Research student profile: Adrienne Ryan
The ecological impact of dust emitted from Cowal Gold Mine (CGM).
The aim of my project is twofold. The first intent is to identify and determine the likely provenance of an aeolian component in the topsoil surrounding Cowal Gold Mine (CGM); the second is to then assess the likely current and future ecological impact of these aeolian materials, as well as any alteration to pedological processes and properties.
The open cut CGM is located in an environmentally sensitive area; its eastern flank protrudes across the high water level of Lake Cowal, a wetland of national significance. Dust is inevitably generated at CGM, and is likely to be enriched in heavy metals liberated from the ore body.
Current reporting on dust emissions at Cowal Gold Mine is tacitly benchmarked to the National Environment Protection Council (NEPC) Guidelines on the Investigation Levels for Soil and Groundwater. These guidelines are intended for urban soils and moreover are confessed as being somewhat arbitrary. There is a need for local or site-specific eco-toxicological data that relates to land use.
Furthermore whilst ancient deposition of aeolian dust is known to have been an active factor in the process of soil formation and landscape evolution in south-eastern Australia, the role of contemporary and anthropic dust is less well understood.
To best understand the role of the mine in as a dust point source, I have taken soil samples on a number of transects extending from the mining bund. I wanted to encompass areas under the prevailing wind across the mine as well as occasional wind receiving (and therefore potentially dust receiving) areas. It follows that this sampling system should allow for the characterisation of local soils in both a ‘pristine state’ and in likely dust-affected areas.
Most of my analyses use the likely aeolian component, fractionated from the bulk soil material based on particle size. High resolution particle size analysis will enable me to infer a likely transport distance and therefore source for the dust particles. Mineralogy (XRD) and elemental composition (ICP-MS) are a key part of the analyses – a comparison of the geochemistry of topsoil and subsoil samples will indicate whether a contemporary aeolian accession is implicit. This data will then be rationalised with geochemical composition of captured dust samples.
To better understand the pedological role of these recent aeolian deposits, I’ve also had thin sections of topsoil prepared, and will study their micromorphological features using the scanning electron microscope (SEM) and a petrographic microscope.
Two plant species sampled in similar transects to the soil have been analysed for total metals (ICP-AES), and this sampling will be replicated in each year of my project. I also intend to investigate soil microbial activity.
The successful completion of this project will hopefully enhance the understanding of both the distribution and the impact of mine dust deposition in the ecologically-sensitive area immediately surrounding CGM. This will include the potential modification of surface soil physical and chemical characteristics, as well as possible toxicological effects.
Findings from this work may potentially benefit not only the ecosystem surrounding CGM, but also those ecosystems adjoining mines elsewhere in rural and regional Australia with significant dust issues. Ideally this work will contribute towards the generation of appropriate EIL’s for soil in rural and ecologically sensitive areas.
I grew up on the south west slopes of NSW, completed my Bachelor of Science in Agriculture (Hons I) at The University of Sydney in 2005, traipsed about overseas for a couple of years and somehow found my way back to Sydney to start my PhD last year.
I have been granted an Australian Postgraduate Award (APA) and a FAFNR top-up scholarship.
In the first year of my candidature I was lucky enough to travel to China to attend the International Congress on Soil Micromorphology, where I presented a paper and also received the IUSS Commission 1.1: “Young Micromorphologist’s Publication Award.”
During my undergraduate degree I was the fortunate recipient of the Samuel McCaughey Institute Undergraduate Merit Scholarship. I also achieved a place on the Deans List of Excellence in Academic Performance in three of my four undergraduate years. Between the second and third years of my degree I received a summer Scholarship from CSIRO Land and Water and the Rice CRC and spent three months in Griffith completing a studentship.
- A.L. Ryan and S.R. Cattle, 2006. Do sand dunes of the lower Lachlan floodplain contain the same dust that produced parna? Australian Journal of Soil Research, 44, 769-781