The Australian Institute of Marine Science (AIMS) and Australia’s Nuclear Science and Technology Organisation (ANSTO) have begun an investigation to explore the risk of radioactive materials accumulating in marine organisms following the decommissioning of offshore oil and gas infrastructure.
“The experiment will help operators and regulators understand the environmental risk of infrastructure like pipelines with residual levels of NORM (Naturally Occurring Radioactive Material), helping to guide decision-making around whether this infrastructure should be removed or safely left in the ocean,” said AIMS Researcher and experiment lead, Darren Koppel.
According to AIMS, naturally occurring radioactive elements in soils, rocks, the seabed can be accumulated in infrastructure like pipelines. The resultant accumulated NORM that can build up may be present in structures and, if left in the ocean following decommissioning, may eventually leach into seawater before being released into sediments on the ocean floor. This could have an impact on marine organisms.
Currently, there is little data available which describes at what levels NORM from the industry becomes dangerous to marine organisms, a problem the experiment is looking to remedy.
Experiment method
Using facilities in the National Sea Simulator at AIMS’ Townsville headquarters, scientists have dosed marine sediments collected at the AIMS jetty and beach with specific amounts of NORM, and then placed the organisms in the sediments to determine concentrations above which the organisms may start experiencing harm.
The team also extracted eDNA from the sediments to understand and characterise the bacteria biodiversity, and to see whether the radioactivity brought about a change in the bacterial community over the course of the four-week experiment.
“The default position in Australia is that all offshore oil and gas infrastructure must be removed from the ocean when it is no longer being used,” remarked Koppel. “But leaving infrastructure in-situ may be allowed if the oil and gas operator can demonstrate this will result in an equal or better environmental outcome than removing it, that any environmental risks and impacts will be acceptable, and leaving it will comply with Australia’s obligations under international conventions.”
AIMS scientists are also investigating other aspects of the decommissioning question, including the habitat value of offshore structures and whether they can help maintain populations of marine species (including invasive ones and those important for Australian fisheries) by aiding dispersal processes.
