List of Titles

Mobility of arsenic and selected metals during re-flooding of iron- and organic-rich acid-sulfate soil

- Burton, Edward, Bush, Richard, Sullivan, Leigh, Johnston, Scott, Hocking, Rosalie

Authors: Burton, Edward , Bush, Richard , Sullivan, Leigh , Johnston, Scott , Hocking, Rosalie
Date: 2008
Type: Text , Journal article
Relation: Chemical Geology Vol. 253, no. 1-2 (2008), p. 64-73
Full Text: false
Reviewed:
Description: The drainage-induced oxidation of iron-sulfide minerals in acid-sulfate soils has adversely affected large areas of coastal floodplains. Re-flooding of these soils, via the re-establishment of more natural drainage regimes, is a potential remediation approach. Here we describe the mobility of Al, As, Fe, Mn, Ni and Zn during controlled re-flooding of an Fe- and organic-rich acid-sulfate soil material. Soil re-flooding caused the onset of microbially-mediated Fe(III)-reduction, which raised the pH of the initially acidic (pH 3.4) soil to pH 6.0 to 6.5, thereby immobilizing Al. The process of Fe(III)-reduction released high concentrations of FeII and was associated with significant mobilization of As. During the early stages of re-flooding, FeII mobility was controlled by dissolution of schwertmannite (Fe8O8(OH)6SO4) with an ion activity product (IAP) of 1019 Â± 2. The mobility of FeII was subsequently controlled by the precipitation of siderite (FeCO3) with an IAP spanning 10- 10 to 10- 7.5. The formation of acid-volatile sulfide (AVS), as a product of SO4-reduction, further retarded the mobility of FeII. Interactions with AVS also strongly immobilized Mn, Ni and Zn, yet had little effect on As which remained relatively mobile in the re-flooded soil. This study shows that the mobilization of As and Fe during soil re-flooding should be considered when planning remediation approaches for acid-sulfate soils. © 2008 Elsevier B.V. All rights reserved.

Ongoing soil arsenic exposure of children living in an historical gold mining area in regional Victoria, Australia: Identifying risk factors associated with uptake

- Martin, Rachael, Dowling, Kim, Pearce, Dora, Bennett, John, Stopic, Attila

Authors: Martin, Rachael , Dowling, Kim , Pearce, Dora , Bennett, John , Stopic, Attila
Date: 2013
Type: Text , Journal article
Relation: Journal of Asian Earth Sciences Vol. 77, no. (2013), p. 256-261
Full Text: false
Reviewed:
Description: Elevated levels of arsenic have been observed in some mine wastes and soils around historical gold mining areas in regional Victoria, Australia. Arsenic uptake from soil by children living in these areas has been demonstrated using toenail arsenic concentration as a biomarker, with evidence of some systemic absorption associated with periodic exposures. We conducted a follow-up study to ascertain if toenail arsenic concentrations, and risk factors for exposure, had changed over a five year period in an historical gold mining region in western regional Victoria, Australia. Residential soil samples (N= 14) and toenail clippings (N= 24) were analyzed for total arsenic using instrumental neutron activation analysis, including 19 toenail clippings samples that were obtained from the same study cohort in 2006. Toenail arsenic concentrations in 2011 (geometric mean, 0.171. μg/g; range, 0.030-0.540. μg/g) were significantly lower than those in 2006 (geometric mean, 0.464. μg/g; range, 0.150-2.10. μg/g; p<. 0.001). However, toenail arsenic concentrations were again correlated with soil arsenic levels (Spearman's rho= 0.630; p= 0.001). Spending time outdoors more often and for longer periods correlates with increased arsenic uptake (p< 0.05). Mining-influenced residential soils represent a long-term continuing source for potential arsenic exposure for children living in this historical mining region. © 2013.
Description: C1

A simple and inexpensive chromium-reducible sulfur method for acid-sulfate soils

- Burton, Edward, Sullivan, Leigh, Bush, Richard, Johnston, Scott, Keene, Annabelle

Authors: Burton, Edward , Sullivan, Leigh , Bush, Richard , Johnston, Scott , Keene, Annabelle
Date: 2008
Type: Text , Journal article
Relation: Applied Geochemistry Vol. 23, no. 9 (2008), p. 2759-2766
Full Text: false
Reviewed:
Description: A new chromium-reducible sulfur (CRS) method suitable for the quantification of reduced inorganic S (RIS) in acid-sulfate soils is presented. The new method utilises the reduction of RIS by an acidic Cr(II) solution within a sealed reaction chamber and diffusion of the produced H2S(g) into an alkaline Zn solution. It offers rapid sample processing times, without the need for large volumes of high-purity N2(g) or for specialized, expensive glassware. Examination of pyrite-talc mixtures containing up to 11.8% pyrite, revealed that the method achieves 95-98% recovery of RIS. A comparison between CRS measured by the new diffusion-based method and that measured by a standard purge-and-trap method for 25 pyritic soil samples shows a very strong (r2 = 0.996) linear relationship with a slope of 0.995. The ability of the new diffusion-based CRS method to achieve accurate and precise quantification of RIS in acid-sulfate soils is demonstrated. © 2008 Elsevier Ltd. All rights reserved.

Tectonic and economic implications of trace element, Ar-40/Ar-39 and Sm-Nd data from mafic dykes associated with orogenic gold minerals in central Victoria, Australia : reply

- Bierlein, Frank, Hughes, Martin, Dunphy, J., McKnight, Stafford

Authors: Bierlein, Frank , Hughes, Martin , Dunphy, J. , McKnight, Stafford
Date: 2002
Type: Text , Journal article
Relation: Lithos Vol. 63, no. 1-2 (Jul 2002), p. 119-123
Full Text: false
Reviewed:

Medical Geology in Asia: Toxic materials in the environment and human diseases

- Jean, Jiinshuh, Guo, Howran, Dowling, Kim, Akhtar, Rais

Authors: Jean, Jiinshuh , Guo, Howran , Dowling, Kim , Akhtar, Rais
Date: 2013
Type: Text , Journal article
Relation: Journal of Asian Earth Sciences Vol. 77, no. (2013), p. 255
Full Text: false
Reviewed:
Description: Editorial
Description: C1

Iron(III) accumulations in inland saline waterways, Hunter Valley, Australia : Mineralogy, micromorphology and pore-water geochemistry

- Isaacson, Lloyd, Burton, Edward, Bush, Richard, Mitchell, David, Johnston, Scott, Macdonald, Bennett, Sullivan, Leigh, White, Ian

Authors: Isaacson, Lloyd , Burton, Edward , Bush, Richard , Mitchell, David , Johnston, Scott , Macdonald, Bennett , Sullivan, Leigh , White, Ian
Date: 2009
Type: Text , Journal article
Relation: Applied Geochemistry Vol. 24, no. 10 (2009), p. 1825-1834
Full Text: false
Reviewed:
Description: Discharge of Fe(II)-rich groundwaters into surface-waters results in the accumulation of Fe(III)-minerals in salinized sand-bed waterways of the Hunter Valley, Australia. The objective of this study was to characterise the mineralogy, micromorphology and pore-water geochemistry of these Fe(III) accumulations. Pore-waters had a circumneutral pH (6.2-7.2), were sub-oxic to oxic (Eh 59-453 mV), and had dissolved Fe(II) concentrations up to 81.6 mg L-1. X-ray diffraction (XRD) on natural and acid-ammonium-oxalate (AAO) extracted samples indicated a dominance of 2-line ferrihydrite in most samples, with lesser amounts of goethite, lepidocrocite, quartz, and alumino-silicate clays. The majority of Fe in the samples was bound in the AAO extractable fraction (FeOx) relative to the Na-dithionite extractable fraction (FeDi), with generally high FeOx:FeDi ratios (0.52-0.92). The presence of nano-crystalline 2-line ferrihydrite (Fe5HO3Â·4H2O) with lesser amounts of goethite (Î±-FeOOH) was confirmed by scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX), and transmission electron microscopy (TEM) coupled with selected area electron diffraction (SAED). In addition, it was found that lepidocrocite (Î³-FeOOH), which occurred as nanoparticles as little as âˆ¼5 lattice spacings thick perpendicular to the (0 2 0) lattice plane, was also present in the studied Fe(III) deposits. Overall, the results highlight the complex variability in the crystallinity and particle-size of Fe(III)-minerals which form via oxidation of Fe(II)-rich groundwaters in sand-bed streams. This variability may be attributed to: (1) divergent precipitation conditions influencing the Fe(II) oxidation rate and the associated supply and hydrolysis of the Fe(III) ion, (2) the effect of interfering compounds, and (3) the influence of bacteria, especially Leptothrix ochracea. © 2009 Elsevier Ltd. All rights reserved.

Metal partitioning dynamics during the oxidation and acidification of sulfidic soil

- Claff, Salirian, Burton, Edward, Sullivan, Leigh, Bush, Richard

Authors: Claff, Salirian , Burton, Edward , Sullivan, Leigh , Bush, Richard
Date: 2011
Type: Text , Journal article
Relation: Chemical Geology Vol. 286, no. 3-4 (2011), p. 146-157
Full Text: false
Reviewed:
Description: The oxidation and acidification of sulfidic soil can lead to changes to metal mobility that can have far-reaching environmental consequences. In this study, we examined changes in the partitioning and mobility of Fe, Cr, Cu, Mn, Ni and Zn in four sulfidic soils, due to sulphide oxidation driven acidification, over a 90. day period. These changes were examined using a novel six-step sequential extraction procedure specifically developed for acid sulphate soil materials. The results demonstrate two distinct steps for the mobilisation of metals in disturbed acid sulphate soil materials, associated with (i) oxidation and (ii) acidification. Initially, oxidation causes metals to be redistributed from the "pyritic" and "organic" fractions to the "acid-soluble" fraction. Subsequent acidification, due to exceedance of the acid neutralising capacity of the soil, drives the release of metals to the "labile" fraction. This study demonstrates the importance of these metal pools in understanding the short-term processes which mobilise metals in sulfidic soils. © 2011 Elsevier B.V.

Abundance and fractionation of Al, Fe and trace metals following tidal inundation of a tropical acid sulfate soil

- Johnston, Scott, Burton, Edward, Bush, Richard, Keene, Annabelle, Sullivan, Leigh, Smith, Douglas, McElnea, Angus, Ahern, Col, Powell, Bernard

Authors: Johnston, Scott , Burton, Edward , Bush, Richard , Keene, Annabelle , Sullivan, Leigh , Smith, Douglas , McElnea, Angus , Ahern, Col , Powell, Bernard
Date: 2010
Type: Text , Journal article
Relation: Applied Geochemistry Vol. 25, no. 3 (2010), p. 323-335
Full Text: false
Reviewed:
Description: Tidal inundation was restored to a severely degraded tropical acid sulfate soil landscape and subsequent changes in the abundance and fractionation of Al, Fe and selected trace metals were investigated. After 5 a of regular tidal inundation there were large decreases in water-soluble and exchangeable Al fractions within former sulfuric horizons. This was strongly associated with decreased soil acidity and increases in pH, suggesting pH-dependent immobilisation of Al via precipitation as poorly soluble phases. The water-soluble fractions of Fe, Zn, Ni and Mn also decreased. However, there was substantial enrichment (2-5Ã—) of the reactive Fe fraction (FeR; 1 M HCl extractable) near the soil surface, plus a closely corresponding enrichment of 1 M HCl extractable Cr, Zn, Ni and Mn. Surficial accumulations of Fe(III) minerals in the inter-tidal zone were poorly crystalline (up to 38% FeR) and comprised mainly of schwertmannite (Fe8O8(OH)6SO4) with minor quantities of goethite (Î±-FeOOH) and lepidocrocite (Î³-FeOOH). These Fe (III) mineral accumulations provide an effective substrate for the adsorption/co-precipitation and accumulation of trace metals. Arsenic displayed contrary behaviour to trace metals with peak concentrations (âˆ¼60 Î¼g g-1) near the redox minima. Changes in the abundance and fractionation of the various metals can be primarily explained by the shift in the geochemical regime from oxic-acidic to reducing-circumneutral conditions, combined with the enrichment of reactive Fe near the soil surface. Whilst increasing sequestration of trace metals via sulfidisation is likely to occur over the long-term, the current abundance of reactive Fe near the sediment-water interface favours a dynamic environment with respect to metals in the tidally inundated areas. © 2009 Elsevier Ltd. All rights reserved.

Tectonic and economic implications of trace element, Ar-40/Ar-39 and Sm-Nd data from mafic dykes associated with orogenic gold mineralisation in central Victoria, Australia

- Bierlein, Frank, Hughes, Martin, Dunphy, J., McKnight, Stafford, Reynolds, P., Waldron, H.

Authors: Bierlein, Frank , Hughes, Martin , Dunphy, J. , McKnight, Stafford , Reynolds, P. , Waldron, H.
Date: 2001
Type: Text , Journal article
Relation: Lithos Vol. 58, no. 1-2 (Aug 2001), p. 1-31
Full Text: false
Reviewed:
Description: Mafic to intermediate dykes are spatially and temporally closely associated with major post-tectonic granitic complexes in the western Lachlan Orogen of SE Australia. These dykes, which range petrographically from basaltic to andesitic, are concentrated within several, north- to northwest-trending zones and were emplaced during two broad intervals of extensive magmatic activity during the Silurian–Devonian period. Geochemical and Sm–Nd isotopic characteristics of these mafic intrusives are consistent with their formation in a complex subduction-related tectonic setting. Interaction between mantle-wedge material, sinking oceanic crust and input from the overlying continental crust resulted in the petrological and geochemical variations displayed by these and more felsic dykes throughout the study region. Field evidence and 40Ar/39Ar data show that in the eastern part of the Stawell Zone and in the northwest portion of the Bendigo Zone, mafic dyke were intruded between 410 and 400 Ma (Late Silurian/Early Devonian). Further emplacement in the Bendigo Zone and the eastern part of the Melbourne Zone took place at between 375 and 365 Ma (Middle to Late Devonian). Episodic mantle-derived magmatism was possibly related to step-wise rollback, slab detachment or changes in the angle and rate of westward subduction in response to periodically occurring accretionary pulses. A close spatial and temporal relationship also exists between the dykes and orogenic gold mineralisation in the central Victorian gold province. Mafic to intermediate dykes both crosscut, and are host to, mineralisation in a number of goldfields. Although there is little evidence for a direct genetic association, the two processes are linked by the common utilisation of translithospheric structures, which facilitated the rapid ascent into shallow crustal levels of both mantle-derived magma and crustal-scale ore-forming fluid systems. Previous studies have suggested that transfer of heat into the crust via ascending mafic mantle magmas can provide a thermal engine which triggers and sustains extensive crustal melting, thus explaining the commonly observed close association of mafic to intermediate and felsic intrusive suites. This study supports the viability of this mechanism and in addition, indicates that a causal link exists between the formation of mantle magmas in collisional zones and the generation of orogenic gold deposits.
Description: C1

Oppositional defiant disorder: Prevalence based on parent and teacher ratings of Malaysian primary school children

- Gomez, Rapson, Hafetz, Nina, Gomez, Rashika

Authors: Gomez, Rapson , Hafetz, Nina , Gomez, Rashika
Date: 2013
Type: Text , Journal article
Relation: Asian Journal of Psychiatry Vol. 6, no. 4 (2013), p. 299-302
Full Text: false
Reviewed:
Description: Background: This study examined the prevalence rate of Oppositional Defiant Disorder (ODD) in Malaysian primary school children. Methods: In all 934 Malaysian parents and teachers completed ratings of their children using a scale comprising DSM-IV-TR ODD symptoms. Results: Results showed rates of 3.10%, 3.85%, 7.49% and 0.64% for parent, teacher, parent or teacher ("or-rule"), and parent and teacher ("and-rule") ratings, respectively. When the functional impairment criterion was not considered, the rate reported by parents was higher at 13.28%. Discussion: The theoretical, diagnostic and cultural implications of the findings are discussed. © 2013 Elsevier B.V.
Description: C1

Iron geochemical zonation in a tidally inundated acid sulfate soil wetland

- Johnston, Scott, Keene, Annabelle, Bush, Richard, Burton, Edward, Sullivan, Leigh, Isaacson, Lloyd, McElnea, Angus, Ahern, Col, Smith, C. Douglas, Powell, Bernard

Authors: Johnston, Scott , Keene, Annabelle , Bush, Richard , Burton, Edward , Sullivan, Leigh , Isaacson, Lloyd , McElnea, Angus , Ahern, Col , Smith, C. Douglas , Powell, Bernard
Date: 2011
Type: Text , Journal article
Relation: Chemical Geology Vol. 280, no. 3-4 (2011), p. 257-270
Full Text: false
Reviewed:
Description: Tidal inundation is a new technique for remediating coastal acid sulfate soils (CASS). Here, we examine the effects of this technique on the geochemical zonation and cycling of Fe across a tidally inundated CASS toposequence, by investigating toposequence hydrology, in situ porewater geochemistry, solid-phase Fe fractions and Fe mineralogy. Interactions between topography and tides exerted a fundamental hydrological control on the geochemical zonation, redistribution and subsequent mineralogical transformations of Fe within the landscape. Reductive dissolution of Fe(III) minerals, including jarosite (KFe3(SO4)2(OH)6), resulted in elevated concentrations of porewater Fe2+ (>30mmol L-1) in former sulfuric horizons in the upper-intertidal zone. Tidal forcing generated oscillating hydraulic gradients, driving upward advection of this Fe2+-enriched porewater along the intertidal slope. Subsequent oxidation of Fe2+ led to substantial accumulation of reactive Fe(III) fractions (up to 8000Î¼mol g-1) in redox-interfacial, tidal zone sediments. These Fe(III)-precipitates were poorly crystalline and displayed a distinct mineralisation sequence related to tidal zonation. Schwertmannite (Fe8O8(OH)6SO4) was the dominant Fe mineral phase in the upper-intertidal zone at mainly low pH (3-4). This was followed by increasing lepidocrocite (Î³-FeOOH) and goethite (Î±-FeOOH) at circumneutral pH within lower-intertidal and subtidal zones. Relationships were evident between Fe fractions and topography. There was increasing precipitation of Fe-sulfide minerals and non-sulfidic solid-phase Fe(II) in the lower intertidal and subtidal zones. Precipitation of Fe-sulfide minerals was spatially co-incident with decreases in porewater Fe2+. A conceptual model is presented to explain the observed landscape-scale patterns of Fe mineralisation and hydro-geochemical zonation. This study provides valuable insights into the hydro-geochemical processes caused by saline tidal inundation of low lying CASS landscapes, regardless of whether inundation is an intentional strategy or due to sea-level rise. © 2010 Elsevier B.V.

Seawater inundation of coastal floodplain sediments : Short-term changes in surface water and sediment geochemistry

- Wong, Vanessa, Johnston, Scott, Burton, Edward, Hirst, Phillip, Sullivan, Leigh, Bush, Richard, Blackford, Mark

Authors: Wong, Vanessa , Johnston, Scott , Burton, Edward , Hirst, Phillip , Sullivan, Leigh , Bush, Richard , Blackford, Mark
Date: 2015
Type: Text , Journal article
Relation: Chemical Geology Vol. 398, no. (2015), p. 32-45
Full Text: false
Reviewed:
Description: 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 14days 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, Ni and Zn) were observed in most sites inundated with 50% or 100% seawater. This was generally attributed to competitive exchange and desorption of trace metals from sediments due to the higher ionic strength of the seawater solutions and upward diffusive flux of metals from the sediments to surface waters. At one backswamp site, reductive processes had established by day 7, which also resulted in elevated Fe2+ concentrations in the overlying surface waters. Transmission electron microscopy (TEM) identified the presence of poorly crystalline ferrihydrite and schwertmannite, and goethite and jarosite. These meta-stable Fe(III) minerals can act as a source of metals for desorption and can also be readily reduced and act as a source of Fe2+ to surface waters. Importantly, inundation with either 50% or 100% seawater resulted in a similar magnitude of acidity and trace metal mobilisation. The data suggest that an inundation event of ~0.2m depth with either 50% or 100% seawater could cause a pulse mobilisation of up to 64.8 and 9.1kgha-1 of Fe and Al, respectively - quantities of similar magnitude to previous estimates of annual drainage fluxes from similar backswamps. This study suggests that the short term inundation of coastal floodplain sediments by either brackish water or seawater will result in rapid declines in surface water quality as a result of increased liberation of acidity and trace metals. © 2015 .

Enrichment and heterogeneity of trace elements at the redox-interface of Fe-rich intertidal sediments

- Keene, Annabelle, Johnston, Scott, Bush, Richard, Burton, Edward, Sullivan, Leigh, Dundon, Matthew, McElnea, Angus, Smith, C. Douglas, Ahern, Col, Powell, Bernard

Authors: Keene, Annabelle , Johnston, Scott , Bush, Richard , Burton, Edward , Sullivan, Leigh , Dundon, Matthew , McElnea, Angus , Smith, C. Douglas , Ahern, Col , Powell, Bernard
Date: 2014
Type: Text , Journal article
Relation: Chemical Geology Vol. 383, no. (2014), p. 1-12
Full Text: false
Reviewed:
Description: 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 depth) former sulfuric horizon sediments of a coastal acid sulfate soil (CASS). Reactive Fe was enriched at the redox interface by up to 16 times (197. g. Fe/kg) that of the former sulfuric horizon. The proportion of total trace elements associated with reactive phases was high in interfacial sediments, representing over 90% of B and U and 50% of Pb, Cu, Zn, V and Ba extractable by dilute HCl. The interfacial sediments were particularly enriched in reactive Cr, Cu, Ni, Zn, B, Mo and U, with reactive B, Mo and U concentrations between 5 and 10 times greater than in the former sulfuric horizon. Surface enrichment of trace elements is strongly co-associated with Fe(III) mineralisation, likely via sorption and co-precipitation processes. Enrichment is highly spatially heterogeneous and is strongly influenced by elevation and tidal zonation at a landscape-scale and by sediment micro-topography and preferential advective transport via surface connected macropores at the pedon-scale. The results from this study provide new insights to the processes influencing trace element enrichment in Fe-rich redox-interfacial sediments across a remediating acidic tidal wetland. © 2014 Elsevier B.V.

Schwertmannite transformation to goethite via the Fe(II) pathway : Reaction rates and implications for iron-sulfide formation

- Burton, Edward, Bush, Richard, Sullivan, Leigh, Mitchell, David

Authors: Burton, Edward , Bush, Richard , Sullivan, Leigh , Mitchell, David
Date: 2008
Type: Text , Journal article
Relation: Geochimica et Cosmochimica Acta Vol. 72, no. 18 (2008), p. 4551-4564
Full Text: false
Reviewed:
Description: Schwertmannite (Fe8O8(OH)6SO4) is a common Fe(III)-oxyhydroxysulfate mineral in acid-sulfate systems, where its formation and fate strongly influence water quality. The present study examines transformation of schwertmannite to goethite (FeOOH), as catalyzed by interactions with Fe(II) in anoxic aquatic environments. This study also evaluates the role of the Fe(II) pathway in influencing the formation of iron-sulfide minerals in such environments. At pH > 5, the rates of Fe(II)-catalyzed schwertmannite transformation were several orders of magnitude faster than transformation in the absence of Fe(II). Complete transformation of schwertmannite occurred within only 3-5 h at pH > 6 and Fe(II)(aq) â‰¥ 5 mmol L-1. Model calculations indicate that the Fe(II)-catalyzed transformation of schwertmannite to goethite greatly decreases the reactivity of the Fe(III) pool, thereby favoring SO4-reduction and facilitating the formation of iron-sulfide minerals (particularly mackinawite, tetragonal FeS). Examination of in situ sediment geochemistry in an acid-sulfate system revealed that the rapid Fe(II)-catalyzed transformation was consistent with an abrupt shift from an acidic Fe(III)-reducing regime with abundant schwertmannite near the sediment surface, to a near-neutral mackinawite-forming regime where goethite was dominant. This study demonstrates that the Fe(II) pathway exerts a major influence on schwertmannite transformation and iron-sulfide formation in anoxic acid-sulfate systems. These findings have important implications for understanding acidity dynamics and trace element mobility in such systems. © 2008 Elsevier Ltd. All rights reserved.

Volcanism in Aboriginal Australian oral traditions : ethnographic evidence from the newer volcanics province

- Wilkie, Benjamin, Cahir, David (Fred), Clark, Ian

Authors: Wilkie, Benjamin , Cahir, David (Fred) , Clark, Ian
Date: 2020
Type: Text , Journal article
Relation: Journal of Volcanology and Geothermal Research Vol. 403, no. (2020), p. 1-11
Full Text: false
Reviewed:
Description: This article collects and presents nineteenth-century ethnographic evidence from the Newer Volcanics Province of Australia and explores how volcanism was recorded and understood in Aboriginal oral traditions. It investigates whether Aboriginal Australian oral traditions can be understood as persistent eyewitness accounts of volcanic eruptions in the Newer Volcanics Province, how andwhat kind of geological and volcanological knowledge was embedded within Aboriginal Australian oral traditions, and considers what value the ethnographic evidence has for understanding both the socio-cultural and geological histories of the Newer Volcanics Province.

Jarosite quantification in soils : An enhanced sequential extraction procedure

- Vithana, Chamindra, Sullivan, Leigh, Bush, Richard, Burton, Edward

Authors: Vithana, Chamindra , Sullivan, Leigh , Bush, Richard , Burton, Edward
Date: 2014
Type: Text , Journal article
Relation: Applied Geochemistry Vol. 51, no. (2014), p. 130-138
Full Text: false
Reviewed:
Description: A two-step sequential extraction procedure established for the quantification of acidity producing ferric and ferrous sulfate minerals such as melanterite and jarosite in acid mine wastes was evaluated for quantification of jarosite spiked in soils. The procedure involves in sequence anoxic water extraction, roasting the solid residue after anoxic water extraction at 550. °C for 1. h, and 4. M HCl extraction of the roasted solid. Soil and quartz samples were spiked with known amounts of synthetic and natural jarosite and their recovery was measured using the suggested two-step sequential extraction procedure. The recoveries of synthetic and natural jarosite were calculated on the basis of the S contents of the initially spiked jarosite in soil and quartz samples. Less than 50% of the spiked jarosite was recovered. The missing S is partially attributable to the retention of jarosite by the Teflon filter membrane used during the filtration of the anoxic water extract. Further investigations also demonstrated a lower 4. M HCl-S extractability from jarosite samples roasted at 550. °C than those roasted at 450. °C. S recovery from jarosite-spiked quartz samples increased to 45-70% by replacing the Teflon filter membrane with the Cellulose Acetate filter membrane and including this filter paper in the second step roasting. This modified method is a step forward in the development of methods to accurately and reliably quantify jarosite in soil materials. © 2014 Elsevier Ltd.

Quantifying alkalinity generating processes in a tidally remediating acidic wetland

- Johnston, Scott, Keene, Annabelle, Burton, Edward, Bush, Richard, Sullivan, Leigh

Authors: Johnston, Scott , Keene, Annabelle , Burton, Edward , Bush, Richard , Sullivan, Leigh
Date: 2012
Type: Text , Journal article
Relation: Chemical Geology Vol. 304-305, no. (2012), p. 106-116
Full Text: false
Reviewed:
Description: 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 6years of LATE. Quantified inputs include: marine derived HCO 3 - 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 (Î±=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 SO 4 2- 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 H 2S. 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 sufficient regenerative capacity in the adjacent estuarine/marine tidal HCO 3 - pool. © 2012 Elsevier B.V.

Near-infrared effectiveness on degraded core in tropical climates

- Jansen, Nicholas, Cooke, David, Harris, Anthony, McKnight, Stafford

Authors: Jansen, Nicholas , Cooke, David , Harris, Anthony , McKnight, Stafford
Date: 2017
Type: Text , Journal article
Relation: Economic Geology Vol. 112, no. 4 (2017), p. 1011-1019
Full Text: false
Reviewed:
Description: In tropical climates, postdrilling oxidation of sulfide-rich core can severely degrade drill core, producing lowtemperature iron oxyhydroxides, sulfates, and clays. Variable growth of these secondary minerals in exposed drill core, combined with the hydration and degradation of primary hydrothermal minerals, may lead to the production of spurious results in near-infrared (NIR) spectroscopic studies. However, the NIR technique can remain an effective tool in assessing hydrothermal alteration, even in extremely degraded core. We have assessed the usefulness of the NIR technique on degraded core at the Ladolam gold deposit, Papua New Guinea. Here, we seek to determine whether the primary alteration mineralogy had been significantly transformed by postdrilling oxidation over several years of weathering. In doing so, the study tested whether NIR analysis can be an effective tool in the discrimination of primary hydrothermal minerals in degraded core. Our study was made possible using semiquantitative X-ray diffraction (QXRD) analyses of a drill hole in 2004, where samples were collected at 50-m intervals. We subsequently repeated NIR and QXRD analyses on the same drill core in 2012. After nine years of storage, the drill core had degraded considerably, with the growth of jarosite and other sulfates. Despite this, XRD results from 2004 and 2012 show no major differences in the primary alteration mineralogy. Closely spaced NIR analyses were conducted at 1-m intervals to increase the chance of obtaining a spectrum of the primary mineralogy and to exclude secondary oxidation minerals. The drill core, where possible, was broken immediately prior to analysis to obtain a fresh surface. On average, over a 10-m interval, approximately 25% of the NIR spectra did not contain secondary minerals and relict primary alteration minerals could be detected. The remaining spectra were affected by the occurrence of secondary jarosite, gypsum, and/or residual water, but in most cases, the primary alteration mineralogy could be determined. We conclude that NIR analyses remain an effective tool in the construction of geological deposit models when logging degraded historic core, even for sulfide-rich core that has degraded in tropical environments. © 2017 Society of Economic Geologists, Inc.

Showing items 1 - 20 of 29