Study of biological indicators of heavy metal pollution in sediments and plants of Hoor-Al-Azim wetland

Abstract

Wetland ecosystems are vulnerable to various environmental pollutants. In southwest Iran, the presence of significant wetlands alongside multiple oil facilities has led to serious biological issues for these ecosystems. This study was conducted in 2022 to investigate biological indicators of heavy metal pollution in the sediments and plants of the Hoor-al-Azim wetland. A total of 10 samples of sediments and the plant species Typha latifolia were collected. Heavy metals consist of Pb, Hg, Ni, Cu, and Cd were measured. The contamination level of sediments was assessed using contamination factor (CF) and ecological risk (ER) indices, while the transfer of pollution to native plant species was evaluated through transfer factor (TF) and bioaccumulation factor (BCF) indices. Results indicated that in sediment samples, Cd had the lowest average concentration (0.052 mg/kg) and Ni had the highest (147 mg/kg). In plant samples, Cd also showed the lowest concentration (0.086 mg/kg), while Hg had the highest (43.6 mg/kg). Pb and Ni levels were significantly elevated compared to other metals. The CF and ER indices revealed that Ni and Pb posed the greatest pollution levels and ecological risks. The TF index indicated that lead had the highest biological pollution potential (1.06). The average BCF values for lead, nickel, and copper were 0.05, 0.053, and 0.12, respectively. Overall, sediment pollution levels in the wetlands near oil facilities are concerning. Therefore, implementing environmental management strategies, including bioremediation, is crucial to mitigate pollution impacts.