ANSTO :: Browsing by Author "Simpson, SL"

Browsing by Author "Simpson, SL"

Now showing 1 - 14 of 14

Bioaccumulation and retention kinetics of cadmium in the freshwater decapod Macrobrachium australiense
(Elsevier, 2014-03) Cresswell, T; Simpson, SL; Smith, REW; Nugegoda, D; Mazumder, D; Twining, JR
The potential sources and mechanisms of cadmium bioaccumulation by the native freshwater decapods Macrobrachium species in the waters of the highly turbid Strickland River in Papua New Guinea were examined using 109Cd-labelled water and food sources and the Australian species Macrobrachium australiense as a surrogate. Synthetic river water was spiked with environmentally relevant concentrations of cadmium and animals were exposed for 7 days with daily renewal of test solutions. Dietary assimilation of cadmium was assessed through pulse-chase experiments where prawns were fed separately 109Cd-labelled fine sediment, filamentous algae and carrion (represented by cephalothorax tissue of water-exposed prawns). M. australiense readily accumulated cadmium from the dissolved phase and the uptake rate increased linearly with increasing exposure concentration. A cadmium uptake rate constant of 0.10 ± 0.05 L/g/d was determined in synthetic river water. During depuration following exposure to dissolved cadmium, efflux rates were low (0.9 ± 5%/d) and were not dependent on exposure concentration. Assimilation efficiencies of dietary sources were comparable for sediment and algae (48–51%), but lower for carrion (28 ± 5%) and efflux rates were low (0.2–2.6%/d) demonstrating that cadmium was well retained by M. australiense. A biokinetic model of cadmium accumulation by M. australiense predicted that for exposures to environmentally relevant cadmium concentrations in the Strickland River, uptake from ingestion of fine sediment and carrion would be the predominant sources of cadmium to the organism. The model predicted the total dietary route would represent 70–80% of bioaccumulated cadmium © 2014, Elsevier B.V.
Bioaccumulation kinetics and organ distribution of cadmium and zinc in the freshwater decapod crustacean macrobrachium australiense
(ACS Publications, 2014-12-24) Cresswell, T; Simpson, SL; Mazumder, D; Callaghan, PD; Nguyen, AP
This study used the radioisotopes 109Cd and 65Zn to explore the uptake, retention and organ distribution of these nonessential and essential metals from solution by the freshwater decapod crustacean Macrobrachium australiense. Three treatments consisting of cadmium alone, zinc alone, and a mixture of cadmium and zinc were used to determine the differences in uptake and efflux rates of each metal individually and in the metal mixture over a three-week period, followed by depuration for 2 weeks in metal-free water using live-animal gamma-spectrometry. Following exposure, prawns were cryosectioned and the spatial distribution of radionuclides visualized using autoradiography. Metal uptake and efflux rates were the same in the individual and mixed-metal exposures, and efflux rates were close to zero. The majority of cadmium uptake was localized within the gills and hepatopancreas, while zinc accumulated in the antennal gland at concentrations orders of magnitude greater than in other organs. This suggested that M. australiense may process zinc much faster than cadmium by internally transporting the accumulated zinc to the antennal gland. The combination of uptake studies and autoradiography greatly increases our understanding of how metal transport kinetics and internal processing may influence the toxicity of essential and nonessential metals in the environment. © 2014 American Chemical Society
Bioaccumulation of 65Zn by the Sydney rock oyster (Saccostrea glomerata) from dissolved and particulate phases
(SETAC Australasia, 2014-09) Lee, JH; Birch, GF; Cresswell, T; Payne, TE; Simpson, SL
Oysters and other similar bivalves are popular ‘biomonitors’ or ‘sentinels’ of the environment and are commonly used to assess the health of marine ecosystems. It has been generally accepted that uptake and bioaccumulation in bivalves is influenced predominantly by dietary ingestion of contaminated particles as well as from dissolved sources. An organism of relevance to Australian ecosystems is the Sydney rock oyster (SRO; Saccostrea glomerata), an intertidal, suspension filter-feeder commonly found on the coasts and estuaries of Victoria, New South Wales, and Queensland, Australia. Farmed SRO organisms were used for a 2 month mesocosm study where specimens were exposed to a gradient of resuspended sediment loads and sediment-bound trace metal concentrations. The results indicated poor correlations between SRO tissue metal concentrations and either sediment metal concentration or resuspended volume, with the greatest bioaccumulation being observed in the control tank containing no sediment. These results suggested that SRO metal bioaccumulation was driven primarily from a dissolved source. To investigate this further, a radiotracer study using the gamma-emitting radioisotope 65Zn was conducted, in which SRO organisms were exposed to the dissolved 65Zn radioisotope at three concentrations (5, 25 and 50 µg/L) for 4 days, followed by 20 days of depuration. Dietary assimilation of Zn was examined through pulse-chase experiments where SRO specimens were fed either 65Zn labelled fine-fraction sediments in suspension, or algae. The outcome of this experiment was to outline the relative importance of dissolved, sedimentary, and algal metal sources, and conclusively determine the primary uptake pathway for metal bioaccumulation. The resulting data were used to establish uptake and efflux rate constants from dissolved sources, and assimilation efficiencies from the dietary sources, which were then incorporated into a biodynamic accumulation model. The results of this study are discussed in the context of the use of bivalves as indicators of sediment quality.
Challenges in understanding the sources of bioaccumulated metals in biota inhabiting turbid river systems
(Springer Link, 2014-01) Cresswell, T; Smith, REW; Simpson, SL
Bioaccumulation of As, Cd, Cu, Pb and Zn by Macrobrachium prawns was observed to occur in the Strickland River downstream of a gold mine at Porgera, Papua New Guinea. This was despite the total metal concentrations of waters and sediments indicating no difference from reference sites within tributaries. To provide information on potential sources and bioavailability of metals to prawns, an extensive range of analyses were made on waters, suspended solids, deposited sediments and plant materials within the river system. Dissolved metal concentrations were mostly sub-micrograms per liter and no major differences existed in concentrations or speciation between sites within the Strickland River or its tributaries. Similarly, no differences were detected between sites for total or dilute acid-extractable metal concentrations in bed sediments and plant materials, which may be ingested by the prawns. However, the rivers in this region are highly turbid and the dilute acid-extractable cadmium and zinc concentrations in suspended solids were greater at sites in the Strickland River than at sites in tributaries. The results indicated that mine-derived inputs increased the proportion of these forms of metals or metalloids in the Strickland River. These less strongly bound metals and metalloids would be more bioavailable to the prawns via the dietary pathway. The results highlighted many of the difficulties in using routine monitoring data without information on metal speciation to describe metal uptake and predict potential effects when concentrations are low and similar to background. The study indicated that the monitoring of contaminant concentrations in organisms that integrate the exposure from multiple exposure routes and durations may often be more effective for detecting impacts than intermittent monitoring of contaminants in waters and sediments. © 2020 Springer Nature Switzerland AG.
Challenges with tracing the fate and speciation of mine-derived metals in turbid river systems: implications for bioavailability
(Springer, 2013-11-01) Cresswell, T; Smith, REW; Nugegoda, D; Simpson, SL
The fast-flowing and highly turbid Lagaip River (0.5-10 g/L suspended solids) in the central highlands of Papua New Guinea receives mine-derived metal inputs in both dissolved and particulate forms. Nearest the mine, metal concentrations in suspended solids were 360, 9, 90, 740 and 1,300 mg/kg for As, Cd, Cu, Pb and Zn, while dissolved concentrations were 2.7, 0.6, 3.1, 0.1 and 25 mu g/L, respectively. This creates a significant metal exposure source for organisms nearer the mine. However, because the Lagaip River is diluted by a large number of tributaries, the extent to which mine-derived metals may affect biota in the lower catchments is uncertain. To improve our understanding of the forms of potentially bioavailable metals entering the lower river system, we studied the partitioning and speciation of metals within the Lagaip River system. Dissolved and particulate metal concentrations decreased rapidly downstream of the mine due to dilution from tributaries. As a portion of the particulate metal concentrations, the more labile dilute acid-extractable forms typically comprised 10-30 % for As and Pb, 50-75 % for Cu and Zn, and 50-100 % for Cd. Only dissolved Cd, Cu and Zn remained elevated relative to the non-mine-impacted tributaries (< 0.03, 0.5 and 0.3 mu g/L), but the concentrations did not appreciably change with increasing dilution downriver. This indicated that release of Cd, Cu and Zn was likely occurring from the more labile metal phases of the mine-derived particulates. Chelex-labile metal analyses and speciation modelling indicated that dissolved copper and lead were largely non-labile and likely complexed by naturally occurring organic ligands, while dissolved cadmium and zinc were predominantly present in labile forms. The study confirmed that mine-derived particulates may represent a significant source of dissolved metals in the lower river system; however, comparison with water quality guidelines indicates the low concentrations would not adversely affect aquatic life.© 2013, Springer
Comparing trace metal bioaccumulation characteristics of three freshwater decapods of the genus Macrobrachium
(Elsevier, 2014-07-01) Cresswell, T; Smith, REW; Nugegoda, D; Simpson, SL
Potential sources and kinetics of metal bioaccumulation by the three Macrobrachium prawn species M. australiense, M. rosenbergii and M. latidactylus were assessed in laboratory experiments. The prawns were exposed to two scenarios: cadmium in water only; and exposure to metal-rich mine tailings in the same water. The cadmium accumulation from the dissolved exposure during 7 days, followed by depuration in cadmium-free water for 7 days, was compared with predictions from a biokinetic model that had previously been developed for M. australiense. M. australiense and M. latidactylus accumulated significant tissue cadmium during the exposure phase, albeit with different uptake rates. All three species retained >95% of the bioaccumulated cadmium during the depuration phase, indicating very slow efflux rates. Following exposure to tailings, there were significant (p < 0.05) differences in tissue arsenic, cadmium, lead and zinc concentrations among species. Cadmium and zinc concentrations were increased relative to controls for all three species but were not different between treatments (direct/indirect contact with tailings), suggesting these metals were primarily accumulated via the dissolved phase. All species bioaccumulated significantly greater arsenic and lead when in direct contact with mine tailings, demonstrating the importance of an ingestion pathway for these metals. Copper was not bioaccumulated above control concentrations for any species. The differences between the metal accumulation of the three prawns indicated that a biokinetic model of cadmium bioaccumulation for M. australiense could potentially be used to describe the metal bioaccumulation of the other two prawn species, albeit with an over-prediction of 3–9 times. Despite these being the same genus of decapod crustacean, the study highlights the issues with using surrogate species, even under controlled laboratory conditions. It is recommended that future studies using surrogate species quantify the metal bioaccumulation characteristics of each species in order to account for any differences between species.© 2014, Elsevier B.V.
Dietary ingestion of fine sediments and microalgae represent the dominant route of exposure and metal accumulation for Sydney rock oyster (Saccostrea glomerata): a biokinetic model for zinc
(Elsevier, 2015-08-01) Lee, JH; Birch, GF; Cresswell, T; Johansen, MP; Adams, MS; Simpson, SL
Past studies disagree on the extent to which dissolved or dietary uptake contribute to metal bioaccumulation in the filter-feeding Sydney rock oyster (Saccostrea glomerata) in urbanized estuaries. Although most data support the assumption that fine sediments are a major route of metal uptake in these bivalves, some studies based in the Sydney estuary, Australia, have indicated a poor correlation. In the present study, seawater, sediment and microalgae were radiolabelled with 65Zn tracer and exposed to S. glomerata to assess the influence of dissolved and dietary sources to Zn bioaccumulation. Oysters in the dissolved-phase uptake experiment (5, 25 and 50 μg L−1 65Zn for 4 d followed by 21 days of depuration) readily accumulated 65Zn for all three concentrations with an uptake rate constant of 0.160 ± 0.006 L dry weight g−1 d−1. Oysters in the dietary assimilation experiment (1 h pulse-feed of either 65Zn-radiolabelled suspended fine-fraction (<63 μm) sediment or the microalgae Tetraselmis sp.) accumulated 65Zn, with assimilation efficiencies of 59 and 67% for fine sediment and microalgae, respectively. The efflux rates were low for the three experiments (0.1–0.5% d−1). A bioaccumulation kinetic model predicts that uptake of Zn will occur predominantly through the dietary ingestion of contaminated fine sediment particles and microalgae within the water column, with considerably greater metal bioaccumulation predicted if oysters ingested microalgae preferentially to sediments. However, the model predicts that for dissolved Zn concentrations greater than 40 μg L−1, as observed during precipitation events, the uptake of the dissolved phase may contribute ≥50% to accumulation. Overall, the results of the present study suggest that all three sources may be important exposure routes to S. glomerata under different environmental conditions, but contributions from dietary exposure will often dominate. © 2015 Elsevier
Investigating the kinetics of Cd transport between internal organs of the freshwater decapod Macrobrachium australiense
(SETAC, 2014-09-14) Cresswell, T; Simpson, SL; Mazumder, D; Callaghan, PD; Nguyen, AP; Corry, M
The bioaccumulation of metals by aquatic organisms can be studied in great detail using radiotracers, allowing insights into rates of uptake and fate of the metals accumulated in tissues. While there have been numerous studies on the whole-body bioaccumulation of metals by organisms, little is known about the kinetics of organ-specific bioaccumulation. This study used the radioisotope 109Cd to explore the internal uptake kinetics of this non-essential metal following accumulation from solution by the freshwater decapod crustacean Macrobrachium australiense. The first stage of the study involved exposing 24 organisms for up to 2 weeks to 0.55 µg Cd/L in synthetic river water with three individuals being removed at pre-defined time points. Following exposure, animals were rinsed in a 0.1 mM EDTA solution to remove any loosely-bound metal, rapidly frozen and the anatomical distribution of the radionuclide visualised from fresh frozen sections (20 um) using autoradiography. The second phase of the study consisted of exposing organisms to the same radiotracer solution for a short period (6 h) and long period (7 d), followed by depuration in metal- and isotope-free water for up to 3 weeks. Organisms were removed from depuration at pre-defined time points, rapidly frozen, the anatomical distribution of the radionuclide determined as above. Preliminary results suggest that the gills appeared to saturate after 7 d exposure, with negligible increase over another 7 d of exposure. However, the ratio of Cd between the hepatopancreas and gills increased over time, suggesting the organism was actively processing accumulated metal. Rates of accumulation into different internal compartments in response to changes in uptake and depuration durations will be discussed. The findings of the study provide new information on the processing of a non-essential metal by M. australiense and could potentially be used to estimate the exposure history of field-caught organisms.
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.
Metal speciation and potential bioavailability changes during discharge and neutralisation of acidic drainage water
(Elsevier, 2014-05) Simpson, SL; Vardanega, CR; Jarolimek, C; Jolley, DF; Angel, BM; Mosely, LM
The discharge of acid drainage from the farm irrigation areas to the Murray River in South Australia represents a potential risk to water quality. The drainage waters have low pH (2.9–5.7), high acidity (up to 1190 mg L−1 CaCO3), high dissolved organic carbon (10–40 mg L−1), and high dissolved Al, Co, Ni and Zn (up to 55, 1.25, 1.30 and 1.10 mg L−1, respectively) that represent the greatest concern relative to water quality guidelines (WQGs). To provide information on bioavailability, changes in metal speciation were assessed during mixing experiments using filtration (colloidal metals) and Chelex-lability (free metal ions and weak inorganic metal complexes) methods. Following mixing of drainage and river water, much of the dissolved aluminium and iron precipitated. The concentrations of other metals generally decreased conservatively in proportion to the dilution initially, but longer mixing periods caused increased precipitation or adsorption to particulate phases. Dissolved Co, Mn and Zn were typically 95–100% present in Chelex-labile forms, whereas 40–70% of the dissolved nickel was Chelex-labile and the remaining non-labile fraction of dissolved nickel was associated with fine colloids or complexed by organic ligands that increased with time. Despite the different kinetics of precipitation, adsorption and complexation reactions, the dissolved metal concentrations were generally highly correlated for the pooled data sets, indicating that the major factors controlling the concentrations were similar for each metal (pH, dilution, and time following mixing). For dilutions of the drainage waters of less than 1% with Murray River water, none of the metals should exceed the WQGs. However, the high concentrations of metals associated with fine precipitates within the receiving waters may represent a risk to some aquatic organisms. © 2013, Elsevier Ltd.
Metal transfer among organs following short- and long-term exposures using autoradiography: cadmium bioaccumulation by the freshwater prawn macrobrachium australiense
(American Chemical Society, 2017-03-16) Cresswell, T; Mazumder, D; Callaghan, PD; Nguyen, AP; Corry, M; Simpson, SL
The uptake, depuration, and organ distribution of the radioisotope 109Cd were used to explore the internal kinetics of this nonessential metal following accumulation from waterborne cadmium by the freshwater decapod crustacean Macrobrachium australiense. Short- (6 h) and long-term (7 to 14 days) exposures to the radioisotope in solutions of 0.56 μg Cd/L were followed by depuration in metal- and isotope-free water for up to 21 days. The anatomical distribution of the radionuclide was visualized using autoradiography at predefined time points. The gills did not become saturated with cadmium after 14 days of exposure and demonstrated a greater rate of cadmium uptake relative to the hepatopancreas. Cadmium concentrations decreased rapidly during depuration from both gills and hepatopancreas after short exposures but slowly following long-term exposures. This suggests that the duration of cadmium exposure influences the depuration rate for this organism. The study demonstrates the complex behavior of cadmium accumulated by M. australiense and improves our understanding of how exposure duration will influence the internal location and potential toxicity of metals. © 2017 American Chemical Society
Radioisotope techniques and aquatic ecotoxicology: importance of understanding kinetics and internal location of metals
(University of New South Wales and Australian Nuclear Science and Technology Organisation, 2015-07-08) Cresswell, T; Mazumder, D; Callaghan, PD; Nguyen, AP; Corry, M; Simpson, SL
Aquatic ecotoxicology is primarily concerned with the bioaccumulation and effects of anthropogenic contaminants to a range of biota. Traditional methods of assessing the bioaccumulation of contaminants by an organism have typically relied on destructive techniques, generally involving the dissection of internal organs, followed by acid digestion and analysis. To understand how organisms accumulate contaminants over time using these traditional methods, a large number of organisms was required to be sacrificed. Gamma-emitting metal radioisotopes are valuable tools for studying metal bioaccumulation in aquatic invertebrates, allowing the influx and efflux of multiple metals to be analysed rapidly, at multiple intervals in live organisms during an exposure period (Hervé-Fernández et al., 2010, Cresswell et al., 2015). Furthermore, autoradiography of sacrificed and cryosectioned organisms enables the organ distribution of accumulated metals to be visualised and quantified. To cryosection, organisms are snap-frozen to limit the mobilisation of chemical species, preserve the integrity of the organs and allow much higher resolution of organ-specific metal analysis compared to tradition dissection-digestion techniques. This paper describes two studies on a freshwater decapod crustacean that examined the kinetics of non-essential (cadmium) and essential (zinc) metal accumulation in a mixture, and the kinetics of internal partitioning of cadmium among major organs using radioisotope techniques to model environmental conditions.
Sources and mechanisms of cadmium bioaccumulation by the freshwater decapod crustacean Macrobrachium australiense
(Society of Environmental Toxicology and Chemistry, 2012-05-20) Cresswell, T; Simpson, SL; Twining, JR; Mazumder, D; Smith, REW; Nugegoda, D
Metal bioaccumulation by aquatic invertebrates in the environment can often be explained by chemical parameters such as metal concentrations within the solution and particulate phases by exposure-dose-response relationships. Simple relationships of this type are not known for invertebrates in the highly turbid Strickland River, Papua New Guinea. Here, indigenous prawns demonstrate significant differences in bioaccumulated metal concentrations (predominantly cadmium) between populations exposed to mining effluents compared to those in reference tributaries. However, metal concentrations of waters and sediments are not significantly different between sites. This study investigated the potential sources and mechanisms of cadmium (Cd) bioaccumulation by the freshwater decapod Macrobrachium australiense using 109Cd-labelled 70 SETAC 6th World Congress/SETAC Europe 22nd Annual Meeting water and food sources. Synthetic river water (SRW) was spiked with environmentally relevant concentrations of Cd and prawns were exposed for seven days with daily renewal of test solutions. Prawns were subsequently allowed to depurate in Cd-free SRW for fourteen days. Dietary assimilation of Cd was assessed through pulse-chase experiments where prawns were fed 109Cd-labelled fine sediment, filamentous algae and carrion (represented by cephalothorax tissue of water-exposed prawns). Radioanalyses during the exposures were used to determine influx and efflux rate constants for Cd in water, and the assimilation efficiency (AE) and efflux rate (Ke) of Cd from each dietary source. Results indicated that M. australiense readily uptake Cd from solution and that uptake rate increased linearly with increasing exposure concentration. During depuration, water efflux rates were low (0.9 ± 5 % d-1) and were not dependent on exposure concentration. AEs of dietary sources were comparable for sediment and algae (approx 50 %), but lower for carrion (33 %) and efflux rates were low (0.2-2.6 % d-1). The results demonstrated that prawns are likely to bioaccumulate Cd readily from both water and food sources. The rapid uptake but slow efflux of bioaccumulated Cd may explain why monthly or weekly measurements of Cd in water and sediments provide inadequate information regarding exposure or dose to explain metal accumulation patterns. A biokinetic model of Cd accumulation by M. australiense is presented based on the findings.
Where do the metals go? Investigating uptake, retention and spatial distribution of cadmium and zinc using radiotracers within a freshwater decapod crustacean
(SETAC Australasia, 2013-10-01) Cresswell, T; Simpson, SL; Mazumder, D; Callaghan, PD; Nguyen, AP
The bioaccumulation of metals by aquatic organisms can be studied in great depth using radiotracers, allowing insights into rates of uptake and fate of the metals once bioaccumulated. This study used the radioisotopes 109Cd and 65Zn to explore the uptake, retention and internal distribution of these non-essential and essential metals in solution by the freshwater decapod crustacean Macrobrachium australiense. Three treatments consisting of cadmium alone, zinc alone and a combination of cadmium and zinc were used to determine the differences in uptake rate of each metal individually and in a mixture over a three week period. The prawns were then allowed to depurate in metal-free water for two weeks to determine rates of efflux. The effects of moulting on the uptake and loss of each metal radionuclide were also identified during the study. Following exposure, prawns were cryosectioned and the spatial distribution of radionuclides visualised using autoradiography for the 3 experimental cohorts. Results showed that a mixture of the two metals did not affect the uptake or efflux rate of each individual metal. Moulting appeared to result in a short-term loss in zinc but an increased cadmium uptake rate. However, metal isotope concentration remained stable within the body during the depuration period. Autoradiography demonstrated that the majority of cadmium uptake was localised within the hepatopancreas, while zinc uptake was distributed between the hepatopancreas and the exoskeleton. The implications of the study are such that M. australiense readily accumulates both cadmium and zinc from solution but does not effectively eliminate either metal while in metal-free water. © 2013, ANSTO and CSIRO.

Browsing by Author "Simpson, SL"

Results Per Page

Sort Options