Assessment of heavy metal pollution in coastal sediments of the western Caspian Sea

The distribution of heavy metals in sediment samples from the western Caspian Sea coast (near industrial region, Sangachal Terminal) was investigated to obtain information about heavy metal pollution. Forty-three surface sediment samples were collected and analyzed for heavy metals (As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn) using an Agilent 7700x inductively coupled plasma - mass spectrometer system. Hg concentrations were detected by cold vapor atomic absorption spectrometry using Varian SpectrAA 220FS + VGA-77 system. The average concentrations of these heavy metals at the same sampling locations followed the order of Fe > Mn > Ba > Zn > Cr > Ni > Cu > As > Pb > Co > Se > Mo > Cd > Hg. Single element pollution index values including geo-accumulation index (I_geo), contamination factor (Cf), and enrichment factor (Ef) were used to evaluate contamination with heavy metals in sediment samples. Three integrated indexes were used for assessing the degree of pollution: degree of contamination (DC), pollution load index (PLI), and ecological risk index (RI).