Girish Choppala

The University of Newcastle, Australia

This study explores interactions between As and Fe(III) minerals, predominantly schwertmannite and jarosite, in acid mine drainage (AMD) via observations at a former mine site combined with mineral formation and transformation experiments. Our objectives were to examine the effect of As on Fe(III) mineralogy in strongly acidic AMD while also consid...

The environmental chemistry of Cr is of widespread interest due to the hazardous nature of Cr(VI). Due to similar atomic size and charge, CrVIO4²⁻ can substitute for SO4²⁻ within schwertmannite - an Fe(III) oxyhydroxysulfate mineral that occurs widely in acidic and sulfate-rich systems. The presence of aqueous Fe(II) can induce transformation of sc...

Antimony (Sb) is a toxic metalloid that has been listed as a priority pollutant. The environmental impacts of Sb have recently attracted attention, but its phytotoxicity and biological transformation remain poorly understood. In this study, Sb speciation and transformation in plant roots was quantified by Sb K-edge X-ray absorption spectroscopy. In...

Tooeleite [FeIII6(AsIIIO3)4SO4(OH)4.4H2O] is an important As(III) host phase in diverse mining-impacted environments. Tooeleite has also received attention as a target phase for immobilizing As(III) in environmental and engineered settings. However, little is known regarding tooeleite’s environmental stability, with no previous research examining t...

This study examines incorporation of Sb(V) into schwertmannite─an Fe(III) oxyhydroxysulfate mineral that can be an important Sb host phase in acidic environments. Schwertmannite was synthesized from solutions containing a range of Sb(V)/Fe(III) ratios, and the resulting solids were investigated using geochemical analysis, powder X-ray diffraction (...

Selenium (Se) is an essential micronutrient in humans that is required for both physical and mental well-being. Low Se content in food crops is linked to Se-deficient soils globally. The aim of this study was examined the influence of sulfur (S) on the speciation and accumulation of selenium (Se) in three wheat cultivars grown in Se-deficient soils...

Dietary selenium (Se) deficiency is a well-known global problem originating from food crops grown in Se-deficient soil. Agronomic Se biofortification is one of the suitable options to minimize Se deficiency. Sulfur (S) is chemically similar to Se, and the role of S on the uptake and transformation of Se in grain has not been resolved. Considering t...

Understanding the transport behaviour of arsenic (As) from soils to humans is critical when undertaking human health risk assessment and contamination control. This research examined As bioaccessibility in different As fractions and particle size fractions of As-enriched mine soils using different extractions. Bioaccessibility of As ranged from 0.2...

Metallic anions including antimonate (SbV), arsenate (AsV), chromate (CrVI), molybdate (MoVI), selenate (SeVI), tungstate (WV) and vanadate (VV) are important pollutants in the terrestrial environment due to their impacts on human and ecological health. It is essential that appropriate assays are used for derivation of toxicity models and guidance...

Naturally arsenic (As) enriched agricultural soils represent a significant global human health risk. In this study, As fractionation and mineralogy were investigated in naturally As-enriched agricultural soils and their corresponding sand, silt and clay fractions. Median As increased generally in the order (mg/kg)∶ silt (280) bulk (314) sand (323)<...

Rhizoremediation is increasingly becoming a green and sustainable alternative to physico-chemical methods for remediation of contaminated environments through the utilization of symbiotic relationship between plants and their associated soil microorganisms in the root zone. The overall efficiency can be enhanced by identifying suitable plant-microb...

Trace elements contamination from abandoned mine sites is a major threat to the environment. The distribution of trace elements in various particle sizes fractions of soils from abandoned mine sites plays a critical role in designing remediation approaches. This study investigated the geochemical distribution of trace element enrichment and mineral...

Mixed Cr(III)-Fe(III) (oxy)hydroxides are important Cr-bearing phases in natural, unpolluted soil. Fires frequently affect large areas of land around the world, causing the temporary development of elevated soil temperatures. This study examines the hypothesis that heating Cr(III)-Fe(III) (oxy)hydroxides at temperatures which occur in surface soils...

Abstract The Fe(II)-induced transformation of ferrihydrite, a potent scavenger for antimony (Sb), can considerably influence Sb mobility in reducing soils, sediments and groundwater systems. In these environments, humic acids (HA) are prevalent, yet their influence on Sb behaviour during ferrihydrite transformation is poorly understood. In this stu...

Fire-induced oxidation of Fe oxide-bound Cr(III) may represent a largely unexplored, yet globally-significant pathway for the natural formation of hazardous Cr(VI) in soil.

This study aimed to investigate the potential of energy crops for biomethane production by examining the influence of abattoir and municipal wastewater irrigation on biomass production and the Biochemical Methane Potential (BMP). The experiments covered seven energy crops including sugar beet, alfalfa, maize, giant reed, napier grass, sunflower and...

Schwertmannite is an Fe(III)-oxyhydroxysulfate which is common in acid mine drainage (AMD) and acid sulfate soil (ASS) environments. Natural schwertmannite is often enriched in Cr(III), yet the effects of Cr(III) substitution on schwertmannite transformation to more stable Fe(III) minerals has not been addressed. Here we examine, for the first time...

Chemical composition of the initial schwertmannites. (DOCX)

Linear combination fit results for XAS-derived solid-phase Fe speciation (%) during Fe(II) accelerated transformation of Cr(III) incorporated schwertmannite at 14 d. (DOCX)

Relationship between the amount of schwertmannite (%) (quantified through Fe K-edge EXAFS) and 1 M HCl extractable Fe(III) (%) during Fe(II) accelerated transformation at 14 d. (DOCX)

This guidance provides technical and procedural advice to assess and manage Monosulfidic Black Ooze (MBO) in waterways and wetlands. This guidance is aimed as an authoritative reference for natural resource managers, planners, policy makers and other practitioners. The guidance aims to help understand the complexities associated with MBOS, and pro...

Chromium(VI) is an environmental contaminant of priority concern, which can be treated by reduction of toxic Cr(VI) to non-toxic Cr(III). Siderite (FeCO3), an Fe(II)-containing mineral, occurs in many anaerobic sediments and groundwater systems and is extremely reactive, thus making it a potentially important host-phase in governing the fate and tr...

The increased use of estuarine waters for commercial and recreational activities is one consequence of urbanisation. Western Australia's Peel-Harvey Estuary highlights the impacts of urbanisation, with a rapidly developing boating industry and periodic dredging activity. The aim of this research is to evaluate the potential mobility of nutrients an...

Excessive use of chromium (Cr) in several industrial applications has a significant impact on soil biota. Chromium when present in soil and water occurs in two forms [Cr(III) and Cr(VI)] which exhibit contrasting characteristics and therefore retention of these two species is of prime importance to arrest Cr contamination in the environment. In thi...

The present work examines the utilisation potential of the bio-waste, chitosan for the remediation of soils contaminated with zinc (Zn). The mechanism involved was elucidated via a study of Zn sorption kinetics on pure and modified chitosan beads, the latter containing molybdate and phosphate compounds. The effect of equilibration time on adsorptio...

The last few decades have seen the rise of alternative medical approaches including the use of herbal supplements, natural products, and traditional medicines, which are collectively known as 'Complementary medicines'. However, there are increasing concerns on the safety and health benefits of these medicines. One of the main hazards with the use o...

Shooting range soils contain mixed heavy metal contaminants including lead (Pb), cadmium (Cd), and zinc (Zn). Phosphate (P) compounds have been used to immobilize these metals, particularly Pb, thereby reducing their bioavailability. However, research on immobilization of Pb’s co-contaminants showed the relative importance of soluble and insoluble...

Pyrogenic carbon (PyC), the combustion residues of fossil fuel and biomass, is a versatile soil fraction active in biogeochemical processes. In this study, the chemo-thermal oxidation method (CTO-375) was applied to investigate the content and distribution of PyC in 30 Australian agricultural, pastoral, bushland and parkland soil with various soil...

Phytotoxicity of inorganic contaminants is influenced by the presence of competing ions at the site of uptake. In this study, interaction of soil pore-water constituents with arsenate toxicity was investigated in cucumber (Cucumis sativa L) using 10 contrasting soils. Arsenate phytotoxicity was shown to be related to soluble carbonate and phosphate...

Greenhouse gas (GHG) emissions from agricultural operations continue to increase. Carbon (C) enriched char materials like biochar have been described as a mitigation strategy. Utilization of biochar material as a soil amendment has been demonstrated to provide potentially greater soil GHG suppression due to its interactions in the soil system. Howe...

This study evaluated the effects of pure and modified chitosan beads on the remediation of zinc (Zn) polluted soils and estimated the bioavailability of Zn for Indian mustard plants. The soil was spiked with 0 to 400 mg kg-1 of Zn and subsequently amended with pure chitosan beads (PCB) and chitosan beads modified with molybdenum (MoCB), iron (ICB),...

This study was conducted to evaluate the effect of equilibration time on adsorption of zinc [Zn(II)] and nickel [Ni(II)] on pure and modified chitosan beads. The initial adsorption of Zn(II) was high on molybdenum (Mo)-impregnated chitosan beads (MoCB) during the initial 60 min. However, after 240 min, Zn(II) adsorption occurred more on single supe...

In this work, the effects of various wastewater sources (storm water, sewage effluent, piggery effluent, and dairy effluent) on the reduction, and subsequent mobility and bioavailability of arsenate [As(V)] and chromate [Cr(VI)] were compared using both spiked and field contaminated soils. Wastewater addition to soil can increase the supply of carb...

Iron monosulfides are the initial iron sulfide minerals that form under reducing conditions in organic-rich sediments. Frequently referred as monosulfidic black ooze (MBO), these sediments exists in a range of anoxic systems including estuaries, coastal wetlands and permeable reactive barriers. The objective of this study was to investigate the tra...

The production of biosorbents and biochars from various biowastes (such as the agricultural and food industries and algal and fungal biomass) has received considerable attention because of their potential use in the removal and recovery of elements, such as precious metals and heavy metals from water and wastewater. Recovery of these metals from th...

Heavy metals such as chromium (Cr) and arsenic (As) occur in ionic form in soil, with chromate [Cr(VI)] and arsenate As(V) being the most pre-dominant forms. The application of biochar to Cr(VI) and As(V) spiked and field contaminated soils was evaluated on the reduction processes [(Cr(VI) to Cr(III)] and [As(V) to As(III))], and subsequent mobilit...

In this study, two carbon materials [chicken manure biochar (CMB) and black carbon (BC)] were investigated for their effects on the reduction of hexavalent chromium [Cr(VI)] in two spiked and one tannery waste contaminated soils. In spiked soils, both the rate and the maximum extent of reduction of Cr(VI) to trivalent Cr [Cr(III)] were higher in th...

Cadmium (Cd) is an inorganic mineral in the earth's crust. Cadmium entry into the environment occurs through geogenic and anthropogenic sources. Industrial activities including mining, electroplating, iron and steel plants, and battery production employ Cd during their processes and often release Cd into the environment. When disseminated into soil...

This report can be downloaded from the following link - http://www.environment.sa.gov.au/files/9cd6b205-f85c-4f7b-ae36-a42800b8b4b4/lower-lakes-rates-of-recovery-2013-14-rep.pdf

Phosphorus (P) management in agriculture is crucial for both environmental health and future availability of P resource. Application of P as fertilisers (organic or inorganic) often results in either P accumulation in soil or loss to water bodies, rendering them unavailable to crops. In this study, the mobility of inorganic (KH2PO4 (PP)) and organi...

Landfill remains the predominant means of waste disposal throughout the globe. Numerous landfills exist in developed and underdeveloped countries, engineered with contrasting degrees of effectiveness. Modern landfill closure in developed countries involves the conventional capping of waste with materials such as compacted clay or geosynthetic clay...

Biochar has great potential as a soil amendment to immobilize heavy metals, thereby reducing their bioavail-ability. In this study, biochars derived from chicken manure and green waste were compared with commercial activated carbon (AC) and laboratory produced black carbon (BC) for the sorption of Pb and Cd. Sorption kinetics and equilibrium sorpti...

This study was aimed to examine the efficiency of a novel bacterial consortium on the reduction of toxic hexavalent chromium [Cr(VI)] to non-toxic trivalent Cr [Cr(III)]. Six Cr(VI)-resistant bacteria (IS1-IS6) were isolated from a tannery waste disposal site at Mount Barker, South Australia, of which three viz., IS1, IS2 and IS3 were selected base...

The sorption of chromium (Cr) species to soil has become the focus of research as it dictates the bioavailability and also the magnitude of toxicity of Cr. The sorption of two environmentally important Cr species [Cr(III) and Cr(VI)] was examined using batch sorption, and the data were fitted to Langmuir and Freundlich adsorption isotherms. The eff...

Landfill remains the predominant means of waste disposal throughout the globe. Numerous landfills exist in developed and underdeveloped countries, engineered with contrasting degrees of effectiveness. Modern landfill closure in developed countries involves the conventional capping of waste with materials such as compacted clay or geosynthetic clay...

In farming systems, all the applied phosphorus (P) is not available to plants because they are either adsorbed in soil or lost to the environment through leaching or runoff. The effect of coal combustion products (CCPs) for enhancing the bioavailability of applied phosphorus (P) in soil was examined separately for inorganic (KH2PO4 - PP) and organi...

Chromium reaches the soil environment through waste disposal emanating from a number of industrial activities, including coal-fired power production, electroplating, leather tanning, timber treatment, pulp production, and mineral ore and petroleum refining. Of the heavy metals, chromium (Cr) is a major pollutant, poses a great threat to flora and f...

Phosphorus (P) influences arsenic (As) mobility and bioavailability which depends on the charge components of soil. The objective of this study was to examine P-As interaction in variable-charge allophanic soils in relation to P-induced As mobilization and bioavailability. In this work, the effect of P on arsenate [As(V)] adsorption and desorption...

Chromium toxicity in soils can be mitigated by reduction of Cr(VI) to Cr(III) which is influenced by the presence of free Cr(VI) species in soil solution, and the supply of protons and electrons. In this study, the effects of Cr(VI) adsorption (i.e. availability of free Cr(VI) species in soil solution), soil pH (i.e. supply of protons) and three el...

The term “trace elements” generally includes elements (both metals and metalloids) that occur in natural and perturbed environments in small amounts and that, when present in sufficient bioavailable concentrations, are toxic to living organisms (Adriano 2001). This group includes both biologically essential [e.g., cobalt (Co), copper (Cu), chromium...

The widespread use of chromium (Cr) has a deleterious impact on the environment. A number of pathways, both biotic and abiotic in character, determine the fate and speciation of Cr in soils. Chromium exists in two predominant species in the environment, trivalent [(Cr(III)] and hexavalent [Cr(VI)]. Of these two forms, Cr(III) is non-toxic and is st...

There have been increasing interests in the conversion of organic residues into biochars in order to reduce the rate of decomposition, thereby enhancing carbon (C) sequestration in soils. However energy is required to initiate the pyrolysis process during biochar production which can also lead to the release of greenhouse gasses. Alternative method...

Background and aims Biochar has attracted research interest due to its ability to increase the soil carbon pool and improve crop productivity. The objective of this study was to evaluate the metal immobilizing impact of chicken manure- and green waste-derived biochars, and their effectiveness in promoting plant growth. Methods The immobilization an...

Background and aims: Biochar has attracted research interest due to its ability to increase the soil carbon pool and improve crop productivity. The objective of this study was to evaluate the metal immobilizing impact of chicken manure- and green waste-derived biochars, and their effectiveness in promoting plant growth. Methods: The immobilization...

As land application becomes one of the important waste utilization and disposal practices, soil is increasingly being seen as a major source of metal(loid)s reaching food chain, mainly through plant uptake and animal transfer. With greater public awareness of the implications of contaminated soils on human and animal health there has been increasin...