Sohn, R. A., et al., 2008. Explosive volcanism on the ultraslowspreading gakkel ridge, arctic ocean. Nature, 453, 1236–1238.
Staudigel, H., and Schmincke, H.-U., 1984. The Pliocene seamount
series of La Palma/Canary Islands. Journal of Geophysical
Research, 89(B13), 11195–11215.
Vergniolle, S., and Jaupart, C., 1990. Dynamics of degassing at
Kilauea Volcano, Hawaii. Journal of Geophysical Research,
95, 2793–2809.
White, J. D. L., and Houghton, B. F., 2006. Primary volcaniclastic
rocks. Geology, 34, 677–680.
White, J. D. L., Smellie, L. L., and Clague, D. A., 2003. Explosive
Subaqueous Volcanism. Washington, DC: American Geophysical Union.
Witham, F., Blundy, J., Kohn, S. C., Lesne, P., Dixon, J., Churakov,
S. V., and Botcharnikov, R., 2012. SolEx: a model for mixed
COHSCl-volatile solubilities and exsolved gas compositions in
basalt. Computational Geosciences, 45, 87–97.
Yoerger, D. R., et al., 2007. Autonomous and remotely operated
vehicle technology for hydrothermal vent discovery, exploration, and sampling. Oceanography, 20, 152–161.
Zimanowski, B., and Büttner, R., 2003. Phreatomagmatic explosions in subaqueous volcanism. In White, J. D. L., Smellie,
J. L., and Clague, D. A. (eds.), Explosive Subaqueous Volcanism.
Washington, DC: AGU, pp. 51–60.
Cross-references
Axial Volcanic Ridges
Intraoceanic Subduction Zone
Intraplate Magmatism
Island Arc Volcanism, Volcanic Arcs
Marginal Seas
Mid-ocean Ridge Magmatism and Volcanism
Ocean Drilling
Ophiolites
Seamounts
Submarine Lava Types
EXPORT PRODUCTION
Gerold Wefer
1
, Gerhard Fischer
1 and Morten Iversen
2
1
MARUM-Center for Marine Environmental Sciences,
University of Bremen, Bremen, Germany
2
Alfred Wegener Institute, Helmholtz Centre for Polar and
Marine Research, Bremerhaven, Germany
Introduction
Export production (EP) is the fraction of organic carbon
formed by primary production in the photic zone
(photosynthesis) that is not degraded before it sinks below
100–150 m. Typically, EP is measured in units of carbon
due to its importance for the ocean’s biological carbon
pump. Under steady-state conditions and on longer timescales (years), EP is assumed to be in proportion to the part
of primary production that is fed by upwelled nitrate
(Eppley and Peterson, 1979), named new production
(Dugdale and Goering, 1967). A fraction of EP is then
transferred to the deeper ocean (below 1,000 m) and only
less than 1 % of the primary produced organic carbon is
finally stored in the sediment. This transfer of organic
matter from surface waters to the deep sea is known as
the biological pump (Neuer et al., 2014). The final sequestration of organic carbon in the sediments, which stores
CO 2 from the upper ocean and atmosphere over longer
timescales (>1,000 years), is controlled by the strength
of the biological pump.
Primary production, export production, and deep
ocean flux
EP generally mirrors surface distribution of phytoplankton standing stock and primary production. Usually, this
fraction is below 25 % but can be higher in coastal upwelling systems and areas with pulsed production such as the
polar environments. Primary production and export production are low in the so-called ocean deserts such as the
great oligotrophic gyres. Often sediment traps are used
to measure flux and flux attenuation in the deeper water
column. Typically, the flux attenuation is described by a
power function with high attenuation at shallow depths
(Suess, 1980).
Aggregation, marine snow, and fecal pellets
Particles of a few mm in size are not able to sink and constitute the sediment. Therefore, the EP (export flux)
mainly consists of larger particles that are formed in the
surface waters by physical and biological processes such
as coagulation and collision (marine snow) and feeding
activity by zooplankton (fecal pellets). Marine snow and
fecal pellets consist of organic matter from living and dead
organisms and of mineral particles produced both biogenic and non-biogenic. The minerals act as ballast for
larger particles and may enhance their settling velocities
(Iversen and Ploug, 2010), which have an important influence on the strength of the biological pump.
Sediment traps
Sediment traps collect sinking particles over time and area
at a certain water depth, mostly around 1,000 m. The collected material is used to estimate vertical fluxes of
organic carbon and other components such as carbonate,
biogenic opal, or minerals (Buesseler et al., 2007). Sediment traps can be anchored to the seafloor and have multiple time-controlled collectors to reveal annual patterns
of particle sedimentation/flux with a temporal resolution
of a few weeks. Alternatively, sediment traps can also drift
freely with the water body. These drifting traps sample
sinking particles in the upper few hundred meters
(export production/flux) over hours to days. Recently,
drifting traps have been equipped with gels to collect
intact marine snow particles or fecal pellets. Often these
particles fall apart when collected with conventional sediment traps.
Bibliography
Buesseler, K. O., Antia, A. N., Chen, M., Fowler, S. W., Gardner,
W. D., Gustaffson, Ö., Harada, K., Michaels, A. F., Rutgers van
der Loeff, M., Sarin, M., Steinberg, D. K., and Trull, T., 2007.
EXPORT PRODUCTION
247
Staudigel, H., and Schmincke, H.-U., 1984. The Pliocene seamount
series of La Palma/Canary Islands. Journal of Geophysical
Research, 89(B13), 11195–11215.
Vergniolle, S., and Jaupart, C., 1990. Dynamics of degassing at
Kilauea Volcano, Hawaii. Journal of Geophysical Research,
95, 2793–2809.
White, J. D. L., and Houghton, B. F., 2006. Primary volcaniclastic
rocks. Geology, 34, 677–680.
White, J. D. L., Smellie, L. L., and Clague, D. A., 2003. Explosive
Subaqueous Volcanism. Washington, DC: American Geophysical Union.
Witham, F., Blundy, J., Kohn, S. C., Lesne, P., Dixon, J., Churakov,
S. V., and Botcharnikov, R., 2012. SolEx: a model for mixed
COHSCl-volatile solubilities and exsolved gas compositions in
basalt. Computational Geosciences, 45, 87–97.
Yoerger, D. R., et al., 2007. Autonomous and remotely operated
vehicle technology for hydrothermal vent discovery, exploration, and sampling. Oceanography, 20, 152–161.
Zimanowski, B., and Büttner, R., 2003. Phreatomagmatic explosions in subaqueous volcanism. In White, J. D. L., Smellie,
J. L., and Clague, D. A. (eds.), Explosive Subaqueous Volcanism.
Washington, DC: AGU, pp. 51–60.
Cross-references
Axial Volcanic Ridges
Intraoceanic Subduction Zone
Intraplate Magmatism
Island Arc Volcanism, Volcanic Arcs
Marginal Seas
Mid-ocean Ridge Magmatism and Volcanism
Ocean Drilling
Ophiolites
Seamounts
Submarine Lava Types
EXPORT PRODUCTION
Gerold Wefer
1
, Gerhard Fischer
1 and Morten Iversen
2
1
MARUM-Center for Marine Environmental Sciences,
University of Bremen, Bremen, Germany
2
Alfred Wegener Institute, Helmholtz Centre for Polar and
Marine Research, Bremerhaven, Germany
Introduction
Export production (EP) is the fraction of organic carbon
formed by primary production in the photic zone
(photosynthesis) that is not degraded before it sinks below
100–150 m. Typically, EP is measured in units of carbon
due to its importance for the ocean’s biological carbon
pump. Under steady-state conditions and on longer timescales (years), EP is assumed to be in proportion to the part
of primary production that is fed by upwelled nitrate
(Eppley and Peterson, 1979), named new production
(Dugdale and Goering, 1967). A fraction of EP is then
transferred to the deeper ocean (below 1,000 m) and only
less than 1 % of the primary produced organic carbon is
finally stored in the sediment. This transfer of organic
matter from surface waters to the deep sea is known as
the biological pump (Neuer et al., 2014). The final sequestration of organic carbon in the sediments, which stores
CO 2 from the upper ocean and atmosphere over longer
timescales (>1,000 years), is controlled by the strength
of the biological pump.
Primary production, export production, and deep
ocean flux
EP generally mirrors surface distribution of phytoplankton standing stock and primary production. Usually, this
fraction is below 25 % but can be higher in coastal upwelling systems and areas with pulsed production such as the
polar environments. Primary production and export production are low in the so-called ocean deserts such as the
great oligotrophic gyres. Often sediment traps are used
to measure flux and flux attenuation in the deeper water
column. Typically, the flux attenuation is described by a
power function with high attenuation at shallow depths
(Suess, 1980).
Aggregation, marine snow, and fecal pellets
Particles of a few mm in size are not able to sink and constitute the sediment. Therefore, the EP (export flux)
mainly consists of larger particles that are formed in the
surface waters by physical and biological processes such
as coagulation and collision (marine snow) and feeding
activity by zooplankton (fecal pellets). Marine snow and
fecal pellets consist of organic matter from living and dead
organisms and of mineral particles produced both biogenic and non-biogenic. The minerals act as ballast for
larger particles and may enhance their settling velocities
(Iversen and Ploug, 2010), which have an important influence on the strength of the biological pump.
Sediment traps
Sediment traps collect sinking particles over time and area
at a certain water depth, mostly around 1,000 m. The collected material is used to estimate vertical fluxes of
organic carbon and other components such as carbonate,
biogenic opal, or minerals (Buesseler et al., 2007). Sediment traps can be anchored to the seafloor and have multiple time-controlled collectors to reveal annual patterns
of particle sedimentation/flux with a temporal resolution
of a few weeks. Alternatively, sediment traps can also drift
freely with the water body. These drifting traps sample
sinking particles in the upper few hundred meters
(export production/flux) over hours to days. Recently,
drifting traps have been equipped with gels to collect
intact marine snow particles or fecal pellets. Often these
particles fall apart when collected with conventional sediment traps.
Bibliography
Buesseler, K. O., Antia, A. N., Chen, M., Fowler, S. W., Gardner,
W. D., Gustaffson, Ö., Harada, K., Michaels, A. F., Rutgers van
der Loeff, M., Sarin, M., Steinberg, D. K., and Trull, T., 2007.
EXPORT PRODUCTION
247