Determination natural and anthropogenic sources of Cu, Zn, Pb, Cd in the Iranian Coast of Caspian Sea surface sediments using sequential extraction Technique

Coastal sediments as sensitive indicators are employed for monitoring pollution in the coastal areas. Heavy metals in surface sediments originate from natural and/or man-made sources. This study was conducted to determine natural and anthropogenic sources of some heavy metals (Zn, Cu, Cd, Pb) of surface sediment in the southern Caspian Sea during four seasons in 2013-2014. 72 surface sediment samples (with triplicate) were collected at two transects (Tinekabon and Amirabad) and tree depths (5, 10, 20 m) using Van Veen Grab sampler. The heavy metals concentrations of different extraction were measured using atomic absorption spectrometry (AAS) with flame and furnace. Results showed that maximum and minimum concentrations of copper, zinc, lead, and cadmium in the non-resistance part were 0.58-19.31, 0.83-4.21, 4.21-7.86, and 0.31-0.68 and in the resistance part were 4.70-23.33, 4.88-79.19, 7.06-14.84, and 0.23-0.46 µg/g.dw, respectively. In a conclusion, percentage of Cd in the non-resistance part was 58.58% that it contained maximum level among various heavy metals which represents a greater distribution in the anthropogenic origin. While Cu (32.14%), Zn (4.28%) and Pb (35.77%) have natural origin.