Multivariate analyses on heavy metal binding fractions of river sediments in Southern Taiwan

This study depicts the amounts of heavy metals (Cu, Zn, Pb, Cr, Co, and Ni) bound to four geochemical compositions of sediments (carbonates, Mn oxides , Fe oxides, and organic matters), and the correlations between various geo chemical compositions and their heavy-metal complexes. Hundreds of data, ob tained from sediments of five main rivers (located in southern Taiwan), wer e analyzed by using multivariate analysis method. Among the four different geochemical compositions, the total amount of the six heavy metals bound to organic matter is the highest. Zn is easily bound to various geochemical c ompositions, especially carbonates in sediments of the Yenshui river and th e Potzu river (i.e., the heavily heavy-metal polluted sediments); Cr, Pb, a nd Ni are mainly bound to both Fe oxides and organic matter; Cu has high af finity to organic matter. By performing principal component analyses, the d ata points of organic matter and both Pb and Cu associated with organic mat ter cluster together in sediments of the Peikang, the Potzu, and the Yenshu i rivers, which indicates both Pb and Cu might be discharged from the same pollution sources in these rivers. Moreover, correlations between any two b inding fractions of heavy metal associated with Fe oxides in different rive rs are not consistent, which indicates some factors including the binding s ites of Fe oxides, the extent of heavy metal pollution, binding competition s between heavy metals may affect the amounts of heavy metals bound to Fe o xides. Furthermore, it should be noted that the amount of Pb bound to Fe ox ides is highly correlated with the amount of Fe oxides in sediments of the Peikang, the Potzu, and the Yenshui rivers.