Phosphorus cycle reservoirs

Fig. 4-8 The global phosphorus cycle. Values shown are in Tmol and Tmol/yr. (Adapted from Lerman et al. (1975) and modified to include atmospheric transfers. The mass of P in each reservoir and rates of exchange are taken from Jahnke (1992), MacKenzie et al. (1993) and Follmi (1996).)...

Table 4-1 Response of phosphorus cycle to mining output. Phosphorus amounts are given in TgP (1 Tg = 10 g). Initial contents and fluxes as in Fig. 4-7 (system at steady state). In addition, a perturbation is introduced by the flux from reservoir 7 (mineable phosphorus) to reservoir 2 (land phosphorus), which is given by 12 exp(0.07t) in units of Tg P/yr...

Unlike other biogeochemical elements, phosphorus does not have a significant atmospheric reservoir. Thus, while some amount of phosphorus is occasionally dissolved in rain, this does not represent an important link in the phosphorus cycle. River runoff is the primary means of transport between the land surface and oceans, and unlike the other elements discussed. 

Fig. 14-7 The global phosphorus cycle. Values shown are Tmol and Tmol/yr for reservoirs and fluxes, respectively. (T = 10 ).

Table 1 Major reservoirs active in the global phosphorus cycle and associated residence times. 

Richey, J. E. (1983). C, N, P, and S cycles Major reservoirs and fluxes the phosphorus cycle. In "The Major Bio-geochemical Cycles and Their Interactions" (B. Bolin and R. B. Cook, eds.), pp. 51-56. John Wiley, New York. 

Fig. 6.11 The benthic phosphorus cycle in deep-sea sediments, a) generalized processes of particulate transport, release and fixation b) example of fluxes of P (in 10 tmol cm M ) between the pore water and the sediment P reservoirs as calculated with a model for a deep-water location at the western European continental platform Goban Spur (after Slomp et al. 1996).

This article begins with a brief overview of the various components of the global phosphorus cycle. Estimates of the mass of important phosphorus reservoirs, transport rates (fluxes) between reservoirs. 

The present model is based on mass balances for three main components representing phytoplankton (A), nutrients (E), and organic phosphorus (C), which can describe phosphorus cycle within a water body as follows. Phytoplankton biomass is produced by the photosynthesis reaction, consuming nutrients (in lakes and reservoirs, the limiting nutrient is phosphorus) and dissolved carbon dioxide, with solar radiation and adequate temperature. Upon death, phytoplankton biomass increases the pool of organic phosphorus, which is in turn converted to phosphate by mineralization bacteria. The model has several kinetic parameters that have to be estimated based on collected data from the specific reservoir under study. 

The land biota reservoir (3) represents the phosphorus contained within all living terrestrial organisms. The dominant contributors are forest ecosystems with aquatic systems contributing only a minor amount. Phosphorus contained in dead and decaying organic materials is not included in this reservoir. It is important to note that although society most directly influences and interacts with the P in lakes and rivers, these reservoirs contain little P relative to soil and land biota and are not included in this representation of the global cycle. 

The continental cycle of phosphorus is determined by ten fluxes (Figure 4.1) closed by a single component Ps indicating the phosphorus supplies on land in soil-vegetation formations and in animals. The supplies of phosphorus in soils are replenished due to fluxes Hf (l = 2,4,5,8,9,10). The loss of phosphorus from the soil is determined by fluxes Hj ( / = 3,6,7,11). As the detailing of surface reservoirs of phosphorus and consideration of more ingenious effects in the interaction between these reservoirs gets more complicated, so the classification of the surface fluxes of... 

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. 

However, phosphorus is not abundant in the biosphere and it often limits microbial growth. The availability of this element is restricted by its tendency to precipitate in the presence of several polyvalent metal ions at neutral to alkaline pH. Large, slowly cycled phosphate reservoirs occur in marine and other aquatic sediments, whereas small, actively cycled reservoirs comprise dissolved phosphate in... 

There are 5 major reservoirs in the Earth system atmosphere, biosphere (vegetation, animals), soils, hydrosphere (oceans, lakes, rivers, groundwater), and the lithosphere (Earth crust). Elemental cycles of carbon, oxygen, nitrogen, sulfur, phosphorus, and other elements interact with the different reservoirs of the Earth system. The carbon cycle has important aspects in tropical forests due to the large amount of carbon stored in the tropical forests and the high rate of tropical deforestation 0acob 1999)-... 

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