It is our privilege to dedicate this book on Contaminants and the Soil Environment to Kevin Tille... more It is our privilege to dedicate this book on Contaminants and the Soil Environment to Kevin Tiller who was our leader and great inspiration for the present contaminant research team at CSIRO Division of Soils and the Cooperative Research Centre for Soil and Land Management. Dr Tiller, a leading international soil scientist on heavy metal contaminants in the soils, died after a short illness in Adelaide. He was born at Pinnaroo, South Australia. Following BSc and MSc degrees in Chemistry from the University of Adelaide, he travelled to the USA to study for his doctorate at Cornell University. After the completion of his PhD degree he returned to CSIRO and initially studied the reactions of trace metals in agricultural soils. During the 1970s Dr Tiller turned his attention to heavy metal pollution, plant micronutrients and the problem of cadmium and lead affecting the quality of agricultural products. His pioneering research into lead levels in the Port Pirie area and the effect of heavy metals on crop quality has had significant impact on Australian health and regulatory controls on food and soil quality. He was the recognised national leader in environmental pollution by heavy metals and an international authority whose opinion was frequently sought and highly regarded. His contributions to environmental research are recognised by the many invitations that he received to lecture at major international conferences and meetings throughout the world. Dr Tiller recognised the need for contaminants research in Australia long before it was publicly acknowledged as a serious problem. His foresight led to the development of much of the current research in Australia on soil contaminants. Kevin's untimely death was a great loss to CSIRO, Australia and the international scientific community.
The bioavailability of organic chemicals in soil and sediment is an important area of scientific ... more The bioavailability of organic chemicals in soil and sediment is an important area of scientific investigation by environmental scientists, but it is still poorly understood by regulators and industry working in the environmental sector. Regulators are starting to consider bioavailability within retrospective risk assessment frameworks for organic chemicals: by doing this, realistic decision-making on polluted environments is achievable, rather than relying on the traditional approach of using total extractable concentrations. However, implementation is not straightforward because the developments of bioavailability science have not always been translated into ready-to-use approaches for regulators. Similarly, bioavailability still remains largely unexplored within prospective regulatory frameworks dealing with approval and regulation of organic chemicals. This article discusses bioavailability concepts and methods, as well as possible pathways for the implementation of bioavailabil...
Different soil–water conditions regulate sorption–desorption phenomena of beryllium at a legacy w... more Different soil–water conditions regulate sorption–desorption phenomena of beryllium at a legacy waste disposal site.
Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are persistent organic contaminants of conce... more Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are persistent organic contaminants of concern to human and environmental health. Several literature reviews and laboratory column experiments have been conducted to determine the transport parameters and to describe the fate of PFAS as they migrate in subsurface environments. However, there are very few case studies focusing on contaminated sites with high-resolution field data. Such studies are crucial for the validation of transport simulation models that have been developed from experimental studies, prior to their broader applications. The key purpose of this research was to evaluate lithological separations of PFAS fractions as they are transported in the vadose zone of a historically (1979) contaminated site where Aqueous Film Forming Foam (AFFF) formulations (3M Lightwater™ and Ansulite™) have been used for fire training exercises. Surface and subsurface soils, and groundwater samples were collected across the site and a t...
Context Cadmium (Cd) toxicity and zinc (Zn) deficiency are of major concerns for crop growth and ... more Context Cadmium (Cd) toxicity and zinc (Zn) deficiency are of major concerns for crop growth and quality. Moreover, their interactive effects exert some controversial reports. Aims The effects of zinc oxide nanoparticles (ZnO NPs) and Cd on growth, physiology, and metal distribution in mung beans (Vigna radiata L.) was investigated. Methods Seven-day-old seedlings were treated with Zn (0, 1, 2, 4, 8, 16 and 32 μM) and Cd (0, 0.5, 1 μM) for 14 days. Key results Photosynthetic pigments, antioxidant enzyme activities, dry matter yield and metal concentration in tissues were significantly influenced by ZnO NPs and Cd. Considered on its own as a main effect, Zn application (16 μM) enhanced its accumulation in roots, stem and leaf by about 33-fold (314 mg kg−1), 10-fold (60.6 mg kg−1) and 17-fold (110.8 mg kg−1), respectively, compared to control. However, accumulation was slower for interactions with Cd. While leaf Zn increased approximately 27 times (180 mg kg−1) at 32 μM Zn, its intera...
Organically modified clays have attracted increasing research attention for their various commerc... more Organically modified clays have attracted increasing research attention for their various commercial and industrial applications, such as being carriers for pesticide delivery. Besides, the suitability and performance of commercially available organoclays could further promote their applicability. Hence, this study investigated the potential application of a commercially available alkylamine-modified montmorillonite (MMT) nanoclay as a carrier for a widely used insecticide, imidacloprid. X-ray diffraction and thermogravimetric analysis were employed to illustrate the arrangement, orientation, and conformation of surfacemodifying agents (SMAs) on MMT nanoclay. It was observed that the clay was modified at an ∼1.0 cation exchange capacity, with the SMAs, especially octadecylamine, arranged in the MMT nanoclay as a bilayer to a pseudo-trilayer or a paraffin monolayer with a tilting angle of ∼25°, which indicated the nanoclay's ability to adsorb a large amount of imidacloprid. The adsorption−desorption of imidacloprid to MMT nanoclay further confirmed this applicability. A high adsorption capacity (∼85 mg g −1) was observed, with a high reversibility in desorption, showing a hysteresis value of 0.75. Further, the adsorption kinetics and response of the nanoclay to imidacloprid revealed that, initially, a rapid sorption occurred due to a hydrophobic interaction. This was followed by a slower diffusion-controlled sorption due to hydrogen bonding to the internal binding sites. The releasing pattern of imidacloprid from the MMT nanoclay indicated its potential for the preparation of a slow-releasing pesticide formulation where the nanoclay will reduce the instantaneous release of the total amount of pesticide.
Behaviour of heavy metals and their management to remediate and avoid agricultural soil contamina... more Behaviour of heavy metals and their management to remediate and avoid agricultural soil contamination
Zhaomin Dong, CuiXia Liu, Yanju Liu, Kaihong Yan, Kirk T. Semple and Ravi Naidu* 4 5 a Global Cen... more Zhaomin Dong, CuiXia Liu, Yanju Liu, Kaihong Yan, Kirk T. Semple and Ravi Naidu* 4 5 a Global Centre for Environmental Remediation, the Faculty of Science and Information Technology, 6 University of Newcastle, University Drive, Callaghan, NSW 2308, Australia 7 b Cooperative Research Centre for Contamination Assessment and Remediation of the Environment 8 (CRC CARE), Mawson Lakes, SA 5095, Australia 9 c School of Environmental Science and Engineering, Huazhong University of Science and Technology, 10 Wuhan 430074, China 11 d Lancaster Environment Centre, Lancaster University, LA1 4YQ Lancaster, United Kingdom 12 13 * Corresponding Author: Ravi Naidu 14 15 ATC Building, Global Center for Environmental Remediation, Faculty of Science and Information 16 Technology, University of Newcastle, Callaghan, NSW 2308 17
Nutrient pollution of surface water, such as excess phosphate loading on lake surface water, is a... more Nutrient pollution of surface water, such as excess phosphate loading on lake surface water, is a significant issue that causes ecological and financial damage. Despite many technologies that can remove available phosphate, such as material-based adsorption of those available phosphate ions, the development of a material that can trap them from the surface water is worth doing, considering other aspects. These aspects are: (i) efficient adsorption by the material while it settles down to the water column, and (ii) the material itself is not toxic to the lake natural microorganism. Considering these aspects, we developed a trace lanthanum-grafted surface-modified palygorskite, a fibrous clay mineral. It adsorbed a realistic amount of phosphate from the lake water (typically 0.13–0.22 mg/L). The raw and modified palygorskite (Pal) includes unmodified Australian Pal, heated (at ~400 °C) Pal, and acid (with 3 M HCl)-treated Pal. Among them, while acid-treated Pal grafted a lower amount ...
Environmental Science and Pollution Research, 2020
The levels of trace elements (As, Hg, Cr, Cd, Pb, Co, Ni, Cu, Mn and Zn) in commercially importan... more The levels of trace elements (As, Hg, Cr, Cd, Pb, Co, Ni, Cu, Mn and Zn) in commercially important fish species sampled from fish markets of Adelaide, Australia; canned fish from South Australian supermarkets; and fish markets of West Bengal, India were determined by inductively coupled plasma mass spectrometry (ICP-MS) after microwave digestion. Mercury was determined by using triple quadrupole ICP-MS. The accuracy of the methods was assessed with a certified standard reference material (NRCC-DORM-3 dogfish protein), and the results were compared with values reported in the literature. The results indicated considerable variations in the accumulation of trace elements among the fish species. The relationship between species with respect to trace element concentrations was examined using cluster analysis, which showed Indian fish species forming distinct groups from the others. Other than As in sardines, whiting and snapper and Hg in swordfish and snapper, the trace element concentrations were within permissible limits recommended by various standards. Based on the estimated daily intake (EDI), fish samples analysed in this study can be considered safe for human consumption as per the recommended daily dietary allowance limit fixed by various agencies. Continuous monitoring and assessments of fish metal(loid) content are needed to generate more data and safeguard human health.
The fate and behaviour of polycyclic aromatic hydrocarbons (PAHs) in soil is of interest in the r... more The fate and behaviour of polycyclic aromatic hydrocarbons (PAHs) in soil is of interest in the risk assessment of contaminated lands and are usually based on determinations of fractions extracted from soil. For decades, either single or sequential solvent extractions have been used to determine PAH extractability in soils; however, there is a lack of certainty as to which fractions are being extracted by these techniques. This study is the first report of changes and similarities in extractability of benzo[a]pyrene (B[a]P) in four contrasting soils (sandy loam, loamy sand, clayey loam, and sandy) when determined, simultaneously using both single (dichloromethane-DCM/acetone-Ace mixture) and sequential solvent (butanol followed by DCM/Ace) extractions. Residues after extraction were subjected to methanolic saponification (MeKOH). Butanol (BuOH)-and total-extractability of B[a]P, following sequential solvent extraction, decreased significantly (p < 0.05) with time after addition of B[a]P. The decrease in BuOH extractability was particularly marked in the organic matter-rich clayey loam soil which also had the largest (> 40%) amounts of non-extractable residues. The cumulative amounts of B[a]P extracted in each soil by single and sequential solvent extractions were similar (p > 0.05) at each aging period, which indicate access to similar B[a]P fractions in soil by both solvent extractions. The similarity in the amounts of B[a]P non-extractable residues recovered by MeKOH of pre-extracted soils, through either of the extraction methods, confirms that the total-extractable B[a]P fractions from both methods are similar.
Total and inorganic arsenic (As) content in rice and rice-based diets (n=59) obtained from superm... more Total and inorganic arsenic (As) content in rice and rice-based diets (n=59) obtained from supermarkets in South Australia were studied to investigate the contamination levels and whether consumption of these products pose potential health risks to young children and adults. Results show that of the 59 rice-based products, 31 (53 %) exceeded the EU recommended value (100 µg/kg) of As for young children and 13 (22%) samples had higher than maximum level of 200 µg/kg recommended for adults. Arsenic content varies as rice crackers > baby rice > rice cakes >puffed rice > other rice-based snacks > ready-to-eat rice. Of the 6 categories of ACCEPTED MANUSCRIPT rice-based products, except ready-to-eat rice, all others exceeded the EU recommended value for young children. Even manufacture recommended servings deliver significant amounts (0.56 to 6.87 µg) of inorganic As. These amounts are within the range of BMDL 01 values indicated by the European Food Safety Authority (EFSA), which means the risk cannot be avoided for young children and adults considering the levels of total and inorganic As in ricebased products.
Purpose A risk-based approach commonly applied for Pbcontaminated soil is stabilisation by phosph... more Purpose A risk-based approach commonly applied for Pbcontaminated soil is stabilisation by phosphate amendment. However, the proportion of Pb present in a form that is readily immobilised by phosphate addition is often limited. Chelates were examined as a means to mobilise Pb prior to immobilisation to increase the proportion of Pb that could react with phosphate. Four contrasting shooting range soils from around Australia (Murray Bridge (MB), Townsville (TV), Darwin (DA) and Perth (PE)) were used for the study. Materials and methods Chelating agents such as ethylenediaminetetraacetic acid (EDTA) are able to extract Pb from existing species in the soil, forming complexes. By lowering soil pH or adding Fe 3+ for the displacement of Pb from the complex, a greater proportion of Pb may be available for reaction with phosphate. The use of biodegradable ethylenediamine-N,N′-disuccinic acid (EDDS) minimises residual effects of chelate treatment in the soil. Results and discussion EDTA was not found to be suitable due to the stability of the chelate-Pb complex. The addition of EDDS had variable effect between the four shooting range soils. In the strongly weathered oxidic TV and DA soils, applying EDDS prior to phosphate amendment produced greater reduction in bioaccessible Pb, but in the less weathered MB and PE soil, bioaccessible Pb was increased. Water-extractable (WE) Pb increased in the soils by EDDS application, but this could be offset by lime application in DA soil, without negatively affecting Pb bioaccessibility; WE Pb also decreased over time when ammonium nitrate was added to the soil. Conclusions Application of EDDS may be able to increase the proportion of Pb that reacts with phosphate in the soil, providing greater reduction in bioaccessible Pb than phosphate-only treatments. Additional treatability studies are needed to test amendments that could manage the water-extractable portion of Pb and to optimise application of EDDS for the best outcome.
Activated biocarbons with a porous structure and nitrogen functionalities are synthesized from th... more Activated biocarbons with a porous structure and nitrogen functionalities are synthesized from the prolific waste biomass, Arundo donax, and an organic material, chitosan, by a simple one step chemical activation with ZnCl2.
Journal of colloid and interface science, Jan 15, 2014
Kaolinite supported bimetallic Fe/Ni nanoparticles (K-Fe/Ni) demonstrated capacity for simultaneo... more Kaolinite supported bimetallic Fe/Ni nanoparticles (K-Fe/Ni) demonstrated capacity for simultaneous removal of both cationic and anionic contaminants such as Pb (II) and NO3(-). The dispersion of Fe/Ni nanoparticles was improved when kaolinite was used as a stabilizer, and also enhanced the reactivity of K-Fe/Ni. The adsorption of Pb (II) onto the kaolinite and the consequent simultaneous catalytic reduction of Pb (II) and NO3(-) kaolinite were confirmed by SEM, BET, EDS, XRD and batch adsorption-reduction test. Orthogonal method showed that initial concentrations of Pb (II) and NO3(-), as well the dosage of K-Fe/Ni showed the most significant impact on the removal rates, where 86.3% of Pb (II) and 73.6% of NO3(-) was removed at optimized conditions. In addition, K-Fe/Ni could be stored for 15 days in dry air without losing reactivity. Reusability test of K-Fe/Ni indicated that the removal efficiency decreased by 12.5% for Pb (II) and 27.2% for NO3(-) after using 3 times successivel...
The degradation of naphthalene using immobilized Bacillus fusiformis (BFN) strain on alginate-pol... more The degradation of naphthalene using immobilized Bacillus fusiformis (BFN) strain on alginate-polyvinyl alcohol (PVA)-clays bead was much higher than that of using a freely suspended BFN strain. This was due to the beads facilitating biodegradation by enhancing concentration of naphthalene using the beads as an adsorbent in the cells' vicinity. This was confirmed by the kinetics of naphthalene on the beads, where its adsorption onto the beads was confirmed by pseudo-second-order kinetics. The biodegradation of naphthalene fitted well to the first-order rate model. More than 99.7% of naphthalene which was removed within 12 h, contained bentonite 2% (w/v), PVA 12% (w/v), alginate 0.3% (w/v) and 10% (v/v) initial biomass loading. Scanning electron microscopy (SEM) of the beads showed that Bacillus fusiformis was evenly distributed within them. Storage stability and reusability results revealed that the ability to degrade naphthalene using beads with immobilized cells remained stable after storage at 4 0 C for 35 days and being reused 8 times (12 days), respectively. Furthermore the naphthalene degradation rate of immobilized cells was maintained (94.3%) at the eighth cycle.
Journal of agricultural and food chemistry, Jan 25, 2014
Rice is an important route of arsenic (As) exposure to humans, especially populations with rice-b... more Rice is an important route of arsenic (As) exposure to humans, especially populations with rice-based diets. Human health risk of As varies greatly with rice variety and country of origin. The purpose of the present study was to determine total and speciated As in Australian-grown and imported rice on sale in Australia to assess their health risk to consumers. The total As (tAs) concentrations in Australian-grown organic brown, medium grain brown, and organic white rice were 438±23, 287±03, and 283±18 μg kg(-1) dry weight (d wt), respectively. In Bangladeshi, Indian, Pakistani, and Thai rice imported and on sale in Australia, tAs concentrations were 56±05, 92±10, 82±06 and 172±24 μg kg(-1), respectively. Asian rice contained mainly inorganic As (iAs; 86-99%), whereas 18-26% of the tAs in Australian-grown rice was dimethylarsinic acid (DMA). Relatively higher concentrations of tAs in Australian-grown rice than that in imported rice of Asian origin suggest that Australian-grown rice m...
ABSTRACT This work evaluated surfactant-enhanced in situ chemical oxidation (S-ISCO) in a hydroca... more ABSTRACT This work evaluated surfactant-enhanced in situ chemical oxidation (S-ISCO) in a hydrocarbon-contaminated soil. Surfactants and efficacy of oxidant activation as well as the treatability of contaminated soil were assessed. The surfactant VeruSOL-3 with a critical micelle concentration (CMC) of 5.5 g/L was selected. Based on the results, activated oxidations by sodium persulphate and hydrogen peroxide were able to effectively destroy target organic compounds in emulsion and soil. The destruction of total petroleum hydrocarbon (TPH) in emulsion was completed in 14 days and polycyclic aromatic hydrocarbons (PAHs) in excess of 96 %. Green nanoiron was much more active than other activators in emulsion. The data also indicates that oxidation using activators was much less pronounced in soil matrices. However, it is expected that given sufficient dose and treatment time, a higher destruction rate in the contaminated soil can be achieved. The study showed that the remediation of target organic contaminants (TPH, PAH) in soil by S-ISCO using activated sodium persulphate is feasible.
Journal of Liquid Chromatography & Related Technologies, 2003
... via control of the BGE pH to obtain reasonable selectivity.1–3 View all references Organic mo... more ... via control of the BGE pH to obtain reasonable selectivity.1–3 View all references Organic modifiers, such as organic solvents and large hydrophobic cations, can also alter the EOF by altering the charge density at the surface of the fused‐silica capillary.[4]4. Sarmini, K. and ...
Indirect UV detection in capillary zone electrophoresis (CZE) is frequently used for the determin... more Indirect UV detection in capillary zone electrophoresis (CZE) is frequently used for the determination of inorganic anions and carboxylic acids. However, there are few reports on direct UV detection of these solutes in real samples. This paper describes the use of direct UV detection of inorganic anions and organic acids in environmental samples using co-electroosmotic capillary zone electrophoresis (co-CZE) at 185 nm. The best separation and detection of the solutes was achieved using a fused silica capillarywith an electrolyte containing 25 mM phosphate, 0.5 mM tetradecyltrimethylammonium bromide (gAB) and 15% acetonitrile (v/v) at pH 6.0. Four common inorganic anions (CI-, NO2-, NO3-and SO42-) and 11 organic acids (oxalic, formic, fumaric, tartaric, malonic, malic, citric, succinic, maleic, acetic, and lactic acid), were determined simultaneously in 15 min. Linear calibration plots for the test solutes were obtained in the range 0.02-0.5 mM with detection limits ranging from 1-9 I~M depending on the analyte. The proposed method was successfully used to determine inorganic anions and carboxylic acids in soil and plant tissue extracts with direct injection of the sample.
It is our privilege to dedicate this book on Contaminants and the Soil Environment to Kevin Tille... more It is our privilege to dedicate this book on Contaminants and the Soil Environment to Kevin Tiller who was our leader and great inspiration for the present contaminant research team at CSIRO Division of Soils and the Cooperative Research Centre for Soil and Land Management. Dr Tiller, a leading international soil scientist on heavy metal contaminants in the soils, died after a short illness in Adelaide. He was born at Pinnaroo, South Australia. Following BSc and MSc degrees in Chemistry from the University of Adelaide, he travelled to the USA to study for his doctorate at Cornell University. After the completion of his PhD degree he returned to CSIRO and initially studied the reactions of trace metals in agricultural soils. During the 1970s Dr Tiller turned his attention to heavy metal pollution, plant micronutrients and the problem of cadmium and lead affecting the quality of agricultural products. His pioneering research into lead levels in the Port Pirie area and the effect of heavy metals on crop quality has had significant impact on Australian health and regulatory controls on food and soil quality. He was the recognised national leader in environmental pollution by heavy metals and an international authority whose opinion was frequently sought and highly regarded. His contributions to environmental research are recognised by the many invitations that he received to lecture at major international conferences and meetings throughout the world. Dr Tiller recognised the need for contaminants research in Australia long before it was publicly acknowledged as a serious problem. His foresight led to the development of much of the current research in Australia on soil contaminants. Kevin's untimely death was a great loss to CSIRO, Australia and the international scientific community.
The bioavailability of organic chemicals in soil and sediment is an important area of scientific ... more The bioavailability of organic chemicals in soil and sediment is an important area of scientific investigation by environmental scientists, but it is still poorly understood by regulators and industry working in the environmental sector. Regulators are starting to consider bioavailability within retrospective risk assessment frameworks for organic chemicals: by doing this, realistic decision-making on polluted environments is achievable, rather than relying on the traditional approach of using total extractable concentrations. However, implementation is not straightforward because the developments of bioavailability science have not always been translated into ready-to-use approaches for regulators. Similarly, bioavailability still remains largely unexplored within prospective regulatory frameworks dealing with approval and regulation of organic chemicals. This article discusses bioavailability concepts and methods, as well as possible pathways for the implementation of bioavailabil...
Different soil–water conditions regulate sorption–desorption phenomena of beryllium at a legacy w... more Different soil–water conditions regulate sorption–desorption phenomena of beryllium at a legacy waste disposal site.
Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are persistent organic contaminants of conce... more Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are persistent organic contaminants of concern to human and environmental health. Several literature reviews and laboratory column experiments have been conducted to determine the transport parameters and to describe the fate of PFAS as they migrate in subsurface environments. However, there are very few case studies focusing on contaminated sites with high-resolution field data. Such studies are crucial for the validation of transport simulation models that have been developed from experimental studies, prior to their broader applications. The key purpose of this research was to evaluate lithological separations of PFAS fractions as they are transported in the vadose zone of a historically (1979) contaminated site where Aqueous Film Forming Foam (AFFF) formulations (3M Lightwater™ and Ansulite™) have been used for fire training exercises. Surface and subsurface soils, and groundwater samples were collected across the site and a t...
Context Cadmium (Cd) toxicity and zinc (Zn) deficiency are of major concerns for crop growth and ... more Context Cadmium (Cd) toxicity and zinc (Zn) deficiency are of major concerns for crop growth and quality. Moreover, their interactive effects exert some controversial reports. Aims The effects of zinc oxide nanoparticles (ZnO NPs) and Cd on growth, physiology, and metal distribution in mung beans (Vigna radiata L.) was investigated. Methods Seven-day-old seedlings were treated with Zn (0, 1, 2, 4, 8, 16 and 32 μM) and Cd (0, 0.5, 1 μM) for 14 days. Key results Photosynthetic pigments, antioxidant enzyme activities, dry matter yield and metal concentration in tissues were significantly influenced by ZnO NPs and Cd. Considered on its own as a main effect, Zn application (16 μM) enhanced its accumulation in roots, stem and leaf by about 33-fold (314 mg kg−1), 10-fold (60.6 mg kg−1) and 17-fold (110.8 mg kg−1), respectively, compared to control. However, accumulation was slower for interactions with Cd. While leaf Zn increased approximately 27 times (180 mg kg−1) at 32 μM Zn, its intera...
Organically modified clays have attracted increasing research attention for their various commerc... more Organically modified clays have attracted increasing research attention for their various commercial and industrial applications, such as being carriers for pesticide delivery. Besides, the suitability and performance of commercially available organoclays could further promote their applicability. Hence, this study investigated the potential application of a commercially available alkylamine-modified montmorillonite (MMT) nanoclay as a carrier for a widely used insecticide, imidacloprid. X-ray diffraction and thermogravimetric analysis were employed to illustrate the arrangement, orientation, and conformation of surfacemodifying agents (SMAs) on MMT nanoclay. It was observed that the clay was modified at an ∼1.0 cation exchange capacity, with the SMAs, especially octadecylamine, arranged in the MMT nanoclay as a bilayer to a pseudo-trilayer or a paraffin monolayer with a tilting angle of ∼25°, which indicated the nanoclay's ability to adsorb a large amount of imidacloprid. The adsorption−desorption of imidacloprid to MMT nanoclay further confirmed this applicability. A high adsorption capacity (∼85 mg g −1) was observed, with a high reversibility in desorption, showing a hysteresis value of 0.75. Further, the adsorption kinetics and response of the nanoclay to imidacloprid revealed that, initially, a rapid sorption occurred due to a hydrophobic interaction. This was followed by a slower diffusion-controlled sorption due to hydrogen bonding to the internal binding sites. The releasing pattern of imidacloprid from the MMT nanoclay indicated its potential for the preparation of a slow-releasing pesticide formulation where the nanoclay will reduce the instantaneous release of the total amount of pesticide.
Behaviour of heavy metals and their management to remediate and avoid agricultural soil contamina... more Behaviour of heavy metals and their management to remediate and avoid agricultural soil contamination
Zhaomin Dong, CuiXia Liu, Yanju Liu, Kaihong Yan, Kirk T. Semple and Ravi Naidu* 4 5 a Global Cen... more Zhaomin Dong, CuiXia Liu, Yanju Liu, Kaihong Yan, Kirk T. Semple and Ravi Naidu* 4 5 a Global Centre for Environmental Remediation, the Faculty of Science and Information Technology, 6 University of Newcastle, University Drive, Callaghan, NSW 2308, Australia 7 b Cooperative Research Centre for Contamination Assessment and Remediation of the Environment 8 (CRC CARE), Mawson Lakes, SA 5095, Australia 9 c School of Environmental Science and Engineering, Huazhong University of Science and Technology, 10 Wuhan 430074, China 11 d Lancaster Environment Centre, Lancaster University, LA1 4YQ Lancaster, United Kingdom 12 13 * Corresponding Author: Ravi Naidu 14 15 ATC Building, Global Center for Environmental Remediation, Faculty of Science and Information 16 Technology, University of Newcastle, Callaghan, NSW 2308 17
Nutrient pollution of surface water, such as excess phosphate loading on lake surface water, is a... more Nutrient pollution of surface water, such as excess phosphate loading on lake surface water, is a significant issue that causes ecological and financial damage. Despite many technologies that can remove available phosphate, such as material-based adsorption of those available phosphate ions, the development of a material that can trap them from the surface water is worth doing, considering other aspects. These aspects are: (i) efficient adsorption by the material while it settles down to the water column, and (ii) the material itself is not toxic to the lake natural microorganism. Considering these aspects, we developed a trace lanthanum-grafted surface-modified palygorskite, a fibrous clay mineral. It adsorbed a realistic amount of phosphate from the lake water (typically 0.13–0.22 mg/L). The raw and modified palygorskite (Pal) includes unmodified Australian Pal, heated (at ~400 °C) Pal, and acid (with 3 M HCl)-treated Pal. Among them, while acid-treated Pal grafted a lower amount ...
Environmental Science and Pollution Research, 2020
The levels of trace elements (As, Hg, Cr, Cd, Pb, Co, Ni, Cu, Mn and Zn) in commercially importan... more The levels of trace elements (As, Hg, Cr, Cd, Pb, Co, Ni, Cu, Mn and Zn) in commercially important fish species sampled from fish markets of Adelaide, Australia; canned fish from South Australian supermarkets; and fish markets of West Bengal, India were determined by inductively coupled plasma mass spectrometry (ICP-MS) after microwave digestion. Mercury was determined by using triple quadrupole ICP-MS. The accuracy of the methods was assessed with a certified standard reference material (NRCC-DORM-3 dogfish protein), and the results were compared with values reported in the literature. The results indicated considerable variations in the accumulation of trace elements among the fish species. The relationship between species with respect to trace element concentrations was examined using cluster analysis, which showed Indian fish species forming distinct groups from the others. Other than As in sardines, whiting and snapper and Hg in swordfish and snapper, the trace element concentrations were within permissible limits recommended by various standards. Based on the estimated daily intake (EDI), fish samples analysed in this study can be considered safe for human consumption as per the recommended daily dietary allowance limit fixed by various agencies. Continuous monitoring and assessments of fish metal(loid) content are needed to generate more data and safeguard human health.
The fate and behaviour of polycyclic aromatic hydrocarbons (PAHs) in soil is of interest in the r... more The fate and behaviour of polycyclic aromatic hydrocarbons (PAHs) in soil is of interest in the risk assessment of contaminated lands and are usually based on determinations of fractions extracted from soil. For decades, either single or sequential solvent extractions have been used to determine PAH extractability in soils; however, there is a lack of certainty as to which fractions are being extracted by these techniques. This study is the first report of changes and similarities in extractability of benzo[a]pyrene (B[a]P) in four contrasting soils (sandy loam, loamy sand, clayey loam, and sandy) when determined, simultaneously using both single (dichloromethane-DCM/acetone-Ace mixture) and sequential solvent (butanol followed by DCM/Ace) extractions. Residues after extraction were subjected to methanolic saponification (MeKOH). Butanol (BuOH)-and total-extractability of B[a]P, following sequential solvent extraction, decreased significantly (p < 0.05) with time after addition of B[a]P. The decrease in BuOH extractability was particularly marked in the organic matter-rich clayey loam soil which also had the largest (> 40%) amounts of non-extractable residues. The cumulative amounts of B[a]P extracted in each soil by single and sequential solvent extractions were similar (p > 0.05) at each aging period, which indicate access to similar B[a]P fractions in soil by both solvent extractions. The similarity in the amounts of B[a]P non-extractable residues recovered by MeKOH of pre-extracted soils, through either of the extraction methods, confirms that the total-extractable B[a]P fractions from both methods are similar.
Total and inorganic arsenic (As) content in rice and rice-based diets (n=59) obtained from superm... more Total and inorganic arsenic (As) content in rice and rice-based diets (n=59) obtained from supermarkets in South Australia were studied to investigate the contamination levels and whether consumption of these products pose potential health risks to young children and adults. Results show that of the 59 rice-based products, 31 (53 %) exceeded the EU recommended value (100 µg/kg) of As for young children and 13 (22%) samples had higher than maximum level of 200 µg/kg recommended for adults. Arsenic content varies as rice crackers > baby rice > rice cakes >puffed rice > other rice-based snacks > ready-to-eat rice. Of the 6 categories of ACCEPTED MANUSCRIPT rice-based products, except ready-to-eat rice, all others exceeded the EU recommended value for young children. Even manufacture recommended servings deliver significant amounts (0.56 to 6.87 µg) of inorganic As. These amounts are within the range of BMDL 01 values indicated by the European Food Safety Authority (EFSA), which means the risk cannot be avoided for young children and adults considering the levels of total and inorganic As in ricebased products.
Purpose A risk-based approach commonly applied for Pbcontaminated soil is stabilisation by phosph... more Purpose A risk-based approach commonly applied for Pbcontaminated soil is stabilisation by phosphate amendment. However, the proportion of Pb present in a form that is readily immobilised by phosphate addition is often limited. Chelates were examined as a means to mobilise Pb prior to immobilisation to increase the proportion of Pb that could react with phosphate. Four contrasting shooting range soils from around Australia (Murray Bridge (MB), Townsville (TV), Darwin (DA) and Perth (PE)) were used for the study. Materials and methods Chelating agents such as ethylenediaminetetraacetic acid (EDTA) are able to extract Pb from existing species in the soil, forming complexes. By lowering soil pH or adding Fe 3+ for the displacement of Pb from the complex, a greater proportion of Pb may be available for reaction with phosphate. The use of biodegradable ethylenediamine-N,N′-disuccinic acid (EDDS) minimises residual effects of chelate treatment in the soil. Results and discussion EDTA was not found to be suitable due to the stability of the chelate-Pb complex. The addition of EDDS had variable effect between the four shooting range soils. In the strongly weathered oxidic TV and DA soils, applying EDDS prior to phosphate amendment produced greater reduction in bioaccessible Pb, but in the less weathered MB and PE soil, bioaccessible Pb was increased. Water-extractable (WE) Pb increased in the soils by EDDS application, but this could be offset by lime application in DA soil, without negatively affecting Pb bioaccessibility; WE Pb also decreased over time when ammonium nitrate was added to the soil. Conclusions Application of EDDS may be able to increase the proportion of Pb that reacts with phosphate in the soil, providing greater reduction in bioaccessible Pb than phosphate-only treatments. Additional treatability studies are needed to test amendments that could manage the water-extractable portion of Pb and to optimise application of EDDS for the best outcome.
Activated biocarbons with a porous structure and nitrogen functionalities are synthesized from th... more Activated biocarbons with a porous structure and nitrogen functionalities are synthesized from the prolific waste biomass, Arundo donax, and an organic material, chitosan, by a simple one step chemical activation with ZnCl2.
Journal of colloid and interface science, Jan 15, 2014
Kaolinite supported bimetallic Fe/Ni nanoparticles (K-Fe/Ni) demonstrated capacity for simultaneo... more Kaolinite supported bimetallic Fe/Ni nanoparticles (K-Fe/Ni) demonstrated capacity for simultaneous removal of both cationic and anionic contaminants such as Pb (II) and NO3(-). The dispersion of Fe/Ni nanoparticles was improved when kaolinite was used as a stabilizer, and also enhanced the reactivity of K-Fe/Ni. The adsorption of Pb (II) onto the kaolinite and the consequent simultaneous catalytic reduction of Pb (II) and NO3(-) kaolinite were confirmed by SEM, BET, EDS, XRD and batch adsorption-reduction test. Orthogonal method showed that initial concentrations of Pb (II) and NO3(-), as well the dosage of K-Fe/Ni showed the most significant impact on the removal rates, where 86.3% of Pb (II) and 73.6% of NO3(-) was removed at optimized conditions. In addition, K-Fe/Ni could be stored for 15 days in dry air without losing reactivity. Reusability test of K-Fe/Ni indicated that the removal efficiency decreased by 12.5% for Pb (II) and 27.2% for NO3(-) after using 3 times successivel...
The degradation of naphthalene using immobilized Bacillus fusiformis (BFN) strain on alginate-pol... more The degradation of naphthalene using immobilized Bacillus fusiformis (BFN) strain on alginate-polyvinyl alcohol (PVA)-clays bead was much higher than that of using a freely suspended BFN strain. This was due to the beads facilitating biodegradation by enhancing concentration of naphthalene using the beads as an adsorbent in the cells' vicinity. This was confirmed by the kinetics of naphthalene on the beads, where its adsorption onto the beads was confirmed by pseudo-second-order kinetics. The biodegradation of naphthalene fitted well to the first-order rate model. More than 99.7% of naphthalene which was removed within 12 h, contained bentonite 2% (w/v), PVA 12% (w/v), alginate 0.3% (w/v) and 10% (v/v) initial biomass loading. Scanning electron microscopy (SEM) of the beads showed that Bacillus fusiformis was evenly distributed within them. Storage stability and reusability results revealed that the ability to degrade naphthalene using beads with immobilized cells remained stable after storage at 4 0 C for 35 days and being reused 8 times (12 days), respectively. Furthermore the naphthalene degradation rate of immobilized cells was maintained (94.3%) at the eighth cycle.
Journal of agricultural and food chemistry, Jan 25, 2014
Rice is an important route of arsenic (As) exposure to humans, especially populations with rice-b... more Rice is an important route of arsenic (As) exposure to humans, especially populations with rice-based diets. Human health risk of As varies greatly with rice variety and country of origin. The purpose of the present study was to determine total and speciated As in Australian-grown and imported rice on sale in Australia to assess their health risk to consumers. The total As (tAs) concentrations in Australian-grown organic brown, medium grain brown, and organic white rice were 438±23, 287±03, and 283±18 μg kg(-1) dry weight (d wt), respectively. In Bangladeshi, Indian, Pakistani, and Thai rice imported and on sale in Australia, tAs concentrations were 56±05, 92±10, 82±06 and 172±24 μg kg(-1), respectively. Asian rice contained mainly inorganic As (iAs; 86-99%), whereas 18-26% of the tAs in Australian-grown rice was dimethylarsinic acid (DMA). Relatively higher concentrations of tAs in Australian-grown rice than that in imported rice of Asian origin suggest that Australian-grown rice m...
ABSTRACT This work evaluated surfactant-enhanced in situ chemical oxidation (S-ISCO) in a hydroca... more ABSTRACT This work evaluated surfactant-enhanced in situ chemical oxidation (S-ISCO) in a hydrocarbon-contaminated soil. Surfactants and efficacy of oxidant activation as well as the treatability of contaminated soil were assessed. The surfactant VeruSOL-3 with a critical micelle concentration (CMC) of 5.5 g/L was selected. Based on the results, activated oxidations by sodium persulphate and hydrogen peroxide were able to effectively destroy target organic compounds in emulsion and soil. The destruction of total petroleum hydrocarbon (TPH) in emulsion was completed in 14 days and polycyclic aromatic hydrocarbons (PAHs) in excess of 96 %. Green nanoiron was much more active than other activators in emulsion. The data also indicates that oxidation using activators was much less pronounced in soil matrices. However, it is expected that given sufficient dose and treatment time, a higher destruction rate in the contaminated soil can be achieved. The study showed that the remediation of target organic contaminants (TPH, PAH) in soil by S-ISCO using activated sodium persulphate is feasible.
Journal of Liquid Chromatography & Related Technologies, 2003
... via control of the BGE pH to obtain reasonable selectivity.1–3 View all references Organic mo... more ... via control of the BGE pH to obtain reasonable selectivity.1–3 View all references Organic modifiers, such as organic solvents and large hydrophobic cations, can also alter the EOF by altering the charge density at the surface of the fused‐silica capillary.[4]4. Sarmini, K. and ...
Indirect UV detection in capillary zone electrophoresis (CZE) is frequently used for the determin... more Indirect UV detection in capillary zone electrophoresis (CZE) is frequently used for the determination of inorganic anions and carboxylic acids. However, there are few reports on direct UV detection of these solutes in real samples. This paper describes the use of direct UV detection of inorganic anions and organic acids in environmental samples using co-electroosmotic capillary zone electrophoresis (co-CZE) at 185 nm. The best separation and detection of the solutes was achieved using a fused silica capillarywith an electrolyte containing 25 mM phosphate, 0.5 mM tetradecyltrimethylammonium bromide (gAB) and 15% acetonitrile (v/v) at pH 6.0. Four common inorganic anions (CI-, NO2-, NO3-and SO42-) and 11 organic acids (oxalic, formic, fumaric, tartaric, malonic, malic, citric, succinic, maleic, acetic, and lactic acid), were determined simultaneously in 15 min. Linear calibration plots for the test solutes were obtained in the range 0.02-0.5 mM with detection limits ranging from 1-9 I~M depending on the analyte. The proposed method was successfully used to determine inorganic anions and carboxylic acids in soil and plant tissue extracts with direct injection of the sample.
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