Fuel Switch Good News For Antarctic
Sydney Morning Herald
Monday July 14, 1997
Australian car owners' switch to unleaded petrol is showing up in Antarctica, where lead levels measured in snow near an Italian base are said to have fallen strikingly.
Particles of the heavy metal may take just one month after leaving an Australian exhaust pipe to reach the polar ice cap, an Italian study showed yesterday.
Snow cores taken around the Terra Nova Bay station show that from a 1986-7 peak of eight picograms - or million-millionths of a gram - the lead levels fell to about two picograms a gram in the early 1990s. This brought the levels back to par with those of the early 1960s.
Lead reduction began in Australia in the early 1970s, but it was not until 1986 that new cars were required to run on unleaded petrol, according to the Federal Environment Protection Agency.
In an automotive industry policing statement last month, the Prime Minister, Mr Howard, said leaded fuel would be phased out by 2010.
Dr Carlo Brabante, of the University of Venice, told an international symposium on Antarctica and Climate Change in Hobart that lead consumption in petrol for Australian cars peaked at more than 6,000 tonnes a year about 1985.
About 75 per cent of the metal used in leaded petrol was transmitted quickly to the troposphere, the lower level of Earth's atmosphere. Some lead was then transported to the poles and deposited.
"What comes out of the exhaust in Australia can be seen next month in Antarctica," he said.
Using ultra-clean equipment and electro-chemical techniques, the Italian scientists chose three measuring sites around their station, on the eastern coast of the Ross Sea, to recover snow dateable for 30 years.
They found a natural contribution of lead in Antarctic snow at about 0.25 picograms a gram, but an average level of 5.2 picograms at their sites, indicating that up to five picograms had come from human origin.
By taking 12-metre-deep snow cores and digging trenches, they traced the rise of lead deposition through the oil crisis of the early 1970s to recent years.
Their findings echo strongly those of British Antarctic Survey scientists who found a similar decline near Halley station on the Weddell Sea. But this began 10 years earlier in 1975, coinciding with the introduction of alcohol-based fuel in Brazil.
The symposium also heard predictions that the widely reported disintegration of the Larsen Ice Shelf on the Antarctic Peninsula would worsen if local air temperatures
continued to warm.
About one-third of the northern section of the shelf, or 5,600 square kilometres, was lost in 10 years to last March, according to Professor Helmut Rott, of the University of Innsbruck.
"The warm period of (recent) decades has been a unique event during at least several centuries," he said.
© 1997 Sydney Morning Herald