Long-term phosphate

Figure 7.10 The long-term phosphate system (Lasaga, 1980). The arrows show the fluxes that are taken into account.

Figure 7.11 The long-term phosphate system. Evolution of the amount of phosphorus (in units of 109kg) held by the six systems described in Figure 7.10.

Freese, D. Lookman, R. Merckx, R. van Riemsdijk,W.H. (1995) New method for assessment of long-term phosphate desorption from soils. Soil Sci. Soc. Am. J. 59 1295-1300... 

Nehring, D., Schulz, S., Kaiser, W., 1984. Long-term phosphate and nitrate trends in the Baltic proper and some biological consequences A contribution to the discussion concerning the eutrophication... 

A detailed overview of the nutrient situation in the Baltic Sea is given. Hereby, at first recent nutrient inputs are described and compared with the situation before remarkable eutrophication effects were observed. This is followed by a characterization of the typical nutrient cycle in the surface layer as well as by the description of long term phosphate and nitrate trends covering the period from the end of the 1950s until 2005. 

Product Utilization. Zinc phosphate coatings form the basis for paint adhesion in a variety of industries. These are used when long-term quahty is of concern in appHcations such as for automotive parts and vehicles, cod-coated products, and appHances. 

Air-poUutant effects on neural and sensory functions in humans vary widely. Odorous pollutants cause only minor annoyance yet, if persistent, they can lead to irritation, emotional upset, anorexia, and mental depression. Carbon monoxide can cause death secondary to the depression of the respiratory centers of the central nervous system. Short of death, repeated and prolonged exposure to carbon monoxide can alter sensory protection, temporal perception, and higher mental functions. Lipid-soluble aerosols can enter the body and be absorbed in the lipids of the central nervous system. Once there, their effects may persist long after the initial contact has been removed. Examples of agents of long-term chronic effects are organic phosphate pesticides and aerosols carrying the metals lead, mercury, and cadmium. 

The corrosion rig has been used to study the effect of inhibitors e.g. silicate and phosphate commonly used to overcome problems with iron. This has revealed that these inhibitors hardly affect the long-term corrosion rate, indeed in certain circumstances they may actually increase it. They produce their effect by stabilising the corrosion product developed, thereby preventing the water quality deterioration which is the real complaint... 

This input to design refers to the long-term stability of the raw material sources for the plant. It is only of importance where the raw materials can or do contain impurities which can have profound effects on the corrosivity of the process. Just as the design should cater not only for the norm of operation but for the extremes, so it is pertinent to question the assumptions made about raw material purity. Crude oil (where HjS, mercaptan sulphur and napthenic acid contents determine the corrosivity of the distillation process) and phosphate rock (chloride, silica and fluoride determine the corrosivity of phosphoric acid) are very pertinent examples. Thus, crude-oil units intended to process low-sulphur crudes , and therefore designed on a basis of carbon-steel equipment, experience serious corrosion problems when only higher sulphur crudes are economically available and must be processed. 

New guidelines therefore advocate the use of non-acid phosphates plus some caustic to avoid low pH level depressions. Nevertheless, this type of program is likely to achieve a good success rate in the long term under constant load conditions and careful attention to iron oxide transport and control. 

Wilson, Kent Lewis (1970) in a long-term study found that most of the soluble phosphate was eluted from the cement in the first 24 hours. By contrast the rate of elution of zinc remained constant for 160 days, the length of the study. They concluded that long-term erosion took place at the surface of the oxide particles rather than in the matrix. 

The three most important constituents of FYM are nitrogen, phosphate and potash. Additionally, there are the bulky organic parts derived mainly from the straw and the part of the food that has resisted digestion. Granstedt (2002) showed that the majority of the N (about 90%) in farmyard manure served to maintain the soil humus store and the long term capacity to supply nutrients. 

Monsanto. 1979. Summaries of mutagenicity studies, neurotoxicity studies, teratology studies, long term feeding studies, and 90-day inhalation studies on aryl phosphate ester products. 

Siegel J, Rudolph HS, Getzkin AJ, et al. 1965. Effects on experimental animals of long-term continuous inhalation of a triaryl phosphate hydraulic fluid. Toxicol Appl Pharmacol 7 543-549. 

The transfer of trace elements in phosphate rocks to P fertilizers is dependent upon the manufacturing processes. Triple superphosphate fertilizer contains 60-70% of the Cd present in phosphate rocks (Wakefield, 1980). The transfer coefficients may be similar for most other elements and heavy metals even though there are little data on the transfer of other elements from phosphate rocks to P fertilizers. In general, based on some long-term (> 50 years) soil fertility experiments in the U.S., annual Cd rates from the application of phosphate fertilizers are estimated to range from 0.3 to 1.2 g per ha. The addition of Cd to soils as a contaminant from P fertilizers... 

To purify the SATA-modified (strept)avidin use gel filtration on a desalting column or dialyze against 0.1M sodium phosphate, 0.15M NaCl, pH 7.2, containing lOmM EDTA. At this point, the derivative is stable and may be stored under conditions which favor long-term (strept)avidin activity. 

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.

Hi. Because PRs are natural minerals requiring minimum processing they are environmental benign (Schultz 1992) and iv. PRs could be more efficient than soluble fertilizers in terms of recovery of phosphate by plants, even for short term crops in soils where soluble P is readily leached, as in sandy soils (Yeates and Clarke 1993) and possibly for long-term crops also in other soils (Rajan et al. 1994). 

Figure 5. Bio geochemical transformations of phosphorus in forest soils (a) the long-term relative development of different phosphate fractions in soils of the forest ecosystems (b) the relative contents of P fractions in different soil types. Also, the idealized carbon to organic-P rates (C P0) are illustrated (Nihlgard et al., 1994).

---