.06 (zinc) μg g-1 dw. There was a significant difference between the stations of the wetland (P < 0.05). This difference could be due to the variations in the input of contaminant sources into the Anzali Wetland. Conclusions: The areas, affected by urban and industrial developments, had the highest level of contamination while the agricultural and less-developed areas had the lowest level of contamination, and therefore, protective plans must be implemented in developed areas in order to lower the level of heavy metals.