Geoscience Reference
In-Depth Information
Sinking
POC
Sinking
POC
Bed friction
POC flux
2 g C m
-2
a
-1
Respiration
20 g C m
-
2
a
-
1
Phytoplankton and
terrestrial POM
Burial
0.2 g C m
-2
a
-1
Figure 11.6
Schematic of the particulate organic carbon fluxes off the Hebridean shelf edge.
Figure courtesy of George Wolff, University of Liverpool.
terrestrial sources. We can measure the integrated carbon fluxes using traps and
seabed sampling, and we have a good understanding of what physical processes are
most likely responsible for carrying that carbon. The challenge is to develop tech-
niques that allow us to make compatible and co-located measurements of the
biogeochemistry and the physical transport mechanisms if we are to really under-
stand how different processes contribute to carbon export from the shelf.
More studies like SEEP and SES are needed on a representative variety of shelf-
slope systems to provide a basis for models of cross-slope transport from which we
might hope to obtain globally integrated estimates of carbon export. In addition to
the carbon fluxes off the shelf, there is also a need to estimate the reverse flow of
nutrients from the deep ocean on to the shelf. It is widely conjectured that the deep
ocean is the dominant source of nutrients for new production on the shelf (Liu et al.,
2010
), but present estimates of these fluxes, even for well-studied shelf systems, are
uncertain and often depend on the results of numerical models which have not been
validated for the purpose.
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