Physical Sciences and Mathematics Commons^™

Occluded C In Rice Phytoliths: Implications To Biogeochemical Carbon Sequestration, Zimin Li, Zhaoliang Song, Jeffrey Parr, Hailong Wang

Jeffrey Parr

Aims: Carbon (C) bio-sequestration within the phytoliths of plants, a mechanism of long-term biogeochemical C sequestration, may play a major role in the global C cycle and climate change. In this study, we explored the potential of C bio-sequestration within phytoliths produced in cultivated rice (Oryza sativa), a well known silicon accumulator.

Methods: The rice phytolith extraction was undertaken with microwave digestion procedures and the determination of occluded C in phytoliths was based on dissolution methods of phytolith-Si.

Results: Chemical analysis indicates that the phytolith-occluded C (PhytOC) contents of the different organs (leaf, stem, sheath and grains) on …

Simultaneous Redox Conversion Of Chromium(Vi) And Arsenic(Iii) Under Acidic Conditions, Zhaohui Wang, Richard Bush, Leigh Sullivan, Jianshe Liu

Dr Zhaohui Wang

Arsenic and chromium are often abundant constituents of acid mine drainage (AMD) and are most harmful as arsenite (As(III)) and hexavalent (Cr(VI)). To simultaneously change their oxidation state from As(III) to As(V), and Cr(VI) to Cr(III), is a potentially effective and attractive strategy for environmental remediation. The coabundance of As(III) and Cr(VI) in natural environments indicates their negligible direct interaction. The addition of H2O2enables and greatly accelerates the simultaneous oxidation of As(III) and reduction of Cr(VI). These reactions are further enhanced at acidic pH and higher concentrations of Cr(VI). However, the presence of ligands (i.e., oxalate, citrate, pyrophosphate) greatly retards …

Municipal Solid Wastes And Water Quality Issues In Nigeria, S Isiorho, D Omole

S Isiorho

No abstract provided.

Sample Pre-Treatment And The Determination Of Some Chemical Properties Of Acid Sulfate Soil Materials, Crystal Maher, Leigh Sullivan, Nicholas Ward

Dr Nicholas J Ward

This study provides a systematic analysis of the effect of common acid sulfate soil (ASS) sample pre-treatments (namely freezing, oven drying, and grinding) on chromium-reducible sulfur (SCR) and water-soluble sulfate determinations. The results show that oven drying and hand grinding of the samples prior to analysis resulted in a decrease in SCR (i.e. up to 20% compared to those of frozen samples). This lower SCR value was partly due to the oxidation of sulfides in the oven. For oven-dried ASS materials, more intensive grinding in a ring mill increased SCR values, most likely by abrading coatings from pyrite grains. For …

The Response Of Partially Oxidised Acid Sulfate Soil Materials To Anoxia, Nicholas Ward, Leigh Sullivan, Richard Bush

Dr Nicholas J Ward

Four acid sulfate soil (ASS) materials were subjected to anoxia after varying periods of oxidation to determine the geochemical response of these types of soils to flooding. The response of the partially oxidised ASS materials to the exclusion of oxygen was variable. The rate of sulfide oxidation, acidification, and the production of soluble oxidation products such as sulfate, iron, and aluminium generally decreased markedly when subjected to anoxia. However, especially in the highly acidic ASS materials (i.e. pH 3+. Rapid sulfide re-formation occurred in the peat ASS material that had been oxidised for 63 days, with 0.47% reduced inorganic sulfur …

Sulfide Oxidation And Acidification Of Acid Sulfate Soil Materials Treated With Caco3 And Seawater-Neutralised Bauxite Refinery Residue, Nicholas Ward, Leigh Sullivan, Richard Bush

Dr Nicholas J Ward

Acid sulfate soil (ASS) materials that are subject to oxidation are often treated with neutralising agents to minimise the export of acidity that may result from pyrite oxidation. The effects of additions of both CaCO₃ and seawater-neutralised bauxite refinery residue (SNBRR) on the oxidation of sulfides and acidification were assessed for 4 ASS materials using laboratory incubation experiments. As the application of sub-optimal rates of neutralising materials can occur for a variety of reasons, the effect of application rates were also examined. Two application rates were chosen; a sub-optimal rate [approximately 20% of the theoretical neutralising requirement (NR)] and …

Assessment Of Peroxide Oxidation For Acid Sulfate Soil Analysis. 2. Acidity Determination, Nicholas Ward, Leigh Sullivan, Richard Bush, Chuxia Lin

Dr Nicholas J Ward

Total sulfidic acidity (TSA) and total potential acidity (TPA) are derived from peroxide oxidation of acid sulfate soil materials (ASS), and are measures of the sulfidic acidity and the net acidity (net acidity = sulfidic acidity + actual acidity – acid neutralising capacity), respectively. The TSA and TPA of 4 ASS materials were determined using a variety of peroxide oxidation procedures and compared with the sulfidic acidity and net acidity derived from the use of an acid–base accounting model. TSA and TPA values both varied greatly with each peroxide oxidation method used, and both measures were found to substantially underestimate …

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

Dr Nicholas J Ward

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 …

Improved Identification Of Sulfidic Soil Materials By A Modified Incubation Method, Leigh Sullivan, Nicholas Ward, Richard Bush, Edward Burton

Dr Nicholas J Ward

This study examines the acidification behaviour and rate of sulfidic-sulfur oxidation in the incubation method that is currently used in soil taxonomies to identify sulfidic materials, for some clayey textured soil materials. ‘Sulfidic’ in these taxonomies identifies that a soil material is capable of becoming extremely acidic (i.e. pH < 4) as a result of oxidation of sulfide minerals contained in that soil material. As well as examining incubation slabs of acid sulfate soil materials with the standard 10 mm thickness, the utility of thinner (i.e. 2 mm thick) incubation slabs of these soil materials for identification of sulfidic soil materials …

Soil Ph, Oxygen Availability, And The Rate Of Sulfide Oxidation In Acid Sulfate Soil Materials: Implications For Environmental Hazard Assessment, Nicholas Ward, Leigh Sullivan, Richard Bush

Dr Nicholas J Ward

The potential environmental hazard of acid sulfate soil (ASS) materials is directly related to both the net acidity and the rate that actual acidity is released from these soil materials into the environment. While current environmental hazard assessment techniques for ASS materials are able to quantify the net acidity, they do not take account of differences in the rate of sulfide oxidation (the dominant source of actual acidity) and differences in the rate of acidification. In this study the rate of sulfide oxidation during incubation was examined for 4 ASS materials. The effect of pH and oxygen availability on the …

The Process Of Sulfide Oxidation In Some Acid Sulfate Soil Materials, Nicholas Ward, Leigh Sullivan, Diane Fyfe, Richard Bush, Angus Ferguson

Dr Nicholas J Ward

The process of sulfide oxidation in acid sulfate soils (ASS) is complex, involving the formation of numerous oxidation products. In this study the sulfide oxidation process was examined in 2 ASS materials over a period of 36 days using laboratory incubation experiments. Both ASS materials experienced substantial sulfide oxidation and acidification during incubation. The oxidation of pyrite was the primary cause of acidification in these ASS materials. Although a decrease in magnetic susceptibility (χ) over the initial 4 days of incubation suggested the rapid oxidation of ferromagnetic iron monosulfide greigite (Fe₃S₄), the total acid volatile sulfur …

Assessment Of Peroxide Oxidation For Acid Sulfate Soil Analysis. 1. Reduced Inorganic Sulfur, Nicholas Ward, Leigh Sullivan, Richard Bush, Chuxia Lin

Dr Nicholas J Ward

The reduced inorganic sulfur fraction of 4 acid sulfate soil (ASS) materials was quantified using a variety of peroxide oxidation procedures. The temperature and duration of the peroxide oxidation were found to markedly affect the peroxide oxidisable sulfur determination. For 3 ASS materials with low total carbon content (i.e. <2.5% C), peroxide oxidisable sulfur underestimated the reduced inorganic sulfur fraction, with the peroxide oxidisable sulfur determinations being as low as 42% of those determined using chromium reducible sulfur technique. The precipitation of jarosite during peroxide oxidation was a major factor contributing to the underestimation of reduced inorganic sulfur in these materials. Apparent losses of sulfur of approximately 25% on average occurred during peroxide oxidation budget accounting; this also contributed towards the observed underestimation of reduced inorganic sulfur. It is most likely that these unaccounted losses are due to atmospheric losses of sulfur. In a peat ASS, one of the peroxide oxidation methods overestimated the reduced inorganic sulfur fraction and was attributed to the release of a large reserve of organic sulfur in this material by the peroxide. This study shows the peroxide oxidation methods examined here are subject to substantial interferences. Consequently these peroxide oxidation methods are unable to reliably provide accurate measurements of the reduced inorganic sulfur fraction in ASS materials

Limits Of Luminescence Dating: An Update Regarding Quartz Of The Southern Alps Of New Zealand And The Olympic Mountains, Washington, Usa, Cianna Wyshnytzky, Tammy Rittenour

Cianna E Wyshnytzky

Late Pleistocene glacial sediments from the South Fork Hoh River valley in the Olympic Mountains, Washington, USA and the Lake Hawea valley in the Southern Alps, New Zealand were dated using optically stimulated luminescence (OSL) on quartz and infrared stimulated luminescence (IRSL) on feldspar sand from 2011-2013. High sediment supply (typical of glacial environments), short transport distances, and sediment newly eroded from bedrock sources were expected to pose problems for luminescence dating in these locations. Samples were collected from a variety of depositional environments and inferred distances from the ice-front to assess how luminescence signals may vary due to these …

Photocatalytic Oxidation Of Organic Pollutants Catalyzed By An Iron Complex At Biocompatible Ph Values: Using O2 As Main Oxidant In A Fenton-Like Reaction, Xi Chen, Wanhong Ma, Jing Li, Zhaohui Wang, Chungcheng Chen, Hongwei Ji, Jincai Zhao

Dr Zhaohui Wang

A red iron(II) 4,4′-dicarboxy-2,2′-bipyridine complex ([Fe^II(dcbpy)₃]) was investigated as an extraordinary Fenton catalyst capable of activating much more molecular O₂ to mineralize organic pollutants in water at biocompatible pH values under visible irradiation. Eight representative organic pollutants were effectively degraded in the presence of this catalyst with high turnover number (368−2000). The flexible bifunctional coordination mode (N donor for ferrous ion and O donor for ferric form) devoted by the ligand dcbpy should be responsible for the preservation of iron(II/III) catalysis in such a neutral pH condition, whereas any substitution of the 4,4′-carboxylic groups in …

Sensitization Of Titania Semiconductor: A Promising Strategy To Utilize Visible Light, Zhaohui Wang, Wanhong Ma, Chuncheng Chen, Jincai Zhao

Dr Zhaohui Wang

No abstract provided.

Comparative Study Of Interaction Between Pyrite And Cysteine By Thermogravimetric And Electrochemical Techniques, Zhaohui Wang, Xuehui Xie, Shengmu Xiao, Jianshe Liu

Dr Zhaohui Wang

Adsorption mechanism of l-cysteine on pyrite was investigated by thermogravimetric and electrochemical techniques. TG curves provided the direct evidence for chemisorption of cysteine on pyrite surface. Once cysteine adsorbed to pyrite surface, Ecorr (corrosion potential) sharply lowered whereas Icorr (corrosion current) increased rapidly. Pyrite became more susceptible to be oxidized even at lower potential as cysteine was added. However, the mechanism for pyrite oxidation does not fundamentally change, although cysteine can obviously accelerate oxidation rate of pyrite. These findings have important implications for understanding the mechanism of bacterial adhesion to pyrite and even metal sulfide bioleaching.

Effects Of Chloride Ion On Degradation Of Acid Orange 7 By Sulfate Radical-Based Advanced Oxidation Process: Implications For Formation Of Chlorinated Aromatic Compounds, Ruixia Yuan, Sadiqua Ramjaun, Zhaohui Wang, Jianshe Liu

Dr Zhaohui Wang

Sodium chloride is a common salt used during textile wet processes. Here a dual effect of chloride (i.e. inhibitory and accelerating effect) on azo dye (Acid Orange 7, AO7) degradation in an emerging cobalt/peroxymonosulfate (Co/PMS) advanced oxidation process (AOP) was reported. Compared to OH-based AOPs, high concentrations of chloride (>5 mM) can significantly enhance dye decoloration independent of the presence of the Co2+ catalyst, but did greatly inhibit dye mineralization to an extent which was closely dependent upon the chloride content. Both UV–vis absorbance spectra and AOX determination indicated the formation of some refractory byproducts. Some chlorinated aromatic compounds, …

Light-Assisted Decomposition Of Dyes Over Iron-Bearing Soil Clays In The Presence Of H2o2, Zhaohui Wang, Wanhong Ma, Chuncheng Chen, Jincai Zhao

Dr Zhaohui Wang

Four types of soil clays from different sites in China have been chosen to simulate chemical remediation of soils contaminated with dyes by light-assisted Fenton-like method. X-Ray diffraction (XRD), X-ray photoelectron spectroscopic (XPS) and electron spin resonance (ESR) measurements indicated that these soil clays contain iron oxides such as magnetite and hematite, where nondistorted iron active sites (ESR spectra, g = 2.3) predominate. Upon visible or UV irradiation, the soil clays were very effective for the degradation of nonbiodegradable cationic dyes such as Rhodamine B (RhB) by activating H₂O₂ at neutral pH. The photodegradation rates of RhB …

Photochemical Cycling Of Iron Mediated By Dicarboxylates: Special Effect Of Malonate, Zhaohui Wang, Chen Xi, Hongwei Ji, Wanghong Ma, Chuncheng Chen, Jincai Zhao

Dr Zhaohui Wang

Photochemical redox cycling of iron coupled with oxidation of malonate (Mal) ligand has been investigated under conditions that are representative of atmospheric waters. Malonate exhibited significantly different characteristics from oxalate and other dicarboxylates (or monocarboxylates). Both strong chelating ability with Fe(III) and strong molar absorptivities, but much low efficiency of Fe(II) formation (ΦFe(II) = 0.0022 ± 0.0009, 300−366 nm) were observed for Fe(III)−Mal complexes (FMCs). Fe(III) speciation calculation indicated that Mal is capable of mediating the proportion between two photoactive species of Fe(III)−OH complexes and FMCs by changing the Mal concentration. Spin-trapping electron spin resonance (ESR) experiments proved the formation …

Adsorption Behavior Of Glucose On Pyrite Surface Investigated By Tg, Ftir And Xrd Analyses, Zhaohui Wang, Xuehui Xie, Shengmu Xiao, Jianshe Liu

Dr Zhaohui Wang

The interaction of glucose with pyrite has been investigated by a series of surface analyses, such as amounts adsorbed, TG, FTIR and XRD measurements. The adsorption experiment reveals that glucose would rapidly adsorb on the pyrite surface within 60 min. However, physical adhesion characterized as multi-molecular layer adsorption may occur based on adsorption isotherm type. All results obtained by TG and FTIR suggest that no adsorption took place after several times of washing. XRD results indicate that crystal structure of pyrite was not obviously destructed after glucose was added. The interplane distances of (111), (400) after interaction between glucose and …

Photochemical Coupling Reactions Between Fe(Iii)/Fe(Ii), Cr(Vi)/Cr(Iii) And Polycarboxylates: Inhibitory Effect Of Cr Species, Zhaohui Wang, Wanhong Ma, Chuncheng Chen, Jincai Zhao

Dr Zhaohui Wang

The roles of chromium species on photochemical cycling of iron and mineralization of polycarboxylates are examined in the presence of Cr(VI) or Cr(III) at pH 2.2−4.0. Under UV irradiation, Cr(III) altered the redox equilibrium of iron species, leading to the shift of the photosteady state toward Fe(II). After a longer time of illumination, total organic carbon (TOC) approached a steady state in the presence of Cr(III) or Cr(VI), whereas oxalate was thoroughly mineralized in the absence of Cr species. The TOC of steady state was closely related to the kind of polycarboxylates, Cr species dosages, pH and O2 atmosphere, but …

Probing Paramagnetic Species In Titania-Based Heterogeneous Photocatalysis By Electron Spin Resonance (Esr) Spectroscopy- A Mini Review, Zhaohui Wang, Wanhong Ma, Chuncheng Chen, Hongwei Ji, Jincai Zhao

Dr Zhaohui Wang

Many paramagnetic species such as active surface sites, reactive oxygen species (ROS) and organic radicals derived from the photodegradation of organics were involved in the heterogeneous photocatalysis. Identification and characterization of these paramagnetic species are essentially conducted using electron spin resonance (ESR) techniques, which can provide a detailed understanding of the radical composition and structure on the basis of the unique feature of g, hyperfine, and superhyperfine tensors for each kind of radicals of interest. In the present review, the basic theoretical principles of the ESR technique and its application in the field of TiO2-based heterogeneous photocatalysis are generally summarized. …

Degradation Of Reactive Dyes By Contact Glow Discharge Electrolysis In The Presence Of Cl− Ions: Kinetics And Aox Formation, Sadiqua Ramjaum, Ruixia Yuan, Zhaohui Wang, Jianshe Liu

Dr Zhaohui Wang

The plasma generated around the anode during contact glow discharge electrolysis (CGDE) is a rich source of hydroxyl (OH) radicals that can efficiently degrade organic contaminants in aqueous solutions. The degradation of textile azo dyestuffs, Reactive Yellow 176 (Y3RS), Reactive Red 239 (R3BS) and Reactive Black 5 (B5), by anodic CGDE was investigated in the presence of chloride (Cl⁻) ions. The degradation kinetics of the dyes was dependent on the concentration of Cl⁻ ions and on the respective dye being treated. R3BS degradation was inhibited by Cl⁻ ions in the range of 0–0.01 M. When the …

Effects Of Chloride Ions On Bleaching Of Azo Dyes By Co2+/Oxone Regent: Kinetic Analysis, Zhaohui Wang, Ruxia Yuan, Yaoguang Guo, Lei Xu, Jinashe Liu

Dr Zhaohui Wang

Orange II (Org II), one of the most common used azo dyes, was taken as a model to investigate the effects of chloride ion on dye decoloration in cobalt/peroxymonosulfate (Co/PMS) system. A significant decrease in the rate of Org II decoloration was observed upon addition of Cl⁻ (0.05–10 mM), but further addition of Cl⁻ (>50 mM) apparently accelerated dyes degradation. This dual effect of chloride on dyes bleaching was also observed as other halide ions (e.g. Br⁻, I⁻) or other azo dyes were present in Co/PMS system. In the Co-free PMS solutions, 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 …

The Evolution Of A Coastal Peatland At Byron Bay, Australia: Multi-Proxy Evidence From The Microfossil Record, Kathryn Taffs, Brendan Logan, Jeffrey Parr, Geraldine Jacobsen

Jeffrey Parr

This impressive collection celebrates the work of Peter Kershaw, a key figure in the field of Australian palaeoenvironmental reconstruction. Over almost half a century his research helped reconceptualize ecology in Australia, creating a detailed understanding of environmental change in the Late Pleistocene and Holocene. Within a biogeographic framework one of his exceptional contributions was to explore the ways that Aboriginal people may have modified the landscape through the effects of anthropogenic burning. These ideas have had significant impacts on thinking within the fields of geomorphology, biogeography, archaeology, anthropology and history. Papers presented here continue to explore the dynamism of landscape …

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 …

Determination Of The Cec In Srs Soils And The Capability Of Epa Model 9081 For Cec Of Acidic Soils, Alexandra Simpson

Alexandra M Simpson

No abstract provided.

Determination Of The Cec In Srs Soils And The Capability Of Epa Model 9081 For Cec Of Acidic Soils, Alexandra Simpson

Alexandra M Simpson

No abstract provided.