compiled by Barbara Goldflam
Searching
for oil and gas on Australia’s North West Shelf using a perspex tank full
of honey, putty, sand and cake sprinkles may seem a little bizarre, but University
of WA geologist Dr. Myra Keep believes it may help us locate where oil fields
may or may not be.
The northern margin of Australia is located on a major geologic boundary, with Australia on the south side currently colliding with Indonesia on the north side. As the two collide, continental-scale stresses are generated, which affect all of the existing geological structures on the North West Shelf, including those that host oil and gas. Although these stresses and the processes that create them are broadly understood, it’s the fine detail of where the stresses go and how they affect the oil fields that Dr. Keep is trying find.
In her laboratory at UWA, she creates geological models of Australia and Indonesia colliding, using alternating layers of a special silicon putty, sand, and castor sugar, all floating in a perspex tank full of honey. Motors attached to perspex plates in the tank can push the putty layers around in different directions, to see how they collide, what geological structures they generate, and where the stresses go. Cake sprinkles covering the surface of the model are used as marker points, to track which bits of the model are moving where at any point during the model sequence. Models usually take two to three days to prepare, and 8 to 10 hours to run.
The results of the models are used in conjunction with subsurface data from the offshore oil and gas fields, to see how the models compare to real life. Dr. Keep hopes that these experiments will help to predict which areas have been highly affected by stresses, and which areas have been only mildly affected. In some cases the stresses help to create oil and gas traps, and in other areas they cause potential oil traps to be dry. She believes that the processes she is discovering in her laboratory will help to enhance exploration efforts on the North West Shelf.
Amanda Tilbury was recently awarded the Undergraduate Water Prize by the Australian Water and Wastewater Association for her ground-breaking work in isolating AT2, a bacterium which may be the solution to cleaning up herbicide contaminated groundwater that occurs on the Swan Coastal Plain.
The plume, contaminated with the herbicide atrazine, is about 300 m long and continues to spread, threatening the environment and may pose health risks. The frequent use of chemicals such as pesticides has resulted in widespread contamination of our environment. The herbicide atrazine is the most extensively used world-wide, and is also the most commonly found herbicide contaminating groundwater. The bacterium, which was isolated from the contaminated site, breaks down atrazine to carbon dioxide and is set to be released into the environment to clean the contamination this year.
The use of microorganisms in the decontamination process is known as bioremediation and has attracted increasing attention over the past few years. Perceptions are that bacteria are dangerous, but less than 1% cause disease. Pseudomonas sp. strain ADP, the first bacterium known to mineralise atrazine, was imported into Western Australia for research into its potential use for the bioremediation of the contaminated groundwater. It was discovered at an atrazine contaminated site in the USA. The discovery of Pseudomonas sp strain ADP has allowed extensive research into the mineralisation of atrazine and the cloning and sequencing of the genes that mediate atrazine metabolism. Pseudomonas sp. strain ADP is patented and its use in Australia is restricted by quarantine regulations. These impediments to its widespread use initiated the search for locally occurring atrazine degrading microorganisms.
An atrazine-mineralising bacterium was successfully isolated from atrazine-contaminated groundwater in Perth. It was also identified as a Pseudomonas sp, (denoted AT2) and is not pathogenic to humans, animals or plants. The half life of atrazine in the presence of Pseudomonas sp. strain AT2 was reduced from between 1-8 years to 5.48 hours. Another advantage of strain AT2 is that atrazine degradation was more reliable in our laboratory than strain ADP.
A further advantage of strain AT2 is that it is indigenous to the contaminated site and is therefore more likely to survive any environmental challenges encountered at the site. Furthermore, strain AT2 is not patented and because it was isolated from Australian soil, has no quarantine restrictions and is available for use throughout Australia. It has also been requested by the NSW Department of Agriculture for use on atrazine contaminated soils before atrazine sensitive crops are planted.
Many European countries, including Germany, Italy, Norway and Sweden have banned the use of atrazine due to frequent detection of high concentrations of atrazine in groundwater. Although atrazine is important to Australian industry, it is currently under review by the National Registration Authority due to its persistence in the environment and toxicity to aquatic ecosystems. An estimated few thousand tonnes per annum are used in Australia and there would be serious consequences on the agricultural industry if atrazine was withdrawn.
The discovery will significantly improve the quality of our aquatic eco-systems. With proper application of the locally occurring bacterium, the presence of the herbicide atrazine in our waterways will be drastically reduced in the future.