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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

Citation

Proemse, B and Gadd, P and Zawadzki, A and Maxwell, C and Barmuta, L, Tracing water quality changes in water level manipulated lakes in central Tasmania using high resolution core scanning and isotopic dating techniques, Abstracts for the Australian Society for Limnology Conference 2017, 24-28 September, Sydney, pp. #52. (2017) [Conference Extract]


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Abstract

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.

Item Details

Item Type:Conference Extract
Keywords:lake, sediment, water quality
Research Division:Earth Sciences
Research Group:Geochemistry
Research Field:Inorganic Geochemistry
Objective Division:Environment
Objective Group:Physical and Chemical Conditions of Water
Objective Field:Physical and Chemical Conditions of Water in Fresh, Ground and Surface Water Environments (excl. Urban and Industrial Use)
Author:Proemse, B (Dr Bernadette Proemse)
Author:Barmuta, L (Associate Professor Leon Barmuta)
ID Code:121677
Year Published:2017
Deposited By:Zoology
Deposited On:2017-10-10
Last Modified:2017-10-10
Downloads:0

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