In freshwater systems, Cu is predominantly complexed with dissolved organic carbon (DOC), yet it remains unclear how the molecular size and molecular structure of DOC influence complexation. Using an assortment of humic standards, with known structural composition, high and low molecular weight (MW) Cu-DOC complexes were isolated by solid-phase extraction and quantified. High MW fractions of DOC were found to have a greater number of binding sites than low MW fractions. The number of binding sites present in high MW DOC was found to be related to structure (aromaticity) and composition (oxygen functional groups). The relative strength of complexation, determined by cation exchange, was found to be dependent on aromaticity. Results demonstrate the importance of aromatic structure in Cu-DOC complexation and suggest mechanisms for the preferential complexation of Cu by select size fractions.

Influence of dissolved organic carbon molecular weight and structure on copper complexation

239th National Meeting (2010)

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