Browsing by Author "Barry, LA"
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- ItemANSTO AMS facility sample processing and target preparation: an update(20th International Radiocarbon Conference, 2009-06-01) Jacobsen, GE; Barry, LA; Bertuch, F; Hua, Q; Mifsud, C; Pratap, P; Reilly, N; Varley, S; Williams, AGThe ANSTO AMS Facility has been operating for the past 17 years, and comprises two accelerators complemented with a suite of chemistry laboratories dedicated to the processing of samples for carbon, beryllium, aluminium, iodine, and actinide analyses. The facility performs and supports a wide range of research in the areas of paleoclimate change, water resource sustainability, archaeology, geomorphology, and nuclear safeguards. As a result, the chemistry laboratories are called upon to process a large variety of sample types and increasing numbers of samples. The radiocarbon laboratories process charcoal, wood, sediments, pollen, carbonates, waters, textiles, and bone though the pretreatment stages, combustion or hydrolysis, and graphitization. Over the years, we have continually worked to improve pretreatment methods, reduce sample size, and reduce background. Construction of a dedicated low-background combustion and graphitization system is underway. The cosmogenic laboratories process quartz-bearing rocks and sediments through cleaning, dissolution, separation, and purification of Be and Al and preparation of targets as oxides. In this poster, we will summarize the current methods and developments in the radiocarbon and cosmogenic chemistry laboratories.
- ItemApplication of stable isotope mixing models for defining trophic biomagnification pathways of mercury and selenium(American Society of Limnology and Oceanography, 2014-07-01) Jones, HJ; Swadling, KM; Butler, ECV; Barry, LA; Macleod, CKTrophic models based on nitrogen stable isotope ratios (delta N-15) have been shown to predict changes in mercury (Hg) concentrations in fish; however, they are usually applied at the ecosystem scale and are rarely directed at known trophic pathways. We discuss a novel approach in which we combined gut contents analysis and stable isotope analyses (delta N-15 and delta C-13) into a Bayesian isotopic mixing model to provide a quantitative estimate of Hg and selenium (Se) biomagnification in an estuarine food web. Estimates of the relationship between total mercury (THg) and methylmercury (MeHg) were significantly improved in mixing model-adjusted food webs over models that included all known prey sources. Spatial differences in dietary composition and MeHg bioavailability offer strong evidence that local food webs can have a significant effect on the biomagnification of Hg within benthic fish species. While no evidence of Se biomagnification was found, lower Se : Hg ratios at higher trophic levels could be attributed to increasing trophic Hg concentration. Furthermore, stable isotope analysis suggested Hg and Se biotransfer from benthic sources to fish. Overall, the findings highlight that isotope mixing models can be a significant aid in assessments of contaminant biomagnification, particularly when it is important to define food pathways to top predators. © 2014, American Society of Limnology and Oceanography.
- ItemHolocene ecosystem change in Little Llangothlin Lagoon, Australia: implications for the management of a Ramsar-listed wetland(Springer Nature, 2016-01-01) Woodward, C; Shulmeister, J; Zawadzki, A; Child, DP; Barry, LA; Hotchkis, MACWe present new chironomid and stable isotope (δ13C and δ15N) data from Little Llangothlin Lagoon, Australia that provides more detail on changes in this wetland since European settlement ca. 1840 AD. We also examine how the updated Holocene paleoecological record provides insights for management of this Ramsar-listed wetland. The current management strategy for Little Llangothlin is to restore the wetland and catchment to its natural state. This strategy is intended to protect the values that allowed it to be listed as a Ramsar wetland; i.e. its role as a drought refuge for waterbirds and to preserve or enhance threatened ecological communities. There are clear conflicts between the Ramsar listing criteria, management objectives and the management strategy in light of information provided by the palaeoecological record. In particular, restoration of terrestrial ecosystems through reforestation may jeopardise the wetlands role as a drought refuge. Some activities, such as artificial raising of the water level in 1989 are intended to restore, but actually introduced a state that did not exist prior to human settlement. We recommend a more integrated management approach that heeds the information provided by the palaeoecological record and focuses more on maintenance or enhancement of ecosystem services and biodiversity. © 2016, Springer
- ItemThe indirect response of an aquatic ecosystem to long-term climate-driven terrestrial vegetation in a subalpine temperate lake(John Wiley & Sons, Inc, 2017-12-15) Beck, KK; Fletcher, MS; Kattel, G; Barry, LA; Gadd, PS; Heijnis, H; Jacobsen, GE; Saunders, KMAim To assess whether climate directly influences aquatic ecosystem dynamics in the temperate landscape of Tasmania or whether the effects of long-term climatic change are mediated through the terrestrial environment (indirect climate influence). Location Paddy's Lake is located at 1065 m a.s.l. in temperate north-west Tasmania, a continental island south-east of mainland Australia (41°15–43°25′ S; 145°00–148°15′ E). Methods We developed a new 13,400 year (13.4 kyr) palaeoecological dataset of lake sediment subfossil cladocerans (aquatic grazers), bulk organic sediment carbon (C%) and nitrogen (N%) and δ13C and δ15N stable isotopes. Comparison of this new data was made with a recently published pollen, geochemistry and charcoal records from Paddy's Lake. Results Low cladoceran diversity at Paddy's Lake is consistent with other temperate Southern Hemisphere lakes. The bulk sediment δ15N values demonstrate a significant lagged negative response to pollen accumulation rate (pollen AR). Compositional shifts of dominant cladoceran taxa (Bosmina meridionalis and Alona guttata) occur following changes in both pollen AR and pollen (vegetation) composition throughout the 13.4 kyr record at Paddy's Lake. The δ15N values demonstrate a significant positive lagged relationship to the oligotrophic:eutrophic cladoceran ratio. Main conclusions Long-term changes in cladoceran composition lag changes in both pollen AR and terrestrial vegetation composition. We interpret pollen AR as reflecting climate-driven changes in terrestrial vegetation productivity and conclude that climate-driven shifts in vegetation are the principal driver of the cladoceran community during the last ca. 13.4 kyr. The significant negative lagged relationship between pollen AR and δ15N reflects the primary control of vegetation productivity over within-lake nutrient status. Thus, we conclude that the effects of long-term climate change on aquatic ecosystem dynamics at our site are indirect and mediated by the terrestrial environment. Vegetation productivity controls organic soil development and has a direct influence over lake trophic status via changes in the delivery of terrestrial organic matter into the lake. © 2017 John Wiley & Sons Ltd
- ItemInsights from stable isotopes for evaluating weed invasion in urban bushland(University of New South Wales and Australian Nuclear Science and Technology Organisation, 2015-07-08) Beer, J; Chagué-Goff, C; Andrew, AS; Barry, LAWhy is Pittosporum undulatum taking over in Sydney’s urban bushland? Bush regeneration manuals recommend removing the native shrub Pittosporum undulatum because it creates shady conditions suppressing regeneration of other native plants. We used stable isotope analysis to compare the water use efciency and nutrient cycling processes of Pittosporum with other plant species to determine why it has a competitive edge in urban bushland. We collected plant, litter and soil samples from eight sites along Wolli Creek in southern Sydney. Four sites were dominated by exotic weeds and Pittosporum undulatum (‘weedy' sites), while the other four sites were dominated by native vegetation species (‘native' sites). Plant, litter and soil samples were analysed for %C, %N, δ13C and δ15N. Plant material and litter at ‘native’ sites had a higher carbon content and lower nitrogen content compared to ‘weedy‘ sites. Soil and Pittosporum undulatum had similar %C and %N values regardless of whether they were collected from ‘native’ or ‘weedy’ sites. Initial results indicate that native species and exotic species had distinct δ13C values in their mature leaf tissue, suggesting higher water use efficiency of native plants. Pittosporum undulatum had a similar isotopic signature to other native species. Nitrogen isotope results show plant species have unique δ15N values reecting unique N capture strategies. Soil δ15N signatures were variable. Pittosporum undulatum was expected to be similar to the exotic plants in terms of isotopic signature, assuming that this native species is utilising resources in a similar way to invasive exotic species. Our pilot study indicates this is not the case, and thus nativespecies may be becoming dominant in urban bushland through other mechanisms. Further research is required to understand how nutrients are captured and cycled in urban bushland.
- ItemMorphological analysis and radiocarbon dating of non-returning boomerangs from Cooper Creek/Kinipapa (Northeast South Australia)(Taylor & Francis, 2021-11-03) Roberts, A; Freeman, S; Wesley, D; Levchenko, VA; Barry, LA; Bordes, L; Litherland, K; Litherland, J; Haynes, J; Paterson, AIn this article we present the results of a morphological analysis of four mostly complete non-returning boomerangs and one shaped wooden fragment recovered in 2017 and 2018 from Cooper Creek near Innamincka in South Australia’s far northeast. This archaeological collection forms one of only six known/published wooden artefact assemblages in the country. We also detail the results of the direct accelerator mass spectrometry radiocarbon (AMS 14C) measurement of the artefacts which range from circa 275–175 BP (1650–1830 cal AD, median ages reported). Given that the age estimates obtained for the artefacts are from the recent period, we have complemented the morphological analysis by interpreting the assemblage within the context of ethnohistorical records and Traditional Owner knowledge. The assemblage reveals a variety of forms and functions representative of the diverse cultural activities and daily lives of the Aboriginal people who lived near significant waterholes in the Cooper Creek region during this period. The boomerangs also preserve manufacture and use-wear traces, providing insights into the life histories of each implement. In addition to their likely use as projectiles, our results indicate that the boomerangs were probably used for fighting, hunting, digging, fire management and possibly in ceremonies. Predictions for climate change in the region threaten to alter the conditions that allowed the preservation of these artefacts which may negatively affect the potential survival of other wooden objects that remain in the environment. © 2024 Informa UK Limited
- ItemPalaeoecological evidence for sustained change in a shallow Murray River (Australia) floodplain lake: regime shift or press response(Springer Link, 2017-02-01) Kattel, G; Gell, PA; Zawadzki, A; Barry, LAPaleolimnological techniques can reveal long-term perturbations and associated stable state transitions of lake ecosystems. However, such transitions are difficult to predict since changes to lake ecosystems can be abrupt or gradual. This study examined whether there were past transitions in the ecological regime of Kings Billabong, a shallow River Murray wetland in southeast Australia. A 94-cm-long core, covering c. 90 years of age, was analysed at 1 cm resolution for subfossil cladocerans, diatoms and other proxies. Prior to river regulation (c. 1930), the littoral to planktonic ratios of cladocerans and diatoms, and bulk sediment δ13C values were high, while the period from c. 1930 to c. 1970 experienced considerable changes to the wetland ecosystem. The abrupt nature of changes of planktonic cladocerans and diatoms, particularly after the onset of river regulation (1930s), was triggered by inundation, high rates of sedimentation and shifts in bulk sediment δ15N values. However, the transition of a once littoral-dominated community, to one favouring an increasingly turbid, plankton-dominated trophic condition following river regulation was relatively slow and lasted for decades. The progression to a new regime was likely delayed by the partial recovery of submerged plant communities and related internal dynamics.© 2016, Springer International Publishing Switzerland.
- ItemPaleolimological investigation of the use of stable isotopes of carbon and nitrogen in bulk sediment and cladoceran zooplankton to reveal ecosystem changes in Kings Billaong Northwest Victoria, Australia(University of Western Australia, 2013-07-10) Kattel, G; Gell, PA; Zawadzki, A; Barry, LANorthwest Victoria hosts a large number of shallow floodplain wetlands along the Murray River system. One of these, Kings Billabong, is known for its high conservation values. However, the naturally occurring flood pulses, which maintain ecological connectivity between river and wetlands, have been altered impacting the ecology of Kings Billabong. The human-induced river regulation in the Murray River following the arrival of Europeans, and increased farming activities around Mildura for irrigation, has switched Kings Billabong to a permanent water regime resulting in accelerated sedimentation rates and changed sources of carbon and, subsequently, altered ecological character. This study focuses on a 90 cm long sediment core taken from Kings Billabong in 2011, where the 210Pb dating detected sediments at c. 60 cm depth to be c. 65 years old. Around this time (c. 1940-1945 AD), a systemic change occurred in the billabong. The enrichment of carbon substantially declined, while, in the meantime, nitrogen enrichment increased. Coincidently, the subfossil cladoceran zooplankton assemblages revealed changes in the limnological conditions of the wetland ecosystem. Among the littoral species, the Chydorus sphaericus group, which prefers eutrophic water, became dominant. Since the early 2000s, the abundance of Biapertura affinis, a pioneer plant dwelling species, has declined. Before the assemblage of B. affinis began to decline, a large number of cladoceran ephippia were recorded in sediment samples indicating the elevated stress in the wetland. This study suggests that paleolimnological investigations, together with the use of stable isotopes of carbon and nitrogen in sediment samples, provides an opportunity to reveal the impacts of anthropogenic disturbances on the floodplain wetlands of the Murray River system across northwest Victoria, and potentially more widely across Australia. © The Authors.
- ItemSpring root-zone temperature regulates root growth, nutrient uptake and shoot growth dynamics in grapevines(Wiley, 2015-08-06) Clark, SJ; Lamont, KJ; Pan, HY; Barry, LA; Hall, A; Rogiers, SYAbstract Background and Aims Environmental factors such as root-zone temperature can influence plant development. Linkages between spring soil temperature, carbohydrate reserve mobilisation, nutrient uptake and nitrogen partitioning were investigated in Shiraz grapevines to gain better understanding of how this abiotic factor can alter root and canopy development. Methods and Results Plants were exposed to a cool, an ambient or a warm root-zone temperature over a 9-week period from budburst. Root starch mobilisation was correlated to the sum of cumulative heat units absorbed by the soil (soil growing degree days, GDDsoil) and this contributed to greater fine root density and extent of root branching. Most macronutrients, including N, accumulated to greater concentration in the leaves of vines exposed to the warm root-zones. Patterns of 15N accumulation indicated that despite greater fertiliser-N uptake in the warm root-zone treatment, most of the N that accumulated in the shoots was the result of N reserve mobilisation. Warmed root-zones resulted in plants with accelerated leaf emergence, extended internodes and elongated shoots with larger leaves. Plant leaf area and shoot dry mass were both positively correlated to GDDsoil, but inversely correlated to root starch concentration, indicating a link between root carbohydrate reserve mobilisation and shoot growth. Conclusions Warm soils stimulated root starch and N mobilisation, root growth and primary nutrient uptake with further consequences on canopy growth and altered N partitioning among the plant components. Significance of the Study Following winter dormancy, GDDsoil can thus be used to model above- and below-ground plant growth responses in the grapevine.© 2015 Australian Society of Viticulture and Oenology Inc.
- ItemTemporal trends in millet consumption in northern China(Elsevier, 2014-10-01) Atahan, P; Dodson, JR; Li, XQ; Zhou, XY; Chen, L; Barry, LA; Bertuch, FTemporal trends in prehistoric millet consumption are investigated in two regions of northern China, in the Wei River valley and a northern zone that encompasses north-eastern Shaanxi, western Shanxi and south-central Inner Mongolia. By directly radiocarbon dating each sample investigated, inferences about the timing of dietary shifts inferred from stable carbon and nitrogen isotope compositions can be made with a high degree of precision. Evidence presented here indicates that humans living around 4000 years ago in both the Wei River valley and the northern zone were heavily dependent on millet for their subsistence. By ca. 2500 cal. yr BP, a major diversification of diet had occurred in the Wei River valley, with some consuming much larger proportions of C3 foods than previously. These C3 foods may have included the western-derived cereals – wheat, barley and oats – and also rice. © 2014, Elsevier Ltd.
- ItemUsing stable isotope analysis of archaeological pandanus nutshell to understand past rainfall at Madjedbebe, northern Australia(Australian Nuclear Science and Technology Organisation, 2021-11-17) Florin, A; Roberts, P; Marwick, B; Patton, NR; Schilmeister, J; Lovelock, CE; Barry, LA; Hua, Q; Nango, M; Djandjomerr, D; Fullagar, R; Wallis, LA; Faibairn, AS; Clarkson, CArchaeological research provides a long-term perspective on how humans live with various environmental conditions over tens of thousands of years. However, to do this, archaeologists rely on the existence of local and temporally comparable environmental proxies, which are often not available. Our research at Madjedbebe, a ~65,000-year-old archaeological site on Mirarr country in northern Australia, developed an on-site proxy for past rainfall from pandanus nutshell, a remnant of ancient meals eaten at the site. This talk will discuss how we can use ancient food scraps, such as pandanus nutshell, to document past rainfall and what the results of this research mean for communities living at Madjedbebe in the past.
- ItemYou are what you eat. Examination of isotopes in determining plastic ingestion by fish(University of New South Wales and Australian Nuclear Science and Technology Organisation, 2015-07-10) Wilson, S; Mazumder, D; Jacobsen, GE; Barry, LANot provided to ANSTO Library.