scholarly journals Fate of low-molecular-weight organic phosphorus compounds in the P-rich and P-poor paddy soils

2021 ◽  
Vol 20 (9) ◽  
pp. 2526-2534
Author(s):  
Bao-zhen LI ◽  
Anna GUNINA ◽  
Mostafa ZHRAN ◽  
L. JONES Davey ◽  
W. HILL Paul ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Organic Phosphorus ◽  
Paddy Soils ◽  
Phosphorus Compounds ◽  
Low Molecular Weight

Movements of Phosphorus Between its Biologically Important Forms in Lake Water

1973 ◽  
Vol 30 (10) ◽  
pp. 1525-1536 ◽  
Author(s):  
D. R. S. Lean
Keyword(s):  
Molecular Weight ◽  
Lake Water ◽  
Membrane Filtration ◽  
Organic Phosphorus ◽  
Gel Filtration ◽  
Particulate Fraction ◽  
Low Molecular Weight ◽  
Radioactive Phosphorus ◽  
Dissolved Phosphorus ◽  
Kinetics Of

A model consistent with the kinetics of phosphorus in epilimnetic lake water was developed. Adding 32PO4 to lake water and separating the major forms of dissolved phosphorus by Sephadex gel filtration showed that the exchange mechanism between inorganic phosphate and the particulate fraction predominates. At the same time, a low-molecular-weight phosphorus compound is excreted which combines with colloids in lake water, releasing phosphate from the colloid and making the phosphate available for "transfer" again. This rapid cycling of phosphorus between the four principal forms — the particulate fraction, the low-molecular-weight P compound, colloidal P, and phosphate — appears to contribute to formation of colloids in lake water. No direct complexing of phosphate to the colloid was observed. Only in the presence of algae, bacteria, and other particulate matter did the radioactive phosphorus move to the low-molecular weight and the colloidal forms. The low-molecular-weight compound is negatively charged, as is the colloidal P, but to a lesser degree. Both are removed by anion exchange materials along with phosphate, but the rate that they move into the fraction removed by membrane filtration is different from that for phosphate. When filtrate is refiltered a large amount of the colloidal P is retained by the filter. This complicates measurements of transfer and makes previous studies on utilization of dissolved organic phosphorus of doubtful value since corrections for filter retention were rarely, if ever, made.

Dissolved organic and inorganic phosphorus compounds in pig slurry: effect of drying

1978 ◽  
Vol 90 (1) ◽  
pp. 39-45 ◽  
Author(s):  
R. G. Gerritse ◽  
R. Eksteen
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Organic Molecules ◽  
Organic Phosphorus ◽  
Alkali Treatment ◽  
Gel Filtration ◽  
Inorganic Phosphorus ◽  
Phosphorus Compounds ◽  
Pig Slurry ◽  
Acid And Alkali Treatment

SUMMARYFrom gel filtration studies it has been found that more than 50% of organic phosphorus dissolved in pig slurry is contained in compounds of high molecular weight. Various ions, e.g. calcium, copper, orthophosphate, are bound by these compounds. From the purine and pyrimidine base composition and resistance to acid and alkali treatment it follows that these organic compounds probably are complexes derived from polydeoxyribonucleotides (DNA).The effect of drying pig slurry at various temperatures (0–100 °C) on the solubility of phosphorus, calcium and copper after redispersion of the dried slurry was investigated. The solubility of organic phosphorus was not affected by drying and redispersion in water, but the amount of phosphorus contained in dissolved organic molecules of high molecular weight decreased on drying at higher temperatures. The solubility of copper was also not affected by heat treatment. The solubility of inorganic phosphorus is mainly related to the solubility constants of mineral phosphates. On the other hand the total solubility of the cations involved is determined by complex formation.

31P FT-NMR of Concentrated Lake Water Samples

1997 ◽  
Author(s):  
Mark A. Nanny ◽  
Roger A. Minear
Keyword(s):  
Molecular Weight ◽  
Nmr Spectroscopy ◽  
Reverse Osmosis ◽  
Lake Water ◽  
Organic Phosphorus ◽  
Phosphorus Compounds ◽  
Lanthanum Hydroxide ◽  
Processing Times ◽  
Concentration Method ◽  
Broad Signal

The use of phosphorus-31 Fourier Transform nuclear magnetic resonance (31P FT-NMR) spectroscopy for the study of dissolved organic phosphorus (DOP) in fresh water has been recently established by Nanny and Minear. The fact that NMR is an element-specific technique, is nondestructive, and has the ability to differentiate between similar phosphorus compounds makes it invaluable for the identification and characterization of DOP. Such information regarding DOP is required in order to understand aquatic nutrient cycling. The difficulty with using 31P FT-NMR spectroscopy for such studies is the extremely low DOP concentration; usually ranging from < 1 μg P/L in oligotrophic lakes to approximately 100 μg P/L for eutrophic systems. Nanny and Minear raised the DOP concentration into the NMR detection range, which is on the order of milligrams of phosphorus/liter, by concentrating large volumes of lake water with ultrafiltration (UF) and reverse osmosis (RO) membranes. Volume concentration factors of several ten thousand fold provided DOP concentrations of up to 60 mg P/L. Other DOP concentration methods such as anion exchange, lanthanum hydroxide precipitation, and lyophilization require severe chemical and/or physical transformations of the sample and/or they need long processing times, all of which increase the risk of DOP hydrolysis. Sample concentration with UF and RO membranes does not require the sample to undergo these major changes and is also a relatively rapid concentration method. In addition to these concentration capabilities, the use of ultrafiltration and reverse osmosis membranes permitted fractionation of the DOP samples according to molecular size. Nanny and Minear used three membranes in series with decreasing pore size: 30kDa (kilodaltons), 1 kDa, and RO (95% NaCl rejection) to separate the high-molecular-weight, intermediate-molecular-weight, and low-molecular-weight DOP species. In the intermediate-molecular-weight fraction, Nanny and Minear observed the presence of monoester and diester phosphates. Spectra from ten samples collected over a year typically consisted of a large broad signal in the monoester phosphate region spanning from a chemical shift of 2.00 ppm to −0.50 ppm. The maximum of this signal was usually in the range of 1.00 to 1.50 ppm. This broad signal had a shoulder in the diester phosphate region which sometimes was intense enough to appear as an individual signal.

scholarly journals An in-depth assessment into simultaneous monitoring of dissolved reactive phosphorus (DRP) and low-molecular-weight organic phosphorus (LMWOP) in aquatic environments using diffusive gradients in thin films (DGT)

2015 ◽  
Vol 17 (4) ◽  
pp. 711-727 ◽  
Author(s):  
Christian Wilhelm Mohr ◽  
Rolf David Vogt ◽  
Oddvar Røyset ◽  
Tom Andersen ◽  
Neha Amit Parekh
Keyword(s):  
Molecular Weight ◽  
Organic Phosphorus ◽  
Aquatic Environments ◽  
Low Molecular Weight ◽  
P Fractionation ◽  
Physiochemical Properties ◽  
Dissolved Reactive Phosphorus ◽  
Reactive Phosphorus ◽  
Diffusive Gradients

In situP fractionation size distribution is altered during uptake by the DGT due to the size and physiochemical properties of the molecular species.

Orthophosphate and its Flux in Lake Waters

1981 ◽  
Vol 38 (10) ◽  
pp. 1215-1219 ◽  
Author(s):  
E. White ◽  
G. Payne ◽  
S. Pickmere ◽  
F. R. Pick
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Organic Phosphorus ◽  
Particulate Material ◽  
Major Influence ◽  
Low Molecular Weight ◽  
Gel Chromatography ◽  
Near Surface ◽  
Molybdenum Blue ◽  
Dominant Component

Molybdate reactive high molecular weight (MW > 5000) phosphorus (RHMW-P) in solution was separated from low molecular weight material (PO4-P) by Sephadex gel (G25–150). PO4-P is as close to orthophosphate as has been possible to achieve with molybdenum blue technology. Chromatograms of near-surface waters of 32 lakes showed that RHMW-P was rarely the dominant component of dissolved reactive phosphorus (DRP), and so cannot be the major influence causing discrepant estimates of orthophosphate concentrations derived from molybdenum blue and radiotracer technology. The low molecular weight material (PO4-P) may still contain chemically reactive organic phosphorus which could lead to overestimation of orthophosphate. Recent literature points to discrepancies in radiotracer estimates too, so further effort is required to provide reliable assessment of orthophosphate in lake water. Estimates of orthophosphate flux from solution to particulate material based on 32PO4-derived turnover times are likely to be in error irrespective of the source of orthophosphate estimate.Key words: molybdenum blue method, radiotracer, orthophosphate flux, reactive high molecular weight phosphorus, gel chromatography, radiobioassay

A high-performance oil-free backing pump for electron microscopes

1978 ◽  
Vol 36 (1) ◽  
pp. 110-111
Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Hot Spots ◽  
High Performance ◽  
Carbonaceous Material ◽  
Contamination Rate ◽  
Low Molecular Weight ◽  
Principal Source ◽  
Rotary Pumps ◽  
Electron Microscopes

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.

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