to the amount of silica dissolved (enabling characterization of dissolution rates). In addition, the
measurement of natural silicon isotopes in sea water
and in siliceous sediments has been suggested as a
means of assessing the extent of silicate utilization in
surface waters on timescales ranging from years to
millennia. Addition of radioactive
32
Si (half-life 160
y) to incubation solutions recently has been used to
simplify the measurement of silica production rates
in surface ocean waters. In the past,
32 Si has been
difficult to obtain, but recent advances in production
and isolation protocols have made it possible to
produce this radioisotope for oceanographic studies.
Distributions of naturally occurring
32
Si in the water
column and seabed can be used to determine deepocean upwelling rates as well as the intensity of eddy
diffusion (or turbulence) in the deep ocean. This
same radioactive isotope can be used to evaluate
rates of bioturbation (biological particle mixing) in
the seabed on timescales of hundreds of years.
See also
Carbon Cycle.
Further Reading
Craig H, Somayajulu BLK, and Turekian KK (2000)
Paradox lost, silicon-32 and the global ocean silica
cycle. Earth and Planetary Science Letters 175:
297--308.
DeMaster DJ (1981) The supply and removal of silica from
the marine environment. Geochimica et Cosmochimica
Acta 45: 1715--1732.
Dugdale RC, Wilkerson FP, and Minas HJ (1995) The role
of a silicate pump in driving new production. Deep-Sea
Research 42: 697--719.
Gnanadesikan A (1999) A global model of silicon cycling:
sensitivity to eddy parameterization and dissolution.
Global Biogeochemical Cycles 13: 199--220.
Heinze C, Maier-Reimer E, Winguth AME, and Archer D
(1999) A global oceanic sediment model for long-term
climate studies. Global Biogeochemical Cycles 13:
221--250.
Nelson DM, DeMaster DJ, Dunbar RB, and Smith WO Jr
(1996) Cycling of organic carbon and biogenic silica in
the southern Ocean: estimates of water-column and
sedimentary fluxes on the Ross Sea continental shelf.
Journal of Geophysical Research 101: 18519--18532.
Nelson DM, Treguer P, Brzezinski MA, Leynaert A, and
Queguiner B (1995) Production and dissolution of
biogenic silica in the ocean: revised global estimates,
comparison with regional data and relationship to
biogenic sedimentation. Global Biogeochemical Cycles
9: 359--372.
Nozaki Y, Zhang J, and Takeda A (1997)
210
Pb and
210
Po
in the equatorial Pacific and the Bering Sea: the effects
of biological productivity and boundary scavenging.
Deep-Sea Research II 44: 2203--2220.
Ragueneau O, Treguer P, Leynaert A, et al. (2000) A
review of the Si cycle in the modern ocean: recent
progress and missing gaps in the application of biogenic
opal as a paleoproductivity proxy. Global and
Planetary Change 26: 317--365.
Spencer D (1972) GEOSECS II. The 1970 North Atlantic
Station: Hydrographic features, oxygen, and nutrients.
Earth and Planetary Science Letters 16: 91--102.
Treguer P, Nelson DM, Van Bennekom AJ, et al. (1995)
The silica balance in the world ocean: A re-estimate.
Science 268: 375--379.
540 MARINE SILICA CYCLE
measurement of natural silicon isotopes in sea water
and in siliceous sediments has been suggested as a
means of assessing the extent of silicate utilization in
surface waters on timescales ranging from years to
millennia. Addition of radioactive
32
Si (half-life 160
y) to incubation solutions recently has been used to
simplify the measurement of silica production rates
in surface ocean waters. In the past,
32 Si has been
difficult to obtain, but recent advances in production
and isolation protocols have made it possible to
produce this radioisotope for oceanographic studies.
Distributions of naturally occurring
32
Si in the water
column and seabed can be used to determine deepocean upwelling rates as well as the intensity of eddy
diffusion (or turbulence) in the deep ocean. This
same radioactive isotope can be used to evaluate
rates of bioturbation (biological particle mixing) in
the seabed on timescales of hundreds of years.
See also
Carbon Cycle.
Further Reading
Craig H, Somayajulu BLK, and Turekian KK (2000)
Paradox lost, silicon-32 and the global ocean silica
cycle. Earth and Planetary Science Letters 175:
297--308.
DeMaster DJ (1981) The supply and removal of silica from
the marine environment. Geochimica et Cosmochimica
Acta 45: 1715--1732.
Dugdale RC, Wilkerson FP, and Minas HJ (1995) The role
of a silicate pump in driving new production. Deep-Sea
Research 42: 697--719.
Gnanadesikan A (1999) A global model of silicon cycling:
sensitivity to eddy parameterization and dissolution.
Global Biogeochemical Cycles 13: 199--220.
Heinze C, Maier-Reimer E, Winguth AME, and Archer D
(1999) A global oceanic sediment model for long-term
climate studies. Global Biogeochemical Cycles 13:
221--250.
Nelson DM, DeMaster DJ, Dunbar RB, and Smith WO Jr
(1996) Cycling of organic carbon and biogenic silica in
the southern Ocean: estimates of water-column and
sedimentary fluxes on the Ross Sea continental shelf.
Journal of Geophysical Research 101: 18519--18532.
Nelson DM, Treguer P, Brzezinski MA, Leynaert A, and
Queguiner B (1995) Production and dissolution of
biogenic silica in the ocean: revised global estimates,
comparison with regional data and relationship to
biogenic sedimentation. Global Biogeochemical Cycles
9: 359--372.
Nozaki Y, Zhang J, and Takeda A (1997)
210
Pb and
210
Po
in the equatorial Pacific and the Bering Sea: the effects
of biological productivity and boundary scavenging.
Deep-Sea Research II 44: 2203--2220.
Ragueneau O, Treguer P, Leynaert A, et al. (2000) A
review of the Si cycle in the modern ocean: recent
progress and missing gaps in the application of biogenic
opal as a paleoproductivity proxy. Global and
Planetary Change 26: 317--365.
Spencer D (1972) GEOSECS II. The 1970 North Atlantic
Station: Hydrographic features, oxygen, and nutrients.
Earth and Planetary Science Letters 16: 91--102.
Treguer P, Nelson DM, Van Bennekom AJ, et al. (1995)
The silica balance in the world ocean: A re-estimate.
Science 268: 375--379.
540 MARINE SILICA CYCLE