Geochemistry and ecological risk assessment of the coastal Tajan River using sediment quality indices (Southern Caspian Sea, Iran)

The present study aimed to reveal correlations between environmental events and geochemistry variation and ecological risks of the coastal Tajan River. Sediment quality indices (Cf, Cd, Er, and RI) were applied to achieve the research objectives based on the concentration of toxic metals (As, Cd, Cr, Cu, Ni, Pb, Zn). The probably effective level is based on the concentration of As, Cr, and Ni observed. The coastal zone and the urban sector of the river have experienced a moderate ecological risk since 1975, especially during wet seasons (1988-1997) with a mean sedimentation rate of 2 cm/year. A significant correlation (r=0.439-0.633, p-values < 0.0001) between the toxic metal concentration and the Caspian Sea level fluctuation was obtained. The lowest concentration of toxic metals coincided with the high stand water level. Management practices recommend controlling toxic metals (As, Cd, Ni, Cr, Pb) from the sources and dredging of retention pounds along the Tajan River.

Automated summary

This study aimed to investigate correlations between environmental events, geochemistry variations, and ecological risks along the coastal Tajan River, particularly during wet seasons. Analysis of toxic metal concentrations revealed a moderate ecological risk in the coastal and urban areas, with recommendations for controlling sources of toxic metals and dredging. Significant correlations were found between toxic metal concentrations and Caspian Sea level fluctuations.