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Southern Cross GeoScience

Honours projects

Southern Cross GeoScience offers the opportunity for students to carry out Honours research projects within our innovative Centre. Students are enrolled with the School of Environment, Science & Engineering.

The following project areas are currently available.

Can landslide-induced iron mobilisation in nutrient-poor alpine streams encourage N-fertilisation by cyanobacteria?

Supervisor - A/Prof Scott Johnston
Recent research in pristine, low-nutrient, Alpine streams in NZ demonstrates that large landslides can enhance formation of Fe(III) rich plaque on stream cobbles. This may have important knock-on consequences for N-cycling by encouraging / enhancing populations of diazatrophic cyanobacteria. This study will explore this process and its potential contribution to N-fertilisation. Funding support available. Field study site, Fiordland, New Zealand.

Controls on riverine air-water CO2 outgassing

Supervisor - Dr Siyue Li
Inland waters have recently been identified as an important source of CO2 to atmosphere. However, there is a latitudinal bias towards northern hemisphere systems on this topic. Furthermore, carbon budgets of inland waters largely include major rivers, which may result in a significant underestimate of CO2 emissions. Lower-order streams draining peatlands and wetlands are known to be an extremely high source of CO2 emission to the atmosphere and are often poorly accounted for in landscape carbon budgets.This project would contribute to that research by investigating the comparative streams of the Richmond River. We will explore the drivers on air-water CO2 outgassing and how this efflux responses to global warming. Field work, lab incubation and mathematic modelling will be used in our project.

Cycles of flood and drought: consequences of fire in acid sulfate soil wetlands for iron mineral transformation and arsenic mobilisation following re-flooding

Supervisor - A/Prof Scott Johnston
During large droughts, fire occurring in ASS wetlands can induce thermal transformation of schwertmannite, a common Fe(III) mineral, to more crystalline Fe(III) phases (ie. hematite). This process can also enhance the environmental availability of certain trace elements (ie. Arsenic). During subsequent re-flooding, reductive bio-mineralisation pathways are influenced by this prior thermal transformation and thus, so are the subsequent mobilisation of trace elements. This study will explore these processes and their consequences for wetland water quality. Funding support available. Laboratory based study

Environmental chemistry of coastal wetlands: Acid sulfate soils, element cycling, water quality and wetland sustainability

Supervisor - Prof Richard Bush
Wetlands are precious ecosystems that our environment relies upon. Wetlands function as massive bio-filters, protecting waterways and enhancing water quality for communities and the broader environment. In Australia, and internationally, these sensitive landscapes are under extreme pressure from land development and human impact. Man-induced drainage and clearing of natural vegetation has dramatically altered wetland hydrology and geochemical function. This project examines a high priority conservation wetland in northern NSW, and involves field studies, advanced field based water chemistry and use of electron microscopy to characterise the geochemical system. This new knowledge will provide a basis for improved wetland care.

Modern environment and issues that constrain access to future energy

Supervisor - Prof Richard Bush
Modern society relies on access to low cost and reliable energy. The supply of these energy needs depends on a global system that combines vast physical infrastructure, complex economic and political relationships, and cutting-edge science and technology. This energy exploitation- consumption system has allowed industrialisation and the growth of a robust global economy, with most of our energy needs coming from hydrocarbons. Yet supplies of these energy resources are finite and importantly the environmental impacts of current energy systems are significant, and in the case of climate change, potentially catastrophic. There is opportunity for an outstanding honours study that addresses society's concerns about the environmental effects of "business as usual" in the hydrocarbon energy sector, and looks for ways to respond to current and future related environmental issues. Large opportunities for innovators and entrepreneurs exist, as will pitfalls for companies that do not adapt to the new business environment. Specific key areas for investigation include environmental impacts of resource exploration and extraction (e.g. dredging and spoil disposal, drilling, transport, unconventional extraction technologies), Environmental pollution (air, soil and water) and waste assessment, reuse and safe disposal

Obsidian sourcing in the Western Mediterranean: study of prehistoric populations

Supervisor - Dr Renaud Joannes-Boyau
The project will entail the geochemical characterisation of archaeological objects made of obsidian (volcanic glass), from Prehistoric sites (5000-4000 BC) located in Corsica, an island south of France. The sourcing results will allow to deepen our understanding of the overall economy of this lithic material, used to make tools and weapons, and thus help the Archaeologists to recover the lifestyles of prehistoric communities.

Phase transformations of bacteriogenic minerals and implications for trace metal mobility

Supervisor - Dr Ellen Moon
Currently researchers in Southern Cross GeoScience are looking at the role of mineral phase transformations on the partitioning of trace metals - for example, when ferrihydrite containing arsenic is heated to 600 C, it transforms to hematite, but what happens to the arsenic? Does it stay in the mineral structure? Does it migrate to the surface? Is it more bioavailable before or after the mineral transformation? In real, natural systems, minerals phases like ferrihydrite are often intermixed with bacteria cells & organic matter - this project will look into how the organic component affects the redistribution of arsenic in these systems. The project will involve wet chemistry (mineral synthesis, As sorption experiments, mineral dissolutions etc.) and analytical work (X-ray diffraction, scanning electron microscopy etc.).

Radiation impact on tooth enamel: Implication for direct dating of fossil remains

Supervisor - Dr Renaud Joannes-Boyau
The project will focus on observing the evolution of the ESR signal of fossil tooth enamel, after X-ray irradiation and thermal treatment. The results will be compared to gamma-irradiation to determine the suitability of X-ray as an irradiation source for dating. A similar experiment will be conduct on alpha irradiation impact, in order to observe the destructiveness of alpha particles onto the enamel crystal.

Relationship between Melaleuca quinquenervia leaf litter decomposition and the behaviour of secondary Fe minerals in acid sulfate soils

Supervisor - Dr Chamindra Vithana
Acid sulfate soils in low lying flood plain areas in northern NSW are dominated by Paper bark (Melaleuca quinquenervia) trees. Studies have found that Melaleuca trees may regulate the groundwater geochemistry and may enhance the oxidation of iron sulfides found beneath the soil surface. Schwertmannite and jarosites are secondary Fe minerals found in these landscapes which form due to partial oxidation of iron sulfide. In those areas schwertmannite is often found as small mineral deposits along the root channels and also as coatings on leaf litter while jarosite occurs as mottles in root channels. Although several studies in the past investigated the behaviour of schwertmannite and jarosite in those areas under prolonged flooded conditions, they disregarded the effect of Melalueca leaf litter decomposition on the behaviour of these minerals and vice versa. This study will focus on understanding the latter process and its influence on regulating the chemical and physical quality of flood water.

Role of algae on 'blackwater' formation during flooding: The relationship between algae in flood water and floodplain vegetation

Supervisor - Dr Chamindra Vithana
'Blackwater' is deoxygenated flood water having a 'black-tea colour due to higher concentrations of dissolved organic carbon (DOC). 'Blackwater' forms when the dissolved oxygen concentration in flood water is depleted at a faster rate than it is replenished during the decomposition of inundated organic matter. Studies have found a relationship between decaying floodplain vegetation and the development of 'blackwater' during flooding season. Some flood plain vegetation types decompose rapidly compared to other vegetation types due to the presence of labile organic matter and therefore, liberate nutrients and organic carbon rapidly to the flood water. Hence, decaying inundated floodplain vegetation can provide nutrients to algae which are common in flood waters. In addition to the decaying inundated vegetation, algae can also contribute to DOC in flood water as they are also rich in labile organic carbon. This study will explore how these different types of flood plain vegetation influence growth of algae in flood water and persistence of 'blackwater' over a longer period.

Role of organic acids on the dynamics of trace elements during flooding events

Supervisor - Dr Girish Choppala
Eastern Australia contains Holocene floodplains with large back swamp basins. Extensive modification of floodplain surface hydrology has taken place with the expansion of agriculture. The hydrological connectivity between backswamp basins and main estuaries has increased, which has led to more frequent flooding. The decomposition of vegetation in flood waters can lead to deoxygenation, and massive fish kills can occur as result of intense deoxygenation. Organic acids that leach from vegetation have a potential to influence trace metal chemistry in riverine sediments. This project will examine the role of organic acids on dynamics of trace metals during inundation.

Seawater on acid: how sea-level rise and tidal inundation influence Fe(III) mineral transformation in acid sulfate soil wetlands

Supervisor - A/Prof Scott Johnston
Acid sulfate soils (ASS) occur in very low lying coastal areas and are at increasing risk of saline tidal inundation. Saline tidal inundation of ASS can increase pH and radically change local geochemical conditions, thereby destabilising important iron minerals. This study will explore how saline inundation will drive the transformation of important Fe(III) minerals and examine the implications for associated trace elements (ie. Arsenic). Funding support available. Local field study site.

Sediment mineralisation induced GHG gas production: Unravelling the dominant controls

Supervisor - Dr Siyue Li
Very few studies focusing in the boreal high-altitude ecosystems highlighted that the contribution of sediment mineralisation to carbon production was dependent upon temperature. The temperature density contrasts with previous carbon-quality-temperature hypothesis, and may not be valid in the Australia due to diverse geochemical characteristics. We hypothesize that the effects of changing temperature and acidification on sediment mineralisation as result of ongoing global warming and Australian ASS (acid sulfate soils) environment may greatly contribute to the future importance of sediment as a source for global occurrence of GHG gas and thus change our fundamental understanding of sediment carbon geochemistry. We will focus on the C production in response to pH, temperature and soil carbon. The project will involve organic carbon, nutrient, pH and DOM fluoresce analyses, as well as greenhouse gas and XRD measurements.

Spatial variability of clay fractions and their influence on heavy metals mobilisation in sulfidic sediment

Supervisor - Dr Girish Choppala
The sediments from Peel Harvey estuary (WA) are dominated with reactive iron monosulfide and nano-particulate pyrite. Our recent results reveal that oxidation of pyrite, a common environmental important mineral is more rapid than expected. This rapid oxidation can have major implications for soil and water health. Clay mineralogy and porosity strongly influences the oxidation of pyrite and related binding mechanisms of heavy metal contaminants. This honours will focus how clay minerals and heavy metals from sulfidic coastal sediments impact the environment.

The surface chemistry of greigite

Supervisor - Dr Ellen Moon
Greigite is an interesting mineral phase in natural systems. It is an iron(II,III) sulfide, and due to the mixed Fe valence, is ferromagnetic. Its role in natural, iron-rich sediments, such as acid sulfate soils, is the subject of extensive research at SCGS. This project would contribute to that research by investigating the surface chemistry of greigite under different conditions relevant to acid sulfate soils. The student will conduct potentiometric titrations and sorption isotherms under varying conditions of pH, ionic strength, temperature etc., and provide valuable data from which our researchers will be able to model the surface electrostatics & sorption mechanisms of greigite. The project will involve wet chemistry (mineral synthesis, sorption experiments, titrations etc.) plus a small component of mathematical modelling.