Iron precipitate accumulations associated with waterways in drained coastal acid sulfate landscapes of eastern Australia

Iron precipitate accumulations from surface environments surrounding waterways (such as the side of drains and soil surface horizons) in acid sulfate soil landscapes were analysed for their mineralogy, micromorphology and chemical properties. Schwertmannite (Fe8(OH)5.5(SO4)1.25) was the dominant mineral in these accumulations. Goethite (α-FeOOH) was the other iron precipitate mineral identified in these accumulations and the data indicate that this iron mineral was formed from schwertmannite, often as pseudomorphs after schwertmannite. The schwertmannite in these accumulations had similar morphology and chemical properties to schwertmannite reported for environments affected by acid mine drainage. The activity of Fe3+ in the drainage waters in these landscapes appears to be controlled by schwertmannite during both low flow (dry season) and flood conditions. Iron precipitate accumulations contained appreciable amounts of stored acidity (i.e. titratable actual acidity of between 164 and 443 mol (H+) t–1, and 1900 to 2580 mol (H+) t–1 of schwertmannite upon complete conversion to goethite) that tends to buffer these waters to very acidic conditions (i.e. pHs ~3.0–3.5). The relationship between water quality (i.e. pH and sulfate concentration) and type of iron precipitate mineral formed should enable the mineralogy of the iron precipitates in these surface environments to be used to help identify the degree of severity of degradation in these acid sulfate soil landscapes and to monitor the effectiveness of remediation programmes.

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Oxidation rate of pyrite in acid sulfate soils: in situ measurements and modelling

Soil Research ◽

10.1071/sr03091 ◽

2004 ◽

Vol 42 (6) ◽

pp. 499 ◽

Cited By ~ 13

Author(s):

F. J. Cook ◽

S. K. Dobos ◽

G. D. Carlin ◽

G. E. Millar

Keyword(s):

Oxidation Rate ◽

Volume Ratio ◽

Soil Surface ◽

Biological Processes ◽

Acid Sulfate Soils ◽

Acid Sulfate ◽

The Difference ◽

Actual Acidity ◽

Sulfate Soils

The generation of acidity from oxidation of pyrite in acid sulfate soils requires the transport of oxygen into the soil profile. The sink for this oxygen will not only be the chemical reaction with pyrite but the biological processes associated with both microbial and plant respiration. The biological sinks in burning the oxygen (O2) will release CO2. The respiratory quotient which is the molar volume ratio of O2 : CO2 varies between 1.3 and 0.7 depending on the source of the organic matter being oxidised, but is generally 1.0. The oxidation of pyrite by oxygen will, by comparison with the biological processes, produce minor amounts of CO2 (if any) by reaction with intrinsic carbonate minerals. Gas samplers were installed into the soil at various depths and samples collected from these at approximately fortnightly intervals. The samples were analysed by gas chromatography and the CO2 and O2 profiles obtained. The flux of these gases was calculated and the difference between these attributed to the oxidation of pyrite. The flux difference varied over the period of sampling and on average gave an in situ oxidation rate of 11.5 tonnes H2SO4/ha.year. This is considerably more that the rate of export of acidity from this site and would explain the considerable actual acidity storage in these soils. A model is developed for steady state transport of oxygen into soils with an exponentially decreasing biological sink with depth and an exponentially increasing chemical (pyrite) sink with depth. The model is developed in non-dimensional variables, which allows the relative strengths and rates of increase or decrease in sink terms to be explored. This model does not explicitly treat the flow of oxygen in macropores. Other models that do explicitly calculate macropore flow are compared and found to give similar results. These results suggest that the use of biological or other sinks near the soil surface could be a useful method for reducing the oxidation rate of pyrite in acid sulfate soils.

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

Soil Research ◽

10.1071/sr03110 ◽

2004 ◽

Vol 42 (6) ◽

pp. 509 ◽

Cited By ~ 16

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.

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Changes of soils properties in the process of spontaneous afforestation of arable land in the territory of the Upper Dnister Beskid (Ukrainian Carpathians)

Visnyk of the Lviv University. Series Geography ◽

10.30970/vgg.2017.51.8904 ◽

2017 ◽

pp. 382-389

Author(s):

Iryna Shpakivska ◽

Ivanna Storozhuk

Keyword(s):

Organic Matter ◽

Chemical Elements ◽

Arable Land ◽

Chemical Properties ◽

Physical And Chemical Properties ◽

Closed Forest ◽

Actual Acidity ◽

Physical And Chemical ◽

And Chemical Properties ◽

Hydrolytic Acidity

The peculiarities soil transformation of stages of the spontaneous afforestation in the Upper Dnister Beskid region were evaluated. The afforestation ecosystems represented series of restoration succession of forest ecosystems: arable land → ruderal stage → grassland stage → shrub stage → closed forest. The changes of the basic physical and chemical properties of the brown soils of the Upper Dniester Beskid of different stages of the afforestation within the transect of v. Gvozdenec and v. Topilnytca (Starosambirsky district of the Lviv region) were investigated. It was established that the process of spontaneous afforestation of arable land on the territory of the Upper Dniester Beskid causes an increase in actual, potential and hydrolytic acidity in the direction from the arable land to the closed forest, as well as an increase in the amount of organic matter in the forest soils compared with the arable land. Want of agricultural cultivation of the territory and the process of spontaneous afforestation an increase in the content of organic acids and salts, in particular carbon (H2CO3), in the upper horizons of the soil, which leads to changes in the actual acidity in the soil profi le. In the direction from the arable land to the closed forest there are increases in the actual acidity. Spontaneous afforestation, especially due to coniferous trees, causes a change in the amount of hydrogen and aluminum in the soil solution. The upper humus horizons had higher hydrolytic acidity than humus transitions horizons, which is related plants fall on the soil surface and the redistribution of chemical elements in the soil profile. In post-arable soils, the amount of organic carbon increases due to want of organic fertilization with the economic part of the crops and its annual input from plant fallout. It was established that the arable plots content of organic matter is 2,97–3,32 % in forest areas – 4,02–4,30 %. Key words: brown soils, physical and chemical properties, afforestation, Upper Dnister Beskid.

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Factors contributing to the acid sulfate soil scalding process in the coastal floodplains of New South Wales, Australia

Soil Research ◽

10.1071/sr03076 ◽

2004 ◽

Vol 42 (6) ◽

pp. 587 ◽

Cited By ~ 11

Author(s):

Mark A. Rosicky ◽

Leigh A. Sullivan ◽

Peter G. Slavich ◽

Mike Hughes

Keyword(s):

New South ◽

New South Wales ◽

Pyrite Oxidation ◽

Soil Surface ◽

Soil Parameters ◽

Soil Core ◽

Acid Sulfate Soil ◽

Vegetative Cover ◽

Acid Sulfate ◽

South Wales

Acid sulfate soil (ASS) scalds are persistently bare areas of land, occurring in the coastal backswamps of New South Wales (NSW), Australia. This study aims to understand why particular areas become ASS scalds, while adjacent areas remain vegetated. Some important soil parameters are compared and field observations are summarised. Soil core sampling in both ASS-scalded land and surrounding areas of permanently vegetated paddocks has demonstrated similar pyrite concentrations and depth occurrence, soil salinity, and soil acidity (pH). As conditions are similar beneath both vegetated and non-vegetated land, there must be some additional factors influencing which areas become denuded. Several disparate (usually human-induced) events were found to cause initial loss of vegetative cover. Once the soil is bare, surface evaporation causes toxic solutes to build up quickly at the soil surface and ASS scalding is perpetuated. Some of the intervening events include fire, flood, flood-scouring, deliberate topsoil removal, surface pyrite oxidation, saltwater inundation of freshwater paddocks, saltwater exclusion from saltmarsh or mangroves, changes to the vegetation regimes, excessive vehicular traffic, and over-grazing. Backswamp management needs to ensure that land underlain by shallow pyritic layers (or with soil-water that is enriched with the toxic by-products of pyrite oxidation) is not laid bare by accident or design. Similar soil chemical conditions underlying both ASS scalds and the surrounding permanently vegetated paddocks suggest that much larger areas are potentially at risk of ASS scalding.

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Impact of sodium adsorption ratio of irrigation water on the structural form of two Vertosols used for cotton production

Soil Research ◽

10.1071/sr11083 ◽

2011 ◽

Vol 49 (6) ◽

pp. 481 ◽

Cited By ~ 5

Author(s):

S. D. Speirs ◽

S. R. Cattle ◽

G. J. Melville

Keyword(s):

Water Quality ◽

Irrigation Water ◽

Chemical Properties ◽

Exchange Capacity ◽

Structural Form ◽

Cotton Production ◽

Eastern Australia ◽

The Difference ◽

Chemical Attributes ◽

And Chemical Properties

In recent years, the production of cotton in Australia has been limited by the availability of irrigation water. To overcome this problem, poorer quality (Na+-rich) irrigation sources have been used in some situations, despite the effects elevated levels of Na+ may have on soil physical and chemical properties. This paper reports on changes in the surface-connected structural form attributes of two Vertosols from eastern Australia (one Red Vertosol, one Black Vertosol) after treatment with a range of different water-quality solutions. Intact soil columns from each of the Vertosols were irrigated through six wet–dry cycles using one of six treatment solutions with varying Na+ concentrations. Replicate columns for each treatment of each soil were analysed post-irrigation for selected chemical attributes. A second set of replicate columns was impregnated with a fluorescent resin post-irrigation, horizontally sectioned, and photographed under ultraviolet light. Image analysis was carried out on the section photographs to yield quantitative estimates of porosity (P), surface area (Sv), solid and pore star lengths (ls* and lp*), and solid and pore genus (gs and gp). Generally, the soil treated with the low-Na+ solution had the most desirable structural form attributes (larger P, Sv, and gp and smaller ls* and gs), while the soil treated with the high-Na+ solution had the least desirable structural attributes. The structural attributes and chemical properties of the Red Vertosol changed more markedly with water quality than did those of the Black Vertosol. The difference in response to water quality between these two soils is presumed to be related to the clay mineral suites and the exchange capacity of these soils; the Black Vertosol contains appreciably more smectite and has a much larger effective cation exchange capacity than the Red Vertosol.

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Spatial distribution and management of total actual acidity in an acid sulfate soil environment, McLeods Creek, northeastern NSW, Australia

CATENA ◽

10.1016/s0341-8162(02)00069-3 ◽

2003 ◽

Vol 51 (1) ◽

pp. 61-79 ◽

Cited By ~ 24

Author(s):

J Smith ◽

P van Oploo ◽

H Marston ◽

M.D Melville ◽

B.C.T Macdonald

Keyword(s):

Spatial Distribution ◽

Soil Environment ◽

Acid Sulfate Soil ◽

Acid Sulfate ◽

Actual Acidity

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Soil chemistry and acidification risk of acid sulfate soils on a temperate estuarine floodplain in southern Australia

Soil Research ◽

10.1071/sr15174 ◽

2016 ◽

Vol 54 (7) ◽

pp. 787 ◽

Cited By ~ 1

Author(s):

C. C. Yau ◽

V. N. L. Wong ◽

D. M. Kennedy

Keyword(s):

Soil Chemistry ◽

Acid Sulfate Soils ◽

Shell Material ◽

Acid Sulfate ◽

Estuarine Processes ◽

Acid Neutralising Capacity ◽

Eastern Australia ◽

Actual Acidity ◽

Sulfate Soils ◽

Soil And Water

The distribution and geochemical characterisation of coastal acid sulfate soils (CASS) in Victoria in southern Australia is relatively poorly understood. This study investigated and characterised CASS and sulfidic material at four sites (wetland (WE), swamp scrub (SS), woodland (WO) and coastal tussock saltmarsh (CTS)) on the estuarine floodplain of the Anglesea River in southern Australia. Shell material and seawater buffered acidity generated and provided acid-neutralising capacity (up to 10.65% CaCO3-equivalent) at the sites located on the lower estuarine floodplain (WO and CTS). The SS site, located on the upper estuarine floodplain, can potentially acidify soil and water due to high positive net acidity (>200molH+t–1) and a limited acid-neutralising capacity. High titratable actual acidity in the SS and WO profiles (>270molH+t–1) were the result of high organic matter in peat-like layers that can potentially contribute organic acids in addition to acidity formed from oxidation of sulfidic sediments. The results of the present study suggest that the environments and chemistry of acid sulfate soils in southern Australia are distinct from those located in eastern Australia; this may be related to differences in estuarine processes that affect formation of acid sulfate soils, as well as the geomorphology and geology of the catchment.

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Upland active acid sulfate soils from construction of new Stafford County, Virginia, USA, Airport

Soil Research ◽

10.1071/sr03085 ◽

2004 ◽

Vol 42 (6) ◽

pp. 527 ◽

Cited By ~ 15

Author(s):

D. S. Fanning ◽

Cary Coppock ◽

Z. W. Orndorff ◽

W. L. Daniels ◽

M. C. Rabenhorst

Keyword(s):

Land Surface ◽

Soil Surface ◽

Great Difficulty ◽

Acid Sulfate Soils ◽

Acid Sulfate Soil ◽

Acid Sulfate ◽

Salt Minerals ◽

Land Surfaces ◽

Sulfate Soils ◽

Steep Slopes

This paper reports on a situation where severe active acid sulfate soils were brought into existence by the construction of a new (opened in 2002) airport in Stafford County, VA, approximately 60 km south-west of Washington, DC. About 290 ha of new land surface was brought into existence that consisted of both scalped land surfaces on steep slopes, and spoil (fill), some of which was graded to provide level land surfaces for paved runways. Over 150 ha of ultra acidic (pH <3.5 at soil surface) post-construction acid sulfate soils remained barren for over 2 years before the acid sulfate soil situation was properly recognised. Construction took place in an originally dissected landscape with about 30 m of local relief. The construction was designed to balance the cut and fill areas so that soil materials would not need to be taken from the area or brought to it from other locations. This resulted in some deep cuts (scalped surfaces) in the higher parts of the landscapes, which retained slopes of about 25%. Great difficulty was encountered in establishing vegetation on these surfaces. The exposed sulfidic materials were dense, commonly on steep slopes, and developed low pHs, some <pH 2, after exposure. After a dry period in the autumn of 2001, sulfuric horizons crusted over with bitter hydrated sulfate salt minerals had formed in the surface of sulfidic materials originally exposed in 1999. By X-ray diffraction, halotrychite, Fe2+Al2(SO4)4.22H2O, was identified as a main white salt mineral and copiapite group minerals, e.g. Al2/3Fe3+4(SO4)6(OH)2.20H2O for aluminocopiapite, were identified as a yellow salt minerals. Information about, and photographs of, the site, soils, and drainage waters are presented, including examples of deleterious environmental impacts. Intensive reclamation/revegetation measures were initiated in 2002. These involved the application of high rates of lime stabilised biosolids (sewage sludge) incorporated to a depth of about 0.15 m to neutralise acidity and add organic matter and nutrients to the soils. These measures permitted the establishment of acid- and salt-tolerant grasses on the acid sulfate soils and caused dramatic increases in pH and drops in Fe and Al levels in stream waters leaving the site. However, they also caused initial large increases in ammonia/ammonium-N in the waters and subsequent increases in NO3-N in the waters. Experience with this and other similar sites demonstrates the need for engineers involved with earth-moving construction activities to be educated in the principles of acid sulfate soils so that the number of such disturbances that result in the creation of active acid sulfate soils can be lessened or, preferably, eliminated. Plans for recognition and reclamation of acid sulfate soil situations should be built into the construction plans and designs when it is necessary to disturb sulfidic materials.

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Soils of the Poplar Box (Eucalyptus populnea) communities of Eastern Australia.

The Rangeland Journal ◽

10.1071/rj9800017 ◽

1980 ◽

Vol 2 (1) ◽

pp. 17 ◽

Cited By ~ 7

Author(s):

AA Webb ◽

PJ Walker ◽

RH Gunn ◽

AT Mortlock

Keyword(s):

Soil Type ◽

New South ◽

Chemical Properties ◽

Soil Types ◽

Physical And Chemical Properties ◽

South Wales ◽

Eastern Australia ◽

Physical And Chemical ◽

Eucalyptus Populnea ◽

And Chemical Properties

Information on the soils of recognized poplar box (Eucalyptus populnea) communities has been collated from published and unpublished reports. Major soils have been described briefly in terms of morphology and some physical and chemical properties. Site data from a number of previous surveys was used in an attempt to identify soil type/vegeration relationships. Poplar box occurs on a very \\'ide range of soil types. Approximately half of the 1500 sites described in Queensland and New South Wales were on duple\ soils. The data indicate that poplar box prefers lighter textured soils such as uniform sands and massive earths in the western areas of its distribution but in the eastern, more mesic areas il occurs mainly on duplex clay soits.

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Ultra-fine grinding is not essential for acid sulfate soil tests

Soil Research ◽

10.1071/sr10196 ◽

2011 ◽

Vol 49 (5) ◽

pp. 439

Author(s):

David J. Lyons ◽

Angus E. McElnea ◽

Niki P. Finch ◽

Claire Tallis

Keyword(s):

Chemical Properties ◽

Test Results ◽

Acid Sulfate ◽

Fine Grinding ◽

Acid Neutralising Capacity ◽

Significant Difference ◽

Australian Standard ◽

Actual Acidity ◽

Ultra Fine Grinding ◽

Sulfate Soils

Australian Standard methods for acid sulfate soils (ASS) require the grinding of soil to <0.075 mm. A ring-mill or similar grinding apparatus is therefore needed. We investigated whether ring-mill grinding is required for accurate and reproducible test results and associated calculations (such as acid–base accounting), or if more conventional fine-grinding (i.e. <0.5 mm) is sufficient to obtain acceptable results. An initial experiment (unreplicated) was conducted on 52 soils comparing ring-mill and fine-grinding treatments, and this information was used to formulate final, more detailed experimental work on five soils from the same dataset. Soils from an ASS survey in coastal central Queensland were chosen to reflect the range of chemical properties found in ASS. Soils were analysed by the Chromium and SPOCAS suite of tests for the two grinding treatments. For those tests that follow a relatively vigorous extraction carried out with heating [such as chromium-reducible S, peroxide-oxidisable S and acid-neutralising capacity by back titration (ANCBT)], results were similar for the two grinding treatments. However, for those tests that follow a relatively mild extraction without heating (such as KCl-extractable S, HCl-extractable S and titratable actual acidity), significantly higher values (P < 0.05) were obtained for ring-mill ground soil. There was no significant difference in calculated net acidity between ring-mill grinding and fine-grinding for soils without excess ANC. For self-neutralising soils, fine-grinding gave significantly lower values of ANC than ring-mill grinding. It is uncertain whether ring-mill grinding gives a true reflection of the ANC available in the natural environment.

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