Contamination, Toxicity and Ecological Risk Assessment of Heavy Metals in Surface Sediments of Coastal Areas of Bushehr Province: A Systematic Review Study

Background: Heavy metals due to their ecological risks and high toxicity to living organisms are considered as one of the most dangerous pollutants. Therefore, the present study was conducted to investigate the level of pollution, toxicity and the ecological risks of heavy metals in the coastal surface sediments of Bushehr province using systematic review. Methods: To conduct this review study, the concentration level of heavy metals in the surface sediments of Bushehr coastal was obtained by searching for published studies during the 9 years (2012-2020) through databases (Springer, Google Scholar, ProQuest, Web of Science, SID, Magiran). Finally, a comprehensive description of heavy metal pollution, toxicity and risks in coastal sediments was investigated using various indicators. Results: As a result of reviewing the extracted studies from the databases, 24 papers were selected. The survey results showed that the order of mean concentration of heavy metals in sediments was as Zn>Ni>Cr>Cu>Pb>Cd, and the amount of metals Pollution load index in different coastal sediments ranged from 0.15 to 1.99. The order of ecological risks for metals was observed as Cd>Pb>Ni>Cu>Cr>Zn, and the potential ecological risks for metals was obtained in the range of 3.76-257.38. In addition, the results of Toxic unit analysis and modified Hazard quotient of metals showed that the degree of toxicity and risk of contamination varies from very low to severely contaminated. Conclusion: Based on the findings from the perspective of toxicity control and ecological risks of metals, it is necessary to prevent the transfer of heavy metals, especially Cd, Pb and Ni due to dominant human activities in the coastal areas of Bushehr. Also, due to the maximum pollution load and ecological risks in Bidkhon (Assaluyeh) coasts, pollution sources should be determined to effectively control and manage the entry of pollutants in this area.