Residence times phosphorus

The negative reciprocal of phosphorus residence time in each reservoir is found on the diagonal entries of matrix A (Table 7.3). A is factored giving six eigenvalues and six characteristic times of the system as the negative reciprocal of the eigenvalues... 

Residence Times. Phosphorus residence times with respect to major depositional processes (see Tables II and IV) are summarized in Table VI. In comparison, the total-P residence time based on external loading is about 4.5 years. Residence times were calculated for a mean water-column depth of 85 m, and steady state was assumed. Although transport of P to the sediment surface by the combination of diatoms, calcite, and terrigenous material is relatively rapid, the low burial efficiency results in a relatively long residence time for total P (about 5 years). In comparison, the residence time for Pb is about 0.6 years (20). Thus, the response time for P changes with respect to loading should be on the order of 5-15 years. 

Table VI. Phosphorus Residence Times with Respect to Various Depositional Processes...

Janus, L.L., and Vollenweider, R.A. (1984) Phosphorus residence time in relation to trophic conditions in lakes. Verh. Inti. Verein. Theor. Angew. Limnol. 22, 179-184. 

Fig. 4.45. The phosphorus residence time, the uptake rates of phytoplankton and zooplankton and POC export fluxes at three sampling stations in the ECS. (a) Residence time for TDP, suspended matter, and net-plankton (b) The phosphorus assimilation rates and carbon assimilation fluxes of phytoplankton (c) The phosphorus grazing rates and carbon grazing fluxes of zooplankton (d) POC export fluxes from the upper 35 m (Zhang et al., 2004) (With permission from Elsevier s Copyright Clearance Center)...

From Table 14-5 it is obvious that the residence time of P in the atmosphere is extremely short. This does not represent chemical reaction and removal of P from the atmosphere but rather the rapid removal of most phosphorus-containing particles that enter the atmosphere. 

Ruttenberg, K. C. (1993). Reassessment of the oceanic residence time of phosphorus. Chem. Geol. 107,405-409. 

Table 7.3. Residence time of phosphorus in each reservoir.

The experimental aspects of this study were focussed on two hard-water lakes in Switzerland, namely, the northern basin of Lake Zurich and Lake Sempach. The hydraulic residence time of Lake Zurich is 1.2 years. Most of the particles in the lake are produced directly or indirectly by biological processes within the lake itself (e.g., photosynthesis, CaC03 precipitation). Phosphorus removal has been implemented in recent years at all wastewater treatment plants discharging into the lake at present Lake Zurich can be described as between meso- and eutrophic. Lake Sempach has an average hydraulic residence time of 15.8 years as in Lake Zurich, particles in the lake waters are primarily autochthonous. Phosphorus concentrations have increased substantially and the lake is eutrophic. 

Table 11.2 Summary of phosphorus reservoir amounts, total fluxes, and residence time.

The residence time of the water in Lake Erie is 2.7 years. If the input of phosphorus to the lake is halved, how long will it take for the concentration of phosphorus in the lake water to fall by 10% ... 

The nature of the Lewis acid and the residence time in the reactor drastically affect the ratio exo/endo of these terminal unsaturations. AICI3-based initiation leads to about 10% of vinylidenes with respect to total unsaturations, whereas the use of BF3-based catalysts, allowing a shorter contact time between the acid and the polymer and thus limiting isomerization, increases this exo structure to 70% or more [25,29]. The vinylidene double bond is much more reactive than the endo one, and favors considerably the furt her terminal functionalization of the oligomers for example, maleination, epoxidation, ozonolysis, reaction with phosphorus pentasul-fide, etc. (Fig. 2). 

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