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Biogeochemical processes in land-ocean interfaces, surface estuaries, subterranean estuaries and sediment-water interface
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Chloride Dependency of Cu Transformation in the Presence of Natural Organic Matter at Alkaline pH
P-C2-12
Guowei Xing* , School of Civil and Environmental Engineering, The University of New South Wales
Christopher J. Miller, School of Civil and Environmental Engineering, The University of New South Wales
A. Ninh Pham, School of Civil and Environmental Engineering, The University of New South Wales
T. David Waite, School of Civil and Environmental Engineering, The University of New South Wales
Presenter Email: xgw0829@hotmail.com; z3214434@unsw.edu.au |
| In coastal waters, natural organic matter (NOM) and chloride (Cl-) can significantly influence Cu transformations as a result of the effect of these entities on Cu speciation and associated redox interactions. In this study, the impact of chloride and the well-characterized Suwannee River Fulvic Acid (SRFA) on Cu-transformations was investigated. High chloride concentrations lead to highly-reactive Cu(II) complexes (CuClx2-x) but more stable Cu(I) complexes (CuClx1-x) with respect to reaction with all reductants/oxidants in the system. In the absence of O2, SRFA acted like a hydroquinone in the reduction of Cu(II); in the presence of O2 additional reactions mediated by superoxide that consumed the SRFA reductant needed to be considered, as well as complexation of Cu(I) by an oxidized SRFA moiety. The presence of chloride promoted H2O2 generation by maintaining a higher [Cu(I)]ss in a dynamic steady-state in air-saturated conditions with the O2•−-driven Cu(I) oxidation accounting for the generation of H2O2. A conceptual kinetic model was developed which described all the data obtained. The results of this study assist in understanding the transformations of Cu species that are likely to occur under natural water conditions. |
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