Earth's sunscreen – the ozone layer
Box 4 | Australia finds a replacement for methyl bromide
For years, horticulturalists have been using methyl bromide to sterilise soil. But with the knowledge that it is an ozone-depleting substance, it is becoming imperative to find alternatives.
Unlike chlorofluorocarbons (CFCs), methyl bromide gets into the atmosphere naturally – particularly in volcanic eruptions – but human activity is probably responsible for releasing much more. Molecule for molecule, it is actually a more efficient ozone-killer than the CFCs, but it breaks down faster than they do.
The Montreal Protocol set out controls for the use of methyl bromide, and in 1997, it was agreed that developed countries would discontue their use of methyl bromide by 2005, and developing countries to cut their production by 20% of their 1995-1998 usage by 2005, with complete phase out of methyl bromide by 2015. By 2009, the global production of methyl bromide controlled under the Montreal Protocol had decreased to 13% of the 1991 amount.
Dr Jonathan Banks, a researcher in CSIRO’s Stored Grain Research Laboratory at the Division of Entomology, has been at the forefront of finding ways to avoid using methyl bromide. For example, covering an area of ground with plastic and then waiting for the sun to heat it up is quite an effective way to sterilise soil. If the temperature is carefully monitored, there’s even a bonus: it is possible to kill the harmful bugs without affecting many of the good ones!
Fumigation of produce can also be carried out using other chemicals – for example, carbon dioxide – and a whole suite of different methods can be used to manage pest infestations.
In recognition of his work, Dr Banks received the 1996 Stratospheric Ozone Protection Award from the US Environmental Protection Agency.
Boxes
Box 1. Meet the ultraviolet family
Box 2. Can plants get sunburn?
Box 3. How ozone is lost
Related sites
CSIRO researcher wins ozone award
More about the U.S. EPA Montreal Protocol Awards
Page updated February 2006.