Phosphorus Turnover Research Articles

Biogeochemical cycling constraints on stream ecosystem recovery

In systems where production is limited by the availability of a nutrient, nutrient input to and recycling within the system is related to the resilience, or speed of recovery, of a system to its steady state following a disturbance. In particular, it is shown that the return timeT s of the system to steady state, or the inverse of the resilience, is approximately equal to the mean turnover time of the limiting nutrient in the system. From this relationship, it is possible to understand and predict how various properties of food webs and their environments affect resilience. These properties include nutrient input rate, loss rate, size of the detritus compartment, and trophic structure. The effects of these properties on resilience are described by using simple mathematical models. To test model predictions, experimental studies of the response of periphyton-dominated stream ecosystems to disturbance are being conducted on a set of laboratory streams in which nutrient inputs and grazing intensity are regulated at different levels. In streams without snail grazers (low-grazed streams), 90% recirculation of stream water to reduce nutrient inputs resulted in longer turnover times (T r ) of phosphorus within the stream compared with once-through flow. However, in streams with snail grazers (high-grazed streams), there were no differences in phosphorus turnover time between once-through and partially recirculated treatments. Results on the rate of recovery of periphyton from a flood/scour disturbance to each stream partially support the model prediction of a positive relationship between ecosystem return time (T s ) and nutrient turnover time (T r ) within the streams.

Varietal differences in root phosphatase activity as related to the utilization of organic phosphates

This paper presents results of a comparative study of phosphorus utilization from inositol hexaphosphate by various varieties of Phaseolus vulgaris in relation to the activity and characteristics of their root phosphatases. Bean varieties show significant differences in their uptake of phosphorus from inositol hexaphosphate with a clear dependency on the phosphatase activity of their roots at pH 5. The results which are discussed in connection with the phosphorus turnover in the rhizosphere suggest that root phosphatase activity is a significant factor of nutritional efficiency under limited mineral phosphorus supply.

Aspects of the phosphorus cycle in Hartbeespoort Dam (South Africa)

The role of biotic processes in a warm, monomictic, hypertrophic African impoundment (Hartbeespoort Dam) is examined using 32P radiobioassays. Phosphorus demand is assessed by phosphorus turnover times, alkaline phosphatase activity, cellular phosphorus status and the phosphorus deficiency index. Long turnover times indicative of an enriched system were recorded, ranging from 9 h to 1992 h, with no evidence of phosphorus stress being present. These turnover times support the hypothesis that the phosphorus cycle in Hartbeespoort Dam is dominated by the algal community which is shown to play an important role in phosphorus cycling within the water column. However, hydrological processes remain the driving force in phosphorus seasonality in the lake.

The common jellyfish Aurelia aurita: standing stock, excretion and nutrient regeneration in the Kiel Bight, Western Baltic

The population dynamics, ammonia and inorganic phosphate excretion, and nutrient regeneration of the common jellyfish Aurelia aurita was investigated from 1982 to 1984 in the Kiel Bight, western Baltic Sea. During summer 1982, medusae abundance ranged between 14 and 23 individuals 100 m-3, biomass was estimated at about 5 g C 100 m-3 and the mean final diameter of individuals was 22 cm. Abundance, based on numbers, in 1983 and 1984 was an order of magnitude lower; biomass was less than 2 g C 100 m-3 and jellyfish grew to 30 cm. During the summers of 1983 and 1984, A. aurita biomass constituted roughly 40% of that of the total zooplankton>200 μm. In 1982, for which zooplankton data were lacking, it was assumed that medusae biomass was greater than that of all other zooplankton groups. Total ammonia excretion ranged between 6.5 and 36 μmol h-1 individual-1, whereas inorganic phosphate release was 1.4 to 5.7 μmol h-1 individual-1. Allometric equations were calculated and exponents of 0.93 for NH4−N release and 0.87 for PO4−P excretion were determined. Nitrogen and phosphorus turnover rates were 5.4 and 14.6% d-1, respectively. In 1982, the medusae population released 1 100 μmol NH4−N m-2 d-1, about 11% of the nitrogen requirements of the phytoplankton. The inorganic phosphate excretion (150 μmol m-2 d-1) sustained 23% of the nutrient demands of the primary producers. In the other two years the nutrient cycling of the medusae was much less important, and satisfied only 3 to 6% of the nutrient demands. It is suggested that in some years A. aurita is the second most important source of regenerated nutrients in Kiel Bight, next to sediment.

Mobilization and turnover of soil phosphorus in the rhizosphere

AbstractRecent progress in methods enables a better understanding of the turnover of P in the rhizosphere. Examples of this progress are the separation of soil layers differing in proximity to the roots, improved methods for extraction and fractionation of soil P, application of 32P isotope dilution analysis to follow P fluxes between various fractions and direct determination of microbially bound P and of root phosphatases. These methods were combined to investigate the following aspects –labile P pools, the P fluxes between these pools and their contribution to the P supply to growing maize roots –the role of microbial biomass in these interactions and the partition of mobilized P between plants and microorganisms –modifications of sorption and transport of P in the rhizosphere –plant availability of native and added organic phosphates, and the relative significance of root and soil phosphatases. There is a significant transformation of P in the rhizosphere with a corresponding redistribution among fractions of different plant availability. About 9% of the inorganic 32P added to soil were incorporated within 2 weeks into microbial and organic fractions. The transfer of P from non‐exchangeable forms exceeded the depletion of the exchangeable P by a factor of 5. About 53% of the mobilized P originated from inorganic, the remaining 47% from organic fractions. Of the mobilized P 80% was taken up by the plants and 20% was found in the microbial biomass. Up to 90% of the P in the rhizosphere soil solution was organic with a maximum just outside the root zone. Soluble inositol hexaphosphate modified the sorption of inorganic P, thus shifting its equilibrium solution concentration. The phosphatase activity of the roots is considerable. Both root phosphatase activity and the utilization of inositol hexaphosphate depend on the P supply and nutritional status of plants with regard to P.It is concluded that the rhizosphere is a key site of P transformation with a significant mobilization of P from the non‐exchangeable inorganic and organic fractions. Organic P fractions not only play a significant role as a P source but also modify important soil parameters related to the sorption and transport of P in the rhizosphere.

Specific activity measurements to determine phosphorus turnover in bluegill, Lepomis macrochirus

The biological turnover constant for phosphorus was determined in muscle and five other sections of bluegill. Bluegill of average weight 121 g were maintained in a large flowthrough system at 22°–16°C and fed worms, Eisenia foetida, at two feeding levels, ad lib. (which averaged 2.6 g/d per 100-g fish, wet weight), and 1.5 g/d per 100-g fish. The daily phosphorus intakes at the two levels per 100-g fish were 3.1 and 1.8 mg. The average phosphorus concentration was 2.4 mg/g in muscle and 15.4 mg/g in the whole fish. Worm food was spiked with P-32 at increasing daily increments to balance radioactive decay. The radioactive worms were fed daily to the bluegill during the P-32 accumulation period of 51 days. For the next 28 days of depuration, nonradioactive worms were fed. Sets of three bluegill were collected at approximately weekly intervals, sectioned and analyzed for P-32 and phosphorus. All data were reported as specific activity in tissue relative to specific activity in feed, with P-32 count rates corrected for its 14.3-day half life. Phosphorus turnover constants were obtained by three approaches: (1) from the relative specific activity measured near steady state; (2) by fitting an equation for a 1-compartment model to the accumulation and depuration data; and (3) by fitting an equation for a simplified 2-compartment model to the depuration data. The biological turnover constant calculated with all three approaches was 0.004 d−1 for phosphorus in muscle of bluegill fed ad lib.

Phosphorus cycling in wheat-pasture rotations. III. Organic phosphorus turnover and phosphorus cycling

The incorporation of 32P and 33P from 33P-labelled fertilizer and 33P-labelled pasture residues into organic and inorganic fractions of soil P was studied in a solonized brown soil (Calcixerollic xerochrept) cropped to wheat (Triticum aestivum). Most of the plant residue 33P was present as inorganic P at the time it was added to the soil, but only 7 days later almost 40% had been incorporated into organic P fractions of the soil. As the fertilizer was banded near the soil surface at sowing, little of the 32P from the 32P-labelled fertilizer was incorporated into organic forms, even after 95 days. From a knowledge of the P uptake by the plants and microorganisms, an integrated P cycle for this soil under wheat-pasture rotations was developed. We propose that fertilization of the pasture phase of the rotation stimulates the build-up of residual inorganic and organic P, while fertilization of the wheat phase predominantly stimulates the accumulation of inorganic forms of P in the soil.

Utility of Soluble Reactive Phosphorus Measurements in Great Lakes Surveillance Programs: a Summary

This report summarizes the findings and conclusions of a special workshop convened by the National Water Research Institute at Burlington, Ontario, to review differences in opinion regarding the utility and continuation of soluble reactive phosphorus (SRP) measurements in the Great Lakes surveillance programs. SRP measurements were discussed taking into account recent developments in understanding the role of phosphorus in bacterial and algal nutrition, phosphorus utilization, and phosphorus turnover times. The workshop concluded that SRP is an acceptable measure of dissolved bioavailable phosphorus when concentrations are significantly above detection limit, and recommended continuation of SRP measurements on surveillance cruises until a better alternative is developed.

Phosphorus Turnover in Soil and Its Uptake by Established Lolium perenne Plants

(1) A technique is described for measuring the time-course of uptake of 32p from soil by Lolium perenne plants. (2) Carrier-free 32p was applied to the soil and the 32p content of leaves was determined non-destructively every 1 or 2 days. When 32p uptake had almost ceased the plants were harvested and their total 32p content was determined. (3) Well-established plants took up 10-40% per day of the phosphorus in the soil labile pool. The transfer in the soil from labile to non-labile forms per day always exceeded this. (4) Since the amount of phosphorus in the labile pool cannot have been changing rapidly, phosphorus transfer from non-labile to labile and from labile to non-labile forms must have been going on simultaneously and rapidly. The half-time for phosphorus residence in the labile pool was about 1-2 days. (5) The method has potential for the further study of phosphorus turnover and uptake in pots and in the field.

Turnover of carbon, nitrogen and phosphorus through the microbial biomass in soils incubated with 14-C-, 15N- and 32P-labelled bacterial cells

A mixture of triply-labelled ( 14C, 15N, 32P) bacterial cells was added as a fresh suspension to two soils, a sandy-loam and a clay soil. The soils were incubated for up to 101 days under continuously moist conditions, or with periodic drying. Rates of mineralization of 14C, and especially of 15N and 32P, indicated rapid death and extensive decomposition of the added cells within a few days of incubation. Throughout, decomposition was more rapid in the sandy-loam soil than in the clay soil; and lower proportions of applied 14C, 15N and 32P were accounted for in the soil biota of the sandy-loam, as judged from assays of biomass 14C, 15N and 32P respectively. In general, the relative behaviour of the isotopes in the two soils with respect to their incorporation into biomass and subsequent net decay were similar to that found for soils in which 14C, 15N and 32P were added as soluble substrates and in which biomass and metabolites were formed in situ. The proportions of bacterial 14C released as 14CO 2 over 130 days were unaffected by the amounts added to soils, whereas the proportions of added 14C present as biomass 14C were slightly greater, the less added initially. Periodic drying of soils marginally decreased 14CO 2 evolution and increased 15N mineralization, accompanied by decreased recoveries of 15N in biomass. Differences in the behaviour of C and N in the two soils, and under different incubation conditions, have been described by a simulation model, which accommodates differences in the rates of turnover of microbial biomass C and N.

Correlation of a lake eutrophication model to field experiments

A vertical box interaction model is applied to a bay of the highly eutrophic Lake Lugano on the Italian-Swiss border, in order to interprete the experimental framework developed by sampling activity and field research during 1981. This bay receives the greatest part of the effluent put into Lake Lugano, after passing through a waste water treatment plant and being discharged into the bay through one of its tributaries. Particular attention is devoted to the phosphorus cycle in the epilimnion during summer stratification, and to the role played by the organic phosphorus components (dissolved and particulate) in the regeneration process. In fact the operation of the waste water treatment plant has increased the concentration significance of the organic dissolved phosphorus form in the bay, raising the problem of its biological availability. The procedure consists of assessing the transfer coefficients among the various phosphorus forms by means of comparisons between calculated evolution and measured average summer value of the related epilimnetic concentrations. The proposed correlation allows an evaluation of the mean residence time of phosphorus in the various compartments and the total phosphorus turnover time in the ecosystem. A predictive use of the model simulating a reduction of phosphorus loading is also presented.

Phosphorus in acidified lakes: The example of Lake G�rdsj�n, Sweden

Supply and turnover of phosphorus was studied in an acidified lake ecosystem, Lake Gardsjon, located in southwestern Sweden. This study included transport and budget calculations combined with field and laboratory experimental work on abiotic phosphorus chemistry and biological utilization of phosphorus. The main conclusions presented in this paper are: - The acidification process in inland waters resulting from acid atmospheric deposition is accompanied by ‘oligotrophication’ because of reduced input of phosphorus from the drainage area, possibly due to efficient fixation of phosphorus to aluminium complexes in the B-horizon of podzol soils - Primary productivity in acidified lakes is limited mainly by low phosphorus supply - Algal utilization of phosphorus in acidified lakes is impaired, yielding lower biomass than could be expected from ambient phosphorus concentrations. One possible reason for this could be that enzymatic recycling of organic phosphates is prevented by high levels of aluminium in lake water.

Box model analysis of hydrography and behaviour of nitrogen and phosphorus in a eutrophic estuary

In order to investigate the mechanism of eutrophication in Atsumi Bay which is a shallow and partially mixed estuary, distributions of temperature, salinity and concentrations of nitrogen and phosphorus in all their chemical forms were observed once a month throughout a year. Supplies of freshwater and nutrients are estimated and balances of salt and nutrients are examined using a modified box model. The deduced estuarine hydrography and calculated values of photosynthesis, decomposition, deposition and sedimentation are compared with those obtained byin situ observations and laboratory experiments. It is found that the factors responsible for the appearance of heavy eutrophication include not only the general increase of nutrient supply from land but also nutrient accumulation in the rainy season just before summer, the N/P ratio of the supply from land being favourable for uptake by phytoplankton, formation of semi-closed circulations of the nutrients associated with stratification and vertical circulation of estuarine water, and possibly the inorganic turnover of phosphorus (PO4-P) under aerobic and anaerobic conditions. The usefulness of the modified box model for obtaining a synoptic understanding of the estuarine system is also demonstrated.

Location of Phosphorus in Activated Sludge and Function of Intracellular Polyphosphates in Biological Phosphorus Removal Process

The STS method, a method for the fractionation of intracellular phosphorus, was introduced into the examination of the phosphorus location of activated sludges, and some basic aspects involved in the biological phosphorus removal process were investigated from biological points of view. Although both lowmolecular and highmolecular polyphosphates appeared in the sludges produced in the biological phosphorus removal process, the high phosphorus content of the sludges was caused mainly by the accumulation of lowmolecular polyphosphates and lowmolecular polyphosphates were principally responsible for the release and uptake of phosphorus. The turnover of phosphorus in lowmolecular and highmolecular polyphosphates was investigated by using 32P-labelled orthophosphate as a tracer. The phosphorus turnover in lowmolecular polyphosphates was not observed under both anaerobic and aerobic conditions, while the phosphorus turnover in highmolecular polyphosphates occurred under the aerobic conditions. It was indicated that lowmolecular polyphosphates function as the energy pool under the anaerobic conditions and that highmolecular polyphosphates function as the phosphorus source for the microbial growth.

Experimental lake fertilization: Turnover of nitrogen and phosphorus in stratified and non-stratified subarctic lakes in northern Sweden

Experimental lake fertilization: Turnover of nitrogen and phosphorus in stratified and non-stratified subarctic lakes in northern Sweden

Comparison of Phosphorus Turnover Times in Northern Manitoba Reservoirs with Lakes of the Experimental Lakes Area

The turnover time, τ, of [32P]PO4was measured during July and September in a natural lake and two lakes in northern Manitoba that were undergoing impoundment in 1976. The τ values were 10–1000 times longer than those observed in the epilimnia and hypolimnia of two lakes being experimentally enriched in northwestern Ontario (Experimental Lakes Area) in the same summer. Algal populations in the Experimental Lakes Area exhibited short τ values over a large range of temperature and light values, which exceeded the ranges of temperatures and light intensities measured in northern Manitoba. In northern Manitoba the shortest τ values occurred in July when an independent indicator of sestonic P deficiency, the particulate alkaline phosphatase activity per unit weight ATP, measured moderate to severe P deficiency. In September in northern Manitoba, τ values were at least 10 times greater than in July and were among the highest reported in the literature. The 2-yr-old Notigi Reservoir had the highest τ values in both July and September, and it deviated strongly from the expected chlorophyll–phosphorus relation for north temperate lakes. These new reservoirs in northern Manitoba are not P limited and even the natural lakes may be only moderately P limited.

The bioaccumulation factor for phosphorus-32 in edible fish tissue.

Information used to derive the bioaccumulation factor for 32P in edible portions of fish was reviewed to evaluate the currently recommended values of 100,000 in fresh water and 29,000 in sea water that are applied in calculating radiation doses to persons from nuclear-power reactor effluents. A generic phosphorus bioaccumulation factor of 70,000 was obtained for larger rivers and estuarine waters on the basis of geometric mean phosphorus concentrations of 2 mg/g wet weight in fish muscle and 0.03 mg/l dissolved in water. A 20-fold lower bioaccumulation factor was inferred for 32P because radioactive decay is much faster than phosphorus turnover. A phosphorus turnover rate in muscle of 0.2% per day was estimated as a long-term average for edible-size fish, although more rapid turnover has been observed for brief periods. Large deviations from the generic bioaccumulation factor will occur for different phosphorus concentrations in water and turnover rates in fish. Site-specific determinations are also needed because 32P is bioaccumulated at lower trophic levels in the food web, not in the fish. Hence, the availability of concentrating organisms determines the bioaccumulation factor. Several other conditions that affect the 32P bioaccumulation factor have not been quantified and are suggested for study.

クロマツ，スギ，ヒノキ，タケの各人工林でのりんとＢＨＣの分布と移動

筆者らは1983年2月から10月まで大分県臼杵市で,クロマツ,スギ,ヒノキ,タケ,の各人工林でリンとBHCの分布を調査した。比較として,同じ地域の自然林(針葉広葉混交林)と長野県燕岳山麓中房温泉のヒノキ林で同様の調査を行った。これらの結果を要約すると次のようになる。1) クロマツ,スギ,ヒノキの各林分でのリンの分布はほとんど同じ値を示したが,タケ林はこれに比べてリンの含量がやや少なかった。2) 各林分で,食物連鎖が進むに従って,リンの生物濃縮がみられた。3) 人工林と自然林でのリンの分布は人工林の土壌の含量が自然林のそれに比べてやや高く,自然林のアカネズミのリンの含量は人工林のそれよりやや高かった。4) BHCの分布はリンとまったく異なり,L層のBHCの含量が最も高く,ついで樹木類の葉のそれであった。樹木類の葉では針葉樹のBHCの含量が高く,その順位はヒノキ,スギ,クロマツと低くなり,タケに含まれるそれは著しく低かった。

Nutrient cycling within a 27-year-old Eucalyptus grandis plantation in New South Wales

A 27-year-old stand of flooded gum ( Eucalyptus grandis Hill ex Maiden) in the North Coast Region of N.S.W. was assessed in relation to aboveground distribution and turnover of organic matter, nitrogen, phosphorus, calcium, magnesium and potassium. Of the 453 t ha −1 of aboveground organic matter present, 394 t was in the tree, 42 t in the understorey and 28 t in the forest floor. The total nitrogen, phosphorus, calcium, magnesium and potassium contents of the stand were 739, 44, 1254 and 658 kg ha −1, respectively, and the understorey contained 35%, 35%, 16%, 24% and 49% of the above-ground distribution of these nutrients respectively. Although the developing rainforest understorey comprised a relatively small portion (9.3%) of the total aboveground biomass, it played a disproportionate role in nutrient accumulation and uptake, and had an annual net accumulation of 14%, 55%, 59%, 30%, 44% and 69% of the aboveground organic matter, nitrogen, phosphorus, calcium, magnesium and potassium respectively. The net annual removal from the soil was 30, 1, 38, 5 and 31 kg ha −1 year −1 for nitrogen, phosphorus, calcium, magnesium and potassium, respectively. Flooded gum had very high accumulations of calcium in the bark and the effect of this in nutrient cycling is discussed. An idealised management system, to exploit and optimise the nutrient cycle of flooded gum, has been hypothesided.

Studies of Central Australian Semidesert Rangelands. II. Range Condition and the Nutrient Dynamics of the Herbage Layer, Litter and Soil.

The levels and turnover of nitrogen, phosphorus and sulfur in the herbage layer: litter and soil of three central Australian plant communities were investigated, following several years of above-average rainfall, and the possibility of a relationship between nutrient levels and range condition assessment was examined. There were only a few positive correlations between range condition and phosphorus levels, and they were not associated with the susceptibility of different soils to erosional losses. There were no positive correlations between range condition and the levels of either nitrogen or sulfur. The herbage and litter layers together, of the three plant communities, contained 30-72 kg ha-1 of total nitrogen, 4 kg ha-1 of total phosphorus and 4-7 kg ha-1 of total sulfur. These quantities were comparable to those of arid regions in other parts of the world, but the levels of nitrogen, phosphorus and sulfur in soils, estimated by incubation or extraction to be available to plants, were comparatively low. Incubated nitrogen in the 0-10 cm depth of soils was 9-14 ppm and extractable phosphorus was 3-1 1 ppm. The 0-4 cm depth of soil contained 0.5-3 ppm extractable sulfur, and concentrations decreased with depth. Total soil nitrogen was lower than that in other arid regions whereas the amount of organic carbon in soil was comparable, so that C:N was relatively high. Substantial withdrawal of nutrients from senescing plant parts and rapid cycling of nutrients through litter appeared to be responsible for maintaining the level of nutrients in the herbage layer.