- Title
- Distribution of heavy metals in the sediments of the Gippsland Lakes, Victoria, Australia : implications for management
- Creator
- Trewarn, Adam
- Date
- 2023
- Type
- Text; Thesis; PhD
- Identifier
- http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/197194
- Identifier
- vital:18833
- Abstract
- Sediments are the ultimate repository of most contaminants that enter Australia's waterways; therefore, it is appropriate that regulatory attention addresses the risks posed by sediment contaminants. The release of elevated levels of heavy metals into the environment is a common by-product of our industrialised way of life. This problem continues to increase throughout the industrial age. We are now only beginning to understand the actual long-term burden that must be managed. Globally, estuaries are a critical focal point for civilisation and development. Owing to their strategic location and abundant resources, they have been utilised as trade hubs and industrial centres, and are often subject to intense industrial and urban development. Because estuaries accommodate large volumes of fine-grained sediments, their capacity to trap and absorb metal pollutants qualifies them as important sinks and receptacles for terrestrial, atmospheric, and oceanic metal input. Estuaries also provide important environmental services. Their protective conditions harbour a diverse range of biota, and the biogeochemical processes they accommodate play a key role in nutrient cycling and metal sequestration. However, contamination of estuaries with heavy metals is an ongoing issue, particularly as they bioaccumulate and transfer from sediments to aquatic organisms through the food chain. The Gippsland Lakes catchment has a 150-year history of a range of industrial activities, including gold and other metal mining, large open-cut brown coal mines and associated coalfired power stations, powering much of the state of Victoria, plantation forests and associated timber and paper mills, and extensive agriculture, including intensive dairy. Many of these activities are potential sources of contamination, particularly in bygone times, when environmental awareness and sound practices were less prevalent. The issue of highly elevated levels of heavy metal contaminants present within the Gippsland Lake sediments was first identified over 35 years ago. This comprehensive study looks to re-evaluate the modern surface sediments from across the Gippsland Lakes to determine, (i) If previously identified elevated Hg levels are still present or can be replicated (ii) If there are other metal contaminants that may warrant further attention, (iii) If possible, contamination is current, historical or a prolonged event (iv) If there are any natural or anthropogenic influences affecting metal concentrations within the sediments (v) What is the impact of heavy metal pollution across the Gippsland Lakes? Surficial grab and consolidated core sediment samples were collected over a period between 2015-2018 from thirteen defined locations across the Gippsland Lakes, representing the major geomorphological features of the area (e.g. major river mouths and lakes). Total metal analysis, sediment grain size, and XRF high-resolution core scanning provided insight into the overall distribution and possible risks of bulk and heavy metals present in the Gippsland Lakes sediment. Elevated concentrations of Cr, Ni, As, Cu, and Hg were found throughout the study area, exceeding the lower SQG trigger values across multiple depths and locations. Of the numerous metals initially investigated (Cr, Ni, Cu, As, Cd, Hg, and Pb) within the surface and core sediments, the findings of this study reiterated that the greatest concern was the degree of contamination and distribution of elevated levels of Hg in the western regions of the Gippsland Lakes. In addition, it highlighted the risks associated with elevated levels of Cr, Ni, and Cu. Cr and Ni have been identified at elevated levels throughout most of the western locations, Lake Victoria and Lake King, while isolated Cu is present at Paynesville. Further analysis into the metals and the interactions with the environment has defined three separate influences contributing to the elevated concentrations of heavy metals present across the study area, (i) Natural sources and cycling (Cr, Ni, and As): Concentrations of Cr, Ni, and As are likely a result of natural sources from the surrounding catchment, rather than a specific anthropogenically derived source. (i) Diffuse anthropogenic sources (Hg): The calculated pollution indices showed little to no natural influence on Hg concentrations; therefore, Hg concentrations were deemed highly likely a result of diffuse anthropogenic origin. (ii) Point source (Cu): Concentrations of Cu were generally very low throughout the study, except at a single location in an urbanised area adjacent to a commercial boatyard. This project has provided the most recent and comprehensive assessment of the presence, distribution, and leading influences on heavy metals present in the Gippsland Lakes, forming a strong foundation for informed management of the area into the future.; Doctor of Philosophy
- Publisher
- Federation University Australia
- Rights
- All metadata describing materials held in, or linked to, the repository is freely available under a CC0 licence
- Rights
- Copyright Adam Trewarn
- Rights
- Restricted access by author for 24 months starting 15 January 2024
- Subject
- Heavy metals pollution; Heavy metal enrichment; Heavy metal distribution; Estuarine sediments; Environmental Management; Gippsland; X-ray fluorescence; Source apportionment
- Thesis Supervisor
- Reeves, Jessica
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