Accumulation of sodium in soil is a serious problem in arid and semi-arid regions of the world. Millions of acres of once fertile land have been thrown out of cultivation and-millions more are being added every year. The magnitude of the problem can be visualized from the fact that in Alberta alone 10 million acres are either seriously or partially affected by excess salinity and/or exchangeable sodium. In West Pakistan 100,000 acres go out of cultivation annually because of this menace and in the United States, out of 300 million acres under irrigation, between 25 and 30 percent are affected to varying degrees. [...]

Literature was reviewed on zinc fractionation and factors affecting the availability of zinc to plants. An experiment was conducted to study the effect of liming on zinc fractions in soils. Liming decreased exchangeable zinc. However, no definite trend was observed in the other zinc fractions with increasing soil pH. An understanding of the distribution of zinc among various fractions in soils is important to understanding its soil chemistry. An experiment was further conducted to study the effect of liming and types of anion on the quantity-intensity relationships of zinc in soils. It was found that for all the soils, at the same level of added zinc, adsorption increased with increasing lime rates. Zinc adsorption isotherms with NO<SUB>3<SUP>-</SUB></SUP> and C1<SUP>-</SUP> as counter ions have smoother curves than with SO<SUB>4<SUP>2-</SUB></SUP> and H<SUB>2</SUB>PO<SUB>4<SUP>-</SUB></SUP>. The adsorption was highest with NO<SUB>3<SUP>-</SUB></SUP> and lowest with H<SUB>2</SUB>PO<SUB>4<SUP>-</SUB></SUP> as the background anion. Quantity and intensity factors influence the availability of nutrients in soils to plants. These factors describe what is referred to as the `labile pool'. Understanding of zinc labile pool is enhanced by radio isotope usage. Hence, an experiment was conducted to study the effect of liming on zinc labile pool as measured by the uptake of ryegrass utilizing the radioactive isotope of zinc. For both two harvests of perennial ryegrass there was a decrease in shoot zinc concentrtion and uptake with increasing lime rates. Higher zinc concentration was found in the soils with zinc-65 than without zinc-65. No definite trend was however observed in zinc labile pool with increasing lime rates. Several forms of zinc fertilizer are available for correcting zinc deficiency in soil. Variation in the ability of plants to absorb and utilize the different forms of zinc have been observed by many researchers. An experiment was conducted to study the effect of liming and types of complexing agent on the chemical composition of winter wheat grown on two soils of varying texture. The zinc forms differed significantly at the lime rate zero in relation to foliar zinc concentration. A decrease in shoot zinc concentration and uptake was observed with increasing lime rate. A similar trend was observed for one soil in relation to phosphorus concentration, except at the highest lime rate, where it remained fairly constant. There was however, an increase in shoot calcium concentration and uptake with increasing lime rate.

Sequential chemical extraction to fractionate metals in soils and sediments into different groups reflecting their &quot;leachability&quot; has been widely employed to determine distribution of metals in different physico-chemical phases. A large number of sequential extraction schemes have been reported, most of them modifications of Tessier's extraction protocol. Although this method has been widely accepted, it is important to highlight that sequential extraction procedures are often tedious and time consuming and that they also suffer from a number of limitations, such as the problem of achieving selective dissolution and the re-adsorption of trace metals during extraction. The objective of this study was to develop, optimise, characterise and apply a novel sequential extraction procedure for the evaluation of trace metal distribution in soils and sediments in order to speed up the process, but more importantly to provide robust data for further aid the chemical characterisation of such samples. The method developed used centrifugation to pass the extractant solution (HNO3) at increasing concentrations, through the soil/sediment sample. The sequential leachates were collected and analysed by ICP-AES for a suite of 18 analytes. The method then utilised chemometrics in order to facilitate processing of the data. Optimisation of the new extraction protocol was performed using an experimental design approach. This was important since the method employed multi-elemental analysis to predict the composition of the physico-chemical phases in a range of soils and sediments. The approach used for data processing was again novel and was based on a simple product of matrices. However many statistical and chemometric approaches are used throughout this thesis to aid both the design of the method and the interpretation of the data obtained. Once optimised, the methodology was evaluated using a range of reference materials and tentative assignments were made in order to characterise the different physico-chemical phases in the soils by comparison with previously obtained data following Tessier's protocol. Significant correlation was obtained for the exchangeable fraction, the fraction associated with carbonates and the iron and manganese oxides fraction. Hence the method proved to be effective in providing Important information in terms of metal distribution in agreement with established procedures. The method was then applied to the study of the effect of humic acids (HA) on trace metal distribution in two different samples. Both samples were spiked with increasing amounts of humic acids and the sequential extraction procedure was used to monitor the changes in metal distribution. Differences when HA were added were found for most of the physico-chemical components in both samples. This provided practical data to support the theoretical assumption that HA interact with the metals present in the soil samples changing their distribution. Using the new method, an evaluation of the trace metal distribution within the Arosa estuary (N.W. Spain) with respect to trace metal contamination was performed. Finally, an on-line automated multisequential extraction system was built &quot;in-house&quot;, and coupled with the ICP-AES instrument to allow the fast characterisation of soils and sediment samples. The new system proved to be faster than the batch method and minimised the chance of sample mislabelling, sample contamination etc. Good agreement between results obtained from the on-line method, the batch method, and results using the Tessier scheme was obtained. The automated method clearly offers great potential for a range of environmental pollution studies aiding the quick identication of the physico-chemical components in geochemical samples.

No description available.

Thesis (D.Sc.1979) -- University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1979.

Thesis (M.Sc.) --University of Adelaide, 1953? / Typewritten copy.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1960. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin, 1971. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

A very reliable method for the total analysis of the ammonium acetate leachate has been outlined. This is both simple and straight forward and is more rapid than any which have been seen in the literature. It is particularly applicable where a worker must perform a large number of routine analyses in the minimum of time. Shirley (29) and other workers have shown that 1000 ml. of leaching solution is generally necessary to extract all the exchangeable gases. The present investigation has shown that the time of leaching makes no appreciable difference to the amounts of bases replaced, as long as this exceeds four hours. Two alternative methods have been introduced for the rapid determination of the total exchangeable bases in a soil and there are considered to be more reliable than that of Bray and White. It is suggested that the two new methods might yield a still greater degree of accuracy if larger aliquots were to be used for each determination. It is further pointed out that the values obtained by the chloride methods are more likely to represent correct values than the sum totals of the bases as determined individually, since these are arrived at by summing the results of four different estimations, each of which is liable to experimental error, whereas in the chloride methods there is only one perfectly straightforward determination. The values for the total exchangeable bases in the soils examined were found to vary over the range 2.50 to 14.28 m.e. per 100 g. soil, with a variance of up to ± 0.2sm.e. per 100 g., corresponding to a percentage error of up to ± 4.7%. These figures are based on the analysis of 12 separate leachings of each soil with normal ammonium acetate solution of pH 7.00. This rather wide variance can be attributed to the fact that the exchangeable bases in some soils are more easily replaceable than in other soils. It is regretted that the shortage of time and the non-availability of a complete range of samples of all typical South African soils has prevented the attainment of an original objective, namely, a statistical evaluation of the base exchange figures for all South African soil types. It would also have been of great interest to have been able to establish exactly the composition of the double salt of calcium and magnesium, whose existence has been postulated to explain the effect of the Ca/Mg ratio on the results yielded by the first chloride method. Summary, p. 67-68.

The colloidal fraction is the vital part of a soil. These extremely minute particles determine the nature of the soil and are mainly responsible for its many and varied functions. The most important of these functions is perhaps the ability of the colloids to adsorb and exchange cations, the elements so essential to all organisms as building materials. When pure water is passed through a non-saline. soil, the leachate will contain very few dissolved cations. If, on the other hand, an electrolyte such as a weak solution of sodiun chloride, is passed through the same soil, the leachate will contain considerable quantities of calcium, magnesium and potassiun chlorides as well as much of the original sodium chloride. The number of equivalents of the cations collected will be approximately the same as the number of equivalents of sodium ions added. Sodium ions have displaced some of the calcian, magnesium and potassium ions from the soil. This phenomenon is known as cation exchange. Intro., p. 1.