Investigations
Biomonitoring - assessing contamination of organisms
Illegal disposal of tributyltin
Contamination of edible animals
Acid sulfate drainage from soils
Gathering evidence for license compliance and enforcement action under the Environmental Protection Act often involves the design and conduct of scientifically robust studies of environmental harm, such as contamination of waterways and consequent harm to plants and animals. A number of methods are used for this work, including assessment of contamination of sediments and organisms within waterways which have been exposed to impacts from undesirable practices such as the release of unauthorised discharges.
Investigation can involve a range of techniques (e.g. sediment sampling) in a range of environments (e.g. sampling drainways) to find the sources of contamination (e.g. oil contamination via a stormwater drain).
Biomonitoring - assessing contamination of organisms
'Biomonitoring' means the use of living organisms (plants or animals) as indicators of ecological health and/or the presence of contamination.
The presence or absence of plant and animal species, or their abundance relative to what is expected at a "healthy" location can be used as an indication of ecological health. At impacted sites some of the more tolerant species may dominate, and less tolerant species may be absent.
The QEPA is currently working with a University of Queensland research team to develop a system for assessing the ecological health of Queensland estuaries based on measurements of communities of benthic (bottom dwelling) organisms present.
Where contaminants are present, these can often be identified and quantified by chemical analysis of samples of plants and animals from that location. This kind of biomonitoring has three important advantages over simply analysing water and sediments for the presence of contaminants. The first advantage is that many organisms accumulate contaminants, making them easier to detect and measure. The second advantage is that the presence of contaminants in the tissues of plants and animals is irrefutable evidence that the environmental contaminants are present in a form which organisms can absorb. The third advantage is that sampling of only water and sediment may fail to detect intermittent releases of contamination, whereas plants and animals that are resident in the area of interest tend to accumulate and retain the evidence.
Animals currently used by the QEPA to detect and quantify contaminants in Queensland estuaries include:
| Typha (bulrushes) which are useful accumulators of metals and other contaminants. | Oysters deployed in bags (such as those shown below) can be used as sentinel organisms in environments where they are not naturally growing. |
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Crabs, such as Uca coarctata (left) and Heloecius cordiformis (right) are common crab species used as "sentinel organisms" to detect and quantify contaminants in Queensland estuaries. |
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Some investigations (previous and current) by Waterways Scientific Services:
Illegal disposal of tributyltin (TBT)
 Oysters were deployed in bags to determine whether TBT was present and available to organisms. |
Tributyltin (TBT) is a tin-based organic compound commonly used in antifouling paint for marine ships. TBT compounds are extremely toxic to marine organisms (click here for more information). In addition to the problem associated with the leaching of TBT from ship hulls, the inappropriate disposal of TBT-containing paint stripped from ship hulls during repairs and repainting is a potential source of environmental harm. Regulations for the disposal of this material require that it be disposed of responsibly, for example by burial in a secure landfill. During 1998/99 the QEPA suspected unacceptable practices, and investigations were conducted into contamination related to these practices. In addition to sampling of waters and sediments suspected of being contaminated by TBT, the QEPA depolyed oysters and mussels from uncontaminated locations in mesh bags near sites of potential contamination. These animals were found to accumulate TBT from the affected waters. This provided evidence that active contamination leading to environmental harm was occurring, and the persons responsible were prosecuted |
Contamination of edible animals near Runaway Bay?
The QEPA is involved in surveys of contaminants in edible organisms (e.g. crabs and oysters) living in canals near a former landfill site at Runaway Bay for the Gold Coast City Council. This work is designed to check for evidence of leaching of metals or pesticides into the waters of the canal, and which might be accumulating in aquatic animals.
Results from work done in 1998 showed that although there were traces of residual pesticides and other contaminants commonly found in urban waterways, these were less than or similar to those at reference sites well away from the former landfill. In addition the levels of contamination of the tested animals were generally well within national standards for human consumption.
Are these oysters safe to eat? |
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Further investigations done in 1999/2000 included additional sites and also examined whether oysters within the canal areas were free from human disease organisms. The results were similar to those in 1998, and showed that the most significant risk associated with consumption of catches from residential canals was that of bacteriological contamination in oysters.
Acid sulfate drainage from soils near Brisbane creeks?
During 1996 and 1997 continuous automated monitoring of pH was conducted for an extended period in several creeks near Brisbane Airport and Nudgee Beach, where unfounded allegations were made during 1996 and 1997 of a "catastrophic die-off" of marine organisms. Potential acid sulfate soils underlie much of the area concerned, and this study was designed to detect any acid runoff events which might have had harmful effects on aquatic organisms in the area. The state-of-the-art equipment used enabled the monitoring of pH on a 24 hours per day, seven days a week basis. This is in contrast to what could be achieved by merely visiting sites on a periodic basis, an approach which can easily miss episodic events, for example acid run-off which only occurs after a rainstorm.
The data show that no acid drainage incidents occurred in any of the creeks concerned. Monitoring was conducted for a period of several months in each of several creeks and included a range of weather patterns including severe storm events.
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In several creeks, pH meters were deployed for several months at a time. to determine whether acid drainage was occurring.
Last updated: 28 November 2003