Evaluation of the ecological risk of heavy metals in the sediments of coastal wetlandsCase study: coastal wetlands of Chabahar Bay, mangrove ecosystem

In this study, the concentration of heavy metals in water and sediments in four stations of Chabahar Lagoon was investigated. Ecological risk index (RI), pollution load index (PLI), and land accumulation index (Igeo) were used to evaluate the ecological risk of heavy metals in the sediment environment. To evaluate the risk of these metals to human health, the hazard index (HI) for two age groups, adults and children  was used. The results showed that the highest value of the ecological risk index occurred in station 4 with a value of 38.73 and the lowest value occurred in station 1 with a value of 21.36. The calculated RI values for all stations were less than 150, indicating that they are in the low-risk range. The highest value of the pollution load index also occurred in station 4 with a value of 0.59, which shows that the sediments of all four stations were not polluted. However, Igeo values were less than zero, which indicates that the studied sediments are in the non-polluted range. Only station 4 had a value greater than zero and less than 1 for chromium, which is in the range of pollution, not polluted to moderate with this metal. Also, risk index values for minors and adults were calculated at each station. The highest value for minors and adults occurred at station 4 with values of 0.89 and 0.59, respectively. Although HI values are less than 1, minors are more exposed to these metals than adults. These results are very worrying for minors who are a vulnerable group in society.