Environ. Sci. Technol., 30 (12), 3477 -3486 es9601301 S0013-936X(96)00130-7

Copyright © 1996 by the American Chemical Society

Copper Speciation and Binding by Organic Matter in Copper-Contaminated Streamwater

Robert F. Breault and John A. Colman*

U.S. Geological Survey, 28 Lord Road, No. 280, Marlborough, Massachusetts 01752

George R. Aiken and Diane McKnight

U.S. Geological Survey, 3215 Marine Street, Boulder, Colorado 80303

Received: February 13, 1996

Revised July 10, 1996

Accepted July 26, 1996

Abstract:

Fulvic acid binding sites (1.3-70 µM) and EDTA (0.0017-0.18 µM) accounted for organically bound Cu in seven stream samples measured by potentiometric titration. Cu was 84-99% organically bound in filtrates with 200 nM total Cu. Binding of Cu by EDTA was limited by competition from other trace metals. Water hardness was inversely related to properties of dissolved organic carbon (DOC) that enhance fulvic acid binding: DOC concentration, percentage of DOC that is fulvic acid, and binding sites per fulvic acid carbon. Dissolved trace metals, stabilized by organic binding, occurred at increased concentration in soft water as compared to hard water.

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