Feb 18, 2019

Discovery of abundant ferromanganese microparticles in oxic pelagic sediments

- New insights into the global budget of metallic elements -

Overview of the press release

A research group led by Drs. Yuki Morono and Fumio Inagaki at the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) and Dr. Go-Ichiro Uramoto at Kochi University have investigated subseafloor sediments in the ultra-oligotrophic region of the South Pacific Gyre (SPG) (Figure 1). By using high-resolution imaging techniques, they found abundant (108–109 particles/cm3) micrometer-scale ferromanganese mineral particles (Mn-microparticles) in the oxic pelagic clays of the SPG (Figure 2). Major and trace element compositional analyses revealed that iron and manganese were the major components of Mn-microparticles, while they also contained rare-earth elements. From the number of Mn-microparticles per unit volume of sediment and the global distribution of oxic pelagic clays, they estimated the number of Mn-microparticles to be 1.5–8.8 × 1028 particles, which accounted for 1.28–7.62 Tt of manganese. This estimate is at least two orders of magnitude larger than the manganese budget for manganese nodules and manganese crusts on the seafloor. Additionally, they also found that these Mn-microparticles contained 3.3–19.4 Gt of rare-earth elements and that subseafloor Mn-microparticles contribute significantly to the global budget of metallic elements.

This research was published in Nature Communications on February 6, 2019 (JST).


Figure 1. Locations of sampling sites. Sites are plotted on a global map showing regions that may contain dissolved oxygen and aerobic activity through the entire sedimentary sequence. Dark (light) blue indicates regions likely to feature maximum (minimum) dissolved oxygen and aerobic activity.


Figure 2. (Left) Cross-sectional scanning electron microscopy (SEM) images of resin-embedded oxic pelagic clay. Arrows indicate Mn-microparticles (yellow); (right) SEM image of a Mn-microparticle in a density-separated sample.


Professor Yoshio Takahashi of the Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, also participated in this research. 

To read the full press release, please visit the JAMSTEC website.


Publication details

Journal Nature Communications
Title Significant contribution of subseafloor microparticles to the global manganese budget
Authors Go-Ichiro Uramoto1,2, Yuki Morono1,3, Naotaka Tomioka1, Shigeyuki Wakaki1, Ryoichi Nakada1, Rota Wagai4, Kentaro Uesugi5, Akihisa Takeuchi5, Masato Hoshino5, Yoshio Suzuki5,6, Fumito Shiraishi7, Satoshi Mitsunobu8, Hiroki Suga7,12, Yasuo Takeichi9, Yoshio Takahashi10 & Fumio Inagaki1,3,11
Affiliations: 1. Kochi Institute for Core Sample Research, JAMSTEC 2. Center for Advanced Marine Core Research, Kochi University 3. Research and Development Center for Submarine Resources, JAMSTEC 4. Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization 5. Japan Synchrotron Radiation Research Institute 6. Graduate School of Frontier Sciences, The University of Tokyo 7. Department of Earth and Planetary Systems Science, Hiroshima University 8. Department of Environmental Conservation, Graduate School of Agriculture, Ehime University 9. Institute of Materials Structure Science, High Energy Accelerator Research Organization 10. Department of Earth and Planetary Science, The University of Tokyo 11. Research and Development Center for Ocean Drilling Science, JAMSTEC 12. Present address: Department of Earth and Planetary Science, The University of Tokyo
DOI 10.1038/s41467-019-08347-2
Paper link https://www.nature.com/articles/s41467-019-08347-2


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