Environmental Geology & Geochemistry

Assess impact of marine waste disposal

Studies of impact by coastal cities on continental margins have shown that by using specialist techniques it has been possible to determine that sediments in the immediate vicinity of large cities (Newcastle, Sydney and Wollongong) are contaminated by heavy metals and that each city has a particular signature of metal mixtures. However, under conditions of high-energy, natural processes has effectively dispersed substantial contaminant loads from the continental margins of New South Wales. For more information contact A/Prof. Gavin Birch.

Port Jackson 1

Estuarine processes and development of a contaminant model for complex mixed/stratified estuaries

Sediments and associated contaminants are trapped in well-mixed estuaries, but largely bypass stratified estuaries under high-precipitation conditions. This challenging research requires coupling of chemical and hydrodynamic models to describe processes controlling supply, dispersion and accumulation of toxic heavy metals in these complex estuaries. For more information contact A/Prof. Gavin Birch.

Sediment toxicity

This large, ongoing research programme involving several Australian and international organizations, is assessing sediment quality guidelines for use in Australia and determining sediment toxicity in Port Jackson using a comprehensive array of chemical, ecotoxicological and biological tests. This is the largest study of its kind outside the United States and is the first such assessment of the guidelines. Current research in this area is to measure directly the proportion of contaminants available to biological systems using a unique fugacity approach and to assess the effects of contaminants on target organisms. For more information contact A/Prof. Gavin Birch.

Effective remediation of stormwater, re-cycling and water harvesting

This study has revealed that remediation devices currently being deployed to improve stormwater quality mainly remove gross pollutants and are generally inefficient at removing particle-bound contaminants. Waste materials are being tested in the remediation process and an experimental stormwater device is being used to remediate contaminated stormwater to produce clean, harvested water for irrigation and possibly domestic use in a highly urbanized catchment. For more information contact A/Prof. Gavin Birch.

Regional contaminant framework

Heavy metals are being used to establish a contaminant framework for 38 estuaries on the central NSW coast. This data base is the largest of its kind in Australia and amongst the most extensive globally. The data set is being used to establish a contaminant/sediment indicator for estuarine health assessment. For more information contact A/Prof. Gavin Birch.

River Bank Stability and Channel Change

River Bank Stability study site

Recent research by A/Prof Tom Hubble has included several studies into the relationships between flooding, tree-clearing, bank failure, sand extraction and stream erosion. They have focused on the Hawkesbury-Nepean River system which is one of the most comprehensively studied coastal rivers in New South Wales. One important finding was the demonstration of a causal link between riverside tree clearing and large-scale bank failure which showed that river banks covered with a healthy riverside forest are more resistant to bank-failure and stream erosion during floods than banks whose forests had been removed.

Tree Roots, Weirs and Sand Extraction

Follow-up studies to those focusing on river bank stability have examined the extent to which roots reinforce river-bank soils and that they act in a similar way to steel mesh used to reinforce concrete. Tree roots bind the soil together into a more cohesive mass and the tensile strength of the roots increases the cohesive strength of the soil mass, making it more resistant to mass failure. Other studies, led by A/Prof Tom Hubble, have examined the strength and distribution of the roots of some common riverside trees, the role of weir construction in promoting the erosion of river-banks, and the channel changes resulting from bank and channel sand extraction.