SORPTIVE BEHAVIOR OF ZN(II) ON A LAKE SEDIMENT BY SEQUENTIAL EXTRACTION-RADIOTRACER TECHNIQUE

A sequential extraction-radiotracer technique was applied to a sedimen t core sample collected From Lake Biwa (Japan) in order to evaluate re lative importance of the fractionated solid components to sorb Zn(II) ions. The core was previously divided into three parts from the surfac e of the sediment; upper (0-6 cm), middle (6-12 cm) and bottom (12-18 cm). The solid residue after each chemical treatment was collected to perform a sorption experiment by using Zn-65 as a tracer. A difference in the amount of Zn(II) sorption was observed among original samples without any chemical treatments at each depth. The amounts were very s mall (10(-5)-10(-4) mol Zn(II) 100 g(-1) of dry sample) in all fractio ns of the sediment. Electrochemical measurements of cadmium and copper ion sorption supported the results from the radiometric sorption expe riment. The effects of several potential factors on zinc sorption were investigated. Ion exchange of zinc with protons on the mineral surfac es was a significant cause of the zinc sorption. (C) 1997 Elsevier Sci ence B.V.