Physical Sciences and Mathematics Commons^™

Iron Behavior In A Northern Estuary: Large Pools Of Non-Sulfidized Fe(Ii) Associated With Organic Matter, Changxun Yu, Joonas J. Virtasalo, Torbjörn Karlsson, Pasi Peltola, Peter Österholm, Edward D. Burton, Laura Arppe, Johan K. Hogmalm, Antti E K Ojala, Mats E. Aström

Associate Professor Edward D Burton

The estuaries of the Northern Baltic Sea (Gulf of Bothnia) receive an abundance of diagenetically reactive catchment-derived Fe, which is to a large degree complexed with organic matter or present as Fe (hydr-)oxides. However, our understanding of sedimentary Fe diagenesis in these estuaries is limited. To address this limitation, the present study examines Fe geochemistry in a 3.5-m-thick estuarine benthic mud layer and three samples of suspended particulate matter of a catchment on the eastern Gulf of Bothnia. The age–depth model of the mud, constructed on the basis of sedimentary features as well as ¹³⁷Cs and aquatic plant ^{14 …}

Arsenic Solid-Phase Speciation In An Alluvial Aquifer System Adjacent To The Himalayan Forehills, Nepal, Scott Johnston, Jasmine Diwakar, Edward Burton

Associate Professor Edward D Burton

Alluvial aquifers contaminated by geogenic arsenic often lack direct solid-phase speciation data, hindering efforts to understand landscape-scale spatial heterogeneity and controls on As mobility. Here, we examine solid-phase As and Fe speciation of alluvial aquifer, river and hyporheic-seep sediments along a topographic gradient at the Himalayan foothills/upper-Ganges floodplain margin. We employ a combination of X-ray absorption spectroscopy, selective extracts, electron microscopy and X-ray fluorescence. Source-river sediments were found to contain a mixture of solid-phase As(V) and As(III) species, while vertically heterogeneous bore-hole sediments also contained a solid-phase As-sulfide species. In general, the abundance of reduced As species [As(III) + As-sulfide] …

Sulfur, Iron And Carbon Cycling Following Hydrological Restoration Of Acidic Freshwater Wetlands, Scott Johnston, Edward Burton, Thor Aaso, Gerard Tuckerman

Associate Professor Edward D Burton

Freshwater re-flooding is a relatively novel approach to remediate drained acid sulfate soil (ASS) wetlands. This study documents the geochemical consequences of restoring freshwater re-flooding for contemporary reduced inorganic sulfur (RIS) and iron species in two coastal floodplain ASS wetlands. Re-flooding has established predominantly reducing/suboxic conditions and encouraged organic carbon accumulation in surface sediments (~ 20–30%). The pH of former sulfuric horizons has increased by ~ 2–3 units, partly in response to alkalinity generation from anaerobic metabolism of organic carbon coupled with Fe(III) and SO42 − reduction. Despite considerable sulfidisation, reactive Fe (FeR; sum of 1 M HCl and citrate–dithionite …

Arsenic Mobility During Flooding Of Contaminated Soil: The Effect Of Microbial Sulfate Reduction, Edward Burton, Scott Johnston, Benjamin Kocar

Associate Professor Edward D Burton

In floodplain soils, As may be released during flooding-induced soil anoxia, with the degree of mobilization being affected by microbial redox processes such as the reduction of As(V), Fe(III), and SO42–. Microbial SO42– reduction may affect both Fe and As cycling, but the processes involved and their ultimate consequences on As mobility are not well understood. Here, we examine the effect of microbial SO42 reduction on solution dynamics and solid-phase speciation of As during flooding of an As-contaminated soil. In the absence of significant levels of microbial SO42– reduction, flooding caused increased Fe(II) and As(III) concentrations over a 10 week …

Seawater Inundation Of Coastal Floodplain Sediments: Short-Term Changes In Surface Water And Sediment Geochemistry, Vanessa Wong, Scott Johnston, Edward Burton, Phillip Hirst, Leigh Sullivan, Richard Bush, Mark Blackford

Associate Professor Edward D Burton

Coastal floodplains are highly vulnerable to seawater inundation as a result of storm surge and sea-level rise due to their low elevation and proximity to the coastline. Intact soil cores from a levee, acid-sulfate soil scald and four backswamp sites on a coastal floodplain in eastern Australia were inundated with artificial seawater treatments (0%, 50% and 100%) for 14 days to examine the short term consequences for surface water and floodplain sediment geochemistry. All sites displayed an initial decrease in surface water pH following inundation with 50% and 100% seawater. In addition, higher concentrations of trace metals (Al, Fe, Mn, …

Arsenic Mobilization In An Alluvial Aquifer Of The Terai Region, Nepal, Jasmine Diwakar, Scott Johnston, Edward Burton, Suresh Das Shrestha

Associate Professor Edward D Burton

Study Region

A shallow (<50 m) alluvial aquifer in the Terai region of Nepal.

Study Focus

We examine the hydrogeochemical characteristics of a shallow alluvial aquifer system in the Terai region (Nawalparasi district) to identify possible mechanisms and controls on geogenic As mobilization in groundwater. Groundwater and river water samples from a topo-gradient flow-path and floodplain of a minor river draining the Siwalik forehills were analyzed for physico-chemical parameters.

New Hydrological Insights for the Region

The aquifer is characterized by Ca-HCO₃ type water and is multi-contaminated, with the WHO guideline values exceeded for As, Mn and F in 80%, 70% and 40% of cases respectively. The middle portion …

A Revised Method For Determining Existing Acidity In Re-Flooded Acid Sulfate Soils, Scott Johnston, Edward Burton, Roslyn Hagan, Thor Aaso, Gerard Tuckerman

Associate Professor Edward D Burton

Titratable actual acidity (TAA) is a technique commonly used to estimate the existing pool of exchangeable H⁺ in acid sulfate soils (ASS). A widely adopted version of the TAA method involves titrating a 1M KCl suspension of oven-dry soil (1:40) with NaOH to a known pH endpoint. However, when ASS are subject to long term re-flooding during wetland remediation, former sulfuric horizons can develop substantial quantities of porewater Fe²⁺, non-sulfidic solid-phase Fe(II) and a variety of reduced inorganic sulfur (RIS) species (e.g. pyrite, mackinawite, greigite and elemental sulfur). For these sediments, an oven-drying approach may induce oxidation …

Enrichment And Heterogeneity Of Trace Elements At The Redox-Interface Of Fe-Rich Intertidal Sediments, Annabelle Keene, Scott Johnston, Richard Bush, Edward Burton, Leigh Sullivan, Matthew Dundoon, Angus Mcelnea, C Smith, Col Ahern, Bernard Powell

Associate Professor Edward D Burton

Redox-interfacial sediments can undergo radical geochemical changes with oscillating tides. In this study, we examine trace element enrichment and availability, at both landscape and pedon-scales, in the surface sediments of a remediating acidic tidal wetland. Fe-rich sediments at the surface-water interface (0–10 mm in depth) were collected across an elevation gradient spanning the supratidal to subtidal range. These sediments were analysed for solid phase Fe fractions and trace elements (As, Pb, Cr, Cu, Mn, Ni, Zn, V, B, Co, Mo, Ba and U) via dilute HCl-extractions and total digests. Their concentrations were compared with those of underlying (0.05–0.65 m in …

Landslide-Induced Iron Mobilisation Shapes Benthic Accumulation Of Nutrients, Trace Metals And Ree Fractionation In An Oligotrophic Alpine Stream, Scott Johnston, Andrew Rose, Edward Burton, Jenny Webster-Brown

Associate Professor Edward D Burton

Large alpine landslides that entrain substantial organic material below the water table and create suspended floodplains may have long-term consequences for the mobilisation of redox sensitive elements, such as Fe, into streamwaters. In turn, the cycling of iron in aquatic systems can influence the fate of nutrients, alter primary productivity, enhance accumulation of trace metals and induce fractionation of rare earth elements (REE). In this study we examine a reach of a pristine oligotrophic alpine stream bracketing a 30 year-old landslide and explore the consequences of landslide-induced Fe mobilisation for aqueous geochemistry and the composition of benthic stream cobble biofilm. …

Acidity Fractions In Acid Sulfate Soils And Sediments: Contributions Of Schwertmannite And Jarosite, Chamindra Vithana, Leigh Sullivan, Richard Bush, Edward Burton

Associate Professor Edward D Burton

In Australia, the assessment of acidity hazard in acid sulfate soils requires the estimation of operationally defined acidity fractions such as actual acidity, potential sulfidic acidity, and retained acidity. Acid–base accounting approaches in Australia use these acidity fractions to estimate the net acidity of acid sulfate soils materials. Retained acidity is the acidity stored in the secondary Fe/Al hydroxy sulfate minerals, such as jarosite, natrojarosite, schwertmannite, and basaluminite. Retained acidity is usually measured as either net acid-soluble sulfur (S_NAS) or residual acid soluble sulfur (S_RAS). In the present study, contributions of schwertmannite and jarosite to the …

Liberation Of Acidity And Arsenic From Schwertmannite: Effect Of Fulvic Acid, Chamindra Vithana, Leigh Sullivan, Edward Burton, Richard Bush

Associate Professor Edward D Burton

Schwertmannite is one of the major components that produces acidity in acid mine drainage (AMD) and acid sulfate soils (ASS) and is also known to be an effective scavenger of Arsenic (As) in such environments. Fulvic acid (FA) is an active component of natural organic matter (NOM) and is known to interact strongly with both schwertmannite and As. Two main environmental hazards related to schwertmannite are acidity liberation and potential re-mobilization of adsorbed or co-precipitated As upon hydrolysis. This study focused on understanding the behaviour of As-substituted schwertmannite with regard to the potential of acidity liberation, the effect of FA …

Effect Of Fulvic Acid On Liberation Of Acidity And Arsenic Form Arsenic Substituted Schwertmannite, Chamindra Vithana, Leigh Sullivan, Richard Bush, Edward Burton

Associate Professor Edward D Burton

INTRODUCTION

Schwertmannite is one of the main secondary iron hydroxy sulfate minerals contributing to acidity in acid sulfate soils (ASS). While it is an important source of acidity in ASS, schwertmannite is also known to be a potential sink for trace metals such as arsenic (As) and chromium (Cr) (Fukushi et al. 2003; Regenspurg and Peiffer. 2005).Trace metal adsorption/substitution is known to stabilize schwertmannite which in turn retards its transformation to goethite which is one of the main processes of acidity generation in ASS. Fulvic Acid (FA) is a subclass of natural organic materials that are ubiquitous in aquatic environments …

Modifications To The Classification Of Acid Sulfate Soil Material, Leigh Sullivan, R Fitzpatrick, Richard Bush, Edward Burton, P Shand, Nicholas Ward

Associate Professor Edward D Burton

No abstract provided.

Reflooding The Exposed And Acidified Lower Lakes Sediments: Seawater Or River Murray Water, Leigh Sullivan, Richard Bush, Edward Burton, Nicholas Ward, L Barnett, L Mosley, R Seaman

Associate Professor Edward D Burton

No abstract provided.

Lower Lakes Laboratory Study Of Contaminant Mobilisation Under Seawater And Freshwater Inundation (Long-Term Study), Leigh Sullivan, Richard Bush, Nicholas Ward, Diane Fyfe, M Johnston, Edward Burton, Paul Cheeseman, Michelle Bush, Crystal Maher, Michael Cheetham, K Watling, Vanessa Wong, R Maher, E Weber

Associate Professor Edward D Burton

No abstract provided.

Bioremediation Of Acidic Lake-Bed Sediments Via Enhanced In-Situ Sulfate-Reduction: Lower Lakes, South Australia, Edward Burton, Leigh Sullivan, R Seaman, L Barnett, L Mosley, Nicholas Ward, Paul Cheeseman, Trent Mcintyre

Associate Professor Edward D Burton

No abstract provided.

Study Of Monosulfidic Black Ooze (Mbo) In The Geographe Bay Area, Western Australia, Nicholas Ward, Richard Bush, Leigh Sullivan, Edward Burton, Paul Cheeseman

Associate Professor Edward D Burton

No abstract provided.

Lower Lakes Sulfate Reduction Study (Interim Report), Leigh Sullivan, Edward Burton, Nicholas Ward, Richard Bush, J Coughran, Diane Fyfe, Paul Cheeseman, Trent Mcintyre

Associate Professor Edward D Burton

No abstract provided.

Lower Lakes Sulfate Reduction Study, Leigh Sullivan, Edward Burton, Nicholas Ward, Richard Bush, J Coughran, Michael Cheetham, Diane Fyfe, Paul Cheeseman, Trent Mcintyre

Associate Professor Edward D Burton

No abstract provided.

The Classification Of Acid Sulfate Soil Materials: Further Modifications, Leigh Sullivan, R Fitzpatrick, Richard Bush, Edward Burton, P Shand, Nicholas Ward

Associate Professor Edward D Burton

No abstract provided.

Acid Sulfate Soils: Their Characteristics, Risk Assessment, And Management Options, Leigh Sullivan, Richard Bush, Edward Burton

Associate Professor Edward D Burton

No abstract provided.

Sea-Level Rise Impacts On Coastal Water Quality: Interactions Between Porewater, Surfaceand Shallow Groundwater Geochemistry, Vanessa Wong, Scott Johnston, Phillip Hirst, Edward Burton, Richard Bush, Leigh Sullivan, Peter Slavich

Associate Professor Edward D Burton

No abstract provided.

The Effects Of Increasing Salinity On Exchange Processes In Coastal Lowland Acid Sulfate Soils, Vanessa Wong, Scott Johnston, Richard Bush, Leigh Sullivan, Edward Burton, Peter Slavich

Associate Professor Edward D Burton

10 coastal lowland acid sulfate soils (CLASS) from floodplains in eastern Australia were subjected to increasing seawater concentrations to determine the effects of exchange processes on metal desorption due to increasing ionic strength. Soils were subjected to one of six treatments; 0%, 10%, 20%, 50%, 80% or 100% seawater diluted in deionised water. pH decreased with increasing seawater concentration. In general, concentrations of Al, Cd, Fe2+ and Mn increased in soils sampled from levees, organic and mineral sulfuric horizons with increasing salinity. Increasing trace metal concentrations with increasing seawater concentration is attributed to both exchange processes and pH effects. The …

Seawater Causes Rapid Trace Metal Mobilisation In Coastal Lowland Acid Sulfate Soils: Implications Of Sea Level Rise For Water Quality, Vanessa Wong, Scott Johnston, Edward Burton, Richard Bush, Leigh Sullivan, Peter Slavich

Associate Professor Edward D Burton

Coastal floodplains are highly vulnerable to inundation with saline water and the likelihood of inundation will increase with sea level rise. Sediment samples from floodplains containing coastal lowland acid sulfate soils (CLASS) in eastern Australia were subjected to increasing seawater concentration to examine the probable effects of sea level rise on acidity and metal desorption. Ten soils were mixed with synthetic seawater concentrations varying from 0% to 100% at a solid:solution ratio of 1:10 for 4 h. There was a slight decrease in pH (≈0.5 units) with increasing seawater concentration following treatment, yet, calculated acidity increased significantly. In most soil …

Monosulfidic Black Ooze Accumulations In Sediments Of The Geographe Bay Area, Western Australia, Nicholas Ward, Richard Bush, Edward Burton, S Appleyard, S Wong, Leigh Sullivan, Paul Cheeseman

Associate Professor Edward D Burton

Mobilisation of sedimentary monosulfidic black ooze (MBO) may result in rapid deoxygenation and acidification of surface waters, and release of potentially toxic metals. This study examines the extent and nature of MBO accumulation in the Geographe Bay area, Western Australia. MBO accumulations were found to be widespread in benthic sediments of the Geographe Bay area with acid-volatile sulfide (AVS) contents as high as 320 μmol g−1. The MBO materials often had unusually high dissolved sulfide (S−II) concentrations in their pore-waters (up to 610 mg L−1) and elevated elemental sulfur (S0) contents (up to 51 μmol g−1). Dissolved S−II is able …

Climate Change: A Frontier For Acid Sulfate Soil Research, Richard Bush, Leigh Sullivan, Scott Johnston, Edward Burton, Vanessa Wong, Annabelle Keene

Associate Professor Edward D Burton

Sea-level is predicted to continue to rise this century, threatening the integrity of coastal floodplains throughout the world. The low-lying elevation of much of the 17 million ha of acid-sulfate soils that occur worldwide, renders these landscapes particularly vulnerable to the impacts of climate change. Acid sulfate soils landscapes are regulated by redox driven biogeochemical processes that are sensitive to watertable dynamics, tidal exchange and temperature. The increased likelihood of extreme weather events such as drought and floods and rising global temperatures are directly relevant to the redox and hydrological processes that influence acid sulfate soil behaviour and their impact …

Hydrological Controls On Acid Generation And Export In Floodplain Wetlands, Scott Johnston, Annabelle Keene, Edward Burton, Richard Bush, Leigh Sullivan

Associate Professor Edward D Burton

No abstract provided.

As, Fe And S Cycling During Reductive Biomineralisation Of Pedogenic Jarosite, Annabelle Keene, Scott Johnston, Edward Burton, Richard Bush

Associate Professor Edward D Burton

No abstract provided.

The Role Of Microbial Sulfidogenesis In Shaping Iron-Sulfur-Arsenic Interactions Within Floodplain Soils, Edward Burton, Scott Johnston, Richard Bush

Associate Professor Edward D Burton

No abstract provided.

Assessing Acid Sulfate Soil Neutralising Capacity: A New Approach, Leigh Sullivan, K Watling, Salirian Claff, Richard Bush, Edward Burton, Scott Johnston, C Ahern, A Mcelnea

Associate Professor Edward D Burton

No abstract provided.