Browsing by Author "Proemse, BC"
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- ItemReconstructing the history of nutrient loads and sources in the Derwent Estuary, Tasmania, Australia, using isotopic fingerprinting techniques(Springer Nature, 2021-02-24) Stevens, H; Chase, Z; Zawadzki, A; Wong, HKY; Proemse, BCCarbon and nitrogen stable isotope analysis of estuarine sediment cores has proved useful for tracing nutrient sources and for assessing changes to nutrient loading through time. However, this technique has rarely been applied to estuaries in the Southern Hemisphere, despite the vulnerability of urban estuaries to excess nutrient loading and eutrophication because of mounting anthropogenic pressures. This study uses sediment core nutrient concentrations (total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP)) and stable isotope analysis (δ13C, δ15N, and δ34S) in combination with lead-210 (210Pb) dating, to reveal information about past and current nutrient loads and sources to various parts of the Derwent estuary, Tasmania, Australia. The upper estuary was found to experience periods of low dissolved oxygen levels and δ13C and δ15N values indicate that the nutrient sources to the upper estuary are predominantly riverine inputs and pulp and paper mill effluent. The middle estuary was found to have higher nutrient (TN and TP) concentrations than other Australian estuaries (Quibray Bay, Woolooware Bay, and Moreton Bay). Along the whole estuary there was a transition of predominantly terrestrial OM in upper estuary to predominantly marine OM in middle/lower estuary. However, there was a clear influence from a nitrogen source with an enriched δ15N value, likely wastewater treatment plant (WWTP) effluent. 3-endmember mixing analysis between terrestrial OM, marine OM, and WWTP effluent shows that WWTP effluent has contributed to up to 30.9% of sediment composition in the past—highlighting the significance of anthropogenic nutrient inputs, such as waste-water treatment plant effluent, to an urban estuary. © 2021 Coastal and Estuarine Research Federation
- ItemTracing 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, LGreat 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.