Heavy metals are among the pollutants that cause many problems for aquatic organisms and, ultimately, for humans in aquatic ecosystems. Sediments serve as a reservoir for metal pollutants from both natural and anthropogenic sources. Therefore, the purpose of this study is to investigate the concentrations of both resistant and non-resistant forms of the metals Cu, Cd, Pb, and Hg in surface sediments at depths of 10 and 30 meters along eight transects from the fall and winter of 2018 to the spring and summer of 2019 in the southern Caspian Sea. The results showed that the mean concentration (±SE) of Cu, Pb, Cd (mg/kg dw), and Hg (µg/kg dw) in the resistant fraction were (17.08 ± 1.37), (867.80 ± 8.96), (4.82 ± 0.64), and (5.42 ± 0.05), while the non-resistant fractions were (3.09 ± 0.66), (22.80 ± 1.23), (9.70 ± 0.16), and (8.13 ± 0.05), respectively. When comparing the concentrations of non-resistant forms accessible to living organisms with international standards, it was found that the concentrations of Cu and Hg were lower than the standards, while the concentrations of Pb and Cd slightly exceeded the international standards, suggesting a man-made origin for Pb and Cd. The results of measuring heavy metals in sediments indicated that the contribution of anthropogenic sources to the origin of these metals is greater than that from natural and geochemical sources.
Type of Study:
Original Research |
Subject:
Environmental Geology Received: 2024/07/10 | Accepted: 2024/09/10 | Published: 2024/04/29