John Wiley & Sons, Ltd.

Copper and nickel partitioning with nanoscale goethite under variable aquatic conditions

Metal contaminated sediments can be toxic to aquatic organisms and are common in human‐dominated ecosystems, which results in metals being a leading cause of ecosystem impairment. Bioavailability of metals is influenced by their affinity for dissolved and solid‐phase ligands, including iron (Fe) oxyhydroxides that have been hypothesized to reduce metal toxicity in sediments. We examined the adsorption kinetics of copper (Cu) and nickel (Ni) with goethite (α‐FeOOH) and characterized the influences of solute metal concentration, pH, ionic strength, and humate concentration on steady‐state partitioning of the metals with goethite under conditions representative of natural aquatic environments. Copper and Ni readily adsorbed to goethite and steady‐state partitioning was achieved within 2 h. While ionic strength had no effect on metal partitioning, adsorption of Cu and Ni to goethite was enhanced by alkaline pH and reduced by competition with humate. Because KD values for Cu and Ni from our study are comparable to values measured in natural systems, we hypothesize that goethite may contribute significantly to the adsorption of both Ni and Cu to particles in the environment. We suggest that incorporating binding by Fe oxides in metal bioavailability models should be a priority for improving risk assessment of metal‐contaminated oxic sediments. This article is protected by copyright. All rights reserved

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