Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 4 of 4
Full-Text Articles in Physical Sciences and Mathematics
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 …
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 …