A new sequential extraction procedure for the speciation of particulate trace elements in river sediments

In order to study the bioavailable fraction of river sediments, an analytical procedure involving sequential chemical extraction (soluble with water, really exchangeable, bound to carbonates, manganese oxides, amorphous iron oxides, crystalline iron oxides and to organic matter) has been developed for the speciation of: Si, Ca, Fe, K, Mn, Al, Co, Rb, Sr, Y, Sb, Cs, Pb, U, Th and the lanthanides. Experimental results obtained on replicate samples of river bottom sediments demonstrate that the relative standard deviation of the sequential extraction procedure is very low. The selectivity, the efficiency and the purity of the various reagents toward specific geochemical phases were evaluated and optimized on each individual extraction.