Cerium Redox Chemistry in Seawater: Evaluation as a Tracer of Oxide Mediated Scavenging Processes

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Cerium is the only rare earth element which exhibits a redox chemistry in the marine water column. Understanding its geochemistry may provide important insights into the role of redox processes in minor element transport. A preliminary investigation of Ce redox chemistry indicates that it exhibits a dynamic redox chemistry, with Ce(III) oxidation on oxide surfaces and photoreduction of Ce(IV) in surface waters being potentially important processes in its preferential removal and remobilization relative to the trivalent rare earths under different conditions. Furthermore, Ce redox chemistry shows a close similarity to that of manganese. Dr.Sholkovitz and Moffett propose to carry out a detailed laboratory and field investigation of the redox chemistry of Ce in seawater, to expand our basic knowledge of its natural water chemistry and identify the processes important in its transport. The data will be used to evaluate the usefulness of Ce anomaly data as a tracer of metal oxide mediated transport and a geochemical analog of manganese.