Phosphorus release

The most commonly used physical method for long-term eutrophication control in lakes is that of artificial destratification. This method is well tried and understood and uses either jetted water or compressed air bubbles to break down the lake stratification in the summer months. Algal growth is also affected by an increase in circulation. This is due to the artificial shading effect which results from the algae spending less time near the surface and consequently less time in the light. This technique also reduces the redox-dependent phosphorus release from sediments because the sediment surface remains aerobic. 

Resin-modified glass-ionomers, like their conventional counterparts, are capable of releasing fluoride [224,264,265], and in greater amounts under acid conditions than neutral ones [265], Release rates and release profiles have been shown to be comparable with those from conventional glass-ionomer cements [264,265], Other ions have also been shown to be released by these materials and, as for fluoride, these ions show a greater release under low pH conditions [265], However, the level of phosphorus released has been shown to be much lower from resin-modified glass-ionomers than from conventional ones [263], This suggests that there is little or no possibility of association of fluoride as monofluorophosphate, but rather that almost all of the fluoride is released either as the free fluoride ion or as alumino-fluoride complex ions. 

Frevert, T. 1979. The pe redox concept in natural sediment-water systems its role in controlling phosphorus release from lake sediments. Arch. Hydrobiol. Suppl. 55, 278-297. 

Cotner, J. B., and R. T. Heath. 1990. Iron redox effects on photosensitive phosphorus release from dissolved humic materials. Limnology and Oceanography 35 1175-1181. 

ABLE 2.4 Rate Constants for Indigenous Phosphorus Release from a Thiokol Silt Loam Soil"... 

Scoville W, Springer S, Crawford J. 1989. Response and cleanup efforts associated with the white phosphorus release, Miamisburg, Ohio. Journal of Hazardous Material 21 47-64. 

Caraco, N.F., Cole, J.J., and Likens, GE. (1989) Evidence for sulphate-controlled phosphorus release from sediments of aquatic systems. Nature 341, 316-318. 

Propensity for Phosphorus Release and Charring Determined by Thermal Analysis for PC/ABS Materials, Combustion Efficiency Multiplied by the Effective Heat of Combustion (% hc)r Residue, PHRR, and THE Determined by Cone Calorimeter... 

Tezuka, Y. (1989). The C N P ratio of phytoplankton determines the relative amounts of dissolved inorganic nitrogen and phosphorus released during aerobic decomposition. Hydrobiologia 173, 55-62. 

The difference in carbonate ion concentration between NADW and the rest of the deep ocean is related to the difference in PO4 concentration. NADW has only about half the concentration of PO4 as does, for example, deep water in equatorial Pacific. This is important because, for each mole of phosphorus released during respiration, 120 mol of CO2 are also produced. This excess CO2 reacts with ion to form two HCOJ... 

Bdstrom B. and Petterson K. (1982) Different patterns of phosphorus release from lake sediments in laboratory experiments. Hydrobiologia 92, 415 -429. 

In freshwater ecosystems, the amounts of phosphorus introduced to sediments are estimated to be of the order of 1 Tg P y while the amounts released from sediments annually are estimated to be less than 1 Tg P (Pierrou, 1976). Emery et al. (1955) calculated that the amount of phosphorus deposited in ocean sediments is 13 Tg P y. The amount of phosphorus released from ocean sediments is unknown but is probably relatively small, as the reducing conditions (lack of oxygen) required occur relatively rarely in the ocean. The uptake of phosphorus by phytoplankton in the ocean has been variously calculated as 1300 Tg P y (Emery et al., 1955) and 990 Tg P y (Stumm, 1973). A similar estimate, about 1000 Tg P y, can be made for the amount of phosphorus deposited in oceanic detritus (Pierrou, 1976). 

Phosphorus is usually found in biological systems as the phosphate ion, which transits rapidly through plants and animals, but moves much more slowly through the soil and the oceans, making the phosphorus cycle overall one of the slowest biogeochemical cycles. The major mineral with an important phosphorus content is apatite [Ca5(P04)30H], but this is not a major source, and many organisms rely on soil-derived phosphorus released from dead organic matter for their phosphoms requirements. 

Reaction mixture pH of the reaction mixture Maximal amount of phosphorus released (per cent of total)... 

The most common cause of hyperphosphatemia is a decrease in urinary phosphorus excretion secondary to decreased glomerular filtration rate. ° Retention of phosphorus decreases vitamin D synthesis and induces hypocalcemia, which leads to an increase in PTH. This physiologic response inhibits further tubular reabsorption of phosphorus to correct hyperphosphatemia and normalize serum calcium concentrations. Patients with excessive exogenous phosphorus administration or endogenous intracellular phosphorus release in the setting of acute renal failure may develop profound hyperphosphatemia. Severe hyperphosphatemia is commonly encountered in patients with chronic kidney disease, especially those with GFRs less than 15 mL/ min per 1.73 m (see Chap. 44). 

Any disorder that results in necrosis of skeletal muscle cells (i.e., rhabdomyolysis) can result in the release of large amounts of intracellular phosphorus into the systemic circulation. This condition is frequently associated with acute renal failure and thus severe hyperphosphatemia may develop due to increased endogenous phosphorus release coupled with decreased renal phosphorus excretion. Bowel infarction, malignant hyperthermia, and severe hemolysis are also conditions that may increase endogenous release of phosphorus. 

Fig. 8-12 Changes of phosphorus in a Baltic sediment during a redox turnover from oxidizing toward reducing conditions. The phosphorus has been separated into three different groups where NAI-F denotes non-apatite inorganic phosphorus (see text). The phosphorus released from the sediment comes solely from the organic-P and NAI-P fractions. Reproduced from Holm (1978) with permission.

Hartwig, E. O. (1976). The impact of nitrogen and phosphorus release from a siliceous sediment on the overlying water. In Estuarine Processes (M. L. Wiley, ed.), Vol. I, pp. 103-117. Academic Press, New York. 

BARIUM DIHYDROXIDE (17194-00-2) A strong base. Reacts with phosphorus, releasing phosphine gas. Violent exothermic reaction with maleic anhydride. Reacts violently with acids, chlorinated rubber (when heated), 1-nitropropane, zirconium powder or dust. Incompatible with organic anhydrides, acrylates, alcohols, aldehydes, alkylene oxides, substituted allyls, cresols, caprolactam solution, epichlorohydrin, ethylene dichloride, glycols, isocyanates, ketones, nitrates, nitromethane, phenols, vinyl acetate. Attacks chemically active metals (e.g. aluminum, magnesium, zinc). 

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