Scientists Go To Great Depths For Rare-Earth Elements

Deep-sea mud from the Pacific Ocean contains enough lanthanide metals and yttrium to meet the world’s growing demand for these essential elements used in electronic devices and equipment, researchers in Japan report (Nat. Geosci., DOI: 10.1038/ngeo1185). More than 90% of these metals are currently mined in China because of the low cost of extraction and minimal environmental regulations. But China’s own increasing need for the elements has threatened to create a shortage in the rest of the world (C&EN, May 16, page 28). Although previous geological research has shown that oceanic mud contains rare-earth elements, the distribution and concentration of the metals had not been mapped. To that end, Yasuhiro Kato of the University of Tokyo and colleagues took 2,000 ocean sediment core samples from 78 sites in the Pacific Ocean. Using X-ray fluorescence and inductively coupled plasma mass spectrometry they found the sediments were rich in elements such as dysprosium and europium. The team estimates that a single square kilometer in the central North Pacific contains enough rare-earth metals to supply one-fifth of the world’s annual needs and thus “constitutes a highly promising huge resource for these elements.”