An evaluation of the extraction efficiencies of some common extractants for Fe, Cr, Mn, Ni, Pb and Cu on five grain-size fractionated, tropical marine sediments.

A number of extractants and extraction procedures were evaluated using a variety of tropical marine sediments fractionated on the basis of grain size. Total metal levels obtained by X-ray fluorescence analysis were used in the normalization of levels obtained by these extractants/extraction procedures. A change in extraction efficiency with change in the pH of the extractant used was observed for Fe and Mn irrespective of particle size of the fraction. Iron was extracted uniformly at each leaching level for the <53micro fractions. Manganese had comparable extraction efficiencies with both weak and strong extractants. The extraction efficiencies for Cr were generally low possibly due to an association with the residual phase. The ease with which both Pb and Ni were extracted indicated that they were only loosely bound in the sediments. The extraction efficiencies for Cu varied widely for the fractions of larger particle sizes but fell within narrow ranges for the <53micro fractions.