The relationship between vertical eddy diffusion and buoyancy gradient in the deep sea

Sarmiento, Jorge L.; Feely, Herbert W.; Moore, Willard S.; Bainbridge, A. E.; Broecker, Wallace S.

doi:10.1016/0012-821x(76)90076-5

Cited by 154 publications

(52 citation statements)

References 13 publications

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“…Although crude, this method provides a first-order estimate of the time it would take to oxidize reduced P relative to atmospheric composition. This estimate is an underestimate of oxidative half-life compared with experimental results (73), and the actual half-lives are likely a factor of 10 -100 times longer, when the inefficiency of UV light in the breakup of water and interactions with other solutes are considered.…”

Section: Methodsmentioning

confidence: 83%

Rethinking early Earth phosphorus geochemistry

Pasek

2008

Proc. Natl. Acad. Sci. U.S.A.

236

209

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Phosphorus is a key biologic element, and a prebiotic pathway leading to its incorporation into biomolecules has been difficult to ascertain. Most potentially prebiotic phosphorylation reactions have relied on orthophosphate as the source of phosphorus. It is suggested here that the geochemistry of phosphorus on the early Earth was instead controlled by reduced oxidation state phosphorus compounds such as phosphite (HPO 3 2؊ ), which are more soluble and reactive than orthophosphates. This reduced oxidation state phosphorus originated from extraterrestrial material that fell during the heavy bombardment period or was produced during impacts, and persisted in the mildly reducing atmosphere. This alternate view of early Earth phosphorus geochemistry provides an unexplored route to the formation of pertinent prebiotic phosphorus compounds, suggests a facile reaction pathway to condensed phosphates, and is consistent with the biochemical usage of reduced oxidation state phosphorus compounds in life today. Possible studies are suggested that may detect reduced oxidation state phosphorus compounds in ancient Archean rocks.meteorites ͉ origins of life ͉ phosphonates ͉ prebiotic ͉ redox chemistry P hosphorus (P) is a key biologic element and is the limiting reagent in many ecosystems. Phosphorus is ubiquitous in biochemistry because phosphorylated biomolecules play major roles in replication and information (as RNA and DNA), metabolism (as ATP, NADPH, and other coenzymes), and structure (as phospholipids). Several key properties of P as phosphate make it advantageous to biologic systems, including thermodynamic instability coupled with kinetic stability, charge and coordination state, and a constant oxidation state under typical redox conditions (1). These features are especially critical to the formation of large informational polymers, and hence highly relevant to the origin and development of early life. Phosphorus Geochemistry and CosmochemistryThe major forms of P in life are summarized in Fig. 1. Inorganic P compounds used by life include orthophosphate, pyrophosphate and other condensed phosphates, phosphite, hypophosphite, and phosphine. These inorganic forms are either used by organisms as sources of P for the synthesis of organic-P biomolecules or are possible metabolic by-products of P metabolism (PH 3 ). Additionally, orthophosphate acts as a buffer in many cells, keeping pH constant at Ϸ7. Organic forms of P include compounds with C-O-P linkages and compounds with C-P linkages, and both are formed from inorganic P by using enzymes.Phosphorus is a lithophile element at the redox conditions on the surface of the Earth, and hence orthophosphate is the dominant form of inorganic P on the surface of the Earth today. The concentration of orthophosphate is water-buffered by the solubility of orthophosphate minerals like apatite, Ca 5 (PO 4 ) 3 (OH,F,Cl), on the present-day Earth, and of whitlockite, Ca 9 MgH(PO 4 ) 7 , and brushite, CaHPO 4 ⅐2H 2 O, before the rise of life-mediated apatite deposition (2). Because ...

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Section: Methodsmentioning

confidence: 83%

Rethinking early Earth phosphorus geochemistry

Pasek

2008

Proc. Natl. Acad. Sci. U.S.A.

236

209

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“…The first widespread application was the use of 228 Ra during the GEOSECS (Geochemical Ocean Sections) expeditions as a tracer of vertical mixing in the deep ocean (e.g. Kaufman et al, 1973;Sarmiento et al, 1976;Sarmiento et al, 1982) and across the thermocline (e.g. Moore, 1972;Trier et al, 1972, Kaufman et al, 1973.…”

Section: Introductionmentioning

confidence: 99%

Radium isotopes as tracers of iron sources fueling a Southern Ocean phytoplankton bloom

Charette

Gonneea

Morris

et al. 2007

Deep Sea Research Part II: Topical Studies in Oceanography

103

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Elevated levels of productivity in the wake of Southern Ocean island systems are common despite the fact that they are encircled by high nutrient low chlorophyll (HNLC) waters.In the Crozet Plateau region, it has been hypothesized that iron from island runoff or sediments of the plateau could be fueling the austral summer phytoplankton bloom. Here, we use radium isotopes to quantify the rates of surface ocean iron supply fueling the bloom in the Crozet

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“…Since values of a between 0 and 3 have been identified in measurements in the ocean (Sarmiento et al 1976;Hoffert and Broecker 1978;Gargett and Holloway 1984;Rehmann and Duda 2000), we choose different values from this range in our experiments. Depending on the value of a, this parameterization results in 0:05Â10 À4 m 2 s À1 .…”

Section: Paramterization Of Vertical Mixingmentioning

confidence: 99%

Sensitivity of North Atlantic subpolar gyre and overturning to stratification-dependent mixing: response to global warming

Marzeion¹,

Levermann²,

Mignot³

2009

Clim Dyn

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We use a reduced complexity climate model with a three-dimensional ocean component and realistic topography to investigate the effect of stratificationdependent mixing on the sensitivity of the North Atlantic subpolar gyre (SPG), and the Atlantic meridional overturning circulation (AMOC), to idealized CO 2 increase and peaking scenarios. The vertical diffusivity of the ocean interior is parameterized as j * N -a , where N is the local buoyancy frequency. For all parameter values 0 B a B 3, we find the SPG, and subsequently the AMOC, to weaken in response to increasing CO 2 concentrations. The weakening is significantly stronger for a C a cr & 1.5. Depending on the value of a, two separate model states develop. These states remain different after the CO 2 concentration is stabilized, and in some cases even after the CO 2 concentration has been decreased again to the pre-industrial level. This behaviour is explained by a positive feedback between stratification and mixing anomalies in the Nordic Seas, causing a persistent weakening of the SPG.

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The relationship between vertical eddy diffusion and buoyancy gradient in the deep sea

Cited by 154 publications

References 13 publications

Rethinking early Earth phosphorus geochemistry

Rethinking early Earth phosphorus geochemistry

Radium isotopes as tracers of iron sources fueling a Southern Ocean phytoplankton bloom

Sensitivity of North Atlantic subpolar gyre and overturning to stratification-dependent mixing: response to global warming

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