Understanding marine environments through ferromanganese oxides.

Marine ferromanganese (Fe-Mn) oxides serve as both reactive interfaces and long-term archives for oceanography and environmental changes on the Earth. These oxides are ubiquitous in the ocean and provide reactive mineral surfaces that control elemental abundances and isotope ratios in seawater. Recent synchrotron-based spectroscopy and high-precision isotope analyses have significantly improved the molecular-scale understanding of elemental partitioning and isotope fractionation, which establishes a basis for understanding the relationships between minerals and seawater. Hydrogenetic Fe-Mn crusts, which grow extremely slowly on the seafloor, archive paleoceanographic information over tens of millions of years, including ocean chemistry, water mass structure, and ocean circulation. Furthermore, ancient terrestrial Fe-Mn deposits provide constraints on the oxygenation of Earth's surface as a consequence of interactions among the atmosphere, ocean, lithosphere, and biosphere. Progress in Fe-Mn oxide research will facilitate a deeper understanding of ocean chemistry, and the evolution of marine and Earth systems.