Browsing by Author "Bennett, WW"

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    Fate and sublethal effects of metals during amphibian metamorphosis: a systematic review
    (Taylor & Francis, 2021-11-11) Hill, D; Cresswell, T; Bennett, WW; Lanctôt, CM
    Amphibians provide essential ecosystem services and are facing global decline. Exposure to contaminants is a contributing factor to this decline, with permeable skin and early aquatic life likely increasing amphibian susceptibility. Their vulnerability may also be increased through metamorphosis, which involves degeneration of tissues and high energy expenditure. Exposure to metal contaminants may also result in delays to metamorphosis or reduced growth. Understanding how metal burdens change during metamorphosis and the effects metals have on postmetamorphic amphibians is essential to ensure water quality guidelines offer sufficient protection. A systematic review of the literature was conducted to identify the changes in whole-body metal burden and biodistribution pre and postmetamorphosis and the effects of metal exposures on the timing of metamorphosis and size of animals postmetamorphosis. Premetamorphic amphibians were found to have higher metal concentrations than postmetamorphic, suggesting these metals can be largely excreted prior to or during metamorphosis. Only two articles were identified that compared changes in metal biodistribution during metamorphosis, with both reporting decreasing concentrations in the gut from pre to postmetamorphosis. No laboratory studies identified significant effects relating to metamorphosis at concentrations below USEPA chronic water quality criteria. However, delays to timing or growth were observed in field studies where all analyzed metals were below criteria. Many articles did not meet the suggested minimum reporting standards, particularly for the reporting of metal exposure concentrations and physico-chemical conditions of exposure solutions. © 2021 Informa UK Limited
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    Metal forms and dynamics in urban stormwater runoff: new insights from diffusive gradients in thin-films (DGT) measurements
    (Elsevier, 2022-02-01) McDonald, S; Holland, A; Simpson, SL; Gadd, JB; Bennett, WW; Walker, GW; Keough, MJ; Cresswell, T; Hassell, KL
    Stormwater runoff typically contains significant quantities of metal contaminants that enter urban waterways over short durations and represent a potential risk to water quality. The origin of metals within the catchment and processes that occur over the storm can control the partitioning of metals between a range of different forms. Understanding the fraction of metals present in a form that is potentially bioavailable to aquatic organisms is useful for environmental risk assessment. To help provide this information, the forms and dynamics of metal contaminants in an urban system were assessed across a storm. Temporal patterns in the concentration of metals in dissolved and particulate (total suspended solids; TSS) forms were assessed from water samples, and diffusive gradients in thin-films (DGTs) were deployed to measure the DGT-labile time-integrated metal concentration. Results indicate that the concentrations of dissolved and TSS-associated metals increased during the storm, with the metals Al, Cd, Co, Cu, Pb and Zn representing the greatest concern relative to water quality guideline values (GVs). The portion of labile metal as measured by DGT devices indicated that during the storm a substantial fraction (∼98%) of metals were complexed and pose a lower risk of acute toxicity to aquatic organisms. Comparison of DGT results to GVs indicate that current GVs are likely quite conservative when assessing stormwater pollution risks with regards to metal contaminants. This study provides valuable insight into the forms and dynamics of metals in an urban system receiving stormwater inputs and assists with the development of improved approaches for the assessment of short-term, intermittent discharge events. © 2021 Elsevier Ltd.
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    Synchrotron-based imaging reveals the fate of selenium in striped marsh frog tadpoles
    (American Chemical Society, 2021-08-12) Lanctôt, CM; Cresswell, T; Lombi, E; Bennett, WW
    Synchrotron-based X-ray fluorescence microscopy (XFM) coupled with X-ray absorption near-edge structure (XANES) imaging was used to study selenium (Se) biodistribution and speciation in Limnodynastes peronii tadpoles. Tadpoles were exposed to dissolved Se (30 μg/L) as selenite (SeIV) or selenate (SeVI) for 7 days followed by 3 days of depuration. High-resolution elemental maps revealed that Se partitioned primarily in the eyes (specifically the eye lens, iris, and retinal pigmented epithelium), digestive and excretory organs of SeIV-exposed tadpoles. Speciation analysis confirmed that the majority of accumulated Se was converted to organo-Se. Multielement analyses provided new information on Se colocalization and its impact on trace element homeostasis. New insights into the fate of Se on a whole organism scale contribute to our understanding of the mechanisms and risks associated with Se pollution. © 2021 American Chemical Society