Phosphorus oceanic sources

In all the experiments, the main decomposition products were phosphonates, which are also stable in concentrated solutions of Mg and Ca chlorides. In some experiments, pyrophosphate, and in smaller amounts triphosphate, could also be detected. The authors thus assume that the primeval ocean contained phosphonates as a source of phosphorus for reactions leading to biochemically relevant molecules. Iron meteorites could have delivered sufficient reduced phosphorus (Fe3P) to the primeval Earth, so the question of prebiotic phosphorus chemistry should be looked at in more detail in the future (Pasek and Lauretta, 2005). 

For radiocarbon, the standard ratio s is provided by the preindustrial atmosphere, for which 8 = 0. Cosmic rays interacting with atmospheric nitrogen were the main source of preindustrial radiocarbon. In the steady state, this source drsource is just large enough to generate an atmospheric delta value equal to zero. The source appears in equation 9 for atmospheric radiocarbon. Its value, specified in subroutine SPECS, I adjust to yield a steady-state atmospheric delta value of 0. The source balances the decay of radiocarbon in the atmosphere and in all of the oceanic reservoirs. Because radiocarbon has an overall source and sink—unlike the phosphorus, total carbon, 13C, and alkalinity in this simulation—the steady-state values of radiocarbon do not depend on the initial values. 

Phosphorous occurs in nature in several forms, mostly as phosphates. The most common source is phosphate rock [Caj(PO )j] and a mineral called apatite. Phosphorus is found in all animal bones and teeth and in most living tissue. Phosphorous nodules are found on the ocean floor along with manganese nodules. 

To begin the discussion, we will present briefly a view of the modern carbon cycle, with emphasis on processes, fluxes, reservoirs, and the "CO2 problem". In Chapter 4 we introduced this "problem" here it is developed further. We will then investigate the rock cycle and the sedimentary cycles of those elements most intimately involved with carbon. Weathering processes and source minerals, basalt-seawater reactions, and present-day sinks and oceanic balances of Ca, Mg, and C will be emphasized. The modern cycles of organic carbon, phosphorus, nitrogen, sulfur, and strontium are presented, and in Chapter 10 linked to those of Ca, Mg, and inorganic C. In conclusion in Chapter 10, aspects of the historical geochemistry of the carbon cycle are discussed, and tied to the evolution of Earth s surface environment. 

Like other dissolved organic nutrients, the chemical composition of organic P is relatively unknown. Marine dissolved organic phosphorus (DOP) composition has been mostly identified as particular compound classes such as monophosphate esters, phosphonucleotides, nucleic acids, phospholipids, phosphonates and polyphosphates (Benitez-Nelson, 2000). Kolowith et al. (2001) found that monophosphate esters and phosphonates are major components in the Pacific Ocean, the Atlantic Ocean and the North Sea. ATP (adenosine triphosphate), ubiquitous in aU living cells, has been used as a model DOP compound in radiotracer experiments to obtain information on P sources and fluxes in natural environments (Bjorkman et al., 2000 Karl and Bossard, 1985) and cyanobacterial cultures (Fu et al., 2006). 

According to the latest estimates of Skinner [18], elements potentially recoverable from seawater are sodium, potassium, magnesium, calcium, strontium, chlorine, bromine, boron, and phosphorus because of their practically unlimited presence in the ocean. After improving respective technologies, recovery of the following elements is expected to become profitable as well lithium, rubidium, uranium, vanadium, and molybdenum. Additional profit can be gained since desalinated water will probably be obtained as a by-product. This could be important for countries with a very limited number of freshwater sources (e.g., Israel, Saudi Arabia). 

Figure 16 Comparison of observed (open) and calculated (solid) depletions of phosphorus, tungsten, cobalt, nickel, molybdenum, and rhenium (circles) together with those for gallium, tin, and copper (inverted triangles) (sources Righter and Drake, 1997, 1999, 2000). The calculated depletions utilize the partitioning expressions of Righter and Drake (1999) for conditions of 2,250 ( 300) K (1,973 °C), 27 ( 6) GPa, AIW = — 0.4 ( 0.3) between a hydrous peridotite (NBO/t = 2.65) magma ocean and metallic liquid. The observed depletions are those of McDonough and Sun (1995), but volatility corrected as described by Newsom and Sims (1991), where the correction is made based on comparisons to trends of lithophile volatile element depletions.

The range of riverine suspended particulate matter that may be solubilized once it enters the marine realm (e.g., the so-called reactive-F ) is derived from three sources. Colman and Holland (2000) estimate that 45% may be reactive, based on RSPM-P compositional data from a number of rivers and estimated burial efficiency of this material in marine sediments. Bemer and Rao (1994) and Ruttenberg and Canfield (1994) estimate that 35% and 31% of RSPM-P is released upon entering the ocean, based on comparison of RSPM-P and adjacent deltaic surface sediment phosphorus in the Amazon and Mississippi systems, respectively. Lower estimates have been published (8% Ramirez and Rose (1992) 18% Froelich (1988) 18% Compton et al. (2000). Higher estimates have also been published (69% Howarth et al. (1995). 

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