Use of an ultrafiltration and gamma‐ray irradiation technique for studying the speciation of trace elements in river waters

Abstract The physicochemical forms of 38 elements in several river waters were measured by size fractionation combined with a gamma (7)‐ray irradiation technique and a neutron activation analysis. The 7‐ray irradiation technique was effectively utilized to decompose organic materials in the river waters and made it possible to estimate the physicochemical forms of trace elements. The dissolved species for alkali and alkaline earth elements, Al, V, Mn, Sb and Au were present mainly as simple inorganic ions in the river waters. The dissolved species of Sc, Cr, Co, Ni, Zn, Se, Ho, Tm, Yb, and Lu predominantly existed as soluble organic complexes, even though significant amounts of Cr, Co, Ni, Zn, and Se were also present as simple ions. The dissolved species of Fe, Ag, La, Ce, Sm, and Eu, on the other hand, were chiefly associated with organic colloids.