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Full-Text Articles in Soil Science
Hydro-Geochemical Coupling In Seawater Inundation Acid Sulfate Soils: Mobilisation Of Arsenic And Hysteresis In Iron And Sulfur Cycling, Scott Johnston, Annabelle Keene, Edward Burton, Richard Bush, Leigh Sullivan
Hydro-Geochemical Coupling In Seawater Inundation Acid Sulfate Soils: Mobilisation Of Arsenic And Hysteresis In Iron And Sulfur Cycling, Scott Johnston, Annabelle Keene, Edward Burton, Richard Bush, Leigh Sullivan
Associate Professor Edward D Burton
A large-scale field trial indicates that tidal seawater inundation of coastal acid sulfate soils (CASS) stimulates iron and sulfate reducing conditions, leading to the generation of internal alkalinity and greatly decreasing soil / groundwater acidity. This remediation technique can be considered highly effective from the relatively narrow perspective of decreasing acidity and raising pH. However, a broader perspective reveals that tidal seawater inundation initiates complex and tightly coupled hydrological and geochemical processes within sediments and porewaters. These processes have had a profound effect on the mobilisation, redistribution and transformation of Fe minerals in the landscape (Johnston et al., 2011a) – …
Arsenic Mobilization And Iron Transformations During Sulfidization Of As(V)-Bearing Jarosite, Scott Johnston, Edward Burton, Annabelle Keene, Britta Planer-Friedrich, Andreas Voegelin, Mark Blackford, Greg Lumpkin
Arsenic Mobilization And Iron Transformations During Sulfidization Of As(V)-Bearing Jarosite, Scott Johnston, Edward Burton, Annabelle Keene, Britta Planer-Friedrich, Andreas Voegelin, Mark Blackford, Greg Lumpkin
Associate Professor Edward D Burton
Jarosite (KFe3(SO4) 2(OH)6) is an important host-phase for As in acid mine drainage (AMD) environments and coastal acid sulfate soils (CASS). In AMD and CASS wetlands, jarosite may encounter S(−II) produced by sulfate reducing bacteria. Here, we examine abiotic sulfidization of As(V)-bearing K-jarosite at pH 4.0, 5.0, 6.5 and 8.0. We quantify the mobilization and speciation of As and identify corresponding Fe mineral transformations. Sulfide-promoted dissolution of jarosite caused release of co-precipitated As and the majority of mobilized As was re-partitioned to a readily exchangeable surface complex (AsEx). In general, maximum As mobilization occurred in the highly sulfidized end-members of …
Seawater Inundation Of Fe-Rich Coastal Lowlands – Hydrogeochemical Coupling And Hysteresis At The Tidal Fringe, Scott Johnston, Annabelle Keene, Richard Bush, Edward Burton, Leigh Sullivan
Seawater Inundation Of Fe-Rich Coastal Lowlands – Hydrogeochemical Coupling And Hysteresis At The Tidal Fringe, Scott Johnston, Annabelle Keene, Richard Bush, Edward Burton, Leigh Sullivan
Associate Professor Edward D Burton
Over 17 million ha of coastal lowlands contain acid sulfate soils (CASS). These soils are rich in meta-stable, redoxsensitive Fe (III)-minerals. Large areas of CASS are at risk of increased saline tidal inundation due to sea-level rise. Fieldbased CASS remediation trials reveal that tidal seawater inundation initiates radical changes in sediment hydrogeochemistry, stimulating Fe and SO4 reducing conditions, generating alkalinity and greatly decreasing the acidity hazard. However, these changes also have profound consequences for the fate, mobilisation, redistribution and transformation of Fe minerals and co-associated trace elements. Here, we examine the consequences for iron and arsenic by investigating the hydrology, …
Climate Change Impacts On Acid Sulfate Soil Landscapes, Richard Bush, Leigh Sullivan, Edward Burton, Scott Johnston, Annabelle Keene, Vanessa Wong, L Mosley
Climate Change Impacts On Acid Sulfate Soil Landscapes, Richard Bush, Leigh Sullivan, Edward Burton, Scott Johnston, Annabelle Keene, Vanessa Wong, L Mosley
Associate Professor Edward D Burton
The anticipated impacts of climate change are warmer conditions, an increasing proportion of rainfall to occur from heavy falls, increasing occurrence of drought in many regions, increasing frequency of intense tropical cyclones, rising sea levels and frequency of extreme high seas (e.g. storm surges). All of these predicted impacts have direct relevance to coastal acid sulfate soils landscapes, through either exacerbating sulfide oxidation by drought, re-instating reductive geochemical processes or changing the export and mobilisation of contaminants. The interaction of specific land management factors such as man-made drainage will also have a significant role in how the predicted impacts of …
Impacts Of Sea Level Rise On The Biogeochemistry Of A Coastal Floodplain In Eastern Australia, Vanessa Wong, Phillip Hirst, Scott Johnston, Richard Bush, Leigh Sullivan, Edward Burton, P Slavich
Impacts Of Sea Level Rise On The Biogeochemistry Of A Coastal Floodplain In Eastern Australia, Vanessa Wong, Phillip Hirst, Scott Johnston, Richard Bush, Leigh Sullivan, Edward Burton, P Slavich
Associate Professor Edward D Burton
No abstract provided.
Evaluation Of Existing Methods For Assessing Retained Acidity In Acid Sulfate Soil Materials, C Vithana, Leigh Sullivan, Richard Bush, Edward Burton, Scott Johnston
Evaluation Of Existing Methods For Assessing Retained Acidity In Acid Sulfate Soil Materials, C Vithana, Leigh Sullivan, Richard Bush, Edward Burton, Scott Johnston
Associate Professor Edward D Burton
No abstract provided.
Mobilisation Of Arsenic Following Sea-Water Inundation Of Acid Sulfate Soils, Scott Johnston, Annabelle Keene, Richard Bush, Edward Burton, Leigh Sullivan
Mobilisation Of Arsenic Following Sea-Water Inundation Of Acid Sulfate Soils, Scott Johnston, Annabelle Keene, Richard Bush, Edward Burton, Leigh Sullivan
Associate Professor Edward D Burton
No abstract provided.
Reductive Dissolution Of Natural Jarosite In A Tidally Inundated Acid Sulfate Soil: Geochemical Implications, Annabelle Keene, Scott Johnston, Richard Bush, Leigh Sullivan, Edward Burton
Reductive Dissolution Of Natural Jarosite In A Tidally Inundated Acid Sulfate Soil: Geochemical Implications, Annabelle Keene, Scott Johnston, Richard Bush, Leigh Sullivan, Edward Burton
Associate Professor Edward D Burton
No abstract provided.
Effectiveness Of Lime Particle Size In The Neutralisation Of Sulfidic Acid Sulfate Soil Materials, Kim Watling, Angus Mcelnea, Colin Ahern, Edward Burton, Scott Johnston, Annabelle Keene, Richard Bush, Leigh Sullivan
Effectiveness Of Lime Particle Size In The Neutralisation Of Sulfidic Acid Sulfate Soil Materials, Kim Watling, Angus Mcelnea, Colin Ahern, Edward Burton, Scott Johnston, Annabelle Keene, Richard Bush, Leigh Sullivan
Associate Professor Edward D Burton
No abstract provided.
Sulfidisation Processes In A Reactive Fe-Enriched Acid Sulfate Soil, Northeastern Australia, Annabelle Keene, Scott Johnston, Richard Bush, Leigh Sullivan, Edward Burton
Sulfidisation Processes In A Reactive Fe-Enriched Acid Sulfate Soil, Northeastern Australia, Annabelle Keene, Scott Johnston, Richard Bush, Leigh Sullivan, Edward Burton
Associate Professor Edward D Burton
No abstract provided.
Remediating Coastal Acid Sulfate Soils By Tidal Inundation: Geochemical Hysteresis Of Iron, Scott Johnston, Annabelle Keene, Richard Bush, Edward Burton, Leigh Sullivan
Remediating Coastal Acid Sulfate Soils By Tidal Inundation: Geochemical Hysteresis Of Iron, Scott Johnston, Annabelle Keene, Richard Bush, Edward Burton, Leigh Sullivan
Associate Professor Edward D Burton
No abstract provided.
Catalytic Action Of Aqueous Ferrous Iron And Sulfide On The Transformation Of Iron Oxides In Acid Sulfate Soils, Richard Bush, Edward Burton, Leigh Sullivan, Scott Johnston
Catalytic Action Of Aqueous Ferrous Iron And Sulfide On The Transformation Of Iron Oxides In Acid Sulfate Soils, Richard Bush, Edward Burton, Leigh Sullivan, Scott Johnston
Associate Professor Edward D Burton
No abstract provided.
Remediation Of Coastal Acid Sulfate Soils By Tidal Inundation: Effectiveness And Geochemical Implications, Scott Johnston, Annabelle Keene, Richard Bush, Edward Burton, Leigh Sullivan
Remediation Of Coastal Acid Sulfate Soils By Tidal Inundation: Effectiveness And Geochemical Implications, Scott Johnston, Annabelle Keene, Richard Bush, Edward Burton, Leigh Sullivan
Associate Professor Edward D Burton
The effects of restoring marine tidal inundation to a severely degraded acid sulfate soil landscape were investigated. Five years of regular tidal inundation led to substantial improvements in a range of key parameters used to assess soil and water quality. The pH of estuarine creeks improved dramatically following reintroduction of tidal inundation. Time series water quality and climatic data indicate a substantial decrease in the magnitude of creek acidification per given quantity of antecedent rainfall. The soil pH also increased by 2–3 units and titratable actual acidity (TAA) decreased by ~40–50 μmol H+ g-1 within former sulfuric horizons. Tidal inundation …
A National Demonstration Site For Innovative Acid Sulfate Soil Research, East Trinity, Scott Johnston, Richard Bush, Leigh Sullivan, Edward Burton, D Smith, Michelle Martens, Angus Mcelnea, Colin Ahern, Bernard Powell, Luisa Stephens, Steven Wilbraham, Simon Van Heel
A National Demonstration Site For Innovative Acid Sulfate Soil Research, East Trinity, Scott Johnston, Richard Bush, Leigh Sullivan, Edward Burton, D Smith, Michelle Martens, Angus Mcelnea, Colin Ahern, Bernard Powell, Luisa Stephens, Steven Wilbraham, Simon Van Heel
Associate Professor Edward D Burton
No abstract provided.
Accumulation Of Schwertmannite Impact On Water Quality In Acid Sulfate Soil Landscapes, Leigh Sullivan, Richard Bush, Edward Burton, Yasimin Cabot, Nadia Toppler
Accumulation Of Schwertmannite Impact On Water Quality In Acid Sulfate Soil Landscapes, Leigh Sullivan, Richard Bush, Edward Burton, Yasimin Cabot, Nadia Toppler
Associate Professor Edward D Burton
Schwertmannite [Fe8O8(OH)6SO4] has recently been found to be the dominant mineral of iron precipitate accumulations from surface environments surrounding waterways (e.g. the sides of drains and in litter layers) in acid sulfate soil landscapes in eastern Australia. In this study the yellowish-brown, orange-brown, and reddishbrown coatings on macropores (such as channels and planar pores) in 21 soil layers from 10 sites all located within severely-acidified acid sulfate soil landscapes in eastern Australia, were isolated and examined by both differential XRD and SEM-EDS to determine if schwertmannite was present. Schwertmannite was detected in these coatings in 14 of these 21 soil …
Formation And Fate Of Disordered Mackinawite (Fes) In Acid Sulfate Soil Landscapes, Edward Burton, Richard Bush, Leigh Sullivan
Formation And Fate Of Disordered Mackinawite (Fes) In Acid Sulfate Soil Landscapes, Edward Burton, Richard Bush, Leigh Sullivan
Associate Professor Edward D Burton
Coastal lowland acid sulfate soils (CLASS) impact over 8 million ha of valuable land in Australia, and over 24 million ha throughout the world. Poor water quality in CLASS landscapes is a major threat to ecosystem health, agricultural sustainability and fisheries productivity. Research into this problem over the past three decades has focussed largely on pyrite oxidation and the release of acid-sulfate leachate into nearby waterways. However, extreme concentrations of a newly identified sulfide mineral, disordered mackinawite (FeS), exist in many CLASS landscapes. Our research indicates that the formation and fate of sedimentary FeS in floodplain drains and wetlands has …
Deoxygenation And Acidification Dynamics In Acid Sulfate Soil Landscapes: Flood-Induced Oxidation Of Sulfidic Drain Materials, Diane Fyfe, Richard Bush, Edward Burton, Leigh Sullivan
Deoxygenation And Acidification Dynamics In Acid Sulfate Soil Landscapes: Flood-Induced Oxidation Of Sulfidic Drain Materials, Diane Fyfe, Richard Bush, Edward Burton, Leigh Sullivan
Associate Professor Edward D Burton
Drain sediments in acid sulfate soil landscapes often contain large amounts (1–6% dry mass) of highly reactive iron monosulfide minerals. The mobilisation and interaction of these materials with floodwaters is thought to contribute to the intense deoxygenation and acidification that is a common phenomenon in coastal lowland rivers. We examined changes to sediment and water chemistry during laboratory experiments designed to simulate flood-induced sediment re-suspension events. Our results demonstrate that iron monosulfide minerals oxidised within minutes, rapidly consuming available oxygen. Where oxygen was continuously bubbled through the suspension, the half-life of the iron monosulfide was < 15 minutes, with it completely reacting within 4 hours. The complete oxidation of iron monosulfide to sulfate is an acid liberating process. Curiously, pH remained near-neutral during iron monosulfide oxidation with extreme acidification (pH < 3.5) developing only after 4 days. The deoxygenation and acidification processes appear to occur in two distinct steps. The first step involves the rapid oxidation of iron monosulfides and formation of elemental sulfur. This is followed by acidity released during the oxidation of elemental sulfur to sulfate and the formation of characteristic ferric iron precipitates. These results clarify important linkages between water quality and the management of low lying coastal floodplain landscapes.
Elemental Sulfur Dynamics In The Contemporary Redox-Driven Cycles Of Coastal Lowland Acid Sulfate Soils, Richard Bush, Edward Burton, Leigh Sullivan, Diane Fyfe
Elemental Sulfur Dynamics In The Contemporary Redox-Driven Cycles Of Coastal Lowland Acid Sulfate Soils, Richard Bush, Edward Burton, Leigh Sullivan, Diane Fyfe
Associate Professor Edward D Burton
Elemental sulfur has an important role in the digenic transformation of precursor iron monosulfide minerals to pyrite. It and related polysulfide intermediates are known to enable the rapid formation of pyrite, including complex framboidal morphologies, and it is a key component for pyrite formation in sub-oxic environments such as sub-tidal sediments. Lesser known for elemental sulfur is its role in the contemporary sulfur-cycle of coastal lowland acid sulfate soil landscapes involving iron monosulfide formation and acidifying oxidation processes. We present new data on the occurrence and dynamics of elemental sulfur from coastal acid sulfate soil landscapes and laboratory oxidative resuspensions …
Sedimentary Iron Cycling In Waterways Associated With Acid Sulfate Soils, Edward Burton, Richard Bush, Leigh Sullivan
Sedimentary Iron Cycling In Waterways Associated With Acid Sulfate Soils, Edward Burton, Richard Bush, Leigh Sullivan
Associate Professor Edward D Burton
No abstract provided.
The Influence Of Schwertmannite On Acidification And Sulfide Formation In Acid Sulfate Soil Landscapes, S Henderson, Leigh Sullivan, Richard Bush, Edward Burton
The Influence Of Schwertmannite On Acidification And Sulfide Formation In Acid Sulfate Soil Landscapes, S Henderson, Leigh Sullivan, Richard Bush, Edward Burton
Associate Professor Edward D Burton
In coastal lowland acid sulfate soil (CLASS) landscapes, the iron hydroxy-sulfate mineral schwertmannite (Fe8 O8(OH)5.5(SO4)1.25) forms as pedofeatures such as macropore coatings and as ground surface layers. A series of experiments were conducted to examine the geochemical behavior of these pedofeatures under aerobic and anaerobic conditions. Samples of schwertmannite-rich pedofeatures were suspended in water over 10 days to examine their acidification behaviour. An anaerobic incubation was undertaken over 203 days to examine the influence of these pedofeatures on water quality and the reduction of sulfate and formation of sulfide. The results clearly show that the schwertmannite-rich pedofeatures, when introduced to …
Elemental Sulfur Dynamics In Coastal Lowland Acid Sulfate Soil Landscapes, Richard Bush, Edward Burton, Diane Fyfe
Elemental Sulfur Dynamics In Coastal Lowland Acid Sulfate Soil Landscapes, Richard Bush, Edward Burton, Diane Fyfe
Associate Professor Edward D Burton
No abstract provided.
Schwertmannite In Acid Sulfate Subsoils And Associated Groundwater Geochemistry, Leigh Sullivan, Nadia Toppler, Yasmin Cabot, Richard Bush, Edward Burton
Schwertmannite In Acid Sulfate Subsoils And Associated Groundwater Geochemistry, Leigh Sullivan, Nadia Toppler, Yasmin Cabot, Richard Bush, Edward Burton
Associate Professor Edward D Burton
No abstract provided.
Geochemical Dynamics Of Sedimentary Iron In Waterways From Acid-Sulfate Soil Landscapes, Edward Burton, Richard Bush, Leigh Sullivan
Geochemical Dynamics Of Sedimentary Iron In Waterways From Acid-Sulfate Soil Landscapes, Edward Burton, Richard Bush, Leigh Sullivan
Associate Professor Edward D Burton
The geochemical cycling of iron (Fe) is of great significance as a regulator of pH and contaminant mobility in soil, sediment and water. Pyrite (FeS2(s) oxidation is a particularly important aspect of Fe behaviour associated with ore/coal mining and coastal lowlands. The geochemical dynamics of Fe in the context of Acid Mine Drainage (AMD) environments has been studied intensively. In contrast, Fe geochemistry in waterways associated with coastal lowland Acid-Sulfate Soils (ASS) has received comparatively little research. Therefore, the objective of this study was to determine the solubility, mineralogy and geochemical dynamics of sedimentary Fe in acid-sulfate waterways associated with …
Fractionation And Extractability Of Sulfur, Iron And Trace Elements In Sulfidic Wetland Soils, Edward Burton, Richard Bush, Leigh Sullivan
Fractionation And Extractability Of Sulfur, Iron And Trace Elements In Sulfidic Wetland Soils, Edward Burton, Richard Bush, Leigh Sullivan
Associate Professor Edward D Burton
Pyrite and other reactive iron-sulfide minerals are important to trace element behavior in many wetlands. These minerals provide sinks for potentially toxic trace elements that are introduced from anthropogenic and natural sources. The bioavailability and potential mobility of trace elements in wetland soils is therefore largely determined by the geochemical cycling of key Fe and S fractions. We examined Fe and S fractionation, and the related extractability of selected trace elements (As, Cd, Cr, Cu, Ni, Pb and Zn) in wetland soils adjacent to a former municipal landfill in eastern Australia. The soil profiles were strongly reducing (Eh < -120 mV) and contained moderately high concentrations of pore-water sulfide (200 – 600 umol/L) and acid-volatile sulfide (AVS; 9.9 – 129 umol/g). Pyrite-S concentrations increased with depth, attaining concentrations as high as 251– 669 umol/g. The Degree of Sulfidisation was generally high (> 80%), indicating …
Copper Geochemistry In An Acidic, Sandy Soil: Sorption-Desorption, Aqueous Speciation And Mobility, Edward Burton, Ian Phillips, Darryl Hawker, Dane Lamb
Copper Geochemistry In An Acidic, Sandy Soil: Sorption-Desorption, Aqueous Speciation And Mobility, Edward Burton, Ian Phillips, Darryl Hawker, Dane Lamb
Associate Professor Edward D Burton
The geochemical behavior of Cu in an acidic, sandy Podosol was examined. Sorption-desorption of Cu exhibited maximum linear distribution coefficients (Kd) at approx. pH 5. Observed depression of Kd values at pH > 5, were attributed to increased solubility of native Dissolved Organic Carbon (DOC) at higher pH and subsequent formation of poorly-sorbing Cu-DOC complexes. Speciation modelling with the MINTEQA2 code indicated that > 90 % of aqueous Cu was present as Cu-DOC complexes at pH > 5.5. The effect of Cu loading was examined with sorption isotherm analysis at pH 5 using both constant (1:2 and 1:10) and variable solid:solution ratio approaches. …
Conversion Of Naturally Occurring Schwertmannite To Hematite By Controlled Heating: Implications For Soluble Acidity And Titratable Actual Acidity, S Henderson, Leigh Sullivan, Richard Bush, Edward Burton
Conversion Of Naturally Occurring Schwertmannite To Hematite By Controlled Heating: Implications For Soluble Acidity And Titratable Actual Acidity, S Henderson, Leigh Sullivan, Richard Bush, Edward Burton
Associate Professor Edward D Burton
Naturally occurring schwertmannite (Fe8(OH)5.5(SO4)1.25), a result of acid sulfate soils (ASS) oxidation and severe acidification, has been identified as a labile source of iron, sulfate and acidity. Schwertmannite forms surface accumulations on coastal flood plains of eastern Australia. These flood plains are subject to wild fire events and fire-stick farming practices. Four samples of naturally occurring schwertmannite, from New South Wales coastal catchments, were converted to hematite by controlled heating. Complete conversion of schwertmannite to hematite (α-Fe2O3) occurred after exposure to temperatures of ≥500oC. The unheated schwertmannite and corresponding hematite samples were analysed for soluble acidity and Titratable Actual Acidity …
Investigation Of Sulfidic Sediments In A Coastal Lake Impacted By Urban Development, Bernard Powell, Leigh Sullivan, Richard Bush, Edward Burton
Investigation Of Sulfidic Sediments In A Coastal Lake Impacted By Urban Development, Bernard Powell, Leigh Sullivan, Richard Bush, Edward Burton
Associate Professor Edward D Burton
Lake Coombabah is a 2 km2, shallow, turbid estuarine system, surrounded by urbanized development situated within the Gold Coast Broadwater tidal system on the east coast of Australia; it is one of the fastest growing urban areas in the developed world 5. The region is an example of a system that demands urgent attention to the relationship between the environment and sustained development. The western shores of the Lake are heavily urbanised as is the upper catchment. Point and non-point source pollutants enter the system from urban sources (such as runoff from residential and commercial areas), acid sulfate soil disturbance, …
A Proposed Sequential Extraction Method For Metals Optimized For Acid Sulfate Soil Materials, Salirian Claff, Edward Burton, Leigh Sullivan, Richard Bush
A Proposed Sequential Extraction Method For Metals Optimized For Acid Sulfate Soil Materials, Salirian Claff, Edward Burton, Leigh Sullivan, Richard Bush
Associate Professor Edward D Burton
Acid sulfate soils are an issue of international concern. Globally they are estimated to affect 24 million ha. Little work has been done on metal behavior in acid sulfate soils especially in Australia. Metals potentially raise a number of issues in the use and remediation of acid sulfate soils, however current risk assessment and management of these soils deals with acidity production only. To adequately manage the metal contamination risk some understanding of metal mobility and availability is required. Total metal analyses give little indication of the potential mobility of the metals, and little understanding of how mobility can change …
The Influence Of Naturally Occurring Schwertmannite On Sulfur Biomineralization In Coastal Acid Sulfate Soils Landscapes, S Henderson, Leigh Sullivan, Richard Bush, Edward Burton
The Influence Of Naturally Occurring Schwertmannite On Sulfur Biomineralization In Coastal Acid Sulfate Soils Landscapes, S Henderson, Leigh Sullivan, Richard Bush, Edward Burton
Associate Professor Edward D Burton
In acid sulfate soil affected landscapes the iron oxide mineral schwertmannite (Fe8 (OH)5.5(SO4)1.25) is often abundant, forming coatings on ground surfaces and soil peds. Recent research has demonstrated that schwertmannite is a labile source of iron, sulfate and acidity, and may be the major mineral phase controlling water quality in these landscapes. We report experimental evidence that schwertmannite may also have an important role in the contemporary sulfur cycle, particularly sulfur reduction and accumulation of Monosulfidic-Black-Ooze (MBO). In-vitro anaerobic incubations were undertaken over 203 days to examine the influence of naturally occurring schwertmannite precipitates on the reduction and precipitation of …
Iron-Sulfur Biomineralisation And Arsenic Mobility In Acid-Sulfate Wetlands, Edward Burton, Scott Johnston, Richard Bush, Leigh Sullivan, Kym Watling, Annabelle Keene
Iron-Sulfur Biomineralisation And Arsenic Mobility In Acid-Sulfate Wetlands, Edward Burton, Scott Johnston, Richard Bush, Leigh Sullivan, Kym Watling, Annabelle Keene
Associate Professor Edward D Burton
Iron sulfide oxidation in drained coastal lowland soils liberates acidity, Fe and SO4, and leads to the accumulation of secondary Fe(III) minerals, such as schwertmannite (Fe8O8(OH)6SO4). Here we describe new insights on Fe-S biomineralisation and the associated mobility of As following the re-establishment of reducing conditions in reflooded acid sulfate wetlands. Our studies include controlled laboratorybased experiments on model systems as well as field-based observations on acid sulfate wetlands [1-3]. When subjected to prolonged soil waterlogging as a result of wetland re-establishment, the bacterial reduction of schwertmannite-derived Fe(III) releases abundant Fe2+ (with up to 30 mM in affected groundwater) This …