Industry 

 

 

 

 

 

Issue # 60                    June 2012   

Happy 60th birthday, ASSAY ! 

Greetings and welcome to the 60th issue of ASSAY – the national acid sulfate soils newsletter. The first issue was published back in March 1993, making ASSAY the longest running Australian NRM newsletter. This edition continues the run of great stories from right around the country. 

Researchers have published the first documented occurrences of redspot disease identified in the Murray Darling Basin. Redspot was previously thought to be restricted to coastal drainage systems. 

At Herons Creek in NSW, road excavation works uncovered some noxious materials that made several workers on the site feel extremely nauseous. Initial reports were that ASS was implicated. 

In other news, new acid sulfate soil content has just recently been hosted on the Federal government’s DSEWPaC website and is now up and running. The weblink is available here. 

              Happy reading… Simon

Stories and places… 

Pg 2: WA ‐ Perth wetlands 

Pg 11: Maintaining a constructed wetland 

Pg 10: WA ‐ Review of ASS disposal  

Pg 6: New ASS concepts for classification 

Pg 3: Herons Creek & ASS 

Pg 4: QLD – mapping Pine Rivers 

Pg 19: International ASS Conference, Vaasa, Finland ‐ August 2012 

 

Coastal wetlands turn toxic 

Source: Michelle Wheeler, The West Australian ‐ 17 May 2012 

 

Toxic heavy metals and sulfuric acid have developed at Perth wetlands because of decades of drought, over‐extraction of groundwater and drainage for housing, according to a leading environmental scientist. 

Edith Cowan University ecology professor Pierre Horwitz, whose research group has held a Department of Water contract to monitor Swan coastal plain wetlands for the past 17 years, said the Gnangara mound had been "dramatically overextended" and the effects were being seen in wetlands. 

 

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He said wetlands were "surface expressions" of groundwater and as they dried reactions in the sediments produced sulfuric acid and released toxic substances into the water table. 

Professor Horwitz said wetlands naturally accumulated sediment that usually stayed free from oxygen because it 

was underwater and formed acid sulfate soils ‐ a combination of iron and sulfur that was benign if kept moist and deoxygenated. 

"If you dry those sediments . . . what happens is that you expose these sediments to air, you convert iron pyrite to sulphate and iron and when you do that in the presence of water you generate sulfuric acid," he said. 

"Sulfuric acid can mobilise metals so that goes into the water table." 

Professor Horwitz, who is working with the Ramsar Convention on Wetlands and the World Health Organisation, said a range of heavy metals been detected at Perth wetlands. 

"In different places at different times, arsenic is a problem, cadmium can be a problem, nickel can be a problem, lead can be a problem," he said. 

"Aluminium and iron are less toxic but they can also be a problem for other reasons." 

Another issue with drying sediments was that they were susceptible to fire and there were several cases of wetlands on the Swan coastal plain burning for months. 

Professor Horwitz said a change in water level had caused acidification at several wetlands in the metropolitan area, including at Lake Gnangara and near housing developments in Stirling and Gwelup. 

He said more research was needed to determine how dangerous the toxic sediments were to health, though it was clear smoke from peat fires at affected wetlands could cause respiratory problems for firefighters and nearby residents. 

Professor Horwitz said acidification and the leaching of heavy metals at wetlands could be reversed by reinstating appropriate water levels. 

Herons Creek – sick workers and ASS?  

Excavations linked to the upgrade of the Pacific Highway in late March 2012, uncovered unknown materials that caused several workers to become overcome by noxious fumes. Initial reports were that acid sulfate soils were implicated in the toxic effects experienced. 

The site was at Herons Creek (just south of Port Macquarie) where a truck accident in 1980 had spilled a mixed load of chemicals, including organochlorine pesticides (DDT), sodium propionate (food preservative) and radioactive material.  Following the accident, some of those chemicals had subsequently been buried on‐site.  

Emergency crews at the Herons Creek site          Source: Port Macquarie News 

Over the weeks following the 2012 excavation work, reports emerged that the workers had noticed grey clay which had orange streaks developing on oxidation and hence in the initial stages of the investigation, acid sulfate soil was being linked to the worker’s health issues.  

Subsequent analysis indicated that the symptoms displayed by the sick workers were consistent with short‐term exposure to sodium propionate or propionic acid and that the workers would not suffer ongoing issues as a result. The sodium propionate interacted with surrounding clay and other organic material and after excavation / oxidation it exhibited visual characteristics consistent with acid sulfate soils. Testing of soil from the site showed that neither actual nor potential acid sulfate soils were present.  

A detailed summary of the event and the subsequent investigations can be found at these websites: 

http://www.rta.nsw.gov.au/roadprojects/projects/pac_hwy/hexham_port_macquarie/herons_creek/documents/herons_creek_preliminary_report_brian_gillian.pdf 

http://www.rta.nsw.gov.au/roadprojects/projects/pac_hwy/hexham_port_macquarie/herons_creek/documents/herons_creek_r03_contamination_assessment_june12_part1.pdf 

 

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Pine Rivers area ‐ acid sulfate soils mapping project 

Erin Porter, Moreton Bay Regional Council 

In mid‐2011, Moreton Bay Regional Council (MBRC) in partnership with officers from the Queensland Department of Environment and Resource Management, completed an acid sulfate soil mapping project within the Pine Rivers catchment in South East Queensland. The area had previously been mapped at 1:100 000, however more detailed mapping was required to support planning and land management. 

The survey covered 3086 hectares (ha) of Hays Inlet and the North and South Pine Rivers and is shown in Figure 1. The survey area is centred on Griffin/Mango Hill and extends from Rothwell in the north, south to Brendale and west to Petrie. While the Pine River is a predominantly tide dominated estuary system, the study area represents a range of estuary energy zones including flood‐tidal delta, central basin and bay‐head delta.  

 

Figure 1: Map extract ‐ Moreton Bay Regional Council Acid Sulfate Soils ‐ Pine Rivers Area  

 

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4Click here for access to a high resolution version of the above map 

Methodology 

The project followed the special ASS mapping methodology employed by the Queensland Acid Sulfate Soil Investigation Team (QASSIT). The accompanying 1:25 000 scale ASS map displays the depth to potential acid sulfate soil (PASS) and/or actual acid sulfate soil (AASS). Mapping was undertaken at 1:25 000 scale within 1700 ha, with the remaining 1386 ha being tidal lands unlikely to be disturbed, land unable to be accessed, and land subject to intensive disturbance (such as residential development, extractive industries and industrial land). 

Within the detailed survey area 86 boreholes were sampled to depths ranging from 0.8 m to 9.8 m (average depth of 3.6 m). Results from 30 boreholes constructed as part of previous 1:100 000 scale mapping were also reviewed, with selected samples from 19 boreholes re‐analysed. In all, 574 samples were analysed using SPOCAS or Chromium suite methods.  

Findings 

 

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ASS extend across the study area at varying depths and in a wide range of soil textures. Of the 3086 ha study area, 2340 ha was identified as likely to contain ASS. Of the 1700 ha subject to detailed mapping, 1057 ha were found to contain ASS, mostly within two metres of the surface. 

AASS were present in 690 ha mainly between Rothwell and Griffin, and were encountered mostly in the top 1m. Existing acidity levels of up to 0.64 % S (eq) were found; often within the upper 0.5 m of the soil profile. In some locations it is unclear whether AASS are naturally occurring or whether they result from human activities.  

Most of the AASS have PASS layers in the same or underlying horizon, meaning that further disturbance has the capacity to release more acid and heavy metals. PASS were present in 367 ha, with potential acidity levels of up to 3.77 % S present at various depths from the surface to greater than seven metres.  

Loams and sands were common towards the Pine River mouth, with coarse gravels common in the western higher energy environs of the North and South Pine Rivers. Sulfidic clays were found at depth around Griffin, near the junction of the North and South Pine Rivers, and in the creeks off the main river channels and estuaries.  

Figure 2: Moreton Bay Regional Council Acid Sulfate Soils ‐ Pine Rivers Area report 

This survey found a greater extent of ASS in comparison to the previous 1:100 000 scale mapping, indicating the benefits of finer scale mapping.  

These findings will greatly assist in planning and managing development in the mapped areas to help protect the environment, public health and local infrastructure. Results will be used for the planning and assessment of activities and development involving soil disturbance and drainage.  In particular, they will provide additional information for the planning, design and management of a number of large infrastructure projects planned for this area. 

A key recommendation was to avoid intensive soil disturbance in areas where ASS are close to the surface. Also a number of locations were identified as possible remediation sites following previous disturbance of ASS without appropriate management.  

For further information, please contact Erin Porter from MBRC on (07) 5433 2406 or 

 

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Erin.Porter@moretonbay.qld.gov.au, or contact Jon Walton from the Department of Natural Resources and Mines on (07) 5451 2205 or jonathan.walton@derm.qld.gov.au.  

Copies of the report, map, and accompanying data, including soil profile descriptions and laboratory analyses, are available online.  

Reference 

Walton, J.S, Manders J.A, Goulding KE (2011).  Moreton Bay Regional Council Acid Sulfate Soils ‐ Pine Rivers Area. Queensland Government, Australia. 

 

Introducing new acid sulfate soil concepts into the Australian Soil Classification (paper presented at the 3rd National ASS Conference) 

Powell, B., Fitzpatrick R., Sullivan L., Tulau M., Moreton R., Hill J.  

Since the publication of the Australian Soil Classification (ASC) by Isbell (1996), considerable new knowledge has accumulated on the nature and distribution of acid sulfate soils (ASS). In 2010 the National Committee for Acid Sulfate Soils (NatCASS) acknowledged the need to commence a process to have these new developments recognised and incorporated into the ASC. A sub‐committee has reviewed our existing understanding through the scientific literature and soil databases and recommended suitable new concepts be introduced into the ASC. 

New knowledge and understanding of ASS that could be usefully introduced include: 

• the development of reliable standardised soil tests that can more accurately measure the abundance of iron sulfides and net acidity, 

• the identification of a wide range of diagnostic minerals indicative of sulfuric material, 

• the recognition and ready detection of hazardous monosulfidic material, 

• the recognition that sediments in shallow water environments undergo soil forming processes and meet the definition of pedological organisation used in the ASC, 

• the recognition of ASS in a wide variety of inland settings, 

• the observation that ceramic‐like soil materials can form following high temperature peat fires, and 

• the identification of iron sulfides in the bleached A2 and B horizons of some Aquic Podosols.  

Any proposed amendments need to be guided by the ten principles specified in the ASC. It should also be emphasised that no classification scheme is ever complete. As knowledge increases, there must be future modifications to the ASC to incorporate this new knowledge. 

The following new definitions are proposed for the Anthroposols, Organosols, Podosols, Vertosols, Hydrosols and Rudosols ASC soil orders. Many of the concepts are drawn from Sullivan et al. (2010), who have argued that existing definitions are inadequate and propose revisions for incorporation into national and international soil classifications. Significantly, these revisions have recently been trialled in the Murray‐Darling Basin (MDBA 2010). Consequently, it is proposed that Sulfidic be amended in the ASC by the new concepts below. These may be in combination if both materials occur within the one profile: 

• Sulfidic: material containing ≥ 0.01% sulfidic S.  

• Hypersulfidic: Sulfidic material that is capable of severe acidification as a result of oxidation of contained sulfides. 

 

 

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%SCR 

SCR 0.017 

0.015 

  

 

• Hyposulfidic: Sulfidic material that is not capable of severe acidification as a result of oxidation of contained sulfides. 

  

Hyposulfidic 

HHyyppeerrssuullffiiddiicc  PPooddoossooll  ((LL..  PPeessjjaakk,,  22001111))  

  

• Monosulfidic: material containing detectable monosulfides (≥ 0.01% acid volatile sulfide). 

• Sulfuric material: The term sulfuric material (Isbell 1996) remains conceptually unchanged from present usage. However, modifications to the definition by Fanning and Rabenhorst (2008) are proposed together with supporting evidence from recently published information in Australia. 

 

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• Fusic soil materials: Ceramic – like soil materials formed following high temperature peat fires.  

 

 

 

 Fusic soil material 

 

 

• Subaqueous soils: Soils that form in sediment found in shallow permanently flooded environments.  

 

• Subtidal soils: Subaqueous soils that form in tidal waters and are located between low tide and 2.5m below low tide. 

 

 

 

 

 

 

 

 

 

 

 

Subaqueous soil environment  Subtidal soil environment  

 

We believe the introduction of these new concepts will enhance the ASC by defining the various forms of ASS materials that are now known to exist in Australia. 

References Fanning, D.S. and Rabenhorst M.C. (2008). Rationale for updating the definitions of Sulfidic Materials and the Sulfuric Horizon in Soil Taxonomy and proposed revised definitions. In C Lin, S Huang and Y Li. (Ed.) Proceedings of the Joint Conference of the 6th International Symposium in Acid Sulfate Soil Conference and the Acid Rock Drainage Symposium. Guangzhou, China, Sep 16‐20, 2008. Guangdong Science & Technology Press, Guangzhou, P.R. China. 53 – 61. 

Isbell, R.F., (1996). The Australian Soil Classification. CSIRO Publishing, Melbourne, Australia. 

MDBA (2010) Detailed Assessment of Acid Sulfate Soils in the Murray‐Darling Basin: Protocols for sampling, field characterisation, laboratory analysis and data presentation. Murray–Darling Basin Authority. MDBA Publication 57/10. ISBN 978‐1‐921557‐67‐5. 58 pp. 

Sullivan, L.A., Fitzpatrick, R.W., Bush, R.T., Burton, E.D., Shand, P., and Ward, N.J. (2010). The classification of acid sulfate soil materials: further modifications. Southern Cross GeoScience  Technical Report No. 310. Southern Cross University, Lismore, NSW, Australia. 

  

 

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Review of ASS disposal in WA 

Clare Nixon, DEC 

A review in Western Australia has found that most excavated acid sulfate soil (ASS) materials are being treated and reused on development sites.  

ASS closure reports, submitted to the Department of Environment and Conservation (DEC) for clearance of planning conditions, include details on how developers dispose of any ASS materials excavated from their sites. 

DEC’s Stephen Wong said by reviewing ASS closure reports (2010‐2011), they were able to determine that in most cases, ASS excavated during urban land development were treated and re‐used on site.  

“ASS disposal to landfill across the Perth metropolitan area and Swan Coastal Plain accounts for a very small percentage of ASS disposal,” he said.  

“And disposing of ASS to a licensed soil‐blending facility or landfill is only considered when it is considered unsuitable for reuse.” 

The closure reports revealed that 94% of excavated ASS required lime treatment and 89% of that was either reused on‐site or offsite following treatment. A much smaller percentage (6%) was transported to soil blending facilities or disposed of at approved landfills (5%). 

Stephen said it was likely that transportation and disposal fees were keeping excavated ASS materials out of landfills.  

“With more and more development occurring in areas underlain by acid sulfate soils, it is imperative to properly manage and monitor the disposal of ASS,” he said. 

“Historically, ASS disturbance was not a significant issue in the Perth metropolitan region and Swan Coastal Plain as most development took place in dry areas with deep water tables where there was a low risk of encountering ASS materials.”  

“However, as good quality urban land becomes scarce and waterside development increasingly popular, the excavation and disposal of ASS during development is becoming a significant management issue.”            

                Summary of ASS reuse and disposal options during 2010‐2011 

 

 

 

 

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A novel approach to removal of pyritic sediment from a constructed stormwater treatment wetland in Western Australia 

Peter Adkins, Swan River Trust 

 

The Liege Street Stormwater Treatment Wetland (1 ha) was constructed in 2004 and is located in Cannington, approximately 10 kilometres south‐east of the Perth CBD. The wetland receives runoff from a 530ha catchment, with mainly commercial / residential land use. It was designed to improve stormwater quality from summer / autumn storm events, prior to discharge into the Canning River. The wetland is located in the Canning River Regional Park and therefore protection and enhancement of habitat values was seen as a critical component during planning and implementation of this project. 

Initially the wetland performed well, reducing nutrients and other pollutants from stormwater flows. However, since its construction, macrophyte coverage in wetland areas has reduced by more than 70%, significantly impacting the wetlands ability to improve water quality.  

High organic and nutrient loading derived from inflows, combined with locally available sulfate and iron under permanently inundated highly reducing conditions, have caused the development of pyritic sediments which have led to the decline in macrophyte coverage across the wetland.  

To remedy this issue, the pyritic sediments were removed from the wetland using a Micro‐dredge and Geopro Desludging Tubes (Figures 1 and 2). Owned and operated by Apex Envirocare, the Micro‐dredge is a compact dredge (6.4 x 1.8m) that is launched from a trailer. The Micro‐dredge can pump at a rate of 6,800L/min, operating in as little as 400mm of water, and is driven by a double‐pulley hydraulic windlass with two hydraulic motors. The suction cutter head is 1.65m x 0.36m and can dredge up to a depth of 5m. 

   

Figure 1. Micro‐dredge in operation    Figure 2. Desludging tubes 

The use of the Micro‐dredge and desludging tubes, assisted by earthmoving plant, allowed removal of approximately 200 tonnes (dry weight) of pyritic sediment from the wetland, so that the sediment could be dried and treated in an adjacent limestone bunded area with a relatively small foot print, limiting impacts on the existing vegetation.  

Initially, the Micro‐dredge only removed a portion of the pyritic sediment with a significant volume of sediment remaining due to underwater obstructions that limited access. Irregular shaped wetland areas also restricted the Micro‐dredge reach due to the location of its guide wires. The water column in the vicinity of the dredge was quite turbid during dredging, which would have added to the volume of sediment left in the wetland once these fines settled. 

 

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Following the initial dredge, the Micro‐dredge returned to the wetland to remove the remaining sediment which had been moved by earth moving plant into more accessible deeper ponds in the wetland. The movement of this sediment was facilitated by the planned spreading of sand on the wetland base, to decrease sumpland depths.  

Unfortunately, some of this sand mixed into the sediment, causing frequent blockages in the dredge pipework, limiting the volume of material the dredge could effectively remove. The sand also reduced the efficiency of the desludging tubes at removing fines, as sand settled at the inlet of the tubes, forming a mound as can be seen in Figure 2. Dredge effluent sprayed off this mound resulting in turbid water exiting the tubes, until the tubes were inflated higher than the mound negating this issue. 

Although the Micro‐dredge is small and manoeuvrable in a limited area, which may suit other projects quite effectively, the non‐geometric shapes of the wetland and the introduced sand did not suit this approach; however dredged sediment was removed wet, which was critical in avoiding oxidation of the pyritic sediment.  

The use of in‐line coagulant dosing followed by discharge into the desludging tubes was a very successful way to dewater the dredged sediment in a limited area, although the sand component in the dredge material did cause issues with water quality released from the tubes. When there was no sand in the dredge material and the tubes were able to release water without interference from the sand mound, the tubes only released a small quantity of fines with an internal layer of sediment quickly developing. This internal layer of sediment provided a secondary filtering mechanism, returning water that was clear of fines and, which after it had passed through the limestone bunded storage area, was of a suitable quality to discharge back into the wetland (Figure 3).  

The initial dredging took place over the late summer period. The desludging tubes developed a substantial biofilm cover likely assisting their water quality improvement function (Figure 4). 

          

Figure 3. Dredge effluent pre and post dosing         Figure 4. Biofilm on desludging tubes   

 

Although pyritic sediment still remains submerged in some of the deeper ponds of the wetland, removal of this material from the wetland sumplands, combined with decreased sumpland depths and changes to operational water levels will allow the wetland to seasonally dry‐out in certain areas. These changes, combined with planting of tubestock, will promote vegetative growth, improving wetland function and discouraging the accumulation of pyritic sediments in vegetated areas of the wetland, which will also reduce the frequency and possibly the need for similar future maintenance activities.  

For further information regarding this article, please contact: peter.adkins@swanrivertrust.wa.gov.au  

 

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2012 Acid sulfate soil short course program 

Chrisy Clay, Southern Cross GeoScience 

Southern Cross GeoScience is continuing to roll out its highly successful acid sulfate soil short course program during 2012.  The courses, which have been delivered at least once in every state and territory, will be now run on an as‐needs‐basis.   

The course, which covers how to manage acid sulfate soils during development, has been specifically developed for consultants, engineers, contractors, environmental officers and town planners.  Developed in conjunction with the relevant regulatory authorities in each jurisdiction, the course is state‐specific and adapted to suit the legislative framework and unique acid sulfate soil characteristics of each state or territory. 

 

Organisers have found that even experienced practitioners, who have been working in the field for some years, are improving their knowledge, skills and confidence by attending the course.  In particular participants are interested in further information on the analysis of acid sulfate soils and how to interpret laboratory results.  This, as well as, conducting a desktop and preliminary assessment, identifying suitable management options and writing a management plan are all covered during the course.   

 

People interested in attending the short course are encouraged to visit Southern Cross GeoScience’s website http://www.scu.edu.au/geoscience/index.php/15/ and register their expression of interest with the organiser, Chrisy Clay chrisy.clay@scu.edu.au  

Upcoming courses in 2012 include: 17 & 18 July ‐ Perth WA (course is fully booked) as well as repeat courses in Queensland and Perth later in the year.  

 

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Latest publications 

 Amaral V.  Thompson EL.  Bishop MJ.  Raftos DA. (2012). The proteomes of Sydney rock oysters vary spatially according to exposure to acid sulfate runoff. Marine & Freshwater Research. 63(4):361‐369.  Runoff from acid sulfate soils (ASS) has severe environmental and economic impacts on estuarine ecosystems.

Oysters display reduced abundance, growth rate and shell thickness when exposed to ASS runoff, yet the molecular

underpinnings of their responses have not been explored.

We hypothesised that the proteomes of wild Sydney rock oysters, Saccostrea glomerata, would differ between

populations recurrently exposed to ASS compared with those unaffected by runoff from ASS. We used two-

dimensional electrophoresis to compare protein abundances in the gills of S. glomerata collected from two sites

close to (acidified) and two sites away from (reference) major ASS outflow drains in a south-east Australian

estuary.

Approximately 5% of the proteome was differentially expressed between oysters from acidified and reference

sites, with five protein spots more abundant and one less abundant at the sites close to drains. Another protein

spot was present only in oysters from reference sites.

This study is the first screening of spatial variation in the protein expression of S. glomerata with respect to

discharge from ASS. Altered protein expression may underpin short-term inducible responses to ASS runoff, or

genetic resistance acquired through recurrent exposure of populations to the stressor.

Boys CA. Rowland SJ. Gabor M. Gabor L. Marsh IB. Hum S. Callinan RB. (2012). Emergence of Epizootic Ulcerative Syndrome in native fish of the Murray‐Darling river system, Australia: Hosts, distribution and possible vectors. PLoS ONE 7(4): e35568. doi:10.1371/journal.pone.0035568 

Epizootic ulcerative syndrome (EUS) is a fish disease of international significance and reportable to the Office

International des Epizootics. In June 2010, bony herring Nematalosa erebi, golden perch Macquaria ambigua,

Murray cod Maccullochella peelii and spangled perch Leiopotherapon unicolor with severe ulcers were sampled

from the Murray-Darling River System (MDRS) between Bourke and Brewarrina, New South Wales Australia.

Histopathology and polymerase chain reaction identified the fungus-like oomycete Aphanomyces invadans, the

causative agent of EUS. Apart from one previous record in N. erebi, EUS has been recorded in the wild only from

coastal drainages in Australia. This study is the first published account of A. invadans in the wild fish populations

of the MDRS, and is the first confirmed record of EUS in M. ambigua, M. peelii and L. unicolor.

Ulcerated carp Cyprinus carpio collected at the time of the same epizootic were not found to be infected by EUS,

supporting previous accounts of resistance against the disease by this species. The lack of previous clinical

evidence, the large number of new hosts (n = 3), the geographic extent (200 km) of this epizootic, the severity of

ulceration and apparent high pathogenicity suggest a relatively recent invasion by A. invadans.

The epizootic and associated environmental factors are documented and discussed within the context of possible

vectors for its entry into the MDRS and recommendations regarding continued surveillance, research and

biosecurity are made.

 

 

 

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Fraser MA.  Baldwin DS.  Rees GN.  Silvester EJ.  Whitworth KL. (2012). Rehabilitation options for inland waterways impacted by sulfidic sediments ‐ Field trials in a south‐eastern Australian wetland. Journal of Environmental Management. 102:71‐78. 

The accumulation of significant pools of sulfidic sediments in inland wetlands and creeks is an emerging risk for

the management of inland waterways. We used replicated plot trials to appraise the viability of various strategies

for neutralizing oxidized, acidified sulfidic sediments in a highly degraded wetland.

Of the twenty different treatments trialed only addition of calcium hydroxide or calcium carbonate, burning of

wood, and planting of Phragmites australis, Typha domingensis and Atriplex nummularia into beds prepared with

CaCO3 or P. australis and T. domingensis into beds of sediment and mulch, decreased total actual acidity (TAA) in

the top 5 cm of sediment in the first two weeks following treatment. Only the calcium hydroxide treatments and

planting of P. australis, T. domingensis and A. nummularia into beds prepared with CaCO3 decreased TAA for a

longer period of time (6 months). None of the treatments, except the planting of P. australis into beds prepared

with lime, decreased TAA in the 5-30 cm layer of sediments. Therefore, the only effective treatment appears to be

the application of highly alkaline ameliorants which need to be transported to the site.

A survey of the wetland was undertaken to estimate the total amount of actual and potential acidity stored in the

wetland's sediment and overlying water and showed that up to 1200 tonnes of calcium carbonate would be

required to neutralise all of the actual and potential acidity in the 10 ha wetland.

However, neutralisation of the remaining water in the wetland (about 12.5 ML) would produce approximately 2750

m3 of metal rich sludge (approximately 100 tonnes dry weight) that would require separate disposal.

Johnston SG.  Keene AF.  Burton ED.  Bush RT.  Sullivan LA. (2012). Quantifying alkalinity generating processes in a tidally remediating acidic wetland. Chemical Geology. 304:106‐116. 

Lime-assisted tidal exchange (LATE) is a new remediation technique that is demonstrably effective at decreasing

acidity in coastal acid sulfate soils (CASS).

However, the relative magnitude of the major in situ alkalinity generating processes and external alkalinity inputs

that dominate neutralization of acidity during LATE have not been quantified. Here, we combine investigations of

porewater and solid-phase geochemistry from a remediating CASS wetland to derive first-order estimates of

alkalinity generating processes and inputs after 6 years of LATE. Quantified inputs include: marine derived HCO3-

from tidal exchange; hydrated lime additions; and in situ alkalinity from anaerobic metabolism of organic carbon

coupled with reduction of iron and sulfate.

A progressive increase in tidal inundation led to the development of significant relationships (alpha = 0.01)

between topography and both non-sulfidic. solid-phase Fe(II) and solid-phase reduced inorganic sulfur species.

These topographic relationships were conjoined with a digital elevation model, enabling up-scaling of alkalinity

estimates to a sub-catchment level. Estimates indicate the relative order of importance of alkalinity generating

processes and inputs is Fe reduction (50-64%) > tidal exchange (25-42%) > sulfate reduction (7-13%) >> hydrated

lime addition (< 1%).

Accurately attributing the relative contributions due to Fe and SO42- reduction was limited by an inability to

distinguish between non-sulfidic, solid-phase Fe(II) generated by microbial dissimilatory reduction of Fe(III) or

chemical reduction of Fe(III) by H2S. Nevertheless, the combined alkalinity contribution of these two electron

accepting processes accounts for between 58 and 74% of the total. The majority (> 99%) of net alkalinity

generation was due to either tides or microbial metabolism.

This indicates that the LATE remediation technique is both a cost effective means of decreasing soil acidity and is

readily transferable to similar CASS landscapes - provided there is adequate supply of suitable electron donors and

 

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sufficient regenerative capacity in the adjacent estuarine/marine tidal HCO3- pool.

Morgan B.  Rate AW.  Burton ED.  Smirk MN. (2012). Enrichment and fractionation of rare earth elements in FeS‐ and organic‐rich estuarine sediments receiving acid sulfate soil drainage. Chemical Geology. 308:60‐73. 

An understanding of processes controlling the behaviour of rare earth elements (REEs) within estuarine sediments

is essential for the effective use of REEs as tracers of environmental conditions.

This study investigates the enrichment and fractionation of REEs in sediments with abundant iron monosulfides

(FeS, measured as acid-volatile sulfide, median = 156 mu mol/g) and organic carbon (median = 3.2 mmol/g). We

examined sediments collected from a eutrophic estuary in Western Australia, which comprised several sedimentary

environments, including sites receiving drainage from acid sulfate soils (ASS).

In general, sediment-bound REEs were highly soluble in HCl, with 1 mol/L HCl extractable REE concentrations

amounting to >80% of corresponding total concentrations in approximately 70% of samples. A mid-REE (MREE)

enrichment was consistently apparent in all sediment samples, with a median MREE enrichment value of 1.30

(range = 1.13-1.50) for the total REE concentrations and 1.26 (range = 1.17-1.44) in the 1 mol/L HCl extractions.

Also, a Ce anomaly was consistently observed in the sediments examined here, with a median value of 1.11 (range

= 0.79-1.58) for the total REE concentrations and 1.19 (range = 1.04-1.71) in the 1 mol/L HCI extracts. In general,

a minor depletion of heavy-REEs (HREEs) relative to light-REEs (LREEs) was also apparent in many of the sediments

(Yb/La<1).

This actionation trend, in addition to a strong positive correlation between the MREE enrichments and Yb/La

ratios, is consistent with sediment organic matter acting as a REE host phase. Abundant sedimentary FeS was also

hypothesised to have influenced REE behaviour in the field, based on the high proportion of total REEs extracted

by 1 mol/L HCl, as well as strong correlations between total REE concentrations and both total Fe and total S in

the sediments examined here.

However, in our laboratory experiment we found that REEs exhibit little (or no) short-term sorptive affinity for

FeS, implying that if any FeS REE interactions were occurring, this must involve mechanisms other than rapid

sorption to pre-existing FeS. Sites receiving ASS drainage were unique in displaying (1) a strong relative enrichment

of total REE concentrations in comparison to non-impacted sites, and (2) a significant positive correlation between

the magnitude of the positive Ce anomalies and the magnitude of MREE enrichment.

This observation demonstrates the utility of REEs as tracers of anthropogenic influences (especially the influence

of ASS drainage) in FeS- and organic-rich estuarine sediments.

 

Nyberg ME.  Osterholm P.  Nystrand MI. (2012). Impact of acid sulfate soils on the geochemistry of rivers in south‐western Finland. Environmental Earth Sciences. 66(1):157‐168. 

Large areas of acid sulfate (AS) soils are located along the coastal plains of Finland, and previous studies have

shown that after reclamation they release extreme quantities of metals to watercourses in mid-western and

northern Finland.

In this study on streams of south-western Finland, where little information about AS soils is available, these soils

were found to exhibit the same pattern of elevated metal- and sulfate concentrations as in the notorious AS soil

landscapes of mid-western Finland. Meteorologically/hydrologically driven temporal variations of these elements

were great in the most affected streams.

 

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There were also significant positive implications regarding future environmental work; AS soils in the highlighted

region were found to cause sudden temporal influxes of acidic water only in the most affected streams, indicating

that the overburden and soils of the area discharge well buffered water. Moreover, it was indicated that the high

(less toxic) metal concentrations are largely caused by erosion of suspended phyllosilicates (< 0.45 mu m) from

farmland rather than by AS soils. 

 

Nystrand MI.  Osterholm P.  Nyberg ME.  Gustafsson JP. (2012) Metal speciation in rivers affected by enhanced soil erosion and acidity. Applied Geochemistry. 27(4):906‐916. 

Dissolved (<1 kDa), colloidal (1 kDa-0.45 mu m) and particulate (>0.45 mu m) size fractions of 30 elements were

determined for four rivers (Sirppujoki, Laajoki, Mynajoki and Paimionjoki), including 12 low-order inflow streams,

largely affected by soil erosion and acidity in SW Finland. In addition, geochemical modelling was used to predict

the formation of free ions and complexes in these rivers.

Total metal concentrations were relatively high but most of the elements occurred mainly in a colloidal or

particulate form and even elements expected to be very soluble occurred to a large extent in colloidal form.

According to geochemical modelling these patterns could be explained by in-stream metal

complexation/adsorption only to a limited extent. Instead there were strong indications that the high metal

concentrations and dominant solid fractions were largely caused by erosion of metal bearing phyllosilicates.

A strong influence of acid sulphate (AS) soils, known to exist in the catchment, could be clearly distinguished in

Sirppujoki river as it had very high concentrations of dissolved metals, while in the two nearby rivers (Laajoki and

Myna joki) the influence of AS soils was largely masked by eroded phyllosilicates. In Paimionjoki river the colloidal

and particulate fractions dominated very strongly, indicating that total metal concentrations are almost solely

controlled by erosion of phyllosilicates.

Consequently, rivers draining clay plains sensitive to erosion, like those in SW Finland, have generally high

"background'' metal concentrations due to erosion of relatively non-toxic colloidal/particulate phyllosilicates.

Thus, relying on only semi-dissolved (<0.45 mu m) concentrations obtained in routine monitoring and/or speciation

modelling can lead to a great overestimation of the water toxicity in this environment.

Prakongkep N.  Gilkes RJ.  Singh B.  Wong S. (2012). Pyrite and other sulphur minerals in giant aquic spodosols, Western  Australia. Geoderma. 181:78‐90. 

Thirty very deep aquic spodosols in swales of the Bassendean Dune System, Western Australia were investigated for

their potential to acidify due to their contents of acid-forming sulphur minerals.

Pyrite commonly occurs in B, Bh, C and sometimes A and E horizons of these soils. Two morphologies of pyrite are

present: single crystals of pyrite are euhedral cubic or octahedral (<= 1 mu m) and framboidal pyrite aggregate

grains range from 1 to 10 mu m. Elemental sulphur in the form of anhedral particles 10-500 nm may occur in E, B

and Bh horizons and is strongly associated with organic matter and jarosite sometimes occurred in the A horizon.

Rare marcasite and mackinawite are other acid generating sulphide minerals and indicate the diverse redox and

other chemical conditions that exist in these spodosols. Consequently drying and aeration of these soils due to

drainage and possibly also to climate change acidifies both soil and groundwater. These spodosols are therefore

acid sulphate soils. Acid buffering is mostly minor and is provided by organic matter and allophane.

These observations of acid generating sulphides in spodosols may indicate that very acid nonaquic spodosols

elsewhere were once saturated and contained pyrite before the profiles experienced permanent or episodic

oxidising conditions.

 

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Schumann R.  Stewart W.  Miller S.  Kawashima N.  Li J.  Smart R. (2012). Acid‐base accounting assessment of mine wastes using the chromium reducible sulfur method. Science of the Total Environment. 424:289‐296. 

The acid base account (ABA), commonly used in assessment of mine waste materials, relies in part on calculation

of potential acidity from total sulfur measurements. However, potential acidity is overestimated where organic

sulfur, sulfate sulfur and some sulfide compounds make up a substantial portion of the sulfur content.

The chromium reducible sulfur (CRS) method has been widely applied to assess reduced inorganic sulfur forms in

sediments and acid sulfate soils, but not in ABA assessment of mine wastes. This paper reports the application of

the CRS method to measuring forms of sulfur commonly found in mine waste materials.

A number of individual sulfur containing minerals and real waste materials were analyzed using both CRS and total

S and the potential acidity estimates were compared with actual acidity measured from net acid generation tests

and column leach tests. The results of the CRS analysis made on individual minerals demonstrate good assessment

of sulfur from a range of sulfides. No sulfur was measured using the CRS method in a number of sulfate salts,

including jarosite and melanterite typically found in weathered waste rocks, or from dibenzothiophene

characteristic of organic sulfur compounds common to coal wastes.

Comparison of ABA values for a number of coal waste samples demonstrated much better agreement of acidity

predicted from CRS analysis than total S analysis with actual acidity. It also resulted in reclassification of most

samples tested from PAF to NAF. Similar comparisons on base metal sulfide wastes generally resulted in

overestimation of the acid potential by total S and underestimation of the acid potential by CRS in comparison to

acidity measured during NAG tests, but did not generally result in reclassification. In all the cases examined, the

best estimate of potential acidity included acidity calculated from both CRS and jarositic S.

Whitworth KL. Baldwin DS. Kerr JL. (2012). Drought, floods and water quality: Drivers of a severe hypoxic blackwater event in a major river system (the southern Murray–Darling Basin, Australia). Journal of Hydrology. 450–451 (2012): 190–198. 

Hypoxic blackwater events are characterised by high levels of dissolved organic carbon in the water column,

the metabolism of which depletes dissolved oxygen, which can cause fish and crustacean mortality.

Understanding the drivers of and controls on hypoxic blackwater events is important in order to reduce

the potential for detrimental water quality impacts from both managed and natural flows.

After a decade long drought in south-eastern Australia, a series of spring and summer flood events in 2010–2011

resulted in a large-scale hypoxic blackwater event in the southern Murray–Darling Basin that affected

over 2000 km of river channels and persisted for 6 months. We examined the biogeochemistry and

hydrology underpinning this extreme event and found that multiple drivers contributed to the development

and persistence of hypoxic blackwater.

Inundation of both forested and agricultural floodplains that had not been flooded for over a decade mobilised

large stores of reactive carbon. Altered flow seasonality, due to a combination of climatic effects and river

regulation, not only increased the risk of hypoxic blackwater generation but also shifted the proportion of

bioavailable carbon that was returned to the river channels. Hypolimnetic weir discharge also contributed to

hypoxia at some sites.

These findings highlight the need for a whole-of-system perspective for the management of regulated river

systems – especially in the face of a changing climate.

 

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ASSAY is a free, quarterly newsletter about acid sulfate soils around Australia, and is available to all people interested in this issue. 

It is produced by NSW Department of Primary Industries with joint funding assistance from the Federal, State and Territory governments. 

To subscribe, simply email the editor with “Subscribe ASSAY” in the subject line: 

simon.walsh@dpi.nsw.gov.au

Conferences and workshops  

7th International Acid Sulfate Soil Conference  

 

 

Theme: “Towards Harmony between Land Use and Environment”. 

Conference:     August 26 ‐ 30  Excursions:     August 31 – September 1  

 

2nd Circular and call for abstracts: 

http://projects.gtk.fi/export/sites/projects/7iassc/2nd_Circular7IASSC.pdf  

Registration:  

Those interested in participation are kindly requested to register on‐line (open from December 2011) via 7th IASSC webpage, www.7iassc.fi.  

 

ASSAY contact details  

Previous issues of ASSAY are available from: http://www.dpi.nsw.gov.au/aboutus/resources/periodicals/newsletters/assay/