Comparative study of three sequential extraction procedures for metals in marine sediments

In the last few decades, several sequential extraction procedures have been developed, making it difficult to compare the results obtained by the different methods. Three extraction techniques (Tessier et al. 1979; Kersten and Forstner 1986; and the Bureau Communautaire de Reference (BCR)) were applied to four marine sediments with different trace metal contents. To be able to compare the results obtained by methods with different numbers of fractions (6 for Kersten and Forstner, 5 for Tessier, and 4 for BCR), the fractions of each method were grouped into four "equivalents" (acid soluble, reducible, oxidable, and residual). The results obtained for Cu, Pb, Zn, Cr, Mn, and Fe partitioning show that the metal distribution obtained with the three procedures is significantly different. The Tessier procedure gives the lowest concentration values in the acid soluble and oxidable fractions for most of the metals studied. On the other hand, this method usually gave the highest values for the residual fraction. Finally, in the reducible fraction, the Kersten and Forstner procedure showed the highest values for Cu, Cr, and Fe, and the Tessier procedure gave the highest values for Zn, Mn, and Pb. (C) 1998 Elsevier Science Ltd.