Spatial and temporal ecological risk assessment of heavy metals in coastal wetlands
Due to the development of industries as the main consequence of ecological degradation, ecosystems have been affected by a heavy load of industrial pollutants. In our research the concentration of heavy metals at four sampling stations were selected to cover all parts of the wetland. For this purpose, ecological risk index (RI), pollution load index (PLI) and land accumulation index (Igeo) were used to investigate the ecological risk of heavy metals in the sediment environment. The highest value of RI occurs in the fourth station, which is 38.73 and the lowest value was in the first station at 21.36 RI. With the exception of less than 150, heavy metal concentrations showed less spatial differentiation. The highest value of the pollution load index was in the fourth station and its value is 59.00. Accordingly, to the analysis, the Igeo index were less than zero, which shows that the studied sediments are in the nonpolluted range. Only at the station 4, the value of this index for chromium is greater than zero and less than 1 (0.03), which shows that the fourth station is in the range of non-contaminated to moderate contamination The average concentration of heavy metals in the sediments environment for the cadmium was on constant trend, but for other trace, there is a decreasing trend from the first to the third station, then reaches the highest value in the fourth station. Accordingly, its values at the end station have a downward slope. Thus, the wetland is moderately polluted, and the side effects at the core area and buffer zone presenting more exposed level of potential ecological risk for vulnerable groups. According to the results of the present study, the research can point out the need for proper environmental management as regards human activities around the wetlands
:Keywords
Wetlands, heavy metals, vegetation, sediment granulation
گروه: مقالات