Browsing by Author "Barmuta, LA"

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    Identifying the key sources of metal (loid) deposition to remote Tasmanian lakes: is legacy mining a problem?
    (Springer Nature, 0202-03-07) Stevens, H; Barmuta, LA; Chase, Z; Saunders, KM; Zawadzki, A; Gadd, PS; Proemse, BC
    Reports have shown that even remote lakes have been negatively affected by anthropogenic activities. This study used metal concentrations and enrichment factors to comprehensively determine key metal sources and identify potential impacts of recent anthropogenic activity in remote Central Highland Tasmanian (Australia) lakes. Metal concentrations (Al, As, Cd, Cu, Fe, Pb, and Zn) in these lakes remain below Australian interim sediment quality guidelines but have been slowly increasing since the start of the twentieth century. This increase is likely related to increasing organic matter content, rather than any direct, increased input of metals. The largest anthropogenic impact to these systems was damming, which typically led to an increase in organic matter content either directly, by the trapping of particles and nutrients, or indirectly, by stimulating primary production in the lake. This increased organic matter content, in turn, increased the retention of metals, manifesting as an increase to measured metal concentrations. Minor impacts are the historical use of lead shot, leaded petrol, and industrial processes, which may have contributed to the higher Pb enrichment, compared to the other studied metals, in these lakes. Despite recent concerns of metal contamination in the Tasmanian Wilderness World Heritage Area from distant mining activities, there is no strong evidence in this study indicating that lakes in the Central Highlands (a similar distance away) have been impacted by long-distance atmospheric deposition. This is likely related to the decreased rainfall, and thus decreased rates of wet deposition of aerosols in the east of Tasmania, compared to that of the west and in the Tasmanian Wilderness World Heritage Area. © The Author(s) 2024. - Open Access - This article is licensed under a Creative Commons Attribution 4.0 International License
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    Tracing water quality changes in water level manipulated lakes in central Tasmania using high resolution core scanning and isotopic dating techniques
    (Australian Society for Limnology, 2017-09-24) Proemse, BC; Gadd, PS; Zawadzki, A; Maxwell, C; Barmuta, LA
    Great Lake and Woods Lake, located on the Central Plateau of Tasmania, are shallow lakes that are water level manipulated by Hydro Tasmania for power generation and irrigation supply. This has led to concerns regarding the ecological stability of these lakes under varying water levels. Hydro Tasmania has been maintaining and recording lake levels since their damming in the early and mid 1900s: Water level measurements for Great Lake exist since 1916, and for Woods Lake since 1968. These unique long-term water level records show that both lakes underwent significant water level fluctuations over the past few decades. In this project we reconstructed the history of sedimentation during the past 150 years to investigate changes in nutrient fluxes since and prior to damming of the lakes in the early 1900s, using 210Pb dating techniques and high resolution X-ray Fluorescence core scanning (ITRAX). Most lakes in Tasmania are not suitable to investigate recent (<150 years) changes in environmental conditions due to extremely low sedimentation rates. However, the damming of Woods Lake and Great Lake has caused significant increases in sedimentation rates, making them also suitable for investigating changes in atmospheric deposition of anthropogenic pollutants. Our results suggest that water level changes due to water level manipulation since the damming of the lakes have not significantly affected the ecological functioning of the lakes, but the damming itself increased sedimentation rates and burial rates of nutrients (nitrogen, phosphorus). 210Pb dating has also revealed that sediment resuspension does not occur to a depth >1 cm, even at times of low lake levels. Comparison of sediment core proxies (e.g. for water temperature) with 3 decades of water column data demonstrates the limitations of such proxies for paleoclimatology.