2024 |
Umeh AC, Naidu R, Olisa E, Liu Y, Qi F, Bekele D, 'A systematic investigation of single solute, binary and ternary PFAS transport in water-saturated soil using batch and 1-dimensional column studies: Focus on mixture effects.', Journal of hazardous materials, 461 132688 (2024) [C1]
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Nova |
2024 |
Bahar MM, Samarasinghe SVAC, Bekele D, Naidu R, 'Residual hydrocarbons in long-term contaminated soils: implications to risk-based management.', Environ Sci Pollut Res Int, (2024) [C1]
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2023 |
Unnithan A, Bekele D, Samarasinghe C, Chadalavada S, Naidu R, 'Evaluating the role of preferential pathways in exacerbating vapour intrusion risks', Journal of Hazardous Materials Advances, 10 100310-100310 (2023) [C1]
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Nova |
2023 |
Warner SD, Bekele D, Nathanail CP, Chadalavada S, Naidu R, 'Climate-influenced hydrobiogeochemistry and groundwater remedy design: A review', Remediation Journal, 33 187-207 (2023) [C1]
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Nova |
2023 |
Unnithan A, Bekele DN, Chadalavada S, Naidu R, 'Two-dimensional chlorinated vapour intrusion model involving advective transport of vapours with a highly permeable granular layer in the vadose zone serving as the preferential pathway.', Sci Total Environ, 869 161743 (2023) [C1]
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Nova |
2021 |
Wang L, Cheng Y, Naidu R, Chadalavada S, Bekele D, Gell P, et al., 'Application of portable gas chromatography mass spectrometer for rapid field based determination of TCE in soil vapour and groundwater', Environmental Technology and Innovation, 21 (2021) [C1]
The application of portable chromatography¿mass spectrometer (GC¿MS) is restrained by its detection limits without the development of proper sample pre-concentration methods. The ... [more]
The application of portable chromatography¿mass spectrometer (GC¿MS) is restrained by its detection limits without the development of proper sample pre-concentration methods. The primary focus of this paper is to introduce a practical field measurement methodology for the analysis of volatile organic compounds (VOCs) in soil vapour and groundwater using a portable gas (GC¿MS)system for application to in situ assessment of vapour intrusion from VOC contamination. A solid-phase micro-extraction (SPME) technique was applied for sample pre-concentration before the GC¿MS¿ measurement. Practical in-field soil gas SPME sampling methods have been developed to optimise the SPME extraction efficiency to then ultimately improve the detection limits of portable GC¿MS. An Australian site impacted by a chlorinated VOC, trichloroethylene (TCE), was the subject of the case study. To rapidly assess soil vapour samples in subsurface soil, in-house-developed retractable soil vapour sampling probes (SVSPs) were installed at the site in clusters at depths of 1 m, 2 m and 3 m below ground level at each sampling location. Use of the SVSPs for sampling enabled the generation of a three-dimensional map and distribution contours for TCE concentrations using the in situ measurement results of a portable GC¿MS analysis for vapour intrusion investigation. The results of the portable GC¿MS¿ analysis were compared with the results from conventional USEPA methods, such as TO-15 and Method 8265 for soil vapour and groundwater samples, respectively. This work demonstrates that the developed methodology of using a portable GC¿MS system has the capability for in-field quantitative analysis of VOCs for rapid contaminated site vapour intrusion assessment.
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Nova |
2021 |
Molla AS, Tang P, Sher W, Bekele DN, 'Chemicals of concern in construction and demolition waste fine residues: A systematic literature review', Journal of Environmental Management, 299 (2021) [C1]
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Nova |
2021 |
Unnithan A, Bekele DN, Chadalavada S, Naidu R, 'Insights into vapour intrusion phenomena: Current outlook and preferential pathway scenario', Science of the Total Environment, 796 (2021) [C1]
Vapour intrusion (VI) is the phenomenon by which volatile organic compounds (VOCs) migrate from the subsurface source through the soil and enter into the overlying buildings, affe... [more]
Vapour intrusion (VI) is the phenomenon by which volatile organic compounds (VOCs) migrate from the subsurface source through the soil and enter into the overlying buildings, affecting the indoor air quality and ultimately causing health hazards to the occupants. Health risk assessments associated with hydrocarbon contaminated sites and recommendations of site closure are often made by quantifying the VI risks using mathematical models known as ¿vapour intrusion models¿ (VIM). In order to predict the health risk, various factors such as the lithological and geochemical conditions of the subsurface, environmental conditions, building operational conditions etc. are commonly evaluated using VIMs. Use of these models can overlook the role of preferential pathways like highly permeable subsurface layers and utility lines which act as the path of least resistance for vapour transport, which can increase the VI risks. The extensive networks of utility lines and sanitary sewer systems in urban areas can significantly exacerbate the uncertainty of VI investigations. The backfill materials like sand and gravel surrounding the utility lines can allow the vapours to easily pass through due to their high porosity as compared to natural formations. Hence, failure to understand the role of preferential pathways on the fate and transport of VOC in the vadose zone can result in more conservative predictions of indoor air vapour concentrations and wrong clean up approaches. This comprehensive review outlines the vapour transport mechanisms, factors influencing VI, VIMs and the role of preferential pathways in predicting indoor air vapour concentrations.
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Nova |
2021 |
Saini A, Bekele DN, Chadalavada S, Fang C, Naidu R, 'Electrokinetic remediation of petroleum hydrocarbon contaminated soil (I)', Environmental Technology and Innovation, 23 (2021) [C1]
The remediation of petroleum hydrocarbons (TPH) in a contaminated soil by electrokinetic (EK) treatment was studied in the laboratory. The effects of applying a constant electrica... [more]
The remediation of petroleum hydrocarbons (TPH) in a contaminated soil by electrokinetic (EK) treatment was studied in the laboratory. The effects of applying a constant electrical current on soil pH, moisture content, electrical conductivity (EC), temperature, and the concentrations of three fractions of TPH (C10¿C16, C17¿C34 and C35¿C40) were investigated. The experiment was run for seven days and soil samples were collected at the end of the 7 day period for analysis of soil pH and TPH concentration. There were extreme pH conditions near the electrodes. At the end of the experiment there was around a 37% reduction of C10¿C16 chain compounds compared to the initial concentration of 164 ± 18 mg/kg. The study investigated TPH remediation to a depth of 24 cm, which is significantly more than most studies of EK remediation of TPH-contaminated soils. We observed reductions in TPH concentrations even at a depth of 24 cm. The spatial distribution of reductions in TPH concentrations was also studied and it was observed that more remediation occurred near the cathodes than near the anodes. Further, the greatest reductions in TPH concentrations were recorded near the electrodes in the lowest and middle parts of the experimental set-up. The application of electrokinetics to remediate TPH-contaminatedsoils could be a viable option as an in situ remediation technology.
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Nova |
2020 |
Besha AT, Liu Y, Fang C, Bekele DN, Naidu R, 'Assessing the interactions between micropollutants and nanoparticles in engineered and natural aquatic environments', Critical Reviews in Environmental Science and Technology, 50 135-215 (2020) [C1]
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Nova |
2020 |
Saini A, Bekele DN, Chadalavada S, Fang C, Naidu R, 'A review of electrokinetically enhanced bioremediation technologies for PHs', Journal of Environmental Sciences, 88 31-45 (2020) [C1]
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Nova |
2020 |
Naidu R, Nadebaum P, Fang C, Cousins I, Pennell K, Conder J, et al., 'Per- and poly-fluoroalkyl substances (PFAS): Current status and research needs', Environmental Technology and Innovation, 19 (2020) [C1]
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Nova |
2020 |
Hepburn E, Cendón DI, Bekele D, Currell M, 'Environmental isotopes as indicators of groundwater recharge, residence times and salinity in a coastal urban redevelopment precinct in Australia', Hydrogeology Journal, 28 503-520 (2020) [C1]
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Nova |
2020 |
Bekele DN, Liu Y, Donaghey M, Umeh A, Arachchige CSV, Chadalavada S, Naidu R, 'Separation and Lithological Mapping of PFAS Mixtures in the Vadose Zone at a Contaminated Site', Frontiers in Water, 2 [C1]
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Nova |
2020 |
Besha AT, Liu Y, Bekele DN, Dong Z, Naidu R, Gebremariam GN, 'Sustainability and environmental ethics for the application of engineered nanoparticles', ENVIRONMENTAL SCIENCE & POLICY, 103 85-98 (2020) [C1]
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Nova |
2019 |
Hepburn E, Northway A, Bekele D, Currell M, 'A framework and simple decision support tool for groundwater contamination assessment in an urban redevelopment precinct', Hydrogeology Journal, 27 1911-1928 (2019) [C1]
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Nova |
2019 |
Gebremariam MG, Zhu Y, Ahmad N, Bekele DN, 'Influencing sustainability by controlling future brownfields in Africa: a case study of Ethiopia', WORLD JOURNAL OF SCIENCE TECHNOLOGY AND SUSTAINABLE DEVELOPMENT, 16 102-120 (2019) [C1]
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Nova |
2019 |
Bekele DN, Du J, de Freitas LG, Mallavarapu M, Chadalavada S, Naidu R, 'Actively facilitated permeable reactive barrier for remediation of TCE from a low permeability aquifer: Field application', Journal of Hydrology, 572 592-602 (2019) [C1]
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Nova |
2019 |
Hepburn E, Northway A, Bekele D, Currell M, 'Incorporating perfluoroalkyl acids (PFAA) into a geochemical index for improved delineation of legacy landfill impacts on groundwater', Science of the Total Environment, 666 1198-1208 (2019) [C1]
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Nova |
2019 |
Alemayehu T, Mebrahtu G, Hadera A, Bekele DN, 'Assessment of the impact of landfill leachate on groundwater and surrounding surface water: a case study of Mekelle city, Northern Ethiopia', Sustainable Water Resources Management, 5 1641-1649 (2019) [C1]
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Nova |
2018 |
Bekele DN, Naidu R, Chadalavada S, 'Development of a modular vapor intrusion model with variably saturated and non-isothermal vadose zone', Environmental Geochemistry and Health, 40 887-902 (2018) [C1]
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Nova |
2018 |
Besha AT, Bekele DN, Naidu R, Chadalavada S, 'Recent advances in surfactant-enhanced In-Situ Chemical Oxidation for the remediation of non-aqueous phase liquid contaminated soils and aquifers', Environmental Technology and Innovation, 9 303-322 (2018) [C1]
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Nova |
2018 |
Hepburn E, Northway A, Bekele D, Liu G-J, Currell M, 'A method for separation of heavy metal sources in urban groundwater using multiple lines of evidence.', Environmental Pollution, 241 787-799 (2018) [C1]
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Nova |
2017 |
Besha AT, Gebreyohannes AY, Tufa RA, Bekele DN, Curcio E, Giorno L, 'Removal of emerging micropollutants by activated sludge process and membrane bioreactors and the effects of micropollutants on membrane fouling: A review', Journal of Environmental Chemical Engineering, 5 2395-2414 (2017) [C1]
Recently, emerging contaminants such as micropollutants presence in water poses significant challenge to regulators, engineers and scientific community. Micropollutants are introd... [more]
Recently, emerging contaminants such as micropollutants presence in water poses significant challenge to regulators, engineers and scientific community. Micropollutants are introduced in the aquatic environment primarily from discharge of treated effluent from wastewater treatment plants (WWTP). Advanced treatment processes: reverse osmosis, and membrane bioreactor (MBR) can achieve higher and more consistent micropollutants removal. Despite the used technology, the removal of micropollutants depends on phsyico-chemical properties of micropollutants and the treatment conditions. Several advantages make MBR to be recognized as the next generation for wastewater treatment. However, its efficiency is limited due to the presence of micropollutants, causing peculiar membrane fouling. This review compares MBR and conventional activated sludge (CAS) for wastewater treatment and discusses problems arising from the presence of emerging micropollutants, such as the low removal efficiency for certain types of compounds. Mechanisms of micropollutants removal are summarized and related to MBRs operational conditions based on the vast literature existing in this topic. Adsorption and subsequent biodegradation of the micropollutants have been identified as the dominant removal processes, and they are influenced by operational conditions such as solid retention time, biomass concentration, temperature, redox conditions and pH. The review also provides a detailed overview of the effects of micropollutants on microbial activities, since microorganisms respond to environmental stress by producing different polysaccharides and proteins that have a direct impact on membrane fouling. Finally, pertinent issues that must be addressed in order to increase the market share of MBR in the removal of emerging micropollutants are highlighted.
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Nova |
2016 |
Bekele DN, Naidu R, Chadalavada S, 'Influence of soil properties on vapor-phase sorption of trichloroethylene', Journal of Hazardous Materials, 306 34-40 (2016) [C1]
Current practices in health risk assessment from vapor intrusion (VI) using mathematical models are based on assumptions that the subsurface sorption equilibrium is attained. The ... [more]
Current practices in health risk assessment from vapor intrusion (VI) using mathematical models are based on assumptions that the subsurface sorption equilibrium is attained. The time required for sorption to reach near-steady-state conditions at sites may take months or years to achieve. This study investigated the vapor phase attenuation of trichloroethylene (TCE) in five soils varying widely in clay and organic matter content using repacked columns. The primary indicators of TCE sorption were vapor retardation rate (Rt), the time required for the TCE vapor to pass through the soil column, and specific volume of retention (VR), and total volume of TCE retained in soil. Results show TCE vapor retardation is mainly due to the rapid partitioning of the compound to SOM. However, the specific volume of retention of clayey soils with secondary mineral particles was higher. Linear regression analyses of the SOM and clay fraction with VR show that a unit increase in clay fraction results in higher sorption of TCE (VR) than the SOM. However, partitioning of TCE vapor was not consistent with the samples' surface areas but was mainly a function of the type of secondary minerals present in soils.
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Nova |
2015 |
Dong Z, Liu Y, Duan L, Bekele D, Naidu R, 'Uncertainties in human health risk assessment of environmental contaminants: A review and perspective', Environment International, 85 120-132 (2015) [C1]
Addressing uncertainties in human health risk assessment is a critical issue when evaluating the effects of contaminants on public health. A range of uncertainties exist through t... [more]
Addressing uncertainties in human health risk assessment is a critical issue when evaluating the effects of contaminants on public health. A range of uncertainties exist through the source-to-outcome continuum, including exposure assessment, hazard and risk characterisation. While various strategies have been applied to characterising uncertainty, classical approaches largely rely on how to maximise the available resources. Expert judgement, defaults and tools for characterising quantitative uncertainty attempt to fill the gap between data and regulation requirements. The experiences of researching 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) illustrated uncertainty sources and how to maximise available information to determine uncertainties, and thereby provide an 'adequate' protection to contaminant exposure. As regulatory requirements and recurring issues increase, the assessment of complex scenarios involving a large number of chemicals requires more sophisticated tools. Recent advances in exposure and toxicology science provide a large data set for environmental contaminants and public health. In particular, biomonitoring information, in vitro data streams and computational toxicology are the crucial factors in the NexGen risk assessment, as well as uncertainties minimisation. Although in this review we cannot yet predict how the exposure science and modern toxicology will develop in the long-term, current techniques from emerging science can be integrated to improve decision-making.
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Nova |
2015 |
Wang L, Liu E, Cheng Y, Bekele DN, Lamb D, Chen Z, et al., 'Novel methodologies for automatically and simultaneously determining BTEX components using FTIR spectra', Talanta, 144 1104-1110 (2015) [C1]
This study introduced a patented novel methodological system for automatically analysis of Fourier Transform Infrared Spectrometer (FTIR) spectrum data located at 'fingerprin... [more]
This study introduced a patented novel methodological system for automatically analysis of Fourier Transform Infrared Spectrometer (FTIR) spectrum data located at 'fingerprint' region (wavenumber 670-800 cm-1), to simultaneously determinate multiple petroleum hydrocarbons (PHs) in real mixture samples. This system includes: an object oriented baseline correction; Band decomposition (curve fitting) method with mathematical optimization; and Artificial Neural Network (ANN) for determination, which is suitable for the characteristics of this IR regions, where the spectra are normally with low signal to noise ratio and high density of peaks. BTEX components are potentially lethal carcinogens and contained in many petroleum products. As a case study, six BTEX components were determinate automatically and simultaneously in mixture vapor samples. The robustness of the BTEX determination was validated using real petroleum samples, and the prediction results were compared with gas chromatography-mass spectrometry (GC-MS).
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Nova |
2014 |
Bekele DN, Naidu R, Chadalavada S, 'Influence of spatial and temporal variability of subsurface soil moisture and temperature on vapour intrusion', Atmospheric Environment, 88 14-22 (2014) [C1]
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2013 |
Bekele DN, Naidu R, Bowman M, Chadalavada S, 'Vapor Intrusion Models for Petroleum and Chlorinated Volatile Organic Compounds: Opportunities for Future Improvements', VADOSE ZONE JOURNAL, 12 (2013) [C1]
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