The response of partially oxidised acid sulfate soil materials to anoxia

Soil Research ◽  
2004 ◽  
Vol 42 (6) ◽  
pp. 515 ◽  
Author(s):  
Nicholas J. Ward ◽  
Leigh A. Sullivan ◽  
Richard T. Bush
Keyword(s):  
Organic Matter ◽  
Sulfide Oxidation ◽  
Management Strategies ◽  
Oxidation Products ◽  
Acid Sulfate Soil ◽  
Acid Sulfate ◽  
Anoxic Conditions ◽  
Inorganic Sulfur

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 <3.5), sulfide oxidation and acidification generally continued (albeit at much slower rates), most probably due to oxidation by Fe3+. Rapid sulfide re-formation occurred in the peat ASS material that had been oxidised for 63 days, with 0.47% reduced inorganic sulfur (SCR) formed over 60 days of anoxia. This substantial sulfide re-formation was accompanied by only a slight increase in pH. Minimal sulfide re-formation occurred in 2 of the ASS materials when placed in anoxic conditions, most likely due to a lack of readily available organic matter in these materials. The results show that the imposition of anoxic conditions on partially oxidised ASS materials is generally effective in decreasing the rates of further sulfide oxidation, acidification, and the production of soluble sulfide oxidation products. Biogeochemical sulfide formation consumes acidity; however, sulfide re-formation was ineffective in reversing acidification under the conditions of this experiment. The results indicate that the treatment of sites containing actual ASS materials by management strategies relying on oxygen exclusion need to be accompanied by other strategies that include acidty neutralisation or containment.

The acid flux dynamics of two artificial drains in acid sulfate soil backswamps on the Clarence River floodplain, Australia

Soil Research ◽  
2004 ◽  
Vol 42 (6) ◽  
pp. 623 ◽  
Author(s):  
S. G. Johnston ◽  
P. Slavich ◽  
P. Hirst
Keyword(s):  
Temporal Dynamics ◽  
Sulfide Oxidation ◽  
Soil Surface ◽  
Drainage Density ◽  
Oxidation Products ◽  
Acid Sulfate Soil ◽  
Flux Dynamics ◽  
Acid Sulfate ◽  
High K ◽  
Very High

The export of acidity, iron, aluminium, and sulfate to an estuary from 2 drains in acid sulfate soil backswamps was monitored over 18 months. The backswamps had similar geomorphology, stratigraphy, and drainage density, and comparable soil and groundwater acidity. However, the flux rates, temporal dynamics, and export pathways of acid and other sulfide oxidation products varied greatly and were controlled to first order by (i) the saturated hydraulic conductivity (K) of sulfuric horizons and (ii) the tidally influenced groundwater gradients. The site with very high K and large tidally influenced groundwater gradients had high acid flux rates (5300 mol H+/ha.year), chronic acid discharge, high drain water acid and metal concentrations, and the primary flux pathway was direct groundwater seepage (interflow/bypass flow) to the drain. The site with lower K and smaller groundwater gradients displayed low acid flux rates (50 mol H+/ha.year), infrequent, highly episodic discharge, and the primary flux pathway was dilute surface runoff following dissolution of sulfide oxidation products accumulated on the soil surface. Importantly, the majority of acid export at both sites occurred while the backswamp groundwater level was within a very narrow elevation range.

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.

Soil pH, oxygen availability, and the rate of sulfide oxidation in acid sulfate soil materials: implications for environmental hazard assessment

Soil Research ◽  
2004 ◽  
Vol 42 (6) ◽  
pp. 509 ◽  
Author(s):  
Nicholas J. Ward ◽  
Leigh A. Sullivan ◽  
Richard T. Bush
Keyword(s):  
Hazard Assessment ◽  
Oxygen Diffusion ◽  
Sulfide Oxidation ◽  
Oxygen Availability ◽  
Environmental Hazard ◽  
Acid Sulfate Soil ◽  
Acid Sulfate ◽  
Plastic Bags ◽  
Actual Acidity ◽  
Environmental Hazard Assessment

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 rate of sulfide oxidation was assessed. The ASS materials were incubated in: (i) gauze where oxygen diffusion was not restricted, and (ii) sealed 100-µm-thick plastic bags which greatly limited oxygen diffusion. When oxygen diffusion was not restricted, an accelerated oxidation of sulfide occurred when the pH decreased below pH 4.0. The accelerated rate of sulfide oxidation at such low pH did not occur when oxygen diffusion was limited. This study indicates that the initial pH of an ASS material is a useful additional indicator of the potential environmental hazard of an ASS material when oxygen is expected to be non-limiting, such as when ASS materials are excavated and stockpiled. The recommended action criteria need to be reassessed, as the data indicate that the current criteria are conservative for alkaline and neutral ASS materials, but should be lowered for all acidic ASS materials (i.e. pH <5.5) to 0.03% sulfide regardless of texture.

Reduced Inorganic Sulfur Speciation in Drain Sediments from Acid Sulfate Soil Landscapes

2006 ◽  
Vol 40 (3) ◽  
pp. 888-893 ◽  
Author(s):  
Edward D. Burton ◽  
Richard T. Bush ◽  
Leigh A. Sullivan
Keyword(s):  
Acid Sulfate Soil ◽  
Acid Sulfate ◽  
Inorganic Sulfur ◽  
Sulfur Speciation

Sulfide oxidation and acidification of acid sulfate soil materials treated with CaCO3 and seawater-neutralised bauxite refinery residue

Soil Research ◽  
2002 ◽  
Vol 40 (6) ◽  
pp. 1057 ◽  
Author(s):  
Nicholas J. Ward ◽  
Leigh A. Sullivan ◽  
Richard T. Bush
Keyword(s):  
Sulfide Oxidation ◽  
Pyrite Oxidation ◽  
Application Rate ◽  
The Other ◽  
Optimal Rate ◽  
Initial Increase ◽  
Acid Sulfate Soil ◽  
Acid Sulfate ◽  
Application Rates ◽  
Incubation Experiments

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 an excessive application rate (&gt;250% of the NR). There was minimal sulfide oxidation and no acidification after the addition of excess CaCO3 over the 180 days of incubation. The addition of excess SNBRR prevented acidification, but substantial sulfide oxidation still occurred. Following a brief initial increase in pH when sub-optimal rates of CaCO3 and SNBRR were applied, the treated ASS materials rapidly acidified. For three of the ASS materials the addition of sub-optimal amounts of CaCO3 had little impact on the rate of sulfide oxidation. However, for the other ASS material (a peat) both the rates of sulfide oxidation and acidification were accelerated by the addition of sub-optimal rates of CaCO3, resulting in higher soluble Fe and Al concentrations than in the untreated ASS materials. For some of the ASS materials, sub-optimal applications of SNBRR resulted in elevated soluble Al.

A modified chromium-reducible sulfur method for reduced inorganic sulfur: optimum reaction time for acid sulfate soil

Soil Research ◽  
2000 ◽  
Vol 38 (3) ◽  
pp. 729 ◽  
Author(s):  
L. A. Sullivan ◽  
R. T. Bush ◽  
D. M. McConchie
Keyword(s):  
Reaction Time ◽  
Rock Sample ◽  
Reaction Times ◽  
Acid Sulfate Soil ◽  
Acid Sulfate ◽  
Inorganic Sulfur ◽  
Modified Method ◽  
Optimum Reaction

Reaction times for 16 acid sulfate soil materials analysed using a modified chromium-reducible sulfur method varied between 10 and 15 min, regardless of whether the samples had been dried and ground prior to analysis or were analysed without pretreatment. The reaction time for a ground (<63 mm) pyritic rock sample was 20 min. An optimum reaction time of 20 min is recommended for analysing acid sulfate soil using the modified method; this reaction time is much less than the 1 h reaction time used in previous methods.

scholarly journals Mediterranean Coastal Lagoons: The Importance of Monitoring in Sediments the Biochemical Composition of Organic Matter

2019 ◽  
Vol 16 (18) ◽  
pp. 3466
Author(s):  
Monia Renzi ◽  
Francesca Provenza ◽  
Sara Pignattelli ◽  
Lucrezia Cilenti ◽  
Antonietta Specchiulli ◽  
...  
Keyword(s):  
Organic Matter ◽  
Biochemical Composition ◽  
Coastal Lagoons ◽  
Sediment Cores ◽  
Management Strategies ◽  
Sediment Layer ◽  
The European Union ◽  
Coastal Zones ◽  
Anoxic Conditions ◽  
Chl A

Transitional water ecosystems are targeted by the European Union (EU) Water Framework Directive (WFD, CE 2000/60) monitoring programs in coastal zones. Concerning sediments, activities performed for the WFD focus on a few variables concerning the biochemical composition of organic matter. Our research reports the effects of oxygen availability on the biochemical composition of organic matter in sediments to highlight levels of targeted variables in time and, according to the depth of sediment layer, both under oxygenated and anoxic conditions in a mesocosm study on sediment cores. Results provide evidence that tested factors of interest (i.e., disturbance type, oxygenic versus anoxic conditions; persistence time of disturbance, 0–14 days; penetration through sedimentary layers, 0–10 cm depth) are able to significantly affect the biochemical composition of organic matter in sediments. Large part of the variables considered in this study (total organic carbon (TOC), total phosphorous (TP), total sulphur (TS), Fe, carbohydrates (CHO), total proteins (PRT), biopolymeric carbon (BPC), chlorophyll-a (Chl-a) are significantly affected and correlated to the oxygenation levels and could be good early indicators of important changes of environmental conditions. Monitoring activities performed under WFD guidelines and management strategies of Mediterranean coastal lagoon ecosystems shall include the biochemical composition of organic matter in sediment to provide an exhaustive picture of such dynamic ecosystems.

The process of sulfide oxidation in some acid sulfate soil materials

Soil Research ◽  
2004 ◽  
Vol 42 (4) ◽  
pp. 449 ◽  
Author(s):  
N. J. Ward ◽  
L. A. Sullivan ◽  
D. M. Fyfe ◽  
R.T. Bush ◽  
A. J. P. Ferguson
Keyword(s):  
Sulfide Oxidation ◽  
Water Soluble ◽  
Oxidation Products ◽  
Total Acid ◽  
Sulfur Species ◽  
Acid Sulfate ◽  
Incubation Experiments ◽  
O2 Concentration ◽  
Order Of Magnitude ◽  
Sulfate Soils

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 (SAV) fraction increased in concentration by an order of magnitude over the initial 8 days of incubation. Oxygen (O2) concentration profiles indicated the presence of anoxic conditions in the centre of the incubating materials even after 16 days of exposure to the atmosphere enabling SAV formation to occur. The oxidation of the SAV fraction did not result in substantial acidification. A large proportion of the water-soluble iron released by sulfide oxidation was precipitated as iron oxides and hydroxides. Sulfate (SO42–) was the dominant sulfur species produced from sulfide oxidation in both ASS materials, although water-soluble SO42– was a poor indicator of the extent of sulfide oxidation. The sulfoxyanion intermediates, thiosulfate (S2O32–) and tetrathionate (S4O62–), were detected only in the early stages of incubation, with minimal amounts being detected after the initial 4 days. The relative abundance of these 2 intermediate sulfur species appeared to be dependent on the soil pH, with S4O62– dominating S2O32– in the more acidic ASS material (i.e. pH <6) as has been observed in previous studies. The diminishing presence of sulfoxyanion intermediates as oxidation progressed was indicative that ferric ion (Fe3+) and bacterial catalysis were driving the oxidation processes. While these sulfoxyanion intermediates only constituted a small percentage of the reduced inorganic sulfur (RIS) fraction, they accounted for up to 9.3% of the total soluble sulfur fraction. Elemental sulfur (S0) was not an important sulfide oxidation product in the ASS materials examined in this study.

scholarly journals Micromorphological evidence for mineral weathering pathways in a coastal acid sulfate soil sequence with Mediterranean-type climate, South Australia

Soil Research ◽  
2009 ◽  
Vol 47 (4) ◽  
pp. 403 ◽  
Author(s):  
R. M. Poch ◽  
B P. Thomas ◽  
R. W. Fitzpatrick ◽  
R. H. Merry
Keyword(s):  
Organic Matter ◽  
Sulfide Oxidation ◽  
South Australia ◽  
Thermal Conditions ◽  
Mineral Weathering ◽  
Solution Chemistry ◽  
Local Source ◽  
Coastal Environments ◽  
Calcareous Sand ◽  
Acid Sulfate

Soil micromorphology, using light microscopy and scanning electron microscopy (SEM), was used to describe detailed soil morphological and compositional changes and determine mineral weathering pathways in acid sulfate soils (ASS) from the following 2 contrasting coastal environments in Barker Inlet, South Australia: (i) a tidal mangrove forest with sulfidic material at St Kilda, and (ii) a former supratidal samphire area at Gillman that was drained in 1954 causing sulfuric material to form from sulfidic material. Pyrite framboids and cubes were identified in sulfidic material from both sites and are associated with sapric and hemic materials. Gypsum crystals, interpreted as a product of sulfide oxidation, were observed to have formed in lenticular voids within organic matter in the tidal mangrove soils at St Kilda. Sulfide oxidation was extensive in the drained soil at Gillman, evidenced by the formation of iron oxyhydroxide pseudomorphs (goethite crystallites and framboids) after pyrite and jarosite, and of gypsum crystals. Gypsum crystals occur where a local source of calcium such as shells or calcareous sand is present. Sporadic oxidation episodes are indicated by the formation of iron oxide and jarosite coatings around coarse biogenic voids. These observations indicate that mineral transformation pathways are strongly influenced by soil physico-chemical characteristics (i.e. oxidation rate, Eh, pH, soil solution chemistry, mineralogy, and spatial distribution of sulfides). This information has been used to illustrate the interrelationships of pyrite, carbonate, gypsum, jarosite, and organic matter and help predict soil evolution under changing hydro-geochemical, redoximorphic, and thermal conditions in soils from coastal environments.

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