Assessment of peroxide oxidation for acid sulfate soil analysis. 2. Acidity determination

Soil Research ◽  
2002 ◽  
Vol 40 (3) ◽  
pp. 443 ◽  
Author(s):  
Nicholas J. Ward ◽  
Leigh A. Sullivan ◽  
Richard T. Bush ◽  
Chuxia Lin
Keyword(s):  
Soil Analysis ◽  
Mineral Dissolution ◽  
Peroxide Oxidation ◽  
Acid Sulfate Soil ◽  
Acid Base ◽  
Acid Sulfate ◽  
Acid Base Accounting ◽  
Total Potential ◽  
Acid Neutralising Capacity ◽  
Potential Acidity

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 (i.e. by 23–85%) both sulfidic acidity (as determined from the chromium reducible sulfur content) and net acidity (as determined by acid–base accounting). A major cause of this underestimation of acidity was the retention of acidity through the precipitation of jarosite during peroxide oxidation. Substantial clay mineral dissolution appears to have occurred during peroxide oxidation of the ASS materials, as indicated by increased soluble aluminium. Such dissolution may contribute to the underestimation of both sulfidic and net acidity for the ASS materials using peroxide oxidation methods. The loss of acidity to the atmosphere was identified as a possible additional interference. This study shows the peroxide oxidation methods examined here are subject to substantial interferences, which caused large underestimations of acidity, and consequently, are unable to reliably provide accurate measurements of sulfidic and net acidity in ASS materials. pyritic sulfur, total potential acidity, total sulfidic acidity, net acidity, jarosite, acid budget, acid neutralising capacity.

Assessment of peroxide oxidation for acid sulfate soil analysis. 1. Reduced inorganic sulfur

Soil Research ◽  
2002 ◽  
Vol 40 (3) ◽  
pp. 433 ◽  
Author(s):  
Nicholas J. Ward ◽  
Leigh A. Sullivan ◽  
Richard T. Bush ◽  
Chuxia Lin
Keyword(s):  
Soil Analysis ◽  
Total Carbon ◽  
Peroxide Oxidation ◽  
Acid Sulfate Soil ◽  
Acid Sulfate ◽  
Total Carbon Content ◽  
Inorganic Sulfur ◽  
Sulfur Determination ◽  
Pyritic Sulfur ◽  
Large Reserve

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. pyritic sulfur, peroxide oxidisable sulfur, chromium reducible sulfur, jarosite, sulfur budget.

Effects of Bauxsol™ on the immobilisation of soluble acid and environmentally significant metals in acid sulfate soils

Soil Research ◽  
2002 ◽  
Vol 40 (5) ◽  
pp. 805 ◽  
Author(s):  
Chuxia Lin ◽  
Malcolm W. Clark ◽  
David M. McConchie ◽  
Graham Lancaster ◽  
Nick Ward
Keyword(s):  
Heavy Metals ◽  
Simulation Experiment ◽  
Acid Sulfate Soils ◽  
Acid Sulfate Soil ◽  
Acid Sulfate ◽  
Metal Hydroxides ◽  
Acid Neutralising Capacity ◽  
Soluble Acid ◽  
Decreasing Ph ◽  
Sulfate Soils

The effects of Bauxsol, an abundant industrial by-product, on the immobilisation of soluble acid and a range of potentially environmentally toxic metals in artificial and natural acid sulfate soils were investigated. The acid neutralising capacity of Bauxsol increased with decreasing pH, which is probably provided not only by basic metal hydroxides, carbonates, and hydroxycarbonates but also by protonation of variably charged particles (e.g. gibbsite and hematite) present in Bauxsol. Simulation experiment results show that the removal of 9 tested environmentally significant heavy metals can be enhanced by addition of BauxsolTM; an exception was Co. The removal of the added soluble heavy metals by the BauxsolTM-soil mixtures shows a preferential order of Pb &gt; Fe &gt; Cr &gt; Cu &gt; Zn &gt; Ni &gt; Cd &gt; Co &gt; Mn. For the natural acid sulfate soil without added synthesised metal solution, the retention of the investigated environmentally significant metals is in the following decreasing order : Al &gt; Zn &gt; Fe &gt; Co &gt; Mn.

Acidity fractions in acid sulfate soils and sediments: contributions of schwertmannite and jarosite

Soil Research ◽  
2013 ◽  
Vol 51 (3) ◽  
pp. 203 ◽  
Author(s):  
Chamindra L. Vithana ◽  
Leigh A. Sullivan ◽  
Richard T. Bush ◽  
Edward D. Burton
Keyword(s):  
Correction Factor ◽  
Soil Samples ◽  
Acid Sulfate Soils ◽  
Peroxide Oxidation ◽  
Acid Base ◽  
Acid Sulfate ◽  
Soils And Sediments ◽  
Actual Acidity ◽  
Sulfate Soils

In Australia, the assessment of acidity hazard in acid sulfate soils requires the estimation of operationally defined acidity fractions such as actual acidity, potential sulfidic acidity, and retained acidity. Acid–base accounting approaches in Australia use these acidity fractions to estimate the net acidity of acid sulfate soils materials. Retained acidity is the acidity stored in the secondary Fe/Al hydroxy sulfate minerals, such as jarosite, natrojarosite, schwertmannite, and basaluminite. Retained acidity is usually measured as either net acid-soluble sulfur (SNAS) or residual acid soluble sulfur (SRAS). In the present study, contributions of schwertmannite and jarosite to the retained acidity, actual acidity, and potential sulfidic acidity fractions were systematically evaluated using SNAS and SRAS techniques. The data show that schwertmannite contributed considerably to the actual acidity fraction and that it does not contribute solely to the retained acidity fraction as has been previously conceptualised. As a consequence, SNAS values greatly underestimated the schwertmannite content. For soil samples in which jarosite is the only mineral present, a better estimate of the added jarosite content can be obtained by using a correction factor of 2 to SNAS values to account for the observed 50–60% recovery. Further work on a broader range of jarosite samples is needed to determine whether this correction factor has broad applicability. The SRAS was unable to reliably quantify either the schwertmannite or the jarosite content and, therefore, is not suitable for quantification of the retained acidity fraction. Potential sulfidic acidity in acid sulfate soils is conceptually derived from reduced inorganic sulfur minerals and has been estimated by the peroxide oxidation approach, which is used to derive the SRAS values. However, both schwertmannite and jarosite contributed to the peroxide-oxidisable sulfur fraction, implying a major potential interference by those two minerals to the determination of potential sulfidic acidity in acid sulfate soils through the peroxide oxidation approach.

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