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Li Y.,University of New South Wales | Low G.K.-C.,Environmental Forensic and Analytical Science | Scott J.A.,University of New South Wales | Amal R.,University of New South Wales
Chemosphere | Year: 2010

Arsenic species in municipal landfill leachates (MLL) were investigated by HPLC-DRC-ICPMS and LC-ESI-MS/MS. Various arsenic species including arsenate (iAsV), arsenite (iAsIII), monomethylarsonic acid (MMAV), dimethylarsinic acid (DMAV), as well as sulfur-containing organoarsenic species were detected. Two sulfur-containing arsenic species in a MLL were positively identified as dimethyldithioarsinic acid (DMDTAV) and dimethylmonothioarsinic acid (DMMTAV) by comparing their molecular ions, fragment patterns and sulfur/arsenic ratios with in-house synthesised thiol-organoarsenic compounds. The findings demonstrated the potential for transformation of DMAV to DMDTAV and DMMTAV in a DMAV-spiked MLL in a landfill leachate environment. © 2010 Elsevier Ltd. Source

Li Y.,University of New South Wales | Low G.K.-C.,Environmental Forensic and Analytical Science | Scott J.A.,University of New South Wales | Amal R.,University of New South Wales
Journal of Hazardous Materials | Year: 2011

The microbial transformation of arsenic species in municipal landfill leachate (MLL) was investigated with the objective to highlight arsenic transformation in the landfill system. Across the 43 day incubation in MLL, more than 90% arsenate (iAsV) was found to reduce to arsenite (iAsIII) within 20 days, while iAsIII was comparably stable although a fraction of iAsIII was temporarily oxidated to iAsV in the first 3 days. Transformation of monomethylarsonic acid (MMAV) to dimethylarsinic acid (DMAV) in MLL was slow with only 5% MMAV methylated to DMAV after 43 days incubation. A portion of DMAV and MMAV in MLL was demonstrated to transform into thiol-organoarsenic and monomethylarsonous acid (MMAIII), which were identified to include dimethyldithioarsinic acid (DMDTAV), dimethylmonothioarsinic acid (DMMTAV) and monomethyldithioarsonic acid (MMDTAV) by HPLC-ICPMS and LC-ESI-MS/MS. The microbial formation of DMDTAV, DMMTAV and MMDTAV is postulated to relate to hydrogen sulfide generated by bacteria in MLL. Differences in arsenic transformation in sterilised and non-sterilised MLLs demonstrate bacteria play a crucial role in arsenic transformation in the landfill body. This study reveals the complexity of arsenic speciation and highlights the potential risk of forming highly toxic thiol-organoarsenic and MMAIII in the landfill environment. © 2011 Elsevier B.V. Source

Fuller S.,Environmental Forensic and Analytical Science | Spikmans V.,University of Western Sydney | Vaughan G.,Environmental Forensic and Analytical Science | Guo C.,Envirolab Services
Environmental Forensics | Year: 2013

The weathering of biodiesel and biodiesel/diesel blends was investigated to determine the changes in the profiles of fatty acid methyl esters (FAMEs), sterols, and hydrocarbons. Sterols were more persistent than FAMEs and are better candidates for identifying biodiesels in environmental media and for determining the source of a biodiesel spill. The changes in FAME and sterol profiles over time are discussed. In biodiesel blends, accelerated weathering was observed for pyrene, fluoranthene, and their alkyl homologues compared to diesel. FAME and sterol analysis should be performed in addition to hydrocarbon profiling to distinguish between a weathered diesel and a weathered biodiesel/diesel blend. © 2013 Copyright Taylor and Francis Group, LLC. Source

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