Showing papers on "Phosphorus published in 1990"

Phosphorus and nitrogen limitation of phytoplankton growth in the freshwaters of North America : a review and critique of experimental enrichments

Abstract: While phosphorus is generally considered to be the primary nutrient limiting algal growth in lakes, limitation of algal growth by nitrogen has been observed in freshwater. It is also commonly obser...

Seagrass nutrient content

Abstract: Data on nutrient contents of 27 seagrass species at 30 locations were compiled from the literature. Mean (f SE) concentrations of carbon, nitrogen and phosphorus in seagrass leaves were 33.6 2 0.31, 1.92 f 0.05, and 0.23 2 0.011 % dry wt, respectively. The median C:N:P ratio was 474 :24: 1, which represents a C:P ratio more than 4 times, and a N:P ratio more than 1.5 times that of oceanic seston. These ratios are, however, less than those previously reported for marine macrophytes (550 : 30 : 1) by Atkinson & Smith (1984). Nitrogen and phosphorus variability within species was large, but carbon contents exhibited little variability. Accordingly, carbon:nutrient (N and P) ratios were inversely related to changes in nutrient content, and the rate of change in C:N and C:P ratios with increasing nitrogen or phosphorus content in plant tissues should shift from high to small as nutrient supply meets the plant's demands. The median nitrogen and phosphorus contents reported here (1.8 % N and 0.20 % P as % DW) correctly discriminated between seagrass stands that did or did not respond to nutrient enrichment, thus offering a useful reference for comparisons of seagrass nutrient contents.

Phosphorus uptake by pigeon pea and its role in cropping systems of the Indian subcontinent

Abstract: Pigeon pea was shown to be more efficient at utilizing iron-bound phosphorus (Fe-P) than several other crop species. This ability is attributed to root exudates, in particular piscidic acid and its p-O-methyl derivative, which release phosphorus from Fe-P by chelating Fe3+. Pigeon pea is normally intercropped with cereals under low-input conditions in the Indian subcontinent. Although pigeon pea can utilize the relatively insoluble Fe-P, intercropped cereals must rely on the more soluble calcium-bound phosphorus. This finding suggests that cultivation of pigeon pea increases total phosphorus availability in cropping systems with low available phosphorus.

Influence of organic matter on phosphate adsorption by aluminium and iron oxides in sandy soils

Abstract: SUMMARY The phosphate adsorption capacity (Pmax) of samples from various horizons of five Danish podzolized soils were investigated before and after organic matter removal. Removal of organic matter had no direct influence on Pmax suggesting that organic matter did not compete with phosphate for adsorption sites. In the soils investigated aluminium and iron oxides were the main phosphate adsorbents. Thus, more than 96% of the variation in Pmax could be accounted for by poorly crystalline aluminium and iron oxides (extractable by oxalate) and by well-crystallized iron oxides (taken as the difference between dithionite-citrate-bicarbonate-extractable iron and oxalate-extractable iron). Organic matter affected phosphate adsorption indirectly by inhibiting aluminium oxide crystallization. The resulting poorly crystalline oxides had high Pmax. In contrast, the influence of organic matter on the crystallinity of the iron oxides, and therefore on their capacity to adsorb phosphate, seemed limited.

Relative Importance of Phosphorus Supply to Phytoplankton Production: Fish Excretion versus External Loading

Abstract: In laboratory tanks with bream (Abramis brama), perch (Perca fluviatilis), and roach (Rutilus rutilus) concentrations of phosphorus and nitrogen increased with time. Phosphorus was mainly released as soluble molybdate-reactive phosphorus (SRP); nitrogen almost exclusively as ammonium. The release increased with the species' tendency to forage on littoral sediments and with a smaller fish size. Bioassays with the test algae Selenastrum capricornutum showed that released phosphorus was readily available to algal growth. The total supply of phosphorus to the epilimnion of Lake Gjersjoen was calculated from the external supply from the tributaries and the estimated phosphorus release from total roach biomass. From May to October 1980 phosphorus release from the roach population contributed about the same order of magnitude as the total phosphorus loading from the watershed. During the period with the most serious phosphorus depletion to the phytoplankton (July, August, and September), the phosphorus supply fr...

Nitrogen and phosphorus mineralization in fens and bogs.

Abstract: The release of inorganic nitrogen and phosphorus in ten mires in The Netherlands with different vegetation and hydrology was measured by incubating soil in situ in polyethylene bottles at depths of 10 and 25 cm. At the same time, cellulose decomposition was estimated by means of tensile strength loss of in-situ cotton strips. The size of the inorganic N pool was not related to depth, mire type or the presence of a Sphagnum cover. The labile inorganic P pool was significantly larger in Sphagnum-dominated bogs than in phanerogram-dominated fens (...)

Chemical nature of organic phosphorus in cultivated and uncultivated soils under different environmental conditions

Abstract: SUMMARY A sequential alkali extraction procedure followed by ultrafiltration and quantitative 31P nuclear magnetic resonance (NMR) spectroscopy was used to examine organic phosphorus in a Brown Chernozem, and an adjacent Gleysol developed under native prairie vegetation, and a Grey Luvisol formed under aspen forest in Saskatchewan, Canada. Differences in the nature of organic P in the native soils were related to moisture status and vegetation. In the grassland soils, a greater proportion of orthophosphate diester P was found in the bottom-slope Gleysol. This difference was partly attributed to less favourable conditions for mineralization in the bottom slope soil compared with the mid-slope Brown Chernozem. Teichoic acid P occurred only in the native Grey Luvisol (NMR δ p.p.m. 0.36-0.95) under boreal forest and not under native grassland. At all three sites, soils under long-term cultivation were also examined and while orthophosphate monoester P (83.4-94.6% total Po), orthophosphate diester P (3.9–8.7% total Po) and teichoic acid P (12.7% total Po in forested Grey Luvisol) were detected in native soils, only orthophosphate monoester P was found in the corresponding soils that had been cultivated for 70–80 years. These findings suggest that orthophosphate diester P and teichoic acid P are more readily mineralized in the soil environment than orthophosphate monoester P forms.

Phosphorus-limited growth of the tropical seagrass Syringodium filiforme in carbonate sediments

Abstract: Seagrasses, along with all other marine primary producers, are generally considered to be nitrogen limited. Now experimental enrichments of the tropical seagrass Synngodium fihformeKutz. show that phosphorus, rather than nitrogen, can be the primary limiting nutrient in a marine carbonate environment. Phosphorus enrichment of carbonate sediments resulted in dramatic increases in seagrass growth, biomass, and tissue phosphonis con~position. Additionally, rhizosphere nitrogeil fixation increased in response to phosphorus enrichment, potentially making more nitrogen available to the plants.

A comparison of phosphorus immobilization in sediments of freshwater and coastal marine systems

Abstract: The extent to which sediments of aquatic systems immobilize or release phosphorus can affect dramatically the P content of overlying waters. Data from 48 different aquatic systems suggests that there may be a major difference between fresh- and salt-water systems in this immobilization. Under oxic conditions (water overlying sediments had dissolved oxygen > 0.5 mg/L) P is strongly immobilized in sediments of most fresh-water systems. In sediments of most salt-water systems P is released from sediments and behaves, essentially, as a conservative tracer of benthic decomposition. This difference in P cycling is large enough to have an influence on the often cited difference in phytoplankton nutrient limitation between fresh- and salt-water systems.

Bacterial regeneration of ammonium and phosphate as affected by the carbon:nitrogen:phosphorus ratio of organic substrates.

Abstract: The effect of carbon∶nitrogen∶phosphorus (C∶N∶P) ratio of organic substrates on the regeneration of ammonium and phosphate was investigated by growing natural assemblages of freshwater bacteria in mineral media supplemented with the simple organic C, N, and P sources (glucose, asparagine, and sodium glycerophosphate, respectively) to give 25 different substrate C∶N∶P ratios. Both ammonium and phosphate were regenerated when C∶N and N∶P atomic ratios of organic substrates were ≤10∶1 and ≤16∶1, respectively. Only ammonium was regenerated when C∶N and N∶P ratios were ≤10∶1 and ≥10–20∶1, respectively. On the other hand, neither ammonium nor phosphate was regenerated when C∶N and N∶P ratios were ≥15∶1 and ≥5∶1, respectively. In no case was phosphate alone regenerated. As bacteria were able to alter widely the C∶N∶P ratio of their biomass, the growth yield of bacteria appeared primarily dependent on the substrate carbon concentration, irrespective of a wide variation in the substrate C∶N∶P ratio.

Microstructures and crystallization of electroless Ni-P deposits

Abstract: A study has been made of microstructures and crystallization of the electroless Ni-P deposits containing 11.3 to 23.0 at% P obtained from acidic nickel sulphate baths with sodium hypophosphite as a reducing agent by means of differential scanning calorimetry, X-ray diffractometry and hot stage transmission electron microscopy. The deposits containing low phosphorus content of 11.3 at% could be represented as an fcc Ni-P solid solution of 5 to 10 nm microcrystallites, whereas the deposits containing high phosphorus content were amorphous. The crystallization process of amorphous Ni-P solution involved more than one intermediate phases; precrystallized nickel or off-stoichiometric Ni3(P, Ni) or Ni5(P, Ni)2 phase in which some phosphorus sites are replaced by nickel atoms. The final equilibrium phases were bct Ni3P and fcc nickel crystals regardless of phosphorus content. The amorphous phase containing 20 to 22 at% phosphorus was the most stable among the amorphous Ni-P alloys.

Effect of degree of soil disturbance on mycorrhizal colonization and phosphorus absorption by maize in growth chamber and field experiments

Abstract: SUMMARY Prior studies have established that phosphorus absorption by maize from undisturbed soil is greater than from soil which has been disturbed since the previous period of growth. Those experiments were conducted under controlled conditions and with only two disturbance treatments, namely disturbance of the soil by hand sufficient that it will pass a 5 mm sieve, and no disturbance at all. We present here two experiments in which additional treatments of intermediate degrees of disturbance are included. In a growth chamber experiment, cutting the soil into 1, 2 or 4 cm cubes reduced the phosphorus absorption and shoot dry matter, but the reduction was not as great as that after hand disturbance of the soil. In a field experiment, the phosphorus absorption and shoot dry matter found in a conventional tillage and no-till treatments were less than in hand-planted no-till plots, but greater than with severe soil disturbance. In both experiments increases in shoot dry mass and shoot phosphorus concentration in the less disturbed treatments were not accompanied by an increase in mycorrhizal colonization. This is inconsistent with earlier studies in which colonization was greater in undisturbed soil. Since it has now been demonstrated that increased colonization is not a necessary component in the process whereby lack of disturbance results in improved plant performance, the role of mycorrhizas in this effect should be reconsidered. If mycorrhizas are important in this respect then this can only be by means of changes in the external mycelium. However, without experimental confirmation this interpretation is speculative.

Temperature effects on silicon‐ and phosphorus‐limited growth and competitive interactions among three diatoms1

Abstract: Three diatom species, Stephanodiscus hantzschii (Ehr.) Grun., Asterionella formosa Hass. and Fragilaria crotonensis Kitt. Hass. were isolated from Lake Maarsseveen where they are dominant and show a successional sequence. The physiological responses of each species to temperature and limitation by silicon and phosphorus were determined over the temperature range of 5° to 20° C using short-term batch culture methods. Stephanodiscus hantzschii had higher maximum growth rates than the other two species at all temperatures, and the maximum growth rates of all species increased with increasing temperature. Temperature affected not only maximum growth rates but also half-saturation constants (Ks) and the minimum cell quotas. S. hantzschii had low silicon requirements for growth under Si-limiting conditions, and A. formosa and F. crotonensis had higher and nearly identical silicon requirements. The Ks values for silicon for S. hantzschii were essentially constant from 5° to 20° C but varied greatly for the other two species. A. formosa had the lowest requirements for growth under phosphorus limitation, F. crotonensis was intermediate and S. hantzschii had the highest growth requirements for phosphorus. The K1 values for phosphorus were constant over the temperature range for both A. formosa and F. crotonensis and were much higher and variable for S. hantzschii. Nutrient competition experiments were performed in continuous cultures at four temperatures and various Si:P ratios. The results generally, but not always, confirmed the predictions based on the Monod relationships for each species. Results not in agreement with predictions were usually because of similar physiological properties of A. formosa and F. crotonensis or because of decreased loss rates for F. crotonensis due to wall growth. In cultures with all three species phosphorus-limited (Si:P > 75), A. formosa often dominated as predicted, although F. crotonensis was sometimes the most abundant species. As predicted, S. hantzschii never dominated at high Si:P ratios. At intermediate Si:P ratios when A. formosa and F. crotonensis were both Si-limited and S. hantzschii P-limited, all three species coexisted because A. formosa and F. crotonensis have almost identical silicon requirements, although sometimes F. crotonensis was more abundant than predicted. At 10°C the results agreed best with the predictions; A. formosa dominated at high Si:P ratios and S. hantzschii dominated as predicted at low Si:P ratios when all three species were Si-limited.

Nitrogen, phosphorus and potassium budgets for two small fens surrounded by heavily fertilized pastures.

Abstract: In the Vechtplassen area of The Netherlands, small fens are scattered in an agricultural landscape which is used for dairy production. Fens in groundwater discharge areas have been less affected by eutrophication than those in groundwater recharge areas. Hydrological and nutrient budgets (nitrogen, phosphorus, potassium) were measured in two fens from 1985 to 1987. (...)

Fish manipulation as a lake restoration tool in shallow, eutrophic temperate lakes 1: cross-analysis of three Danish case-studies

Abstract: The use of fish manipulation as a tool for lake restoration in eutrophic lakes has been investigated since 1986 in three shallow, eutrophic Danish lakes The lakes differ with respect to nutrient loading and nutrient levels (130–1000 μg P l−1, 1–6 mg Nl−1) A 50% removal of planktivorous fish in the less eutrophic cyanobacteria-diatom dominated Lake Vaeng caused marked changes in lower trophic levels, phosphorus concentration and transparency Only minor changes occurred after a 78% removal of planktivorous fish in eutrophic cyanobacteria dominated Frederiksborg Castle Lake In the hypertrophic, green algae dominated Lake Sobygard a low recruitment of all fish species and a 16% removal of fish biomass created substantial changes in trophic structure, but no decrease in phosphorus concentration The different response pattern is interpreted as (1) a difference in density and persistence of bloomforming cyanobacteria caused by between-lake variations in nutrient levels and probably also mixing- and flushing rates, (2) a difference in specific loss rates through sedimentation of the algal community prevaling after the fish manipulation, (3) a decreased impact of planktivorous fish with increasing mean depth and (4) a lake specific difference in ability to create a self-increasing reduction in the phosphorus level in the lake water This in turn seems related to the phosphorus loading

Evaluation of Mehlich‐III extractant to estimate the available P in Quebec soils

Abstract: The Mehlich‐III method used for the determination of available P in 82 Quebec soils was compared to five other chemical methods (Bray‐II, Bray‐I, Mehlich‐II, Mehlich‐I and Olsen) and to two anion exchange resin techniques (F‐ and HCO‐ 3) In general, very good correlations were found between Mehlich‐III, Bray‐II and Bray‐I methods on acid soils (r=0.95** and 0.98**). The Mehlich‐III‐P content is somewhat the same as that determined by Bray‐I and corresponds approximately to 80% of Bray‐II‐P. The Mehlich—III extractant was found to be more reliable than Bray‐II and Bray‐I on very acid spodosols having high P‐sorption capacity. The Bray methods, with high NH4F concentration, extracted strongly fixed Al‐P in these soils and may overestimate the available P. In some acid soils containing apatite and in calcareous soils, the Bray‐II and Mehlich‐I (double acid) easily dissolved these Ca‐P compounds and gave exaggerated high P values. The Mehlich‐III and the other methods were less vigourous for these co...

Variation in quality of caribou and reindeer forage plants associated with season, plant part, and phenology

Abstract: Plant parts used as forage by caribou and reindeer (Rangifer tarandus) have been collected in conjunction with studies of foraging dynamics, nutrition, growth, and population ecology of this arctic ungulate over the course of several years in Alaska and other circumpolar areas. These samples were subjected to proximal analyses for percent nitrogen, phosphorus, sodium, carbohydrate, cell wall (NDF), acid detergent fiber (ADF), lignin, cellulose, and residual ash, and treated to determine in vitro and nylon bag dry matter digestibility (DMD). Among winter vascular plant forage only carbohydrates showed a positive correlation with digestibility, wheras in summer nitrogen, phosphorus, and in some cases sodium, also are positively correlated with digestibility. Forage from shrubs and forbs in early summer had higher nitrogen and carbohydrate levels than later in the season, wheras graminoids show an increase in these levels during the first few weeks of growth. Floral parts during anthesis showed higher nitrogen, phosphorus, and carbohydrate levels and higher digestibility than corresponding leaf material. The annual dietary cycle is the product of adjustment of the physiological cycle to seasonal fluctuation in forage quality and quantity.

Handbook of Phosphorus-31 Nuclear Magnetic Resonance Data

Abstract: Use of the Handbook and General Trends. 31P NMR Data of One and Two Coordinate Phosphorus Compounds. 31P NMR Data of Alkali Metal Phosphides. 31P NMR Data of Three Coordinate (l3 s3) Phosphorus Compounds Containing Phosphorus Bonds to Halogen. 31P NMR Data of Three Coordinate (l3 s3) Phosphorus Compounds Containing Bonds to Chalcogenides (O, S, Se, Te) But No Bonds to Halogen. 31P NMR Data of Three Coordinate (l3 s3) Phosphorus Compounds Containing Phosphorus Bonds to Group V Elements (N, P, As, Sb) But No Bonds to Halogens Nor Chalcogenides. 31P NMR Data of Three Coordinate (l3 s3) Phosphorous Compounds Containing Phosphorus Bonds to Group IV Elements and Hydrogen Only. Three Coordinate Five Valent (l5, s3) Compounds. 31P NMR Data of Four Coordinate Phosphonium Salts and Betaines. 31P NMR Data of Four Coordinate Phosphorus Compounds Containing a P=Ch Bond but No Bonds to H or Group IV Atoms. 31P NMR Data of Four Coordinate Phosphorus Compounds Containing a P=Ch Bond and One or Two P-H Bonds. 31P NMR Data of Four Coordinate Phosphorus Compounds Containing a P=Ch Bond and One P-C Bond. 31P NMR Data of Four Coordinate Phosphorus Compounds Containing a P=Ch Bond and Two P-C Bonds. 31P NMR Data of Four Coordinate Phosphorus Compounds Containing a P=Ch Bond and Three Bonds from Phosphorus to Group IV Atoms. 31P NMR Data of Four Coordinate Phosphorus Compounds Containing a Formal Multiple Phosphorus Bond to a Group V Atom. 31P NMR Data of Four Coordinate Phosphorus Compounds Containing a Formal Multiple Bond from Phosphorus to a Group IV Atom. 31P NMR Data of Four Coordinate Phosphorus Compounds Containing a Formal Negatively Charged Atom a to Phosphorus. 31P NMR Data of Phosphoranides. 31P NMR Data of Five Coordinate (l5 s5) Phosphorus Compounds. 31P NMR Data of Six Coordinate Phosphorus Compounds. Index.