Ocean phosphate

Bilhons of metric tons of phosphate rock also are present offshore in the oceans, eg, best estimates are that a biUion tons of pellets that may contain about 30% P2 5 present in a Baja California—Mexico deposit alone. Other areas in the world that contain large, unevaluated amounts of phosphate include AustraUa, Alaska, Africa, the Near East, Pern, Colombia, Brazil, the People s RepubHc of China, MongoHa, and the former Soviet Union. 

Other limitations on phytoplankton growth are chemical in nature. Nitrogen, in the form of nitrate, nitrite and ammonium ions, forms a basic building material of a plankton s cells. In some species silicon, as silicate, takes on this role. Phosphorus, in the form of phosphate, is in both cell walls and DNA. Iron, in the form of Fe(III) hydroxyl species, is an important trace element. Extensive areas of the mixed layer of the upper ocean have low nitrate and phosphate levels during... 

Straight-chain detergents don t work in hard water. Phosphates were added to detergents to soften the water, but phosphates are excellent fertilizer for algae in rivers and oceans. The algae blooms deplete the oxygen in the water, which in turn kills fish. Phosphates were replaced with other water softeners such as sodium carbonate and EDTA. 

Over 20% of the world s open ocean surface waters are replete in light and major nutrients (nitrate, phosphate, and silicate), yet chlorophyll and productivity values remain low. These so-called "high-nitrate low-chlorophyll" or HNLC regimes (Chisholm and Morel, 1991) include the sub-arctic North Pacific (Martin and Fitzwater, 1988 Martin et al, 1989 Miller et al, 1991), the equatorial Pacific (Murray et al, 1994 Fitzwater et al, 1996) and the southern Ocean (Martin et al.,... 

Fig. 10-20 Observed depth profiles of (a) phosphate, (b) dissolved inorganic carbon (TC), (c) alkalinity (TA), and (d) oxygen for the Atlantic, the Indian, and the Pacific Oceans as indicated. Data are from GEOSECS stations within 5° of the Equator in each ocean. (Modified from Baes et al. (1985).)...

Perry, M. J. (1976). Phosphate utilization by an oceanic diatom in phosphorus-limited chemostat culture and in the oligotrophic waters of the central North Pacific. Limnol. Oceanogr. 21,88-107. 

Fig. 14-6 Profiles of potential temperature and phosphate at 21 29 N, 122 15 W in the Pacific Ocean and a schematic representation of the oceanic processes controlling the P distribution. The dominant processes shown are (1) upwelling of nutrient-rich waters, (2) biological productivity and the sinking of biogenic particles, (3) regeneration of P by the decomposition of organic matter within the water column and surface sediments, (4) decomposition of particles below the main thermocline, (5) slow exchange between surface and deep waters, and (6) incorporation of P into the bottom sediments.

Longinelli, A., Bartelloni, M. and Cortecci, G. 1976 The isotopic cycle of oceanic phosphate, I. Earth and Planetary Science Letters 32 389-392. 

When cyanoacetylene (5), which is produced when an electric discharge is passed through a mixture of methane and nitrogen, is dissolved in a phosphate buffer a stable enol-phosphate (6) is formed. Pyrophosphate is produced when neutral aqueous solutions of (6) and orthophosphate are heated, and the phosphorylation of UMP has been achieved. However, from a study of the rate of phosphorylation and a consideration of environmental factors, especially the likely phosphate concentration in oceans, it is suggested that (6) is not an important intermediate in prebiotic phosphorylation. The conversion of the 3 -phosphate of 0 2 -cyclocytidine (7) into 2, 3 -cyclic CMP under mild conditions in aqueous solution has... 

By far the most important ores of iron come from Precambrian banded iron formations (BIF), which are essentially chemical sediments of alternating siliceous and iron-rich bands. The most notable occurrences are those at Hamersley in Australia, Lake Superior in USA and Canada, Transvaal in South Africa, and Bihar and Karnataka in India. The important manganese deposits of the world are associated with sedimentary deposits the manganese nodules on the ocean floor are also chemically precipitated from solutions. Phosphorites, the main source of phosphates, are special types of sedimentary deposits formed under marine conditions. Bedded iron sulfide deposits are formed by sulfate reducing bacteria in sedimentary environments. Similarly uranium-vanadium in sandstone-type uranium deposits and stratiform lead and zinc concentrations associated with carbonate rocks owe their origin to syngenetic chemical precipitation. 

Handschuh and Orgel (1973) studied the mineral struvite. It can be precipitated from ocean water in the presence of phosphate if the concentration of NH ions in the water is greater than 0.01 M. If struvite is heated with urea, magnesium pyrophosphate is obtained in a yield of about 20% after 10 days at 338 K if nucleosides are added to the reaction mixture described above, nucleoside diphosphates such as uridine-5 -diphosphate and diuridine-5 -diphosphate are formed in good yields. 

Pyrite is not only one of the key compounds in Wachtershauser s theory, but could also have fulfilled an important function for phosphate chemistry in prebiotic syntheses. A group in Rio de Janeiro studied the conditions for phosphate sorption and desorption under conditions which may have been present in the primeval ocean. In particular, the question arises as to the enrichment of free, soluble inorganic phosphate (Pi), which was probably present in low concentrations similar to those of today (10 7-10 8M) (Miller and Keffe, 1995). Experiments show that acid conditions favour sorption at FeS2, while a weakly alkaline milieu works in an opposite manner. Sorption of Pi can be favoured by various factors, such as hydrophobic coating of pyrite with molecules such as acetate, which could have been formed in the vicinity of hydrothermal systems, or the neutralisation of mineral surface charges by Na+ and K+. 

The National Research Council of Canada has undertaken a project, in collaboration with Bedford Institute of Oceanography of the Canadian Department of Fisheries and Oceans, to address the need for a seawater certified reference material for micronutrients with the initial objective being the preparation of a material with certified values for nitrate, phosphate, and dissolved silica. 

The problem is to calculate the steady-state concentration of dissolved phosphate in the five oceanic reservoirs, assuming that 95 percent of all the phosphate carried into each surface reservoir is consumed by plankton and carried downward in particulate form into the underlying deep reservoir (Figure 3-2). The remaining 5 percent of the incoming phosphate is carried out of the surface reservoir still in solution. Nearly all of the phosphorus carried into the deep sea in particles is restored to dissolved form by consumer organisms. A small fraction—equal to 1 percent of the original flux of dissolved phosphate into the surface reservoir—escapes dissolution and is removed from the ocean into seafloor sediments. This permanent removal of phosphorus is balanced by a flux of dissolved phosphate in river water, with a concentration of 10 3 mole P/m3. 

Fig. 3-3. Evolution of phosphate concentrations in the dilferent oceanic reservoirs. The time step for the initial adjustment is 25 years. For the long-term evolution shown in the insert, a time step of 2500 years was used.

Oxygen 18o/16o 160 = 99.759 170 = 0.037 lsO = 0.204 Water, biomineralized carbonates and phosphates, sedimentary phosphates and carbonates, silicates, organic matter Climate, plant and animal water metabolism, ocean temperature, provenance (marble), chronostratigraphy... 

Mackensen, A., H.W. Hubberten, N. Scheele, and R. Schlitzer. 1996. Decoupling of delta 3C-C02 and phosphate in Recent Weddell Sea deep and bottom water implications for glacial Southern Ocean paleoceanography. Paleoceanography 11(2) 203-215. 

Wu,., W. Sunda, E.A. Boyle, and D.M. Karl. 2000. Phosphate depletion in the Western North Atlantic Ocean. Science 289 759-762. 

Equation 8.4 predicts that aerobic respiration should release dissolved inorganic nitrogen and phosphorus into seawater in the same ratio that is present in plankton, i.e., 16 1. As shown in Figure 8.3, a plot of nitrate versus phosphate for seawater taken from all depths through all the ocean basins has a slope close to 16 1. Why do both plankton and seawater have an N-to-P ratio of 16 1 Does the ratio in seawater determine the ratio in the plankton or vice versa Current thinking is that the N-to-P ratio of seawater reflects a quasi steady state that has been established and stabilized by the collective impacts of several biological processes controlled by marine plankton. 

Plot of nitrate versus phosphate from all depths and from selected WOCE cruises in all ocean basins. Straight line represents the mean oceanic trend in the data, which has a slope of about 16 1. Source-. From Gruber, N. (2004). Carbon-Climate Interactions, NATO ASI Series, p. 102. 

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