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JAN
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REPORT 14 |
 Dr.
Paty Matrai and her team have been funded by the National
Science Foundation (NSF) to study complex molecular to
global interactions and feedbacks in the marine cycle of a
volatile sulfur compound, dimethylsulfide (DMS). This research
is key because ocean ecosystems are part of a complex geophysical-biogeochemical
web that transforms matter and energy and sets the conditions
for life on the surface of the Earth. Communication and feedback
between different parts of this web are mediated to a significant
degree by the exchange of radiatively important, biogenic
trace gases. One such feedback involves marine plankton, DMS,
and global climate. In this feedback, DMS produced by marine
phytoplankton and the food web enters the atmosphere and is
oxidized there to sulfate particles, which influence cloud
cover and albedo (i.e., the percentage of light reflected
by an object sucha as a cloud) and, consequently, climate.
Large-scale climate change, in turn, affects phytoplankton
abundance and food web processes in the oceans and thereby
closes the feedback loop.
This field effort will provide
a sharp contrast to earlier studies conducted by the investigation
team in the north Atlantic Ocean. The Southern Ocean (i.e.,
ocean surrounding Antarctica) is characterized by high nutrient
concentrations in the presence of rapidly changing light and
ocean layering, conditions that set into motion intense blooms
and strong decoupling between primary production, grazing
and bacterial production. Studies of these contrasting sites
will enable researchers to evaluate how the structure of biogeochemical-geophysical
webs, and the strengths of interactions within, affect the
cycling of DMS.
A long-term objective
for the international team of scientists is to assess how
the air-sea flux of DMS impacts Earth's climate system in
the present day and to predict how it will do so in the future
under different human-caused carbon dioxide (CO2)
and sulfur emission scenarios. |
