A study on heavy metal pollution in marine sediments and their removal from dredged material

Abstract

This study concentrates on the removal of the heavy metals from dredged sediments from a polluted marine area. The metals examined were Cr, Cu, Fe, Ni, Pb and Zn. It was found that the sediments were substantially contaminated by several metals including Cr, Fe, Zn and Cu whereas others such as Ni and Pb seem to be present at normal levels. The metal form distribution in the dredged dried sediments found by the application of a sequential extraction partitioning procedure indicated that an important part of the metal content was carried by the reducible and the organic phase. Batch extraction experiments with acid solutions of various concentrations were carried out in order to investigate the heavy metal removal from the contaminated sediments. Extraction results showed that for most metals studied the percentage extracted was satisfactory. Following, the forms of the remaining in the sediments metals were determined using selective sequential extraction analysis and the results indicated that the residual fraction is hardly removed as opposed to the other fractions which are easily removed by the hydrochloric acid extraction and compose 50 percent of the initial amount of metals present.