Human Footprints on Sediment Quality in the Shadegan International Wetland, Northwest of the Persian Gulf

This study focuses on assessing the contamination of surficial sediments in the Shadegan International Wetland, southwest of the Persian Gulf, identifying heavy metal concentrations, evaluating pollution levels using multi-element indices, and determining pollution sources through statistical analyses. Sediment samples were collected from fifteen sites across the wetland and analyzed for the concentrations of six heavy metal(loid)s including Arsenic (As), Chromium (Cr), Copper (Cu), Nickel (Ni), Lead (Pb), and Zinc (Zn). The results revealed moderate to considerable contamination of sediments with heavy metals such as Cr, Ni, Pb, and Zn, with concentrations exceeding local background levels. Multivariate statistical techniques, including Correlation Matrix and Principal Component Analysis, identified common pollution sources, such as municipal wastewater, industrial effluents, and agricultural runoff. Pollution indices, including the Modified Pollution Index (MPI), the Aggregative Toxicity Index (ATI), the Ecological Contamination Index (ECI), the Contamination Severity Index (CSI), the Toxic Risk Index (TRI), and the Total Toxic Units (STU), were employed to assess pollution severity, revealing moderate to heavy pollution levels in certain areas, primarily attributed to anthropogenic activities. The Safe-Heart indicator, a novel visualization tool introduced in this study, provided a comprehensive overview of sediment pollution, highlighting areas of high contamination and underscoring the urgent need for remediation measures to safeguard the wetland ecosystem and aquatic organisms.