Download Extreme Trapping O

Extreme Trapping
O
From left, John Kemp, Rick Krishfield, and Kiyoshi Hatakeyama deploy a time-series sediment trap through a
hole they’ve drilled in the Arctic Ocean ice cover.
36 • FALL/WINTER 1997
(See Oceanus Vol. 37, No. 2 for further
information on the Ice-Ocean Environmental Buoy)
Susumu Honjo
Susumu Honjo
Susumu Honjo
ne of oceanography’s major challenges is collection
respiring carbon dioxide into the atmosphere and in the
of data from extraordinarily difficult environ
long-term (hundreds of millions of years) when, following a
ments. For those who use sediments traps, two
long trip to the deep seafloor, the carbon of their dead
examples of difficult environments are
bodies is absorbed into Earth’s crust
the deepest oceans and the permaby the plate tectonic process.
nently ice-covered Arctic Basin.
The WHOI PARFLUX group has
Since 1986, Yoshi Nozaki
collaborated over the last decade
(University of Tokyo) has deployed
with the Japan Marine Science and
time-series sediment trap moorings
Technology Center (JAMSTEC) to
in the Japan Trench where the
develop Ice-Ocean Environmental
bottom depth exceeds 9 kilometers.
Buoys (IOEBs) for deployment in the
Despite extreme water pressure on
Arctic. The buoys carry sediment
the instruments at the deepest trap
traps to collect descending particles
(8.8 kilometers), Nozaki has
as well as many sensors to detect the
successfully redeployed the mooring
variability of atmosphere, ice, and
many times to collect multi-year
upper ocean layers. A field team led
samples from this enormous depth.
by WHOI Research Associate Rick
The water column at this location,
Krishfield and Kiyoshi Hatakeyama
nearly three times longer than in
of JAMSTEC fly their gear to an ice
most of the deep ocean, provides an
island in the Arctic Ocean by skiexcellent natural laboratory for
equipped cargo plane. They employ
understanding, on an expanded
a steam auger to cut a hole in the ice
scale, the chemical reactions at work
and then lower first the anchor, a
on settling particles. Nozaki’s work
current meter, and the sediment
Yoshi Nozaki of the University of Tokyo poses with one
of the traps he sends nearly nine kilometers deep.
also concerns the broad-scale
trap, which together form the lower
problem of Earth’s carbon cycle: The
portion of the mooring, followed by
Pacific plate oceanic crust at the bottom of the trench is
instruments situated farther up the line, and finally the
destined to be subducted beneath the continental crust of
buoy that plugs the hole in the ice. The sediment trap is
adjacent plates. Thus ocean surface life forms contribute to
programmed to open and close every half month.
the planet’s carbon cycle both in the short-term when
An ice island slowly describes a circle within the
Canadian Basin where the
present IOEB study is concentrated. This experiment allows
scientists to sample settling
particles and make other
measurements throughout a
wide area over a year or longer
without themselves being
present during the harsh
Arctic winter. The first longterm (one-year), highresolution, time-series
samples have arrived at
WHOI, and we expect their
analysis will contribute a great
deal to our knowledge about
how the biological pump
operates under the Arctic ice.
—Susumu Honjo