Assessment of Sediment-Associated Contamination Risks UsingNew Multivariate Statistical Indexes

This paper presents the assimilation of heavy metal concentration data from sequential extraction method (SEM) with metal toxicity factors to develop and propose a new sediment quality index called ecological contamination index (ECI), to predict the potential ecological risk associated with sediment contamination. Chemical speciation sediment data of five heavy metals: cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), and lead (Pb) from five coastal aquatic ecosystems of the Equatorial Atlantic Ocean were used in assessment of the degree of heavy metal contamination. Other contamination indicators (degree of contamination, modified degree of contamination) used in characterization and identification of pollution hotspots, indicate considerably contaminated ecological ecosystems. Evaluation based on ECI indicates that sediments of most aquatic ecosystems were considerably to highly contaminated. The results illustrate that the proposed index is reliable, precise, and in good agreement with similar existing indexes for evaluating the severity of sediment-associated contamination by heavy metals. The principal component analysis (PCA) and factor analysis indicate that heavy metals in the benthic sediments originate mostly from anthropogenic sources.