Specification of Cu, Pb and Cr in Contaminated Sediment Effected by pHby Chin-Yuan Chen,
Abstract: Sediment was sampled from a contaminated river. Sequential extraction was applied to determine the speciations of Cu, Pb, and Cr in the sediment with varied pH (5–9), and the redox potential was maintained at -150 mV. Pretreatments of sequential extraction with oxidic and anoxic conditions were investigated. Experimental results indicated that the pretreatment of sequential extraction should be carried out under anoxic conditions. Under reduction condition (-150 mV), metals in the binding forms of both exchangeable and bound to carbonates were more sensitive to the variations in pH. Both Cu and Cr in exchangeable and bound to carbonates forms increased with increased pH. Pb in exchangeable form did not exist as the pH varied from 5 to 9; in addition, Pb bound to carbonates increased with increased pH. These three metals had different performances in the form of bound to Fe-Mn oxides. In this form, the amount of Cu was greater in middle pH, Pb was greater in pH value greater than 7.2, and Cr did not alter with pH. All the metals in the forms of bound to sulfidic/organic matter and residual were stable.
Subject Headings: pH | Sediment | Metals (chemical) | Carbonation | Water pollution
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