Deep-sea mud in the Pacific Ocean as a potential resource for rare-earth elements

Journal name:
Nature Geoscience
Volume:
4,
Pages:
535–539
Year published:
DOI:
doi:10.1038/ngeo1185
Received
Accepted
Published online

World demand for rare-earth elements and the metal yttrium—which are crucial for novel electronic equipment and green-energy technologies—is increasing rapidly1, 2, 3. Several types of seafloor sediment harbour high concentrations of these elements4, 5, 6, 7. However, seafloor sediments have not been regarded as a rare-earth element and yttrium resource, because data on the spatial distribution of these deposits are insufficient. Here, we report measurements of the elemental composition of over 2,000 seafloor sediments, sampled at depth intervals of around one metre, at 78 sites that cover a large part of the Pacific Ocean. We show that deep-sea mud contains high concentrations of rare-earth elements and yttrium at numerous sites throughout the eastern South and central North Pacific. We estimate that an area of just one square kilometre, surrounding one of the sampling sites, could provide one-fifth of the current annual world consumption of these elements. Uptake of rare-earth elements and yttrium by mineral phases such as hydrothermal iron-oxyhydroxides and phillipsite seems to be responsible for their high concentration. We show that rare-earth elements and yttrium are readily recovered from the mud by simple acid leaching, and suggest that deep-sea mud constitutes a highly promising huge resource for these elements.

At a glance

Figures

  1. Distribution of average
[Sigma]REY contents for surface sediments (<2[thinsp]m in depth) in the Pacific Ocean.
    Figure 1: Distribution of average ΣREY contents for surface sediments (<2m in depth) in the Pacific Ocean.

    Circles represent DSDP/ODP sites and squares represent the University of Tokyo piston core sites, with colours corresponding to the dominant origin of surface sediments. Open symbols are sites lacking samples from the sediment surface. Contours represent helium-3 anomalies (δ3He) of mid-depth seawater12. REY-rich mud with average ΣREY >400ppm is designated as a potential resource in this study.

  2. Colour-coded depth profiles of
[Sigma]REY contents in cores.
    Figure 2: Colour-coded depth profiles of ΣREY contents in cores.

    a, The northern tropical Pacific Ocean between 0° and 30°N. b, South of the equator. c, North of 30°N. These are simplified profiles limited to shallower than 50 mbsf. Complete and more detailed depth profiles are given in Supplementary Fig. S1.

  3. Detailed depth profiles of
[Sigma]REY contents in representative cores.
    Figure 3: Detailed depth profiles of ΣREY contents in representative cores.

    The pale grey intervals represent no core recovery.

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Author information

Affiliations

  1. Department of Systems Innovation, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

    • Yasuhiro Kato,
    • Koichiro Fujinaga,
    • Yutaro Takaya,
    • Kenichi Kitamura,
    • Junichiro Ohta,
    • Ryuichi Toda &
    • Takuya Nakashima
  2. Precambrian Ecosystem Laboratory (PEL), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima, Yokosuka, Kanagawa 237-0061, Japan

    • Kentaro Nakamura
  3. Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan

    • Hikaru Iwamori

Contributions

Y.K., K.F., K.N. and H.I. designed the study. K.F., Y.T., K.K., J.O., R.T. and T.N. carried out chemical analyses. Y.K., K.N. and H.I. primarily wrote the manuscript with input from all other co-authors.

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The authors declare no competing financial interests.

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