AUSTRALIA'S top scientific body has cast new doubt over claims Gladstone Harbour is being severely damaged by dredging.
The CSIRO released a report yesterday, which found levels of dissolved metals had not increased in areas where dredging is being done.
The report's author, Dr Simon Apte, said dissolved metals in the harbour were "not an issue at present."
Gladstone Ports Corporation paid for the survey to be conducted. While that fact is sure to cause community doubt over the report's independence, the high credibility of CSIRO will lend significant weight to the pro-dredging argument.
"The good news is that all those metals we monitored were below the levels of concern," Dr Apte said.
Dr Apte said he said concentrations of aluminium exceeded 'environmental concern level', that definition "doesn't imply that the levels are unsafe".
Although the report finds nickel and copper concentrations have increased in some parts of the harbour, those are not areas where dredging is taking place.
"There are natural sources of nickel and copper in the harbour," he said.
"There is no suggestion that dredging was contributing to levels of copper and nickel."
"If that was the case, we would expect to find the highest areas of concentration around the dredging, which would imply dredging is the source of it."
"We found no evidence of that."
The report found "elevated" levels of arsenic in some sediment in Gladstone Harbour.
Asked to clarify that finding, Dr Apte said the arsenic levels were in line with previous historical levels in Gladstone Harbour and they were "elevated" in comparison with other harbours.
He said the arsenic levels detected were of no concern for human or wildlife health.
The Port Curtis water and sediment survey 2011
- Gladstone Ports Corporation paid for CSIRO to conduct the independent testing.
- The survey was largely similar to one carried out in Gladstone Harbour in 2004/5. Testing was carried out at 21 sites around the harbour.
The report found:
- No evidence of increased dissolved metal concentrations in the areas of Port Curtis that are being dredged.
- The concentrations of dissolved arsenic, cadmium, cobalt, chromium, copper, manganese, nickel, lead and zinc were below the ANZECC/ARMCANZ marine water quality guideline trigger values that apply in Australia at all 21 sites sampled and the concentrations were relatively low compared to other industrialised harbours.
- Dissolved aluminium concentrations were above the ANZECC/ARMCANZ (2000) environmental concern level (ECL) of 0.5 µg/L at the majority of sites sampled. It should be noted that there is no reliable guideline value for aluminium in marine waters in Australia and the ECL value is a highly conservative value based on very limited toxicity data. There are no water quality guidelines that apply for aluminium in marine waters in Europe or North America. From the current data set, it was not possible to attribute a specific source of the dissolved aluminium.
- Dissolved copper and nickel concentrations were higher in December 2011 compared to previous CSIRO surveys in 2004/5.
- Total metal concentrations in the seafloor sediment samples were below ANZECC guideline values for all metals (where guidelines apply) apart from arsenic.
- Few identifiable trends in concentrations across the Harbour, which means that no hot spots of high metal concentrations were found.
- Metals in suspended sediments were not elevated.