Contamination of nearshore surficial sediments from the Iranian coast of the Caspian Sea

Concentrations of heavy metals (Al, Cd, Cu, Pb, Ni, Zn) were analyzed from nearshore surficial sediments collected from the alongshore direction of the Iranian coast of the Caspian Sea. The granulometric composition of fourteen samples was determined. Three grain-size fractions (0.355, 0.212 and 0.075 mm) from each sample, plus fourteen bulk samples, were examined for the presence of heavy metals. Laboratory analysis utilized a cold acetic acid extraction procedure, followed by inductively coupled plasma optical emission spectroscopy. Box and Whisker plots demonstrated that metal concentrations were not homogeneously distributed, and there were large spatial variations in the median concentrations of heavy metals at each sample site. The statistical technique of discriminant analysis revealed that the six heavy metals had distinct and statistically significant concentrations at various locations along the coast. Elevated concentration levels reflected metal loadings from anthropogenic sources located in the vicinity of sampled sites.