scholarly journals Acid sulfate soils and acid drainage, Lower Shoalhaven floodplain, New South Wales

2010 ◽  
Vol 16 (2) ◽  
pp. 56 ◽  
Author(s):  
M I Pease ◽  
A G Nethery ◽  
A R. M Young
Keyword(s):  
New South ◽  
New South Wales ◽  
Acid Sulfate Soils ◽  
Acid Sulfate ◽  
Acid Drainage ◽  
South Wales ◽  
Sulfate Soils

Redistribution of monosulfidic black oozes by floodwaters in a coastal acid sulfate soil floodplain

Soil Research ◽  
2004 ◽  
Vol 42 (6) ◽  
pp. 603 ◽  
Author(s):  
Richard T. Bush ◽  
Leigh A. Sullivan ◽  
Diane Fyfe ◽  
Scott Johnston
Keyword(s):  
New South ◽  
Flood Mitigation ◽  
Acid Sulfate Soils ◽  
Fish Kill ◽  
Acid Sulfate ◽  
South Wales ◽  
North Eastern ◽  
Drainage Canals ◽  
Sulfate Soils ◽  
Thick Layers

The observations presented in this paper illustrate that significant amounts of monosulfidic black oozes (MBO) were eroded from flood mitigation drainage canals and redistributed across a coastal floodplain during a flood event associated with extreme deoxygenation and a massive fish kill. MBO are organic materials enriched in iron monosulfides and thick layers can accumulate in drains affected by acid sulfate soils. Laboratory studies have demonstrated that MBO can react rapidly when brought into suspension to completely consume dissolved oxygen. The abundance of MBO in flood mitigation drains and their extreme reactivity implicated MBO in the acute deoxygenation of the Richmond River, north-eastern New South Wales, Australia, following a major flood in February 2001. The field observations of MBO redistribution provide valuable evidence to help explain how these materials may interact and contribute to the deoxygenation of floodwaters.

Impact of soil consolidation and solution composition on the hydraulic properties of coastal acid sulfate soils

Soil Research ◽  
2008 ◽  
Vol 46 (2) ◽  
pp. 112 ◽  
Author(s):  
Thi Minh Hue Le ◽  
An Ninh Pham ◽  
Richard N. Collins ◽  
T. David Waite
Keyword(s):  
Hydraulic Conductivity ◽  
Field Measurements ◽  
Coastal Development ◽  
Soil Consolidation ◽  
Acid Sulfate Soils ◽  
Acid Sulfate ◽  
Soil Subsidence ◽  
South Wales ◽  
Consolidation Coefficient ◽  
Sulfate Soils

Acid sulfate soils (ASS) are distributed worldwide on coastal floodplains, presenting a great challenge to coastal development and urbanisation. Upon oxidation, these soils become stratified with visibly distinguishable soil strata that are progressively less oxidised with depth. In this study, the geotechnical properties, quantified by hydraulic conductivity and consolidation coefficient, of an ASS profile from the Tweed River floodplain, north-eastern New South Wales, Australia, were investigated at a laboratory scale and compared with results obtained from the field. Measurements were conducted with a Rowe cell (or hydraulic consolidometer) by controlled compressive and pore water pressures. The results indicated that hydraulic conductivity and consolidation coefficient values gradually decreased with increasing consolidation pressure or decreasing void ratio, but were significantly higher for the more oxidised ASS horizons. These results suggest that controlled soil consolidation along ASS drainage banks may prove to be effective at reducing acid discharge. Passing low pH (pH 3) or high cation concentration (50 mm CaCl2) solutions through intact consolidated potential ASS samples did not induce changes in the hydraulic conductivity or consolidation coefficient of this material indicating that ASS soil ripening involves more than acidification reactions, and the practice of flushing drains with high ionic strength estuarine tidal waters is unlikely to induce soil subsidence as a result of ASS structural change and clay flocculation.

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

Soil Research ◽  
2004 ◽  
Vol 42 (6) ◽  
pp. 587 ◽  
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.

Soil properties in and around acid sulfate soil scalds in the coastal floodplains of New South Wales, Australia

Soil Research ◽  
2004 ◽  
Vol 42 (6) ◽  
pp. 595 ◽  
Author(s):  
Mark A. Rosicky ◽  
Leigh A. Sullivan ◽  
Peter G. Slavich ◽  
Mike Hughes
Keyword(s):  
Sulfur Content ◽  
Surface Soil ◽  
New South ◽  
New South Wales ◽  
Low Ph ◽  
Acid Sulfate Soil ◽  
Acid Sulfate ◽  
Soil Layers ◽  
Ph Values ◽  
South Wales

Soil profiles in 10 persistently bare areas (i.e. scalds), mainly located in coastal backswamps of New South Wales, Australia, were examined for chromium-reducible sulfur content and selected chemical properties. At 5 of the sites, the adjacent paddocks with vegetation cover were also examined. All of the tested sites had been affected by the extensive drainage of the surrounding acid sulfate soil (ASS) landscapes and the consequent oxidation of pyrite. All sites had low pH values in the surface soil layers and these low pH values extended for up to 150 cm into the underlying unoxidised blue/grey pyritic estuarine gels. This can be attributed to the downward diffusion of acidity, either produced in the overlying oxidised zones of these soils or transported laterally across the landscape to these low-lying areas. Acidified unoxidised pyritic zones 120 cm thick can evidently form within several decades after drainage disturbance. At the scalded sites the depth from the soil surface to the main pyritic zone varied from the surface to >200 cm depth, indicating that this variable is not critical to ASS scald formation. For most of the sites examined, the chromium-reducible sulfur contents in the surface soil layers were appreciably higher than those in the immediately underlying soil layers. In most of the vegetated sites the chromium-reducible sulfur content in the surface layers was considerably higher than for the adjacent scalded site. The conditions necessary for pyrite formation (i.e. adequate supplies of organic matter, soluble iron, sulfate, and waterlogging) were found to exist at all sites, and the pyrite accumulations in these surface soil layers are considered to be neo-formed. The vegetated soil-profile pyrite and pH results were very similar to their scalded counterparts except that they had an extra 20–40 cm layer of vegetation and mulch that was missing from the scalded profiles. This indicates that there is considerable potential for more extensive scalding in these ASS areas.

Multi-stakeholder benchmarking: clarifying attitudes and behaviour from complexity and ambiguity

2000 ◽  
Vol 40 (4) ◽  
pp. 595 ◽  
Author(s):  
A. C. Woodhead ◽  
P. S. Cornish ◽  
P. G. Slavich
Keyword(s):  
State Government ◽  
Best Practice ◽  
Social Issues ◽  
Continuous Process ◽  
Acid Sulfate Soils ◽  
Acid Sulfate ◽  
South Wales ◽  
Open Questions ◽  
Multi Stakeholder ◽  
Sulfate Soils

Developing an understanding of a major environmental issue with multiple stakeholders is complex. Each stakeholder has a different perspective, level of knowledge and institutional focus. Acid sulfate soils on New South Wales coastal catchments are an emotive and polarising issue for the many stakeholders involved. Conflict over acid sulfate soils is therefore newsworthy, and the broader community is introduced to different stakeholders from these polarising viewpoints. Consequently, cane and cattle producers, who benefit from the draining of acid sulfate soils, are portrayed as perpetrators. Oyster farmers and fishers, who incur the cost of acidified water, are portrayed as victims, while local and state government agencies, who have responsibility for regulation, are variously portrayed as either heavy-handed bureaucrats or toothless tigers. Multi-stakeholder benchmarking has been developed to clarify complexity and ambiguities. By establishing indicators for documenting and understanding change in stakeholder attitude and behaviour it aims to decrease the divisiveness and degree of the polarised opinions. Benchmarking is a continuous process of measurement that identifies the best and compares against the best. Multi-stakeholder benchmarking uses multiple methods to establish quantitative data which, along with qualitative data are used to develop a deeper understanding of the complex social issues. It aims to empower individuals and groups while supporting extension and processes of change. First, information about social and economic issues is established by identifying and surveying stakeholders, using both quantitative ‘closed’ or explicit questions and qualitative ‘open’ questions for non-structured responses. Second, qualitative research, conducted in focus groups of subsampled survey respondents, validates and explores the survey results. During this stage, unique characteristics of the groups are defined, compared and best practices are identified. Results from these 2 stages are communicated back to the stakeholders, taking care to use non-judgemental language. Finally, best practice goals are defined, investigated and transferred within the same or other stakeholder groups. This paper proposes multi-stakeholder benchmarking as a new benchmarking process, and discusses the application of it to a complex environmental problem, acid sulfate soils. Multi-stakeholder benchmarking provides an important opportunity for stakeholders to voice their view on how environmental issues can be best managed and for determining which practices they wish to change. Further it provides information for education program development and evaluation, and facilitates the process of change. Acid sulfate soils stakeholders’ positive responses to non-judgemental information, that clarifies their position, and helps identify the way forward, suggest that multi-stakeholder benchmarking is applicable to other multi-stakeholder environmental problems.

Surface and sub-surface salinity in and around acid sulfate soil scalds in the coastal floodplains of New South Wales, Australia

Soil Research ◽  
2006 ◽  
Vol 44 (1) ◽  
pp. 17 ◽  
Author(s):  
Mark A. Rosicky ◽  
Peter Slavich ◽  
Leigh A. Sullivan ◽  
Mike Hughes
Keyword(s):  
New South ◽  
New South Wales ◽  
Pyrite Oxidation ◽  
Soil Surface ◽  
Acid Sulfate Soil ◽  
Surface Salinity ◽  
Deep Soil ◽  
Acid Sulfate ◽  
South Wales ◽  
Land Denudation

Two-metre-deep soil profiles at 10 acid sulfate soil (ASS) scalds along the coast of New South Wales (NSW), Australia, were examined for salinity indicators. At 5 of the sites, permanently vegetated areas adjacent to the ASS-scalded land were also tested. Throughout the profiles, most sites had high soluble chloride (Cl−) concentrations (≤17 mg/g soil) and high soluble sulfate (SO42−) concentrations (≤17 mg/g soil). Very low Cl− : SO42− ratios (≤3) indicated active pyrite oxidation. Soil salinity (measured as electrical conductivity, EC) was extremely high in the top 2 m of most of the ASS scalds when related to the growth requirements of the typical introduced pasture species that were planted in these areas following drainage. This allows salinity, in addition to the extremely low pH of the surface soils, to contribute to land denudation, which can instigate or perpetuate pyrite oxidation and ASS-related land scalding. Although the sites had shallow watertables and soil-moisture content was high, the surface soil (top 0.10 m) of the scalds had consistently higher soluble Cl− and SO42− concentrations and EC than adjacent vegetated areas. All coastal ASS areas investigated, typically freshwater backswamps used for cattle grazing, were underlain by estuarine-derived sediments containing saline ground water. The results demonstrate that revegetation of ASS scalds must include investigation and management of salinity, in addition to acidity, within the soil profile and at the soil surface.

Techniques for revegetation of acid sulfate soil scalds in the coastal floodplains of New South Wales, Australia: ridging, mulching and liming in the absence of stock grazing

2006 ◽  
Vol 46 (12) ◽  
pp. 1589 ◽  
Author(s):  
M. A. Rosicky ◽  
P. Slavich ◽  
L. A. Sullivan ◽  
M. Hughes
Keyword(s):  
Soil Moisture ◽  
Root Zone ◽  
New South ◽  
Combined Treatment ◽  
New South Wales ◽  
Soil Parameters ◽  
Acid Sulfate Soil ◽  
Acid Sulfate ◽  
South Wales ◽  
Vegetation Species

Two revegetation field trials were undertaken on chronically bare acid sulfate soil scalds on grazing properties in the Hawkesbury and Macleay catchments of New South Wales, Australia. The aim was to test the effectiveness of various low cost and readily accessible techniques to encourage revegetation (via existing seedbank or surrounding vegetation) of the scalded sites. The trial at the more efficiently drained Hawkesbury site used a combined treatment of ridging (R), mulching (M) and liming (L) (i.e. R–M–L) compared with a control, within a fenced area. At the more waterlogged Macleay site, various elements of the combined treatment (i.e. R, M, R–M, R–L, R–M–L) were compared with a control, within a fenced area. Vegetation occurrence, biomass and species were tested, along with pertinent soil parameters (pH, salinity, soil moisture, soluble metals). Soil testing was undertaken at 2 depth levels to represent the seed germination zone (0–1 cm), and the potential root zone (1–10 cm). At the Hawkesbury site, the combined treatment (R–M–L) caused significantly greater vegetation occurrence and biomass, lower salinity, higher pH and increased soil moisture. At the Macleay site, results were more variable, but similar to the Hawkesbury trial as the site dried out. Mulching was the single most important treatment. All mulched sites had significantly more vegetation than the control, reaching 100% coverage in the R–M–L plots. Stock exclusion alone produced minimal results. Ridging alone was counterproductive. Liming without mulching caused proliferation of an insubstantial and transient vegetation species (Isolepis inundata). Most interesting was the different vegetation species encouraged by the different mulch treatments: treatment M was dominated by the sedge, Eleocharis acuta; treatment R–M was an even mix of Eleocharis acuta and native water-tolerant grasses (Paspalum distichum and Pseudoraphis paradoxa); treatment R–M–L was dominated by the aforementioned native grasses. These grasses are highly favoured for both economic (highly palatable to stock) and environmental (thick mulch cover, self seeding) objectives. The results demonstrate that revegetation of acid sulfate soil scalds is possible, and different treatments can influence vegetation species composition.

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