Showing papers on "Phosphorus published in 1989"

Evidence for sulphate-controlled phosphorus release from sediments of aquatic systems

Abstract: SEDIMENTS of aquatic systems play a critical part in controlling phosphorus loading to the water column1. Because P loading is an important determinant of productivity in aquatic systems, there has been keen interest in variables that influence P release from sediments. In disagreement with present theories1,2 our data from 23 different aquatic systems indicate that sulphate concentration of waters is an extremely important variable controlling P release from sediments. The increased P release from sediments at higher sulphate concentrations may help to explain why primary production in freshwater systems (with relatively low sulphate concentrations) tends to be P limited3, whereas in many saline systems (with high sulphate concentrations) production is often P sufficient4. Further, our results indicate that anthropogenically induced changes from atmospheric S inputs could, over time, alter the P cycle of aquatic systems.

Lake restoration by reducing external phosphorus loading: the influence of sediment phosphorus release

Abstract: SUMMARY. 1. This review considers the factors which determine the recovery of eutrophic lakes following a reduction in the external phosphorus loading. 2 The mean phosphorus content of a lake should decrease roughly in proportion to the reduction in phosphorus input. Where the lake phosphorus concentration does not decrease as predicted, then the release of phosphorus from the sediment is implicated. 3. The current understanding of the processes by which sediment phosphorus is mobilized and transported into the photic zone is described. The extent to which phosphorus release can maintain lake phosphorus concentrations following the reduction in external loading is influenced by: lake morphometry, flushing rate, sediment type, trophic state and history of enrichment. 4. A reduction in the phytoplankton biomass of a lake is dependent upon the size of the decrease in lake phosphorus concentration and the degree to which phosphorus limits primary production. The importance of phosphorus in limiting phytoplankton production tends to decrease with increasing lake trophic status. 5. Improvements in the condition of highly eutrophic lakes require very large reductions in external phosphorus loading, whereas in mildly enriched lakes moderate changes in the supply of phosphorus have noticeable effects on phytoplankton biomass.

Physiologic regulation of the serum concentration of 1,25-dihydroxyvitamin D by phosphorus in normal men.

Abstract: We asked this question: in normal humans, is either a normal dietary intake or normal serum concentration of phosphorus a determinant of the serum concentration of 1,25(OH)2D? In seven normal men whose dietary phosphorus was decreased from 2,300 to 625 mg/d, each intake for 8-9 d, under strictly controlled, normal metabolic conditions, we measured serum concentrations of 1,25(OH)2D daily, and concentrations of phosphorus hourly throughout a 24-h period, before and after restriction. Decreasing dietary phosphorus induced: (a) a 58% increase in serum levels of 1,25(OH)2D; (b) a 35% decrease in serum levels of phosphorus measured in the afternoon; (c) a 12% decrease in the 24-h mean serum level of phosphorus; but, (d) no decrease in morning fasting levels of phosphorus. Serum concentrations of 1,25(OH)2D varied inversely and significantly with 24-h mean concentrations of phosphorus (r = -0.77, P less than 0.001). When these data are combined with those of our prior study in which dietary phosphorus was varied over an extreme range, the relationship between serum levels of 1,25(OH)2D and 24-h mean serum levels of phosphorus is even stronger (r = -0.90, P less than 0.001). In the aggregate, the results demonstrate that in normal men, dietary phosphorus throughout a normal range and beyond, can finely regulate the renal production and serum concentration of 1,25(OH)2D, and provide evidence that this regulation is mediated by fine modulation of the serum concentration of phosphorus.

Reduction of dietary phosphorus absorption by phosphorus binders. A theoretical, in vitro, and in vivo study.

Abstract: Antacids used to decrease phosphorus absorption in patients with renal failure may be toxic. To find more efficient or less toxic binders, a three-part study was conducted. First, theoretical calculations showed that phosphorus binding occurs in the following order of avidity: Al3+ greater than H+ greater than Ca2+ greater than Mg2+. In the presence of acid (as in the stomach), aluminum can therefore bind phosphorus better than calcium or magnesium. Second, in vitro studies showed that the time required to reach equilibrium varied from 10 min to 3 wk among different compounds, depending upon solubility in acid and neutral solutions. Third, the relative order of effectiveness of binders in vivo was accurately predicted from theoretical and in vitro results; specifically, calcium acetate and aluminum carbonate gel were superior to calcium carbonate or calcium citrate in inhibiting dietary phosphorus absorption in normal subjects. We concluded that: (a) inhibition of phosphorus absorption by binders involves a complex interplay between chemical reactions and ion transport processes in the stomach and small intestine; (b) theoretical and in vitro studies can identify potentially better in vivo phosphorus binders; and (c) calcium acetate, not previously used for medical purposes, is approximately as efficient as aluminum carbonate gel and more efficient as a phosphorus binder than other currently used calcium salts.

Sigmoid relationships between nutrients and chlorophyll among lakes

Abstract: Previous studies of freshwater eutrophication have shown that algal biomass tends to increase with the supply of dissolved phosphorus. This concept has been condensed into empirical relationships b...

Determination of plant-available phosphorus by the iron hydroxide-impregnated filter paper (Pi) soil test

Abstract: The use of iron hydroxide-impregnated filter paper (Pᵢ) strips as a collector for phosphorus (P) in soil suspension offers a new approach to soil testing for plant-available P To correlate the Pᵢ test with crop response, four soils ranging in pH from 45 to 82 were incubated with three rates of P either as triple superphosphate (TSP) or central Florida phosphate rock (CFPR), and P was measured in these soils by the Pᵢ, Bray 1, Bray 2, double acid, Olsen, water, and resin extraction methods Two successive crops of maize (Zea mays L) were grown on these soils in greenhouse pots, and the dry matter yield and P uptake by maize were correlated with the soil test values The Pᵢ gave highly significant correlation with crop response in all four soils Across all soils, P source, rates of application and crops, Pᵢ gave the best correlation (0870) with P uptake and dry matter yield The next best correlation with dry matter yield was that of Olsen extractable P The Pᵢ test showed potential as a tool for prediction of P fertilizer requirements in soils

Carbon, nitrogen and phosphorus processing by an oyster reef

Abstract: Simultaneous annual fluxes of carbon, nitrogen and phosphorus were studied on an intertidal oyster reef In Bly Creek, South Carolina, USA. We observed material fluxes every 10.2 d (33 tidal cycles) over 1 yr and used regression estimation to compute annual estimates. The reef appeared to take up 1200 g C m-' yr-' from tidal waters. It had an estimated net removal of 189 g N m-' yr-' from the water column with the majority of this nitrogen released as ammonium (125 g N m-' y ~ ' ) , and a net uptake of 98 g P m-2 yr-l. As indicated by the C : N : P ratio of the fluxes, proportionally more phosphorus was taken up than would be expected. Oyster reefs process carbon, nitrogen und phosphorus at high rates and appear to function as retention mechanisms for nitrogen and phosphorus in estuaries.

A suggested fractionation scheme of inorganic phosphorus in calcareous soils

Abstract: On the basis of a critical review on conventional fractionation schemes of inorganic phosphate and further study of chemical behaviors of Ca-P and Fe-P in calcareous soils, a systematic scheme for the separation of soil inorganic phosphates in calcareous soils is suggested. In the scheme calcium phosphate is classified into dicalcium phosphate, octacalcium phosphate and apatite types, and Ca2-P is extracted by NaHCO3 solution, Ca8-P by NH4Ac, Al-P by NH4F, Fe-P by NaOH-Na2CO3, occluded-P by Na3Cit-Na2S2O4-NaOH, and Ca10-P by H2SO4. Synthetic phosphates prepared of which the chemical and physical assay show good consonance with the theoretical value were used in experiment, the recovery rates of the phosphates added into the calcareous soils by specific extractants is at the range of 85–99%.

Phosphorus and nitrogen retention in five Precambrian shield wetlands

Abstract: Phosphorus and nitrogen mass balances of five wetlands (two beaver ponds, two conifer-Sphagnum swamps and one sedge fen) situated in three catchments in central Ontario, Canada, were measured. Monthly and annual input-output budgets of total phosphorus (TP), total nitrogen (TN), total organic nitrogen (TON), total inorganic nitrogen (TIN), ammonium ion (NH4 + -N), nitrate (NO 3 − -N) and dissolved organic carbon (DOC) were estimated for the five wetlands during the 1982–83 and 1983–84 water years. Except for the deepest beaver pond (3.2 m) which had annual TP retention of −44% (−0.030 ± 0.015 g m−2 yr−1), the wetlands retained < 0.001 to 0.015 g M−2 yr−1 ; however, this wasless than 20% of the inputs and the estimated budget uncertainties were equal to or greater than the retention rates. Annual TN retentions ranged from −0.44 to 0.56 g m−2 yr−1 (−12 to 4%) but were not significantly different from zero. The wetlands transformed nitrogen by retaining TIN (16 to 80% RT) and exporting an equivalent amount as TON (−7 to 102% RT). The beaver ponds, however, retained NO 3 − while NH 4 + was passed through or the outputs exceeded the inputs. In contrast, the conifer swamps retained both NH 4 + and NO 3 − . DOC fluxes into and out of the beaver ponds were equal (−18 and 4% RT) but output from the conifer swamps exceeded input by > 90%. Marked seasonal trends in nutrient retention were observed. Nutrient retention coincided with low stream flow, increased evapotranspiration and biotic uptake during the summer. Net nutrient export occurred during the winter and spring when stream flows were highest and biotic uptake was low.

Nitrogen and phosphorus release from decomposing litter in relation to the disappearance of lignin

Abstract: Concentrations of nitrogen, phosphorus, and acid insoluble substances were followed in decomposing forest foliage litters in some different forest biomes and in a laboratory study. In all cases, th...

Effect of the time of administration of calcium acetate on phosphorus binding.

Abstract: Phosphorus binders are given to patients with renal failure to increase gastrointestinal excretion of phosphorus. To determine the relative importance of the binding of dietary as compared with endogenous phosphorus and to determine the optimal dose schedule, we gave either 4.4 g of calcium acetate (25 mmol of calcium) or a placebo to six normal subjects on each of seven different schedules in a randomized sequence. The net gastrointestinal balance of phosphorus and calcium was determined by a one-day lavage technique. After a meal containing approximately 12 mmol of phosphorus, the mean phosphorus absorption (+/- SE) measured 9.17 +/- 0.36 mmol (78 percent) with placebo but decreased to 3.81 +/- 0.58 mmol (31 percent) when calcium acetate was given immediately before the meal (representing binding of 5.36 +/- 0.77 mmol of phosphorus). Similar binding was observed when calcium acetate was given immediately after the meal and when half the dose was given before and half after the meal. In contrast, when calcium acetate was given two hours after the meal or while the subject was fasting, phosphorus binding was reduced to 2.00 +/- 0.52 mmol and 1.81 +/- 0.84 mmol, respectively. Calcium absorption from calcium acetate averaged 21 +/- 1 percent when the binder was given with a meal; absorption from calcium acetate averaged 40 +/- 4 percent when the binder was given while the subject was fasting. We conclude that calcium acetate increases fecal excretion of phosphorus by binding both dietary and endogenous phosphorus, but the binding of dietary phosphorus is quantitatively much more important. For the most efficient phosphorus binding, calcium (and presumably other phosphorus-binding cations) should be given with meals.

Influence of atmospheric pollution on nutrient limitation in the ocean

Abstract: IN the midst of the debate over the ocean being phosphorus- or nitrogen-limited1,2, the 'acid rain' controversy prompted studies related to the atmospheric transport and delivery of pollutant nitrogen compounds over the ocean3–9. Some of those investigations concluded that atmospheric nitrogen had only minimal effects on euphotic-zone productivity7,8 or on nitrate at the Atlantic thermocline9, thus suggesting a negligible oceanic role for pollutant atmospheric nitrogen. Here I give evidence to the contrary, by clearly showing that, whereas nitrogen limitation is much more prevalent than phosphorus limitation in the surface ocean, those areas with the strongest indications of phosphorus limitation in the North Atlantic and North Pacific are downwind of the most populated and urbanized regions of eastern Asia and North America. This geographic coincidence and the timing and composition of atmospheric nitrogen deposition suggest a plausible, albeit untested, mechanism whereby airborne pollutant nitrogen can lead to phosphorus limitation.

Roots versus shoots in nutrient uptake by aquatic macrophytes in flowing waters

Abstract: Transplant experiments conducted in the South Saskatchewan River, Saskatchewan, Canada showed that the aquatic macrophyte, Potamogeton crispus, obtained most of its nutrients through the roots. When plants were grown in buckets containing high (602 μg∙g−1 total phosphorus; 712 μg∙g−1 total organic nitrogen) or low (258 μg∙g−1 total phosphorus; 109 μg∙g−1 total organic nitrogen) nutrient sediments and exposed to high (75 μg∙L−1 soluble reactive phosphorus (SRP); 530 μg∙L−1 total dissolved nitrogen (TDN), or low (10 μg∙L−1 SRP; 323 μg∙L−1 TDN) nutrient concentrations in the open water, biomass, shoot density and tissue nutrient concentrations were largely determined by sediment type, rather than open water chemistry. These results indicate that the roots are an important site of nutrient uptake for aquatic macrophytes in flowing waters.

Oil-soluble phosphorus antiwear additives for lubricants

Abstract: Oil-soluble reaction products of inorganic phosphorus containing acids or anhydrides with a boron compound and ashless dispersants such as alkenyl succinimides are useful as antiwear/EP additives in lubricants.

Phosphorus, Nitrogen, and Carbon Dynamics of Experimental Lake 303 during Recovery from Eutrophication

Abstract: Little is known about the recovery of lakes from eutrophication, especially as it effects the cycling of nutrients other than phosphorus. We fertilized a naturally oligotrophic lake (Lake 303) in t...

The vegatation, surface water chemistry and peat chemistry of moderate-rich fens in central Alberta, Canada

Abstract: The non-forested fens of the Athabasca area in central Alberta, Canada are characterized by their surface water and peat chemistry. Correlations between vegetation and chemical gradients are examined. The primary vegetation gradient is from stands dominated byDrepanocladus vernicosus, Meesiatriquetra, Menyanthes trifoliata, andCarex chordorrhiza to those dominated byBrachythecium mildeanum, Drepanocladus aduncus, Carex aquatilis, andDrepanocladus polycarpus. This vegetation gradient reflects a chemical gradient of increasing pH, magnesium, sodium, sulphur, organic nitrogen, and phosphorus in the fen water and increasing magnesium, iron, and phosphorus in the fen peats. Potassium and sodium in the fen peats show a decreasing trend along the vegetation gradient. A second gradient from shrub-moss vegetation to sedge-moss vegetation is significantly correlated with microtopography and an increase in nitrate content in the spring (May) waters. The fen waters in this study are in the 5.3–7.1 pH range, with specific conductance of 18–240μS. The calcium contents of the waters averages 19.5–22.1 mg/l and that of magnesium averages 4.3–5.3 mg/l in spring and fall, respectively. The subsurface fen peats are characterized by mean calcium contents of 17,426 mg/kg and magnesium contents of 1,719 mg/kg. Organic nitrogen, nitrate, and ammonium content in the spring and fall waters average 1,967–2,395 μg/l, 3.1–9.8 μg/l, and 16.8–88.9 μg/l, respectively.

31P-Nuclear Magnetic Resonance Determination of Phosphate Compartmentation in Leaves of Reproductive Soybeans (Glycine max L.) as Affected by Phosphate Nutrition

Abstract: Most leaf phosphorus is remobilized to the seed during reproductive development in soybean. We determined, using 31P-NMR, the effect phosphorus remobilization has on vacuolar inorganic phosphate pool size in soybean (Glycine max [L.] Merr.) leaves with respect to phosphorus nutrition and plant development. Phosphate compartmentation between cytoplasmic and vacuolar pools was observed and followed in intact tissue grown hydroponically, at the R2, R4, and R6 growth stages. As phosphorus in the nutrient solution decreased from 0.45 to 0.05 millimolar, the vacuolar phosphate peak became less prominent relative to cytoplasmic phosphate and hexose monophosphate peaks. At a nutrient phosphate concentration of 0.05 millimolar, the vacuolar phosphate peak was not detectable. At higher levels of nutrient phosphate, as plants progressed from the R2 to the R6 growth stage, the vacuolar phosphate peak was the first to disappear, suggesting that storage phosphate was remobilized to a greater extent than metabolic phosphate. Under suboptimal phosphate nutrition (≤ 0.20 millimolar), the hexose monophosphate and cytoplasmic phosphate peaks declined earlier in reproductive development than when phosphate was present in optimal amounts. Under low phosphate concentrations (0.05 millimolar) cytoplasmic phosphate was greatly reduced. Carbon metabolism was coincidently disrupted under low phosphate nutrition as shown by the appearance of large, prominent starch grains in the leaves. Cytoplasmic phosphate, and leaf carbon metabolism dependent on it, are buffered by vacuolar phosphate until late stages of reproductive growth.

Seasonal dynamics of a cyanobacteria-dominated microbial community in surface sediments of a shallow, eutrophic lake

Abstract: The seasonal variation of microbial biomass and activity in the surface sediments (0–10 cm) of the shallow, eutrophic Lake Vallentunasjon was followed during one year. “Overwintering”Microcystis colonies dominated the microbial community during all seasons, constituting 60–90% of the total microbial biomass. Expressed on an areal basis, the benthic biomass was, throughout the year, larger than or similar to the planktonic biomass during the peak of the summer bloom, indicating an ability of the colonies to survive in the sediments for extended periods. Abundance of “other”, non-photosynthetic bacteria varied in the range 3.0–15.5 · 1010 cells g−1 d. w. over the year with minimum values in summer and maximum values in autumn in connection with the sedimentation of theMicrocystis bloom. A substantial part of the non-photosynthetic bacteria, up to circa 40%, was associated with the mucilage of healthyMicrocystis colonies. Bacterial production (3H-thymidine incorporation) appeared to be strongly temperature dependent and less influenced by the seasonal sedimentation pattern. Our data indicate an increasing proportion of non-growing cells in autumn and winter. Biomass-bound phosphorus constituted a significant portion, circa 10%, of the phosphorus content in Lake Vallentunasjon sediments. This pool has normally been overlooked in studies on phosphorus dynamics in lake sediments. Different mechanisms whereby organic phosphorus can be released from the sediments are discussed.

Prediction of Soluble Phosphorus Transport in Agricultural Runoff

Abstract: Estimation de la concentration du phosphore soluble dans des eaux de ruissellement en utilisant les relations entre les cinetiques de desorption du phosphore dans le sol et la profondeur effective de cette interaction du sol avec l'eau

Preparation of Black Phosphorus Single Crystals by a Completely Closed Bismuth-Flux Method and Their Crystal Morphology

Abstract: Needle-shaped and film- or plate-shaped black phosphorus single crystals were prepared by an improved bismuth-flux method. The conversion of red phosphorus to white phosphorus and the growth of black phosphorus single crystals from the solution of white phosphorus in liquid bismuth were performed in an evacuated quartz-glass apparatus without breaking the vacuum. Needle crystals measured about 5 mm in length and 10 to 100 µm in thickness. The thickness of film or plate crystals ranged from 1 to 10 µm and the width was usually above 100 µm, generally increasing with decreasing thickness. Some crystal morphologies were observed and analyzed crystallographically.

31P-NMR analysis of phosphorus compounds in extracts of surface soils from selected karri (Eucalyptus diversicolor F. Muell.) forests

Abstract: Phosphorus compounds in concentrated extracts of a range of highly-weathered Karri forest soils were identified and quantified by 31 P-NMR. The extracts were prepared using a chelating, cation-exchange resin in preference to NaOH extraction as the former proved more suitable for use with NMR analysis. Concentrations of alkali- or resin-extractable P in the soils of this study were about an order of magnitude less than in soils which have been used in previous 31 P-NMR studies of soil-P. As forest age increased, the proportion of extracted-P present in forms other than inorganic orthophosphate also increased. Monoester-P was the largest fraction of the extracted organic-P followed by diesters, pyrophosphate and traces of polyphosphates and phosphonates. Sugar phosphates (e.g. glucose-6-phosphate or ribose-5-phosphate), as well as inositol-P and choline-P, resonate at frequencies similar to those measured for soil monoesters. Buffered cation exchange resins may be useful in future studies of highly-weathered soils.

Phosphorus-31 and Nitrogen- 14 NMR Studies of the Uptake of Phosphorus and Nitrogen Compounds in the Marine Macroalgae Ulva lactuca

Abstract: Cytoplasmic phosphomonoesters and inorganic phosphate, as well as vacuolar inorganic phosphate and polyphosphates, gave rise to the major peaks in (31)P nuclear magnetic resonance (NMR) spectra of the marine macroalgae Enteromorpha sp., Ceramium sp., and Ulva lactuca which were collected from the sea. In contrast, NMR-visible polyphosphates were lacking in Pylaiella sp. and intracellular vacuolar phosphate seemed to act as the main phosphorus store in this organism. In laboratory experiments, polyphosphates decreased in growing U. lactuca which was cultivated in continuous light under phosphate-deficient conditions. In contrast, the same organism cultivated in seawater with added phosphate and ammonium, accumulated phosphate mainly in the form of polyphosphates. When nitrate was provided as the only nitrogen source, accumulation of polyphosphates in the algae decreased with increasing external nitrate concentration. From the chemical shift of the cytoplasmic Pi peak, the cytoplasmic pH of superfused preparations of Ulva was estimated at 7.2. The vacuolar pH, determined from the chemical shifts of the vacuolar Pi and the terminal polyphosphate peaks, was between 5.5 and 6.0. The intracellular nitrate and ammonium levels in U. lactuca were determined by (14)N NMR. Both nitrogen sources were taken up and stored intracellularly; however, the uptake of ammonium was much faster than that of nitrate.

Nodulation and growth response of Allocasuarina and Casuarina species to phosphorus fertilization

Abstract: To examine how soil phosphorus status affects nitrogen fixation by the Casuarinaceae —Frankia symbiosis,Casuarina equisetifolia and two species ofAllocasuarina (A torulosa andA littoralis) inoculated or fertilized with KNO3 were grown in pots in an acid soil at 4 soil phosphate levels InoculatedC equisetifolia nodulated well by 12 weeks after planting and the numbers and weight of nodules increased markedly with phosphorus addition Growth ofC equisetifolia dependent on symbiotically fixed nitrogen was more sensitive to low levels of phosphorus (30 mg kg−1 soil) than was growth of seedings supplied with combined nitrogen; at higher levels of phosphorus, the growth response curves were similar for both nitrogen fertilized and inoculated plants The interaction between phosphorus and nitrogen treatments (inoculated and nitrogen fertilized) demonstrated that there was a greater requirement of phosphorus for symbiotic nitrogen fixation than for plant growth when soil phosphorus was low