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Complexation of copper by aquatic humic substances from different environments

Diane M. McKnight·Gerald L. Feder·E. Michael Thurman·Robert L. Wershaw
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Abstract

The copper-complexing properties of aquatic humic substances isolated from eighteen different environments were characterized by potentiometric titration, using a cupric ion selective electrode. Potentiometric data were analyzed using FITEQL, a computer program for the determination of chemical equilibrium constants from experimental data. All the aquatic humic substances could be modelled as having two types of Cu(II)-binding sites: one with K equal to about 10 6 and a concentration of 1.0 ± 0.4 × 10 −6 M(mg C) −1 and another with K equal to about 10 8 and a concentration of 2.6 ± 1.6 × 10 −7 M(mg C) −1 . A method is described for estimating the Cu(II)-binding sites associated with dissolved humic substances in natural water based on a measurement of dissolved organic carbon, which may be helpful in evaluating chemical processes controlling speciation of Cu and bioavailability of Cu to aquatic organisms.

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Diane M. McKnight, Gerald L. Feder, E. Michael Thurman, Robert L. Wershaw. 1983. Complexation of copper by aquatic humic substances from different environments. https://doi.org/10.1016/s0048-9697(83)80008-4

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