Showing papers on "Phosphorus published in 1987"

Generalized watershed loading functions for stream flow nutrients

Abstract: Loading functions are proposed as a general model for estimating monthly nitrogen and phosphorus fluxes in stream flow The functions have a simple mathematical structure, describe a wide range of rural and urban nonpoint sources, and couple surface runoff and ground water discharge Rural runoff loads are computed from daily runoff and erosion and monthly sediment yield calculations Urban runoff loads are based on daily nutrient accumulation rates and exponential wash off functions Ground water discharge is determined by lumped parameter unsaturated and saturated zone soil moisture balances Default values for model chemical parameters were estimated from literature values Validation studies over a three-year period for an 850 km2 watershed showed that the loading functions explained at least 90 percent of the observed monthly variation in dissolved and total nitrogen and phosphorus fluxes in stream flow Errors in model predictions of mean monthly fluxes were: dissolved phosphorus - 4 percent; total phosphorus - 2 percent; dissolved nitrogen - 18 percent; and total nitrogen - 28 percent These results were obtained without model calibration

Phosphorus-31 Nmr Spectroscopy in Stereochemical Analysis

Abstract: General Experimental Techniques and Compilation of Chemical Shift Data Empirical Methods for Interpreting Chemical Shifts of Phosphorus Compounds Special Experimental Techniques in Phosphorus NMR Spectroscopy Oriented Phases Theoretical Considerations: Calculations of the Chemical Shift Theoretical Considerations: Spin-Spin Coupling NMR Studies of the Stereochemistry and Fluxionality of Five- and Six-Coordinate Phosphorus Compounds Mechanisms of Reactions of Phosphorus Compounds Conformation and Stereochemistry of Cyclic Compounds Higher Order 31P NMR Spectra of Polyphosphorus Compounds Stereospecificity in 31P-Element Couplings: Proton-Phosphorus Couplings Stereospecificity in 31P-Element Couplings: Phosphorus-Carbon Coupling Stereospecificity in 31P-Element Couplings: One-Bond Couplings to Other Nonmetals and to Metals Stereochemistry of Metal Complexes: Unidentate Phosphorus Ligands Stereochemistry of Metal Complexes: Polydentate Phosphorus Ligands Stereochemistry of Metal Complexes: Phosphido Bridging Ligands Unusual Ligation Modes of Phosphorus Compounds: One- and Two-Coordinate Phosphorus Compounds Unusual Ligation Modes of Phosphorus Compounds: Phosphorus Ylides Unusual Ligation Modes of Phosphorus Compounds: Phospholes Unusual Ligation Modes of Phosphorus Compounds: Phosphoranides Index.

Effect of phosphorus accumulation on acetate metabolism in the biological phosphorus removal process

Abstract: An experimental study was carried out to investigate the metabolic pathway of acetic acid and the relationship between the phosphorus accumulation in the sludge and the metabolism of organic substrates in the anaerobic aerobic biological phosphorus removal process. Two laboratory-scale anaerobic aerobic processes were operated continuously with different phosphorus loadings and batch experiments were conducted with the sludges obtained from the continuous systems. The metabolic pathway of acetate was postulated, in which NADH2 required for PHB synthesis is supplied from the consumption of intracellular carbohydrate through the EMP pathway. The ability of the sludge to uptake acetate anaerobically was limited by the amount of polyphosphate stored in the cell, so long as the phosphorus content of sludge was below 35 mgP/gVSS. From energy balance consideration, the energy required for the accumulation of polyphosphate is found to be very little compared with the total energy produced and the sludge can maintain the yield coefficient at a required level even when a large amount of polyphosphate is accumulated.

Dietary intake of phosphorus modulates the circadian rhythm in serum concentration of phosphorus. Implications for the renal production of 1,25-dihydroxyvitamin D.

Abstract: We recently reported that in healthy men, changes in the production rate (PR) of 1,25-dihydroxyvitamin D [1,25-(OH)2D] accounted for the 80% increase and the 30% decrease in its serum concentration that was induced by restriction and supplementation, respectively, of dietary phosphorus. These changes in PR and serum concentration of 1,25-(OH)2D could be mediated by changes in serum concentrations of phosphorus that occur after the morning fasting period. To examine this hypothesis, we measured serum concentrations of phosphorus in blood drawn at hourly intervals for 24 h in six healthy men in whom dietary phosphorus was initially maintained at 1,500 mg/70 kg body weight per day for 9 d, then restricted to 500 mg/d (coupled with orally administered aluminum hydroxide) for 10 d, and then supplemented to 3,000 mg/d for 10 d. When dietary phosphorus was normal, the serum concentration of phosphorus exhibited the normal circadian rhythm: a rapid decrease in early morning to a nadir at 1100, followed by an increase to plateau at 1600 h and a further increase to an acrophase (peak) at 0030 h. The variation in serum levels of phosphorus can be described as the sum of sinusoidal functions with periodicities of 24 and 12 h. Phosphorus restriction for 10 d induced a 40% reduction in the 24-h mean serum level of phosphorus, abolished the early afternoon rise in its serum level (i.e., the 12-h periodic component of the time series), and delayed the acrophase by 3 h to 0330 h. Phosphorus supplementation for 10 d induced a 14% increase in the 24-h mean serum level of phosphorus but no significant change in its morning fasting level, exaggerated the early afternoon rise in serum phosphorus, and advanced the acrophase by 9 h to 1530 h. The changes in the PR of 1,25-(OH)2D induced by restriction and supplementation of dietary phosphorus varied inversely and significantly with those induced in the 24-h mean serum level of phosphorus (R = -0.88, P less than 0.001). These data demonstrate that in healthy men, dietary phosphorus is an important determinant of the serum concentration of phosphorus throughout most of the day. The data suggest that diet-induced changes in serum levels of phosphorus mediate the changes in PR and serum concentration of 1,25(OH)2D.

The Impact of Soil and Fertilizer Phosphorus on the Environment

Abstract: Publisher Summary This chapter describes the impact of soil and fertilizer phosphorus on the environment. Phosphorus in the form of phosphate (P) is essential for plant growth and its application to agricultural land often improves crop production. Production per unit area is increased with fertilizer P. The increased plant cover that is possible with proper use of fertilizer can reduce soil erosion from the cultivated area. Addition of phosphorus to fish ponds may also increase fish production. Potentially toxic chemical elements may be introduced into the food chain by adding P fertilizer to the soil. Increase in the amounts of soluble and particulate P transported in surface runoff have been measured after the application of fertilizer P. Phosphorus losses in surface runoff may be reduced by incorporating fertilizer material into the surface soil, away from the zone of extraction and detachment, and by using conservation or minimum tillage methods to reduce soil erosion. The detachment and transport of particulate phosphorus is also elaborated.

Boundary-layer and internal diffusion effects on phosphorus fluxes in lake periphyton1

Abstract: Phosphate uptake kinetics of periphyton were evaluated by addition of carrier-free radiophosphate under controlled laminar flow conditions. In most cases, excluding only poorly colonized substrata, tracer fluxes were found to be limited by boundary-layer mass transfer. Tracer flux could be described as a power function of flow velocity and as a negative power function of distance from the leading edge of the communities, as expected from mass transfer calculations. Observed deviations from theoretical functions were interpreted as effects of community patchiness and of internal water flow in the periphyton matrix. Phosphate turnover by periphyton in suspension was within the range of values for lake plankton, when related to biomass. Kinetic calculations based on these turnover measurements indicated that internal recycling of phosphate and recycling from the boundary layer, rather than external uptake, accounted for most phosphate turnover within intact periphyton films. This situation is likely typical under oligotrophic conditions. Boundarylayer thickness was within the range of published estimates from littoral systems. The results indicate that chemical conditions within periphyton communities differ considerably from the immediate surroundings and that boundary-layer development is a key factor affecting the metabolism of periphyton communities.

Increased Phosphorus Uptake by Wheat and Field Beans Inoculated with a Phosphorus-Solubilizing Penicillium bilaji Strain and with Vesicular-Arbuscular Mycorrhizal Fungi

Abstract: Greenhouse and field experiments were conducted to test the effect of a P-solubilizing isolate of Penicillium bilaji on the availability of Idaho rock phosphate (RP) in a calcareous soil. Under controlled greenhouse conditions, inoculation of soils with P. bilaji along with RP at 45 μg of P per g of soil resulted in plant dry matter production and P uptake by wheat (Triticum aestivum) and beans (Phaseolus vulgaris) that were not significantly different from the increases in dry matter production and P uptake caused by the addition of 15 μg of P per g of soil as triple superphosphate. Addition of RP alone had no effect on plant growth. Addition of vesicular-arbuscular mycorrhizal fungi was necessary for maximum effect in the sterilized soil in the greenhouse experiment. Under field conditions, a treatment consisting of RP (20 kg of P per ha of soil) plus P. bilaji plus straw resulted in wheat yields and P uptake equivalent to increases due to the addition of monoammonium phosphate added at an equivalent rate of P. RP added alone had no effect on wheat growth or P uptake. The results indicate that a biological system of RP solubilization can be used to increase the availability of RP added to calcareous soils.

Effects of vesicular-arbuscular mycorrhiza on the availability of iron phosphates to plants

Abstract: The effect of inoculation with a mycorrhizal fungus on the growth of subterranean clover and of ryegrass was measured using three sources of phosphorus with different solubilities. These were (in order of decreasing solubility): potassium dihydrogen phosphate, colloidal iron phosphate and crystalline iron phosphate. Mycorrhizal infection increased growth more for subterranean clover than for ryegrass for all sources of phosphorus. For both species the greatest benefit from mycorrhizal inoculation was obtained with the least soluble source of iron phosphate. It is suggested that the mycorrhizas were able to explore the soil more thoroughly and hence were able to locate and use the point sources of phosphorus in the insoluble iron phosphates.

Importance of cereal phytase activity for phytate phosphorus utilization by growing pigs fed diets containing triticale or corn

Abstract: In contrast to corn, wheat and triticale exhibit high phytase activities. This enzyme enhances phytic phosphorus availability, as demonstrated in pigs given wheat diets. To study the utilization of triticale phosphorus in pigs, the importance of dietary phytase content and the mineral and bone disorders related to high phytate feeding, a nutritional experiment was carried out in 12 growing pigs fed either a corn- or a triticale-based diet for 6 wk. The diets were almost identical except for the cereal component; their phosphorus contents were low (0.4%) and mainly phytic. The following parameters were measured: calcium and phosphorus balances, bone and plasma contents of calcium and phosphorus, plasma vitamin D metabolites and parathyroid hormone (PTH), bone bending moments and intestinal phosphatase activities. Both diets provoked a phosphorus deficiency, but hypophosphatemia occurred less rapidly, hypercalciuria and hypophosphaturia were less marked and phosphorus availability was greater when the triticale diet was fed. This was attributed to the high phytase content of triticale because intestinal phytase and alkaline phosphatase activities were similar in pigs fed either diet. Calcium absorption was not modified by calcium retention was greater for pigs fed triticale and led to higher bone scores. In conclusion, the higher the phytase activity of the diet, the greater the phytate P availability and the lower the bone-mineral disorders.

Variations in soil phosphorus in the fynbos biome, South Africa.

Abstract: SUMMARY (1) The phosphorus composition of the main soils of the dominant vegetation categories of the fynbos biome, south-western Cape, South Africa was studied. (2) Total, Bray No. 2 and resin-extractable phosphorus, pH and organic matter varied significantly between the soils with the Fernwood soils of the strandveld vegetation containing the highest total (338-422 ,ug g-' dry mass) and resin-extractable (13-40 ug gdry mass) phosphorus concentrations. (3) Organic phosphorus was only 10-15% of total phosphorus in the Fernwood soils of strandveld but was 58-77% in the soils of the other vegetation categories. (4) On the west coast, a gradient of soil texture, bulk density and phosphorus status occurred along a 2-km transect from the coastal dunes inland, through strandveld vegetation, vegetation infested with Acacia cyclops and into sand plain lowland fynbos. (5) A significant decrease in the proportion of calcium-bound and increases in ironbound and saloid fractions of inorganic phosphorus and organic phosphorus occurred along the 2-km transect. (6) Litter phosphorus concentrations declined from the coastal dunes inland through strandveld and sand plain lowland fynbos but there were peaks in foliage projective cover, ground litter mass and soil phosphorus concentrations in A. cyclops invaded strandveld. (7) The phosphorus status of the soils of the south-western Cape excluding the Fernwood soils of the strandveld and the alluvial soils of limestone lowland fynbos is low.

Decomposition and nutrient release in needle litter from nitrogen‐fertilized scots pine (pinus sylvestris) stands

Abstract: Decomposition of Scots pine needle litter originating from five stands treated with different amounts of nitrogen fertilizer was measured over a 4‐year period in a mature Scots pine forest. The litter types, which differed in initial concentrations of nitrogen, phosphorus, potassium, and sulfur, but not in gross organic composition, were studied with respect to mass loss, ingrowth of total fungal mycelium, and net release of nutrients. During the first year of decomposition, rates of mass loss and ingrowth of fungal mycelium were highest in the nutrient‐rich litter. Phosphorus concentration was found to be the main factor affecting mass‐loss rate, and the rate of fungal ingrowth was positively correlated with initial nitrogen concentration. After this initial period, decomposition rates decreased, and after 4 years, accumulated mass loss and amounts of fungal mycelium were similar in all five litter types. These findings may be due, in part, to a lower rate of lignin decomposition in nitrogen‐enriched lit...

Phosphorus in the feeding of pigs : effect of diet on the absorption and retention of phosphorus by growing pigs

Abstract: An extensive review is given of the literature concerning phosphorus feeding of pigs. Subjects dealt with are: 1. physiological background, regulation and effect of diet composition and nutrient supply on phosphorus absorption and retention; 2. estimation of the amount of P present in the bodies of pigs using several models and 3. estimations of the P requirements of slaughter pigs from results of balance and slaughter experiments. In the own experiments -using balance, slaughter, digestibility and feeding trials- on growing pigs the following aspects were studied: accuracy of measurements ; P absorption and retention as related to diet composition and nutrient supply; the effects of reduced P supply on performance and, possibly, on locomotory disturbances. It was shown that in phosphorus balance studies, because of carry-over effects, the adaptation period should be at least 21 days when there is a substantial change in phosphorus supply. Effects of dietary energy and protein on P absorption and retention could best be explained by their effect on the daily amount of protein and fat retention. The retention of P measured by the balance was only six per cent (25 + 17 g P) higher than measured by the comparative slaughter technique. Animals with a normal type of daily gain retained 5.0 to 5.1 g P/kg live weight gain, those with a leaner gain 0.2 to 0.3 g P/kg live weight gain more. A technique was described to measure the digestibility of P in various feedstuffs and feed phosphates; substantial differences in digestibility of P between various feedstuffs and feed phosphates were observed. Maximal utilization of P was found at a dietary Ca/digestible P ratio between 2.9 and 3.5. In various feeding trials, leg weakness was not observed any more frequently when slaughter pigs from 30 kg live weight onwards received diets with very low concentrations of phosphorus (g/kg feed) and calcium. However, calcification of the bones was poorer than that of the control animals. Both optimal and just sufficient P requirements for slaughter pigs, were derived. These were expressed as the concentration of digestible P per kg diet.

The role of mosses in the phosphorus cycling of an Alaskan black spruce forest

Abstract: Mosses account for 75% of the annual phosphorus accumulation in aboveground parts of an Alaskan black spruce forest, although they comprise only 17% of the phosphorus pool in aboveground vegetation. Sphagnum subsecundum and feathermosses (Hylocomium splendens and Pleurozium schreberi) have a higher capacity to absorb phosphate than do the fine roots of black spruce (Picea mariana) that are situated beneath the moss layer. In three of the four moss species studied, phosphate absorption capacity increases with increasing age of green tissue and decreases with increasing age of brown tissue. In the two feathermosses, which acquire moisture primarily from the air, and in Sphagnum, phosphate absorption is more rapid in green than in brown tissue. In contrast, the endohydric moss Polytrichum commune, which transports water through stem tissue from soil, absorbs phosphate most rapidly from stems in mineral soil. Two treatments designed to reduce activity of mycorrhizae (cutting of roots extending beneath the moss carpet or application to the moss surface of a fungicide that kills mycorrhizal hyphae) tended to increase phosphate retention by mosses and reduce phosphate transfer out of the experimental plots. This suggests that mycorrhizae are an important avenue of phosphorus movement out of the moss carpet and a means by which the black spruce competes with the overlying mosses for nutrients.

Enhancement of inorganic nitrogen and phosphate release from lake sediment by tubificid worms and chironomid larvae

Abstract: The effects of chironomid larvae and tubificid worms on the release of inorganic nitrogen and phosphorus from a eutrophic freshwater lake sediment were evaluated experimentally using mud-water microcosms. The larvae of Chironomus plumosus L. and Limnodrilus spp. caused an enhancement of inorganic nitrogen release (mainly ammonium nitrogen) from lake sediment. Increasing densities of tubificids markedly influenced release rates. Apparent diffusion coefficients of ammonium at the mud-water interface in microcosms with Limnodrilus spp. increased from 3.5 to 24 x 10-5 cm2 S-1 over a range of 5 densities from 0 to 72500 worms m-2, while that for microcosms with C. plumosus increased from 2.6 to 48 x 10-5 cm2 s-1 over a range of 5 densities from 0 to 6800 larvae m-2. Chironomids and tubificids also had an accelerating effect on phosphate release. Phosphate release rates became greater with an increasing density of organisms. Chironomids induced some enhancement of the release rate at low densities but caused a suppression at high densities. The excretion: release ratios indicated the importance of bioturbation for ammonium release and the importance of excretion for phosphate release.

Automatic method for the determination of ortho-phosphate and total dissolved phosphorus in the marine environment

Abstract: An automatic method for the determination of ortho-phosphate in seawater is described. It is based on the original molybdenum blue method and is very sensitive because of the very small dilution of samples by reagents. An all-glass reaction manifold is proposed, the use of plastic material should be avoided as far as possible. The described method may also be used in a slightly modified version for the determination of total dissolved phosphorus, when samples are first digested with peroxidisulfate. Orthophosphate and total dissolved phosphorus can be determined exactly in the concentration range from 0.01–5 μg at P/l with a sampling frequency of 30 h−1.

Occurrence of phosphorus and its potential remohilization in the littoral sediments of a productive English lake

Abstract: SUMMARY. 1. Vertical profiles of pH were measured at nine shallow water (<5m) locations in Esthwaite Water. These indicate strong gradients of pH near the sediment water interface suggesting a marked buffering capacity of the sediments. 2. Thirteen littoral sediment cores were horizontally sectioned and sequentially extracted (0.5 M NaHCO3, 0.1 M NaOH, 1 M HCI) and analysed for soluble reactive phosphorus. The core sections were also analysed for total phosphorus and per cent organic content to determine the vertical and areal variability of phosphorus within the littoral sediments of Esthwaite Water. 3. The rate of release of phosphorus from intact sediment cores was measured in the laboratory as a function of the pH of overlying water, yielding the relationship log K=0.54 pH−3.94, K=mg Pm−2day−1. The maximum release rate measured was 75 mg P m−2 day−2 at pH = 10.5. 4. Experiments on sediment slurries indicate that the release of phosphorus at pH 10 is rapid with approximately 50% of the total NaHCO3+ NaOH extractable phosphorus being released within 3 h. 5. Phosphorus release from the littoral sediments may equal or exceed external sources plus hypolimnetic inputs during periods of high pH associated with times of maximum algal biomass.

Nutrient reabsorption efficiency and the response to phosphorus fertilization in the desert shrub Larrea tridentata (DC.) Cov.

Abstract: A field fertilization experiment demonstrated that growth ofLarrea tridentata was not limited by phosphorus, even though soils contained high levels of pedogenic carbonates that can potentially fix high amounts of phosphorus. Nutrient reabsorption efficiencies in unfertilized shrubs ranged from 72–86% for P, making nutrient reabsorption a very effective nutrient conservation mechanism. Absolute amounts of N and P reabsorption increased with N and P concentrations in leaves, with reabsorption being greater during drought stress than during rapid leaf growth. However, only N reabsorption efficiency increased with increasing plant N status. A model was developed to explain patterns of nutrient reabsorption efficiencies over large gradients in nutrient availability.

Response of Lake Ontario to Reductions in Phosphorus Load, 1967–82

Abstract: Total phosphorus (TP) loading to Lake Ontario has declined from 14 600 t∙yr−1 in 1969 to 8900 t∙yr−1 in 1982. Midlake spring TP has responded rapidly to these reductions, decreasing at the rate of ...

Manure as a source of nitrogen and phosphorus in soils

Abstract: Nitrogen (N) and phosphorus (P) are present in manure as various inorganic and organic compounds. The distribution of N and P between these compounds depends on the origin of the manure (the species, age and production level of the animal and the corresponding composition of their diets), on the housing, manure collection and manure storage systems and on any possible manure treatment. During storage of slurry the composition moves towards 40–70% of total N being present as ammonium-N (NH 4 + -N) and, more slowly, towards 80–90% of total P being present as calcium phosphates.

Exchange of Nutrients Between Sediments and Water After 15 Years of Experimental Eutrophication

Abstract: Increases in the concentrations of nitrogen and phosphorus occurred in the water column of Lake 227 during 15 years of fertilization with phosphoric acid and sodium nitrate. The sources of the incr...

The relationship between chemically analyzed phosphorus fractions and bioavailable phosphorus1

Abstract: To identify available phosphorus, phosphorus was measured by 2-week bioassay in water from 39 sites in Ontario and Quebec and regressed against total phosphorus and the phosphorus (P) in 11 analytically measured fractions (total soluble, total reactive, particulate, and soluble reactive P, both before and after autoclaving; and soluble reactive P after exposure to enzymes, to UV radiation, and to both). Covariance analysis showed that low-P (~30 pg TP liter-‘) lakes and rivers, P-rich lakes, and P-rich rivers required separate analysis. Total P was a consistently poor correlate of available P (? = 0.44-0.72). A best estimator for various subsets of the data was identified in terms of descriptive power (r2, F), normality, and analytical ease. At low concentrations of P, the fraction of choice is total reactive phosphorus, which explained 73% of the total variation in bioassay P. Total soluble phosphorus was the most useful correlate of bioassay P in eutrophic lakes (r2 = 0.98) and rivers (r2 = 0.95). The applicability of these regressions to waters other than those sampled or as predictors of lake eutrophication remains to be cvaluatcd.

Interaction of phosphorus, carbon, manganese, and chromium in intergranular embrittlement of iron

Abstract: Vacuum melted electrolytic iron and alloys of Fe–P, Fe–Mn, Fe–Cr, Fe–Mn–P, and Fe–Cr–P were employed in a study of the effects of chromium and manganese on phosphorus segregation and intergranular embrittlement. The effects of carbon were examined by hydrogen-decarburization of the original low carbon (10–60 ppm) alloys. The critical fracture stress was measured by pure bending of notched bars at 133 K, and the grain boundary compositions were measured by Auger electron spectroscopy. Manganese was found to segregate in the absence of phosphorus and to be a powerful embrittling element. Carbon was found to exert a great intergranular strengthening effect. It also interfered with the segregation of phosphorus; the latter effect was reduced by the presence of chromium, in agreement with the prior report of Erhart and Grabke. In decarburized alloys the presence of manganese caused increased phosphorus segregation but not when carbon was present at 10–30 ppm. Segregation of manganese and chromium were ...