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Ships leave air pollution in their wake

Container ship

Shipping is still the most greenhouse friendly and fuel efficient way of moving freight(Source: dan_prat/iStockphoto)


"These [non-greenhouse gases] produce photochemical smog and airborne particulates that can contribute to health issues," says study lead author Dr Laurie Goldsworthy from the Australian Maritime College.

"There are pulmonary and cardiovascular concerns and they also change atmospheric chemical processes causing things like acid rain."

Ports in Perth, Melbourne, Sydney and Brisbane are located where seasonally-prevailling onshore winds dominate and pollutants from shipping are carried into the air-sheds of these major urban population centres.

Goldsworthy and study co-author, Dr Ian Galbally from CSIRO Marine and Atmospheric Research say methods used to estimate coastal and in-port shipping emissions need to be updated, as does how their impact on human health is assessed.

They measured the emission levels of a coastal cement carrier MV Goliath sailing between Devonport in Tasmania to Melbourne.

Then they calculated exhaust emission data from different types of vessels docking at Australian ports, comparing different fuels, running speeds and engine designs.

"The levels of emissions from ships were surprising," says Goldsworthy.

"We didn't think ships would be such significant contributors."

Many ships visiting Australia use cheap fuels derived from the residue of the crude oil refining process. These residue oils are likely to have a higher sulphur content than the global average.

"The United States, Canada and the Baltic and North Sea ports of Europe have imposed restrictions on fuel sulphur content," says Goldsworthy.

'We need to do more studies here to determine whether we need similar regulations."

Big business

The research, in the journal Air Quality and Climate Change, says over 753 million tonnes of international exports pass through Australian ports annually, making up a tenth of global shipping.

The researchers say shipping is the most greenhouse-friendly fuel-efficient way of moving freight.

"Changing fuels will produce less emissions, but increase costs, which has an economic impact," says Galbally.

The scientists want further research on the impact of sulphur and nitrogen oxide on the atmosphere across remote higher latitude regions of the southern hemisphere.

Galbally says these compounds ultimately become involved in cloud formation and atmospheric photochemistry.

"I previously looked out over the oceans and thought this is clean pristine air," says Galbally.

"It last saw land over South Africa or South America and has travelled 10,000 kilometres to get here."

"I've now have to rethink that, there are many ships traversing that ocean introducing pollutants into the air."

Tags: transport, air-pollution, engineering, sea-transport