ENVIRONMENTAL scientists struggling to return Antarctica to its former
pristine glory are finding the job even harder than they expected.
After a century of rubbish dumping by explorers and researchers, over 70
waste tips litter the Antarctic. So in 1998, around 30 countries that work in
the Antarctic agreed the Madrid Protocol, to clean up the dumps and protect the
environment.
To dispose of the waste on site would mean importing huge amounts of
polluting fuel and equipment. So the original plan was simply to scoop up the
rubbish and ship it out. However, one attempt to move material from the Thala
Valley tip near Australia鈥檚 Casey station made the problem worse by flushing
heavy metals into the ocean.
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Australian researchers drawing up plans for a second crack at the problem
believe the toxic metals in the run-off water from the dumps are bound to tiny
waterborne particles. During the last Antarctic summer, Kathy Northcott of the
University of Melbourne and Ian Snape of the Australian Antarctic Division in
Kingston, Tasmania, tested different ways to filter out the metal-laden
particles from the run-off.
First they tried flocculants鈥攃hemicals that should make the small
particles bind together into clumps large enough to be removed by a filter. But
the only one that worked was a synthetic, cationic (positively charged)
flocculant belonging to a group of chemicals that is known to be toxic to marine
animals. 鈥淭hey clog up the gills of fish,鈥� says Northcott.
Anionic flocculants, which should be environmentally benign, also failed to
work. Northcott suspects that many of the particles in the run-off are actually
bits of clay or organic matter, which can only be removed using cationic
cleaners.
鈥淚t鈥檚 quite amazing. Organic material in Antarctic soil is usually
non-existent,鈥� says Northcott. She suspects that kitchen scraps, wood and other
organic matter thrown on the tip are being broken down by intense UV radiation,
turning parts of the waste dumps into compost heaps. Preliminary tests have
shown that soil beneath the tip is up to 18 per cent carbon, suggesting the
presence of large amounts of organic matter.
Northcott told the conference that a consortium of scientists hope to attempt
another clean-up of the Thala Valley in the Antarctic summer of 2002. They plan
to test other cationic flocculants that are safe for fish, such as one based on
chitin, a polymer found in the shells of prawns, as well as a range of other
techniques for removing particles.
鈥淭hala Valley is the smallest waste disposal that Australia has
responsibility for,鈥� says Northcott. 鈥淎cross the bay, there鈥檚 one that鈥檚 10
times as big, and they don鈥檛 dare touch it until we鈥檝e perfected the
迟别肠丑苍辞濒辞驳测.鈥�
