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past feature
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In Deep Water
Iron (Fe) is one of
the most abundant elements on Earth and
plays an important role in many biological
functions. In seawater, the isotopic
abundance of iron is effected by climate
changes and these variations have
widespread implications on the well being
of marine life.
Scientists at the University of Oxford
have used inductively-coupled plasma
source mass spectrometry (ICP-MS) to study
the isotopic composition of iron in deep
sea crusts collected from the San Pablo
sea mount in the North Atlantic ocean.
This crust is estimated to grow at a rate
of 1.6 mm every million years.
Iron isotope compositions were measured
relative to a reference standard as a
function of depth. When plotted as a time
series, the isotope fraction shows small
variations between two to six million
years ago, but show much large variations
within the past two million years. This
variation is interpreted to reflect
changes in North Atlantic sea water during
the time in which the crusts grew.
But what has caused the variation in iron
isotope compositions in more recent times
? The close correlation between variations
in the isotopes of lead (Pb), an element
not utilized biologically, suggests that
their is no biologically induced cause.
Further studies are proposed by the
authors to investigate the mechanisms for
this phenomenon.
Read the full article in Science, Vol. 287, 2000-2002
(2000).
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