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- Chromium reducible sulfur (5)
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- Monosulfidic black ooze (1)
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- Pyrite re-formation (1)
- Reduced inorganic sulfur (1)
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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Sample Pre-Treatment And The Determination Of Some Chemical Properties Of Acid Sulfate Soil Materials, Crystal Maher, Leigh Sullivan, Nicholas Ward
Sample Pre-Treatment And The Determination Of Some Chemical Properties Of Acid Sulfate Soil Materials, Crystal Maher, Leigh Sullivan, Nicholas Ward
Dr Nicholas J Ward
This study provides a systematic analysis of the effect of common acid sulfate soil (ASS) sample pre-treatments (namely freezing, oven drying, and grinding) on chromium-reducible sulfur (SCR) and water-soluble sulfate determinations. The results show that oven drying and hand grinding of the samples prior to analysis resulted in a decrease in SCR (i.e. up to 20% compared to those of frozen samples). This lower SCR value was partly due to the oxidation of sulfides in the oven. For oven-dried ASS materials, more intensive grinding in a ring mill increased SCR values, most likely by abrading coatings from pyrite grains. For …
The Response Of Partially Oxidised Acid Sulfate Soil Materials To Anoxia, Nicholas Ward, Leigh Sullivan, Richard Bush
The Response Of Partially Oxidised Acid Sulfate Soil Materials To Anoxia, Nicholas Ward, Leigh Sullivan, Richard Bush
Dr Nicholas J Ward
Four acid sulfate soil (ASS) materials were subjected to anoxia after varying periods of oxidation to determine the geochemical response of these types of soils to flooding. The response of the partially oxidised ASS materials to the exclusion of oxygen was variable. The rate of sulfide oxidation, acidification, and the production of soluble oxidation products such as sulfate, iron, and aluminium generally decreased markedly when subjected to anoxia. However, especially in the highly acidic ASS materials (i.e. pH 3+. Rapid sulfide re-formation occurred in the peat ASS material that had been oxidised for 63 days, with 0.47% reduced inorganic sulfur …
Sulfide Oxidation And Acidification Of Acid Sulfate Soil Materials Treated With Caco3 And Seawater-Neutralised Bauxite Refinery Residue, Nicholas Ward, Leigh Sullivan, Richard Bush
Sulfide Oxidation And Acidification Of Acid Sulfate Soil Materials Treated With Caco3 And Seawater-Neutralised Bauxite Refinery Residue, Nicholas Ward, Leigh Sullivan, Richard Bush
Dr Nicholas J Ward
Acid sulfate soil (ASS) materials that are subject to oxidation are often treated with neutralising agents to minimise the export of acidity that may result from pyrite oxidation. The effects of additions of both CaCO3 and seawater-neutralised bauxite refinery residue (SNBRR) on the oxidation of sulfides and acidification were assessed for 4 ASS materials using laboratory incubation experiments. As the application of sub-optimal rates of neutralising materials can occur for a variety of reasons, the effect of application rates were also examined. Two application rates were chosen; a sub-optimal rate [approximately 20% of the theoretical neutralising requirement (NR)] and …
Assessment Of Peroxide Oxidation For Acid Sulfate Soil Analysis. 2. Acidity Determination, Nicholas Ward, Leigh Sullivan, Richard Bush, Chuxia Lin
Assessment Of Peroxide Oxidation For Acid Sulfate Soil Analysis. 2. Acidity Determination, Nicholas Ward, Leigh Sullivan, Richard Bush, Chuxia Lin
Dr Nicholas J Ward
Total sulfidic acidity (TSA) and total potential acidity (TPA) are derived from peroxide oxidation of acid sulfate soil materials (ASS), and are measures of the sulfidic acidity and the net acidity (net acidity = sulfidic acidity + actual acidity – acid neutralising capacity), respectively. The TSA and TPA of 4 ASS materials were determined using a variety of peroxide oxidation procedures and compared with the sulfidic acidity and net acidity derived from the use of an acid–base accounting model. TSA and TPA values both varied greatly with each peroxide oxidation method used, and both measures were found to substantially underestimate …
Monosulfidic Black Ooze Accumulations In Sediments Of The Geographe Bay Area, Western Australia, Nicholas Ward, Richard Bush, Edward Burton, S Appleyard, S Wong, Leigh Sullivan, Paul Cheeseman
Monosulfidic Black Ooze Accumulations In Sediments Of The Geographe Bay Area, Western Australia, Nicholas Ward, Richard Bush, Edward Burton, S Appleyard, S Wong, Leigh Sullivan, Paul Cheeseman
Dr Nicholas J Ward
Mobilisation of sedimentary monosulfidic black ooze (MBO) may result in rapid deoxygenation and acidification of surface waters, and release of potentially toxic metals. This study examines the extent and nature of MBO accumulation in the Geographe Bay area, Western Australia. MBO accumulations were found to be widespread in benthic sediments of the Geographe Bay area with acid-volatile sulfide (AVS) contents as high as 320 μmol g−1. The MBO materials often had unusually high dissolved sulfide (S−II) concentrations in their pore-waters (up to 610 mg L−1) and elevated elemental sulfur (S0) contents (up to 51 μmol g−1). Dissolved S−II is able …
Improved Identification Of Sulfidic Soil Materials By A Modified Incubation Method, Leigh Sullivan, Nicholas Ward, Richard Bush, Edward Burton
Improved Identification Of Sulfidic Soil Materials By A Modified Incubation Method, Leigh Sullivan, Nicholas Ward, Richard Bush, Edward Burton
Dr Nicholas J Ward
This study examines the acidification behaviour and rate of sulfidic-sulfur oxidation in the incubation method that is currently used in soil taxonomies to identify sulfidic materials, for some clayey textured soil materials. ‘Sulfidic’ in these taxonomies identifies that a soil material is capable of becoming extremely acidic (i.e. pH < 4) as a result of oxidation of sulfide minerals contained in that soil material. As well as examining incubation slabs of acid sulfate soil materials with the standard 10 mm thickness, the utility of thinner (i.e. 2 mm thick) incubation slabs of these soil materials for identification of sulfidic soil materials …
Soil Ph, Oxygen Availability, And The Rate Of Sulfide Oxidation In Acid Sulfate Soil Materials: Implications For Environmental Hazard Assessment, Nicholas Ward, Leigh Sullivan, Richard Bush
Soil Ph, Oxygen Availability, And The Rate Of Sulfide Oxidation In Acid Sulfate Soil Materials: Implications For Environmental Hazard Assessment, Nicholas Ward, Leigh Sullivan, Richard Bush
Dr Nicholas J Ward
The potential environmental hazard of acid sulfate soil (ASS) materials is directly related to both the net acidity and the rate that actual acidity is released from these soil materials into the environment. While current environmental hazard assessment techniques for ASS materials are able to quantify the net acidity, they do not take account of differences in the rate of sulfide oxidation (the dominant source of actual acidity) and differences in the rate of acidification. In this study the rate of sulfide oxidation during incubation was examined for 4 ASS materials. The effect of pH and oxygen availability on the …
The Process Of Sulfide Oxidation In Some Acid Sulfate Soil Materials, Nicholas Ward, Leigh Sullivan, Diane Fyfe, Richard Bush, Angus Ferguson
The Process Of Sulfide Oxidation In Some Acid Sulfate Soil Materials, Nicholas Ward, Leigh Sullivan, Diane Fyfe, Richard Bush, Angus Ferguson
Dr Nicholas J Ward
The process of sulfide oxidation in acid sulfate soils (ASS) is complex, involving the formation of numerous oxidation products. In this study the sulfide oxidation process was examined in 2 ASS materials over a period of 36 days using laboratory incubation experiments. Both ASS materials experienced substantial sulfide oxidation and acidification during incubation. The oxidation of pyrite was the primary cause of acidification in these ASS materials. Although a decrease in magnetic susceptibility (χ) over the initial 4 days of incubation suggested the rapid oxidation of ferromagnetic iron monosulfide greigite (Fe3S4), the total acid volatile sulfur …
Assessment Of Peroxide Oxidation For Acid Sulfate Soil Analysis. 1. Reduced Inorganic Sulfur, Nicholas Ward, Leigh Sullivan, Richard Bush, Chuxia Lin
Assessment Of Peroxide Oxidation For Acid Sulfate Soil Analysis. 1. Reduced Inorganic Sulfur, Nicholas Ward, Leigh Sullivan, Richard Bush, Chuxia Lin
Dr Nicholas J Ward
The reduced inorganic sulfur fraction of 4 acid sulfate soil (ASS) materials was quantified using a variety of peroxide oxidation procedures. The temperature and duration of the peroxide oxidation were found to markedly affect the peroxide oxidisable sulfur determination. For 3 ASS materials with low total carbon content (i.e. <2.5% C), peroxide oxidisable sulfur underestimated the reduced inorganic sulfur fraction, with the peroxide oxidisable sulfur determinations being as low as 42% of those determined using chromium reducible sulfur technique. The precipitation of jarosite during peroxide oxidation was a major factor contributing to the underestimation of reduced inorganic sulfur in these materials. Apparent losses of sulfur of approximately 25% on average occurred during peroxide oxidation budget accounting; this also contributed towards the observed underestimation of reduced inorganic sulfur. It is most likely that these unaccounted losses are due to atmospheric losses of sulfur. In a peat ASS, one of the peroxide oxidation methods overestimated the reduced inorganic sulfur fraction and was attributed to the release of a large reserve of organic sulfur in this material by the peroxide. This study shows the peroxide oxidation methods examined here are subject to substantial interferences. Consequently these peroxide oxidation methods are unable to reliably provide accurate measurements of the reduced inorganic sulfur fraction in ASS materials