Browsing by Author "Hassell, KL"

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    Bioaccumulation kinetics of cadmium and zinc in the freshwater decapod crustacean Paratya australiensis following multiple pulse exposures
    (Elsevier, 2020-06-10) McDonald, S; Cresswell, T; Hassell, KL
    Stormwater runoff has been identified as a major source of metal contaminants in urban waterways, where during storm events organisms tend to be exposed to short-term pulses, rather than a constant exposure of contaminants. Current water quality guidelines (WQGs) are generally derived using data from continuous exposure toxicity tests, where there is an assumption that chronic exposures provide a meaningful way of assessing the impacts and effects in organisms as a result of these pulsed storm events. In this current study the radioisotopes 109Cd and 65Zn were used to explore uptake, depuration and organ distribution in the decapod crustacean Paratya australiensis, over three short-term (<10 h) exposures. Exposures to radiolabelled cadmium only, zinc only or a mixture of cadmium and zinc were followed by depuration in metal- and isotope-free water for 7 days. Whole-body metal concentrations were determined by live-animal gamma-spectrometry and an anatomical distribution of the radioisotopes was visualised using autoradiography post-mortem. Both metals were significantly accumulated over the pulsed exposure period. In both treatments cadmium and zinc body burden increased at the same rate over the three pulses. Final metal body burden did not markedly differ when shrimp were exposed to metals individually compared to a binary mixture. Over the course of the depuration period, cadmium efflux was minimal, whereas zinc efflux was significant. Autoradiography indicated the presence of both metals in the gills and hepatopancreas throughout the depuration period. These results demonstrate how short-term repeated exposures result in the accumulation of contaminants by shrimp. This study highlights the importance of considering the inclusion of pulsed toxicity tests in frameworks when deriving WQGs. © 2020 Elsevier B.V
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    Dietary uptake and depuration kinetics of perfluorooctane sulfonate, perfluorooctanoic acid, and hexafluoropropylene oxide dimer acid (GenX) in a benthic fish
    (John Wiley & Sons, Inc, 2019-11-21) Hassell, KL; Coggan, TL; Cresswell, T; Kolobaric, A; Berry, K; Crosbie, ND; Blackbeard, J; Pettigrove, VJ; Clarke, BO
    Per- and poly-fluoroalkyl substances (PFAS) are ubiquitously distributed throughout aquatic environments and can bioaccumulate in organisms. We examined dietary uptake and depuration of a mixture of 3 PFAS: perfluorooctanoic acid (PFOA; C8HF15O2), perfluorooctane sulfonate (PFOS; C8HF17SO3), and hexafluoropropylene oxide dimer acid (HPFO-DA; C6HF11O3; trade name GenX). Benthic fish (blue spot gobies, Pseudogobius sp.) were fed contaminated food (nominal dose 500 ng g–1) daily for a 21-d uptake period, followed by a 42-d depuration period. The compounds PFOA, linear-PFOS (linear PFOS), and total PFOS (sum of linear and branched PFOS) were detected in freeze-dried fish, whereas GenX was not, indicating either a lack of uptake or rapid elimination (<24 h). Depuration rates (d–1) were 0.150 (PFOA), 0.045 (linear-PFOS), and 0.042 (linear+branched-PFOS) with corresponding biological half-lives of 5.9, 15, and 16 d, respectively. The PFOS isomers were eliminated differently, resulting in enrichment of linear-PFOS (70–90%) throughout the depuration period. The present study is the first reported study of GenX dietary bioaccumulation potential in fish, and the first dietary study to investigate uptake and depuration of multiple PFASs simultaneously, allowing us to determine that whereas PFOA and PFOS accumulated as expected, GenX, administered in the same way, did not appear to bioaccumulate. © 2019 SETAC
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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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    Metal pollution during pulse stormwater events: bioaccumulation kinetics of cadmium and zinc in a freshwater decapod crustacean
    (Australian Nuclear Science and Technology Organisation, 2019-09-03) McDonald, S; Cresswell, T; Hassell, KL
    Stormwater runoff has been identified as a major source of metal pollutants in urban waterways, where organisms that access these environments tend to be exposed to multiple pulses, rather than a constant exposure, of contaminants. Current water quality guidelines (WQGs) are generally derived using data from continuous exposure toxicity tests, where the assumption is that chronic exposures provide a meaningful way of assessing metal bioaccumulation kinetics and effects in an organism. In this study the radioisotopes 109Cd and 65Zn were used to explore the uptake, depuration and organ distribution of a non-essential and essential metal in a decapod crustacean over the course of three short-term (< 10 hours) pulse exposures followed by a 7-day depuration. The freshwater shrimp (Paratya australiensis) was exposed to radiolabelled cadmium only, zinc only and a mixture of cadmium and zinc at environmentally relevant stormwater concentrations. Whole-body metal concentrations were determined by daily live-animal gamma-spectrometry. Anatomical distribution of the radioisotopes was visualised using autoradiography at multiple time points throughout the depuration period. Metal uptake and efflux rates were similar in the individual and mixed-metal exposures, where both metals accumulated to a greater extent when presented individually. Interestingly, the rate of cadmium uptake in the whole-body of the organism over the course of the three ‘pulses’ decreased with each successive pulse. The rate of zinc uptake remained linear over the course of the three pulsed exposures. The efflux rate for cadmium regardless of exposure treatment (single or multi-metal) was close to zero. Zinc concentrations decreased in the whole-body of the organism over the course of the depuration period, with the efflux rate being greater for zinc exposed individually. Autoradiography indicated the presence of both metals in the gills and hepatopancreas of the animals regardless of depuration time. This study reveals how cadmium bioaccumulation kinetics may differ between repeated ‘pulse’ exposures where, unlike zinc, the rate of uptake decreases with each successive pulse. This demonstrates how repeated exposures, rather than a constant exposure, can influence the bioaccumulation kinetics of metals, highlighting the important consideration for incorporating pulsed toxicity tests in frameworks when deriving WQG values.
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    Towards sustainable environmental quality: priority research questions for the Australasian region of Oceania
    (John Wiley & Sons, Inc, 2019-07-05) Gaw, S; Harford, A; Pettigrove, VJ; Sevicke-Jones, G; Manning, T; Ataria, J; Cresswell, T; Dafforn, KA; Leusch, FDL; Moggridge, B; Cameron, M; Chapman, J; Coates, G; Colville, A; Death, C; Hageman, K; Hassell, KL; Hoak, M; Gadd, JB; Jolley, DF; Karami, A; Kotzakoulakis, K; Lim, R; McRae, N; Metzeling, L; Mooney, T; Myers, J; Pearson, A; Saaristo, M; Sharley, D; Stuthe, J; Sutherland, O; Thomas, O; Tremblay, L; Wood, W; Boxall, ABA; Rudd, MA; Brooks, BW
    Environmental challenges persist across the world, including the Australasian region of Oceania, where biodiversity hotspots and unique ecosystems such as the Great Barrier Reef are common. These systems are routinely affected by multiple stressors from anthropogenic activities, and increasingly influenced by global megatrends (e.g., the food–energy–water nexus, demographic transitions to cities) and climate change. Here we report priority research questions from the Global Horizon Scanning Project, which aimed to identify, prioritize, and advance environmental quality research needs from an Australasian perspective, within a global context. We employed a transparent and inclusive process of soliciting key questions from Australasian members of the Society of Environmental Toxicology and Chemistry. Following submission of 78 questions, 20 priority research questions were identified during an expert workshop in Nelson, New Zealand. These research questions covered a range of issues of global relevance, including research needed to more closely integrate ecotoxicology and ecology for the protection of ecosystems, increase flexibility for prioritizing chemical substances currently in commerce, understand the impacts of complex mixtures and multiple stressors, and define environmental quality and ecosystem integrity of temporary waters. Some questions have specific relevance to Australasia, particularly the uncertainties associated with using toxicity data from exotic species to protect unique indigenous species. Several related priority questions deal with the theme of how widely international ecotoxicological data and databases can be applied to regional ecosystems. Other timely questions, which focus on improving predictive chemistry and toxicology tools and techniques, will be important to answer several of the priority questions identified here. Another important question raised was how to protect local cultural and social values and maintain indigenous engagement during problem formulation and identification of ecosystem protection goals. Addressing these questions will be challenging, but doing so promises to advance environmental sustainability in Oceania and globally. © 2019 The Authors