Comprehensive Scheme for Evaluation of Potentially Toxic Elements (PTEs) Pollution in Surface Sediments of Wetlands, Case Study: Anzali Wetland

Heavy metals are a serious concern in terms of their pollution in aquatic ecosystems because of their persistence, environmental toxicity and bioaccumulation. Evaluating the total concentration and mobility of potentially toxic elements (PTEs) in surficial sediments of Anzali wetland was taken into consideration in this study. Geo-accumulation index, ecological risk index and effects-range-median quotient were calculated to monitor the pollution risks. Additionally, four-step chemical partitioning analysis was performed on samples from eastern parts of the wetland. Index values categorized the whole area within the moderately to non-contaminated class. PTEs Cd > Pb > As > Zn showed remarkable percentages of total concentration in mobile phases (higher bioavailability risks). High values of LOI (loss on ignition) up to 15% and low values of Fe (1.6–2.62%) in sediment samples (higher shares of organics phase compared with Fe–Mn oxides) confirmed the eutrophic conditions. Findings of this research confirm the necessity of including PTEs index analysis and total concentration data accompanied by chemical partitioning results in mid- and long-term decision-making process within the framework of wetlands monitoring plan.