The Iron Experiments
Richard Barber's Team Goes to the End of the Earth to See
if Dust Once Played a Role in Climate Change p.3
If the Iron Hypothesis actually
works, Martin quipped, he could not only arrest global warming,
he could begin another ice age with enough boatloads of iron.
Barber, who has been a colleague of Martin’s since they were
in graduate school, served as chief scientist on the first
“IronEx” cruise to the equatorial Pacific after Martin’s untimely
death and has since participated in others.
Barber’s most recent expedition,
in the south polar summer of January and February 2000, was
dubbed the “Southern Ocean Iron Experiment,” abbreviated SOFeX
(Fe is the chemical symbol for iron). About 100 scientists
participated aboard two research ships from the Scripps Institution
of Oceanography, the R/V Roger Revelle and the R/V
Melville, plus the United States Coast Guard research
icebreaker Polar Star.
The Revelle distributed
trace amounts of iron within two separate 15 kilometers patches
of ocean. Drawing on the discoveries of the New Zealand research
team, one patch was located in the ocean’s southern half,
which is richer in silicon. The other patch was laid out in
the silicon-poorer northern half. All three research vessels
then monitored the two patches to assess what would happen
to the iron and how the iron would affect the growth of phytoplankton
and the zooplankton that feed on them.
Injected into both patches were
measured amounts of sulfur hexafluoride, a soluble form of
Teflon®. While chemically inert, sulfur hexafluoride is detectable
at especially tiny concentrations and was used as a tracer
to gauge how quickly the iron spread into the adjoining waters
of each patch.
“At a university like Duke, this
kind of large-team science is not fashionable,” Barber acknowledges.
“What sets Duke apart from a lot of places is the emphasis
on individual accomplishment, and team research doesn’t necessarily
demonstrate that. This is more typical of a government laboratory.”
Nevertheless, Duke was well-represented
on SOFeX, with Barber’s graduate student Michael Hiscock and
technician Anna Hilting working aboard Melville and
Barber's graduate student Veronica Lance and then Duke undergraduate
David Stuebe aboard the Revelle.
Hiscock’s major research task was
to study the “quantum yield” of chrorophyll in the microscopic
marine plants, following in the footsteps of two previous
Duke graduate students who studied the same subject in the
earlier IronEx experiments. Quantum yield is a measure of
plant chlorophyll’s efficiency. “Mike has clear and very exciting
evidence that adding iron increases the quantum yield,” Barber
says. “That means there is more carbon fixed for each unit
of sunlight.”
page 1 | 2
| 3 | 4
| 5
|
