Phosphorus extraction

Method 65, p. 158. Bicarbonate extractable phosphorus extractable in soil Method 76, p. 183. Sulphur, sulphate in soil... 

Kuo, R.J. Matijevic, E. (1980) Particle adhesion and removal in model systems. III. Monodisperse ferric oxide on steel. J. Colloid Interface Sci. 78 407-421 Kuo, S. Jellum, E.J. (1994) The effect of soil phosphorus buffering capacity on phosphorus extraction by iron oxide-coated paper strips in some acid soils. Soil Sci. 158 124-131... 

Method 6.2a. Determination of water-soiubie phosphorus (extraction)... 

It is recommended that the compound be fused with a mixture of sodium carbonate (2 parts) and sodium peroxide (1 part) as in the test for Phosphorus. Extract the fused mass with water, filter, and acidify with dilute hydrochloric acid. Pass hydrogen sulphide through the hot solution arsenic is precipitated as yellow arsenic sulphide. If antimony is present, it will be precipitated as orange antimony trisulphide. 

Figure 10 The extraction of uranyl nitrate U02(N03)2, from 1 M nitric acid by a number of different phosphorus extractants...

Extraction of soils for analysis of die readily available nutrients include replacement of exchangeable cations by salt solutions, dilute acids, and dilute alkalies such as NaHCCh. Fluoride solutions ate employed to repress iron, aluminum, and calcium activity during the extraction of phosphorus. Extraction of the soil solution is effected by displacement in a soil column, often through the application of pressure across a pressure membrane. The soil solution is analyzed by conductance and elemental analysis methods. Also, the total elemental analysis of soils is made by Na2CC>3 fusion of the soil followed by classical geochemical analysis methods. 

Naik, P.W. Dhami, P.S. Misra, S.K. Jambunathan, U. Mathur, J.N. Use of organo-phosphorus extractants impregnated on silica gel for the extraction chromatographic separation of minor actinides from high level waste solutions, J. Radioanal. Nucl. Chem. 257 (2003) 327-332. 

Kedari et al. (101) studied the influence of adding a modifier on a solvent extraction with an Ir(IV)-Cyanex 923 system. Cyanex 923 is a commercial neutral organo-phosphorus extractant widely used for extraction of metal ions or inorganic acids. They observed that decanol is not efficient as a modifier probably because of an interaction with Cyanex 923. TBP can only be used at 4 M HC1 otherwise the efficiency is poor. This highlights the fact that the interaction of the modifier with the extractant can modify the efficiency of the extraction. 

Water (elemental phosphorus) Extract with organic solvent oxidize to phosphate Spectrophotometric 1.5 pg/L No data Zitko et al. 1970 Idler et al. 1981... 

Waste water (elemental phosphorus) Extract with organic solvent, oxidize to phosphate and back-extract in water Neutron activation analysis 0.01 pg/L 90-110 Lai and Rosenblatt 1977b... 

Soil and sediment (elemental phosphorus) Extract with isooctane Capillary Column GC-NPD 0.88 pg/kg 97.2 Walsh and Taylor 1992 Racine et al. 1993... 

Water (elemental phosphorus) Extract with isooctane or diethyl ether GC-NPD 0.011 pg/L 107 12 Walsh 1995... 

Phosphorus extracted from sediment by NaOH has been related to non-occluded, surface-exchangeable, bioavailable forms (22). Hydrochloric acid extraction yields occluded phosphorus incorporated in hydrous metal oxides, carbonate and phosphate minerals of sediment. Hydroxylamine reagent specifically removes hydrous manganese oxides, while amorphous hydrous oxides of iron and aluminijm are removed by the oxalate reagent. Total available sediment phosphorus analyses includes sediment organic phosphorus components in addition to the inorganic portion determined by the selective extraction procedures. 

In the lower reaches of the Genesee River, the results of the extractions suggest that substances other than hydrous oxides are phosphorus sinks. This is evident where the amount of sediment phosphorus extracted by hydrochloric acid steadily increases down river, while the oxalate extractable phosphorus remains relatively constant. Schwertmann (2 ) emphasized that the results of such procedures are best considered as a measure of the relative amount of a phase or, more generally, a measure of an element s reactivity in a sediment under carefully controlled conditions. Laboratory experiments (Figure 8) show that phosphorus uptake by calcium carbonate, under simulated natural conditions, proceeds slowly. The large hydrochloric acid extractable component observed at Rochester may arise from slow uptake and subsequent mineralization of dissolved inorganic phosphorus by carbonate minerals. 

Sediment phosphorus extraction analyses show that hydrous iron oxides (extracted by (NH4)2C204) play a major role in the transport of sediment phosphorus. In northern areas of the Genesee River watershed calcium carbonate formation also appears to be Involved in phosphorus fixation. Ion activity product calculations for water column samples from the Genesee River consistently exhibit subsaturation with respect to the stable calcium phosphate phase, hydroxyapatite. Calcium carbonate, which can serve as a substrate for phosphate mineralization, shows an ion activity product below the solubility product in the Genesee River except during the summer low-rainfall season. 

The dry-ashing plus acid digestion of tea leaves (Section 1.1) and the available phosphorus extraction (Section 1.3) are contrasting procedures in regard to the acceptable precision of the determination. In one the sample is weighed to 0.1 mg ( 0.02%), whereas in the other the 5 cm3 scoop used for measuring soil, may introduce a variation of 0.2 g ( 4%). You may like to think about this. Is the sample measuring procedure appropriate for the purpose of the analysis in each case ... 

The method involves initial leaching of the soil with a solution of barium chloride-triethanolamine buffered at pH 8.1, followed by calcium saturation. The Ca-saturated soil is equilibrated with standard phosphoric acid solution and the quantity of phosphorus adsorbed is evaluated. From this adsorbed phosphorus plus phosphorus extracted initially the AEG of the soil is calculated using the formula. 

Williams, E.C. and Saunders, W.M.H. (1956b) Significance of particle-size fractions in readily soluble phosphorus extractions by the acetic, Truog, and lactate methods, youma/ of Soil Science 7, 189-202. 

Methods used to quantify microbial phosphorus have so far been based on fumigation and extraction. The basic methods were published early in the 1980s (Brookes et al., 1982 Hedley and Stewart, 1982) and, of the methods presented in Table 7.2, that of Brookes et al. (1982) has been used the most frequently. Phosphorus released by fumigation is calculated as the difference between inorganic or total phosphorus extracted from fumigated and non-fumigated soil. Most phosphorus in microbial cells is... 

Table 7.3. Experimental factors K to convert phosphate or total phosphorus extracted after biocide treatment of soils into the total amount of phosphorus held in the soil microbial biomass. The factors were obtained from the recovery of bacterial and fungal cells added to the soils prior to fumigation and extraction. 

All values present microbial phosphorus extracted after soil fumigation (i.e. no conversion factor (KJ applied). See Table 7.2. 

It is evident from a number of studies that organic phosphorus may also accumulate in the root zone of plants. Increases in organic phosphorus extractable by sodium hydroxide (Saleque and Kirk, 1995 Zoysa et al., 1997, 1999 George et al, 2000a) and sodium bicarbonate (Helal and Sauerbeck, 1984 Ghen et al., 2002) have been reported and are gener-... 

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