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past feature
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Earth's Mantle
Exposed
Researchers in Japan have used secondary
ion mass spectrometry to show that
compounds in the Earth's lower mantle can
store up to five times more water than the
world's oceans.
Secondary ion mass spectrometry
measurements show that Earth's
representative lower mantle minerals can
dissolve considerable amounts of hydrogen.
Both magnesium (Mg) and calcium (Ca)
perovskite contain about 0.2-0.4% by
weight of water. The OH absorption bands
in the minerals were also confirmed by the
use of infrared spectroscopy.
The Earth's lower mantle consists of 79%
Mg-perovskite and 5% Ca-perovskite. When
this capacity is integrated over the mass
of the lower mantle, the total mass of
water is about 5 times that of the oceans.
The considerable amounts of hydrogen can
be stored in deep reservoirs such as the
transition zone, lower mantle, and the
Earth's core.
The full article appears in the March 8
issue of Science magazine.
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