The determination of exchangeable cations in acid soils: Errors caused by weathering reactions during neutral salt extraction

1991 ◽  
Vol 71 (2) ◽  
pp. 155-163 ◽  
Author(s):  
Pat E. Rasmussen ◽  
Sherry L. Schiff ◽  
H. Wayne Nesbitt
Keyword(s):  
Acid Soils ◽  
Exchangeable Cations ◽  
Neutral Salt ◽  
Salt Extraction ◽  
Exchangeable Acidity ◽  
Aluminum Hydroxides ◽  
Exchangeable Al ◽  
Acid Forest Soils ◽  
Series Of Experiments

To investigate pH-controlled chemical reactions associated with the neutral salt measurement of exchangeable cations in acid soils, and to estimate the potential error caused by such reactions, a series of experiments was performed which modify an established BaCl2 extraction method. Results showed that dissolution of amorphous silica, aluminum hydroxides and organic material occurs during neutral salt extraction, contributing cations to solution which are indistinguishable from exchangeable cations. As a result overestimates of exchangeable Al and Ca occur, but the error is not significant (> 10%) except in certain Ae horizons which are low in total CEC and high in exchangeable acidity. The 2-h BaCl2 method is recommended over the 4-hour NaCl method to minimize interference from weathering reactions. Key words: Cation exchange, exchangeable acidity, Al, H, acid forest soils, weathering

An examination of some acid soils at Batlow, New-South-Wales

Soil Research ◽  
1993 ◽  
Vol 31 (4) ◽  
pp. 437 ◽  
Author(s):  
IP Little
Keyword(s):  
Acid Soils ◽  
Principal Component ◽  
Apple Fruit ◽  
Exchange Capacity ◽  
Soil Survey ◽  
South Wales ◽  
Exchangeable Ca ◽  
Exchangeable Al ◽  
Clay Suspensions

This paper has two components. Firstly it evaluates a set of data for the apple-growing soils of the Batlow district. Secondly it makes some comments on the use of silver thiourea for the determination of exchangeable Al and Mn and the estimation of exchangeable Al by titration of 1 M KCl suspensions. A group of 21 profiles from soils used for apple-growing in the Batlow District were examined in the laboratory. It was found that many of the soils were very acidic, especially in the subsoil. Dilute CaCl2 extracted as much as 50 �g g-1 of Al and considerable exchangeable Al was extracted by silver thiourea. Exchangeable Ca levels were usually adequate for plant growth, hence low levels in apple fruit may reflect the adverse effect of Al on Ca uptake by the plant. Potassium levels were low and may be marginal in some cases and Mg tended to be low in the surface. Principal component analysis showed 77% of the variation in the data was accounted for by three independent components, one involving pH, exchangeable Ca and Al, one involving K and Mg and one involving exchangeable Mn. It was demonstrated that silver thiourea does not replace Al as effectively as the basic exchangeable cations. Also, thiourea reduces Mn so that low values will be obtained for exchangeable Al in soils with much easily reducible Mn because of the increase in pH that accompanies reduction. Silver thiourea appears to overestimate exchangeable Al in some soils with very low cation exchange capacity. Titration of clay suspensions in 1 M KCl is a satisfactory and reliable way of measuring exchangeable Al that also enables an assessment of pH-dependent charge. The method used by the USDA Soil Survey Staff, viz. equilibration of soil samples with 1 M KCl for 16 h, filtration, and determination of Al also gives reproducible results and is taken as the standard. Successive leaching with portions of 1 M KCl tends to give low values for exchangeable Al.

The Effect of Stress and Warfarin on the Adrenal Gland in Relation to Spontaneous Hemorrhage, as Judged by Measurement of Adrenal Ascorbic Acid and Serum Corticosterone

1971 ◽  
Vol 26 (02) ◽  
pp. 275-288 ◽  
Author(s):  
S Chattopadhyay ◽  
D. D Johnson ◽  
G. J Millar ◽  
L. B Jaques
Keyword(s):  
Ascorbic Acid ◽  
Acid Concentration ◽  
Ascorbic Acid Concentration ◽  
Corticosterone Concentration ◽  
Serum Corticosterone ◽  
Spontaneous Hemorrhage ◽  
Combined Action ◽  
Series Of Experiments ◽  
Pituitary Adrenal Axis

SummaryRats were subjected to the following procedures: No treatment, Stressor (10% NaCl i.p.), Warfarin for 7 days, Stressor followed by Warfarin; and groups were sacrificed at intervals for assessment of spontaneous hemorrhage and of adrenal ascorbic acid concentration. There was no hemorrhage in the no treatment and stressor groups; some hemorrhage in the warfarin group; profound hemorrhage with Warfarin + Stressor. The adrenal ascorbic acid concentration was found to be lower, 8 h and again 5 days after stress, and remained lower in the warfarin + stress animals. Warfarin had no effect on adrenal ascorbic acid level.In another series of experiments in which the stress consisted of an electric current to the cage floor for 6 sec over 15 min, rats were sacrificed daily for determination of serum corticosterone concentration and occurrence of spontaneous hemorrhage. There was a statistically significant increase of serum corticosterone concentration with stress, warfarin and combined warfarin and stress treatments (P< 0.001 for all three variables). There was a significant correlation (r = 0.96 and 0.89, P< 0.01) for serum corticosterone concentration with hemorrhage score and incidence of hemorrhage in stressed rats receiving warfarin, but not in those receiving only warfarin. The results indicate an activation, rather than an exhaustion, of the pituitary-adrenal axis during the combined action of anticoagulant and stress, which results in the development of spontaneous hemorrhage.

W. T. Astbury and Ross G. Harrison: the search for the molecular determination of form in the developing embryo

1980 ◽  
Vol 35 (2) ◽  
pp. 195-219 ◽  
Keyword(s):  
Royal Society ◽  
Limb Bud ◽  
Amphibian Embryo ◽  
X Ray ◽  
Biological Phenomena ◽  
Biology I ◽  
Series Of Experiments ◽  
Molecular Patterns ◽  
Molecular Determination

Amongst the Fellows elected to the Royal Society in 1941 were W. T. Astbury for his studies using X-ray analysis to study the structures of natural fibres, and amongst the Foreign Members elected that year was Ross G. Harrison for his contributions to embryology. Astbury and Harrison were very different in temperament, and worked in very different fields on either side of the Atlantic, yet they were united in their approach to the study of biological phenomena. Both Astbury and Harrison believed that the organization and form of biological materials whether wool fibres or the limb-bud in an amphibian embryo depended on molecular structure and pattern. Moreover both were concerned with dynamic aspects of form; Astbury’s greatest achievement was to demonstrate the dynamic, reversible folding and stretching of proteins in the k-m-e-f group, and Harrison looked to changing molecular patterns to account for changing symmetries in the developing embryo. It was this common approach that brought them together and led to Harrison spending a brief month in Leeds where they and K. M. Rudall performed what have been described as ‘truly progressive experiments in molecular biology’. I believe this short series of experiments illuminates the character and work of both Harrison and Astbury and illustrates the difficulties, practical and conceptual, in carrying out ‘progressive experiments’. I shall begin by reviewing briefly the embryological background of the time before going on to discuss in detail the approaches of Harrison and Astbury to their work and the outcome of their collaboration.

Rapidly extracted (0.02 M CaCl2-soluble) reactive aluminum as a measure of aluminum toxicity in soils

Soil Research ◽  
1989 ◽  
Vol 27 (4) ◽  
pp. 663 ◽  
Author(s):  
EA Close ◽  
HKJ Powell
Keyword(s):  
Salicylic Acid ◽  
White Clover ◽  
Aluminum Toxicity ◽  
Maximum Yield ◽  
Acid Soils ◽  
Aluminium Toxicity ◽  
Field Method ◽  
Colorimetric Analysis ◽  
Aluminium Species

This paper examines the use of short extraction times, and the determination of aluminium with chrome azurol S (CAS), for the estimation of 0.02 M CaCl2-soluble aluminium in soils. It reports the correlation between CAS-reactive aluminium in 5 min extracts and percent maximum yield of white clover (Trifolium repens) for a series of acid soils. The reactivity of soluble and colloidal aluminium species with the metallochromic reagent CAS has been assessed. ~ l ( a q ) ~ + , simple hydroxy species and complexes of weakly binding ligands (salicylic acid, tannins) are CAS-reactive (2 rnin). In contrast, complexes of strongly binding ligands (citric acid, fulvic acid) are not CAS-reactive ([Al] ~ [L] ~ [CAS] ~ 1-2~10-5 M). For a series of six limed phosphated topsoils and subsoils (pH 4.2-5.5), 0.02 M CaCl2- soluble aluminium, as determined with CAS, was negatively correlated against the percent maximum yield of white clover; r2 = -0.73** (5 min extraction), n = 20. This correlation is similar to that for yield against total aluminium as determined by atomic absorption spectroscopy after 60 min extraction (r2 = -0.77**). However, the colorimetric analysis is more convenient and sensitive; further, it does not measure colloidal and polymeric aluminium species (which may not be plant-available). The satisfactory correlation achieved for short extraction times suggests use of CAS for a rapid field method for aluminium toxicity in soils.

IV. On the determination of the scale value of a Thomson’s quadrant electrometer used for registering the variations in atmospheric electricity at the Kew Observatory

1878 ◽  
Vol 27 (185-189) ◽  
pp. 356-361 ◽  
Keyword(s):  
Atmospheric Electricity ◽  
Series Of Experiments

The Meteorological Council, being desirous of discussing the photographic traces produced by their electrograph at the Kew Observatory some time since, requested the Kew Committee to institute a series of experiments, with the view of determining the scale value of the instrument, in order to prepare a suitable scale for measuring the curves. The Kew Committee, at their meeting in November, entrusted the matter to me, and accordingly, having obtained the loan of a battery of 300 Bunsen cells, some preliminary experiments were made, which showed that the greatest potential which could be obtained with them was very inadequate for the purpose.

A New Approach for Erosion Prediction Due To Fly Ash

1981 ◽  
Vol 103 (2) ◽  
pp. 265-270 ◽  
Author(s):  
R. Kotwal ◽  
W. Tabakoff
Keyword(s):  
Fly Ash ◽  
Gas Turbines ◽  
Precise Determination ◽  
Erosion Prediction ◽  
Industrial Gas Turbines ◽  
Series Of Experiments ◽  
A New Technique ◽  
Nickel Base ◽  
Semi Empirical

With increasing interest in the burning of coal in industrial gas turbines, there is also concern for the precise determination of the erosive effects on the turbine components. Series of experiments were conducted to determine the effects of fly ash constituents, particle size, particle velocity, angle of attack and target temperature on the erosion of iron and nickel base alloys. Based on the experimental results, a semi-empirical equation has been obtained for the prediction of the erosion losses. This equation provides a new technique for predicting the metal erosion due to the fly ash produced by the conventional burning of coal.

Further observations of enhanced lines

1897 ◽  
Vol 61 (369-377) ◽  
pp. 441-444 ◽  
Keyword(s):  
High Temperature ◽  
Solar Chromosphere ◽  
Stellar Spectra ◽  
Series Of Experiments

In a recent paper I gave an account of a series of experiments having for their object the determination of the lines which were enhanced in the spectra of iron, magnesium, and calcium, on passing from the arc to a high temperature spark, and I pointed out the presence of these lines in the spectra of the hotter stars and in the solar chromosphere. The spectra of the following additional elements have since been investigated in a similar manner, and the enhanced lines have been tabulated and compared with chromospheric and stellar spectra.

scholarly journals An attempt to determine the adiabatic relations of ethyl oxide

1897 ◽  
Vol 60 (359-367) ◽  
pp. 336-337 ◽  
Keyword(s):  
Wave Length ◽  
Experimental Results ◽  
Mathematical Discussion ◽  
Series Of Experiments

The wave-length of sound in gaseous and in liquid ethyl oxide (sulphuric ether) has been determined by the two first-mentioned of the authors, by means of Kundt’s method, between limits of temperature ranging from 100° C. to 200° C., and of pressure ranging from 4000 mm. to 31,000 mm. of mercury, and of volume ranging from 2·6 c. c, per gram to 71 c. c. per gram. Making use of the same apparatus throughout, the results obtained are to be regarded as comparative, and, by careful determination of the pitch of the tone transmitted through the gas, it is probable they are approximately absolute. The sections of the complete memoir deal with (I) a description of the apparatus employed, (II) the method of ascertaining the weights of ether used in each series of experiments, (III) determinations of the frequency of the vibrating rod, (IV) the calculations of the adiabatic elasticity and tables of the experimental results, and (V) a mathematical discussion of the results. The last section is due to Mr. Rose-Innes.

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