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 geochemical compositions and their heavy-metal complexes. Hundreds of data, obtained from sediments of five main rivers (located in southern Taiwan), were 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 compositions, especially carbonates in sediments of the Yenshui river and the Potzu river (i.e., the heavily heavy-metal polluted sediments); Cr, Pb, and Ni are mainly bound to both Fe oxides and organic matter; Cu has high affinity to organic matter. By performing principal component analyses, the data points of organic matter and both Pb and Cu associated with organic matter cluster together in sediments ofthe Peikang, the Potzu, and the Yenshui rivers, which indicates both Pb and Cu might be discharged from the same pollution sources in these rivers. Moreover, correlations between any two binding fractions of heavy metal associated with Fe oxides in different rivers are not consistent, which indicates some factors including the binding sites of Fe oxides, the extent of heavy metal pollution, binding competitions between heavy metals may affect the amounts of heavy metals bound to Fe oxides. Furthermore, it should be noted that the amount of Pb bound to Fe oxides is highly correlated with the amount of Fe oxides in sediments of the Peikang, the Potzu, and the Yenshui rivers.

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