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17. Nutritional traits of riverine eucalypts across lowland catchments in southeastern Australia

Author

Fernando, Denise R., primary, Dyer, Fiona, additional, Gehrig, Susan, additional, Capon, Sam, additional, Fernando, Anthony E., additional, George, Amy, additional, Campbell, Cherie, additional, Tschierschke, Alica, additional, Palmer, Gary, additional, Davies, Micah, additional, Kinsela, Andrew S., additional, Collins, Richard N., additional, Nolan, Martin, additional, and Doody, Tanya, additional

Published
2021
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22. Impact of soil consolidation and solution composition on the hydraulic properties of coastal acid sulfate soils

Author

Le, Thi Minh Hue, Pham, An Ninh, Collins, Richard N., and Waite, T. David

Subjects
Hydraulics -- Research, Soils -- Properties -- Composition -- Research, Soil chemistry -- Research, Sulfuric acid -- Properties -- Research, Agricultural industry, Earth sciences
Abstract

Acid sulfate soils (ASS) are distributed worldwide on coastal floodplains, presenting a great challenge to coastal development and urbanisation. Upon oxidation, these soils become stratified with visibly distinguishable soil strata that are progressively less oxidised with depth. In this study, the geotechnical properties, quantified by hydraulic conductivity and consolidation coefficient, of an ASS profile from the Tweed River floodplain, north-eastern New South Wales, Australia, were investigated at a laboratory scale and compared with results obtained from the field. Measurements were conducted with a Rowe cell (or hydraulic consolidometer) by controlled compressive and pore water pressures. The results indicated that hydraulic conductivity and consolidation coefficient values gradually decreased with increasing consolidation pressure or decreasing void ratio, but were significantly higher for the more oxidised ASS horizons. These results suggest that controlled soil consolidation along ASS drainage banks may prove to be effective at reducing acid discharge. Passing low pH (pH 3) or high cation concentration (50 mM Ca[Cl.sub.2]) solutions through intact consolidated potential ASS samples did not induce changes in the hydraulic conductivity or consolidation coefficient of this material indicating that ASS soil ripening involves more than acidification reactions, and the practice of flushing drains with high ionic strength estuarine tidal waters is unlikely to induce soil subsidence as a result of ASS structural change and clay flocculation. Additional keywords: Darcy's law, acid sulphate soils, void ratio, hydraulic conductivity, consolidation coefficient, Rowe cell., Introduction Coastal acid sulfate soils (ASS) in Australia, and worldwide, were generally deposited as unconsolidated sediments during the Holocene and contain (or contained) sulfidic minerals commonly in the form of [...]

Published
2008

24. Transformation and fixation of Zn in two polluted soils by changes of pH and organic ligands

Author

Collins, Richard N., Merrington, Graham, McLaughlin, Mike J., and Morel, Jean-Louis

Subjects
Soil pollution -- Research, Agricultural industry, Earth sciences
Abstract

Although the movement of Zn from the solid to the solution phase of soils is a significant process preceding plant uptake, the quantity of metal that can be solubilised through rhizosphere processes is also extremely important. Therefore, the consequences of plant-derived organic ligands and changes in pH on the isotopically exchangeable quantity of Zn (E value) were examined in a polluted acid and calcareous soil. Variations in pH were facilitated through the use of dilute NaOH or HN[O.sub.3] solutions. The organic ligands studied included 0.25-5 mM concentrations of sodium tartrate, the free acid and sodium salt of citrate, histidine, and deoxymugineic acid. As expected, the organic ligands and a reduction in pH increased the solution concentration of Zn in these soils. Furthermore, through the application of isotopic dilution techniques, it was determined that some of these organic ligands could significantly increase the quantity of isotopically exchangeable Zn. However, with the exception of the 5 mM sodium citrate treatment in the calcareous soil, pH was the overriding parameter that effected changes in the E value. Reducing the pH by approximately 2 units increased the E value by 39 and 80%, respectively, in the acid and calcareous soil. Conversely, evidence for Zn fixation (a decrease of the E value) was observed in the acid soil when pH was increased. The exudation of organic ligands and variations of pH induced by plants have the potential to significantly vary the quantity of phytoavailable Zn in these 2 polluted soils. Additional keywords: E value, isotopically exchangeable Zn, citrate, tartrate, histidine, deoxymugineic acid., Introduction The concentration of Zn in soil solution (the free cation and its complexes) is largely controlled by the equilibrium that it has with the quantity of metal associated with [...]

Published
2003

26. Determination of metal-EDTA complexes in soil solution and plant xylem by ion chromatography-electrospray mass spectrometry

Author

Collins, Richard N., Onisko, Bruce C., McLaughlin, Michael J., and Merrington, Graham

Subjects
Chemical industry -- Research, Instrument industry -- Research, Specialty chemicals industry -- Research, Environmental issues, Science and technology
Abstract

Ethylenediaminetetraacetic acid (EDTA) in plant xylem exudate and soil solution is measured using an ion chromatography-electrospray mass spectrometry (IC-MS) method. MS chromatogram results for the samples are graphed and the role of chelators is discussed in depth.

Published
2001

34. Effect of Shewanella oneidensison the Kinetics of Fe(II)-Catalyzed Transformation of Ferrihydrite to Crystalline Iron Oxides

Author

Xiao, Wei, Jones, Adele M., Li, Xiaomin, Collins, Richard N., and Waite, T. David

Abstract

Iron (oxyhydr)oxides are widespread in natural and engineered systems, potent adsorbents of contaminants and a source of energy for iron-reducing bacteria. Microbial reduction of iron (oxyhydr)oxides results in the formation of Fe(II) which can induce the transformation of these iron minerals, typically from less crystalline to more crystalline forms, affecting the biogeochemical cycling of iron and the behavior of any species adsorbed to the iron (oxyhydr)oxides. Factors influencing the transformation rate of the poorly crystalline iron (oxyhydr)oxide, ferrihydrite, to more crystalline forms in the presence of the iron reducing bacterium Shewanella oneidensisMR-1 are investigated under controlled laboratory conditions in this work. In particular, the amount of Fe(II) produced increased the transformation rate while increasing concentrations of the electron donor, lactate, decreased the rate. Using kinetic parameters determined from abiotic controls, the results of transformation experiments in the presence of Shewanella oneidensiswere modeled with this exercise revealing that less goethite and more lepidocrocite formed than expected. Conversely, studies using the Shewanellaexudate only, containing biogenic Fe(II), displayed rates of transformation that were satisfactorily modeled using these abiotic control kinetic parameters. This result suggests that the physical presence of the microbes is pivotal to the reduction in ferrihydrite transformation rate observed in the biotic experiments relative to the analogous abiotic controls.

Published
2024
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42. Influence of Dissolved Silicate on Rates of Fe(II) Oxidation

Author

Kinsela, Andrew S., primary, Jones, Adele M., additional, Bligh, Mark W., additional, Pham, An Ninh, additional, Collins, Richard N., additional, Harrison, Jennifer J., additional, Wilsher, Kerry L., additional, Payne, Timothy E., additional, and Waite, T. David, additional

Published
2016
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