A geochemical and statistical approach for assessing heavy metal pollution in sediments from the southern Caspian coast

The nearshore marine environment of the Caspian sea is a major repository for toxic metals originating from various sources. Since the persistent toxic metals pose serious health risks this research concentrated on investigating the concentrations and spatial distribution of metals in the nearshore sediments along the Iranian coast of the Caspian sea. Fourteen sampling sites were selected along the coast and approximately 400 g of surficial sediments were obtained. Samples were sieved and three grain size fractions from each sample plus fourteen bulk samples were selected for the analysis of metals. Laboratory analysis of the samples utilized the Cold Acetic protocol, followed by Inductively coupled plasma optical emission spectroscopy. The statistical techniques were used to analyze all obtained data. Linear regression analysis demonstrated that grain size of the sediments was not a major factor controlling the concentrations and spatial distributions of heavy metals. Box and Whisker plots emphasized that metal concentrations were not homogeneously distributed. Discriminant analysis was also proved to be useful in identifying geographic areas where heavy metal concentrations occur along the coast.