Mercury concentrations in common carp (Cyprinus carpio) tissues, sediment and water from fish farm along the Karoun River in Iran

The Karoun River is major source of water for warm‌water fish culture industry in southwest of Iran. The aim of the present study was to investigate the distribution of mercury in tissues of marketable common carp and in bottom sediments of fish farms in Khouzestan province. This study was carried out on 45 fish farms that are located on the bank of the Karoun River in Khouzestan province, south-west Iran. Concentration of mercury (Hg) was determined using spectrophotometery in three tissues (muscles, liver and gills) of farmed common carp (Cyprinus carpio), water and bottom sediments of fish farms collected from three regions (North, center and south) of the Karoun River, in Khouzestan province, Iran. The concentrations of Hg in muscle tissue (2.71 mg kg-1 dry matter) of fish from the south were significantly higher (p < 0.05) than from the other two sites. In the center and south sampling zones, Hg concentration in muscle was found to be above the maximum tolerable values provided by Food and Drug Administration standards. The Hg concentration of fish farm sediment and water samples were ranged as 0.46 to 0.48 mg kg-1 dry matter and 3.10 to 4.11 μg Hg L-1, respectively. Finally, Hg concentrations at downstream site were higher than upstream site.