Occurrence, origin and health risk of arsenic and potentially toxic elements (PTEs) in sediments and fish tissues from the geothermal area of the Khiav River, Ardebil Province (NW Iran)

In this study contamination, ecological and health risk of potentially toxic elements (As, Cr, Cu, Ni, Pb and Zn) were investigated in 22 surface sediments, 3 water and 8 fish (muscle and liver tissues) samples of the Khiav River. Results showed that mean concentration of As, Cr, Cu, Ni and Zn in sediments, and As in water samples are higher than local background and standard values. Moderate to significant enrichment of As in river and very high enrichment in sediments of pollution hotspots were observed, while Zn, Cr, Cu, Ni and Pb showed low to moderate enrichment. Based on mean probable effect level (PEL) quotient, river and hotspot sediments were classified as slightly toxic and heavily toxic, respectively. Potential ecological risk index (PER) indicated low risk and high risk for river sediments and pollution hotspots, respectively. Based on factor analysis, Moiel iron mine and geothermal/hot springs are the main sources of Cr, Zn, Pb and As. Limonite as a secondary mineral accumulated As from hydrothermal or geothermal sources. Concentrations of As, Cr and Pb in fish muscle samples are higher than liver, while higher Cu, Ni and Zn concentrations observed in liver of fish samples. The Mann-Whitney U test revealed significant differences in As, Cu and Zn concentrations between different organs. The average target hazard quotient (THQ) in fish muscle followed the order of As > Cr > Cu > Pb > Zn > Ni, and hazard index (HI) values indicate an alarm for public health concern. Consumption of these fish can cause carcinogenic and non-carcinogenic effects for local people and consumers in long term.