The relationship between adsorption of heavy metal and organic matter in river sediments

Abstract

Sediment samples of eight sites in two rivers located in northern Taiwan, the Tao-Chen River and the Lau-Che River, were collected to investigate the influences of organic matter on adsorbabilities of heavy metals in dry and wet periods. A batch scale adsorption study was conducted to examine the adsorbabilities of heavy metals of sediments. In the less polluted river (Tao-Chen River), pH, organic matter, cation exchange capacity (CEC), and heavy metals of sediments were independent of the changes of the flow of the river. In contrast, they would be related to those of the more polluted river (Lau-Che River). Metal concentrations and CEC in sediments were positively correlated with organic matter content. On the other hand, there was significantly positive correlation between the adsorbabilities of heavy metals of sediments and organic matter content. The adsorbabilities of sediments to heavy metals increased in the order Zn < Pb < Cu < Cr. The amount of adsorbed Cr in sediments was much greater than that of the other metals, and Zn was adsorbed much less than others.