FRACTIONATION OF HEAVY-METALS IN SEDIMENT CORES FROM THE ELL-REN RIVER, TAIWAN

Fractionation of heavy metals (Cr, Cu, Co, Zn, Ni, and Pb) in sediment cores taken from three heavily polluted locations of the Ell-Ren Rive r in southern Taiwan was studied. After the three sediment cores were separated into several depth sections, sequential extraction procedure was used to determine the variations in heavy metal binding fractions (exchangeable, bound to carbonates, bound to Mn oxides, bound to Fe o xides, and bound to organic matter) with different sediment depth, and followed by multivariate analyses. It turns out that a deeper sedimen t depth tended to result in smaller amounts of total extractable heavy metals (TEHMs), indicating that heavy metal pollution of the river ha s been intensifying these years. The decreasing order of TEHMs was: Zn > Cu > Pb > Cr > Ni > Co. The TEHMs Zn and Cu detected from different depth of the three sediment cores were mainly originated from ''bound to carbonates'' and ''bound to organic matter'' fractions, respective ly. Also, the percentages of the heavy metals contained in each of the five binding fractons only slightly varied with sediment depth. From multivariate analyses, all the heavy metals except Co behaved similarl y and might be discharged from the same pollution sources. (C) 1998 IA WQ. Published by Elsevier Science Ltd.