Gavin Birch - Geosciences
Gavin Birch is an associate professor in Geosciences at the University of Sydney, and initiator of the Environmental Geology course. He has worked at the University of Cape Town and Esso/Exxon Corporation.
Managing toxic wastes in waterways
Professor Birch’s research focuses on the source, fate and effects of contaminants in marine, estuarine and fluvial environments, as well as policy solutions for remediation and recycling. Within these fields, he is involved in a wide range of projects.
In the area of marine waste disposal, Birch has shown that it is better to discharge city waste to high-energy areas of the coastal shelf, where natural processes disperse a substantial proportion of the contaminant, considerably reducing adverse biological effects.
One of his research programs assesses sediment toxicity using a comprehensive array of chemical, ecotoxicological and biological tools. Current results suggest that guidelines may be overprotective. The goal is to provide more subtle and earlier warning of possible biological change, thus preventing damage before it occurs.
A contaminant model to cover complex estuaries is in development. Birch has found that toxic sediments and associated contaminants are trapped in well-mixed estuaries, but largely bypass stratified estuaries. Contaminants discharged under high-precipitation conditions may therefore not require remediation, reducing clean-up costs for harbour managers.
Remediation devices currently deployed to improve stormwater quality are much more effective at removing gross pollutants than particle-bound toxicants. Birch is testing the viability of waste materials in the remediation of contaminated stormwater with the overall aim of converting waste material into a valuable product.
Sedimentary heavy metals are being used to develop a robust and cheap contaminant/ sediment indicator to assess estuarine health. This indicator scheme is being applied to 38 estuaries to provide a contaminant framework for the NSW coast. The database will solve the problem of how to assess and rank estuarine health, to make more efficient use of limited resources.